circuits assembly - december 2004 - digital...
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Welcome to the December 2004 digital edition of Circuits Assembly.
Metcal revolutionized hand soldering with the invention of the cartridge system nearly 20 years ago. While others are stilltrying to catch up to our constant temperature, variable power SmartHeat® technology, we’re moving forward again.
Introducing the PS-800 Soldering System - a new breed of Metcal that’s perfect for all repetitive soldering applications.
The PS-800 brings value to your bench by delivering all the power, process control and thermal repeatability of a SmartHeat®
cartridge in Metcal’s innovative ‘heater tip’ design. The heater tips are specially plated, so they last longer than competitivetips, even when soldering with higher temperature lead-free alloys. Plus, replacement heater tips are inexpensive andchangeovers are quick and easy.
The PS-800 Soldering System. Don’t wait years for a copy when you can afford the original - on every bench-top.
www.metcal.com Precision Systems for the Electronics Bench
The new PS-800Soldering System.
The more they copy us, the better we get.
DECEMBER 2004DECEMBER 2004 circuitsassembly.comcircuitsassembly.com
Quick ResponseManufacturing
Screen PrintingThroughput or Cycle Time?
Measuring ROIof Manual Operations
IN THE NEWS: Economic Outlook/Currency Squabbles/New RoHS Specs
How Does aSolder Joint Fail?We count the ways!
Quick ResponseManufacturing
Screen PrintingThroughput or Cycle Time?
Measuring ROIof Manual Operations
IN THE NEWS: Economic Outlook/Currency Squabbles/New RoHS Specs
How Does aSolder Joint Fail?We count the ways!
FEATURES
PROCESS CONTROL
20 Pb-Free Manufacturability and Test ControlLead-free solder is not a drop-in replacement electrically or mechanically. Determining the“sweet spot” between electrical contact and mechanical deformation.
Terence Q. Collier
LINE AUTOMATION
24 Can Odd-Form Automation Increase Returns?Still placing odd-form parts by hand? How to determine ROI of end-of-line automation.
Allen W. Duck and Patty Chonis
COVER STORY
28 Assessing Solder Joint Reliability in Pb-Free AssembliesA study finds distinctions between predictors of reliability for leaded and lead-free alloys.
Steve Dowds
SCREEN PRINTING
32 Throughput vs. Cycle Time in Evaluating Paste PrintingIs the best indicator of performance machine cycle time, or first-pass yield?
Joe Belmonte and Bob Boyes
PROCESS CONTROL
36 Enabling Quick Response ManufacturingEnd manufacturing and supply-chain redundancies through software that enables flexibleoperations and fast changeovers.
Doug Johnson and Vern Harrison
PARTS MANAGEMENT
40 Programming for Mixed-Vendor LinesCreating part data libraries for placement machines is time-consuming, error-prone and laborintensive. New tools can automate the process.
Bini Elhanan
ONLINE at circuitsassembly.comGearing Up for Pb-FreeOur contributing author reviews a training program and says nothing touches it.Bob Willis
ONLINE at pcdandm.comCOTS Ruggedization SimplifiedLinda Britt
PERSPECTIVES
5 Caveat LectorCracking the WIP.Mike Buetow
14 On the ForefrontA hard look at solid solder deposit.Phil Zarrow
16 Talking HeadsSiemens’ Tilo Brandis.Mike Buetow
18 EMS InsightA challenge to the new ODMs.Pamela Gordon
47 ESD BasicsA renewed need for ESD control.ESD Association
48 Process DoctorDiagnosing residue problems.Terry Munson
DEPARTMENTS
6 Industry News12 Market Watch30 Ad Index33 Assembly Insider42 Product Spotlight
ON THE COVER: Design andprocess factors are the focus of thismonth’s cover story.
D E C E M B E R 2 0 04 Vo l . 15 N o . 1 2
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circuitsassembly.com Circuits Assembly DECEMBER 2004 3
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were the European Union to call off the legislationtomorrow there’s enough momentum to switch anyway.“Component suppliers have jumped on this.”
From a processing standpoint it may not even causethat much grief. McCarron says – and others agree –most components are backward-compatible for lead-free processing and will be converted. (Parts that arenot include BGAs and flip chips, and those with tin-bismuth coatings. Yet despite knownreflow problems, says Bath, some sup-pliers are nevertheless implementinglead-free CSPs and BGAs.) Same goesfor makers of Class 2 product: A design-er at a maker of high-end power sup-plies and transformers says the compa-ny is following its standard approach ofperforming extraordinary process test-ing prior to ramp, and maintainingdedicated lead-free lines to avoid cross-contamination.
The approach, then, has been toextend the battery of tests to actuallead-free product coming off the lines,not just test vehicles. Dell, for example,is conducting testing for “HALT, ALT; every type of reli-ability test,” says McCarron. Likewise, EMS firms aretrying to extend the design-to-maturity cycle to test fortin whiskers and voids by mitigating such issues early,says Morgan.
If anything, the ramp may be already past. OneClass 3 OEM, we’re told, faced with losing its tin-leadparts, executed end-of-life scenarios for five to 10 yearsout to ensure a supply. Intel knows of OEMs that havetaken the same approach, performing “build aheads” astheir EOL plan for lead versions. Even the server andtelecom industries, which are exempt until 2010, aremoving rapidly because, as Morgan says, “they want toget it over with, because they are still liable for fiveother chemicals,” including bromine.
That would track with the latest SemiconductorIndustry Association poll. The trade group on Nov. 3forecasted a flat 2005 for semiconductors (with dropsin passives and memory offsetting modest upturns formicroprocessors, logic and DSPs).
It would appear, then, that generally speaking theoverall number of pieces built would remain the samethroughout the conversion process. So come 2005, don’texpect a healthy upswing in orders owing just to lead-free. Well, not unless all those environmentally friendlyI-Pods, cellphones and servers stop working.
Happy holidays everyone.
Caveat Lector
circuitsassembly.com Circuits Assembly DECEMBER 2004 5
W ill the conversion to lead-free products have anear-term increase on the total number ofpieces built for a certain part number? That’s
the question I asked component vendors, OEMs andEMS companies last month.
Why would it? Only because with so much cus-tomer satisfaction at stake, OEMs may seek a hedge justin case the number of failures and returns runs higheron lead-free assemblies. As such, the thinking goes, theymight overbuild inventories to ensure ample tin-leadreplacements.
For complex designs, OEMs are performing BoMscrubs, planning to be RoHS ready by Jan. 1, 2006 – sixmonths ahead of the deadline. (Makers of consumerdurables are either lead-free already or are expected towait until the last moment, to gain economies-of-scalefor lead-free parts.) One scenario has OEMs of high-relgear buffering stocks by placing orders for specificparts in lead-free versions while also ordering addi-tional safety tin-lead stocks, instead of simply (OK,maybe not “simply”) shifting en masse to alternatealloys. The result, then, would be a shift upward – albeita short-lived one – in end-product demand (at theOEM level, if not the end-customer).
Except the evidence, anecdotal and statistical, saysotherwise. (Damn.)
Dell Computer’s lead-free program director DaveMcCarron says that while the world’s leading computermaker will build and ship tin-lead and lead-free partnumbers simultaneously, the total pieces won’t change.So, for example, if Dell were to ship two million Dimen-sion desktops, that number would be divided (not nec-essarily equally) into tin-lead and lead-free versions.
Major electronics manufacturing services providersecho that sentiment. As Solectron senior manager oftechnical marketing Art Morgan says, customers are notdoubling orders and any increase would be marginal atbest. Advisory process engineer Jasbir Bath adds,“I don’tthink anyone has thought of overbuying … in case thereare more defects” in lead-free environments.
Ditto the analysts. iSuppli senior analyst Adam Picksays while he’s taken calls from OEMs seeking assis-tance on how to handle the conversion, he hasn’t heardof companies building stock for this scenario.
Even if OEMs wanted to build in reserves – and withthe swing to JIT inventory and Lean Manufacturing, theevidence is they do not – component vendors aren’tgoing along. Most vendors do not plan to maintain dualline cards. The reason, as Intel told me, is OEMs have“worked out most of the issues” with lead-free and arejust awaiting word from customers on when to ramp,probably the middle of next year. Solectron’s suppliersare moving to lead-free components and starting toremove from inventories tin-lead components for thesame part number. Once the shift is in full swing, man-ufacturers will have little choice but to acquiesce (or paya premium on the gray market). Morgan believes that
Mike Buetow, [email protected]
No Lead, and Hold the Extras
6 Circuits Assembly DECEMBER 2004 circuitsassembly.com
IndustryNEWS
Trade Groups Take Up Currency FightWashington – Discrepancies in the valuation of Chinese currencies remains a hot-button issue for
U.S. manufacturers. Backed in spirit by several trade groups, the nation’s largest workers union in Sep-
tember filed an action against China, saying it violates World Trade Organization rules by pegging the
value of its currency to the U.S. dollar.
The China currency issue has become a political football because of manufacturing’s insistence on a
substantial revaluation and the Bush Administration’s stated reluctance to hold China’s feet to the fire.
Hoping to capitalize on the issue’s high profile in the November elections, U.S. labor, textile and steel
groups on Sept. 9 filed a petition known as a Section 301 seeking a formal investigation into China’s
currency policy. Hours later, administration officials denied it.
On Sept. 30, one Republican and seven Democratic senators joined nearly 20 House Democrats in
refiling the petition. While a spokesperson said the Administration would meet with Congressional
members, there is no indication any punitive actions against China would be taken.
A coalition of trade groups known as the Fair Currency Alliance has spent the past year pushing for
a steep revaluation of the Chinese yuan. The FCA wants 40%, a number arrived at because, according
to one FCA member, there are data to justify it and room to negotiate.
However, disagreement in the ranks prompted the FCA to redraft the petition but the actual refil-
ing was left to the AFL-CIO. The FCA, whose members include the National Association of Manufac-
turers (nam.org) and IPC (ipc.org), operates on unanimous consent, IPC spokesperson John Kania
told CIRCUITS ASSEMBLY, and there was “heated debate” among its members as to whether to proceed
with the filing.
According to Kania, the AFL-CIO, steel and textiles industries advocated filing and NAM was strong-
ly against it. NAM assistant vice president of communications Hank Cox said because the Adminis-
tration had made it clear a Section 301 was out of the question, the organization felt another filing
would just embarrass the Bush Administration. NAM’s position, he told CIRCUITS ASSEMBLY, is “to let
them do it their way, with behind-the-scenes diplomacy,” a sentiment Kania echoed. (Kania, who
doubles as IPC’s liaison to the SMEMA Council, a group of assembly equipment makers, said the
council supports the petition because the issue affects its customers.)
China’s currency policy has for years rankled many U.S. economists and trade groups. China has said
on several occasions it plans to comply with WTO currency rules but has yet to move in that direction.
Says Kania, “The view of the Administration is that the Chinese know they have a problem. They need
to slow down their economy. Inflation is rampant, but to control it they need to raise interest rates.”
And China needs 8% annual growth just to absorb the crush of new workers, Kania says.
Separately, Congress in October repealed a law that gave tax breaks to American companies manu-
facturing abroad. The World Trade Organization, however, is considering an appeal from the European
Union that the law that replaced it contains violates international trade agreements.
The Extraterritorial Income (ETI) Act tax regime gave U.S. companies tax breaks on manufacturing
income earned overseas. ETI was repealed by the passage of the dubiously named American Jobs Cre-
ation Act, which offers a 9%, phased-in deduction for domestic manufacturing income. Also included
are a temporary tax break for repatriated income, reforms of various foreign tax credit rules and a num-
ber of other tax cuts targeted at businesses and individuals.
The ETI had little effect on most domestic manufacturers, but its repeal could have sparked higher
taxes had the American Jobs Creation Act not been passed. “The bulk of domestic manufacturers
don’t export and so they weren’t affected, but they would have received a tax increase,” says Kania.
Come January 2005, those companies will receive a tax deduction on a portion of their manufac-
turing income.
Building on its ODM capabilities, Flextron-ics (flextronics.com) will buy Agilent Tech-nologies’ (agilent.com) camera module busi-ness. Terms of the agreement, expected toclose at the end of 2004, were not disclosed.
V.J. Electronix (vjelectronix.com), an x-rayinspection technology and rework systemsprovider, opened a new office at 1735 Enter-prise Dr., Buford, GA. The company now hassix U.S. facilities.
Celeritek (celeritek.com) shareholdersapproved the sale of the company’s defenseelectronics business to a subsidiary of Tele-dyne Technologies (teledyne.com) for $33million in cash. Teledyne intends to relocatethe business from Santa Clara, CA, and con-solidate it with Teledyne Microwave inMountain View, CA.
Kulicke & Soffa Industries (kns.com)opened a state-of-the-art probe card man-ufacturing facility in Hsin Chu, Taiwan, amove designed to boost its vertical probecard market presence. The 2,400 m2 facto-ry will build enhanced cantilever probecards and can also handle probe wire diam-eters from 75 to 250 µm and very fine pitchprobing.
EV Group (evgroup.com), a wafer-bondingand lithography equipment suppler, and Dat-acon Technology AG (datacon.at), a flip-chipand die bonding equipment supplier, willdevelop and market advanced-chip-to-wafer(AC2W) technology. AC2W technology offershigh device density through stacked devices,short interconnects and higher functionaldensity, enabling the integration of variousdevice technologies.
Nu Visions Manufacturing (nvems.com) hasopened a CEM plant for PCB and electro-mechanical assembly in Tijuana, Mexico. Thefacility, located on a 670-acre site in TijuanaIndustrial Park, is equipped with SMT andthrough-hole manufacturing equipment,strict ESD controls and IT infrastructure iden-tical to its Springfield, MA, facility.
In Brief
Edited by Mike Buetow
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8 Circuits Assembly DECEMBER 2004 circuitsassembly.com
IndustryNEWS
New Report Shows Japan PCB TrendsTokyo – While Europe and the U.S. garner most of the headlines over the migration of produc-
tion to southeast Asia, Japan has not been immune. Japanese makers are moving advanced tech-nology substrates offshore at a quickening pace, according to a new report from a leading Japan-ese trade group.
Production of multilayer PCBs built by Japanese companies outside Japan will grow to 21.4% ofoverall production (based on 2003 values), versus 11.9% in 2003, says the Japan Printed Circuit Asso-ciation (jpca.org). The migration follows similar trends for single and double-sided boards; nearly 40%of flex circuits output by Japanese companies is already built offshore. The nation is holding onto high-er-end technology: offshore chip-package production will remain at just 5.3%. Overall, 27.2% of PCBsbuilt by Japan will be done offshore by 2008, up from 20.7% in 2003.
Other trends include smaller vias (down to 75 µm by 2006 for multilayer PCBs, from about 250 µmlast year; laser drilled vias up just 50 µm on buildup boards; and annular rings of 80 µm on through-via multilayers and less than 50 µm on laser-drilled buildup boads.
Economists Differ on Electronics OutlookScottsdale, AZ – A pair of economists who track the electronics industry offered in October differing
opinions on what’s in store for the recovering sector.The outlook for capital spending is “generally favorable” due to higher demand for replacement
equipment and a need for greater efficiencies, said Dr. Larry Chimerine. Companies are sitting on extra-ordinary cash reserves and financing is available from outside sources, said Chimerine, who spent 14years as manager of U.S. economic research and forecasting at IBM.
Speaking Oct. 15 at the TMRC meeting in Scottsdale, Chimerine said that although the environ-ment remains nearly impenetrable to product price hikes, companies will need to invest in newequipment in order to compete. “If you can’t raise prices, you must improve productivity 3 to 4%every year just to stay even” with higher energy costs, vendor price hikes and raises to employeewages, Chimerine said.
A somewhat different outlook was given by Ed Henderson of Henderson Ventures. Henderson, alongtime PCB industry analyst, forecast a slowdown in annual global GDP through 2006, and a cor-responding drop in equipment sales.
Annual GDP growth worldwide will slow from 4% this year to 3.5% in 2005 and 3.1% in 2006,Henderson predicted. Likewise, global sales of electronics equipment will drop from 13.4% this yearto 9.1% in 2005 and 5.7% in 2006. The figures are based on actual exchange rates.
The bare PCB market, now in its second year of recovery, will also fall, Henderson said. After 7.4%and 13.8% growth in 2003 and 2004, respectively, global PCB sales will slip to 6.4% next year as pre-lude to a 2006 recession, when sales will be 0.8% lower than in 2005, he said.
While pointing out that oil use as a percent of U.S. GDP has declined steadily over the past 20 years,Henderson said peaking oil prices could precipitate a sharp downturn. “Although a global recession isnot in the forecast, a sustained oil price in the $60 to $70 range could produce an economic down-turn in 2005.”
Chimerine singled out trade deficits as a major long-term hurdle for the U.S. economy. Noting tradebarriers enacted by several Pacific Rim nations, most notably China, that effectively squeeze Ameri-can-made products from Asian markets, Chimerine asserted that trade has become an economicgrowth issue.
“The outsourcing of production [is] the real drag” on the economy, he said. “The manufacturing basemust be strong. Not all chips [ICs, potato] are the same.”
U.S. trade deficits with China and overall have this year ballooned to all-time highs, with some fore-casts predicting a $550 billion gap by year-end. Pointing to the Bush Administration’s current policy ofnot waging battles over suspected currency manipulation by China, Japan and Taiwan, Chimerine said,”We are insane in keeping this in place.”
Elcoteq da Amazonia, a Brazilian sub-sidiary of Elcoteq Network Corp. (elcoteq.com), will manufacture Vitelcom MobileTechnology’s (vitelcom.es) CDMA mobilephones on a turnkey, assemble-to-order(ATO) basis. Manufacturing began in Man-aus, Brazil, in late October. Elcoteq will ini-tially provide logistics, manufacturing, test-ing and packaging services.
Universal Instruments’ (uic.com) SMT Lab-oratory offers a new Process Audit service toquickly optimize SMT and advanced packag-ing assembly. Each audit is performed as aconsultative process, and the structureincludes a review of the results from eachstage and scope to agree objectives for thenext step.
Canada-based EMS provider CreationTechnologies (creationtech.com) has estab-lished a Southern U.S. facility by acquiringSecond Source Systems (Richardson, TX). Thecurrent facility will be moved to a 40,000 sq.ft. location in Plano, TX, in January.
Pepperl+Fuchs (am.pepperl-fuchs.com)has acquired Omnitron (omnitron-ag.de), asupplier of of data matrix 2-D optical codingreaders for product identification or onlinedata recording.
EMS company Micro Dynamics (microdynamics.com) has sold a majority interest toCHB Capital Partners (chbcapital.com), a pri-vate equity group. Wells Fargo Bank has alsoprovided new financing.
The Z8 Encore!, eZ80Acclaim! and Crim-zon LP32300 microcontroller (MCU) familiesfrom ZiLOG (zilog.com) will receive pro-gramming support from BP Microsystems(bpmicro.com).
KIC (kicthermal.com) will partner withTamura Corp. (Tamura-HA.com), which willsell KIC products together with its lead-freeready reflow ovens and wave soldermachines.
Digi-Key Corp. (digikey.com) entered a dis-tribution agreement with Silicon Laborato-ries Inc. (silabs.com) to distribute SiliconLaboratories’ analog-intensive, 8-bit micro-controller product portfolio as well as wire-line, networking and synthesizer products.
In Brief
Our CM402 takes your productivity to stratospheric heights.For starters, the machine delivers ultrahigh-speed placement. But fast is not the whole story. You get more output from our CM402. It features unbeatable accuracy coupled with superior uptime that outperforms the competition. And with record worldwide installs, outsells the competition. The CM402 places a widerange of chips from 0201s up to 90mm x 100mm components in either high-speedor multifunction modes, onto boards as large as 18" x 20". Plus, it’s easy to programand operate the machine, which makes changeover efficient and provides greatercost savings.
The flexibility and productivity of our CM402 has raised the standard for high-volume SMT applications to new heights. Add it to your line, and you’ll see a shift in your bottom line’s landscape.
For more information on the CM402 visit www.panasonicfa.com or call 847.468.4000.
CM402high-speed interchangeable
platform placement machine
10 Circuits Assembly DECEMBER 2004 circuitsassembly.com
IndustryNEWS
New Standards on RoHSWashington – Although focused internally on meeting requirements of the Restriction of Hazardous
Substances Directive, OEMs are just coming to grips with the ability of their suppliers to comply with
the pending rules. The wakeup call: a finished product can contain thousands of parts, and a single
wrong component could be the difference between compliance and failure.
Suppliers and manufacturers inform each other of the composition of their parts through a document
known as a Materials Declaration of Inquiry. However, proprietary standards are rampant, although a
proposed standard is now being ratified by various trade groups.
While the standard makes the rounds, a guide for complying with material declaration requests, IPC-
1065, is expected to be available this month. Another document, IPC-1066, for board and component
labeling, is also in the works. See leadfree.org for details.
CAMX Still Seeking End-User PushGriffin, GA – The new CAMX standards for factory-level data exchange were the focus of a two-day
workshop sponsored by IPC (ipc.org), the trade group that helped author the specs. The seminar took
place Oct. 20-21 at NACOM, a tier-one automotive supplier.
Most attendees were already involved in the CAMX (Computer Aided Manufacturing using XML) API
project headed by Georgia Tech’s Manufacturing Research Center. These participants – Agilent,
Asymtek, BTU, DEK, Orbotech, Panasonic, Pillarhouse and Universal – shared specific experiences with
CAMX implementation. NACOM also detailed its switch to CAMX-compliant manufacturing during a
facility tour.
Cookson Group promoted Steve Corbettto chief executive of its Electronics division,
replacing Ray Sharpe, who left the company
last summer. Corbett was chief executive of
Enthone, Cookson's chemistries division,
since 2002. Also, Mike Murphy was named
regional marketing manager, Americas,
Cookson Electronics Assembly Materials, and
Bruce Moloznik was named global director
of product management.
Solectron Corp. named Matti Virtanensenior VP and president of Europe, the Mid-
dle East and Africa. He joined the company
Oct. 4. Virtanen has experience at Nokia,
Hewlett-Packard and Compaq.
The Electronics Group at
the National Physical Labo-
ratory has named Ling Zoutest service manager. Zou
joined NPL as a research
scientist in June 1997.
Perfect Commerce Inc., a provider of on-
demand SRM, appointed Daniel Rawlingsas executive VP of worldwide sales and
marketing and Sam Kaddah as VP of sys-
tems architecture and IT engineering. Rawl-
ings has experience at Ariba, Peoplesoft,
Lawson Software and Oracle. Kaddah previ-
ously directed eBusiness productivity for GE
Transportation Global Signaling division.
Three-Five Systems named David K.McQuiggan as senior VP of the company's
Platform Display business. McQuiggan was
CEO at Densitron Technologies, a designer
and manufacturer of embedded computing
products and information display systems.
Samuel Sher is the new vice president of
sales and marketing at Bliss Industries. Most
recently, Sher was a sales and marketing
consultant to technology-based companies
in Silicon Valley.
People
ESDA Honors Members, Elects BoardRome, NY – The ESD Association (esda.org) elected elected its 2005 board members and
officers during the EOS/ESD Symposium, in Grapevine, TX. New
board members include: Donn Bellmore, Universal Instruments
Corp.; Charvaka Duvvury, Texas Instruments; John Kinnear, IBM; and
Carl Newberg, Microstat Labs. The board’s officers are: Ed Wegge-
land, Static Control Components, president; Mark Kelly, Delphi Elec-
tronics & Safety, sr. VP; and Joe Bernier, Intersil Corp., VP.
The ESDA also honored Jack Smith, a recent retiree from Lockheed Martin and founder of
the first EOS/ESD symposium, with the Founder’s Award and Philip Kohlhaas with the Indus-
try Pioneer Award. During his career at 3M, Kohlhaas was instrumental in the introduction of
vital ESD control products.
SMTA Welcomes New Board MembersMinneapolis – The SMTA’s new board of directors began its term at SMTA International in
September. Bill Barthel, Plexus; Dr. Ken Gilleo, ET-
Trends LLC; Dick Russell, Clover Electronics; and Dr.
Laura Turbini, University of Toronto, were elected to
three-year terms. David Raby, president and CEO of
Soldering Technology International, was elected to a two-year term as president.
Election Updates
Americas Tel: +1.603.772.7778 Fax: +1.603.772.7776 E-mail:[email protected] Tel: +31.162.483000 Fax: +31.162.483253 E-mail: [email protected] Tel: +49.9391.98820 Fax: +49.9391.988228 E-mail: [email protected] Pacific Tel: +65.484.3010 Fax: +65.484.1910 E-mail: [email protected]
Get greater efficiency andperformance out of yourreflow soldering process withthe new XPM2 reflow systemfrom Vitronics Soltec! Withmore than 1,000 XPM systemsin the field, Vitronics Soltec’sproduction-proven XPM Seriesis known for repeatability and‘round-the-clock reliability.The new XPM2 is more efficient, offers enhancedfeatures, greater processcontrol and utilizes the provenXPM foundation. It also boastsa fresh, refined look thatfacilitates access and simplifies maintenance.
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12 Circuits Assembly DECEMBER 2004 circuitsassembly.com
MarketWATCH
SIA: Flat Semi Salesin 2005
San Jose – Record semiconductor salesof $214 billion in 2004 will be followedby flatness next year, the SemiconductorIndustry Association (sia-online.org) saidNov. 3. In its annual forecast, SIA pro-jects sales will grow 6.3% in 2006 and14.2% in 2007, reaching $259 billion.The trade group projects “less favor-able” demand for memory products willdampen expansion next year.
SIA expects that 2004 year-on-yeargrowth rate will be 28.5%. More than50% of the semiconductors sold in 2004will go into products purchased by con-sumers, a ratio that will grow as con-sumers embrace portable digital media,SIA said.
Driving AheadReno, NV – Will automotive drive our
future? After outpacing the overall ICmarket through the recession (the sectorfell just 1% in 2002), semiconductors forautomotive applications are expected toreach $13 billion to $15 billion next year,says Databeans (databeans.net), a mar-ket research firm.
According to an October report, de-mand for chips for cars and trucks isforecast to rise 9% per year through2009, well ahead of the overall vehiclemarket (3%).
Strike Up the Broadband
Cambridge, MA – Broadband Internetaccess is soaring in the U.S., according tothe latest data from Forrester Research(forrester.com). The number of house-holds with Internet access is forecast togrow from 68 million in 2003 to 83.7million by 2008, a 23% clip.Yet the num-ber of households with broadband willjump 226% during the same timeframe,from 19.5 million to 63.6 million. By2008, households with broadband willmake up 76% of all wired homes, For-rester says, up from 29% last year.
October Manufacturing Rejects SeasonalityTempe, AZ – The rate of growth in the manufacturing sector ignored historical seasonality in Octo-
ber, dropping for the third straight month. New orders upticked, but production dropped sharply. The
electronics industry appears to be slowing, said the Institute for Supply Management (ism.ws).
Manufacturing grew for the 17th consecutive month, ISM said, based on its monthly poll of the sup-
ply chain. ISM said that while growth remains strong, inflation worries are rampant. “Strong growth
continues, but at a slower
rate than in September,”
said ISM chairman Norbert
Ore. “However, energy prices
and commodity price infla-
tion are major concerns for
manufacturing buyers.”
The PMI measure of eco-
nomic activity fell 1.7 points
to 56.8%, but remained above the benchmark 50% level for the 17th straight month. New orders rose
0.2 points and production declined 6.8 points. “Manufacturing experienced three quarters of strong
growth this year [and] the decline in order backlogs is an indication that manufacturing has peaked,”
said Ore.
Trends in pricing (higher) and customer inventories (lower) continued. Order backlogs dropped in
October, yet imports and exports rose. Electronic Components and Equipment, and Industrial and
Commercial Equipment and Computers were among the sectors reporting growth.
June July August Sept. Oct.
PMI 61.1 62.0 59.0 58.5 56.8
New orders 60.0 64.7 61.2 58.1 58.3
Production 63.2 66.1 59.5 61.6 54.8
Inventories 51.1 49.9 51.7 51.0 48.2
Customer inventories 39.0 37.5 45.5 41.4 43.5
Backlogs 58.5 58.0 55.0 55.0 49.0
Source: Institute for Supply Management, November 2004
Book-to-bills of various components/equipment
June July August Sept.
Semiconductor equipment1 1.07 1.04 1.01 0.96
Semiconductors2 40.3% 1.0% 1.1% 1.0%
Rigid PCBs3 (North America) 0.95 0.99 1.05 1.01
Flexible PCBs3 (North America) 1.57 1.57 0.98 1.38
Sources: 1SEMI, 2SIA (3-month moving average growth), 3IPC
Trends in the U.S. electronics equipment market (shipments only)
--------------------------- % Change ---------------------------July Aug. Sept.* YTD
Computers and electronics products 3.0 1.6 -3.5 13.1
Computers 7.7 -2.5 -4.7 13.5
Storage devices 1.1 -0.2 2.1 11.3
Other peripheral equipment 7.6 4.2 -13.1 6.1
Nondefense communications equipment 3.8 7.1 -7.9 10.4
Defense communications equipment -2.9 1.6 -1.6 20.5
A/V equipment 3.6 9.0 -10.1 0.4
Semiconductors 5.1 -0.5 -5.4 22.3
Components1 1.2 -0.4 0.3 9.6
Nondefense search and navigation equipment -13.4 7.4 6.0 7.3
Defense search and navigation equipment 6.3 0.0 1.7 9.6
Medical, measurement and control -1.3 2.4 -0.1 14.3
* Preliminary. 1Includes semiconductors. Seasonally adjusted. Source: U.S. Department of Commerce Census Bureau,
November 2004.
Talking Defense
Industry Market Snapshot
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On theForefront Phil Zarrow
ish, OA (water-soluble) fluxed solder paste is used. Afterreflow, the PCB passes through an aqueous cleaner. Thenext step is a flattening operation that uses two heatzones and a cold press plate to flatten the solder depositflush with the top of the mask. For a double-sidedassembly, the solder deposit and reflow steps are repeat-ed for the second side prior to flattening. Finally, anadhesive no-clean flux is applied to the solid solderdeposit, cured to a tacky finish, covered with protectivepaper and shipped to the assembler.
The first step in assembly is removing the protectivepaper and exposing the tacky flux. This replaces theprinting operation since the solder and flux are alreadyin place. (Note: peeling the protective paper requiressomewhat less skill than printing paste.) The boards arethen populated and reflowed in the usual manner.That’s it.
This technology is worth examining for a number ofreasons. First, solder paste deposition is eliminatedfrom the assembly operation (recall that the combina-tion of paste characteristics and printer parameters typ-ically account for approximately 50% of assembly
14 Circuits Assembly DECEMBER 2004 www.circuitsassembly.com
Phil Zarrow is
president and
SMT process
consultant with
ITM Consulting,
(ITMConsulting.org);
phil_zarrow@
itmconsulting.org.
SSD: The Other Surface FinishWith lead-free and via-in-pad designs, solid solder deposit may finally
find its niche.
“There’s a time for us, a special place for us…”Steven Sondheim, West Side Story
M any assemblers are not familiar with a con-cept called solid solder deposit. Solid solderdeposit (SSD) is a method whereby solder
material is deposited on the PCB substrate by the fabri-cator. The assembler has no need to print solder paste;the solder deposit is already there. Typically flux isadded and the PCB passed to component placement.The tackiness of the flux keeps the components affixedto the board. Following component placement, boardsare reflowed in the usual manner.
Solid solder deposit process technology has beenaround for some time, 18 years to be exact. A number ofsuch processes exist, but one of particular interest is theoriginal technique. Called Sipad, it was invented bySiemens in 1986 (not all material and component tech-nologies have their roots in IBM and Bell Labs/AT&T inthe mid 1960s). It remains one of the most economicaland viable SSD techniques and is downright cool!
Sipad begins with the application of a special solder-mask. Originally, the process useddry-film mask (remember, thiswas 18 years ago). Today’s processuses LPI (though dry-film can beused; either way guidelines mustbe followed). The thickness is typ-ically about 100 µm. The mask isapplied to the PCB and exposed,developed and cured, similar toany soldermask material.
Now comes the fun part. Solderpaste is stencil-printed onto thePCB – by the fabricator. The sol-dermask, in conjunction with thestencil thickness, defines the vol-ume of solder applied to the land.The board is then passed through areflow oven, where the solder isbrought to reflow temperature andthen cooled. Applied over barecopper, gold, silver, HASL or virtu-ally any solderable surface fin-
FIGURE 1: Solid solder deposit may get a boost as a lead-free surface finish. Here,the Sipad process of paste on pad is shown.
SIPA
D Sy
stem
s
www.circuitsassembly.com Circuits Assembly DECEMBER 2004 15
defects). Paste alignment, paste work life, depositionprecision, low humidity: all become non-issues. Also,post-print inspection is not necessary. Paste height iscontrolled and consistent, ideal for area arrays likeBGAs, CSPs and flip chips. And yes, the precision of thephotomask film lends itself nicely to fine pitches. Itworks well on QFPs with 0.4 mm (0.16") lead pitchesand with 0402s.
If the concept is so good, why don’t wesee more SSD? Many of the other SSDtechniques I’ve seen require specializedequipment and processes. A board fabrica-tor has to see the demand for the technol-ogy before investing in the capability; mostchose not to. Sipad is not immune; itrequires a special flattener and it is a pro-prietary process that must be licensed.Beyond that, it is straightforward: to a PCBfabricator soldermask technology is notsomething new and scary.
SSD is a good process to consider fortwo other key reasons. First is that oldnemesis to assemblers: via-in-pad syn-drome. Perpetrated upon us by the designfolks, the situation gets worse as componentdensity and pin-counts increase. Via-in-padaccounts for insufficients and opens inmany joints, and is extremely deadly (andprevalent) in area arrays. This designattribute contributes a great deal to thepresence of voids in solder joints as well.Tenting is problematic and not always pos-sible. SSD eliminates the problem becausethe solder deposit has already dealt withthat pesky via.
Then there’s another nemesis, lead-free,which is coming at us like a train (T-19months and counting!). With the debate andconcern regarding the cost of silver, embrit-tlement, tin whiskers and the like, SSD of alead-free alloy (e.g., SAC 305) is a viable lead-free surface finish. Depending upon theapplication, virtually any alloy could be used,including higher temperature blends. It evenappears to enjoy a longer shelf-life than OSPs(and without the exposed copper in the cor-ner of the pad).
But don’t consign the printer to storageyet, since SSD is not for everyone. Sipadlends itself nicely to single-sided assem-blies. For double-sided SMT boards, thesecond side will require a flux application.This can be printed or even sprayed on.The technology is application driven. In
this case, though, it appears to be a widening niche.This technology will continue to evolve as it has a lotgoing for it.
Special thanks to Matt Kehoe of SIPAD Systems Inc. for the history
and background of SSD, and Don Johnson of DuPont, who taught me
more than I ever wanted to know about dry-film soldermask.
On theForefront
T H R O U G H H O L E R E F L O W
Call 1-800-322-3225 or visit www.phoenixcon.com/thr
© 2004 Phoenix Contact Inc.
Want through-hole stability andreduced PCB board assemblycosts? Phoenix Contact’s COMBICON THR (Through Hole Reflow) terminal blocks and headers are engineered to withstand the heat of theSMT soldering process,eliminating the need for time-consuming secondary wave or hand soldering.
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TalkingHeads
key factor is that we always cooperate with the bestpartner for the specific solution – and this partner canbe different in different areas of the world.
CA: Can a maker of factory automation equipmentcapitalize on the push toward so-called environmen-tally friendly processes? Or will capex budgets beconsumed by process equipment (reflow, wave andscreen printing, AOI, etc.)?
We support our customers [need] to capitalize frommarket demand. Of course, Siemens is working in con-junction with other equipment suppliers to ensure thatprocesses will run smoothly and be environmentallyfriendly throughout the production chain. With ourconsulting expertise we consider all aspects for cost-optimized production.
CA: Volkswagen, among others, has outsourced theactual in-plant management of various parts of theirlines to the makers of the equipment. Do you see a daywhere electronics manufacturers will do the same?
We don’t believe that most electronics manufactur-ers will go to outsourcing actual in-plant management,but there will be many who rely on Lean portfolios tostreamline processes with the help of qualified profes-sional consulting and truly integrated logistics solutionsfor their lean production.
CA: What are Siemens’ technology goals for thenext 18 months?
With our new machine platform, Siplace HF, we’vemoved in the right direction, but this is just the begin-ning. We will soon have another generation ofmachines on which we will again build on [such] fea-tures as modularity and flexibility, speed and accuracy.Modularity and flexibility will always be the basis ofour success. Of notable importance is the adoptionand processing of 01005 size passive devices, high-speed flip-chip processing and stacked die applica-tions. Siemens is addressing these technologies with itsnext generation of equipment.
Attention will undoubtedly be focused on gettingmore from less and improving material managementthroughout the supply chain. Whether manufacturingin a high-mix environment or not, a true build-to-orderand lot size one capability will be required. Further-more, the integration of line production processes intothe customer’s software environment will becomeincreasingly important. Siemens already offers suitablesolutions [in this area].
Our Lean solution enables manufacturers to removeall non-value activity from production. Overall, costreduction in production and very flexible build to cus-tomer order capabilities are becoming more important.This implies modularity and software tools. With ourprogressive software tools we are able to optimize theentire production process and the productivity of pro-duction lines on different levels.
16 Circuits Assembly DECEMBER 2004 circuitsassembly.com
J ust 18 months ago Tilo Brandis was named presi-dent of what is now Siemens Logistics and Assem-bly Systems (siplace.com). Though only 36 at the
time, Brandis had already successfully run a pair of sub-divisions within the Siemens Transportation SystemsGroup.
Still, he was tasked with building on what was alreadyan 11,000-employee, €3 billion division. CIRCUITS ASSEM-BLY’s Mike Buetow caught up with Brandis last month.Excerpts:
CA: We’ve seen a trend toward smaller, more flex-ible and modular equipment and platforms. Can weexpect this to continue for the foreseeable future?
Yes, the modular platform architecturestrongly supports greater requirements forflexibility, even for traditional “volume only”customers. Fixed production lines that han-dle only a limited product spectrum are athing of the past in Europe and the U.S. Theyare inflexible for today’s requirements. Mod-ularity is the overarching imperative. Of par-ticular interest are gantry machines. Thesecan be used as standalones or in a networkwith others for improved throughput andeven greater flexibility. I would look for thesemachines to be increasingly popular in meet-ing market demands.
CA: What types of Lean Manufacturing is Siemenspromoting?
We are convinced that the principles and methods ofLean are now becoming important in electronics man-ufacturing. Everything that’s superfluous must be elim-inated from the production processes. At Siemens, weare addressing Lean with features such as fasterchangeover time with offline setup, virtual productbuild, visual factory, manufacturing transparency,shorter cycle times and long-term sustainable accuracy.Our goal is to help our customers reduce costs whileproviding a level of quality that can form the basis forzero-fault production. We have been successful in part-nering with our customers to achieve, on average, 15%less scrap, rework, returns and waste. This equates todollars in the bank for our customers.
CA: Many companies have tried to offer turnkeymanufacturing solutions, with marginal success. Canwe expect buyers will continue to piece lines togeth-er, or have you seen any strong evidence of a trendtoward turnkey procurement?
There are companies that ask for the full-scale solu-tion, and others only want parts of it. We see a trendtoward complete solutions, as manufacturers especiallyin the U.S. and Europe have to decrease cost. To delivertailored solutions, we must be prepared to partner withother leading companies. Siemens is not restricted tojust one or two companies in a specific field. For us, the
Siemens: Getting ‘Lean’
Siemens’Tilo Brandis
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18 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Pamela J. Gordon
is president of the
market analysis
and strategy consul-
tancy Technology
Forecasters Inc.
(techforecasters.com);
pgordon@techforecas
ters.com.
T he list of electronics manufacturing servicescompanies entering the original design manu-facturer market is long and growing longer: Flex-
tronics, Sanmina-SCI, Celestica, Elcoteq, GES, USI, IMIand Pemstar, to name a few.
As the EMS business model changes from manufac-turing products on spec for name-brand customers todesigning original products and owning the intellectualproperty, business opportunities and challenges occur:
• Opportunities for new revenue. TFI forecasts fastergrowth in the ODM sector than in EMS over the nextseveral years.1
• Operating two concurrent and distinct businessmodels. EMS and ODM companies are managed differ-ently according to business form, value proposition,cost structure, pricing practices and operating charac-teristics.2
• Leadership in innovating technologies and prod-ucts that perform new and useful functions while con-serving resources and creating sustainable jobs.
The opportunity for leadership in design innovation– and the potential to benefit the electronics industry,the macro economy and society at large – is the focus ofthis column.
Who are the leaders in electronics innovation? Mostlists would include large name-brand OEMs – IBM, HP,Lucent, Sony – or perhaps startup companies with total-ly new product ideas. Certainly, R&D within blue-chipcompanies is critical. Less well-known, however, in manyOEMs’ new products are innovations by ODMs: newcomputer platforms designed by Foxconn as well asunique products such as Elite Industrial Group’s Sound-Bug (which turns any hard surface into a speaker) andprinter products with greater functionality in a smallerfootprint. Unencumbered by brand definitions or a sin-gle market sector,ODMs’design engineers have free reignto develop new concepts leading to saleable products.
EMS companies new to the ODM model may haveeven more success than longtime players. EMS compa-nies manufacture a range of products for diverse indus-tries such as automotive, industrial, medical, network-ing and military/aerospace. This holistic experience ofimproving customers’ designs, troubleshooting manu-facturing issues, finding cost savings through efficiency
Pamela J. Gordon, CMC
and interfacing directly with end-customers at timesgives EMS firms greater insight than OEMs and ODMsto the needs of businesses and consumers.
EMS companies may benefit most in countrieswhose governments are investing in R&D and educa-tion. In the early 1990s, for example, Finland cut gov-ernment spending by 20%. The two areas not cut: edu-cation and R&D. In fact, R&D investment was increased.Beneficiaries were not only Finnish citizens whoseemployment figures are way up, but also Nokia, Elcoteqand other companies who enjoy robust R&D skills anda highly educated workforce. China’s central govern-ment is considering investing the equivalent of billionsof dollars in R&D to elevate its workers’ value globally.Already, China graduates hundreds of thousands ofengineers each year; depending on the nature of thegovernment investments, EMS and ODM companies inChina may leverage these investments to foster innova-tion.
EMS companies not only have a significant opportu-nity to provide environmental redesign and recyclingservices for OEMs, but also an opportunity to designand build new products with superior environmentalproperties from the outset. It’s less expensive and quick-er to design a new product, with qualifying bills of mate-rials, ease of recycling and other resource-efficient prop-erties, than to revamp an existing one and changeprocesses midstream.
In the last 25 years, the EMS industry has distin-guished itself by its growth, the massive conversion tothe outsourcing model, its expansion of services andestablishment of a multinational footprint. Now asmany EMS companies act as ODMs, I challenge theindustry to own patents for hundreds of the most inno-vative, useful and resource-efficient products used bybusinesses and consumers for the next 25 years.
References
1. Technology Forecasters, Electronic Manufacturing OutsourcingReport: 5-Year EMS and ODM Forecasts by Industry Sectorand Geography, December 2003.
2. Technology Forecasters, Original Design Manufacturers: ViableAlternative/Distinct Business Processes, June 2004.
The ODM Challenge: BecomingLeaders in Design InnovationAs they make the jump to ODM status, EMS firms must take control of IP.
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MPM Gel-Flex
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Process Evaluation
A few years back, lead-free initiativeswere pushed aside as a passing fad.How times have changed. Many
Japanese companies have converted tolead-free, and a number of European andU.S. companies are in transition. Manydesign managers waited until more direc-tion was available because they did notwish to incur the cost of redesign andrequalification of product for a directive(WEEE and RoHS) with implementationdates changing as fast as the potentialreplacement alloy. One date for completeconversion in Japan; a different date for theEuropean Union’s deadline, coupled withresistance to change from the U.S.
Lead-free product is important for anumber of reasons but two stand out. First,the semiconductor industry generates reamsof waste material containing lead, materialthat eventually makes its way into the envi-ronment. Second, in practice operators oftenperform hand soldering (and generate sol-der fumes) in common areas away fromexhaust vents. Other large-scale operations –from mining to SMT ovens – also add lead tothe environment. Added to the worldwidepush for environmental stewardship, it
should have been apparent that the transi-tion to lead-free was real.
Converting to lead-free is not simply ver-ification of long-term reliability nor is itsimply verification of temperature excur-sions (on material sets) to 260°C. Conver-sion to lead-free is verification of manufac-turability and test. If these time-zero resultscannot be met, the alloy is not a suitablereplacement. If one cannot build the prod-uct and maintain control, then the process isnot viable. Understanding how lead-freeimpacts performance and process control iscentral to its implementation.
When switching from lead-rich (PbR) tolead-free materials, additional variablesshould be added to the failure modes andeffects (FMEA) process. Mechanically, lead-free materials are typically “harder” thanhigh-lead materials. Data typically quoted inliterature list the bulk properties of a solidsample (standard cubic area and mass).Unfortunately, the post-reflow solder alloy isneither in a bulk state nor is the post-reflowhomogeneity consistent with the startingalloy. (Gold, copper, nickel, palladium andother metals can contaminate the alloy,changing the mechanical modulus.) Missingare convenient charts that provide mechani-cal deltas comparing small spheres versusbulk solids. Missing are charts that show thedeltas when the target is a stud versus no-stud flip-chip die. Missing are charts thatshow the change in electromechanical prop-erties of lead-free alloys.
A process for determining the sweet spotbetween electrical contact and mechanicaldeformation for lead-free solders.
Pb-free Manufacturability and Test ControlTerence Q. Collier
20 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Process Evaluation
circuitsassembly.com Circuits Assembly DECEMBER 2004 21
Careful examination of the contact areabetween the bump and outside environmentreveals that hardness has a dramatic impact onsocket design, electrical contact (impedance andcontact resistance) and overall yield. Not only arethe lead-free alloys typically harder, the com-bined surface oxide/residual flux coating canhave varying impact on the electrical first contactand contact resistance.
Two off-the-shelf BGA components werereviewed (same package, one PbR the other lead-free; the exact alloy composition is irrelevant forthis process) to assess the impact of the solderconversion. Figures 1 and 2 demonstrate a signif-icant load delta to obtain similar bump deforma-tion. (The degree of deformation directly correlates with theminimum force required on the bump to make electrical contact.The deformation selected is typical for an electrical contact usinga tin-lead alloy.)
As Figures 3 and 4 highlight, the high-lead device will deformup to 50% more than the lead-free alloy at this target load. Thehigh-lead device will also retain as much as 75% more deforma-tion than the lead-free alloy after the load is removed. This phe-nomenon relates to the mechanical properties of the PbR solder.This phenomenon is even more pronounced on copper-studdedflip-chip packages when compared to a non-stud type. Changesin the bump chemistry results in a continual change in the met-allurgy and mechanics; this is likely due to dissolution and alloy-ing of copper into the solder.
When looking for methods to improve BGA-to-socket or flip-chip-to-probe-card life and to understand how conversions fromPbR to lead-free could impact electrical and mechanical perfor-mance, physical testing is necessary. For flip chips, to determineif yield can be improved and better process control maintained,a comparative analysis of the electromechanical properties isnecessary. With the proper tool setup (this process uses a modi-fied tool from CSM Instruments), electrical contact resistance –as well as true electrical first contact and mechanical durability –can be easily obtained.
In our evaluations, we determined the sweet spot betweentrue electrical contact and mechanical deformation to suggestbetter process control. The data suggest that the conversion fromPbR to lead-free is not a drop-in replacement electrically ormechanically, regardless of reflow temperature. The process alsoprovides the investigator an early opportunity to evaluate theimpact of misaligned test hardware on solder bump reliability:Slight offsets in alignment can skew results of mechanical testson finished product.
Electromechanical data provides the process/design FMEAowner unbiased data in the alloy selection process. The abilityto select the appropriate materials based on hard data versusmodeling removes guesswork from engineering, resulting in“right the first time” setup, socketing and interface hardware.Electromechanical characterization for the alloy not only helpsthe package owner, but aids device design. Mechanically as well
as electrically, silicon can be damaged due to the increased loadsrequired to socket and test the package. Equally important, flip-chip devices with low k structures could suffer reliability issuesif the force required to make electrical contact exceeds mechan-ical load limits.
Small geometry PbR flip chip bumps typically requirebetween 15 to 20 grams per bump to make electrical contact.
FIGURE 1: Tin-lead bump with 20 g ofload. Typical contact point (flat spot) forthe load.
FIGURE 2: Lead-free bump with 20 g ofload. Much smaller contact point on thesurface.
FIGURE 3: Load versus deflection curve for a tin-lead bump. The bumpdeforms about eight units across the scale per given load.
FIGURE 4: Under the same load, the lead-free bump deforms just fivegrids across the chart. The delta suggests possible process controlissues if not properly characterized.
Worldwide Headquarters • 600 Route 440 • Jersey City, NJ 07304 • USA • 1-800-367-5460 • www.alphametals.comEuropean Headquarters • Forsyth Road • Sheerwater • Woking GU215RZ • United Kingdom • 44-1483-758-400Asia-Pacific Headquarters • 1/F, Block A • 21 Tung Yuen Street • Yau Tong Bay • Kowloon, Hong Kong • 852-3190-3100
alpha
That is enough devices for every man, woman and child in Germany and France combined. Morethan enough for the entire population of Japan. With each of our product technology’s performanceat a level that exceeds the competition more than 8 out of every 10 times. Accelerate your cost-effective transition to lead-free processing with Cookson Electronics’ Technologies.
• ALPHA OM-338 Solder Paste – wide process window, low voiding, excellent print consistency• ALPHA Stencils – lead-free design rules for accuracy and consistency• ALPHA Vaculoy SACX0307 Solder Alloy – high yield and value, fast throughput and high reliability• ALPHA EF-Series Wave Solder Flux – provides industry-leading lead-free solderability• ALPHA Telecore Plus Cored Wire – offers complete lead-free compatibility• ALPHA Exactalloy Solder Preforms – deliver precise volumes of lead-free solder• ALPHA Solder Spheres – full range of alloys and sizes for optimal sphere joint performance
For the most extensive knowledge base and compatibility with the widest range of lead-free products,call Cookson Electronics today (800)-367-5460, or go to www.alphametals.com/lead_free
The number of devices that are now
lead-free as a result of Cookson Electronics’
industry leading technologies.
Process Evaluation
circuitsassembly.com
Our team uses a modified CSM-Instru-ments microhardness tool to make quickestimates of the force deltas required tosimulate stable electrical contact andyield. Results show lead-free material setscan require up to 70% or more load foran equivalence. (The results were validat-ed using Kelvin connections and a four-point probe setup to show a delta of74%. The CSM tool takes approximately5 minutes, while the Kelvin connectioncan require up to two weeks to obtainresults.) Instead of standard bulk resistiv-ity and hardness, designers and processengineers should demand the type ofdata discussed herein from solder andsphere suppliers.
Additional variables that might ratehigh on the FMEA and possibly impactperformance (hardware and device alike)such as flux residue, oxidation and alloycontamination should be evaluated in thesame context as the bump alloy. Rinsesand other processes that claim to cleanbumps by removing flux residue andoxides can be added criteria to be validat-ed in a design of experiments. The DoEprocess might be concluded by suggestingthe correct probe needle design for thebump alloy to match prior target yields,increase throughput and optimize hard-ware design.
Optimizing the probe needle designto bump geometry is necessary to helpprevent damage while effectively pene-trating barrier layers of flux residue andoxidation to make electrical circuit(some bump deformation is required tomake electrical contact; excessive loadleads to damage and yield loss). Thisprocess has been streamlined frommonths (with marginal results) to a fewdays (with accurate test results). A com-plete analysis on solder bump deforma-
tion and electrical optimization can takeless than three days with the right setups,increasing process, device and equipmentoptimization.
Finally, when comparing lead-free toPb-rich solder, note that variation indurability between solder bumps on flip-chip and µBGA packages can occur dueto change in scale (bump geometry of250 µm versus 750 µm). A “deforma-tion” delta is observed when loading atdifferent max load values. Experimentalresults were in line with actual testresults by less than a 5% margin of error.(Part of the error could be eliminated ifthe Kelvin connection had been fac-tored.) This delta can be critical for testhardware designs, preventative mainte-nance (PM) and die fracture, particular-ly when the lead-free bump is above thelow k pad. Excessive loading on a pack-age or die could lead to hardware dam-age and equipment downtime. If work-ing with lead-free solders, particularlyover low-k structures, an analysis similarto the one discussed herein can beinstrumental in time to market andimproved reliability.
Terence Q. Collier is a founder of CVInc. Business
Solutions (covinc.com); [email protected].
The combined surface oxide/residual
flux coating can have varying impact
on the electrical first contact and
contact resistance.
Cookson Electronics
Surface Mount
Technologies
Our surface mount technologiesare part of the world’s mostcomplete line of lead-free solu-tions. Their proven compatibilityhelps you transition to lead-freeprocesses seamlessly.
• ALPHA OM-338 Solder Paste –wide process window, lowvoiding, excellent print consistency
• ALPHA Stencils – lead-freedesign rules for accuracy andconsistency
• ALPHA Telecore Plus CoredWire – complete lead-freecompatibility, activated rosin,halide-free flux core, non-corrosive residues
For more information on CooksonElectronics Wave SolderingTechnologies, call:Americas + 1-800-367-5460Europe + 44-1483-758-400Asia + 852-3190-3100 www.alphametals.com/lead_free
alpha
Line Automation
L ike so many phrases, return on investment isoverused, yet engineers accustomed to dealing withSMT, VOC, PTH and ICT now utter ROI as part of
their everyday language. But do we know what ROI reallymeasures in the manufacturing arena? Do we understandhow it can be used to justify and quantify investments incapital equipment? And is ROI even an appropriate datum,given the available manufacturing information flows?
As a simple equation, ROI can be described as
ROI is a historic reference point. It cannot be determinedas fact that any investment has made or lost money untilafter a period of time has passed. Companies use ROI moreas a target, a corporate goal and a measurement of manage-ment effectiveness. For those buying and selling machinery,the term is often misplaced. Other metrics that could bemore relevant to capital justification are positive cash flow,payback period, tangible quality improvements, floor spacesavings and reductions in cost-of-goods (COG).
Within electronics assembly, the avenues of competitiveperformance have been explored to the extent that very fewtangible increases in efficiency can be attained. Financeoptions have brought cash flow and improved results, newSMT machinery has reduced overall footprint and AOI sys-tems permit QA to be validated at multiple points on the
assembly line. In addition, the cost of equipment has signif-icantly declined due to economic and supplier pressures.
Faced with a less than 3% (in many cases) reduction inmargins and increased capacity, are capital expenditures areasonable agenda item for the next management meet-ing? Without a doubt. To curtail technology investmentswill quickly result in technological obsolescence, impact-ing any potential competitive advantages.
The past 12 months have taught us many lessons, notthe least of which is the impact of labor on the efficiency ofa company and the COG of its products. When demandpeaks, manufacturers need to make their profits. This oftenleads to large capital outlays for new plants and machinery.Furthermore, increases for labor are sought to support themachinery and fulfill the manual elements of assembly –impacting variable costs.
Much of the capital outlay is kept off the balance sheetthrough the use of lease companies and cash outflow isminimized via the same financing mechanisms. Inessence, machinery is justified and supported throughcash flow. Machinery is disposed of, moved to other facil-ities, sold at auction or returned to the financers. The orig-inal cost is seldom realized if a machine was purchased,although some degree of return is ascertained. In effect,there is a cash inflow or cessation of cash outflow whencash is most important.
Labor is the greater issue in that the costs of hiring arenot inconsequential. Recruitment, training, retention,qual-ity, productivity, infrastructure: all have associated costsdirectly linked to the labor element of manufacturing.
Labor that has cost so much in recruitment, training andretention may become redundant with production fluctua-tions. The cost of redundancy does not come withoutpenalty. Most companies exercise severance programs thatcover employees for periods of time employed and fund
Still placing odd-form parts by hand?How to determine ROI of end-of-lineautomation.
Can Odd-Form Automation Increase Returns?Allen W. Duck and Patty Chonis
24 Circuits Assembly DECEMBER 2004 circuitsassembly.com
(Profit/loss before extraordinary items + interest expenses) 100
(Total assets – non interest-bearing liabilities)
Kester’s EM907 No-Clean Lead-FreeSolder Paste is designed to exceedcustomers’ expectations for highyield lead-free manufacturing.EM907 is a newly engineeredproduct specifically for the highthermal demands of assemblingwith lead-free alloys such as thefamily of SnAgCu (SAC).
• Lead-free joints that arecosmetically bright as SnPb joints
• Excellent solderability to a widevariety of board and componentsurface metallizations
• Maintains excellent print quality at high print speeds up to 6 in/sec(150 mm/sec)
• Extended printing downtimes and long stencil life
• Anti-slumping to eliminate bridgingand micro-solderball potential
• Excellent printing characteristicsto 16 and 20 mils pitch (0.4 and0.5 mm)
• Prints down to 0201 pad sites
• Light colored residue
• Designed for air reflow as well as nitrogen
• J-STD-004 Flux Classification ROL0
Call Kester today for a brighter future.
Who Says Lead-Free Is Dull?
Kester’s EnviroMark 907Bright Solder Joints and a Whole Lot More
EM907 Solder Joint
Typical Lead-Free Solder Joint
Global Headquarters:Des Plaines, IL USA
Branches:Canada TaiwanGermany MalaysiaBrazil JapanSingapore
For additional information:visit www.kester.comcall 800-2-KESTERfax 847-390-9338
Line Automation
benefits even after the employee has left the company. And peopletake up space. That space quickly becomes vacant in a reorganizedfacility and the general overhead rate increases as a percentage ofoutbound products when factoring in cost of property.
We come full circle: letting staff go is also a financially, emo-tionally and organizationally expensive exercise.
Here is the critical question: What could be done differentlyand where should investments be made that permit a companyto grow efficiently while also protecting itself against variablecosts of fluctuating labor requirements?
For some corporations, the answer is to move offshore toregions offering low-labor rates. Such a move makes sense formultinational companies, but is simply not realistic for others –local markets need to be served locally and not everyone canafford the time and monies associated with offshore manufac-turing. The dynamic between large-scale manufacturers andsmaller ones is changing and greater proportions of finishedproduct and subassembly parts are coming into the U.S. fromChina, but it is simply not possible for this trend to continueunabated. It does, however, provide yet another opportunity forU.S. manufacturers to make gains in efficiency and competitive-ness. The U.S. market for electronics is massive, and in the con-sumer arena the costs associated with offshore manufacturingand importation are not inconsiderable, providing an advantagefor those that are U.S.-based and capable.
Where do the investment opportunities lie in automation thatcould possibly make a difference? Looking back, the advent ofvolume SMT was the downfall of the leaded through-hole com-ponent. No package type or electrical performance requirementwould be left untouched by the newer, smaller, on-the-top phe-nomenon. Yet almost every board has some type of odd-formcontent, and through-hole components linger for certainmechanical or electrical performance needs.
As automation levels rise and SMT becomes faster and cheap-er, the few components left with leaded terminations have beenmanaged by most companies through the application of manuallabor – which is highly variable. Most eschew the idea ofautomating the final stages of component assembly in favor offlexible manual operations, even at the critical point when theadded value of the SMT assembly is at its highest and the risk ofmisinsertion, misorientation or wrong part insertion will mostaffect product cost (and operating profits).
The reasons to avoid automation are well-founded: Odd-form insertion systems historically have lacked flexibility, arelarge relative to the number of components being handled andare expensive. Plus, the unspoken belief remains that the fewleaded components may be designed out at the next iteration.
However, when all the elements of variable content are accu-mulated, the costs of not automating may in many cases be sig-nificantly higher than many manufacturers realize, including
26 Circuits Assembly DECEMBER 2004 circuitsassembly.com
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Line Automation
circuitsassembly.com Circuits Assembly DECEMBER 2004 27
labor, floor space, rework, product handling, re-test and cost ofmaterials in circulation (Figures 1 and 2).
With diminishing margins and the drive to squeeze theprocess in terms of repeatability, reliability and consistency,automation may be the difference. The one area of machine tech-nology that has been subtly improving over the past four yearsand provides an avenue for further exploration is automatedodd-form equipment. (Authors’ note: “Odd form” conjures aninaccurate image. A more accurate term would be end-of-lineautomation, which recognizes the traditional break point whereautomation gives way to other operations from test to manualassembly, rework and finally to box-build.)
The humble odd-form machine has come a long way. In theway that the MPS 525 and MS90 gave way to Fuji and Siplace,EOL automation has transcended the highly custom and special-ized robotics cells of yesterday and is now closer in specificationto highly flexible placement machines. Differences exist in thearray of picking, sensing, testing and placing options available,and EOL automation does not need customization or specificsoftware development.
“Flexibility leads to complexity leads to redundancy” is themost usual response to a suggestion that what was primarilyaccomplished manually be automated. While certainly true inthe case of a robotic cell being configured to meet a given prod-uct’s demands, today’s EOL machines no longer center theirtechnologies on robotics systems. Instead, they favor WindowsOS and the generic motion control, vision systems and feedersused by many other SMT machines.
A typical automation cell today is 1 m in length; productivitycan be enhanced through the use of multiple cells in a line. Onecell typically will cover the output of three operators per shift in1/6th of the area required by a manual workforce. We return toour discussion of justification (Table 1).
The tangible and intangible factors are subject to interpreta-tion and investigation, but experience indicates that many com-panies fail to recognize the benefits of EOL automation and theopportunity for efficiency gains.
What payback does automation offer?
• Predictability (no vacations orsick time).
• Greater productivity per unitof space.
• Process repeatability.• Multi-shift ramp with a mini-
mal incremental cost.• Better floor space utilization.• Reduced manual operatives
with their associated highdegrees of variability.
Consequentially:• Quality improvements are expected.• Rework requirements are diminished.• Inventory management is improved.• Actual costs are reduced.• Increases in productivity can be realized instantly.Of course, some obstacles to EOL automation need to be rec-
ognized and addressed prior to implementation. For instance:• Few standards exist for component packaging.• Product design must account for the methodology of auto-
mated assembly. It is not realistic to take a product that pre-sents difficulties to an operator and expect machinery toovercome those issues.
• Incoming materials inspection must be able to pick up vari-ances in batches of materials. Simply accepting variability inthe supply of materials frustrates an otherwise straightfor-ward process.
Cost per placement and actual increases in quality, reductionin labor and floor space are all measurable, and can be quantifiedwith some degree of accuracy to help determine whether an EOLinvestment makes sense.
Allen W. Duck is CEO and president of PMJ USA and Patty Chonis is sales and
marketing manager; [email protected].
Placement / year per Operator or Machine
0
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
14,000,000
Automated in Europe Automated in China Scandinavia Est onia China
Area
Pla
cem
en
t /
yea
r
Placement / year
FIGURE 1: Operators place a fraction of the parts of an automatedsystem.
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
Europe Automated China Au
Cost / placement incl operator
tomated Scandinavia Estonia ChinaArea
EU
RO
Cost / placement incl operator
FIGURE 2: Actual cost per part placed is an extreme unit cost expensecompared with automated alternatives.
Tangible
MaterialsLaborPlant overhead
Intangible
ReworkQuality impactsRework inventory (cash flow)Customer satisfaction
TABLE 1: Tangible andintangible factors affectingCOG.
Cover Story
T here has been much discussion aboutthe merits of lead-free alloys, withtheir physical and electrical proper-
ties being examined – and sometimes dis-puted – in great detail. Whatever the end-user’s preference, one truth remains: thereliability of a lead-free soldered jointshould be at least as good as that achievedwith tin-lead solders.
How does a soldered joint fail? To estab-lish how reliable a lead-free solder is likely tobe in service, first examine the factors thataffect reliability. Consider the mechanism bywhich a soldered joint fails. The typical fail-ure mode for a sound solder joint is lowcycle fatigue (LCF), whereby differentialthermal expansion through temperaturecycling or power cycling continually stressesthe joint until the point of failure. AlthoughLCF failures may have a root cause thatstems from a flaw in the material – brittleintermetallics or excessive voiding, forexample – keep in mind that even a soundjoint has a finite life, and can be expected tofail after a certain number of cycles. Reliabil-ity is measured as cycles to failure.
One might reasonably assume the bulkproperties of a solder alloy are a good indi-cator of its behavior and reliability as a sol-dered joint. If this were the case, lead-free
assemblies should exhibit higher reliabilityfor two reasons. First, their (typically) high-er melting points suggest that any stress gen-erated during service is less likely toapproach the alloy’s yield strength, whichappears to be confirmed by the better LCFproperties of a lead-free alloy in bulk form(Sn-3.5AgCu alloy has been found to besuperior by a factor of ten when testedagainst Sn63Pb at 25°C)1. Second, lead-freealloys possess higher strength, particularlycreep strength.
But the reality is somewhat differentwhen soldered assemblies are actually tested.Despite the lead-free alloy’s superior creepstrength, it shows similar reliability toSn63Pb and Sn62Pb2Ag under fatigue test-ing. Conversely, whereas the addition of bis-muth degrades lead-free performance underisothermal testing of the bulk alloy, theopposite is seen when a board assembledusing Sn3.5AgBi alloy is used. Clearly theisothermal bulk alloy tests are a poor guideto assembly reliability.
Design and Process FactorsTo see the full picture, a wider selection of
factors that affect joint reliability must comeunder scrutiny. These can be grouped intotwo main categories: design factors andprocess factors. The design of the assemblyincludes considerations such as the size andcomposition of the components and PCB,and how the board is populated. These detailshave a bearing on the compliance of the
Research finds bulk alloy properties are not a meaningful predictor of reliability.
Assessing Solder Joint Reliability in Pb-Free AssembliesSteve Dowds
28 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Cover Story
assembly (lower compliance for LCCCsand chip components than for QFPs, forinstance) and determine the pattern ofstress applied to individual joints.
Process factors – variables such as alloycomposition, reflow and cooling profiles,degree of oxidation of component termi-nation and board finish, solder pastecharacteristics and stencil design – influ-ence joint geometry and integrity, anddetermine the likelihood of excessive voidformation or defects occurring at the sol-der/substrate interface. The microstruc-ture of the joint may also be modified bythe dissolution effect of the solder alloyon board and component finishes.
When assessing and comparingresults of reliability tests, the test proce-dure and conditions must be taken intoaccount to avoid misleading or contra-dictory reliability claims through inap-propriate comparison of data. In particu-lar, the criteria that define failure must becarefully chosen. Typical tests include:electrical monitoring, failure beingdeemed to occur when a specified resis-tance is exceeded; measurement of jointstrength – chip component joints at, say,50% of their original strength and QFPleads at 0% could be assessed as failures;and microsectioning joints to monitorcrack development.
Having established the factors thataffect reliability, reviewing some of theacknowledged test regimes and theirresults provides a real-life picture of lead-free reliability. First, examine the reliabili-ty testing conditions used in the IDEALS(Improved Design Life and Environmen-tally Aware Manufacturing of ElectronicAssemblies by Lead-Free Solder) pro-gram, summarized as:
• Thermal shock: -25°/+125°C, 3 min.dwell; -20°/+100°C and -40°/+125°C,30 min. dwell.
• Power cycling: 20-110°C.• Vibration: random 50-2000Hz oscil-
lation, 6-43g acceleration, duration15 min., along x, y and z axes.
• Failure parameters: measure jointstrength of 1206 resistors and micro-section failed joints.
• The 1206 component outline waschosen because it was inexpensiveand available with lead-free termina-
tions. The substrate finish was OSPcopper.
The results show that the shearstrength of Sn96 alloy under temperaturecycling is close to that of Sn62 and Sn63alloys, being reduced about 50% over3,000 cycles.2 Power cycling shows a simi-lar trend, the shear strength of 96SCremaining slightly and consistently belowthat of Sn62 and reducing by about 45%over 3,000 cycles. When sectioned, thefailure mode for the lead-free solder alloyis virtually identical to that for tin-lead,the fracture initiating in the thin layer ofsolder beneath the component and prop-agating through the main bulk of the sol-der fillet (Figures 1 and 2).
Next, the NCMS (National Center forManufacturing Sciences) test regime andresults:
Program 1• Temperature cycling: -55°/+125°C, 20
min. dwells, 11°C/min. (LCCC-44,1206, QFP-132, PLCC-84, immersionSn FR-4 PCB).
• Temperature cycling: 0°/+100°C, 5min. dwell, 10 min. ramp (same com-ponents).
• Failure criterion: continuous electri-cal monitoring – intermittent opencircuit (200Ω).
Program 2• Temperature cycling: -55°/+160°C,
10 min. dwells, 10°C/min. ramp (testcomponents 20-lead LCCC, 1206,0805, 80-lead UTQFP, on OSP FR-4).
• Temperature cycling : -40°/+125°C,15 min. dwells, 15 min. ramps (testcomponents fleXBGA, PBGA, onOSP FR-4).
• Temperature cycling : 0°/+100°C, 5min. dwells, 10 min. ramps (testcomponents fleXBGA, PBGA, onOSP FR-4).
• Failure criterion: continuous electri-cal monitoring – intermittent opencircuit (200Ω).
Looking at the LCCC results for num-ber of cycles to first failure at -55°/+125°C,the Sn43Bi57 alloy offers the best perfor-mance (at close to its melting point of138°C), while other lead-free and SnPballoys exhibit behavior similar to eachother. For the 20-lead LCCCs at -55°/+160°C, the target is to match lead-
30 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Altegra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33www.altegra.com
APEX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37www.GoIPCShows.org
Assembléon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4www.assembleon.com
BEST, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33www.solder.net
Cookson Electronics Assembly Materials . . . . . . . . . . . . . . 22,23www.alphametals.com/lead_free
Digi-Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C2www.digikey.com
Electronic Reprints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [email protected]
Ellsworth Adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3www.ellsworth.com
ESD Association . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Henkel Corporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2www.loctite.com/electronics
HMS Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46www.hmscompounds.com
Indium Corporation of America . . . . . . . . . . . . . . . . . . . . . . . . 33www.indium.com
Kester Solder Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25www.kester.com
KIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26www.kicthermal.com
Metcal/OK International . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C4www.metcal.com
Panasonic Factory Automation. . . . . . . . . . . . . . . . . . . . . . . . . . . 9www.panasonicfa.com
PCB Design Conference West 2005 . . . . . . . . . . . . . . . . . . . . . . 43www.pcbwest.com
PCBRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C3www.pcbrc.om
Phoenix Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15www.phoenixcon.com/thr
Preco Electronics Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29www.preco-morton.com
Samsung Techwin/Dynatech . . . . . . . . . . . . . . . . . . . . . . . . . . . 13www.dynatechSMT.com
SMT/Hybrid Packaging 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . 39www.smt-exhibition.com
Speedline Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19www.speedlinetech.com
ViTechnology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7www.vitechnology.com
View Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17www.vieweng.com
Vitronics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11www.vitronics-soltec.com
Ad IndexADVERTISER INFORMATION: To learn about theadvertisers in this issue, go to circuitsassembly.comand select “Advertiser Information” in the Magazine sec-tion of the home page menu. This will provide you withdirect links to the home or product pages of each adver-tiser in this index.
Company Page No.
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Cover Story
circuitsassembly.com Circuits Assembly DECEMBER 2004 31
free performance to Sn-Pb performance at -40°/+125°C. The bis-muth alloys – SnAg3.4Cu1Bi3.3, SnAg3.3Bi4.8 and SnAg4.6Cu1.6Sb1.0Bi1.0 – come closest but still fall well short of the target,while the best of the SAC alloys manage less than 50% of the SnPbperformance. For fleXBGA at -40°/+125°C, the story is different,with the SAC and SnAgIn alloys narrowly taking the top spots, butwithout significant advantage over other lead-free alloys and SnPb.Under more moderate conditions of 0°/+100°C,bismuth-contain-ing alloys again come to the fore, with SnAg3.4Cu1.0Bi3.3 andSnAg4.6Cu1.6Sb1.0Bi1.0 outperforming Sn63Pb by almost 300%and the best of the SAC alloys by 25%.
These findings raise the question of the effects of regimeseverity upon the results. Take two of the alloys; upon normal-ization the trend is more apparent (Figure 3): at 0°C/+100°C,Sn63Pb exhibits a fatigue life only half that of SnAg3.5; at -40°/+125°C this rises to around 85%; and at -55°/+160°C, itleaps to about 220%.
Confusing and contradictory as these results may appear,the following observations may prove helpful in their interpre-tation:
• Bulk alloy properties, including fatigue and joint strengths,are not a meaningful guide to lead-free reliability perfor-mance.
• High-tin, lead-free solders containing silver, copper, anti-mony and bismuth show broadly similar reliability toSn63Pb37 and Sn62Pb36Ag2.0 solders.
• Different SnAgCu alloys possess similar reliability character-istics.
• SnPb solders exhibit a higher fatigue life than lead-free sol-ders under more extreme conditions (high temperature andstrain ranges).
• Under less extreme conditions (lower temperature andstrain ranges), lead-free solders display up to double thefatigue life of SnPb alloys.
• Accelerated testing at high strain ranges extrapolates differ-ently to less extreme conditions for lead-free and tin-leadalloys.
• Adding up to 5% bismuth may improve reliability, providedthere is no lead contamination that could cause the forma-tion of a low-melting SnPbBi phase.
• As yet, there is no sign of a fatigue-resistant solder, regard-less of alloying additions.
• Solders with melting points (mpt) close to peak tempera-ture during cycling seem to perform particularly well; e.g.,Sn43Bi (mpt 138°C) at -55°/+125°C and Sn63Pb (mpt183°C) at 150-160°C peak.
Research continues, but for now the most reliable choice(while lead can potentially occur anywhere in the assembly)remains one of the SAC alloys. Once lead is eliminated fromboard finishes, components and fittings, the lower meltingpoint and improved wettability of SnAgBi alloys may provepreferable.
References
1. Y. Kariya et al, Journal of Electronic Materials, vol. 27, p. 1229-1235, 1998. 2. M. Harrison, H. Steen and J. Vincent , Soldering & Surface Mount Technolo-
gy, vol. 13, no. 3, p. 21-38.
Steve Dowds is global product manager, Henkel Electronics (henkel.com);
FIGURE 1: Microsectioned SnAgCu solder joint (after 1,000 cyclesbetween -25°/+125°C) showing fracture initiating in solder beneaththe component and extending through the solder fillet.
FIGURE 2: SnAgCu solder joint after 2,000 cycles, showing same fail-ure mode as Pb-free joint in Figure 1.
FIGURE 3: Normalized fatigue life for Sn63Pb37 relative to SnAg, dif-ferent cycling regimes.
Screen Printing
E lectronics manufacturers often use theterms “cycle time” and “throughput”interchangeably. In fact, they are spe-
cific and distinct factors in measuring perfor-mance. Cycle time is the speed at which thebasic functions of a machine can complete thetask of board handling and alignment. Theactual movement of a board in and out of amachine, alignment of the board to someknown target (stencil fiducial mark), move-ment of the board to its required position andits transport to the downstream process aretypical cycle-time specifications. The actualcompletion of the primary function of thatmachine – in this case, the printing of solderpaste – is generally additive to the acceptedelements that define machine cycle time.
The printer supplier will often define cycletime as the period during which a circuitboard travels in and out of the machine andalignment of the board to a known target.Generally, the actual print stroke is notincluded in the printer supplier’s cycle-timeequipment specification. The print stroke istied to the particular solder paste used and thesize of the substrate produced. Most printerstoday can move a squeegee much faster thaneven the fastest-printing pastes. Many compa-nies use pastes that must be printed slowly bytoday’s standards and often are the major time
factor in printing cycle time. Given the impactof variables driven by materials, equipmentmanufacturers have scaled back the cycle-timedefinition to items under their control.
We should also consider a broader defini-tion of machine cycle time to better under-stand machine throughput and equipmentutilization. The broader definition wouldinclude all the functions described above plusthe overhead functions the machine can per-form. Overhead functions are those that themachine can perform that are not directlyinvolved in the actual operation of transport-ing and printing paste onto the board. Mostmodern printers can perform a number ofoverhead functions, such as: stencil cleaning,2-D post-print inspection and material dis-pense onto the stencil. Some advanced sys-tems offer 3-D post-print inspection of thepaste deposit, slow snap-off, installation ofsupport pins, SPC collection and other man-agement and quality data as additional capa-bilities to improve machine yield. Comparingprinters is difficult when considering thisexpanded definition of machine cycle time,since these items displace manual or offlinefunctions the manufacturer conducts toensure process quality. True assessment ofmachine performance requires a full under-standing of how each specific overhead func-tion performs its tasks. The speed at which themachine can perform the overhead task is cer-tainly one major consideration. However, so ishow accurately and repeatably the machineperforms the overhead operation.
Is the best indicator of performancemachine cycle time, or first-pass yield?
Throughput vs. Cycle Time in Evaluating Paste PrintingJoe Belmonte and Bob Boyes
32 Circuits Assembly DECEMBER 2004 circuitsassembly.com
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HOW DO YOUR CUSTOMERSRATE YOUR SERVICE?Enter the 2005 Circuits Assembly ServiceExcellence Awards and find out your cus-tomers’ honest opinions about your prod-ucts and customer service.
On October 1st, Circuits Assembly willbegin accepting entries for the 13th annualService Excellence Awards—the ONLYawards program judged by the people whomatter—YOUR CUSTOMERS.
Entry and Program RequirementsThe Service Excellence Awards are opento EMS providers and electronics assemblysuppliers (equipment, materials and soft-ware). You provide a list of your best cus-tomers, and a third-party research firm willgather customer feedback to determinetheir level of satisfaction. The highest-rank-ing companies will be presented withawards at APEX 2005!
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Screen Printing
One recent printer innovation is the capability to performsome overhead functions in parallel, resulting in no actualthroughput penalty for the additional capability. The machinethat performs two or more overhead functions in parallel andstill provides best-in-class accuracy and repeatability will like-ly show the fastest machine cycle time, using this expandeddefinition.
Throughput is a measure of how many “good” board assem-blies can be produced in a given time period. While machinecycle time is an important initial indicator of a machine’s per-formance, it is critical to understand overall throughput as thekey metric in evaluating process equipment. One importantmetric for any electronics manufacturing operation is, howmany boards were built today that can be shipped to customers?A good assembly is a unit that passes all board and functionaltests on the first try (first-pass yield), without touch-up orrepair. To the extent that a printer exceeds the throughputrequirements for a line, other utilities such as increasing stencil-wiping frequency, reducing snap-off speed or increasing criticalcomponent inspection, can be used to favorably impact yieldperformance. Manufacturers make money on building goodboards, not on owning fast machines. When we considerthroughput we must consider many more factors then just basemachine cycle time.
A side-by-side evaluation was run between two printersusing identical boards and product process parameters. Bothmachines had identical published specifications for cycle time,so if all other things remained equal, using cycle time as themeasure could suggest that the two machines would deliverequal boards per hour. As Figures 1 and 2 show, while the basemachine cycle times were equal, there was a 5% difference inaverage printing throughput time. Further, use of overheadfunctions such as stencil cleaning or 2-D post-print sampleinspection options within the printer can result in a differenceof more than 25% (Figure 3). Given equivalent yield perfor-mance, printer A in this study clearly provides a much greaterthroughput in terms of boards/panels per hour. The machinethat can perform overhead functions faster permits additionalprocess control and monitoring, effectively increases yield – thetrue definition of throughput.
Throughput VariablesTo effectively evaluate the actual throughput of a printer the
following variables must be taken into account:• Cycle time, measured as board transport into the machine,
alignment, delivery to the print height, return to transport heightand exit from the machine (not including the print stroke).
• Print stroke parameters. These consist of applied force,squeegee travel and speed parameters. These are affected byboard size, component density, component pitch and paste com-position (a notable variable because different rheology typicallymeans different speeds).
Optimizing solder paste printing cycle time requires the useof fast-printing paste. The larger the board, the more critical theactual print stroke is in contributing to cycle time. If a 12" board
is being processed with a paste that can be printed at only 2" persecond, then the print stroke is 6 sec. The print stroke can beshortened to 1.5 sec. if a solder paste that can be printed at 8" persec. is used.
• Whether squeegees or an enclosed print head are used.Enclosed print heads eliminate the time required to replenishsolder paste on the stencil. Even if an automatic paste dispens-ing system is used, the machine must take some time to depositnew paste onto the stencil. The enclosed print head offers aunique advantage when changing over the printing require-ment from one product to another. All the solder paste is nowin the enclosed print head. Very little paste has to be scrapedoff the stencil prior to cleaning it. Less solder paste is wastedbecause the paste for the next product is already in theenclosed print head.
• Paste application. If squeegees are used, how is the pastedelivered to the stencil? Some factors include the method (man-ual or automated dispenser), the aperture density and size of thePCB, as this will determine the frequency of replenishmentrequired.
• Operating software ease of use. The software must be sim-ple for an operator to use. All functions that an operator can con-trol must be easily understood and accessible. Should be as intu-itive and simple to use as possible. This facilitates setup,changeover and operation of the machine, which contribute tothe long-term production output of the system.
• Stencil cleaning frequency and method. All solder pasteprinting processes require the stencil to be cleaned at some fre-quency. How often a stencil requires wiping is a function of sev-
34 Circuits Assembly DECEMBER 2004 circuitsassembly.com
0
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Run 1 Run 2 Run 3 Run 4 Run 5 Average
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Advertised cycle time for both machinesThroughput with 2-D Printer AThroughput with 2-D Printer B
FIGURE 1: Throughput vs. cycle time with 2-D post-print inspection.
0
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Base + print Base, print & wipe Base, print 2-D
Printer 1 Printer 2
FIGURE 2: Cycle time and throughput for two printers.
Screen Printing
circuitsassembly.com Circuits Assembly DECEMBER 2004 35
eral variables including stencil design, board final finish andboard support during printing. Since stencil cleaning is a mustfor even the best-designed printing process, we must evaluatehow a particular machine performs this function. All modernsolder paste printing equipment offers stencil cleaning capabili-ty. How the stencil cleaning function is performed must beunderstood; for example, were a vacuum and solvent employedto assist the cleaning?
• Stencil-to-board snap-off distance and speed. All systemsdo not operate the same, and due to higher densities, some PCBsrequire slower separation speeds to improve paste deposit sepa-ration from the stencil.
• Post-print inspection. Most printers offer 2-D post-printinspection, and some offer 3-D post-print inspection of pastedeposits of critical devices. 2-D and 3-D post-print inspectionsystems do not operate in the same way, and understanding whatvariables can be measured, the method and how the resultantdata are used is essential to assessing the value of this additionaloperation.
• Setup and changeover solutions, including the associatedMTTA. The majority of paste printing operations require prod-uct changeovers. Many operations change several times in oneday. How quickly your equipment can be changed from oneproduct to the next must be understood. What productchangeover variables can a particular machine optimize?
• Process control. As discussed, throughput is a measure-ment of how many good assemblies can be produced in a par-ticular time period. The quality of what we are building is crit-ical to achieving maximum throughput. We must understandhow our process is operating in as close to real time as possi-ble. We cannot optimize throughput by finding defects at theend of a product run. We must have a proactive manufacturingculture that will prevent defects, not a reactive manufacturingculture designed to find defects. The key to a proactive manu-facturing culture is a well-designed and well-executed statisti-cal process control (SPC) program. What features of solderpaste printing equipment can assist in the implementation of aSPC program?
• Operator training and discipline. A well-trained, disci-plined, conscientious operator will be a major contributor topaste printing process performance. Operator training must gobeyond basic machine operation. The operator must understandeach factor that contributes to process performance and how itimpacts all processes in manufacturing, including final productquality. Training is vital, but process discipline is just as impor-tant. Operators must perform their jobs the same way all thetime, on every shift. Supervisors and support personnel musthelp operators understand and follow procedures.
• Process optimization (stencil design, operating parameteroptimization, etc.). Process optimization is the means by whichengineers and operators understand, identify and quantify allvariables that influence the performance of the actual printing ofsolder paste, and use that knowledge to improve the process.Operating parameters such as squeegee speed, applied force,down stop and print stroke length must be quantified and opti-
mized using formal statistically valid studies such as design ofexperiments (DoE). Other factors to consider are stencil design,board design and finish, board support and solder paste selec-tion. The print process is often identified as a major defect sourcein the line; however, the hardware itself is only one portion of theequation. Even the best hardware can be overcome if the processis not optimized or incoming materials are not suitable.
• Equipment maintenance. One important aspect ofthroughput is machine uptime (or downtime). Fast cycle time isof little value if the machine requires a great deal of attention tokeep it operational. Obtaining the best possible results requires astrict preventative maintenance (PM) program. Maintenancemust be scheduled at regular intervals, as required. This is one ofthe most neglected areas. Users should develop a clearly docu-mented PM schedule and equipment should be accessible. Com-pletion of the required preventative maintenance should neverbe compromised. The equipment owner should monitor thedata on the performance of their entire process to identify anyadditions or subtractions from the PM schedule. Some adjust-ments to the supplier’s recommended PM program may berequired by a particular process or for a particular PCB design.
While machine cycle-time specifications are usually available,documenting throughput is more difficult as many of the vari-ables are not controlled directly by the printer. It is important towork with the supplier to isolate key attributes and optimizeequipment parameters.
Optimizing process throughput starts with printing equipmentthat provides features that maximize the variables that the equip-ment can control. The combination of all these variables drivesprinter throughput. When evaluating printers, look beyondmachine cycle time and understand each throughput variable thatthe equipment (and supplier) can help optimize.
Joe Belmonte is product manager at Speedline Technologies (speedlinetech
.com), [email protected]. Bob Boyes is MPM product manager,
Cumulative Boards Printed
0
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ard
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FIGURE 3: Printer throughput in terms of serial vs. parallel axisfunction.
Process Control
Q uick Response Manufacturing (QRM)enables organizations to meet customerdemand quickly, permitting businesses to
continually evaluate and react to competitivepressures. QRM eliminates non-value addedactivities and waste through continual reductionof lead times within the supply chain and manu-facturing process.
In 1903, Ford Motor Co. began mass produc-ing automobiles. Cars were available only in blackand lead time was measured in weeks. Today, cus-tomers demand variety and lead time is measuredin minutes. Yet as time from concept to mass pro-duction for new products shrinks, so does profitmargin. QRM is a way to increase customer satis-
faction while improving the returns of the orga-nization (Figure 1).
Historically, businesses build redundancy with-in internal processes and supply chains for safetymeasures. This results in wasted time andresources. Material within the supply chain canquickly depreciate or even become obsolete. Thechallenge is to be more responsive to customerneeds and increase flexibility while reducing inven-tory and waste.
QRM also requires a shift in company culture.Historically, a fixed manufacturing schedule wasthe norm; today it is virtually nonexistent. QRMsystems support lead-time reduction, reducereliance on forecasts, increase responsiveness tomarket demands and ultimately contribute to theprofitability of the organization.
Here are QRM’s key benefits.• Concurrent and time-compressed process-
es. Defining product and process data at the sametime the product is being designed permits fasternew product introduction. By using an open pro-gramming system that imports CAD and BOMfiles, design data can be easily inspected and vali-dated against current processes. This is furthersimplified by using centralized management ofpart number and component libraries enablingconsistent product and process data.
A good example of software’s capabilities topermit high-quality products to be defined andbuilt is placement equipment. Effective NPIprocesses quickly turn incoming data and materi-als into finished product with little-to-no waste,errors or scrap. The benchmark for NPI is com-plete offline simulation prior to new model intro-ductions. This permits the production line to focuson running production jobs instead of being usedfor (expensive) debugging and programming.
Still using your pick-and-place fordebugging? Tools for surviving a zero-forecast world.
Enabling Quick Response ManufacturingDoug Johnson and Vern Harrison
36 Circuits Assembly DECEMBER 2004 circuitsassembly.com
FIGURE 1: Quick Response Manufacturing cuts lead time andimproves responsiveness, leading to better profits.
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Process Control
Debugging on the placement system reflects a failure to meetexpectations and results in waste as well as increased responsetime. Tying up the production line to resolve NPI issues addsuncertainty to fulfillment schedules. If a company’s central NPIdepartment exports data to multiple production lines, or if facili-ties have suspect, non-validated or incorrect data, the entire enter-prise may be put at risk. A central NPI department requires feed-back from all customers to ensure that common problems areresolved in the source data. Using a single database with consoli-dated manufacturing and product data components reduces thedependency on informal communication.
A second benchmark for NPI is showing the CAD location ofthe components graphically on a scanned image of a bare PCB.This placement simulation permits complete first-article verifica-tion at the programmer level, where modifications can be easilymade. This process eliminates the need for tape or trial builds.Feeder setup sheets that include a graphical depiction of the com-ponent and its orientation, coupled with user validation, enableflawless definition and execution of setups.
Although implementation of QRM processes requires recon-sideration of the entire NPI process, using concurrent and time-compressed processes increases machine utilization and reducesNPI time.
• Flexible manufacturing processes. Common lead-timereduction methods include the standardization of tools andprocesses to enable product portability and to provide addition-al schedule flexibility. When the definition is centered on theproduct itself (as opposed to preparing machine-specific pro-grams), the movement of products from line to line or fromfacility to facility is easily accomplished. Common modularmachine elements such as feeders, programming and similaroperational aspects permit workcells to become product-orient-ed and staff to control the activity at the cell level (Figure 2).
• Accurate and detailed scheduling. The ability to evaluateproduction demands quickly and accurately against resourcerequirements – including material availability, system capabili-ties and human resources – needs to be constantly analyzed. Thiscontinual analysis improves accuracy and reduces deviations inthe expected production plan. Less time spent reacting to missedproduction plans means more time for building product.
• Reducing setup time and use of group technology. Setupand changeover activities in a high-mix environment can be thepredominant workload and a large contributor to lead time.Software tools that apply group technology in planning to reducesetup activities and to meet operational scenarios, including“what if” and “delta setups,” can manage and reduce setup work-load. Coupled with well-conceived hardware and software toenable offline setup, and rapid tooling and setup changeover, it ispossible to conduct concurrent activities.
The best setup changeover, of course, is no changeover, butminimizing setup time permits frequent model changes. By man-aging the setup activity, it becomes practical to build products ondemand, to achieve small WIP inventories. This practice is alsoknown as Heijunka, or production leveling. Frequent modelchanges reduce WIP, as well as embedding the ability to support
quicker responses into the system. QRM focuses on the customer’sspecific needs and not on production for production’s sake.
• Process analysis to identify NVA activities. The QRM envi-ronment mandates making decisions with accurate and currentinformation. Time delays associated with manually collecting,formatting and distributing reports may result in decisions thathurt lead time. Real-time information supports real-time reac-tions and adjustments.
It is important to comprehend the commitments of the pro-duction system, the progress that the system is making and thesystem’s capability to engage new tasks to meet customerdemands. Up-to-date information provided by the system tosupport other business systems may include: unit completions,lot status, material consumption and attrition, and replenish-ment notifications.
• User-targeted tools and technology. Technology, includingIT integration, is intended to inform and empower users, wherev-er they may be or whatever they do. The capability to tailor infor-mation to users’ needs, as well as provide the information whereand when the user needs it, can save time and improve user effec-tiveness. User-customized report content and presentation canenhance performance. Real-time alerts and alarms can enhanceresponsiveness. Visibility wherever the user may be, including thefactory floor, enables quick response. What should happen nextbecomes obvious for all participants within the manufacturingorganization. QRM enables organizations to quickly meet cus-tomer demands by requiring constant evaluation and response.
Yet agile systems that support QRM are only a part of thesolution. Leadership and change within each company willdetermine the effectiveness of the QRM initiative. A companydriven to embrace rapid planning and execution as core princi-ples will gain a competitive advantage.
Doug Johnson is software product manager at Siemens Logistics and Assembly
Systems (logistics-assembly.siemens.com); [email protected]. Vern
Harrison is software product manager; [email protected].
38 Circuits Assembly DECEMBER 2004 circuitsassembly.com
FIGURE 2: Common and modular machine elements, such as feedersand programming, make workcells product-oriented and permit staffto control activity at the cell level.
Information: Phone +49 711 61946-74 or [email protected]
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Parts Management
C reating part data libraries for placementmachines is a daunting task that can be time-consuming, error-prone and labor intensive.
Coupled with a multi-vendor line, in which eachmachine is programmed by different software (eachwith its own part data definition), the result is a cost-ly and tedious process.
Assembly machines require certain parameters tohandle parts. They include a geometric representationof the part and handling instructions, some of whichmay be derived from the geometry. Such informationcurrently comes from data sheets or physical measure-ments. The manual definition process is tedious, withno checks to ensure accuracy. Imagine an SMT pro-grammer breaking apart a single lead of a $300, 144-lead QFP IC to measure its width with a caliper(Vernier), because the lead couldn’t be measured in situ.In addition to being a waste of money, the measurementis probably inaccurate. Or picture an expensive SMTline left idle for 15 or 30 minutes because a part cannotbe placed and part data need to be reprogrammed.
Machine part data consist of a geometric descrip-tion of a component (length, width, number of leads,etc.) and various handling parameters (nozzle, camera,lighting, etc.). Manual entry of geometric data involvesslow and inaccurate measurement methods andnumerous searches of part data sheets. Automatic gen-eration of machine language geometry fields from thelibraries is fast, accurate and efficient.
To understand the nature of manual part handlingdata definition, consider: One of the handling parame-ters for parts is the nozzle size most appropriate to pickit up. With manual definition, operators memorize the
table of conversions of package size to nozzle. Acquir-ing this knowledge is a bottleneck in their training andthe source of human error, resulting in wrong picksand placements. Conversely, an automatic processbased on electronic libraries applies a formula to cal-culate nozzle size automatically and repeatably.
Libraries containing accurate geometric descrip-tions for most parts in use today are available. Specif-ic machine format geometry can be derived fromthese descriptions. Other parameters can be deducedusing rules. Part data creation becomes quick, accu-rate, reliable and automatic. Automatically createdrotation orientation standardized part data improvesand speeds up NPI processes. Adding virtual proto-typing streamlines the process so that new productsetup no longer requires skilled labor, eliminating lossof machine time or material (Figure 1).
Virtual prototyping removes the need for physicalmachine program verification onto double-sidedsticky tape, which is costly in terms of line productiontime and scrap. Virtual prototyping is a programmaticmethod displaying a simulated populated board usingthe geometry and rotation of the machine part library.The simulation uses actual machine part data andmachine programs to verify the accuracy of the datawithout using actual boards, parts or lines.
Libraries alone cannot do the trick. There must alsobe tools that use libraries. The most important is a com-mon programming platform for all machines on theshop floor.Assemblers have come to rely upon a hetero-geneous mix of machines, yet most suppliers’ program-ming solutions fall apart in a multi-vendor line or fac-tory. Independent software providers create softwaresolutions capable of programming a heterogeneous lineusing similar tools and a common look and feel. Thesetools not only use part libraries from all vendors andmachines, but also reduce operation costs through bet-ter line balancing, easier operator training and addi-
Intelligent, centralized machine partdata management cuts human error.
Programming for Mixed-Vendor LinesBini Elhanan
40 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Parts Management
circuitsassembly.com Circuits Assembly DECEMBER 2004 41
tional capabilities (such as reduction of feeder setup time throughcalculated “grouping”1 of products in high mix environments).
Physical part libraries are also used in a variety of tasksbeyond creation and management of placement equipment partsdata. Additional capabilities include:
• Analysis of BOMs and AVLs to eliminate erroneous alter-nate parts, saving hours of line downtime if an error goes unde-tected until production begins.
• Automatic creation of AOI machine part libraries that canprevent expensive machine downtime.
• Faster and more accurate fixture design.• DfA and DfT analysis to detect part placement, solderabili-
ty and testability problems long before they cause harm onthe shop floor or, worse still, in a delivered product.
• Creation of better shop floor documentation.The lack of central, multi-vendor, library-based parts data
control systems causes such part data to be managed on the fac-tory floor sporadically at line computers or the individualmachine. This chaotic approach of manual data creation andmaintenance is labor intensive and often inaccurate.
The absence of centrally managed part data leads to multiple,differing representations of the same parts on individual machines.This can lead to inconsistency, out-of-control situations and loss oftime due to multiple machine-learn cycles for the same part.
Indeed, it is very common to find the same shape in a machinelibrary in many different guises; e.g., 0805, 0805-1, 0805Fred,0805_1. Technicians resort to redefining parts because they lackthe tools to look for existing definitions. Not only is time lost tomachine setup, but machines are underutilized because of less-than-optimal operational speed setting in the parts data.
Further inefficiencies arise in the following areas:• Technician time is lost searching for data sheets and mea-
suring parts using a Vernier.• When a new product is run it can take in excess of 3 hours
(depending upon the quantity of new shapes) to programand teach the shapes. This is not only costly in manpower,but the line is unproductive during this period.
• It is time consuming to move a program from one manu-facturing line to another as a result of inconsistencies in themanagement of part data on different lines. Long delaysresult as the operator ensures that the program referencesthe correct parts on the new line.
The NPI process to get the first board from the line is far toolong, given these inefficient practices. With a more efficient NPIprocess, prototype boards are assembled quickly and time-to-market is reduced.
Translating the list of problematic issues into numbers helpsto calculate return on investment for the implementation ofintelligent part libraries. Assuming:
1. An average line generates $50 million in revenue a year. Itshourly profit is $250, assuming a 4% margin.
2. ROI will be calculated for a 10-line plant.3. Thirty new jobs are introduced every week.4. NPI setup time on the line is reduced by 50%, from 5 hours
to 2.5 hours.The savings for reducing NPI time alone is
30 (jobs per week) * 50 (weeks per year) * 2.5 hours per job* $250 per hour = $937,500 per year.
Automatic generation of accurate and reliable part data fromintelligent part libraries, along with a common multi-vendorprogramming platform, provides a watershed solution. Opera-tors need only be trained on one tool. Full realization of line bal-ancing capabilities is possible as the task of defining part data forall applicable machines is no longer a bottleneck. Streamlinedpre-production engineering becomes a reality. Further savingscan be realized through improved operational efficiencies andline throughput.
Reference
1. “Grouping” of products is a process by which a significant number of differ-ent products that need to be assembled in small quantities in a given periodare separated to groups sharing a common feeder setup. This processimproves line uptime significantly by eliminating the need to change thefeeder setup on a per product basis.
Bini Elhanan is director of technology at Valor Computerized Systems
(valor.com); [email protected].
FIGURE 1: Manual operations (at left) rely on training operators,which is labor intensive and error-prone. Automation (right) offers arepeatable and centrally managed process.
ProductSPOTLIGHT
42 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Assembly EngineeringTool
Trilogy 7.3 features line balancer, to speci-fy which machines participate in balancing,and global panel fiducial capability. Permitsuser-defined labels to be added to compo-nents, prevents empty feeder slots from hav-ing parts assigned and has new componentextraction capabilities. Supports additionalSiemens and Panasonic lines.Valor Computerized Systems, valor.com
Chip Tube CartsChip tube carts are ergonomically designed
for storage and positioning. Steel construc-tion, with four bin rows that can be subdivid-ed on 0.50" centers. Using available slide-individers, rows can be configured in varioussizes. Presentation angle of the storage binscan be adjusted for operator comfort duringmanual component assembly. Includes built-in ESD protection and adjustable height viagas springs.Bliss Industries, blissindustries.com
3-Gantry Pick-and-PlaceSiplace HF/3 reportedly places parts at up
to 40,000 cph with accuracy of 30 µm at 4sigma, and has 180 feeder inputs and acomponent range from 0201s to 8" connec-tors. Has a three-gantry parallel placement,for speed and flexibility. Linear motors on allaxes for acceleration and deceleration;extra-stiff carbon-fiber gantries permit hightravel speed. New camera system for com-ponent recognition and placement ofCCGAs and BGAs.Siemens Logistics and Assembly Systems,siplace.com
2-Sided Thermal PrinterT612M-DS double-sided thermal transfer
printer can simultaneously print on the frontand back of the marker. Can process all TMSSystem SIX heat-shrinkable markers, from2.4 to 57.2 mm. Rated for heavy-duty cycles,incorporates a 300-dpi (12-dpmm) printhead. Data printed onto the two sides of eachmarker can be identical, different, same-sideup or flipped. Nominal print speeds of 50 to128 mm/sec.Tyco Electronics, tycoelectronics.com
Spray FluxerOptima spray fluxer is said to improve flux deposition and
through-hole penetration while eliminating post-wave fluxresidue. Reportedly sprays a precise, rectangular pattern andmaintains head speed and position control. Setup parametersare controlled electronically and password-protected. Operatorinterface stores hundreds of recipes. Dual-flux tank option forrapid change between flux types. Can be retrofitted to anywave-solder machine.Ultrasonic Systems, ultraspray.com
User Interface UpgradeInstinctiv user interface acts as the portal to technical support
services via the Internet and now comes on the Micron-classGalaxy and Europa platforms. Displays machine and process datain an easily digestible form. Features advanced graphical tech-niques, real-time indication of consumables levels and on-boardhelp and error recovery.DEK, dek.com
Pb-Free PasteAlpha OM-325 lead-free solder is said to simplify the transi-
tion to fine feature printing in lead-free processes. Reportedlyoffers print transfer efficiency, self-alignment properties withsmall components (0402 or 01005), joint cosmetics across chal-lenging reflow profiles, low voiding performance and productstability. Made with Type 4 and 5 powder, works in high-soakreflow profiles.Cookson Electronics Assembly Materials, alphametals.com
High-Mix Pick-and-PlaceFLX2010 SMD pick-and-place has 190 feeders and can place
5,000 cph. Places 0201s and 0.3-mm components, condensatorsup to 15 mm, large connectors and 50-mm BGAs. Features laserand vision centering systems. Feeder management system auto-matically recognizes feeders and pickup height. Setup control sys-tem based on barcode identification. Can be expanded to a two-or three-module production line for more feeder capacity (up to300 feeders) and production speed (up to 15,000 cph).Essemtec, essemtec-usa.com
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Remote Diagnostics SoftwareRemoteTech diagnostics permits remote diagnoses of equip-
ment and application problems. Improves troubleshooting andproblem-solving over the Internet and telephone, minimizing fieldservice visits and cutting mean time to repair. Provides equipmentrecipe files and error logs for software upgrade uploading.Speedline Technologies, speedlinetech.com
ProductSPOTLIGHT
44 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Desktop AOI VerificationScanPoint DT desktop inspection tool is for
traditional, first-article and statistical qualityverification. Inspects for solder paste deposi-tion, placement errors and solder faults.Uses dual lighting to optimize image quali-ty. Windows based.DiagnoSys Systems, diagnosys-usa.com
Stencil CutterLS 800F cuts one to 10 holes/sec. (or 36,000
apertures/hr.), reportedly without heat dam-age, burrs or oxidation. Uses a fiber lasersource for thin, precision stencils and masks.Fiber lasers have high pulse-to-pulse stabilityand are compact, robust and maintenance-free. Said to offer a fine cut, higher cuttingspeed and a higher accuracy than convention-al lasers. 100 µm fiber core diameter enablesusers to apply water jets below 30 µm.Synova S.A., synovia.ch
Pb-Free Wave Solder Flux270WR VOC-free, no-clean liquid flux fits a
variety of process parameters and applica-tions, including Pb-free wave soldering withtin-silver-copper, tin-silver, tin-copper andother alloys. Reportedly offers a broad activa-tion range, good barrel fill, bright and shinysolder joints and solderability even to difficult-to-wet materials. Has ultra-low post-processresidues. Said to be a drop-in for alcohol-based fluxes; non-hazardous. Reduces fluxusage, wave soldering defect levels and pre-ventative maintenance requirements forspray fluxing applications.AIM, aimsolder.com
Stainless Steel ConveyorFully rated for product washdown, convey-
or has side frames built in 304 polishedstainless steel. Can be wet-cleaned afterproduction runs. Corrosion-resistant con-struction said to reduce wear and tear andextend conveyor component life. Offersstyles for zero-pressure accumulation, trans-portation, incline, decline and metering.Uses modular plastic belt conveying surface,eliminating the need for rollers. Operates atup to 300 ft./min., and has a live loadweight capacity of 70 lb./ft.FKI Logistex, fkilogistex.com
Water-Soluble Pb-Free SolderIndium3.1 water-soluble Pb-free solder paste is formulated for
fine-pitch applications. Said to exhibit excellent wetting underboth air and nitrogen reflow atmosphere. Features a wide reflowwindow, slump resistance, low voiding and low foaming.Indium Corp., indium.com
Humidity-Resistant SolderMulticore MP218, a halide-free, no-clean solder paste, is pin-
testable; said to exhibit high resistance to humidity. After 24 hrs.at 75% RH, achieves a high degree of coalescence upon reflowand slump resistance. High tack life results in low paste wastageand initial tack force of 1.6g/mm2 decreases component move-ment during high-speed placement. Suitable for reflow in air ornitrogen, leaves colorless post-reflow residues for visual inspec-tion. Available in Sn62, Sn63 and 63S4 alloys.Henkel Electronics, henkel.com/electronics
Combination TesterHAL Combi combination tester performs all standard electrical
safety tests, permits full traceability of test results and records viainternal data memory storage. Performs earth ground, AC/DC hipot and insulation testing. Tests can be applied individually or inset automatic sequences for repetitive multi-test routines. Testspecs configured into the tester by scanning in pre-defined barcodes. Has selectable 50- or 60-Hz output frequencies, incorpo-rates a 30A constant current low voltage ground bond test.Includes a large high-contrast bar graph display of the mOhmvalue from 0 to 1000.Clare Instruments U.S., clareinstruments.com
‘All Fluids’ Dispensing ValveTS5622VU-DVD dispenses low- to medium-viscosity fluids,
delivers consistent deposits at high speed over a range of shotand bead sizes, and reduces turbulence to counteract air bubbles.Reportedly accurate to a fraction of a microliter. Stainless steelfluid housing ensures compatibility with a variety of chemicals,including UV cure adhesives, resins and lacquers. Short openingstroke provides a fast and positive shut-off, external stroke con-trol adjustment fine-tunes shot size. Weight (0.268 lb.) anddesign (1.06" diameter x 3.45" long) permits mounting flexibili-ty. Operates up to 400 cycles/min.Techcon Systems, techconsystems.com
JTAG/Boundary Scan SoftwareCascon v. 4.1.2 integrated boundary scan development envi-
ronment now interfaces with external software components.Fully integrated application programming extends test coverageof other test platforms and integrates execution, debug anddiagnostics tools. Offers several access levels with over 80 func-tions, can be used with nearly all programming languages andtest executive packages. Backwards compatible, supports con-trollers based on VXI, PXI, PCI, USB, GPIB, parallel port, RS232and fast ethernet.Göpel Electronic, goepel.com
Color Vision SensorsIn-Sight 5100C color vision sensors verify the position of color
LEDs at electrical testers. In-Sight 5101 high-resolution (1024 x768) industrial-grade vision sensor is for gauging applicationsthat inspect small objects, or capturing images of larger parts.Meet IEC specifications for shock and vibration, IP67 (NEMA 6)-rated for dust and wash-down.Cognex Corp., cognex.com
ProductSPOTLIGHT
circuitsassembly.com Circuits Assembly DECEMBER 2004 45
Handheld AdhesiveDispenser
Mixpac handheld cartridge dispenser fortwo-component adhesives consists of a man-ual or pneumatic dispensing gun, cartridgeand static mixer. Can accommodate volumet-ric ratios such as system 50, system 200 andsystem 400. Molded of durable polypropy-lene, uses twist-and-lock static mixers.ConProTec, mixpacusa.com
Transparent EncapsulantOptiClear low modulus, one-component
liquid encapsulant protects light-dependentdevices without interfering with their lightreception features. Transparent and UV orthermally curable, encapsulates electroniccomponents in digital cameras, LEDs andoptical sensors. Cures faster than acrylate-based encapsulants, cures in thin and thickapplications and is odorless. Will fully cureeven under partial UV exposure. Available inthree viscosity levels.Polysciences Inc., polysciences.com
High-Speed SOC Tester93000 SOC series for functional, at-speed
tester is for high-pin-count devices (PCchipsets up to 3.6 Gb/s). Digital card offersper-pin scalability from 800 Mb/s to 3.6Gb/s. Each pin offers both single-ended anddifferential I/O test capabilities to test inter-faces including DDR, G-DDR, PCI Express, S-ATA, HyperTransport and Front Side Bus. Dif-ferential pin edge placement accuracy ofbetter than ±30 ps. Up to eight independentclock domains, can satisfy timing needs forconcurrent at-speed testing of multiplebuses running at non-friendly speed ratios(bus fractions).Agilent Technologies, agilent.com
Coating for SqueegeesSqueegees now available with the entire
blade coated with Permalex. Reportedlyreduces solder paste sticking. Infuses theblade with a polymer lubricant, developedthrough a multi-step metallurgical bondingprocess. Said to reduce stencil pulling andstretching, improving pad registration andstencil life.Transition Automation Inc.,transitionautomation.com
ESD for Wheels/FloorsCaster Cleaner said to reduce ESD risks caused by ungrounded
carts. Enhances wheel performance by continually cleaning thewheel, reducing the build-up of dirt, wax and residue. Extends lifeof floor finishes. Provides electrical path from wheel to stem ofcaster, bypassing potentially insulative grease in caster bearingsand wheel bushings that may cause an unreliable path to ground.Static-Dynamics, static-dynamics.com
ProductSPOTLIGHT
46 Circuits Assembly DECEMBER 2004 circuitsassembly.com
Inspection SoftwareUpdate
Graphical User Interface (FGUI) software
version 2.2 offers real-time background sub-
traction. Background subtraction reduces
shading in x-ray imagery that limits image
contrast. New capabilities include an AVI
recorder, 16-bit image processing, integration
of Direct Digital Detectors (DDD) and image
saving in a variety of formats (e.g., TIF, BMP
and JPG). New image-processing operators
have also been added.
FeinFocus, feinfocus.com
Design and SimulationSoftware
Multisim 8 optimizes repetitive capture
tasks, and is said to provide almost 50%
time savings over previous version. Includes
real Virtual Instruments from Tektronix,
allowing circuit validation and optimization
during schematic entry. An unlimited number
of probes can be placed on the schematic to
annotate a circuit with real-time, dynamic
values such as current and voltage. Users can
configure, save and reuse complete SPICE
simulation parameter setups. Notes can be
attached to any point in the circuit.
Electronics Workbench,
electronicsworkbench.com
Passive Thick FilmAttenuator
IMA303 surface-mount, thick film “T” pad
attenuator is suited for RF and microwave
applications. Operational to 4 GHz, available
from 1 to 20 dB in 1-dB steps. Power handling
on input is 2W. Comprised of a 0.145" x
0.122" x 0.020" alumina substrate. Imped-
ance is 50Ω on input and output with aVSWR
of 1.25:1 at dc to 4 GHz.
International Manufacturing Services
Inc. (IMS), ims-resistors.com
One-Step Hand CleaningGlobalTech saturated disposable wipes remove dirt, oil, grease
and common contaminants from hands, tools and other surfaces.Have a chelating agent, to remove lead and toxic metal residuesfrom skin and other surfaces. Waterless, citrus-scented. Leave noresidue. Will not scratch glass, acrylics, plastics, metal or othercomposite materials.JNJ Industries, jnj-industries.com
HMS-1000C is bulk conductivestyrenic alloy film, roll stock, and sheet used to package electronicsworldwide. HMS-1013C* Carrier Tapeis used to package components forcircuit boards. HMS-1060C roll stockmakes packages for circuit boards anddisc drive components. HMS-1180Csheet makes shipping boxes forboards and sub-assemblies.
DEPENDABLE ESD protection iscompounded into bulk conductiveHMS-1000C packaging stock, unlikecoated packaging stock where staticremains on the surface. Howconductive? About one mega-ohm,like a wrist strap.
TOUGH & SOFT HMS-1000C makesdurable, gentle, and attractively glossypackages for delicate electronics.
Exceptional thermoformability,maximum ESD/mechanical protection,availability, and low cost makeHMS-1000C the ESD tray material.
*HMS-1013C is 0.013" thick, e.g.
HMS COMPOUNDS, [email protected] FAX 817-468-3122www.hmscompounds.com
Send product releasesto Robin Norvell at
www.circuitsassembly.com Circuits Assembly DECEMBER 2004 47
T he ability of devices to withstand ESD events isagain becoming an issue. While design engineersduring the 1980s and ’90s made devices less sen-
sitive, the demand for performance and the scaling ofdevices is causing a reverse in the withstand voltagesthat cause catastrophic failure. Processes need to bereviewed with sensitivities in mind to ensure that ESDcontrols are adequate.
Unlinke when ESD process control standards werejust beginning to be written, today’s users can start withbasic standard and control issues. For example, the ESDAssociation standard for ESD process control, ANSI/ESD S20.20 – 1999, has the basic principles for ESDcontrol written in its foreword:
• All conductors in the environment, including per-sonnel, must be bonded or electrically connected andattached to a known ground or a contrived ground.
• Assessment of the ESD hazard created by electro-static charges on the necessary non-conductors in thework place is required to ensure that appropriateactions are implemented, commensurate with risk.
• Transportation of ESD-sensitive items outside anElectrostatic Protected Area requires enclosure in staticprotective materials, although the type of materialdepends on the situation and destination. Inside a Pro-tected Area, low charging and static dissipative materi-als may provide adequate protection. Outside a Protect-ed Area, low charging and static discharge shieldingmaterials are recommended.
The main points of the ANSI/ESD S20.20 programare to ground or connect all conductors including peo-ple, remove all unnecessary insulators, establish a planfor insulators that are required and physically packageESD-sensitive items when not in a protective area.
Accomplishing these tasks means considering cer-tain options: What type of grounding system is avail-able for use? Are the people highly mobile? What levelof process-required insulators are considered a threat,and how are they handled? What is the proper packag-ing? How does staff know what to do? How do I makesure all my control measures are still working?
In North America, some of these questions are read-ily answered. Grounding is usually accomplishedthrough the third wire or equipment ground. The con-nection of ESD control items and conductors to equip-ment ground is controlled by the standards in the
ESD Association
National Electric Code. If there is a need to establish asecondary or auxiliary ground path, ensure that the twogrounds are at the same potential and connected to pre-vent any ground loops or safety exposures.
Once grounding is established, the question ofgrounding people can be addressed. Two effective waysare the use of a wrist strap (which is required when at aseated operation) or a footwear/flooring system. Thelatter has the greatest flexibility, but may be expensive toimplement should the facility lack the proper floor.
As protected areas are identified, items that will beused in them must be identified. ANSI/ESD S20.20,Table 1, lists items that can be considered for inclusionin protected areas. Each should be reviewed to deter-mine if it is needed. For example, does the ProtectedArea need a work surface? Most do, but there could beexceptions. For example, if the process is simply to takea part from the ESD protective package and install itinto an assembly or subassembly, a work surface maynot be needed. If parts need to placed on a surface forinspection, assembly or temporary storage, then thework surface must be ESD-controlled.
If an ESD control item is selected, then there must bea method to verify it is working on a periodic basis.Each ESD control item needs to be verified; the test andfrequency of testing is defined by the user. The table inANSI/ESD S20.20 suggests which standards informa-tion can be used to establish a test method. An examplewould be to verify wrist straps on a daily basis with awrist strap test, or quarterly verifying a work surface’sresistance to ground.
An established training plan helps ensure therequirements for the process are known. Also, initialand recurrent training ensures proper protocol andprocedures. A way to verify understanding must bedefined, whether it is a test, observations or any otherdocumented method.
Bibliography
1. ANSI/ESD S20.20-1999 - Protection of Electrical and ElectronicParts, Assemblies, and Equipment (Excluding Electrically InitiatedExplosive Devices), ESD Association, Rome, NY.
2. ESD TR20.20-2000 - ESD Handbook, ESD Association, Rome, NY.
Getting GroundedHigher performance devices renew the need for proper ESD control.
This column is a
regular contribution
of the ESD Associa-
tion, Rome, NY;
(315) 339-6937;
email: [email protected].
ESDBasics
ProcessDoctor
What are the field failure mechanisms caused byresidues?
1. Electrochemical migration (Figure 1). Metallicdendrite short bridges a power to ground or lesser volt-age potential point. Cause: flux residues and moisturebridging the holes or traces.
2. Electrochemical migration due to high chlorideresidues on a component used on a no-clean assembly.
3. Electrochemical migration caused by high chlo-ride residues on a component used on a water-solubleflux and marginal cleaning of the assembly.
4. Electrochemical migration due to high bromideand chloride residue from bare-board HASL finishingand the wet monomer left in the void areas of a chip-bonder epoxy.
5. Electrochemical migration due to condensingmoisture on a no-clean assembly with high levels ofchloride and bromide HASL flux residues.
6. Copper sulfate corrosion (Figure 2). Exposed cop-per in a heavy cloud of sulfate residues, typically fromoutgassing in a non-vented enclosure and no coatingprotection.
7. Electrical leakage (Figure 3). Stray voltagethrough conductive residues in the presence of mois-ture or other fluid media and a conductive residue.No visible residue is seen but typically leakage can bemeasured.
8. Electrical leakage due to capacitor plating conta-mination. Cause: typically, high sulfate residues that aremoisture-absorbing and conductive.
9. Electrical leakage due to heavy no-clean fluxresidues not completely heated and complexed to createthe benign residue, but the residue becomes a moisture-absorbing conductive pathway.
10. Electrical leakage due to hand soldering with no-clean flux using extra no-clean flux from a bottle.
48 Circuits Assembly DECEMBER 2004 www.circuitsassembly.com
O EM and EMS firms are encounter-ing important issues involving cir-cuit- and system-level perfor-
mance as it relates to specific areacleanliness. Specific area cleanliness is theamount of contamination on the surface,below the component, in the board sub-surface and between the traces – visibleand invisible. These areas are difficult to examine indi-vidually using common industry methods, and conta-minants can be diluted and overlooked by examiningthe board only as a whole.
Are all these residues (contamination) detrimental?No, but some can be if not completely heated. No-cleanfluxes have been formulated to leave a benign insulativeresidue after soldering. Water-soluble fluxes aredesigned to be completely removed by aqueous clean-ing with no residue left behind. Over the past 15 years,we have learned many things about these two processes.A VOC-free, no-clean flux (water base) can cause den-drite growth in areas where it hasn’t seen enough heatto remove the entire amount of water carrier. This isdue to a strong acid structure with a pH of 2.4 typical-ly. Flux residues make up only part of the residues ateach solder joint. Remember, the fabricator and com-ponent vendor left residues from their processes atthese same solder joints. We must understand the dif-ferences between good protective residues and bad cor-rosive residues, and the critical parameters to test andmonitor that identify these issues.
Are residue-related problems becoming more com-mon? Many problems have been misdiagnosed, andnew designs have a much higher level of circuit sensi-tivity. Many EMS firms have seen large increases in notrouble found (NTF) returns. These returns encoun-tered an event in the field, but by the time the units wereretested at the bench of the EMS the problem disap-peared because the residues dried between time of fail-ure and shipment to be tested. For a good environmen-tal check, place the units in high humidity (35°C/65%RH) overnight, and then retest in the morning. Ifthe units fail, the failure is residue-related. (Watch forfollow-up columns on specific area cleanliness and howto address it.)
Terry Munson is
with Contamination
Studies Laboratory
(CSL, residues.com),
Kokomo, IN;
(765) 457-8095;
ResiduGuru@
aol.com.
Terry Munson
Understanding Specific AreaCleanlinessLeave no residues behind.
FIGURE 1: Electro-chemical migration.
FIGURE 2: Coppersulfate corrosion.
FIGURE 3: Electricalleakage.
