Surface Mounting SMT LED IndicatorComponentsApplication Note 1060
Contents• Surface Mount LED
Indicators• Standard EIA Tape and Reel
Packaging• Moisture Barrier Envelope
Packaging• SMT LED Device Lead
Material• PC Board Pad Design• Automatic Placement
Equipment Considerations• Solder Paste• Convective IR Reflow
Soldering• Type 2 PC Board Processing
with LED Components• Through-The-Wave Soldering
Surface Mount LED IndicatorsCircuit board assemblies usingsurface mount technology (SMT)are now common and SMT LEDindicators are being used onmany of these SMT boardassemblies. There are currentlythree basic types of AgilentTechnologies SMT LED indicatorcomponents:
1. HLMx-xxxx domed and flattop subminiature lamps withformed leads:• Option 011 “gull wing” leads.• Option 021 “yoke” leads.• Option 031 “Z-bend” leads.
2. HSMx-xxxx Chip LED and flipchip LED indicatorcomponents.• HSMx-C670, -C650, -H670,
-H690, -S670, -S690 topemitting components.
• HSMx-H630, -H730 reversemount components.
• HSMx-R661, -R761, -S660,-C660 right angle emittingcomponents.
3. HSMx-Axxx-xxxxx PLCC SMTLED
All these LED indicatorcomponent types may bemounted to a printed circuit(pc) board using automaticplacement equipment andattached using a reflow solderprocess.
This application note providesinformation on how tosuccessfully attach SMT LEDindicators onto a pc board.
Standard EIA Tape and ReelPackagingSMT LED lamps are packagedtape and reel in accordance withEIA Standard 481, Taping ofSurface Mount Components forAutomatic Placement. Reel andtape dimensions conform to EIAstandards with individual SMT
LED lamps in the embossedcarrier tape spaced on 4 mm(0.157 in.) centers. Figures 1athrough 1e show the typical EIAstandard dimensions for thereels and embossed tapes.
Moisture Barrier EnvelopePackagingThe optical grade materials usedin SMT LED components absorbmoisture directly out of the air.Absorbed moisture in SMT LEDcomponents that have beenreflow soldered to a pc board istypically of minor concern.However, moisture absorption inSMT LED components prior toreflow soldering is of seriousconcern. If moisture is absorbedby SMT LED components priorto soldering, the entrappedmoisture turns to superheatedsteam during the solder process.The pressure of this superheatedsteam fractures the packages ofthe components causingcatastrophic failure. Therefore,it is of vital importance toprotect SMT LED componentsfrom absorbing moisture prior tosoldering.
To protect the SMT LEDcomponents from moistureabsorption during shipping andhandling, reels for SMT LEDcomponents may be packaged inmoisture barrier envelopes, asillustrated in Figure 2.
2
Figure 1a. 12 mm Embossed Cavity Carrier Tape Detail for HLMP-6XXX/-PXXX Series Subminiature SMT LED Lamps.
2
CATHODE LEAD
D
P0
P2
F
E
W
D1PFEED DIRECTION
"GULL WING" LEAD OPTION 001 TAPE DETAIL
t
K0
CATHODE LEAD
"YOKE" LEAD OPTION 021 TAPE DETAIL
CATHODE LEAD
"Z-BEND" LEAD OPTION 031 TAPE DETAIL
NOCOMPONENTSCOMPONENTS
NOCOMPONENTS
END TAPE START
USER DIRECTION OF FEED
LEADER500 mm (19.7 IN.)
TRAILER160 mm (6.3 IN.)
LABELTHIS SIDEOF REEL
12 mmEMBOSSED CAVITYCARRIER TAPE
DIMENSIONS PER ANSI/EIASTANDARD RS-481.ALL DIMENSIONS ARE INMILLIMETERS (INCHES)
D 1.55 (0.061) DIA.
D1 1.00 (0.039) DIA.
E 1.75 (0.069)
F 5.50 (0.127)
KO 3.05 (0.120)
P 4.00 (0.157)
PO 4.00 (0.157)
P2 2.00 (0.079)
t 0.30 (0.012)
W 12.00 (0.472)
THICKNESS OF TOP COVERTAPE 0.10 (0.004) MAX.
Figure 1a. 12 mm Embossed Cavity Carrier Tape Detail for HLMP-6XXX/-PXXX Series Subminiature SMT LED Lamps.
3
Figure 1b. 8 mm Embossed Cavity Carrier Tape Detail for HSMX-C650, -C670, -H670, -S670, -C655 Chip LED Lamps
4
Figure 1c. 8 mm Embossed Cavity Carrier Tape Detail for HSMX-H630 and HSMX-H690, -S690 Chip LED Lamps.
5
Figure 1d. 8 mm Embossed Cavity Carrier Tape Detail for HSMX-C660, -S660 and -R661 Right Angle Chip LED Lamps
6
Figure 1e. 7 Inch and 13 Inch Reel Details.
A
N C
T
D2
OPERATOR ___________________AGILENT PART NO. _____________DATE CODE ___________________TAPING DATE _________________ELEC. VALUE _________________TOLERANCE __________________QUANTITY ____________________CUSTOMER PART NUMBER _____
OPERATOR ___________________AGILENT PART NO. _____________DATE CODE ___________________TAPING DATE _________________ELEC. VALUE _________________TOLERANCE __________________QUANTITY ____________________CUSTOMER PART NUMBER _____
13 INCH REEL DETAIL
A
N C
T
D2
OPERATOR ___________________AGILENT PART NO. _____________DATE CODE ___________________TAPING DATE _________________ELEC. VALUE _________________TOLERANCE __________________QUANTITY ____________________CUSTOMER PART NUMBER _____
7 INCH REEL DETAIL
DIMENSIONS PER ANSI/EIASTANDARD RS-481ALL DIMENSIONS ARE INMILLIMETERS (INCHES)
7 INCH REEL 13 INCH REEL
A 178.0 (7.0) 330.2 (13.0)
C 13.0 (0.512) 13.0 (0.512)
D2 20.2 (0.795) 20.2 (0.795)
N 60.0 (2.362) 100.0 (3.937)
8 mm 8 mm14.4 (0.567) 14.4 (0.567)
12 mm 12 mm18.4 (0.724) 18.4 (0.724)
T
7
Each envelope containsdesiccant. To assure themoisture barrier seal, it isimportant to protect theseenvelopes from being puncturedby sharp objects such as staples.Once opened, SMT LEDcomponents should be handledin accordance with therecommendations for theirappropriate moisture sensitivityclassification. The Joint IndustryStandard J-STD-020, Moisture/Reflow Sensitivity Classificationfor Plastic Integrated CircuitSurface Mount Devices, issuedby the EIA/JEDEC JC-14.1Committee establishes thenecessary handlingrecommendations for eachmoisture sensitivityclassification. For informationon the appropriate moisturesensitivity classification ofAgilent Technologies SMT LEDcomponents, contact yourAgilent Technologiesrepresentative.
SMT LED Device Lead MaterialThe lead base metal and surfacefinish for SMT LED componentsare listed in Table 1. Thesubminiature lamp componentsutilize a lead frame in theirconstruction. The various chipLED and flip chip LEDcomponents utilize a pc board asthe device substrate.
PC Board Pad DesignThe design of the pc boardmetallic attachment pads isimportant to assure bothposition on and attachment toan SMT board assembly. Soldercoated one ounce copper padsare best for reflow soldering.
PC Board Pad Design Considerationsand Device-to-Device Pad AlignmentPlacing an SMT LED componenton the pc board so its axis isoriented perpendicular to thelong dimension side of theboard, as shown in Figure 3, willtend to reduce stress on thedevice during temperaturecycling. Placing the axis of anSMT LED component parallel tothe long dimension side of the pcboard will increase theprobability of defects. Theproper design of pc boardattachment pads, as illustratedin Figure 4, will increase theprobability of proper reflowsolder connections. Pad sizeshould not exceed recommendedpad dimensions by more than0.25 mm (0.010 in.). Accurateplacement of the SMTcomponents onto the pc boardattachment pads enhances theprobability of proper alignmentafter solder freeze. When the pcboard pads are of the correctsize in relation to the deviceleads, the SMT LED componentswill self center align withrespect to the pads, assisted bythe capillary attraction/wettingforces of the hot liquid solder.
PC board traces should connectto the center of each attachmentpad. Traces that connect to theouter edges of pads impart atorque to the SMT LEDcomponent which contributes toskewing and off centeringproblems. Adjacent attachmentpads for SMT LED componentselectrically connected in seriesshould be connected with a tracethat is a maximum of 0.20 incheswide. Solder resist maskingshould be well defined aroundthe perimeter of the attachmentpads, without voids or smearsover the pads that will inhibitthe formation of good solderconnections.
Subminiature Lamp ComponentsFigure 5 shows the mountingorientation to a pc board for theOption 011 “gull wing,” Option021 “yoke,” and Option 031 “Z-bend” lead subminiature lampcomponents. All three optiondevices are for mounting on thecomponent side (non-solderside) of a pc board, with boththe “yoke” and “Zbend”components mounted upsidedown through a hole in the pcboard. Installed on a 1.52 mm(0.060 in.) thick pc board, thelamp dome of a “yoke” leadcomponent will protrude out thesolder side about 0.38 mm(0.015 in.), and a “Z- bend”component will be flush torecessed 0.38 mm (0.015 in.).
Table 1. Lead Base Metal and Lead Finish for SMT LED Indicator Components.
SMT LED Indicator Component Lead Base Metal Lead Finish
HLMP-6XXX/-PXXX Copper/Iron Alloy, OLIN 194 Solder Plate, 85% Sn/15% Pb
Chip LED and Flip Chip LED Copper on pc Board Substrate Gold over Nickel Alloy
8
Figure 6 shows the pc board padlayout for the Option 011 “gullwing” lead components. Figure 7shows the pc board pad layoutsfor Option 021 “yoke” lead andOption 031 “Z-bend” leadcomponents.
A Type 2 pc board assemblycontains both surface mount andthrough hole components. ForOption 021 “yoke” lead andOption 031 “Z-bend” leadcomponents mounted on a Type2 board that will be wavesoldered, the clearance throughhole in the pc board should betemporarily closed off on thesolder side with a removablesolder resist cover, as shown inFigure 8. This removable solderresist cover prevents flux andsolder from flowing up throughthe clearance hole during wavesolder and being deposited onthe leads the LED device. Thisunwanted excess solder depositrestrains the component leadsfrom absorbing thermal stressesduring temperature cycling andwill inevitably lead tocatastrophic failure of the SMTLED component.
Figure 2. Moisture Barrier Envelope Packaging for SMT LED Indicator Components.
Figure 3. Recommended Orientation of SMT LED Components on PC Boards forMinimum Stress.
REEL OF SMTLED DEVICES
DESICCANTINSIDE
MOISTURE BARRIERENVELOPE
SEALEDENVELOPE
IDENTIFICATION LABEL
PC BOARDLONG DIMENSION
AXIS OF SMT LED DEVICE
SOLDER CONNECTIONS
CL CL
9
Figure 4. PC Attachment Pad Design Considerations for SMT LED Components. Pad Dimensions should not exceed 0.25 mm (0.010) in.)Recommended Size.Figure 4. PC Attachment Pad Design Considerations for SMT LED Components.Pad Dimensions should not exceed 0.25 mm (0.010) in.) Recommended Size.
9
�����
������
����
������
CORRECTPAD SIZE
PADSTOO LONG
PADS TOO WIDEPC BOARD ATTACHMENT PAD SHAPES
SMT LED ISSELF CENTERED
REFLOW SOLDERED SMT LED
TOMBSTONINGSMT LED SKEWED SMT LED
0.020 IN. MAX.
GOOD DESIGN INFERIOR DESIGN
PADS IN A SERIES CONNECTION
GOOD SOLDERMASKING
UNACCEPTABLESOLDER MASKING
SOLDER MASKING
SOLDER MIGRATION
SOLDERMIGRATIONADDS A TORQUE
POOR TRACECONNECTION
GOOD TRACECONNECTION
CIRCUIT TRACE-TO-PAD CONNECTIONS
10
Figure 5. Orientation of HLMP-6XXX/-PXXX SMT LED Component Options on a PC Board.
Figure 6. PC Board Attachment Pad Layout for HLMP-6XXX/-PXXX “Gull Wing” Lead Option 011 Single Indicator and Option 013 Linear ArraySubminiature SMT LED Components. PC Board Solder Dipped, Hot Air Leveled.
CLEARANCE0.13 mm (0.005 IN.) MAX.
APPROXIMATE PROTRUSION1.52 mm (0.060 IN.)
APPROXIMATELYFLUSH
OPTION 011"GULL WING" LEAD
OPTION 021"YOKE" LEAD
OPTION 031"Z-BEND" LEAD
0.89(0.035)
3.56(0.140)
0.45(0.018)
0.89(0.035)
0.45 (0.018)
1.78(0.070)
PAD SPACING ON 2.54 (.100) CENTERS
TOLERANCE ISNON-CUMULATIVE
"GULL WING" LEADOPTION 011
DIMENSIONS ARE INMILLIMETERS (INCHES)
11
Figure 7. PC Board Attachment Pad Layout for HLMP-6XXX/-PXXX “Yoke” Lead Option 021 and “Z-Bend” Lead Subminiature SMT LEDComponents, Mounted Dome Down Through Clearance Hole in PC Board. PC Board Solder Dipped, Hot Air Leveled.
Figure 8. Removable Solder Resist Cover to Close Off Through Hole in a Type 2 PC Board to Protect LED Component During a Wave SolderOperation.
6.60 (0.260)
3.30 (0.130)
0.64(0.025)
1.27(0.050) 0.45
(0.018)
0.89(0.035)
#27 DRILL3.73 (0.147) DIA.CLEARANCE HOLETHROUGH PC BOARD
DIMENSIONS ARE INMILLIMETERS (INCHES)
"YOKE" LEAD OPTION 021
0.89(0.035)
0.45(0.018)
1.27(0.050)
3.30 (0.130)
6.60 (0.260)
#27 DRILL3.73 (0.147) DIA.CLEARANCE HOLETHROUGH PC BOARD
SMT LED DEVICE MOUNTED DOMEDOWN THROUGH CLEARANCE
HOLE IN PC BOARD
"Z BEND" LEAD OPTION 031
REMOVABLE SOLDERRESIST COVER
OPTION 021"YOKE" LEAD
OPTION 031"Z-BEND" LEAD
0.60 IN.
HLMP-6XXX/-PXXX
12
Chip LED Lamp ComponentsFigure 9 shows the pc boardattachment pad layouts for theChip LED and flip Chip LEDcomponents. These attachmentpad layouts may be used forboth reflow solder andconductive attachment. Thewidth of the attachment pads isabout 0.1 mm (0.004 in.) narrowwith respect to the width of therespective top emitting andreverse mount components toassure alignment of the devicewith respect to the pads. Note,the reflow solder pads are on apc board that has been solderdipped and hot air leveled; theepoxy attachment pads are cleanbare copper.
Automatic Placement EquipmentConsiderationsThe subminiature Option 011“gull wing” lead components aremounted upright in theembossed cavities of the carriertape. A hole is located in thebottom of each embossed cavityto allow an automatic pick andplace machine to utilize a pushpin to assist in device removalfrom the carrier tape.
The subminiature Option 021“yoke” lead and Option 031“Zbend” lead components aremounted top side down in thecarrier tape. Since the rounddomes of the device packagesare pointing down, the bottomsof the embossed cavities do nothave push-pin holes. Also, thecarrier tape for the chip LEDcomponents does not have push-pin holes in the bottom of theembossed cavities. Thus, thepush-pin action of the automaticpick and place machine must bedisabled when picking thesedevices from the carrier tape.
The top side surfaces of SMTLED components, as they sit inthe embossed cavities of thecarrier tape, present to a pick-up tool either a surface that isnot perfectly flat or a rounddome. As a result, the typicalstainless steel vacuum pick-uptool may not form a vacuum sealwith the device package andthus may not be able to pick itout of the embossed cavity.Figure 10 shows a flat soft tippick-up tool for picking up chipLED components andsubminiature lamp Option 021“yoke” lead and Option 031 “Z-bend” lead components that aremounted upside down in theembossed cavities. The soft tippick-up tool is usually made ofnylon or other soft plastic. Forpicking up subminiature lampOption 011 “gull wing” domedcomponents, the end of the softtip should be contoured concaveto fit snugly over the dome ofthat particular SMT LED deviceto form a vacuum seal.
13
Figure 9. PC Board Attachment Pad Layouts for Chip LED and Flip Chip LED Components.
1.25(0.049)
1.25(0.049)
1.10(0.043)
1.10(0.043)
1.50(0.059)
1.75(0.069)
1.75(0.069)
2.00(0.079)
1.1
1.40 mm
1.25 mm
1.15 mm
2.00(0.079)
2.40(0.094)
1.75(0.069)
1.00(0.039)
1.00(0.039)
1.75(0.069)
HSMX-C670, -H670 SERIESHSMX-S670 SERIES
HSMX-C650HSMF-C655
1.0 1.0
0.8
1.4
HSMX-R661/R761 SERIES
0.8 0.8
0.8(0.031)
0.85
HSMX-H690/H790 SERIES
3.4
1.3
0.8
HSMX-S690 SERIES
2.4
0.8
2.00 DIA. PCB HOLE
0.9
0.9
0.2
2.05.0
1.5
RWS CENTER
14
Figure 10. Soft Tip Vacuum Pick-up Tool for Extracting SMT LED Components from Embossed Carrier Tape.
Solder PasteFor best results, an SN63eutectic solder paste, liquidus at+183 °C (+361 °F), should beused. SN62 solder pastecontaining 2% silver, liquidus at+189 °C (+372 °F), may be usedwith the chip LED devices, withthe advantage of obtainingstronger solder connections, buthigher cost. The solder pasteshould contain 85 to 95% byweight (38 to 67% by volume)solder ball powder, with the sizeof the spherical solder ballsscreened -200/+325 mesh. Thesolder paste should be stableover time after deposition on thepc board. After deposition, awell formulated paste will notdegrade or change reflowcharacteristics due to moistureabsorption and oxidation overtime period of 12 hours at roomtemperature. Refrigeratedstorage of unused solder pasteextends shelf life, typicallybeyond three months at 0 °C(+32 °F). The solder paste maybe deposited onto pc board padsby either screen printing, using astencil, or by syringe dispensing.
The viscosity range of the solderpaste should be specified for thespecific deposition process to beused: between 500,000 and600,000 centipoise for screenprinting, between 700,000 and800,000 centipoise for stencilprinting, and between 350,000and 450,000 centipoise fordispensing. An 80 mesh screenwill provide a solder depositionthickness of 0.20 mm (0.008 in.).The solder paste should coverthe pad with a smooth, evencontour, without voids. Voids inthe deposited solder paste maybe due to contamination oroxidation on the pc board metalpads, improper solder pasteviscosity, clogged openings inthe screen mesh, or a “dirty”syringe dispensing tool. Sincesolder paste will wick outwardby 0.004 to 0.005 inches, thedeposited paste should cover theattachment pad just short bythis amount.
Convective IR Reflow SolderingAll SMT LED components maybe reflow soldered using aconvective IR process. Aconvective IR process usesmiddle to long infraredwavelengths (approximately4000 to 6200 nanometers).Approximately 65% of the energyis used to heat the air in thereflow chamber (convectiveheating) and 35% of the energydirectly heats the pc board andcomponents (radiative heating).Some systems are forced hot airsystems with a dual chamberdesign, where one chamber hasIR heaters to heat the air whichis then blown over the pc boardassemblies located in a secondchamber. In these systems,heating is 100% convective. Thepc board and components areuniformly heated to achievereliable solder connections. Thethermal stresses experienced bySMT LED components areminimized in a convectivethermal environment.
15
Figure 11 is a straight-linerepresentation of a nominaltemperature profile for aconvective IR reflow solderprocess. The temperature profileis divided into four processzones with four DT/Dtimetemperature change rates. TheDT/Dtime temperature changerates are detailed in Table 2. Thetemperatures are measured atthe component to pc boardconnections.
Process Zone P1In process zone P1, the pc boardand SMT LED components areheated to a temperature of +125°C to activate the flux in thesolder paste. The temperatureramp up rate, R1, is limited to +3°C per second to allow for evenheating of both the pc board andthe SMT LED components.
Process Zone P2Process zone P2 should be ofsufficient time duration to drythe solder paste. Thetemperature is raised to a leveljust below the liquidus point ofthe solder, usually +170 °C (+338°F) for leaded IR reflow solderprocess and [+217 °C (+422.6°F)] for lead free reflow solderprocess.
Process Zone P3Process zone P3 is the solderreflow zone. In zone P3, thetemperature is quickly raisedabove the liquidus point ofsolder to +230 °C (+446 °F)[+260 °C (+500 °F)] for optimumresults. The dwell time above theliquidus point of solder shouldbe between 15 and 90 seconds. Itusually takes about 15 [60]seconds to assure propercoalescing of the solder balls
into liquid solder and theformation of good solderconnections. Beyond a dwelltime of 90 [150] seconds, theintermetallic growth within thesolder connections becomesexcessive, resulting in theformation of weak andunreliable connections. Thetemperature is then rapidlyreduced to a point below thesolidus temperature of thesolder, usually +170 °C (+338°F) for leaded IR reflow solderprocess and [+217 °C (+422.6°F)] for lead free IR solderprocess, to allow the solderwithin the connections to freezesolid.
Figure 11. The Temperature Profile for a Nominal Convective IR Reflow Solder Process. See Table 2 for Temperature (RX) Values.
Table 2. Convective IR Reflow Process Zones. See Figure 11.
enoZssecorP lobmyS DDDDDT DDDDD /T DDDDD emit
pUtaeH 1R,1P C°521+otC°52+ XAMs/C°3+
yrDetsaPredloS 2R,2P C°071+otC°521+ XAMs/C°5.0+
wolfeRredloS 3R,3P4R
)XAMC°532+(C°032+otC°071+C°071+otC°032+
PYTs/C°5.4+PYTs/C°5.4-
nwoDlooC 5R,4P C°52+otC°071+ XAMs/C°3-
230
200
150
100
50
25
125
170
183
0 15 30 45 60 75 90 105 120 135 150 165 180 195 210
T-TE
MPE
RA
TUR
E (
˚ C)
P1HEAT UP
P2SOLDER PASTE DRY
P3SOLDERREFLOW
P4COOL DOWN
R1
R2
R3 R4
R5
90s MAX.ABOVE183 ˚ C
t-TIME (SECONDS)
Note:Values shown in [] are for lead free IR reflow solder process.
16
[P1] Heat Up
[P2] Solder Paste Dry
[ P3] Solder Reflow
[P4] Cool Down
0255075
100125150175200225250275
0 20 40 60 80 100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
400
420
t-Time (Seconds)
T-Te
mper
atur
e (°C
)
60 - 150 sec
10 - 20 sec
255 +5/-0°C
217°C
[R1]
[R2]
[R3] [R4]
[R5]
Process Zone P4Process zone P4 is the cool downafter solder freeze. The cooldown rate, R5, from the liquiduspoint the solder to +25 °C (+77°F) should not exceed -3 °C(+26.6 °F) [-6 °C (+21.2 °F)] persecond maximum. Thislimitation is necessary to allowthe pc board and SMT LEDdevices to change dimensionsevenly, putting minimal stresseson the SMT LED devicepackages.
Figure 12: Recommended Sample Lead-Free Temperature Profile IR Reflow Solder Process. See Table 3 for “ Temperature [RX] Values.
Table 3. Recommended Lead-Free IR Reflow Process Zones. See Figure 12.
sessecorP lobmyS DDDDDT DDDDD /T DDDDD emit
putaeH ]1R[,]1P[ C°521+otC°52+ A/N
yrDetsaPredloS ]2R[,]2P[ C°712+otC°521+ A/N
wolfeRredloS ]4R[,]3R[,]3P[ C°552+otC°712+C°712+otC°552+
XAMs/C°3+XAMs/C°3-
nwoDlooC ]5R[,]4P[ C°52+otC°712+ XAMces/C°6-
Note:Values shown in [] are for lead free IR reflow solder process.
17
Type 2 PC Board Processing WithLED ComponentsA Type 2 pc board assembly hasboth SMT LED and through holeLED components installed. Theprocessing sequence of Type 2pc boards is important to assurefinal assembly yield. Thefollowing suggested processingsequences assure high post-solder yields for both the SMTLED and through hole LEDcomponents. The processesdescribed are assumed to behigh volume, automatedprocesses with auto-insertion ofthrough hole LED components.The SMT LED components areplaced onto the top surface ofthe pc board with automatedplacement equipment.Attachment epoxy may be usedto hold the SMT LEDcomponents to the pc boarduntil the board is reflowsoldered. The automated solderpaste screen printer, SMTplacement equipment, auto-insertion machine, reflow andwave solder machines, and postsolder cleaning unit are all partof a continuous in-line processwith automated board handlingequipment.
Preferred ProcessReflow solder SMT LEDcomponents prior to auto-insertion of through hole LEDcomponents. The reflow andwave solder operations areseparated by the auto-insertionoperation.
1. Screen print the solder pasteand deposit the attachmentepoxy for the SMT LEDcomponents.
2. Auto-place the SMT LEDcomponents.
3. Cure the attachment epoxyand dry the solder paste.
4. Reflow solder the SMT LEDcomponents.
5. Auto-insert the through holeLED components.
6. Wave solder the through holeLED components.
7. Clean the pc board assembly.
This process sequence has thefollowing advantages:
1. The SMT LED components areattached to the pc board priorto auto-inserting the throughhole LED components.
2. Since the SMT LEDcomponents are reflowsoldered, they are notdisplaced from the pc boardduring auto-insertion of thethrough hole LEDcomponents.
3. Wave soldering the pc boardafter solder reflow does notremelt the SMT solderconnections.
4. The through hole LEDcomponents are not exposedto the high temperatures ofthe reflow solder operation.
Alternate ProcessAuto-insert the through holeLED components prior toplacing the SMT LEDcomponents, then reflow andwave solder in direct sequence.
1. Screen print the solder pasteand deposit the attachmentepoxy for the SMT LEDcomponents.
2. Auto-insert the through holeLED components.
3. Auto-place the SMT LEDcomponents.
4. Cure the attachment epoxyand dry the solder paste.
5. Reflow solder the SMT LEDcomponents.
6. Wave solder the through holeLED components.
7. Clean the pc board assembly.
This process sequence has thefollowing advantages:
1. The through hole LEDcomponents are auto-insertedprior to attaching the SMTLED components.
2. The SMT LED components arenot subject to displacementoff the pc board during auto-insertion of the through holeLED components.
3. Since the through hole LEDcomponents are loose on thepc board (not soldered) theyare better able to withstandexposure to the hightemperatures of the reflowsolder operation.
4. Wave soldering the pc boardafter solder reflow does notremelt the SMT solderconnections.
Precautions When Handling HSMx-C540 and HSMx-C2201. Once the moisture barrier bag
unsealed, the best method isto finish the reel. Otherwise, itis advisable to immediatelystore the unfinished parts inthe moisture barrier bag andseal
2. For double-sided PCB withSMT components on bothsides, it advisable to subjectboth sides to one time reflowonly, meaning that thecomponents will be solderedduring the second reflow.
3. Avoid rinsing before solderreflow. If this is unavoidable,then bake dry thecomponents/ board beforesolder reflow.
18
Through-The-Wave (TTW) SolderingNot all SMT LED componentscan be mounted on the solderside of a pc board. See Table 3for a list of Agilent TechnologiesSMT LED components which canbe processed by TTW soldering.Attaching SMT LED componentsto the solder side of a pc boardusing TTW processing can beaccomplished by carefullycontrolling the wave solderprocess. It is absolutelyimperative that the SMT LEDcomponents be free of absorbedmoisture before being exposedto TTW solder processing, seesection titled Moisture BarrierEnvelope Packaging forappropriate handling measures.If the SMT LED componentscontain absorbed moisture,there is a high probability thatthe absorbed moisture will beturned into superheated steamby the large thermal mass of asolder wave, causing devicepopcorning to occur.
A nitrogen atmosphere solderwave machine is recommendedto achieve the highest possiblesolder connection yields. Theuse of a high quality no-cleanflux and SN63 eutectic solderare encouraged. Spraying the no-clean flux onto the solder side ofthe pc board is recommended.Coverage is superior to foamfluxing, and the amount of fluxdeposited onto the pc board canbe controlled to assure properfluxing of all SMT componentconnections.
It is critical that the temperaturedifference between the preheattemperature and the solderwave temperature must notexceed the maximum of +100 °C(+180 °F), as measured at asolder connection on the solderside of the pc board. SMT LEDcomponents, like many SMTceramic chip capacitors, are notable to withstand aninstantaneous thermal shock
temperature difference greaterthan +100 °C. The followingtemperature, dwell timeAbsolute Maximum Ratings forTTW processing must beobserved to assure high yields.
The following TTW dual wavesolder process is recommended:
1. Establish the correct preheattemperature, measured at asolder connection on thesolder side of the pc board,required to properly activatethe no-clean flux, for example+135 °C (+275 °F). Thispreheat temperature shouldbe reached only during thelast 20% of the travel throughthe preheat chamber to assureproper flux activation.
2. Set the solder wavetemperature to be less than+100 °C (+180 °F) above thepreheat temperatureestablished in Step 1, forexample, +135 °C (+275 °F)+100 °C (+180 °F) = +235 °C(+455 °F) maximum solderwave temperature.
Table 4. TTW Processing Compatibility of SMT LED Components
Absolute Maximum Ratings for TTW Processing of SMT LED Components
3. Set the machine conveyorspeed to limit the combineddwell time of an SMT LEDcomponent in the two solderwaves to no more that 10seconds.
4. Spray flux at roomtemperature.
5. Wave solder the pc board.6. Allow the soldered pc board
to cool to room temperaturebefore handling.
7. Post solder cleaning isnormally not necessary withthe use of a no-clean flux.
8. Should post solder cleaningbe included in the process,allow the soldered pc board tocool to either roomtemperature, for handcleaning, or to the processingtemperature of the in-linecleaning process.
9. For post solder cleaning, anin-line water cleaning processis recommended with watertemperature and hot air drytemperature set between +60°C (+140 °F) and +71 °C(+160 °F).
Product Series Approved for TTW (Yes/No)
HLMx-xxxx Subminiature Lamps No
HSMx-Cxxx Chip LEDs No
HSMx-Sxxx Chip LEDs No
HSMx-H670 Flip Chip LEDs Yes
HSMx-H690 Flip Chip LEDs Yes
HSMx-R661 Right Angle Chip LEDs and FlipChip LEDs
Yes
HSMx-Axxx-xxxxx PLCC SMT LED Yes
Temperature Difference Between Preheat andSolder Wave:
+100 °C (+180 °F)
Preheat: +160 °C
Solder Wave: +250 °C
Dwell Time: 10 seconds
www.agilent.com/semiconductorsFor product information and a complete list ofdistributors, please go to our web site.
For technical assistance call:Americas/Canada: +1 (800) 235-0312 or(916) 788-6763
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Singapore, Malaysia, Vietnam, Thailand, Philippines,Indonesia: (+65) 6755 2044
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Data subject to change.Copyright © 2003 Agilent Technologies, Inc.Obsoletes: 5988-7835EN
July 24, 2003
5988-9462EN
