dfx design for_cost

DfXEngineeringA Design for Cost approach to PCB Layout

www.dfxengineering.com

DesignForCostProcess

MaterialSelec+onandpartsize–DrivenbyMaterialType(costvs.performancetradeoffs),Sizerelatedtomastersheetsnotworkingpanelsandpre-pregselecIonopImizaIon(howdoesglassstyleaffectBOMcost,andStack-up/Construc+onType:ThisiswhereyouarefocusingwithyourquesIonsonbothhowarewerouIngoutofdevicesandhowmanydevicesarewetryingtoroutinasingleboard,canwedoitlessexpensivelybymakingseparatesmallerboards,whatinterconnectschemeisthebestcost.CpkOp+miza+onOnCapability:HerewereviewhowdotherouIngoftracechoicesdrivethefeaturesizerelaIvetothemarket’scapabilityat2.0Cpk,andisthereanalternatewaytomeetthattodrivefeaturesizetothecenterofthecapability.WhatistheguideforHDIvs.ConvenIonal.Ifwechoseabelow1.0CpkDesignfeatureisourdetecIonsystemadequateforthevolumeweareproducing.

ThedesignforcostprocesshasthreemajorareastofocusonforopImizingthecostfeaturesinadesign.Thesethreeareasshouldinteractrepeatedlytorefinetothebestcostvs.performancetradeoff

DfXEngineering,LLC,2016

DesignGoal•  WhatisyourproducIonvolumeandhowdoesitcompareto

capacity?AreyouintherightproducIonsiteforyoursize.•  WhatEnvironmentalCondiIonswillyouoperatein?•  Whatreliabilityleveldoyourequire?•  Whatisyourcostpriorityranking?•  WhatareyourtesIngrequirements?•  IsdeliveryImeandproximityasignificantfactor?

•  UseFMEAtoinformthedecisionprocess.


RobustMarket

KnowyoursupplierscapabiliIes,andmaterialvendors


MATERIALSELECTIONPerformance,Dkandsize

BOMCostAnalysisBasis

AsMaterialisthemostsignificantfactorinPCBwewilltalkaboutbuildingacostmodelfromthebasematerial,up.EarlyImespentintheareasofmaterialtype,andmaterialuIlizaIonwillpaythebiggestreturns.

Pre-preg FR4

Cost index %

1078/1086 1.2

1080 1,0

1067 1.75

106 2.35

2116 1.20

1501/1506 1.65

3313/2113 1.55

7628 1.25


*Pricesshownareexamplesonlyandneedtobeupdatedtospecificcircumstances

1Ghz–DfResinRich,ResinPoor

0.000

0.005

0.010

0.015

0.020

0.025Std.Loss

UpperMidLoss LowLoss VeryLowLoss

MaterialSelecIonisMoreComplex



0.000

0.005

0.010

0.015

0.020

0.025Std.Loss


MaterialSelecIonisMoreComplexVendorBaseandMaterialchoiceshavegrowndramaIcally.Knowyourneeds.



0.000

0.005

0.010

0.015

0.020

0.025

0.030Std.Loss


MaterialSelecIonisMoreComplexAsMicrowaveJournalsays:FrequencyMaCers!


MaterialSelecIonDecisionTree

TgDecisionPoint

KeyFactorConsidera+ons:•  OverallThickness•  AspectRaIo•  AssemblycondiIons

includingrework•  ReliabilityUsefulLife

Target

DkRange DfRange

KeyFactorConsidera+ons:•  ImpedanceGoals•  LayerConstraints•  ResinContent(fill)•  GlassStyles

KeyFactorConsidera+ons:•  OperaIngFrequency•  LossSensiIvity•  CopperRoughness

Profile

PicktheBestFitineachofthesetofindtheidealmeaterialcost


MaterialSelecIonCostImpactCostFactor

1X

2X

3X

150Tg

170Tg

>200Tg

3.7Dk

3.5Dk

<3.0Dk

STD

RTF

VLPorHVLP

CriIcalareasarereliability,yieldloss,andavailabilityAddiIonalConsideraIonofHalogenFreeorNot

0.011Df

0.009Df

<0.005Dk

0.006Df


MaterialCostvPerformanceAnalysis

UIlizeanextensivematerialtesIngprogramtoprovideacomprehensivecostv.performanceanalysisspecifictoyourapplicaIon.

Mainvariablestoconsider,Tg,Dk,Df

0

1

2

3

4

5

6

LaminateCost

FinalPCBCost16L

FinalPCBCost20L


MATERIALOPTIMIZATIONBestFitPanel

MaterialOpImizaIon

DFMandDFCanalysiswillopImizepartsize,arrayandworkingpaneltoprovidethelowestcost,mostefficientsoluIon.DependingonmaterialselecIonmasterpanel’sofferedcanvary,opImizingtothematerialprovidesthelowestuIlizedsquareinchesperpart.


PanelU+liza+on

PCBLaminatematerialispurchasedinMastersheetsandthencutintoworkingpanels.TheMastersheetscomeinsizesthatareeasyforthelaminatesupplierstomanufacture.TheworkingpanelsareselectedtofitontheequipmentinthePCBfactory.LaminatesaresoldinPricepersquarefoot,sothebiggerthepanelthemoreexpensive

TypicalMasterSheetSizes:36x4840x4842x48

*SpecialOrdersizesareavailableinsomecases

StandardMasterPanelSizes

PanelizaIon


PanelU+liza+on

TypicalWorkingPanelSizes:18x2420x2421x24

36”

24”

18”

48”

*Therearemanyop+onsdependingontechandtooling

StandardPanelSizes

WorkingPanelsarethencutoutofthemastersheet,evenlyifpossibletomaximizetheuIlizaIonofthematerial.Themorepartsonaworkingpanelthelowertheunitcost.Bothworkingandmasterpaneldofactorintomaterialcost.WecanexpressworkingandmasterpaneluIlizaIons

WorkingPanelDevelopment


PanelU+liza+on-crosscuRng

CrosscunngisaworkingpanelopIoninsomecases.ItreliesoncunngmaterialindifferentdirecIonswhichcanimpactscalefactors.DensityandconstrucIonconsideraIonsneedtobeevaluated,andifavailablecanbeagoodwaytoreducetheeffecIvesquareinchesperpart.

WorkingPanelAlternaIves


PPSI–PricePerSquareInch

.

Sincethisistheunitofshipment;whenweusethecomparaIvetermpricepersquareinchweneedtocompareunitpricetoareashipped.ForumlaPPSI=UnitPrice/(ArrayArea/Arraynumberup)UnitpriceisdivideUnitPricebytheareaofthearraydividebythearraynumberup.ThiswaywecapturetheUnitPartplusit’sporIonoftherails.Effec+vesquareinchesperpartisthebestcompara+veindexwhenanalyzingPCBop+ons.

Shownhereisa6-uparrayor6singlePCBImagesthatareconnectedbytabs,andtwoassemblyrailsareapached.OqenthePCB’saresoldasanarray.(Anox-outarrayassumesallimagesonthearrayareGood)

PanelizaIon–ArrayDesign


PanelU+liza+on Inthisexampletheredboxesshow6PCB’sorPCBarrayspanelizedonan18x24.WewoulddividetheREDareabytheBLUEareatocalculatePaneluIlizaIonasapercentage.SincePCBlaborcostsareappliedtoworkingpanelsthemorepartsonapanelthelowertheunitcost.Numberupperworkingpanelisthenumberoftotal1upimagesontheworkingpanel(Arraynumberupxarray’sperWPNL)Wecanneverreach100%uIlizaIonbecauseweneed

spacebetweenpartsforcunngtoolstoseparatethem,weneedapanelbordertoapachtosomeelectroplaIngequipment,andweneedsomeroomfordestrucIvetesIngcoupons.ComparaIveanalysisshouldbeusedtoassessthequalityofyourpricinganddesigns.

24”

18”

PanelizaIon


FUNCTIONANALYSISHowmanyfuncIonsareIedinoneboard

HowmanyFuncIons

Mainlogicboard

Processor

4G Wi-FiBT

PCBbudgetcombined

Processor

4G

Wi-FiBT

PCBbudgetseparate

CansizesandrouIngbeopImizedtobreakoutPCB’sintomoremanufacturablelowercostunitwithdifferentinterconnectscheme

camera camera

compare


SameDeviceDesigns,DifferentCostConstrucIons

PCBbudgetcombined

Processor

4G

Wi-FiBT

PCBbudgetseparate

Mainlogicboard

Processor

4G Wi-FiBT

camera

cameracompare

TotalLayers=10HDI(2+6+2)NumberUp18x24=16(4”X5”)BOMCost=$20MaterialPartCost=$1.25

TotalLayers=10HDI(2+6+2)NumberUp18x24=44(2”x4”)

BOMCost=$20MaterialPartCost=$.23

MainBoard

TotalLayers=6HDI(2+2+2)NumberUp18x24=154BOMCost=$12MaterialPartCost=$.07

TotalLayers=4HDI(1+2+1)NumberUp18x24=300BOMCost=$10MaterialPartCost=$.02

4GCard AccCard(2X)

PCBBudgetSignificantlyReducedDfXEngineering,LLC,2016

PanelizaIonDifferences


PROCESSPARAMETERSELECTIONOpImizefeaturesforthecenternotthelimit

ReferencePlaneSelecIon

S

P

S

P

S

Split

RP

P

SelecIngtherightreferenceplanearrangementcanopImizefeaturesize.ConsiderreferenceplanestwolayersawayorlowerDkMaterialselecIontoimprovefeaturesize.Otherimportantstack-upconsideraIonsforbestmanufacturingcostare:•  Balancedcoppercores•  Goodref.distanceforL/W

OpIzaIon•  ReducevariaIoninpre-preg

selecIontoavoidlayuperroryeildimpact.


BOMCostAnalysis

DFM/DFCanalysiswillbreakdowneverylayerinthestack-upforcomparaIvecostanalysis.GlassStyle,coreconstrucIonandresincontentwillhavecostimpactontheBOMcost.CostfactorsdynamicallyadjustbasedonuseoverImeandnewmarketentrantslike1037,1027glasswillchangepricebasedonusage,soneedtomaintainconInualupdatesforImelycosInginyourmodel.

Pre-preg FR4

Cost index %

1078/1086 1.2

1080 1,0

1067 1.75

106 2.35

2116 1.20

1501/1506 1.65

3313/2113 1.55

7628 1.25


*Pricesshownareexamplesonlyandneedtobeupdatedtospecificcircumstances

HDIvs.ConvenIonal

Inner Lam Drill PlateOuterEtchSES

SM/Finish Test

ConvenIonal

HDI

Inner Lam Drill PlateOuterEtchSES

Plate/Cufill SM/Finish TestLam LaserDrill

OuterEtchSES

Repeatfornumberofbuilduplayers

Inlowerlayercountboards,materialcanbe30-45%ofcostleavingthemajorityofpriceforprocessingcostandOH.HDIaddssignificantcriIcalsteps.AnalysisonBOMcostsavingsandfeaturesizeshouldbereviewedwhenselecIngHDI,targettosaveatleast2coresreducIonintotallayersorifdevicepitchabsolutelyrequiresitforrouIng.


DeviceSelecIon

0.4mmPitch,0.0157”0.5mmPitch,0.0196”0.6mmPitch,0.0236”

MicroVia–HoleSize.004,Pad.010”,Copperfilledtogetfull.010padareaforsolderassembly.

.0057”rouIngSpace=1TrackrouIng48umat(0.0019”)traceandspace.0096”rouIngSpace=1TrackrouIngat75um.013”rouIngSpace=2TrackrouIngat65um

BestAspectRaIoonMVis1:1somaxdielectriconouterlayeris.004”.IfConvenIonaldrillingsmallestdrillis.008”andwillneed.018”padsize


RouIngGuidelines

Source:HDIHandbook


DecisionTreeForDesignChoices

FeatureSize 1.0Cpk 1.3Cpk 2.0Cpk

Linewidth(HDILayer)

45um 53um 63um

LineSpace 55um 65um 70um

AspectRaIo 0.9:1 0.8:1

Min.MechDrillSize

0.15mm(.006”)

0.20mm(.008”)

0.25mm(.010”)

MinCapturePadHDI

150um 180um 220um

MinCapturePadSTD

D+8 D+8 D+10

1:1

Understandthecri+calchangeoverpointsatyourfabrica+onsite


CpkFeatureAnalysis

AllcriIcalfeaturesshouldbestaIsIcallyanalyzedandreviewedtoensureyieldperformanceismaximizedreducingoverallprocesscostandprovidinglongtermcostreducIonopportuniIes.


SurfaceFinishConsideraIons

SurfaceFinish Cost Considera+ons Benefits

OSP 1 ShelfLifeLimits Flatness,easeofuse

ENIG 1.1 ProcessControls ConducIvity,flatness

ImmersionSilver 1.05 Environmental Cost,Flatness

ImmersionTin 1.2 Capacity Flatness

LFHASL 1.4 Capacity,Uniformity

Robust

ElectroplatedGold

2.0 BussScheme,Minimizearea

Bondability,Compressioncontacts

MajorConsideraIons:Assemblysitefamiliarity.Avoiddualsurfacefinish,compoundedeffectofcost,maskinganddefectrisk.


PROCESSOVERVIEWFlowChartforcostopImizaIon

ProcessOverview

StartwithInterconnect

budget

ReviewmaterialselecIonfortype

andsizeopImizaIon

OpImizestack-upforBOMcost

OpImizefeaturesizeforCpkmanagement

andConstrucIontype

ReviewFuncIonsinagivenboard

design


ProcessCostDriverDecisions•  AddiIonalLaminaIonsversusaddiIonallayers•  DrillSizeversusPadsizeopImizaIon•  PadSizeversusTraceSizeopImizaIon•  Movefinerlinestoinnernon-platedlayers•  Doyouneedboththroughandmicrovias?Microviacountscanbeincreasedwithoutcostimpact.AvoidaddiIonalplaIngsteps.

•  StackedorStaggeredVias(Filledornot)•  MatchedGlassStylestoreduceLayupError,IncreaseEconomyofScale


HIGHCOSTCHOICESPerformance,Dkandsize

HighCostChoices•  VIPPO–AddiIonalStepsEpoxyFill,PlanarizaIon,DualplaIngpasses,masking

MulIpledrillingpassesforfilledandnon-filledholes.•  SignalintegrityBenefits(NoDogbone),AssemblyLandIncrease,SupportedVia

withmaterialthatexpandsatsamerate.

TakecarefulconsideraIononadopIngthesedesignchoicesduetotheimpactoncost.AnalyzeandquanIfythebenefittojusIfythecost.


HDITypesExplained

Source:HDIHandbookDfXEngineering,LLC,2016

HDITypesExplained


Source:HDIHandbook

SequenIalLaminaIon



Back-Drilling



ProcessOverviewCostAdderimpactfromDesignChoices

DesignChoice AddedProcesses ApproximateCost

FactoronMFGcost

AddiIonalSTDLayer InnerLayerProcessing,RegistraIonBudget

8%

AddiIonalHDILayer AddiIonal,Lam,Laser,Plate

20%

DualSurfaceFinish Mask,Strip,Coat 15%(plusmetalareaCaclulaIon)

VIPPO EpoxyFill,PlanarizaIon,PlaIng

30%

SequenIalLaminaIon ThreeLaminaIonCyclesRegistraIon

50%

BackDrilling Drilling,Alignment,Cleaning

15%(basedonholecount)


dfx design for_cost

Devices & Hardware