半导体封装刷胶汉高WBCCapabilityinChina

WBCTrainingNotesTonyWinster,AblestikU.K.21June2008Project:TWIR-7FPB92WaferBacksideCoating(WBC)---IntroductionandCapabilitySet-upinChinaYoungXUESr.TechnicalServiceEngineerJuly15,2008XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina2BackgroundAblestikintroducesanewlineofspeciallydesignedadhesivesthatcanbeappliedtothebackofawaferanddried.Conductiveandnonconductivewaferbacksidecoatingmaterialshavebeendevelopedfordiesizes3mmorlessandenablesuchpackagetypesasCOL,SO,TSOPandQFN.HighthermalmaterialshavebeendevelopedthataresuitableforuseindiscreteandsmallpowerICdevices.Theadvantagesofthewaferbacksidecoatingprocessare:*Bondlinethicknessandfilletformationcanbecontrolled*Resinbleediseliminated*Moistureresistanceandadhesivestrengthareimproved*WBCmaterialscanachievehigherreliabilitylevelsXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina3WBCProcessIntroductionWBCProcessIntroductionXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina4WBCProcessOverviewWBCprocessutilizesexistingdownstreamDieAttachinfrastructuWBCprocessutilizesexistingdownstreamDieAttachinfrastructurereandrequiresonlystandard,readilyavailableprintingmachines.andrequiresonlystandard,readilyavailableprintingmachines.XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina5WBCMerits-1WBCProcessPasteProcessWBCcanoffersignificantprocessbenefitsatleast20WBCcanoffersignificantprocessbenefitsatleast20--30%cheaperthanfilm.30%cheaperthanfilm.ICApplication™LeadframestandardizationNoneedfordispensing;glueisalreadyon100%ofthechipatthedesiredthickness™ImprovedreliabilityregardlessofLDFtypeL1,260cpossibleonAg,Cu,PPFandAolly42™ImprovedyieldsReduceddietilt;Nobleeding™ImproveddesignflexibilityTighterdiebondtopadratios;AbilitytochoosethicknessXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina6WBCMerits-2WBCcanbedroppedintoexistingsoftsolderandeutecticlines.WBCcanbedroppedintoexistingsoftsolderandeutecticlines.™Discrete/SmallSOApplications----Eutecticandsoftsolderishighstress.WBCcanimprovereliabilitybyreducingcracks----EliminateN2orH2forminggassesduetolowertemperaturecure™Eutectic----Reduceandstandardizebacksidecoatinglayer™SoftSolder----Increaselinespeedsby2-3times----Pb-freedieattachsolution(Typicallysoftsolderis95%Pb)XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina7WBCWaferBackSideCoatingStencilPrintingScreenPrintingSpinCoatingAblestikhasthreemethodstoachievewaferbacksidecoatingproAblestikhasthreemethodstoachievewaferbacksidecoatingprocess.cess.XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina8StencilprintingVacuumtubeSqueegeePalettePalette™Stencilprintingismainlywaferbacksidecoatingmethodrecommendedtocustomer.™Stencilprintingisabletoprovidesmoothsurface(goodperformanceinroughness)andhasgoodthicknesscontrol.Moreover,itsprocessisstableandeasytocontrol.™Stencilprintinghasastrictrequesttoshimandstencilthicknessuniformity.Inaddition,theflatnessofpaletteandsqueegeearekeyfactorsforprintingperformance.XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina9Stencil™Forthickercoating(1mil),itistypicallyrecommendedtouseopencutstencils.Opencutisbigopeninginthemetalstencil.™Stencilopeningcanselectedbasedontheprintarearequirements.Typicallyopeningwillbe2mmlessthanthewaferdiameter.(Example:198mmopeningfor200mmwafer).™Stencilthicknessdependsonthecoatingthicknessrequirement.™Forthinnercoating(≤1mil),screensarerecommended.FrameFrameMetalMetalOpeningOpeningXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina10Shim™Shimsarerecommendedtoreducethestencildeflectionduringprinting.™Printinguniformityacrossthewaferisimprovedusingshims.™Shimismetalsheetwithopeningofwaferdiameter+1milandthicknessequalstothewaferthicknessoralittlerlower.waferStencilMetalShimWaferbacksidematerialwaferStencilMetalShimWaferbacksidematerialXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina11Squeegee™Rollbarsqueegee(ormetalsqueegeewithreinforcedrodattheedge)isrecommendtoreducethescoopingduringprintingwithbigopeningstencils.™Rollbarsqueegeeisnotrecommendedforscreenprinting.™Rubbersqueegeesormetalbladearerecommendedforscreenprinting.waferStencilMetalShimWaferbacksidematerialSqueegeeXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina12RollBarSqueegee™Rollbarsqueegeeisveryrigidanditcanofferperfectflatperformanceascomparedwithmetalbladeandrubbersqueegees.™RollbarsqueegeewasdevelopedbyDEKandAblestikTStogether.Anditsdesignwasprotectedbypatent.XUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina13PaletteVacuumtubeSqueegee™Printingbacksidecoatingonwafersrequiresvacuumchucktomakethewaferstable.™Paletteneedstobeverysmoothandflatsoasnottodamagethefrontfaceofthewafer.Besides,theflatnessofpalettewillcauseprintthicknessvariation.™Granitepaletteusuallyshowsbetterperformancethanmetalpalette.Butitsweightisreallyhighanditmaycausenegativeeffectonprinter.PalettePaletteXUEYoung---WBCGeneralIntroductionandCapabilitySet-upinChina14SketchofstencilprintingSqueegeePalettePaletteVacuumtubeNoadhesivearoundwaferXUEYoung---WBCGeneralIntroductionandCapabilitySet-