SPT-wirebonding-technology

AdivisionofSPTRothGroupWireBondingTechnologyWireBondingProcessAprocessofinterconnectingthebondpadmetallizationtotheleadpostwithaconductingwiresoastocompletetheelectriccircuitbetweenthechiptotheleadexternaltothepackage.WireBondingProcess(Cont.)BGAQFPWireBondingProcess(Cont.)QFNSmartCardThreetypeofW/BprocessesThermosonicbonding/ballbonding-Heatandultrasonicareappliedtobondtwodifferentmetallicsurfacesunderpressuretoformabond,morethan90%ofallsemiconductorpackagesiswiththisprocessThreetypeofW/BprocessesUltrasonicbonding/wedgebonding-UltrasonicenergyisappliedontwometallicsurfacesunderpressuretoformabondThermalcompressionbonding-Seldomusedtoday,butistheoriginaltechnologydevelopedbyBellLabsin1957forelectricalinterconnectionDifferencesBetweenT/S(ThermoSonic)andU/S(UltraSonic)T/SU/SWireAu/CuAl/AuToolCapillaryWedgeBondingTemp.NeedHeatingRoomTemp.BonderNeedEFODon’tneedEFOLoopingLoopingnon-directionaldirectionalBallBondingSequenceBallBondingSequence(Cont.)BallBondingSequence(Cont.)BallBondingSequence(Cont.)FirstbondKeyattributeszBondpower/force/timezBondtemperature(thermosonicbondingonly)zBondpadmetallizationtypezCapillarydesignzPRSperformanceKeyeffectszBallshape(size,height)zBondstrengthzCrateringzBallplacementBallBondingSequence(Cont.)BallBondingSequence(Cont.)LoopingKeyattributeszWire(type,size)zTooldesign(clearancebetweentoolinnerdiameterandwire)zLoopingalgorithm/WirefeedingsystemzHAZzWirespoolingKeyeffectszLoopheightzWireswayzWiresaggingzWiresweepduringmoldingBallBondingSequence(Cont.)BallBondingSequence(Cont.)SecondbondKeyattributeszBondpower/force/timezBondtemperature(thermosonicbondingonly)zLFsurfacezLFclampingzCapillarydesignKeydefectszLiftedpostzSmashbondzBrokenwireBallBondingSequence(Cont.)BallBondingSequence(Cont.)FirstbondpreparationKeyattributeszWiretaillengthzEFOsettings(ballsizeratio/torchcurrent,torchtime)zEFOgapzThesurfacetensionofthemoltenmetalmaintainsasphericalshapewhilethewirecoolsandsolidifiesKeyeffectszToosmallballwillresultinpluggingthecapillaryzToolargeaballmayresultinmore“misplace”bondzClubballT/SBondingMechanismThewirebondprocessinterconnectthebondpadmetallizationtotheleadpostwithaconductwire.Thiscompletestheelectriccircuitbetweenthechipandtheleadexternaltothepackage.T/SBondingMechanismWhentwometal,suchasgoldandaluminum,isincontactduringbondingwiththepresenceofheat,ultrasonicpower,impactforceandothers,metalsaresoftenedanddeformedandaprocesscalleddiffusionimmediatelystartsbetweenthetwometalsandformintermetalliccompoundsorjustalloy,whichensureareliableelectricalconnection.T/SBondingMechanism(Cont.)1stBond(Ball)2ndBond(Stitch)TemperatureTemperatureUSUSForceForceTTUSUSFFT/SBondingMechanism(Cont.)BondForceHoldtheballorwireinpositionforultrasonicenergytransferForceonthetopofwirecausesthewireandbondsurfacetobetightlyjoinedtogetherandexpendedoutwhenstretchedThestretchingbreakupcontaminationoneachsurface,causingpuregoldtobeexposedWhenpuregoldfromthewireandthebondsurfacecontacteachother,amolecularbondisbondT/SBondingMechanism(Cont.)UltrasonicPowerInterdiffusionofatomsacrossthematinginterfaceCausesthebondingwireandthebondsurfacetosoftenAverysmallamountofheatiscreatedinthebondfromtheultrasonicenergyUltrasonicenergyisproportionaltothehorndisplacementHigherultrasonicenergy,largerdisplacement,largerballsizeT/SBondingMechanism(Cont.)Temperature(Heat)Heathelpstoremovesurfacecontamination,suchasabsorbedmoisture,oilsandvaporHeatalsohelpstoincreasetheabilityofgoldatomstoflowandbondwithotheratomsT/SBondingMechanism(Cont.)BondTimeTimeisthefactorthatcontrolshowlongultrasonicenergyisonduringtheprocessofmakingabondTimesettingrangefromaslowas1msecto255msecItwillnotbepossibletobondattoolowanultrasonictimeCapillaryDesignCapillaryMainDimension-StandardCapillaryDesignCapillaryMainDimension–BottleNeckCapillaryDesign(Cont.)MaterialSPTwirebondingcapillariesareformedoutofanultra-pureAl2O3finegradeceramicpowder-high-densitymaterialfornon-finepitch,andforcompositeceramic(AZ)materialforultra-finepitchapplications.HighDensityCeramicCompositeCeramicCapillaryDesign(Cont.)ManufatureProcessSPTCIM(CeramicInjectionMolding)vs.GrindingCapillaryDesign(Cont.)ManufatureProcess(Cont.)CapillaryDesign(Cont.)CapillarydimensionimpactonbondingcharacteristicCapillaryDesign(Cont.)H:HoleBallSizeLoopingBuildupRecommend:H=1.4WDFinePitch:H=1.3WD(min)UltraFinePitch:H=1.2WD(min)CapillaryDesign(Cont.)CD:ChamferDiameterLargerCD,higherball/shearLargerCD,smallerstitchbondBallcentering,ballsizeMBD(min)=CD+10%CD=H+10um=H+8um(finepitch)CapillaryDesign(Cont.)CA/IC:ChamferAngle/InnerChamferFABcenteringBallsize/BallshapeBallstrengthTailbondstrengthCapillaryDesign(Cont.)T/FA/OR:Tipdiameter/faceangle/outradiusStitchlengthHeeltransitionBuild-uprelatedlifespanRecommendation:-SelectthelargestT-largerORwithsmallerFA,viceverseSLTFAORCapillaryDesign(Cont.)BondingpadpitchlimitationontipsizeNewCapillaryRequirementChecklistItemExampleApplication:QFPLeadCount:208WireMaterial/Diameter:Au1.0milBonder/Model:ESEC3088BondPadOpeningSize:80umPadPitch:90umLoopHeight(target):200umMa