焊线拉力检测

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1、UnderstandingtheWireBondPullTestByLeeLevinePresentedbyRayCathcartPurpose•Itmayappearthatthebonder/tool/wireisproducingweakwirebonds•It’simportanttounderstandthedataandthetestconditions•Thebondsmaybeweak,orthespecsmayneedtobecorrectedafterre-evaluatingtheprocess/

2、testmethods2SomeBasics•Themaximumforcethatthepulltestcandetectislimitedbythestrengthofthewire.•TheHeatAffectedZone(HAZ)abovetheballshouldbetheweakestpartofawirebond.•Boththeballandthewedgebondweldedareasareseveraltimeslargerthanthewirecrosssection.Ifthebondlifts

3、orfracturesattheinterfacethebondwasdefective.•Preferredfailuremodesareneck,midspan,heelofsecondbond,inthatorder.•Thebreakingforcemeasuredatthehookisnotthesameastheforceexertedonthewire.3PullTestResolutionofForces4SimplifiedEquationsforPullTest=F*M1=F*M25PullTest

4、R.O.F.SimplifiedF1=M1*FF2=M2*FwhereF=PullTestMeasurementF1,F2=Forceonthewireat1stor2ndBond6LowPullTestValues?•Do1stand2ndbondpulltests.Ifthevaluesareclosetothestrengthofthewire(80%)andthefailuremodeisgood(nolifts)thentheproblemisloopgeometry.•If1stor2ndbondpullt

5、estsareweak,orifliftsoccur,it’saparameterormaterialproblem.DOEsorplasmacleaningmayhelp.7LowLoopHeights(TSOPPackages)•M1&M2are>1;Range1-3•PullTestreadingsarelowerthantheactualforceinthewire•PerceptionthatbondsareweakMAYbeincorrectF1=M1*FF2=M2*F8HighorStandardLoop

6、Height•M1&M2<1•RangeforM1&M2.5to1.0•ForceinWireislowerthantheTestForce•IftheWireBreakLoadis10gramsthenthePullTestresultsarehigherthan10grams.F1=M1*FF2=M2*F9HookLocation•Midspanmeansthattheangleofthewireat1standsecondbondisequal,resultinginthesameforceineachleg.•

7、ItisNOTthemiddleofthelooplengthwhenthedieishigherthan2ndbond.•A10-20%deviationfrommidspandoesn’thaveasignificanteffectontheresults.10PullTestExcelTemplate8InputData7H10d2106h6lhp0ts7.55Pull-TestMid-Span4Xe40%hl84%3PullTestForce[grams]2100510152025303540455055657

8、07580859095100HookLocation[%ofdfrom1stbond]1stBondBreakForce2ndBondBreakForceXPull-TestMid-SpanPoint11Conclusions•Understandthegeometry.•Thegoalisstrongbonds,nothighn