+0.2/-0.1
�0.2
ForOR≤3.5
�0.2
ForHole≤1.8
+0.15/-0.1
�0.2
High
Spec
�0.1
-0.1/-0.0
�0.1
�0.2
5.Loopheight measuring
6.OpticalMeasurements
Usuallythisisthefirstsetofexaminationstobeperformed,usingaScanningElectronMicroscope（SEM）andadvancedopticalequipment.
Theseexaminationsareperformedbothpriortothebondingprocess-todeterminethebesttoolandprocessparameters-andafteritscompletion-toevaluatethebondingresults.Theseexaminationsconsistof:
∙Inspectionofthe package/devicedimensions,whichassistsinsettingtheprocessspecifications,determiningthewiringconstraintsanddesigningthebest-suitedcapillary.
∙Inspectionofthe bondpadandpitch andrelateddimensions,whichassistsindeterminingtherequiredbondpadopening,padsgap,padsizeandpadpitch.Thisalsohelpstodeterminethebondableareaandtherequiredcrosssection（accordingtopassivationlayer andpadlayerthickness）.
∙Inspectionofthe wiringmeasurements,whichassistindefiningtherequiredballsize,ballheight,ballplacementaccuracy,loopheightandwireswaytolerances.
∙Thepostbondinginspectionsinclude ball（1stbond）diameter measuring, ballheight（thickness）measuringand Loopheight measuring.
7.BondPadPitch
Thebondpadpitchisadefineddistancebetweenthecentersoftwoadjacentpads.Thedesiredpadpitch,derivedfromtheapplicationconstraints,prescribesthetypeofcapillaryoneshoulduse.
Thecapillary'sexternaldimensions（Tip, BTNK, CA）needtobeoptimizedinordertoavoidcontactbetweenthecapillaryandtheadjacentwirewhilemaintainingoptimalbondingperformances.
8.The1stbonddiameterisderivedfromthe padopening.
Mostapplicationsrequirea100%bondonpad.Themostimportantcapillaryparameteraffectingthein-specaccuracyofthe1stbondisthe IC volume,whichconsistsofthe Hole diameter,the ICA and CD.
Thisparameterneedstobecarefullycontrolledandoptimizedinwaysthatshallbediscussedlater.
9.WireDiameter
Thewirediameterisdefinedbytheapplication-finerprocessesnaturallyemploythinnerwires.Therefore.thecapillary Hole isdefinedbythedesiredwirediameter.
Generally,thickwiresarepreferableduetotheirstrengthandbetterresistancetosweepduringmolding.However,thereisadelicatebalancebetweenHoleandwirethatneedstobeobservedinordertomaintainthecriticalgapthatallowsthefreeanduninhibitedmovementofthewire.Thiscriticalgapisimperativeforthesuccessoftheprocessandeliminatingincidentsofwireswayandwirefriction.
Anotherfactorinfluencingthewirediameterselectionisthecostofthe goldwire.
10.K&SCapillaryDesignRecommendations
WireDiameter（mil）
RecommendedHole（mil）
Min.RecommendedHole（mil）
2.00
3.00
2.40
1.50
2.20
1.80
1.30
1.80
1.50
1.20
1.70
1.40
1.10
1.60
1.30
1.00
1.50
1.20
0.90
1.20
1.10
0.80
1.00
0.95
0.70
0.90
0.85
11.TechnicalGuide
Goodbondingresultsaretheprimarygoalofeverybondingprocess.Theseresultsarethencomparedto thespecifications（SPEC）definedbythesemiconductormanufacturerandjudgedbytheirdeviationfromthatSPEC.
Thesemiconductormanufacturerseeksprocessreliabilityatlowercostsandhigheryields.Theseobviousbusinesstargetsareachievedthrougharepeatableandstablebondingprocess.Processstabilityismeasuredaccordingtothefollowingperformancespecifications:
∙FreeAirBalldiameter（min,max,std,Cpk）
∙Balldiameter&height（min,max,std,Cpk）
∙Loopheight&shape（min,max,std,Cpk）
∙Ballshearforce&Strength（min,Cpk）
∙Wirepullforce（min,Cpk）
∙Ballplacementaccuracy（min,Cpk）
∙Confirmationrun（stability,numberofassists,visualinspection, UPH）
∙Capillarydimensionstolerances（SPECs,effectonprocess,lifetime）
∙Overallprocessfeasibility（cost,demand,timetomarket）
K&SBondingToolshasdesigned advancedperformancetests todeterminewhetherspecificationsweremet.
Understandingtherelationshipbetweencapillarydimensionsandbondingresultsisthekeytocontrollingthebondingprocess.Everytoolhasmorethan15differentparametersthatdeterminethebondingresults.Theseparameters,alongwithvariousotherfactorssuchasthebondingmachine,thewireandthedevicemakeupthecomplexenvironmentthatinfluencestheprocess.ThisenvironmentisanalyzedbybondingexpertsinK&SapplicationlabsandR&Dcenters.Thefollowingisageneraldescriptionofthecapillary-processrelationsthatbynomeansconcludethebondingresultsanalysis.
12.BallShearTest
TheballsheartestisperformedusingaShearTester（BT-24,BT-2400PC,DAGE4000）andaShearTool.
Thetestisconsistentwiththefollowingmethodology:
1.Measureballdiameter（D）andballheight（H）,andthencalculatethe"bondedarea"（S）.
S=[（D^2）/4]*p in[mil]^2or[um]^2.
2.Fixshearheightaccordingtoballheightandpassivationthickness.
3.PerformShearforcetest.TheShearforce（F）ismeasuredin[gr.].
4.Theforcevalueobtainediscalculatedasfollows:
S/u_a（Shearperunitarea）=Shear/[pD2/4].
Reasonablestrengthrange=5.5andabove[gr.]/[mil]2
13.TheEffectonthe1stBond
The1stbondisprimarilyaffectedbythe IC.TheICcentersthe FAB priortotheformationofthebond,transmitsultrasonicpowertotheball,andhelpstocontrolthesizeofthebond.The CD andthe ICAdeterminetheICvolume,whichinturndeterminestheshape,diameterandstrengthofthe1stbond.
Therearetwomainfactorsaffectingthestrengthofthe1stbond:
1.TheforcevectorsappliedbytheICAand Tip face.
2.TheultrasonicvibrationsappliedtotheFAB,whichiscapturedintheICvolume.
TheICAalsoaffectstheforcevectorappliedonthegoldsquash.InmostcasesthelargertheICA,thehigherthepressureappliedonthesquash.
K&SBondingToolsoffersvariousICAsfordifferentapplicationrequirements,rangingfrom60°to130°.ThemostcommonICAdimensionsare90°and120°.The120°ICAisusuallyappliedtostandardapplicationswherealargersquashispermitted.The120°ICAallowsmoregoldtoflowoutsidetheIC,thusutilizingthetipfaceforastronger1stbond.
InFinePitchapplications,wheresmallersquashesarerequired,enlargedICvolumeisneededtocapturemoregold.Intheseinstances,90°ICAisappropriate.Inthiscase,theICvolumeisofmoreimportancethantheTipfaceasameansoftransmittingtheforceandultrasonicvibrationsneededtostrengthenthe1stbond.
14.TheEffectonLooping
Themaincapillaryparametersaffectingloopingarethe ICtypeandthe Hole.Toensurestablelooping,itiscriticaltoreduceoccurrencesoffrictionbetweenthewireandthecapillary.
Duringlooping,thewirecomesincontactwiththecapillaryalongtheHole,whentouchingthecorneroftheHoleandICandwhengoingthroughthecorneroftheICandthe Tip face.Whenexcessfrictionoccurs,thesecontactscanresultinwiredamageandloopsways.
ToavoidthesesetbacksinloopingoneneedstodefineanappropriategapbetweentheHoleandthewire,determinethebest ICA,andselectadditionalfeaturessuchas D/IC or IR.
Theminimumhole-wireclearanceisusuallysetat0.2milforFinePitchapplications;whenfinerclearancesarerequired,thereisdifficultyinreducinggapswithoutdamaginglooping.
Kulicke&Soffaindustry-leadingtolerancesallowsuchreductionswhilemaintainingastableprocess.
InStandardcapillarydesign,theloopheightdeterminestheCA,whileinFinePitchcapillarydesign,theloopheightdeterminesthe BTNKheight, BTNKangle andBTNKradius.
Forlongandhighlooping,aD/ICwitha90°or120°angleisusuallyrecommended.Forlongandlowlooping,anIRandICAof120°areadvisable.Naturally,theserecommendationsaresubjecttoapplicationconstraintsandoptimizationconsiderations.
15.TheEffectonthe2ndBond
Thecapillaryaffectsthe2ndbondintwomainaspects:
∙Thestitchbond-thisbondpermanentlyconnectsthewiretothelead.（Moreaboutthestitchbond）
∙Thetailbond-thisbondtemporarilyconnectsthewiretothelead.Itenablesthecapillarytorisetothetailposition,t
升级会员 