Wire Bonding TechnologyWord文件下载.docx

Wire Bonding TechnologyWord文件下载.docx

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Grade

Brokenat

Reason

Quality

1

Balllift

Badprocess

Poor

2

Ballneck

H.A.Z

Good

3

Wire

Dependsonconditions

Verygood

4

Weld

Welddeformation

5

Stitchlift

∙Wirediameter

∙Wirelength

∙Loopheight

∙Padtoleadplanegap

∙Hooklocation

∙

Testercalibration,accuracyandvacuum

3.ballheight（thickness）

ball（1stbond） 

3.Bottleneck（BTNK）CapillaryBonding

4.Bottleneck 

CapillariesTolerancesTable

Family/Design

BondPadPitch

SpecRange

Tolerances（mils）

Tip

Hole

CD

OR

4149X

4849X

Above

100um

Regular

ForTip>

10�0.3

ForHole≥2.5

+0.25/-0.1

�0.2

ForOR>

3.5

�0.3

ForTip≤10�0.2

For1.8<

Hole<

2.5

+0.2/-0.1

ForOR≤3.5

ForHole≤1.8

+0.15/-0.1

High

Spec

�0.1

-0.1/-0.0

5.Loopheight 

measuring

6.OpticalMeasurements

Usuallythisisthefirstsetofexaminationstobeperformed,usingaScanningElectronMicroscope（SEM）andadvancedopticalequipment.

Theseexaminationsareperformedbothpriortothebondingprocess-todeterminethebesttoolandprocessparameters-andafteritscompletion-toevaluatethebondingresults.Theseexaminationsconsistof:

∙Inspectionofthe 

package/devicedimensions,whichassistsinsettingtheprocessspecifications,determiningthewiringconstraintsanddesigningthebest-suitedcapillary.

bondpadandpitch 

andrelateddimensions,whichassistsindeterminingtherequiredbondpadopening,padsgap,padsizeandpadpitch.Thisalsohelpstodeterminethebondableareaandtherequiredcrosssection（accordingtopassivationlayer 

andpadlayerthickness）.

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 

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

1.20

1.70

1.40

1.10

1.60

1.00

0.90

0.80

0.95

0.70

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 

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