jac 2016 chua microstructural sintered ag
TRANSCRIPT
Ref:JAC,2016,687,486-498.DOI:10.1016/j.jallcom.2016.06.132
1. Agsubstrate:DSSincreaseaFer50-100hrs,maintainedfor500hrs.2. DBCsubstrate:DSSmaintainedfor500hrs.3. Cusubstrate:DSSdeteriorate50hrs.4. ThicknessofallAgjointsreducedregardlessofsubstrates.
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(A)Assintered(B)Aged24hrs(C)Aged50hrs(D)for500hrs
VoidlessCu2ObetweenCusubstrateandAgplaSng 3
(A)Assintered(B)Aged24hrs(C)Aged50hrs(D)for500hrs
Cu2OreachescriScalthicknessaFer50hrsofaging;CTEmismatchandKirkendallvoidscauseinterfacialseparaSon. 4
1. RaforDBCis600nmvsfor70nmCu&2. CTEmismatchislesserforDBCimprovestheshearstrength/3. CTE(ppm/OC)forDBCalumina(7),Cu(17),Cu2O(4.3)andAg(19.5) 5
(A)Assintered(B)Aged24hrs(C)Aged50hrs(D)for500hrs
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xn=ktx=k’tm
x=equivalentthicknesst=Sme
k&m=constant.(Normalized)thicknessofCu2OforAgandDBCsubstratesconformswiththepowerlawBUTnotparabolici.e.0.18<m<0.34m=0.5forparabolic
7CorrelaKonNOTcausaKon.ShearStrengthcorrelatedtoincreasingCu2ObutcausedbydensificaKon(page2)Fun-fact:checkoutthishRp://www.tylervigen.com/spurious-correlaKonsforspuriouscorrelaKon
ReducKoninporosity(%)
Frequencyofporeswithirregularshape
(0.1<f<0.4)increasebutmajorityissKll
regular-shape(circular)pores(0.9<f<1.0)
ReducKoninbigpores
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1. Ag-plated substrate: void-less diffusion microstructure; increase of shearstrengthwithagingfor500hrs.
2. Cusubstrate: thickCuoxideseparaSngthebondingbetween50-100hrsofaging.
3. DBCsubstrate:RoughDBCandmatchingCTEmaintaintheshearstrength4. IncreaseofshearstrengthcorrelateswithCu2OthicknessbutREALLYCAUSED
bydensificaSonofsinterednano-Ag5. Thickness(normalized)ofCu2OforAgandDBCsubstratesconformswiththe
powerlawBUTnotparabolicrate.6. OnageingforONLY50hrsat300oC,reducSonofporosity(densificaSon),
1. ReducSoninporosityand2. increaseinporeswithirregularshapeBUT3. regularporessSllthedominantshape.
7. IMPLICATIONS: DBC is sSll theway to go for powermodule; Ag plaSng isneededforlead-framepackagebutthethicknessisimportant.
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Pleasekeepalookoutforourupcomingpaperon1)“reliabilityofsinteredsilver(nanoandmicron-Ag)underthermalcycling”,and2)do read our recent review on “patents related to sintered silver as die-aRachmaterials”inJEP(ASME)selectedasoneofeightIBM’spickfor2014-2016.If you have any comments and quesSons, please feel free to write to me [email protected]@gmail.com
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