SourcesofVoidsSourcesofVoidsN2(g)Chamber2Pressure=P2P1>P2LN2N2(g)Chamber1Pressure=P1Moltensolder在錫球生產過程中,會使用兩個壓力不同的Chamber,上方镕解槽C的壓力大于下方冷卻槽,并借著壓力差使镕融的錫從Chamber1被擠壓到Chamber2滴落,并在Chamber2冷卻成形在溶融的錫中,所有的氣泡都會因為浮力而懸浮在镕融的表面上,所以在溶融液中是沒有氣泡的镕融且未含氣泡的錫在冷卻階段隨著時間變成球形錫球生產的方式SourcesofVoidsPackagesideFluxPackagesidePackagesidePackagesidePackagesideBoardsidePasteBoardsideBoardsidePackagesideBubblePackageside芯片植球的過程芯片Mount在主板上的過程有機會消散掉三明治結構讓氣泡無法散去SourcesofVoids:EspeciallyforImAgBoardGalvanicCorrosion:電鍍銹蝕腐蝕當兩種不同的金屬直接接觸并曝露在水或含融鹽的水等電解質中，會產生電鍍銹蝕腐蝕。電流會在兩種金屬之間流動，類似電池的化學反應因而產生。兩種金屬之間的電位差越大，氧化的速度越快；反之，電位差越小，氧化的速度越慢。而銅與銀之間的電位差使得銅箔表面出現陷穴SourcesofVoids:EspeciallyforImAgBoardImmersionAgCucaveFluxIMCIMCIMC銅箔中的陷穴,導致了氣泡的生成IPC-7095B對錫球的描述TypeA:Void(s)withintheball(packagelevel)asreceived.TypeB:Void(s)attheball/packagesubstrateinterfaceasreceived.TypeC:Void(s)withintheballafterboardlevelassemblyprocess.TypeD:Void(s)attheball/packagesubstrateinterfaceafterboardlevelassemblyprocess.TypeE:Void(s)attheball/boardsubstrateinterfaceafterboardlevelassemblyprocess.VoidsclassificationinIPC-7095BMicroviaVoidsarecausedbythepresenceofmicroviasdesignedinthePCBlands.LargeMicroviaVoids,iflocatedinsolderjointsinhighstressareasofapackage,canimpactsolderjointreliability.MicroviaVoids是因為將微盲孔的設計應用在PCB板上所造成的.大型的微盲孔,如果位置是在芯片高應力區的錫球中,將會沖擊到錫球的可靠度IMCMicrovoidsoccurwithintheIntermetallicCompound(IMC)formedbetweencopperandhightinsolders,includingSACandtin/leadsolders.TheseIMCMicrovoidsdonotformimmediatelyafterthesolderingprocess,butafteragingathightemperaturesorduringtemperaturecyclingofthesolderjoints.Thetruerootcauseisstillunderinvestigation,butaKirkendallvoidingmechanismmayplayapart.Thesevoidscanaffectsolderjointreliability,particularlyininstanceswhenbrittlefractureisinitiatedwithintheIMCduringdropormechanicalshocktothesolderjoint.IMCMicrovoids通常發生在含錫量高的錫球中的IMC層內錫球與銅之間,包括Sn-Ag-Cu跟錫/鉛類的錫球.這類IMC中的Microvoids不會在焊接過程中立刻出現,但是會因為高溫老化或是高溫循環而出現.真正的根源仍在調查中,但是Kirkendall微孔形成機制可能在其中扮演了一部分的角色.這些Void會影響錫球的可靠度,舉個特別的例子來說,這些Void會在IMC層中成為摔落或沖擊測試時粒子破裂的起始點.PinholeVoidsarecausedbypinholesinthecopperlandsofthePCB.Withsufficientquantity,theycanaffectsolderjointreliabilityPinholeVoids是因為PCB板銅面上的針狀凸點或凹陷造成.如果數量夠多的話,會影響到錫球的可靠度VoidsclassificationinIPC-7095BIntelJGFabBSocketHX-sectionShrinkageVoidsComparisonbetweenDifferentSuppliers:FabAEllingtonBTHC9350000EE&EBTTM9370003DBTCBTJG9410002W在FabA,不同的Vendor所呈現的氣泡模式中,即可發現BTC與E&E不同,但也都出現在最具威脅性的IMC層上ComparisonbetweenDifferentSuppliers:FabBE&EBTJG9460000TBTCBTJG9410005G在FabB時,E&E的氣泡有了大幅度的改善,但是BTC的問題反而更加突顯了出來ComparisonbetweenDifferentSuppliers:FabC在FabC時,E&E跟BTC的氣泡問題,都獲得了很大的改善BTCBTJG9490001NE&EBTJG9490001VE&EBTJG94900