Interfacial IMCandKirkendall voidonSACSolder Joints subject toThermalCycling

Theeffect ofThermal cycling onlead-free solder joints reliability wasreported. TheIMC compounds growth, Kirkendall voids formation andmterconnect failure mode arecharacterized onSAC/Cu-OSP interface. Thegrowth of interfacial CuSnIMCwasobserved after thermal cycling aging of500,1000cycles, andfaster IMCgrowth wasfound compared toisothermal aging withtheproposed comparison criteria. Kirkendall voids wereobserved after Ar+sputtering etching. Growth ofKirkendall voidduring TCaging was found intheCu3Sn layer oratCu-Cu3Sn interface. Coalesce ofvoids weakened theinterface anddecreased thedrop reliability significantly.