On the role of electromigration in power cycling tests

Effects of electromigration on microstructures of solder interconnections during electrical current stressing have been widely reported. However, a more profound understanding of the role of electron flow in the evolution and mechanical integrity of intermetallic layers is needed. Therefore, in this paper the effects of cyclic power loads on the evolution of solder interconnection interfacial microstructures are presented. It is shown that the direction of the electron flux significantly affects on the growth kinetics of Cu₆Sn₅ and Cu₃Sn intermetallics. In addition, there is a clear difference between constant and cyclic electrical loading conditions. Furthermore, the microstructural evolution caused by electromigration and thermomechanical loads has a significant effect on failure mechanism under fast mechanical loading i.e. drop testing.