Insight into the preferential grain growth of intermetallics under electric current stressing – A phase field modeling

Abstract The preferential grain growth of intermetallics under electric current stressing has been observed and characterized in experiment, yet has to be understood mechanistically. This work employed a phase field model incorporating the effect of electrostatic free energy and grain orientation to investigate the growth behavior of intermetallics at the solder/Cu bonding interface under electric current stressing. It is demonstrated that the directional migration of grain boundaries and phase boundaries driven by the electromigration induces the preferential growth behavior of intermetallics with higher electric conductivity along the electron flow. It is revealed that faster phase boundary migration and growth of the intermetallic grain with higher electric conductivity is induced by the higher diffusion flux across the interface.