Effects of Electromigration on the Creep of Sn0.3Ag0.7Cu Solder Joint

For real solder joints used in electronic devices, EM and creep may be two relevant reliability problems because solder joints usually serves under a combination of current stressing, elevated temperatures, and mechanical loading conditions. Especially when the size of solder joints scales down and current density escalates, EM-induced microstructure change should have certain impact on creep behavior. In this study, we analyzed and discussed how EM influenced the creep behavior of lead-free solder joint from the perspective of EM-induced IMCs change. Behaviors of both interfacial and matrix IMCs were observed and attempt to reveal the roles they played in the failure of real lead-free solder joint. From this study we can conclude that: during EM, grain size of interfacial IMCs at both sides was increased, and the size at anode side was much larger. The shape of interfacial IMCs was changed from scallop shape to hexagonal prism. Besides, there were many Cu6Sn5 migrated into solder matrix. During creep, pre-EM process alleviated deformation of solder matrix and brought about brittle fracture of a solder joint.