The morphology change of SnAgCu solder under current stressing

Special specimen was designed to study the morphology change of SnAgCu solder under the influence of electromigration (EM) alone. High current stressing was applied to the specimens so that EM of solder would happen at both room and high temperatures. The interfacial crack at cathode is the main failure mode, although the positions of crack maybe different under different temperatures. Localized hillocks were observed at anode and central part of solder at room temperature. But at high temperature, localized hillock was not observed, instead, the solder "surge" toward anode, what\´s more, it is found that the morphology of Cu3Sn changes from layer to scallop so that it loose its function as a barrier Cu migration. Evolution of the temperature field and plasticity deformation of solder during current stressing were observed, which can be served as basis for damage evolution of solder.