Effect of electromigration of Sn-xAg-Cu solder joints on its microstructure and mechanical properties

In this study, effect of electromigration of Sn-0.7Cu, Sn-0.3Ag-0.7Cu and Sn-3.0Ag-0.5Cu solder joints on the microstructure and mechanical properties were investigated. Within a certain range, addition of Ag enhanced the electromigration stressing resistance and the joint strength. Electromigration changed the distribution and morphology of the IMC. In cathode side, the Cu₆Sn₅ layer reduces with the increasing time, while in anode side, the Cu6Sn5 layer would increased with the increasing time. Electromigration reduced the mechanical properties of linear joints. The drop rate of ultimate tensile strength has a linear relationship with the stressing time. According to the fracture morphology, the fracture mechanism changed from ductile to cleavage fracture.