Electromigration Behavior of Low-Silver Sn-0.3Ag-0.7Cu-1.6Bi-0.2In Solder Joints

In typical service environments, high current densities pass through the interconnection leads of solder joints. The electromigration reliability of solder joints is thus of great significance. The microstructure, crystal orientation, and electromigration reliability of Sn-0.3Ag-0.7Cu-1.6Bi-0.2In solder were studied in this work. The results showed that the melting point of Sn-0.3Ag-0.7Cu-1.6Bi-0.2In solder is 212.3 degrees C, with good wettability. The addition of Bi and In reduced the melting point and undercooling of the solder, with improved solder wettability. Compared with Sn-3.0Ag-0.5Cu solder, the microstructure of the remelted solder was well distributed with fine grains. Compounds formed by substituting Sn atoms with In atoms. Among the linear solder joints, those made of Sn-0.3Ag-0.7Cu-1.6Bi-0.2In showed easier formation of polycrystalline structure, and the c-axis orientation of beta-Sn grains was more disordered. The addition of Bi and In to form Sn-0.3Ag-0.7Cu-1.6Bi-0.2In affected the formation and growth of intermetallic compounds and improved the electromigration reliability of solder joints.