Study on Microstructure and Joint Strength of Sn-0.7Cu-0.8Zn/Cu Solder Joints by Bi Addition Modification

We have elucidated the roles of Bi addition in the melting characteristics, wettability, microstructure evolution, and mechanical properties of Sn-0.7Cu-0.8Zn/Cu solder joints. Melting properties analysis demonstrated that the melting point can be lowered by Bi alloying, while enhancing the melting range of the alloy. The wettability of the Sn-0.7Cu-0.8Zn solder first increased by a minor Bi addition and then decreased with the further increase of Bi content, and the wettability of the solder containing 1