Wettability, interfacial reaction and mechanical properties of Sn/Sn–CuZnAl solder and Cu sheet during solid–liquid diffusion

In the present study, the effects of CuZnAl particles on the wettability, interfacial reaction and mechanical properties of Sn/Cu solder joints during solid–liquid diffusion were investigated. Results show that adding 0.5 wt% CuZnAl particles significantly improved the wettability of Sn solder joints. Increasing the heating temperature or adding N₂ atmosphere can also enhance the wettability of the solder joints. The formation and growth of interfacial intermetallic compounds were inhibited by adding CuZnAl particles. For Sn and Sn–0.5CuZnAl solder joints, the diffusion coefficients of Cu₆Sn₅ were calculated to be 0.01 μm² s⁻¹ and 0.007 μm² s⁻¹, respectively. The diffusion coefficients of Cu₃Sn were calculated to be 0.0013 μm² s⁻¹ and 0.0012 μm² s⁻¹, respectively. In addition, the mechanical properties of Sn–0.5CuZnAl solder joints were better than that of Sn solder joints.