Effect of Cu addition on Sn-9Zn lead-free solder properties

Reinforced Sn-Zn-based composite solders of in-situ IMC particle were obtained by adding Cu powders into Sn-9Zn melts.The melting behavior,microstructures,mechanical properties and the wettability to Cu of the solders were studied.The results show that the effect of a small amount Cu on the melting behavior can be negligible,but 3 wt.% Cu powder addition can increase its liquidus temperature.Cu₅Zn₈ particles are formed and distributed uniformly in the solders.The coarse rod-like Zn-rich phase decreases with the addition of Cu powder.The strength and plasticity of the solder are improved,and the creep resistance of the solder is considerably enhanced.Wettability of these composite solders is also better than that of Sn-9Zn.