Effect of Zn on properties and microstructure of SnAgCu alloy.

The microstructures, wettabilities and mechanical properties of SnAgCu-xZn (x = 0, 0.5, 0.8, 1.0, 1.2, 2.0, 2.5, 3.0) solders were investigated, respectively. The results indicated that adding small amount of Zn can evidently improve the wettability, mechanical properties and refine the microstructure of SnAgCu lead-free solder. However, there existed an effective range for the Zn addition, the best Zn content was found to be 0.8 % in the current study. Moreover, the presence of Zn in the solders plays a major role in inhibiting the growth of Cu-Sn intermetallic layer in the solder/Cu interface. Based on thermal-cycling tests, it is demonstrated that the addition of Zn can enhance the thermal-fatigue properties of SnAgCu solder joints. [ABSTRACT FROM AUTHOR]