Phase equilibria of the Sn–Zn–Ag system and interfacial reactions in Sn–Zn/Ag couples

The phase equilibria of the Sn–Zn–Ag ternary system and interfacial reactions between Sn–Zn alloys and Ag were experimentally investigated at a specific temperature. Ternary Sn–Zn–Ag alloys were prepared and annealed at 260 °C to determine the Sn–Zn–Ag ternary system isothermal section. The experimental results reveal that no ternary compound was formed, and noticeable Zn solubility was observed in the Ag4Sn phase. Three Ag–Zn intermetallic compounds, AgZn3, Ag5Zn8 and AgZn, were formed on the Sn–9Zn/Ag interface at 260 °C. As the Zn content was gradually decreased in the Sn–Zn alloy, the intermetallic compound microstructures changed. If the Zn content was less than 2 wt% in the Sn–Zn alloy, Ag–Sn IMCs were then formed on the Ag surface and massive spalling of Ag–Zn IMC layers occurred from the Ag–Sn IMC surface.