Effect of Cu and Ni Addition on Microstructure and Wettability of Sn-Zn Solders

Abstract

In present study, Sn–9Zn, Sn–9Zn–xCu and Sn–9Zn–xNi solders (x = 1.0, 2.0 and 3.0 wt%) were prepared via melting process. Effects of Cu and Ni addition on microstructure, thermal behavior, wettability and corrosion resistance of Sn–9Zn solders were investigated. The experimental result showed that microstructure of the Sn–9Zn was composed of β–Sn and Zn–rich phases. Addition of Cu to the Sn–9Zn solders, Cu6Sn5 and Cu5Zn8 IMCs were observed. While addition of Ni to the Sn–9Zn solders, Ni3Sn4 and Ni5Zn21 IMCs were observed. It was also found that, amount of those IMCs obviously increased with increasing of Cu and Ni contents. The results obtained from thermal analysis showed that melting temperature of the Sn–9Zn solder was 199.6°C. While melting temperatures of the Sn–9Zn–1.0Cu and Sn–9Zn–1.0Ni solders were 199.9°C and 204.2°C, respectively. The Cu and Ni contents had little effect on both spread rate and wetting angle of the Sn–9Zn–xCu and Sn–9Zn–xNi solders. However, increasing of Cu and Ni contents significantly increased the corrosion potentials of the Sn–9Zn–xCu and Sn–9Zn–xNi solders.