Effect of Sb addition on Bi–2.6Ag–0.1Cu solders for high-temperature applications

Abstract

The wetting, microstructural, and mechanical properties of Bi–2.6Ag–0.1Cu solders were investigated with various Sb contents. The Bi–Ag–Cu–xSb (x=0, 0.5, 1, 1.5, 2) alloys satisfied the optimum melting range of 261–275°C suitable for high-temperature applications. The microstructure of the Bi–2.6Ag–0.1Cu solder indicated a nearly eutectic mixture. Addition of Sb to the Bi–2.6Ag–0.1Cu solders resulted in the formation of intermetallic compounds such as η, ζ, and ε phases. In addition, the volume fraction of eutectic region decreased with increase in Sb content, together with the transformation of ζ phase to a larger-sized ε phase. The wetting angle of Bi–Ag–Cu–xSb solders on Cu plate was found to improve with increase in Sb content and test temperature. The Sb content contributed more significantly to the wettability than the test temperature. Furthermore, the hardness of Bi–Ag–Cu–xSb solders was found to increase with the Sb content. However, the addition of Sb deteriorated the electrical resistivity of Bi–Ag–Cu–xSb solders.