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

• Sb addition increased the liquidus temperatures suitable for high temperature solders.
• Different solidification microstructure as compared with the phase diagram.
• The wetting angle on Cu was improved with increase in Sb content and temperature.
• Sb contents had more impact on the wettability than the test temperature.

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.

Wettability of Bi–2.6Ag–0.1Cu–xSb alloys; (a) wetting angle and (b) multiple regression analysis as a function of temperature and Sb content. The wetting angle of the Bi–2.6Ag–0.1Cu–xSb solders on Cu plate was improved with increase in Sb content and test temperature. The contribution of the Sb content on the wettability was more significant than that of the test temperature.Figure optionsDownload as PowerPoint slide