Study on microstructure and properties of SnBi36Ag0.5Sbx solder alloy

SnBi36Ag0.5Sbx (x=0.3, 0.7, 1.0, 1.5 and 2.0) solder alloy was prepared by melting pure Sn, Bi, Ag, Sb at 450 ℃ for 6 h and then casting at 320 ℃ according to the mass ratio. The microstructure, phase composition, melting point, wettability, and mechanical properties of the alloy were characterized to study the effect of Sb content on the properties of the alloy. The results showed that the alloy was composed of reticulated Bi phase, matrix phase of Sn, granular and short rod-shaped Bi-rich phase, and Ag₃Sn compound. In a certain range, most Sb elements solutionized in the matrix phase of Sn rather than as the SnSb compound liberation. The liquidus temperature and melting range of the alloy were increased by the addition of Sb. With increasing Sb content, the wettability decreased due to the worse wetting time and the wetting force. When the Sb content was 2%, the maximum tensile strength was 97.09 MPa. The addition of a small amount of Sb can significantly affect the properties of the Bi alloy solder in the Sn-Bi system.