Effect of additive elements on tensile, creep and low cycle fatigue strength for SnBi solders

This paper presents tensile, creep and low cycle fatigue properties of three kinds of SnBi lead-free solders. Tensile, creep and low cycle fatigue tests were performed using miniature specimens of the three solders. The effects of additive elements on tensile, creep and fatigue properties were discussed. Three kinds of solders showed almost the same tensile strength of around 55MPa and the same tensile ductility of about 70%. The creep rupture lifetimes of Sn57.5Bi0.5AgCuNiGe were about 1.5 – 2 times longer than those of Sn58Bi and Sn57.5Bi0.5Ag solders at 313K, 353K and 373K. The three kinds of solders showed almost the same low cycle fatigue strength at 313K. These mechanical properties were discussed in relation with the microstructure.