Effect of temperature on tensile properties of high-melting point Bi system solder

摘要

Tensile properties of three Bi-bearing lead-free solder were investigated and compared with that of Pb-rich Pb-2.5Ag-2.5Sn (mass%) solder. Tensile strength decreases with increasing temperature in all solder investigated. Although tensile strength of Bi-bearing solder is lower than that of Pb-2.5Ag-2.5Sn at 25°C, tensile strength of Bi-1.0Ag-0.3Sn-0.03Ge (mass%) and Bi-2.5Ag (mass%) are analogous to and higher than that of Pb-2.5Ag-2.5Sn respectively at a temperature of 125°C or more. 0.2% proof stress of Bi-2.5Ag increases with increasing temperature. Although the proof stress of Bi-2.5Ag is the lowest at 25°C, it was the highest at 125°C and 175°C among solder investigated. Elongation of Bi-bearing lead-free solder improves with increasing temperature. In particular, the improvement of elongation of Bi is significant and it improves up to approximately 60 % at a temperature of 125°C or more.