Mechanical properties of Pb Sn Pb In and Sn-In solders

The mechanical properties of eight solder alloys from the Pb-Sn-In-Ag alloy systems were determined over the temperature range -200°C to 100°C, using uniaxial tensile tests, dynamic mechanical analysis (DMA), acoustic pulse methods and dilatometry. In general, the strength and elastic modulus of the alloys studied was inversely dependent on temperature. PbSn, PbIn and SnIn alloys were observed to turn superplastic with elongations over 100 per cent at temperatures of 50°C or above. The Pb-based and In-Sn eutectic solders possessed superplasticity at temperatures greater than 50°C. From these results, deformation and fracture processes are reviewed, and the appropriate fracture mechanism is proposed.