High temperature tensile and creep behavior of lead free solders

The mechanical behavior of lead free solders is highly dependent on the testing temperature. Previous investigations on mechanical characterization of conventional and doped lead free SAC solders have mainly emphasized stress-strain and creep testing at temperatures from 25 to 125 °C. However, solders are exposed to very high temperatures from 125–200 °C in several harsh environment applications including well boring, geothermal energy, and aerospace engines. In the current work, we have extended our previous studies to explore mechanical properties for SAC305, SAC_Q, SAC_R, and Innolot solders at temperatures from 125–200 °C at a strain rate of 0.001 (sec−1). The Anand constitutive model with parameters measured previously using test data from 25–125 has been shown to fit the high temperature stress-strain curves reasonably well. In addition, high temperature creep behavior of SAC305 was explored. Finally, the high temperature tensile properties of the above-mentioned solders have been compared. Our results show a significant degradation of mechanical properties of lead-free solders at higher temperatures. Also, a noteworthy increase in the secondary creep strain rate has been observed. Comparison of the results for different solders has shown that the addition of dopants (e.g. Bi, Ni, and Sb) in the traditional SAC alloys improve their properties significantly.