Reliability investigation of low silver content micro-alloyed SAC solders

In our research, we performed comparative analyses concerning various lead-free SAC (SnAgCu) and micro-alloyed SAC (SnAgCu+Bi+Sb) solder alloys. The mechanical properties of these solder alloys were characterized by measuring the shear strength of 0603 (1.5 × 0.75 mm) size chip resistors´ joints. We designed a testboard, which contains fifty pieces of 0603 size resistors. Thirty of them are intended for shear strength measurements and the remaining twenty are intended for cross-sectional analyses. During the experiment, twenty-eight pieces of testboards were soldered (seven with each solder alloy) and twenty-four of them are subjected to Thermal-Shock life time tests with temperature range of +125°C - -40°C up to 2 000 cycles. The shear strength of the solder joints was measured on aged samples to examine their reliability as well. The detailed results are presented in the paper.