2023 Volume 26 Issue 3 Pages 266-274
We investigated how adding Ni and Cu into Sn-6.4Sb-3.9Ag (mass%) lead-free solder affects its fatigue properties at high temperatures. The addition of Ni and Cu caused the formation of grains with high-angle grain boundaries and an increase in the number of grains. From the fatigue test, the solder with added Ni was confirmed to have superior fatigue properties at 175°C. The solder with added 0.4%Ni was confirmed to have the best fatigue properties. In contrast, in the solder with added Ni and Cu, the addition of 2.0%Cu in the solder degraded its fatigue properties at 175°C. From EBSD analysis, it was found that cracks grow at grain boundaries with dynamic continuous recrystallization in the solder with added Ni and 1.0%Cu. On the other hand, the fatigue damage in the solder with added 2.0%Cu was due to stress relaxation by dynamic recovery.
