Solder joint reliability evaluation of chip scale package using a modified Coffin–Manson equation

Thermal cycle tests were performed for chip scale package (CSP) solder joints with Sn–37mass%Pb under several thermal cycle conditions. Under the conventional thermal cycle conditions, which heat up to approximately 100 °C, microstructure coarsening occurred and solder joints were fractured. The thermal fatigue lives followed the modified Coffin–Manson equation. The exponential factors m and n, and the activation energy Q in that equation were evaluated as 0.33, −1.9 and 15.5 kJ/mol, respectively. When the maximum temperature is room temperature and the temperature range is very narrow, the solder joint fracture occurred without microstructure coarsening, and the thermal fatigue life does not follow the modified Coffin–Manson equation.