Characterization of IMC layer and its effect on thermomechanical fatigue life of Sn-3.8Ag-0.7Cu solder joints

► The IMC microstructure and growth were studied under thermal aging conditions. ► The Young's modulus and hardness were determined for CuSn and CuNiSn IMC. ► Simulation results show that the thick IMC layer results in a lower fatigue life. ► The IMC layer with higher modulus results in a lower solder joint fatigue life.