Assessment of Solder Joint Fatigue Performance Using Cyclic Flexural Loading

The mechanics of solder joints in a surface mount assembly subjected to cyclic flexural load is examined using finite element method. A test assembly with peripheral-array solder joints is supported by eight pins and arranged in a circle on the component side of the printed circuit board (PCB). Cyclic flexural load to the assembly is achieved by prescribed displacement of the central loading pin. Flexural test cases were performed at temperatures 25, 42.5, 100 and 125degC. Results were compared with those of temperature cycling (Reference case), in terms of the rate of inelastic strain accumulation, stress-strain hysteresis loops and the predicted fatigue lives of solder joints.