SMT solder joint´s shape and location optimization using modified genetic algorithm in the dynamic loadings

Vibration fatigue has become an important factor impacting the SMT solder joint reliability and lifetime in dynamic loadings. In this paper shape and location optimization of SMT solder joints under vibration and shock conditions are investigated to raise their reliability and lifetime. A PBGA256 assembly is chosen to investigate the effect of shape and location of a SMT solder joint on its reliability under vibration and shock conditions. Then a modal experiment was performed to obtain the dynamic characteristics of the PBGA256 assembly. A finite element model, which is close to the PBGA256 assembly sample, is built based on the modal experiment. Then a modified genetic algorithm, which is a global optimization method, is used to perform shape and location of SMT solder joints based on the FEM of the PBGA256 assembly under shock conditions. The optimal results show the SMT solder joint with optimal location and shape has less maximum strain. As a result, reliability of SMT solder joint with those optimal parameters is better.