Thermal Reliability Analysis and Structure Optimization of BGA Solder Joint Based on Genetic Algorithm

Due to the miniaturization of electronic packaging devices, the reliability of solder joints is required to be higher. The thermal fatigue failure of solder joints is very prominent due to the mismatch of thermal expansion (CTE) between solder joints and matrix under the action of temperature cycling load. In this paper, ANAND model is used to describe the mechanical behavior of BGA solder joint and finite element analysis of BGA solder joint model under thermal cycle load is carried out based on ANSYS software. The stress and strain distributions of the solder joints were obtained. The sub-model of the key solder joints was established, and the IMC layer structure was added between the solder ball and the solder pad, and then the solder joints were analyzed by mesh refining to predict the thermal fatigue life of the solder joints. The mapping relationship between fatigue life and structural parameters of solder joints was build by response surface method, and the regression equation was obtained by fitting. Then, the structure of solder joint and the thickness of PCB were optimized by genetic algorithm. Finally, the optimal structural parameters of solder joint were obtained and the simulation bear out the effectiveness of the optimization.