Optimization of stress and related parameters of BGA solder joint with void defect under torsional load

In this paper, the BGA welding spot model with void defect is established by Ansys, and the stress simulation analysis and experimental verification are carried out by applying torsion load. The influence of BGA welding spot void size, welding pad size and PCB thickness on the torsion stress strain of welding spot with void is analyzed; Taking the void size, pad size and PCB thickness as variables, nine groups of solder joint models with different horizontal combinations are designed by orthogonal experiment method, and the corresponding torsion stress of solder joint is obtained. Based on the experimental data, the range and variance optimization analysis of the structural parameters of solder joint is carried out. The results show that the positions of the model stress are close to the torsion load, and the maximum stress of BGA welding spot with void defect occurs at the edge of welding spot; Under 95% confidence level, the void size of welding spot has the most significant influence on the welding spot; When the void diameter is 0.07mm, the pad diameter is 0.46mm and the PCB thickness is 1.4mm, it is the optimal welding spot structure parameter combination, and the maximum torsion stress of the optimal welding spot is reduced by 4.946Mpa.