Shape prediction and residual stress evaluation of BGA and flip chip solder joints

In this paper, several solder joint shape prediction methods are studied. There are various methods to predict the solder joint shape, such as sphere approximation, analytical calculation based on equilibrium surface tension and another forces, and finite element simulation code like Surface Evolver developed by Ken Brakke. Authors calculate shapes of BGA and flip chip solder joints by three methods and confirm the validity of each methods. After that, we calculate solder joint residual stress at solder solidification process by general stress simulation FEM code for each solder shapes, and analyze the assembly parameters effects to the solder residual stress by statistic analysis.