Mechanical Performance of Polymer Cored BGA Interconnects

This paper presents the results from preliminary models comparing the mechanical performance of polymer cored BGA type interconnects with conventional solid solder BGA balls. The surface evolver was first used to predict the solder fillet shapes for use in the models. The mechanical behaviour of some candidate polymer spheres were also measured and the results of these measurements used to estimate the properties of the polymer. These results were then used together in the construction of preliminary elasto-plastic finite element models of the interconnects when subjected to cyclic shear loads. The results indicate that the polymer cored balls may potentially provide substantial improvements in solder joint fatigue life, but also indicate the significant effects that the design variables will have on the achievable benefits.