Fracture Life Evaluation of Solder Joints in Semiconductor Structures Using Crack Propagation Analysis

In previous report, we proposed a new crack propagation model that could automatically calculate crack paths of micro-solder joints in semiconductor structures. In this report, we describe a fracture life evaluation method of micro-solder joints using our crack propagation model. When fatigue life is calculated using a finite element method (FEM), one of the most difficult issues is correcting for the effect of element size. We thus investigated the dependency of the calculated life on the element size and developed a formula for approximating this dependency. Using this formula, we could quantitatively estimate fatigue life regardless of element size. Calculation of the fatigue lives of ball grid array structures in which the diameters of the solder ball differed showed that the estimated life corresponded to the observed life.