Usage of Fracture Mechanical Integral Concept T* in Microelectronic Packaging Technique

Usage of the fracture mechanical integral concept T by FE-analysis allows the investigation of the propagation of damages and the estimation of long time reliability. An advanced program is developed to calculate the T-integral by a commercial FEM-tool. As an example the application of this integral concept is demonstrated in the simulation of a global model of a BGA (Ball Grid Array) construction under thermal cycling load. The outermost balls at the corners offer the highest stresses. Then a local model of the outermost ball is simulated, where a tiny crack is set in a critical zone that contains the highest stress. The possibility of propagation of this crack can be investigated by the T-integral. To estimate the speed of fatigue crack propagation a concept exists and is presented.