Life prediction of BGA and CSP assemblies using an experimental degradation law and FEM simulations

BGA and CSP packages are now commonly used because of their capabilities to provide more I/O connections than standard leaded SMT components for the same surface. To evaluate the reliability of assemblies using these packages, we propose a life prediction method: it uses a degradation law based on experimental analyses of the evolution of the eutectic microstructure under thermal cycling, and 3D FEM simulations used to determine the maximum strain in the solder joint. The results are compared with an analytical model that provides a fast classification of different assemblies with regard to their thermomechanical behavior.