Vibration test durability on large BGA assemblies: Evaluation of reinforcement techniques

The paper describes experimental and finite element modelling (FEM) analyses on BGA assemblies under vibration tests. The purpose is to evaluate reinforcement methods of large BGA submitted to vibrations. Two techniques are used in this test: a cord of glue around the BGA (`peel off joint'), and gluing all the ball matrix of the second level of the BGA (Underfilling). Comparison between SnPb and SAC alloy is also done. In all cases, failures mechanisms and Time To Failure (TTF) are compared. Failure analysis permits to follow the change in microstructure when solder balls are submitted to mechanical loading.