Coarsening in BGA solder balls: Modeling and experimental evaluation

The reliability of solder joints in electronic packaging is becoming more important as the ball grid array (BGA) develops rapidly into the most popular packaging technology. Thermal fatigue of solder joints has been a reliability concern in the electronic packaging industry since the introduction of surface mount technology (SMT). Microstructural coarsening (phase growth) is considered to be closely related to thermomechanical fatigue failure. Many researchers proposed coarsening models for bulk scale metals. But these models have never been verified for micron-scale actual BGA solder balls. In the present study, three different phase growth models are investigated experimentally on BGA solder balls in a real-life electronic package. Model simulations obtained from three models were compared against test data. The best performing model was chosen for finite element fatigue reliability studies based on continuum damage mechanics.