Grain growth in eutectic Pb/Sn ball grid array solder joints

The reliability of solder joints in electronic packaging is becoming more important as 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). Micro-structural coarsening (grain growth) is considered to be closely related to thermo-mechanical 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 grain growth models are investigated experimentally on BGA solder bails 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.