Impact of isothermal aging on Sn-Ag-Cu solder interconnect board level high G mechanical shock performance

The mechanical stability of solder joints with Sn-Ag-Cu was an issue since the material was applied to the consumer electronic field. Various shock test methods were developed and standardized tests are used in the industry worldwide. Although it is applied for several years, the detailed mechanism of the shock induced failure mechanism is still under investigation. The work reported here concerns the root cause of shock failures with High G shock, the joint stability under various strain and shock level combinations and the impact of isothermal aging on board level shock performance. A test vehicle is developed to have various strain and shock level conditions in one board. Along with no aged 17×17mm CABGA package samples, isothermal aging were applied to the samples to observe the impact of different interface microstructures. The result revealed a clear indication of the strain and shock correlation with a trend of isothermal aging induced degradation. The impact of isothermal aging, strain and shock level on two different pad designs, non solder mask defined and solder mask defined are also discussed.