Experimentally validated analysis and parametric optimization of mechanical shock testing of advanced BGA packages

With continuing miniaturization and more prevalent use of Ball Grid Array (BGA) packages in the microelectronics industry, the mechanical strength of Printed Circuit Board Assemblies (PCBAs) with BGA packages is becoming very critical. In a variety of applications ranging from smart phones to high end switches and routers, the mechanical robustness of PCBAs is becoming the key differentiator in product reliability. IPC/JEDEC-9704 test method was developed several years ago to enable a standard way to benchmark mechanical reliability. The test method has helped compare different PCBAs to optimize overall mechanical reliability. However, a key challenge with mechanical shock testing is that by the time the testing is performed, it is too time consuming and expensive to make changes to the package if its mechanical reliability needs improvement. In this study, shock tests for various BGA packages have been conducted based on the IPC/JEDEC-9704 standard, under different applied G values to obtain the required data for studying the failure modes. Threedimensional Finite Element Models (FEM) were developed to understand the relationship between PCB strain and corner solder joint strain. The strain values on the PCB close to the package were estimated from the model and compared with experimental data. A series of FEM analyses were performed with different design parameters. Finally, based on the results presented in this study, optimization analysis was performed to improve BGA mechanical reliability for any given geometry.