Effects of board design parameters on failure mechanisms of PCB/BGA assemblies under drop impact

The dependency of the failure mechanisms of PCB/BGA assemblies subjected to drop impact on board designs variations is investigated in this study. Two key parameters are considered: the copper pad size and the trace routing. It is shown that the assemblies can exhibit various failure modes such as copper trace crack, pad cratering on PCB or crack at interposer on package side by varying these board design parameters, due to stress/strain redistribution in assembly, as well as the location change of the weakest link. The tradeoff between these failure modes during the design change is also investigated. With the help of finite element simulations, reliable failure indicators for each possible failure mode can be defined. With all these indicators considered, it is therefore possible to establish rules for predicting the failure behavior and the lifetime of PCB/BGA assemblies subjected to drop impacts, depending on the board layout.