Duplicable and effective — A new drop test for BGA assemblies

Drop test performance is a key parameter for electronic packages such as ball-grid array (BGA) used for mobile and handheld applications. To get a repeatable and reliable test result, this paper introduced a modified method based on the currently widely used drop test method, JESD22B111. This method includes a totally symmetric layout so that all BGAs are at the same stress level and same failure probability during the drop. In order to get a consistent reliability result, the drop shock pulse was also clearly defined after analyzing all test results from different test labs with different drop testers. It was found that key parameters to define the failure are acceleration amplitude and velocity change or Delta-V. Delta-V represents energy dissipation during the drop cycle and plays a key role but is often neglected. This study has demonstrated that delta-V needs to be the same to get the same characteristic life of BGA solder joints for a given acceleration amplitude. Furthermore, the calculation of delta-V has been discussed which is critical for the shock pulse using profile other than half-sine shape.