Abstract
The purposes of this study are to clarify the dynamic behavior of BGA or CSP packaging subjected to an impact loading, and to establish a simple analytical method of impact reliability assessment for solder joints. In this study, the repetitive drop test was carried out to observe the crack propagating processes. From the results of the repetitive drop test, it was found that the dynamic fatigue crack concentrates at the interface between the copper pad and solder bulk. And a large plastic deformation domain was not found around the crack tip. So the authors evaluated the crack growth based upon the elastic fracture mechanics theory. As an analytical method, 3D analytical models with the crack tip were used for the elastic FEA to calculate the stress intensity factor K_I. And the authors showed a policy that the fatigue failure life of the solder joints could be evaluated by the application of the Paris' law.
