A novel shock life model for BGA solder joints based on EPSD

Abstract

A novel shock life model is proposed for ball grid array (BGA) solder joints to evaluate its life under shock loads based on the evolutionary power spectral density (EPSD). Considering the bandwidth and non-Gaussian features of the stress signals during different stages, the shock stress response was treated as a non-stationary and non-Gaussian stochastic process. EPSD of the shock stress response is derived in matrix form based on wavelet transforms. The weight coefficient and non-Gaussian damage factor are proposed to describe the influence of the bandwidth and non-Gaussian characteristics of shock response on damage, respectively. The damage values of different stress stages were calculated by weight coefficient and corrected using non-Gaussian damage factor. Then the shock life model is proposed based on damage accumulation theory. Tests for the BGA solder joints shock life were conducted, and the result shows the proposed model is feasible.