Improving the reliability of ball grid arrays under random vibration by optimization of module design

In this work, three different arrangements of circuit board in an electronic device were designed and the effects of random vibration frequencies on the reliability of ball grid arrays (BGA) in these arrangements were evaluated. The failure criterion in solder balls was the root mean square of peeling stress exerted during the dynamical loadings. According to the finite element method (FEM) results, the uttermost stress concentration was generated at the interface of printed circuit board (PCB) and the solder balls. It was also revealed that the increase of input power spectral density (PSD) decreased the fatigue life of solder joint in all the arrangements. Considering the arrangements of circuit boards, it was found that the maximum domain of peeling stress had a minimum effect on the solder balls when the heat sinks were away from the packages. The microstructural characterization of critical zone in solder balls indicated that with the increase of maximum peeling stress, the crack initiated and propagated along the interface.