Finite element study of chip package induced mechanical and corrosive failure modes complementing microstructural root cause analyses

Abstract

In automotive applications microelectronic components have to meet very strict reliability requirements. Additionally mechanical or thermomechanical stresses resulting from manufacturing processes or application conditions, as well as chemical influences have to be considered due to the exposure to harsh environmental conditions. In complex mounting situations or the use in harsh environments, e.g. humidity and corrosive compounds, even relatively simple devices (e.g. Hall sensors) can face complex failure modes. In these cases Finite-Element-Analyses (FEA) can support microstructural failure diagnostic methods and help to understand potential failure risks resulting from chip-package interaction effects (e.g. mechanical stresses resulting from the packaging process or different mounting situations). Such mechanical stresses do not only determine the risk of deformation-induced failure and cracking but can also affect the diffusion kinetics of chemical substances. This paper addresses chip-package interaction effects that determine the risk of chip damage by several failure modes. Results from microstructural failure analyses like scanning acoustic microscopy SAM, scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDX) where combined with FEA in order to understand the influence of different process parameters, mounting steps or material inhomogeneity's regarding the components reliability.