Thermo-mechanical stress induced by CPI on 3D interposer package

Abstract

In this work Finite Element Modeling (FEM) is used to investigate the stress and deformation induced by chip package interaction on a 3D interposer package. A Design Of Experiments (DOE) was set up and parameters as epoxy mold compound (EMC) material properties, EMC thickness and die thickness were considered to study their effect on stress and package deformation. The results indicate that using a polymer that combines optimized mechanical properties with specific geometric dimensions makes it possible to reduce the package warpage and consequently the stress in the die. For this study, a multi-level sub modeling technique is used to access the stress distribution in the very small features in the packages, such as Cu μbumps. The stress analysis showed that by increasing the die thickness, the stress induced around μbumps increases. The results also showed that the EMC thickness has less impact on stress around μbumps than the die thickness.