Numerical investigation of ceramic package/ interposer interconnects using isotropic conductive adhesive

The aim of this study is to investigate the applicability of using an epoxy based isotropic conductive adhesive (ICA), to mount a silicon 3D system-on chip (SoC) in a ceramic 16 pad leadless chip carrier (LCC). We present and discuss thermo-mechanical FEA simulation results obtained by implementing the viscoelastic properties of the adhesive. A generalized Maxwell model using Prony series was considered in this study. We analyse the generated strain and stress in the ICA interconnect as a function of the adhesive geometry for two high and low operating temperatures. The goal is to define an optimal volume and geometry of the cured adhesive with respect to minimized stress at the interfaces between the pads and the adhesive. The target is to reduce the risk of crack initiation and propagation caused by thermal stress by careful design.