Finite element analysis of lidded flip-chip packages: A study on the impact of thermal interface material compressibility and stress-free conditions on modeling predictions

摘要

In this paper, we present the effects of assumptions made about the constitutive behavior of a cured, silicone gel type thermal interface material (TIM) and the package stress-free conditions on FEA modeling predictions. The focus will be on the deformations (or warpage) predicted by the models for lidded flip-chip packages. It is critical for such warpage predictions to be close to experimental measurements for accurate projection of mechanical stresses and strains in a package. Digital Image Correlation (DIC) warpage measurements on flip-chip modules are compared against the predicted values and the impact of above-mentioned assumptions will be discussed. It will be shown that the TIM mechanical and thereby, thermal degradation is a strong function of the TIM compressibility and stress-free condition assumptions. Bounds of non-linear elastic modeling technique for the TIM and guidelines for conducting numerical analysis for lidded flip-chip packages will be provided.