Geometric optimization and mechanical risk mmitigation in 2.5D flip-chip packages using parametric finite element analysis (FEA) simulations

This study is focused on geometric optimization of a 2.5D interposer based single die flip-chip package. Parametric analyses using the well-established global-local finite element method (FEM) technique have been conducted on the package at both the pre and post encapsulation (or underfill) stages. At the pre and post encapsulation phases, effects of geometric parameters which included variations in silicon die dimensions, interposer dimensions and substrate dimensions were analyzed to determine the corresponding mechanical risks associated during the die bonding and capping process. The geometric optimization at the macro-scale was focused on reducing die-underfill shear stresses and strains in the thermal interface material (TIM). At the local level, studies were geared towards understanding the impact of geometric variables on the solder inelastic strain and stresses within the back end of the line layers within the chip. The results presented from both these modeling analyses will provide configurations that reduce the overall mechanical risks in 2.5D packages and provide guidelines for geometric optimization of such packages.