Structural optimization of fine pitch, large die flip chip package

Abstract

In this paper we focus on the structural optimization of fine pitch, large die flip chip package by thermo mechanical analysis. At first the type of buildup substrate design that has to be used for this package is selected by conducting a comparative study of effect of four core substrate layer (2-4-2) and a two core substrate layer (2-2-2) on the overall stress distribution of the package. Second, an optimization study of package dimensions (the heat spreader dimensions, die chamber angles, structural adhesive thickness and bump size) is conducted with emphasis on the shear stress occurring at the die corner and warpage of the overall structure