An Analytical Model for Permeability of Underfill Flow in Flip-Chip Packaging With Consideration of the Actual Specific Surface and Tortuosity

Abstract

Permeability is an important concept in understanding and modeling the flow or dynamic behavior of fluids in a porous medium (e.g., flip chip in electronics packaging). There are two factors (specific surface and tortuosity) that affect the permeability of a porous medium, but they are ignored by analytical models for permeability in the literature. In this paper, we present an analytical model for permeability of the underfill porous medium in flip-chip packaging by consideration of the actual specific surface and tortuosity. The proposed model and other models without consideration of the actual specific surface and tortuosity are compared with reference to a well-proven numerical model. The result of comparison has shown a significant improvement in accuracy with our model. This paper contributes not only to the underfill flip-chip package, but also to the field of porous mediums with regular arrangements of pores.