Effective elastic modulus of underfill material for flip-chip applications

In this paper, a micromechanics model based on the Mori-Tanaka method was developed to estimate the elastic modulus of underfill materials. An explicit expression of the underfill modulus was derived as a function of filler content and the properties of the matrix and the fillers. Predictions of the modulus from this theory were compared with experimentally measured values. Excellent agreement was observed.