Engineering Model for Interfacial Stresses of a Heated Bimaterial Structure with Bond Material Used in Electronic Packages

Abstract

A model is proposed for the shearing and peeling stresses occurring at the interface of two thin bonded objects as a function of the effect of bond materials at the interface. The existing uniform temperature model proposed by Suhir is upgraded to account for different temperatures of the layers by incorporating a temperature ratio parameter and eventually a correction factor to Suhir's model. Then the model is further upgraded to account for the linear temperature gradients in the layers by incorporating two temperature drop ratios and eventually a second correction factor. This upgraded model can be considered as a generalized one for predicting temperature conditions which may occur in the bonded materials. A simpler method of solution is used to develop this model which does not involve solving integro-differential equations as found in the Suhir's method. The results are presented for the case of die and die attach as commonly found in electronic packaging and are compared to the case where a bond is absent. The results are also compared with those obtained by Finite Element Method (FEM) analysis.