Interfacial stress due to thermal mismatch in layered structure has been considered as one of the major causes of mechanical failure in electronic packaging. The mismatch of the coefficient thermal expansion (CTE) of the materials in multi_layer structure may induce serious stress concentrations to the electronic composites such as interfacial delamination and die cracking. Therefore, the studies and evaluation of interfacial stress in electronic packaging become significantly important for failure prediction and design of the electronic devices.