I. Introduction
During large-scale integrated circuits (ICs) in service, the mismatch of coefficient of thermal expansion (CTE) between components and boards generates thermally induced strains in solder joints by a power and environmental temperature change which leads to thermal fatigue failures. It is recognized as a major cause of failure in surface mounted electronic devices. Therefore, development of a prediction life method of solder connection is necessary for the quality assurance of ICs. The finite element analysis (FEA) method is extensively implemented to analyze the reliability of electronic packaging for ICs [1]–[3]. In the application of the FEA method, a more accurate constitutive model which is used to describe the stress strain relationship of solder is desired.