Feasibility Evaluation of Creep Model for Failure Assessment of Solder Joint Reliability of Wafer-Level Packaging

Abstract

Among the thermomechanical creep models developed to predict the solder response to progressive inelastic deformation, the Anand model is the most common. However, recent studies have had markedly different formulations of the nine parameters in this model used to describe the stress-strain curve that occurs at nonlinear, temperature-dependent low strain levels under field conditions. Furthermore, this model lacks proper technical specifications compared to the hyperbolic sine model. This has led to the development of multiple user-defined creep models with customized codes that are incompatible with many commercial finite-element tools. Therefore, modifying the current Anand model to improve the reliability of its electronic packages has become an essential task. In this paper, a new creep model was developed based on the assumptions that an instantaneous steady-state creep form eliminates the evolution term, resulting in a creep equation with four parameters. The proposed model had a fundamental statement similar to that of the well-known hyperbolic sine model. The workability of the new model was demonstrated through a simulated solder response that tested the strain rate effect and different thermal cyclic loading profiles. This model greatly broadens the applicability of the hyperbolic model. Furthermore, the modified Anand model has better agreement than the Anand model with the experimental results for different types of electronic packages.