Experiments, constitutive modeling, and simulations on the creep behavior of the AgSn transient liquid phase metallic bonds

The transient liquid phase (TLP) bonding using the silver -tin system has been considered as one promising joining technique in power electronics due to their excellent thermal and electrical conductivity characteristics. In literature, there is a lack of published creep studies and creep constitutive models for the silver -tin (AgSn) transient liquid phase bonds. Therefore, this paper aims to present a comprehensive analysis of the inelastic creep behavior of multilayer silver -tin transient liquid phase (AgSn-TLP) foils by employing experiments, various constitutive models, and finite element simulations. A well-defined optimized bonding process is utilized to manufacture the AgSn-TLP test samples. Subsequently, creep tests are conducted at different loading temperatures and stress levels to generate creep data in the form of strain vs. time. The constitutive modeling parameters including Anand viscoplasticity, hyperbolic sine, and power laws, are accordingly determined through robust nonlinear least squares regressions. The resulting constitutive models exhibit a high degree of agreement with the measured data. Furthermore, finite element simulations are performed to assess the thermomechanical response of the AgSn-TLP bonds in comparison to other commonly used die attach materials. Overall, the silver -tin TLP bonds demonstrate superior resistance to the accumulation of inelastic strains, suggesting their potential for efficient performance in high -temperature engineering applications.