Numerical study on the influence of material models for tin-based solder alloys on reliability statements

This paper presents a comparison of three different material models, which are currently used to describe creep behaviour of solder alloys in thermo-mechanical use cases. The first model is the commonly utilized Garofalo approach. This approach is based on a hyperbolic-sine equation to describe the secondary (stationary) creep rates dependent on the mechanical stress in combination with the Arrhenius equation to consider temperature dependencies. The other two material models cover the primary and the secondary creep stage. Here, unified viscoplastic constitutive models initially proposed by Anand and Chaboche et al. are introduced. In the presented FEM study result comparison has been done for the accumulated solder joint strains of a SMT component exposed to thermal cycling. Subsequently, the influence on creep strain progression and service life time estimation has been investigated.