Thermo-elasto-plastic phase-field modelling of mechanical behaviours of sintered nano-silver with randomly distributed micro-pores

Abstract

Nano-silver paste is an emerging lead-free bonding material in power electronics, and has excellent mechanical properties, thermal conductivity and long-term reliability. However, it is extremely challenging to model the mechanical and failure behaviours of sintered nano-silver paste due to its random micro-porous structures and the coupled thermomechanical loading conditions. In this study, a novel computational framework was proposed to generate the random micro-porous structures and simulate their effects on mechanical properties and fracture behaviour based on the one-cut gaussian random field model and the thermo-elasto-plastic phase-field model. The elastic modulus, ultimate tensile strength and strain to failure are computed statistically, showing good agreement with the experimental results. Further, the framework was applied to model the fracture of sintered nano-silver paste under thermal cyclic conditions, demonstrating the formation of distinctive crack patterns and complex crack networks. The cracking behaviours observed in the experiments and simulations are remarkably similar to each other. The framework was implemented within Abaqus via a combination of subroutines and Python scripts, automating the process of model generation and subsequent computation. This study provides an efficient and reliable approach to simulate the mechanical and failure behaviours of sintered nano-silver paste with random micro-porous structures.