A phase-field study on thermo-mechanical coupled damage evolution and failure mechanisms of sintered silver interconnections

Sintered silver paste has emerged as one of the most promising green packaging interconnection materials in electronic packaging due to its combination of low-temperature processing and high-temperature service capabilities. At the microscale, sintered silver exhibits random porous structures influenced by sintering processes, leading to various fracture issues under complex operating conditions, where the mechanical reliability is significantly influenced by thermo-mechanical loading during service. This study establishes a thermo-mechanical coupled phase-field model incorporating mixed tensile-shear failure modes to investigate the mechanical behavior and fracture evolution of random porous structures reconstructed from SEM images of sintered silver. The phase-field approach effectively captures crack initiation and propagation without explicit crack tracking by introducing a regularized description of discontinuities. Numerical predictions of elastic modulus and tensile strength show good agreement with experimental results under various loading conditions, including tensile, shear, and end- notched flexure (ENF) tests. Simulations of crack propagation under thermal and shear loading conditions reveal distinctive crack patterns and complex crack networks. The proposed approach provides an efficient and reliable method for simulating the mechanical behavior and failure mechanisms of sintered silver solder with random porous structures, offering valuable insights for improving electronic package reliability.