Investigation of creep behaviors in three-dimensional porous sintered silver by FFT homogenization

Porous sintered silver is increasingly recognized as a key interconnection material for future high-temperature power device packaging due to its excellent thermal performance and mechanical properties. However, accurately predicting the creep behavior of porous sintered silver remains challenging. To address this, an enhanced FFT-based homogenization method was implemented to efficiently analyze the creep behavior of porous structures, accommodating different discretization methods. This approach incorporates a Representative Volume Element (RVE) model with porous microstructures using Gaussian random fields. Using a double power law creep constitutive model, this study aims to analyze the macroscopic and microscopic mechanical responses of porous sintered silver under different temperatures, strain rates, and loading conditions including stresses triaxiality and creep loading. The research findings reveal that the predictions from the Ramakrishnan-Arunachalam creep model closely match the FFT-based results, but as porosity and stress increase, the difference increases. Additionally, the presence of pores weakens the tensile properties of sintered silver, and this effect is more significant under high stress triaxiality conditions. Furthermore, the influence of pores on creep properties increases rapidly with increased applied stress before stabilizing at higher stress levels. These research results could provide some valuable insights for further understanding and controlling the creep behavior of porous sintered silver, which is crucial for optimizing its application in power electronic packaging.