Meso-scale crystal plasticity modeling of sintered silver nanoparticles in typical interconnected structures

As a widely used die-attach material for interconnected structures, sintered silver nanoparticles (AgNPs) exhibit high electrical conductivity and excellent thermal conductivity properties. This paper develops a framework of crystal plasticity (CP) finite element method from the dislocation slip mechanism and applies it to interconnected structure of sintered AgNP materials, based on which the thermal stress simulation under temperature cycling is completed. Firstly, a polycrystalline model for sintered AgNP with the required meso-scale structure is established using Abaqus software. Further, the macroscopic stress-strain behavior for sintered AgNP is accurately described by defining the CP constitutive parameters, which are directly influenced by the crystal orientations and slip systems. By the comparison of the simulation results and the experimental data, the validity and reasonableness of the proposed model are verified. Finally, a typical interconnect structure in power modules with the sintered AgNP material between the SiC chip and the metallization layer is established. By applying the temperature cycling to the entire interconnected structure, the temperature and stress distribution characteristics of the sintered AgNP layer are analyzed. The results show that the distributions of temperature and stress differ between the different grains due to differences in grain orientation and slip system orientation. Notably, significant stress concentrations are found in the area around the pores, indicating that cracks are likely to develop along the pores and expand further, leading to fracture of the material.