Mechanical response of a low-temperature sintered body consisting of submicron gold particles

Sintered materials formed by sub-micron powder have been attracting attention as next generation functional materials. Since the surface energy of sub-micron particles is high, the sintering temperature is relatively low. Once a sub-micron powder is sintered, its structure is stable in the used temperature range. Therefore, sintered body of sub-micron particles are expected to be alternatives to current interconnect materials that have reached the limits of miniaturization. However, the mechanisms of deformation and fracture in sintered body formed from sub-micron particles are unclear yet. Specially, low temperature sintered body consisting of clusters of sub-micron particles provide several interesting mechanical properties. In this study, mechanical response of low temperature sintered body was examined. The gold powder and solvent were mixed into a paste and that was then sintered. Tensile strength and elongation of the sintered body were evaluated experimentally. Because microstructure of sintered body affects several mechanical properties, cluster structure was simulated using DLA (diffusion-limited aggregation) model and tensile properties of cluster structure were extracted from finite element analysis. Comparing with experimental results, the validity of cluster model simulation was examined. Low temperature sintered body has lower tensile strength and elastic modulus because of network of clusters. Cluster structure depends on the porosity and the sintering temperature. Simulated elastic stiffness depends cluster structure and its value is lower than bulk. The fracture behavior of particles in clusters connects macroscopic tensile strength and elongation of sintered body. It agrees with the SEM observation of the fracture surface. Cluster of particles characterizes the macroscopic mechanical properties of sintered body.