Microstructure and mechanical properties of sintered Ag particles with flake and spherical shape from nano to micro size

This work firstly evaluated the microscale mechanical properties of sintered Ag, consisting of various Ag particles of a flake shape and spherical shape from nano to micro size. Microscale pillar specimens were fabricated by a focused ion beam process and the mechanical properties of the sintered Ag, were measured by micro-compression testing using a nano-indentation system. The microstructure of sintered Ag is dependent upon the size and the shape of the utilized Ag particles, as this significantly influences its fracture behavior and mechanical properties. Mechanical properties not only depend on the porosity of the sintered Ag, but also on the degree of necking growth of the Ag particles. To explore this further, the shear strength of Ag sinter joint using different sizes and shapes of Ag particles was also evaluated. This revealed that sintered Ag flake particles possess a much greater bonding strength above 30 MPa than do sintered Ag spherical shape particles from nano to micro sizes. TEM observation revealed that many nanoparticles with a size less than 10 nm were formed in the sintered Ag flake structure due to its high grain boundary density and dislocation density, which increased its grain bonding quality. Keywords: Ag sinter joint, Nanoparticles, Micro-compression test, Mechanical properties, Die attach modules