Investigating Sintering Mechanism of 100 nm Ag Nanoparticles via In-situ SEM Observation and Phase Field Simulation

Driven by the rapid development of high-power electronics, Ag pressureless sintering technology has become a promising die-attach solution. For an in-depth understanding of the pressureless-sintering mechanism, this study employed in-situ scanning electron microscopy to observe the sintering process of Ag nanoparticles with a diameter of 100 nm at 200°C and entirely recorded the formation of sintering necks and changes in the dihedral angle between particles. The Ag nanoparticles formed a stable sintering neck of approximately 49 nm and a dihedral angle of 100° after 60 minutes of sintering. According to the empirical formula, we estimated the surface diffusivity of 100 nm Ag nanoparticles at 200°C as 3.99×10^-6 nm²/s, nearly two orders of magnitude lower than the 40 nm diameter Ag nanoparticles provided in previous literature. Furthermore, new phase-field parameters in the sintering simulation were suggested based on the relationship between the dihedral angle and surface energy to prepare for the microstructure evolution of the multi-nanoparticle sintering process.