Synergistic surface modification of silver powder: Mechanisms for tapped density enhancement and low-temperature sintering

Silver powder, as a pivotal material in electronics and new energy applications, critically depends on its tapped density and sintering activity. This study systematically optimizes the physical properties and sintering performance of micron silver powder through a synergistic surface modification strategy integrating jet milling classification and high-speed shear shaping. Results demonstrate that the modified silver powder exhibits a 40–45 % enhancement in tapped density (5.91 g/cm 3 ), a 50–56 % increase in apparent density (4.01 g/cm 3 ), a narrowed particle size distribution span (reduced from 2.93 to 0.52), and significantly improved flowability (angle of repose: 28.97°). The conductive silver paste formulated with modified powder achieves optimized rheological properties, including a 41.8 % higher 17-s recovery rate (84.5 %) and a 79.08 % reduction in static viscosity. Sintering experiments revealed that the modified silver powder achieved a maximum reduction in sintering temperature of 100 °C, with a relative density exceeding 97.3 % at 650 °C, with grain boundary diffusion and defect density modulation identified as the core mechanisms for densification. This work elucidates the synergistic regulatory mechanisms of surface modification on the sintering behavior of silver powders, aligning with the principles of tapped density enhancement and low-temperature sintering.