Low resistivity achieved through enhanced sintering activity in silver paste with submicron particles created through nanoparticle self-assembly

Silver powder’s size and dispersion affect the performance of conductive silver paste. Micron-sized silver powder has good dispersibility but poor sintering activity at low temperatures. In contrast, silver nano-powder sinters at low temperatures but tends to agglomerate. To address the aforementioned issues, this paper employs a chemical reduction method to prepare high-sintering-activity submicron spherical silver powder with a large number of nanoscale bumps on its surface. The study investigates the effects of various factors on the surface morphology and particle size distribution of the silver powder, including the amount of citric acid added, the speed of the reducing agent’s addition, the pH value, and the temperature of the reaction solutions. In addition, silver pastes with varying silver powder contents (60, 70, 80, and 85 wt. %) were prepared to test their resistivity. The results indicate that the lowest resistivity of 8.9 × 10−6 Ω cm was achieved when the silver powder content was 85 wt. % and the conductive silver paste was sintered at 250 °C for 30 min. Furthermore, the prepared conductive silver pastes maintained good resistivity even when sintered at low temperatures.