Electrical current enhanced sintering without Joule heating for Cu nanoparticles at room temperature

Sintering copper nanoparticles can be achieved with low electrical current density at 25 °C in ambient. The nanoparticles are printed in a V-groove etch on a silicon wafer and are stressed using an electrical current. Voids in the current-enhanced sintered Cu are considerably less than that without current. Sintering at room temperature avoids interference from Joule heating. Besides surface diffusion along the particles and atomic motion driven by current, the current crowding effect at the necking region is critical. The mechanism of electric current on densification and electrical properties of Cu NPs were investigated. Herein, two mathematical models were proposed to elucidate the sintering mechanism. The results prove that the kinetics of neck growth affects the carrier concentration and total atomic diffusion fluxes in the necking region when the current flows through two nanoparticles. The proposed mathematic models implement traditional sintering mechanisms, providing a more precise prediction for the enhanced sintering of the particles with an electrical current.