Water vapor-assisted sintering of silver nanoparticle inks for printed electronics

Abstract

In printed electronics, conductive traces are often produced by printing inks of silver nanoparticles dispersed in solvents. A sintering process is usually needed to make the printed inks conductive by removing the organic dispersants and allowing metal-to-metal contacts among nanoparticles for atomic diffusion and neck formation. It has been challenging to sinter silver nanoparticle inks in a thermal oven at a temperature < 150 °C to avoid thermal damage to the plastic substrate while achieving desired conductivity. This work presents a simple, yet effective way to sinter a silver nanoparticle ink below 120 °C (even at 80 °C) by exposing the printed ink to water vapor in the oven. The results consistently show a significant reduction in line resistivity for the samples sintered in a moist oven compared to those sintered in a dry oven. For example, the measured resistivity can become 9.32 μΩ cm (5.90 times that of bulk silver) when a silver nanoparticle ink is sintered with water vapor at 120 °C for 30 min. Hence, solvent vapor-assisted sintering of metal nanoparticle inks can become an enabling approach to broadening the product range of printed electronics.