Scalable Synthesis of Monodispersed Branched Submicron Silver Particles as the Printed Electrically Conductive Adhesives Fillers

摘要

Electrically conductive adhesives (ECAs) are an important interconnecting material to electronic packaging industry due to the low processing temperature, fine pitch capability, simple process and mechanical flexibility compared with conventional solder and wiring technologies. Silver micro/nano-particles are widely used as conductive filler owing to their low electrical resistivity, chemical stability and various shapes and morphologies. In this study, we introduce a facile synthetic method of monodispersed branched submicron silver particles which is about 500 nm in size, by reducing the silver salts with N_2H_4·H_2O in an aqueous solution at room temperature. By tuning the reaction condition, a series of submicron silver particles with acute branches were obtained, and the feature size of each branch is smaller than 20 nm. The highly branched nanoparticles rendered them with a low sintering temperature and a low threshold to enable percolation, which can contribute to a significant increase in electrical conductivity of the ECAs. The ECAs based on these branched submicron silver particles demonstrate low bulk resistivity, which is approximately 1 ×10~(-4) Ω·cm. On account of the simple, cost-effective, scalable and eco-friendly liquid phase synthetic method, this technology may find potential applications in microsystems packaging and printed electronics.