Reactive Sintering of Copper Nanoparticles Using Intense Pulsed Light for Printed Electronics

Abstract

Most commercial copper nanoparticles are covered with an oxide shell and cannot be sintered into conducting lines/films by conventional thermal sin- tering. To address this issue, past efforts have utilized complex reduction schemes and sophisticated chambers to prevent oxidation, thereby rendering the process cost ineffective. To alleviate these problems, we demonstrate a reactive sintering process using intense pulsed light (IPL) in the present study. The IPL process successfully removed the oxide shells of copper nanoparticles, leaving conductive, pure copper film in a short period of time (2 ms) under ambient conditions. The in situ copper oxide reduction mecha- nism was studied using several different experiments and analyses. We observed instant copper oxide reduction and sintering through poly(N-vinyl- pyrrolidone) functionalization of copper nanoparticles, followed by IPL irra- diation. This phenomenon may be explained by oxide reduction either via an intermediate acid created by ultraviolet (UV) light irradiation or by hydroxyl (-OH) end groups, which act like long-chain alcohol reductants.