In this paper, a sintering process for nickel nanoparticles using flash light irradiation was investigated for multilayer ceramic capacitors, magnetic devices and printed electronics. The existence of a small amount of 10 nmsize nanoparticles in the ink significantly improved the flash light absorption and induced the melting and sintering of the nanoparticles. Due to this phenomenon, uniform diameter nickel nanoparticles (50 nm) could not be sintered, while the nickel nanoparticles with varying diameters (5-500 nm) were sintered by flash light irradiation. In order to acquire high electrical conductivity in the sintered nickel nanoparticles, several flash light sintering parameters such as light energy and pulsed light patterns were optimized. Also, the nickel nano-ink was optimized by changing the weight fractions of organic binder in the ink. (C) 2013 Elsevier B.V. All rights reserved.