In situ monitoring of flash-light sintering of copper nanoparticle ink for printed electronics

In this work, a flash-light sintering process for Cu nanoinks was studied. In order to precisely monitor the milliseconds flash-light sintering process, a real-time Wheatstone bridge electrical circuit and a high-rate data acquisition system were used. The effects of several flash-light irradiation conditions (irradiation energy, pulse number, on-time, and off-time) and the effects of the amount of poly(N-vinylpyrrolidone) in the Cu nanoink on the flash-light sintering process were investigated. The microstructures of the sintered Cu films were analyzed by scanning electron microscopy. To investigate the oxidation or reduction of the oxide-covered copper nanoparticles, a crystal phase analysis using x-ray diffraction was performed. In addition, the sheet resistance of Cu film was measured using a four-point probe method. From this study, it was found that the flash-light sintered Cu nanoink films have a conductivity of 72 Omega m/sq without any damage to the polyimide substrate. Similar nanoinks are expected to be widely used in printed and flexible electronics products in the near future.This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education, Science, and Technology (2012-0002843). Also, this work was partially supported by the Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (2012029029)