microparticles ink via flash light sintering for printed electronics

In this study, the size effect of copper particles on the flash light sintering of copper (Cu) ink was investigated using Cu nanoparticles (20-50 nm diameter) and microparticles (2 mu m diameter). Also, the mixed Cu nano-/micro-inks were fabricated, and the synergetic effects between the Cu nano-ink and micro-ink on flash light sintering were assessed. The ratio of nanoparticles to microparticles in Cu ink and the several flash light irradiation conditions (irradiation energy density, pulse number, on-time, and off-time) were optimized to obtain high conductivity of Cu films. In order to precisely monitor the milliseconds-long flash light sintering process, in situ monitoring of electrical resistance and temperature changes of Cu films was conducted during the flash light irradiation using a real-time Wheatstone bridge electrical circuit, thermocouple-based circuit, and a high-rate data acquisition system. Also, several microscopic and spectroscopic characterization techniques such as scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the flash light sintered Cu nano-/micro-films. In addition, the sheet resistance of Cu film was measured using a four-point probe method. This work revealed that the optimal ratio of nanoparticles to microparticles is 50:50 wt%, and the optimally fabricated and flash light sintered Cu nano-/micro-ink films have the lowest resistivity (80 mu Omega cm) among nanoink, micro-ink, or nano-micro mixed films.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education 2012R1A6A1029029). This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. 2013M2A2A9043280). We would like to acknowledge the financial support from the R&D Convergence Program of MSIP (Ministry of Science, ICT and Future Planning) and ISTK (Korea Research Council for Industrial Science and Technology) of Republic of Korea (Grant B551179-13-02-05). This research was also supported by a grant from the Technology Development Program for Strategic Core Materials funded by the Ministry of Trade, Industry & Energy, Republic of Korea (Project No. 10047758)