극단파 광소결법을 이용한 유연성기판 위의 은 나노 잉크 소결 공정의 실시간 모니터링

Abstract

In this work, the flash light sintering process of the Ag nano-ink was investigated. Ag nano-ink pattern was printed on flexible PET (polyethylene terephthalate) substrate using a gravure printing system. The printed pattern was sintered by applying flash light from a xenon lamp using a in-house flash light sintering system at room temperature and in ambient condition. In order to monitor a few milliseconds light sintering process, whitestone bridge electrical circuit was devised and the changes of the voltage difference of the Ag nano-ink were recorded using an oscilloscope during the sintering process. The changes of sheet resistance were monitored using the devised in-situ monitoring system for various light conditions (e.g. light energy, on-time and off-time duration and pulse numbers). Using the devised in-situ monitoring system, the flash light sintering mechanism was analyzed in step-wise processes in each light pulses (e.g. evaporation of organic binder followed by forming of neck-like junction and its growth, etc.). Finally, the optimal sintering conditions of Ag nano-pattern were found without any damage on PET substrate and interfacial delamination between the Ag film and PET substrate based on the in-situ monitoring result. It was found that the optimized flash light sintering process could make a lower sheet resistance of the Ag film (0.95 ohm/sq) than that of the thermally sintered Ag film (2.03 ohm/sq).