전자잉크의 소결시에 물리적 물성변화 연구

Abstract

최근 태양전지, RFID(Radio frequency identification), 유연 디스플레이 등의 제조에 있어서 기존의 반도체 공정의 대체 공정으로 R2R(Roll to Roll), 잉크젯 프린팅 인쇄 공정이 각광 받고 있다. 기존의 반도체 공정과 비교해 보면, 전도성잉크를 사용하는 프린팅 공정에서 발생되는 폐기물의 양이 기존 반도체 공정보다 적다. 프린팅 공정에서 사용되는 잉크는 전기 전도를 위해 금속 입자를 함유하게 된다. 전도성잉크에서는 금속입자 사이의 반 데르 발스(Van der Waals) 힘을 방지하기 위해서 금속입자를 계면활성제가 둘러싸고 있다. 금속 입자의 표면을 감싸고 있는 계면활성제는 금속 입자간의 전기 전도를 방해하는 작용을 하게 된다. 이는 인쇄된 회로에서 입력 신호에 빠르게 응답하지 않는 RC-지연(delay)를 발생시키는 원인이 된다. 따라서, 전기 전도도 향상을 위해 열처리와 같은 소결 공정이 필요하게 된다. 하지만 열소결 공정 수행시에 소결온도, 소결시간에 따른 전도성잉크의 전도도 등의 특성이 명확하게 규정되어 있지 않아 이에 대한 연구가 필요하다. 그리고, 새로운 열소결방법으로서 레이저 열소결법에 대한 연구가 진행 중이지만, 자료가 미비한 상태이다. 본 연구에서는 전도성 잉크의 파장에 따른 광학물성치를 측정하여 반사율과 흡수율 값을 구할 수 있었다. 그리고 전도성 잉크의 소결을 각각 가열로 열소결법과 레이저 열소결법을 이용하여 수행하였다. 반사율은 소결이 진행될수록 증가하는 경향을 보인다는 결과를 얻었고 잉크의 비저항은 입자 연결도와 관련이 있다는 결과를 얻었다.| Recently the ink-jet printing, R2R, and printing processes are spotlighted in flexible electronics field due to the reduction of production cost instead of the semiconductor fabrication processes. Compared with the expensive traditional semiconductor processes, the printing process with the silver nanoparticle ink has merits to minimize the toxic waste and the manufacturing time. The conducting metal particles in the ink are surrounded by the surfactant to prevent Van der Waals force during the printing process. The lack of the direct connection in the ink results in the significant resistance increase. This causes the large RC-delay in the printed circuit to respond slowly to the input signal. The conductivity of the printed silver nanoparticle ink is needed to be improved for the high performance of the printed device. The curing process required to enhance the electrical conductivity of the printed the silver nanoparticle ink by coagulating the silver nanoparticles. However the conductivity of conductive ink by temperature and time of the curing method isn't defined a criterion. So this study is needed. And the study of the laser curing method being carried out as a new curing method. But the data is lacking. In this study, the nano-ink including silver nanoparticles is conducted by furnace curing method and laser curing method. And the reflectance and absorptivity of the nano-ink including silver nanoparticles were calculated from the experimentally obtained refractive indices. Consequently, the specific resistance of nano-ink is related to packing density. As the curing process proceeds, reflectivity is increase.; Recently the ink-jet printing, R2R, and printing processes are spotlighted in flexible electronics field due to the reduction of production cost instead of the semiconductor fabrication processes. Compared with the expensive traditional semiconductor processes, the printing process with the silver nanoparticle ink has merits to minimize the toxic waste and the manufacturing time. The conducting metal particles in the ink are surrounded by the surfactant to prevent Van der Waals force during the printing process. The lack of the direct connection in the ink results in the significant resistance increase. This causes the large RC-delay in the printed circuit to respond slowly to the input signal. The conductivity of the printed silver nanoparticle ink is needed to be improved for the high performance of the printed device. The curing process required to enhance the electrical conductivity of the printed the silver nanoparticle ink by coagulating the silver nanoparticles. However the conductivity of conductive ink by temperature and time of the curing method isn't defined a criterion. So this study is needed. And the study of the laser curing method being carried out as a new curing method. But the data is lacking. In this study, the nano-ink including silver nanoparticles is conducted by furnace curing method and laser curing method. And the reflectance and absorptivity of the nano-ink including silver nanoparticles were calculated from the experimentally obtained refractive indices. Consequently, the specific resistance of nano-ink is related to packing density. As the curing process proceeds, reflectivity is increase.