Device fabrication in printed electronics with roll-to-roll slot die coating and laser direct writing process

Abstract

Printed Electronics are one of the important technologies in electronics and new markets such as OLED display, organic photovoltaics, and batteries. In this study, to overcome the problems and disadvantages of the current printing process proposed a new fusion process. The proposed study is applied to a printed electronics device fabrication to confirm the possibility of the application. My research propose a new approach to fuse roll-to-roll slot-die coating and laser direct writing process. The purpose of this research is to expand the 1-dimensional pattern process of slot-die coating to the 2-dimensional process and to use laser direct writing with the advantages of digital process, which is featured by no masks, non-contact, and low-cost. An Roll-to-roll slot die coating was studied to be optimized with a film speed, an ink flow rate, and a NIR lamp power. Maximum film speed of 2.4m/min is possible and an Ag film having a sheet resistance of 200mOhm/sq was confirmed. LDW process onto Roll-to-roll printing processed flexible metal film was applied successfully to make 2-D patterns. The LDW process was studied to be optimized with a scan speed and a laser power. LDW process with 5um, 7um, and 20um spot size was performed and the minimum linewidth was characterized. Piezo-resistive type strain gauge sensor element was fabricated by using this technology. A strain gage with Ag film showed a similar excellent properties with the commercial one. In additions, A highly reflective Ag film was fabricated by roll-to-roll slot die coating in order to produce the low concentration reflective solar module. The 20mm $\times$ 20mm Si cell with the solar cell efficiency of 4.9% were used and confirmed 2.14 times of the output power with 2.22x CPC PV module. In this study, various applications by utilizing slot die coating and LDW process were not proceeded. A variety of application devices can be possibly made with the advantage of a roll-to-roll printing process and LDW process to simplify the pattern forming process.