Micro-LED 전사 공정 설계를 위한 실리콘 점착층 전사필름과 UV 경화성 점착제의 점착특성 평가

Abstract

This research aimed to evaluate the adhesion properties of transfer films and target substrate materials and design an appropriate transfer process for flexible and transparent micro-LED displays. The adhesion between transfer films and the micro-LEDs should be smaller than the adhesion between the target substrate and the micro-LEDs for successful transfer process. Colorless Polyimide(CPI) film coated with a UV-curable adhesive was used as the target substrate. Various transfer films with a silicone-based adhesive layer were used to transfer micro-LED arrays. Pull-off forces on the transfer films and the target substrate were measured using a micro-tribometer at different contact load and separation velocity to predict the transfer of micro-LED arrays from the transfer films to the target substrate. The results showed that the pull-off forces on the transfer films were increased with contact load and separation velocity. On the other hand, the pull-off forces on the target substrate increased and decreased with UV exposure time. Based on the adhesion test results and the transfer test, the transfer film (TF-C) was used and the target substrate was cured for 90 s for the highest transfer yield. As a result, the transfer yield was achieved to 99.82% for monochromatic micro-LED arrays and 96.78% for RGB micro-LED arrays. This work demonstrates the feasibility of fabricating flexible and transparent micro-LED displays by the transfer process.