The edge-effect on roll-to-roll thermal embossing of micro channels

Roll-to-roll thermal embossing is a rising trend for large area processing of micro structures. However, pile-ups are formed when micro channel patterns are fed perpendicularly to the feeding direction of the embossing. Thus, there is a need to study the pile-up formation in order to reduce it for quality embossed patterns. In this work, polymethyl methacrylate and polypropylene films are used as the polymer substrates and the pile-up formation at various embossing temperature points or under various embossing pressures in the roll-to-roll embossing process is investigated. It is discovered that for polypropylene, there is a transition temperature range. Before this range, the lead pile-up is higher than the lag pile-up, while after this temperature range, the lag pile-up is higher than the lead pile-up. For polymethyl methacrylate, the lead pile-up is higher than the lag pile-up. By using a high embossing temperature and a high embossing pressure, it is able to reduce the pile-up formation and achieve good embossed patterns.