Improving Resolution for Roll-to-Roll Printed Electronics

H. Zhang, W.J. Suszynski, A. Ramm, S. Lim
University of Minnesota, US

Keywords: gravure, printing, roll to roll, flexible, printed electronics

Summary:

Roll-to-roll printing methods, such as gravure and flexographic printing, have been successfully used to fabricate flexible electronic devices. The smallest feature size attainable by these traditional printing methods, however, is usually larger than 80 µm, which may not be small enough for some devices. In this research, established photolithography is used to create much smaller gravure cells directly onto a flexible silicon wafer, which is then wrapped onto a roll. The pattern was also chemically treated to achieve a wettability difference between the gravure cell and the land (surface). Such treatment improved the ink loading process (no doctor blade needed) and decreased ink residue on the land, which might otherwise cause short circuits. The printing process was explored using glycerol-water mixtures as test ink. A systematic study will be presented to illustrate the effect of ink properties, gravure pattern design, printing process and substrate on the resolution of printed patterns and ink transfer effectiveness. Results to-date showed that no residue ink on the land after ink loading and printed patterns of dots and lines with size down to 10 µm in lateral dimension. Real inks will be used to print functional electronic devices.