Process Development of Large Area R2R Printing and Sintering of Conductive Patterns by Inkjet and Infra-Red Technologies Tailored for Printed Electronics

Abstract

The technological advancement in the field of printed electronics over roll-to-roll (R2R) platform has become very attractive, because of the several advantages such as mass production, large area application, cost-saving and high-speed capabilities. The inkjet technology, on the other hand, among other printing technologies promotes individualization and contact-less deposition process qualities. In this article, the authors demonstrate the state of the art R2R setup for printing silver (Ag) conductive patterns on PEN substrate using inkjet and infra-red technologies. The deposition of the conductive patterns was accomplished using a nanoparticle-based Ag ink and industrial printheads from Fujifilm Dimatix. The novelty of the research work is realization of a print setup, consisting of an industry relevant flexible printhead assembly and drop evaluation station, which are mounted over a R2R printing system. The entire setup allows the user to first evaluate the ejection of the droplets and then stabilize the print parameters without involving the web substrate, followed by re-positioning of the inkjet assembly back to the R2R printing system. The capability of the print setup is exhibited by varying the printing resolution for the defined digital patterns. In addition, the post-treatment of the conductive patterns was tailored with the implementation of an infra-red based sintering module from Heraeus Noblelight GmbH. The power density of the filaments from the sintering module was varied to achieve the maximum conductivity and to ensure no physical damage to the patterns and substrate. The results indicate that such a print setup is very flexible and can offer several benefits to the printing process of conductive patterns, e.g., obtaining line width below 80 μm and sheet resistance of about 0.5 Ω/□, with the advantage of sintering the patterns within 20 s.