S. Deshmukh, S. Burbine, S. Banerjee, E. Keaney, E. Hajisaeid, A. Akyurtlu, C. Peters, M. Herndon, D. Rockosi, C. Lepont, C. Barry, J. Mead
University of Massachusetts Lowell,
Keywords: flexible printed electronics
Summary:Flexographic printing process is widely used for printed electronics due to its capability of continuous printing, ease of flexible plate making, design change, high printing speed, etc. Flexographic printing in combination with roll-to-roll (R2R) process has the benefits of high production rates with in-line oven curing can produce rolls of finished material in an efficient and cost-effective manner. This research will present a continuous R2R flexographic printing process on a highly filled flexible dielectric thermoplastic substrate. This substrate is manufactured in-house by melt mixing of a thermoplastic polymer, Low-density polyethylene (LDPE) with a ferroelectric filler, Barium Strontium titanate (BST). The role of ferroelectric filler is to enhance the electrical properties of the substrate, such as dielectric and tunability, which are essential for printed electronics. A suitable conductive ink with a minimum silver content of 50% is used for this printing. The ink selection depends on the various processing parameters like substrate type, printing speed, print design width, ink viscosity, curing temperature, etc. Considering the effects of parameters on substrate, ink and printed design, the processing parameters have been optimized. The criticalities with flexographic printing like appropriate ink and substrate selection based on print design features, application temperature, speed of printing line, curing conditions and optimization of the overall process are discussed critically.