Fabrication of ITO conductive tracks on flexible substrate by UV roll nano imprinting

The increasing demands of flexible electronics in the field of flexible display, wearable computer, radio frequency identification and so on make the establishment of patterning technology of conductive tracks on large area flexible substrate with low cost a priority. In conventional flexible electronics fabrication processes, the conductive tracks are formed by lift-off or etching the deposited metallic layer using a barrier formed by photolithography or ink printing. In this study, a method is proposed to form conductive tracks on flexible substrate using UV roll nano imprinting, which is inexpensive and scalable down to sub micrometers. To examine the feasibility of the proposed method, an indium tin oxide (ITO) conductive tracks with widths of 2 ~ 20 um were formed using a UV roll nano imprinting system. A photopolymer pattern was imprinted on an ITO coated polymer film using a UV roll nano imprinting system, which was composed of a roll stamp, a material dispensing unit, a pair of flattening rollers, a contact roller, and a releasing roller. The roll stamp was fabricated by wrapping a thin metal stamp on a roll base, where the thin metal stamp was fabricated by an electroforming process. The ITO conductive tracks were patterned by the wet-etching process using the photopolymer barrier, obtained by UV roll nano imprinting process. Finally, the geometrical properties and electrical conductivity of fabricated ITO patterns were measured and analyzed.