High-resolution conductive patterns fabricated by inkjet printing and spin coating on wettability-controlled surfaces

In this study, we develop a simple and low-cost surface wettability patterning based on soft lithography processes such as nano-imprint lithography (NIL) and micro-contact printing (μCP) to fabricate high-resolution conductive patterns using two different solution processes: inkjet printing and spin coating. An epoxy-based photoresist layer was imprinted by an elastomeric stamp during the NIL process to produce negative micro-structures in the epoxy-based photoresist layer. To form surface wettability contrast, a hydrophobic fluorocarbon film was transferred onto the top surface of the imprinted epoxy-based photoresist layer using μCP. The epoxy-based photoresist layer was UV-treated before the μCP process in order to increase surface wettability contrast; the hydrophilic imprinted patterns surrounded by hydrophobic surfaces were fabricated in the epoxy-based photoresist layer. After printing Ag ink on the imprinted epoxy-based photoresist layer, high-resolution printed line array and square spiral patterns with line width and gap distance of several micrometers can be fabricated with an aid of high surface wettability contrast. Even though well-defined high-resolution conductive patterns with electrical resistivity lower than 6 μΩ cm can be obtained regardless of the solution processes, inkjet printing seems more efficient from the viewpoint of the amount of ink used in each solution process. The surface wettability patterning suggested in this study is expected to be used in the fabrication of high-resolution conductive patterns in printed electronics.