Facile Patterning Using Dry Film Photo-Resist for Flexible Electronics: Ag Nanowire Network and Carbon Nanotube Network
In this study, we explored the use of dry film photo-resist (DFR) in the patterning of Ag nanowire and carbon nanotube (CNT) networks for the first time. With a simple lamination process, the DFR was uniformly coated on the Ag nanowire and CNT networks on poly(ethylene terephthalate) (PET) substrates without a post-thermal baking process. Furthermore, a Na2CO3-based developer enabled the networks to be patterned without a loss of conductivity. Scanning electron microscope images revealed that the Ag nanowire and CNT network were successfully patterned with a pattern width up to ~30 μm. The patterned Ag nanowire networks were confirmed to follow the percolation theory, showing logarithmically linear increase in resistance as the pattern width decreased. The results indicated that there was no harmful effect on the Ag nanowire network during the patterning process. In addition, the mechanical reliability under bending fatigue was explored that revealed the pattern-size dependent bending fatigue behavior, where the Ag nanowire networks with the smaller pattern width showed the higher increase in resistance during bending fatigue. The simple patterning method using DFR is expected to lead the future patterning technology combined with the roll-to-roll process.