A fine line/space fabrication process on flexible polyimide film using laser direct writing method by photothermal effect of silver nanoparticles

This article describes a fine line/space fabrication process on flexible polyimide film using laser direct writing method by photothermal effect of silver nanoparticles. Since the AgNPs have a strong optical absorption at 405 nm, a UV laser (405 nm, 60 mW) is used to trigger AgNPs to convert light into heat due to photothermal effect of nanoparticles. After UV laser beam irradiating on the AgNPs thin film, the AgNPs aggregate into larger conducting grains and improve the adhesion between AgNPs and the polyimide substrate at the same time. Then the desired AgNPs conductive lines (line width: 10 μm, line space: 20 μm) are formed after washing the unirradiated AgNPs. Copper plating is also used to increase the electrical conductivity of the laser direct patterning of AgNPs conductive lines. In this method, the conductive line patterns can be made by a low power consumption process (<; 60 mW) and with high energy transformation efficiency due to photothermal effect of nanoparticles.