UV direct-writing of metals on polyimide substrates

Copper micro-patterns have been fabricated on polyimide substrates without the use of evaporation techniques or photoresist materials. A novel easy light-directed metal patterning method has been achieved by using a photoreactive polymer reducing agent, methoxy poly(ethylene glycol) (MPEG) as a thin film coating. The interaction of UV light and MPEG in ethanol film enables the photoreduction of mobile silver ions previously incorporated within the surface-modified polyimide substrates. The silver nanoparticle patterns thus formed serve as a active catalytic seed layer for subsequent electroless copper plating. Narrow copper tracks with low resistivity close to that of bulk copper have been achieved.