UV direct-writing of metals on polyimide

Abstract

Conductive micro-patterned copper tracks were fabricated by UV direct-writing of a nanoparticle silver seed layer followed by selective electroless copper deposition. Silver ions were first incorporated into a hydrolyzed polyimide surface layer by wet chemical treatment. A photoreactive polymer coating, methoxy poly(ethylene glycol) (MPEG) was coated on top of the substrate prior to UV irradiation. Electrons released through the interaction between the MPEG molecules and UV photons allowed the reduction of the silver ions across the MPEG/doped polyimide interface. The resultant silver seed layer has a cluster morphology which is suitable for the initiation of electroless plating. Initial results showed that the deposited copper tracks were in good agreement with the track width on the photomask and laser direct-writing can also fabricate smaller line width metal tracks with good accuracy. The facile fabrication presented here can be carried out in air, at atmospheric pressure, and on contoured surfaces.

Laser-induced copper deposition from aqueous and aqueous–organic solutions: state of the art and prospects of research

“…A considerable advantage compared to other methods using laser radiation is that it can be used to fabricate highly conducting metal structures. 7,8 The LCLD technique can be employed to deposit the following metals onto the surface of various dielectrics: copper, silver, 9 palladium, 10 platinum, 11 nickel, 12 gold, 13 chromium and tungsten. 14 The copper deposition is of most practical interest because copper is widely used as a conducting material in microelectronics, as well as due to the catalytic activity of copper-based nanoparticles.…”