Preparation and characterization of copper patterns on polyethylenimine-modified flexible substrates

We report a simple and low-cost method to fabricate copper circuit patterns on flexible polymeric substrates. This method relies on crosslinked branched polyethylenimine (PEI) films that incorporate palladium (Pd) catalysts, which are employed as adhesive interlayers for the fabrication of copper circuit patterns on polymeric substrates. Patterned Pd catalysts are immobilized on the polymeric substrates and subsequently initiate the selective deposition of copper in an electroless plating solution. We demonstrated the fabrication of patterned copper films on a variety of flexible polymers with minimum feature sizes of 200 μm. The films were characterized by ATR FT-IR, contact angle, XPS, XRD, TEM, SEM, EDX, and AFM. The adhesion between the flexible polymeric substrate and the copper film was also investigated. Our results indicate that this novel and facile fabrication method possesses great potential for applications in the electronics industry.