Inkjet printing of palladium catalyst patterns on polyimide film for electroless copper plating

A convenient method has been developed that provides for applying patterned copper tracks on flexible polyimide film for electronic applications. The workflow comprises inkjet printing of an aqueous palladium(II) solution onto surface treated polyimide film, followed by reduction to metallic palladium and electroless copper plating. All processing steps involved require minimal infrastructure and result in metallic feature dimensions down to 100 μm using a desktop inkjet printer. Ink stability is documented by UV/vis, and copper line dimensions and electrical resistivity are examined as function of design dimensions and electroless plating time. The procedure was successfully applied for manufacturing interdigitated electrode films as used in active fiber composites.