Electroless plating of palladium and copper on polypyrrole films

A novel process for the metallization of polypyrrole (PPY) film surface thr ough consecutive electroless plating of palladium and copper in the complet e absence of the SnCl2 sensitization step was demonstrated. X-ray photoelec tron spectroscopy (XPS) technique was used to characterize the polymer surf ace at each stage of the metallization process. It was found that only the fully reduced PPY film could reduce palladium ions to palladium metal (Pd(0 )) in substantial amounts from either the Pd(NO3)(2) or PdCl2 acid solution . The palladium metal was necessary for catalyzing the subsequent electrole ss plating of copper. The reduction of Pd(II) ions in acid solution to Pd(0 ) on the film surface was accompanied by a simultaneous increase in intrins ic oxidation state and doping level of the film. The copper plating process after the palladium uptake step was highly dependent on the [Pd]/[N] ratio on the film. Through XPS and Auger photoeletron spectroscopy measurements, it was postulated that during the electroless copper plating process, the Cu(II) ions were first reduced to Cu(I) on the PPY film surface before comp lete reduction to copper metal. (C) 2001 Elsevier Science B.V. All rights r eserved.