Surface activation of polyimide with dielectric barrier discharge for electroless metal deposition

Electroless plating of non-conducting materials needs, prior to the metal d eposition itself, to make the sample surface catalytically active. The rout e involving the chemical reduction of a thin solid metal-organic coating ha s, for this purpose, a significant potential in reducing the number of step s which are required today in conventional wet chemical metallization proce sses. In this work, a novel activation process using a dielectric barrier d ischarge (DBD) is described for the first time. This process is based on th e plasma-induced chemical reduction at atmospheric pressure in air of palla dium acetate (PdAc) layers resulting in the formation of palladium (Pd) on non-active surfaces. Fast surface activation of polymers like polyimide (PI ) was found to occur in only a few seconds using a simple DBD device instea d of expensive excimer UV lamps or complicated laser systems. The DBD-induc ed Pd layers on PI exhibit high activity with regard to initiation of the e lectroless copper plating. Indeed, copper deposition starts immediately aft er dipping the activated PI samples in the electroless solution without any inhibition time. Homogeneous copper coatings on PI were achieved under opt imal plasma treatment conditions. The results are compared to those achieve d with excimer UV lamps and excimer UV lasers. (C) 2000 Elsevier Science S. A. All rights reserved.