Copper electroless plating at selected areas on aluminum with pulsed Nd-YAG laser

Local deposition of copper on aluminum was attempted by the successive processes of anodizing, laser irradiation, and electroless plating. Aluminum specimens covered with anodic oxide films were immersed in Cu2+, Cu2+/H2PO2-, and diluted NaOH solutions, and irradiated with a pulsed yttrium aluminum garnet (YAG) laser. The time variation in the rest potential of the specimens was followed during laser irradiation by a potentiometer, and the change of the surface composition by laser irradiation was examined by X-ray photoelectron spectroscopy(XPS). After the laser irradiation, copper electroless plating was carried out in (Cu2+ Ni2+)H2PO2- solutions with or without Pb2+ or thiourea. The rest potential measurements and XPS analysis suggested that Cu particles nucleate at the film-removed area by laser irradiation in Cu2+ and Cu2+/H2PO2- solutions. A copper layer was obtained at the irradiated area by the subsequent electroless plating, and the copper nuclei acted as catalytic centers at the very initial stage in copper electroless plating. The effects of Pb2+ and thiourea concentration and the deposition temperature on the kinetics of copper deposition is also discussed. (C) 2000 The Electrochemical Society. S0013-4651(99)06-129-7. All rights reserved.