Photochemical functionalization of polymer surfaces for subsequent metallization

Plasma-treated polymers typically show changes of surface morphology as wel l as modifications in their chemical composition. Both effects are known to have an influence on deposition and adhesion of metal coatings, although t he exact mechanisms are not yet understood. Besides high-energy electrons a nd chemically active species, the generated UV radiation is one major compo nent of plasma surface modification. The energy of ultraviolet photons is s ufficiently high to induce bond scissions in polymeric materials, which res ult in subsequent chemical reactions. In this study, excimer radiation from lasers (e.g. KrF, 248 nm) or lamps (e .g. KrCl, 222 nm) was used for the formation of polar functional groups on the surface. The treatment was carried out at atmospheric pressure, mostly in air. The chemical and physical properties of the irradiated surface are different compared with untreated areas. The resulting functional groups al low for a spontaneous deposition of molecular thin films from aqueous solut ions. In particular, these can be complexes from noble metals. Noble metals catalyze deposition in electroless metallization baths. A process for sele ctive metal deposition on polymers has been developed based on this princip le. After deposition, the main issue is the adhesion that can be achieved in th e polymer-metal interface. II is determined by chemical or physical interac tion between the polymer surface and the adjacent layer, as well as by typo graphical features. (C) 1999 Elsevier Science S.A. All rights reserved.