Tin-free electroless metallization of glass substrates using different PACVD surface treatment processes

Plasma techniques are powerful surface modification tools. In this work, they are used to prepare glass surfaces before catalysis via a tin-free process and Ni electroless metallization. To bring this process into operation, an intermediate thin film of hydrogenated amorphous carbon (a-C:H) is deposited in a first approach by plasma polymerization of methane. Subsequently, this film is functionalized by N-2, or NH3, plasma treatment in the aim of chemisorbing the catalyst of metallization (Pd) directly onto the grafted nitrogenated groups. This chemisorption is performed by immersion in a mere acidic PdCl2, solution. A variant of this process consists in depositing a carbon nitride (CNx) thin film from a CH4/N-2, or CH4/NH3, gas mixture in the aim of grafting palladium onto the nitrogen atoms present at the surface of the film. A second approach involves the deposit of an aminosilane thin film able to graft palladium directly on its amine functional groups. After deposition of the different Pd anchoring layers, two Ni plating baths were used which have allowed to deposit either high phosphorous (7-9 wt.%) or low phosphorous (1-3 wt.%) Ni-P films. Adhesion of such films was evaluated qualitatively by a Scotch(R)-tape test. These experiments have shown how important is the choice of the plating bath to match at best physical and mechanical properties of film and substrate in order to improve adhesion. (C) 2002 Elsevier Science B.V. All rights reserved.