Metallic microstructures by electroplating on polymers: an alternative to LIGA technique

In this paper, a new technique of obtaining nickel electroplated layers on polymethylmethacrylate (PMMA) is presented. It consists of four steps. 1. Conditioning. Strongly oxidizing acid mixtures are used for providing ro ughness on the surface by generating suitable sites for chemical bonding of subsequently applied metals. 2. Nucleation. Using an acidic solution of a mixture of a palladium salt to gether with a tin salt it can be obtained an adsorbed film on PMMA's surfac e that is reduced to metallic form. 3. Electroless nickel plating. This step transforms PMMA into a conductive surface and builds up metal only to provide sufficient conductivity for ele ctroplating. This is achieved in a classical hypophosphite electroless nick el solution. 4. Nickel electroplating. Metallic microstructures are finally obtained by growing up, at the desired thickness, nickel layers on the thin electroless ones, using a standard sulphamate bath for rapid electroforming. This method of obtaining nickel electroplated microstructures was developed to replace the classical Lithographie, Galvanoformung, Abfolmung (LIGA) te chnique (mainly to avoid the use of the costly synchrotron system). (C) 200 0 Elsevier Science S.A. All rights reserved.