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Adhesion of Electrodes Metal Films to Nonconductive Substrates

IP.com Disclosure Number: IPCOM000073388D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Koretzky, H: AUTHOR

Abstract

Tin compounds, especially SnCl(2), have been used extensively to sensitize nonconductive, noncatalytic substrates for subsequent electroless metal deposition. The substrate is suitably activated prior to deposition with divalent palladium salts in a typical case. It is believed that the adhesion of the electroless deposit is determined by two principle factors i.e., the number of adsorbed and active Sn sites and the degree of roughness of the surface on a microscale giving rise to mechanical keying or interlocks between the substrate and the conductive film. The sensitizer must be present in solution in its lowest stable valence state (Sn++) and that it adsorb onto the substrate surface to provide the greatest number of active sites to enhance adhesion.

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Adhesion of Electrodes Metal Films to Nonconductive Substrates

Tin compounds, especially SnCl(2), have been used extensively to sensitize nonconductive, noncatalytic substrates for subsequent electroless metal deposition. The substrate is suitably activated prior to deposition with divalent palladium salts in a typical case. It is believed that the adhesion of the electroless deposit is determined by two principle factors i.e., the number of adsorbed and active Sn sites and the degree of roughness of the surface on a microscale giving rise to mechanical keying or interlocks between the substrate and the conductive film. The sensitizer must be present in solution in its lowest stable valence state (Sn++) and that it adsorb onto the substrate surface to provide the greatest number of active sites to enhance adhesion.

The presence of a suitable metallic bar in the sensitizer solution avoids air oxidation and keeps the sensitizer in its reduced form. For example, a Sn or Fe metallic bar in the SnCl(2) system or Fe or the metal in the cases of other sensitizers, such as Ti, Zr and Th provide such action. Increased sensitizer nucleation is readily achieved by increasing the temperature of the water rinse which precedes the activation step from about room temperature (25 degrees C) to near boiling (95-98 degrees C). This procedure produces practically complete hydrolysis of the sensitizer without raising its oxidation state and provides the extra sites for activator red...