Catalytic sensitization of substrates for metallization

Claim 1

In the method of coating a non-conductive substrate surface with a metal-containing deposit comprising the steps of: first, contacting the substrate with a solution of tin salt and then rinsing the same; second, contacting the substrate with a solution of palladium salt and thereafter contacting the substrate with a solution containing the desired metal to be deposited and reducing agent for such metal, whereby a non-uniform metal-containing deposit is formed, the improvement comprising the steps of: rinsing the tin salt contacted substrate with a rinse of water containing an alkaline buffering compound in an effective amount to provide a pH of about 7 to about 9 in the mixture of palladium salt solution and remaining rinse in contact with the substrate whereby a uniform metal-containing deposit results.