PROCESS FOR APPLYING A METAL COATING TO A NON-CONDUCTIVE SUBSTRATE
Described is a new process for applying a metal coating to a non-conductive substrate comprising the steps of (a) contacting the substrate with an activator comprising a noble metal/group IVA metal sol to obtain a treated substrate, (b) contacting said treated substrate with a composition comprising a solution of: (i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof, (ii) 0.05 to 5 mol/l of a group IA metal hydroxide and (iii) a complexing agent for an ion of the metal of said metal salt comprising an organic material having a cumulative formation constant log K of from about 0.73 to about 21.95 for an ion of the metal of said metal salt, characterised in that the composition according to step (b) is treated with an electrical current for a period of time prior to and/or during contacting said solution with the substrate.
1 . A process for applying a metal coating to a non-conductive substrate comprising the steps of
(a) contacting the substrate with an activator comprising a noble metal/group IVA metal sol to obtain a treated substrate,
(b) contacting said treated substrate with a composition comprising a solution of:
(i) a Cu(II), Ag, Au or Ni soluble metal salt or mixtures thereof,
(ii) a source of hydroxide ions and
(iii) a complexing agent for an ion of the metal of said metal salt comprising an organic material having a cumulative formation constant log K of from about 0.73 to about 21.95 for an ion of the metal of said metal salt,
characterised in that the composition according to step (b) is treated with an electrical current for a period of time prior to and/or during contacting said solution with the substrate and
(c) electrolytically coating a metal on said coated non-conductive substrate to obtain an electrolytically treated substrate.
2 . The process according to claim 1 wherein the electrical current is applied during contacting said solution with the substrate.
3 . The process according to claim 1 wherein the electrical current ranges between 0.05 and 1 A/dm 2 .
4 . The process claim 1 wherein the anode to provide the electrical current is a stainless steel, a copper, a copper alloy, a titanium, a platinized titanium, a graphite, an iridium or a rhodium anode.
5 . The process according to claim 1 wherein the cathode is a stainless steel, a copper, a titanium, a platinized titanium, a graphite, an iridium or a rhodium cathode.
6 . The process according to claim 1 wherein the noble metal in the solution 1 (a) is palladium and the group IVA metal is tin.
7 . The process according to claim 1 wherein the salt in the solution 1 (b) (i) is a Cu(II) salt.
8 . The process according to claim 1 wherein the concentration of hydroxide ions in the solution 1 (b) (ii) is between 0.05 to 5 mol/l.
9 . The process according to claim 1 wherein the source of hydroxide ions in the solution 1 (b) (ii) is a group IA metal hydroxide.
10 . The process according to claim 1 wherein the complexing agent is used in an amount of 0.005 to 1 mol/l.
11 . The process according to claim 1 wherein the complexing agent is selected from the group consisting of iminosuccinic acid, gluconic acid, lactic acid, acetic acid, tartaric acid and salts thereof.
12 . The process according to claim 1 wherein the composition according to 1(b) does not contain an added reducing agent.
13 . (canceled)
14 . The process according to claim 1 wherein the metal coated electrolytically is selected from the group consisting of copper, nickel and chromium.