Anti-tarnish coatings

1. A method for enhancing the corrosion resistance of a surface of a copper or copper alloy substrate, the method comprising:

depositing a metallic surface layer comprising a precious metal on the surface of the copper or copper alloy substrate; and

exposing the copper or copper alloy substrate having the metallic surface layer thereon to an aqueous composition comprising (a) a first organic molecule comprising at least one functional group that interacts with and protects precious metal surfaces, said first molecule being elected from the group consisting of thiols (mercaptans), disulfides, thioethers, thioaldehydes, thioketones, and combinations thereof, (b) a second organic molecule comprising at least one functional group that interacts with and protects copper surfaces, said second molecule being elected from the group consisting of primary amines, secondary amines, tertiary amines, aromatic heterocycles comprising nitrogen, and combinations thereof and (c) a surfactant.

2. The method of claim 1 wherein the metallic surface layer is deposited by an immersion displacement plating process, and the metallic surface layer comprises silver, gold, or a combination thereof.

3. The method of claim 1 wherein the first organic molecule is a thiol having the following general structure (I):

R 1 —S—H  Structure (I)

wherein R 1 is either a hydrocarbyl having between one carbon atom and about 24 carbon atoms or an aryl having between about five and about fourteen carbon atoms.

4. The method of claim 3 wherein the thiol is selected from the group consisting of ethanethiol; 1-propanethiol; 2-propanethiol; 2-propene-1-thiol; 1-butanethiol; 2-butanethiol; 2-methyl-1-propanethiol; 2-methyl-2-propanethiol; 2-methyl-1-butanethiol; 1-pentanethiol; 2,2-dimethyl-1-propanethiol; 1-hexanethiol; 1,6-hexanedithiol; 1-heptanethiol; 2-ethylhexanethiol; 1-octanethiol; 1,8-octanedithiol; 1-nonanethiol; 1,9-nonanedithiol; 1-decanethiol; 1-adamantanethiol; 1,11-undecanedithiol; 1-undecanethiol; 1-dodecanethiol; tert-dodecylmercaptan; 1-tridecanethiol; 1-tetradecanethiol; 1-pentadecanethiol; 1-hexadecanethiol; 1-heptadecanethiol; 1-octadecanethiol; 1-nonadecanethiol; and 1-icosanethiol; and combinations thereof.

5. The method of claim 3 wherein the thiol is selected from the group consisting of benzenethiol; 2-methylbenzenethiol; 3-methylbenzenethiol; 4-methylbenzenethiol; 2-ethylbenzenethiol; 3-ethylbenzenethiol; 4-ethylbenzenethiol; 2-propylbenzenethiol; 3-propylbenzenethiol; 4-propylbenzenethiol; 2-tert-butylbenzenethiol; 4-tert-butylbenzenethiol; 4-pentylbenzenethiol; 4-hexylbenzenethiol; 4-heptylbenzenethiol; 4-octylbenzenethiol; 4-nonylbenzenethiol; 4-decylbenzenethiol; benzyl mercaptan; 2,4-xylenethiol, furfuryl mercaptan; 1-naphthalenethiol; 2-naphthalenethiol; 4,4′-dimercaptobiphenyl; and combinations thereof.

6. The method of claim 1 wherein the first organic molecule is a disulfide having the following structure (II):

R 1 —S—S—R 2   Structure (II)

wherein R 1 and R 2 are each independently either a hydrocarbyl having between one carbon atom and about 24 carbon atoms or an aryl having between about five and about fourteen carbon atoms.

7. The method of claim 6 wherein the disulfide is selected from the group consisting of diethyl disulfide, di-n-propyl disulfide, diisopropyl disulfide, diallyl disulfide, di-n-butyl disulfide, di-sec-butyl disulfide, diisobutyl disulfide, di-tert-butyl disulfide, di-n-pentyl disulfide, di-neopentyl disulfide, di-n-hexyl disulfide, di-n-heptyl disulfide, di-n-octyl disulfide, di-n-nonyl disulfide, di-n-decyl disulfide, di-n-dodecyl disulfide, di-n-tridecyl disulfide, di-n-tetradecyl disulfide, di-n-pentadecyl disulfide, di-n-hexadecyl disulfide, di-n-heptadecyl disulfide, di-n-octadecyl disulfide, di-n-decyl disulfide; diundecyl disulfide, didodecyl disulfide, dihexadecyl disulfide, dibenzyl disulfide, dithienyl disulfide, 2-naphthyl disulfide, and combinations thereof.

8. The method of claim 1 wherein the second organic molecule is a primary amine, secondary amine, or a tertiary amine having the following general structure (III):

wherein R 1 , R 2 , and R 3 are each independently hydrogen or a hydrocarbyl having between one carbon atom and about 24 carbon atoms, and at least one of R 1 , R 2 , and R 3 is a hydrocarbyl having between one carbon atom and about 24 carbon atoms.

9. The method of claim 8 wherein the amine is selected from the group consisting of aminoethane, 1-aminopropane, 2-aminopropane, 1-aminobutane, 2-aminobutane, 1-amino-2-methylpropane, 2-amino-2-methylpropane, 1-aminopentane, 2-aminopentane, 3-aminopentane, neo-pentylamine, 1-aminohexane, 1-aminoheptane, 2-aminoheptane, 1-aminooctane, 2-aminooctane, 1-aminononane, 1-aminodecane, 1-aminododecane, 1-aminotridecane, 1-aminotetradecane, 1-aminopentadecane, 1-aminohexadecane, 1-aminoheptadecane, 1-aminooctadecane, and combinations thereof.

10. The method of claim 1 wherein the second organic molecule is an azole having the following aeneral structure (IV):

wherein each of R 1 , R 2 , R 3 , R 4 , and R 5 is an atom selected from the group consisting of carbon and nitrogen wherein between one and four of the R 1 , R 2 , R 3 , R 4 , and R 5 groups are nitrogen and between one and four of the R 1 , R 2 , R 3 , R 4 , and R 5 groups are carbon; and R 11 , R 22 , R 33 , R 44 , and R 55 are each independently selected from the group consisting of hydrogen, carbon, sulfur, oxygen, and nitrogen.

11. The method of claim 10 wherein the azole is selected from the group consisting of pyrrole (1H-azole); imidazole (1,3-diazole); pyrazole (1,2-diazole); 1,2,3-triazole; 1,2,4-triazole; tetrazole; isoindole; indole (1H-benzo[b]pyrrole); benzimidazole (1,3-benzodiazole); indazole (1,2-benzodiazole); 1H-benzotriazole; 2H-benzotriazole; imidazo[4,5-b]pyridine; purine (7H-imidazo (4,5-d)pyrimidine); pyrazolo[3,4-d]pyrimidine; triazolo[4,5-d]pyrimidine; and combinations thereof.

12. The method of claim 10 wherein the azole is selected from the group consisting of 2-(3,4-dichlorobenzyl)-benzimidazole; 2-bromobenzyl benzimidazole; 2-bromophenyl benzimidazole; 2-bromoethylphenyl benzimidazole; 2-chlorobenzyl benzimidazole; 2-chlorophenyl benzimidazole; 2-chloroethylphenyl benzimidazole; and combinations thereof.

13. The method of claim 1 wherein the first organic molecule is present in a concentration between about 1 and about 10 g/L and the second organic molecule in a concentration between about 1 and about 10 g/L.

14. A process as set forth in claim 1 wherein said composition comprises an aqueous solution having a pH between about 7.0 and about 11.0.

15. A method for enhancing the corrosion resistance of a surface of a copper or copper alloy substrate, the method comprising:

depositing a metallic surface layer comprising silver and/or gold on the surface of the copper or copper alloy substrate; and

exposing the copper or copper alloy substrate having the metallic surface layer thereon to an aqueous composition comprising (a) a first organic molecule in a concentration between about 1 and about 10 g/L selected from the group consisting of thiols (mercaptans), disulfides, thioethers, thioaldehydes, thioketones, and combinations thereof that interacts with and protects precious metal surfaces, (b) a second organic molecule in a concentration between about 1 and about 10 g/L selected from the group consisting of primary amines, secondary amines, tertiary amines, aromatic heterocycles comprising nitrogen, and combinations thereof that interacts with and protects copper surfaces, and (c) a surfactant.

16. A process as set forth in claim 15 wherein said composition comprises an aqueous solution having a pH between about 7.0 and about 11.0.

17. A method for enhancing the corrosion resistance of a surface of a copper or copper alloy substrate, the method comprising:

depositing a metallic surface layer comprising silver and/or gold on the surface of the copper or copper alloy substrate; and

exposing the copper or copper alloy substrate having the metallic surface layer thereon to an aqueous composition comprising (a) a first organic molecule of 1-octadecanethiol in a concentration between about 1 and about 10 g/L, (b) a second organic molecule in a concentration between about 1 and about 10 g/L selected from the group consisting of primary amines, secondary amines, tertiary amines, aromatic heterocycles comprising nitrogen, and combinations thereof that interacts with and protects copper surfaces, and (c) a surfactant.

18. A process as set forth in claim 17 wherein said composition comprises an aqueous solution having a pH between about 7.0 and about 11.0.