Self assembled molecules on immersion silver coatings
View Patent ↗A composition for enhancing the corrosion resistance of an article comprising a silver coating deposited on a solderable copper substrate. The composition comprises: a) a multi-functional molecule comprising at least one organic functional group that interacts with and protects copper surfaces and at least one organic functional group that interacts with and protects silver surfaces; b) an alcohol; and c) a surfactant.
1. A composition for enhancing the corrosion resistance of an article comprising a silver coating deposited on a solderable copper substrate, the composition comprising:
a multi-functional molecule, wherein the multi-functional molecules comprises at least one sulfur-containing organic functional group that interacts with and protects silver surfaces and at least one nitrogen-containing organic functional group that interacts with and protects copper surfaces, wherein the nitrogen-containing functional group comprises one of an amine or aromatic heterocycle;
an alcohol;
a surfactant; and
an alkaline pH adjuster.
2. The composition of claim 1 wherein the nitrogen-containing functional group comprises the amine.
3. The composition of claim 1 wherein the nitrogen-containing functional group comprises one of a primary amine, secondary amine, tertiary amine, or aromatic heterocycle.
4. The composition of claim 1 wherein the nitrogen-containing functional group comprises an azole.
5. The composition of claim 1 wherein the nitrogen-containing functional group comprises a benzimidazole.
6. The composition of claim 1 wherein the sulfur-containing functional group comprises one of a thiol, disulfide, thioether, thioaldehyde, thioketone, or aromatic heterocycle.
7. The composition of claim 3 wherein the sulfur-containing functional group comprises one of a thiol, disulfide, thioether, thioaldehyde, thioketone, or aromatic heterocycle.
8. The composition of claim 5 wherein the sulfur-containing functional group comprises one of a thiol, disulfide, thioether, thioaldehyde, thioketone, or aromatic heterocycle.
9. The composition of claim 1 wherein the sulfur-containing functional group comprises a thiol.
10. The composition of claim 1 wherein the sulfur-containing functional group comprises a disulfide.
11. The composition of claim 1 wherein the multi-functional molecule comprises azole and thiol functional groups.
12. The composition of claim 1 wherein the multi-functional molecule has one of the following structures:
wherein R 1 is hydrocarbyl and R 2 , R 3 , and R 4 are nitrogen, sulfur, or carbon; the carbon chain of the hydrocarbyl comprises between two and about 24 carbon atoms; and any of the carbon chain of the hydrocarbyl, R 2 , R 3 , and R 4 may be substituted or unsubstituted.
13. The composition of claim 3 wherein the multi-functional molecule has one of the following structures:
wherein R 1 is hydrocarbyl and R 2 , R 3 , and R 4 are nitrogen, sulfur, or carbon; the carbon chain of the hydrocarbyl comprises between two and about 24 carbon atoms; and any of the carbon chain of the hydrocarbyl, R 2 , R 3 , and R 4 may be substituted or unsubstituted.
14. The composition of claim 5 wherein the multi-functional molecule has one of the following structures:
wherein R 1 is hydrocarbyl and R 2 , R 3 , and R 4 are nitrogen, sulfur, or carbon; the carbon chain of the hydrocarbyl comprises between two and about 24 carbon atoms; and any of the carbon chain of the hydrocarbyl, R 2 , R 3 , and R 4 may be substituted or unsubstituted.
15. The composition of claim 1 wherein the alcohol is present in a concentration between about 10 mL/L and about 500 mL/L.
16. The composition of claim 1 wherein the surfactant is non-ionic.
17. The composition of claim 1 wherein the multi-functional molecule is present in a concentration between about 0.1 g/L and about 10 g/L.
18. The composition of claim 1 wherein:
the alcohol is present in a concentration between about 10 mL/L and about 500 mL/L;
the surfactant is non-ionic and present in a concentration between about 0.01 g/L and about 2 g/L; and
the multi-functional molecule is present in a concentration between about 0.1 g/L and about 10 g/L.
19. The composition of claim 1 wherein:
the alcohol is present in a concentration between about 10 mL/L and about 500 mL/L;
the surfactant is non-ionic and present in a concentration between about 0.01 g/L and about 2 g/L; and
the multi-functional molecule is present in a concentration between about 0.1 g/L and about 10 g/L.
20. The composition of claim 1 wherein the composition is free of alkali metal hydroxide.
21. An article comprising a silver coating on a copper substrate, with a protective organic film over the silver coating formed by exposing the copper substrate having the silver coating thereon to the anti-corrosion composition of claim 1 .