Cyanide-free silver electroplating solutions

1. A solution comprising one or more sources of silver ions, one or more complexing agents chosen from hydantoin, hydantoin derivatives, succinimide and succinimide derivatives, one or more organic sulfides chosen from dialkyl sulfides, substituted dialkyl sulfides, dialkyl disulfides and substituted dialkyl disulfides, and one or more pyridyl acrylic acids, the solution is cyanide-free.

2. The solution of claim 1 , wherein the pyridyl acrylic acids are chosen from 3-(2-pyridyl)acrylic acid, cis-3-(3-pyridyl)acrylic acid, 3-(4-pyridyl)acrylic acid, 3-(6-phenyl-pyridyl)acrylic acid, trans-3-(3-pyridyl)acrylic acid and z-2-fluoro-3-(3-pyridyl)acrylic acid.

3. The solution of claim 1 , wherein the hydantoin derivatives are chosen from hydantoin, 1-methylhydantoin, 1,3-dimethylhydantoin, 5,5-dimethylhydantoin, 1-methanol-5,5-dimethylhydantoin and 5,5-diphenylhydantoin.

4. The solution of claim 1 , wherein the substituted dialkyl sulfide is a β-thiodialkanol.

5. A method comprising:

a) providing a solution comprising one or more sources of silver ions, one or more complexing agents chosen from hydantoin, hydantoin derivatives, succinimide and succinimide derivatives, one or more organic sulfides chosen from dialkyl sulfides, substituted dialkyl sulfides, dialkyl disulfides and substituted dialkyl disulfides, and one or more pyridyl acrylic acids, the solution is cyanide-free;

b) contacting a substrate with the solution; and

c) electroplating a silver onto the substrate.

6. The method of claim 5 , wherein a current density is equal to or greater than 5 A/dm 2 .

7. The method of claim 6 , wherein the current density is from 6 A/dm 2 to 15 A/dm 2 .

8. The method of claim 5 , wherein a temperature of the solution is 30° C. to 90° C.