US 10,889,907 B2
Cyanide-free acidic matte silver electroplating compositions and methods
Adolphe Foyet, Lucerne (CH); Wan Zhang-Beglinger, Adligenswil (CH); and Margit Clauss, Kriens (CH)
Assigned to Rohm and Haas Electronic Materials LLC, Marlborough, MA (US)
Filed by Rohm and Haas Electronic Materials LLC, Marlborough, MA (US)
Filed on Feb. 21, 2014, as Appl. No. 14/186,081.
Prior Publication US 2015/0240375 A1, Aug. 27, 2015
Int. Cl. C25D 3/46 (2006.01)
CPC C25D 3/46 (2013.01) 6 Claims
OG exemplary drawing
 
1. A method of electroplating silver comprising:
a) contacting a substrate with an acidic silver electroplating composition consisting of one or more sources of silver ions, wherein the one or more sources of silver ions are in amounts of 10 g/L to 80 g/L, one or more alkanesulfonic acids in amounts of 20 g/L to 250 g/L, telluric acid in amounts of 200 mg/L to 800 mg/L, water, a pH of 1 to less than 1, one or more optional compounds chosen from suppressors, surfactants and grain refiners, one or more dihydroxy bis-sulfide compounds in amounts of 10 g/L to 80 g/L, wherein the one or more dihydroxy bis-sulfide compounds are chosen from 2,4-dithia-1,5-pentanediol, 2,5-dithia-1,6-hexanediol, 2,6-dithia-1,7-heptanediol, 2,7-dithia-1,8-octanediol, 3,5-dithia-1,7-heptanediol, and 3,6-dithia-1,8-octanediol, and one or more mercaptotetrazoles in amounts of 5 g/L to 160 g/L, wherein the one or more mercaptotetrazoles are chosen from 1-(2-dimethylaminoethyl)-5-mercapto-1,2,3,4-tetrazole, and 1-(2-diethylaminoethyl)-5-mercapto-1,2,3,4-tetrazole, the acidic silver electroplating composition is substantially free of cyanide, wherein a ratio of a concentration of the one or more mercaptotetrazoles to a concentration of the one or more dihydroxy bis-sulfide compounds is 0.5:1 to 2:1; and
b) electroplating uniform matte silver on the substrate with the acidic silver electroplating composition at a current density from 2-26 A/dm2 and a temperature of 60-70° C.