US 11,851,780 B2
Method for electrolytically passivating a surface of silver, silver alloy, gold, or gold alloy
Robert Rüther, Berlin (DE); Olaf Kurtz, Berlin (DE); Joko Setyadi-Lie, Berlin (DE); and Tse-Cheen Foong, Berlin (DE)
Assigned to Atotech Deutschland Gmbh & Co. KG, Berlin (DE)
Filed by Atotech Deutschland GmbH & Co. KG, Berlin (DE)
Filed on Aug. 15, 2022, as Appl. No. 17/888,160.
Application 17/888,160 is a division of application No. 17/284,902, granted, now 11,447,884, previously published as PCT/EP2019/078345, filed on Oct. 18, 2019.
Claims priority of application No. 18201553 (EP), filed on Oct. 19, 2018.
Prior Publication US 2022/0389603 A1, Dec. 8, 2022
Int. Cl. C25D 3/06 (2006.01); C25D 3/10 (2006.01)
CPC C25D 3/06 (2013.01) 7 Claims
 
1. An aqueous passivation solution having a pH in the range from 5.4 to 7.2, the solution comprising:
trivalent chromium ions, wherein the trivalent chromium ions are present in a concentration in the range from 0.1 g/L to 5.0 g/L, based on the total volume of the passivation solution, and
formate anions and/or oxalate anions as complexing agents for said trivalent chromium ions,
wherein the trivalent chromium ions with respect to all formate anions together with all oxalate anions form a molar ratio in the range from 1:40 to 1:250.