US 12,006,585 B2
Method for depositing a chromium or chromium alloy layer and plating apparatus
Michael Muigg, Berlin (DE); Anke Walter, Berlin (DE); Matthias Rost, Berlin (DE); and Sebastian Kühne, Berlin (DE)
Assigned to Atotech Deutschland GmbH, Berlin (DE)
Appl. No. 17/312,968
Filed by Atotech Deutschland GmbH, Berlin (DE)
PCT Filed Dec. 11, 2019, PCT No. PCT/EP2019/084573
§ 371(c)(1), (2) Date Jun. 11, 2021,
PCT Pub. No. WO2020/120537, PCT Pub. Date Jun. 18, 2020.
Claims priority of application No. 18211585 (EP), filed on Dec. 11, 2018.
Prior Publication US 2022/0074063 A1, Mar. 10, 2022
Int. Cl. C25D 3/06 (2006.01); C25D 17/00 (2006.01); C25D 21/14 (2006.01); C25D 21/18 (2006.01)
CPC C25D 3/06 (2013.01) [C25D 17/00 (2013.01); C25D 21/14 (2013.01); C25D 21/18 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method for depositing a chromium or chromium alloy layer on at least one substrate, the method comprising the steps
(a) providing an aqueous deposition bath with a pH in the range from 4.1 to 6.9, the bath comprising
trivalent chromium ions,
formate ions,
sulfate ions, and
ammonium ions,
(b) providing the at least one substrate and at least one anode,
(c) immersing the at least one substrate in the aqueous deposition bath and applying an electrical current such that the chromium or chromium alloy layer is deposited on the substrate, the substrate being a cathode,
wherein, during or after step (c), when the trivalent chromium ions have a concentration that has fallen below a target concentration of trivalent chromium ions,
(d) adding dissolved trivalent chromium formate to the aqueous deposition bath such that trivalent chromium ions are present in a higher concentration than before step (d),
provided that
solid trivalent chromium formate is dissolved in a separated partial volume taken from the aqueous deposition bath to obtain said higher concentration of trivalent chromium ions for step (d),
wherein in step (a) the sulfate ions have a concentration ranging from 35 g/L to 90 g/L, based on the total volume of the deposition bath,
wherein in step (a) the aqueous deposition bath comprises the ammonium ions in a concentration from 30 g/L to 150 g/L, based on the total volume of the deposition bath.