GB855793A - Improvements in and relating to the electrodeposition of copper - Google Patents

Abstract

855,793. Electrodepositing bright cyanide copper. HARSHAW CHEMICAL CO. Jan. 17, 1957 [Jan 19, 1956], No. 1820/57. Class 41 Bright copper is electrodeposited from a plating bath comprising an aqueous solution of copper cyanide and as a brightener a N-heterocyclic six-membered ring compound containing the group -C=N- where C and N are members | #Y. of the ring and Y is a nuclear thio substitnent, e.g. mercaptic or mercaptide group. Preferably the bath contains per litre 85 to 225 gms of copper cyanide and from 125 to 350 gms of potassium cyanide including 2À5 to 25 gms of this as free cyanide and 0À15 to 10 gms of brightener which may be dithioammelide, thioammeline, or 2:4:6-trimercaptotrianine. Sodium cyanide may be used instead of potassium cyanide and brighteners having as ring substitutents alkyl or acyl (up to six carbon atoms), aryl, alkoxy, fluorine, chlorine, nitro or other non-interfering groups while the preferred compounds include a C-amino group. Rochelle salt may be included as a buffer although this causes some loss of brightness but the preferred buffer is 35 to 75 gms/litre of potassium citrate, while to improve the colour of the deposit up to 1 gm/litre of methylcarboxycellulose may be included. To increase the maximum cathode current density from 1 to 20 gms/ litre of formaldehyde may be added. Typically the bath is used at a temperature of 130‹ to 180 ‹F. and a pH of 9 to 14 with a cathode current density of 10 to 60 amps/sq. ft., preferably employing interrupted D.C.