Electrolyte and process for the deposition of copper-tin alloy layers

Abstract

The present invention relates to an electrolyte and a process for depositing bronze alloys on consumer goods and industrial articles. The electrolyte of the invention comprises, in addition to the metals to be deposited and additives such as wetting agents, complexing agents and brighteners, in particular sulfur compounds which have a positive effect in the corresponding process for the deposition of the bronzes.

1 . A cyanide-free electrolyte for the deposition of copper-tin bronzes on consumer goods and industrial articles, which contains the metals to be deposited in the form of water-soluble salts, wherein
 the electrolyte comprises the following further constituents:   a) one or more alkylsulfonic acids;   b) an ionic wetting agent in the form of a salt of a sulfonated or sulfated aromatic alkyl aryl ether compound;   c) a complexing agent; and   d) a compound selected from the group consisting of dialkyl thioether derivatives.   
     
     
         2 . The electrolyte as claimed in  claim 1 , wherein it comprises copper and tin or copper, tin and zinc as metals to be deposited. 
     
     
         3 . The electrolyte as claimed in  claim 1 , wherein the metals to be deposited are present in ionically dissolved form, with the ion concentration of copper being in the range from 0.2 to 10 g/l of electrolyte, the ion concentration of tin being in the range from 1.0 to 20 g/l of electrolyte and, if present, the ion concentration of zinc being in the range from 1.0 to 20 g/l of electrolyte. 
     
     
         4 . The electrolyte as claimed in  claim 1 , wherein alkylsulfonic acids selected from the group consisting of methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid are used. 
     
     
         5 . The electrolyte as claimed in  claim 1 , wherein the alkanesulfonates of the metals to be deposited are used as water-soluble salts. 
     
     
         6 . The electrolyte as claimed in  claim 1 , wherein an alkyl aryl ether compound selected from the group consisting of β-naphthol ethoxylate, nonylphenol ethoxylate is used. 
     
     
         7 . The electrolyte as claimed in  claim 1 , wherein the alkali metal salts of the corresponding acids are used. 
     
     
         8 . The electrolyte as claimed in  claim 1 , wherein a complexing agent selected from the group consisting of oxalic acid, malonic acid, succinic acid, tartaric acid, malic acid, citric acid, maleic acid, glutaric acid, and adipic acid is used. 
     
     
         9 . The electrolyte as claimed in  claim 1 , wherein a dialkyl thioether derivative selected from the group consisting of thiodiglycol propoxylate, thiodiglycol, thiodiglycerol, thiodiglycol ethoxylate, thiodiethylene bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), 2-amino-4-(methylthio)butanoic acid, 2,2′-thiodiethanethiol, 3,3′-thiodipropanethiol, 2,2′-thiodiacetic acid, 3,3′-thiodipropionic acid, diethyl 2,2′-thiodiacetate, dimethyl 2,2′-thiodiacetate, dioctyl 2,2′-thiodiacetate, didodecyl 2,2′-thiodiacetate, didodecyl 3,3′-thiodipropionate, dimethyl 3,3′-thiodipropionate, diethyl 3,3′-thiodipropionate, dioctyl 3,3′-thiodipropionate, 3,3′-thiodipropanol, 2,2′-thiodiethanol, 4,4′-thiodibutanol, 1,1′-(thiodi-2,1-ethanediyl)2-propionate, and dioctadecyl 3,3′-thiodipropionate is used. 
     
     
         10 . The electrolyte as claimed in  claim 1 , and wherein the pH of the electrolyte is in the range from −1 to 4. 
     
     
         11 . A process for the electrochemical deposition of copper-tin bronzes on consumer goods and industrial articles, which contains the metals to be deposited in the form of water-soluble salts, wherein the substrates to be coated are dipped into an electrolyte and an appropriate flow of current is provided, wherein an electrolyte as claimed in  claim 1  is used. 
     
     
         12 . The process as claimed in  claim 11 , wherein the electrolyte is heated to a temperature in the range from 20 to 40° C. during the deposition of the metals. 
     
     
         13 . The process as claimed in  claim 11 , wherein a current density which is in the range from 0.01 to 100 Ampere per square decimeter is set. 
     
     
         14 . The process as claimed in  claim 11 , wherein the soluble anodes composed of a material selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, copper-tin alloy, copper-zinc alloy and copper-tin-zinc alloy or combinations of these anodes are used.