Method for producing matt copper deposits

Abstract

The present invention relates to a method for deposition of a matte copper coating wherein a first copper layer is deposited from an aqueous copper electrolyte which does not contain an organic compound comprising divalent sulfur. A second copper layer is then deposited onto the first copper layer from an aqueous copper electrolyte comprising a first and a second water soluble sulfur-containing additive wherein the first water soluble sulfur-containing compound is an alkyl sulfonic acid derivative and the second water soluble sulfur-containing additive is an aromatic sulfonic acid derivative. The method provides copper layers with a homogeneous and adjustable matte appearance for decorative applications.

1 . A method for deposition of a matte copper coating comprising, in this order, the steps
 a. providing a substrate,   b. depositing a first copper layer onto the substrate from a first aqueous electrolyte comprising a source of copper ions, at least one acid and at least one polyether compound wherein said first electrolyte does not contain an organic compound comprising divalent sulfur   and   c. depositing a second copper layer onto the first copper layer from a second aqueous electrolyte comprising a source of copper ions, at least one acid, a first water soluble sulfur-containing additive selected from the group consisting of alkyl sulfonic acid derivatives and a second water soluble sulfur containing additive selected from the group consisting of aromatic sulfonic acid derivatives   
       wherein a current density is applied to the substrate during steps b and c. 
     
     
         2 . The method for deposition of a matte copper coating according to  claim 1  wherein the at least one polyether compound in the first electrolyte is selected from the group consisting of polyalkylene glycols and polyglycerines. 
     
     
         3 . The method for deposition of a matte copper coating according to  claim 1  wherein the at least one polyether compound in the first electrolyte is selected from the group consisting of poly(1,2,3-propantriol), poly(2,3-epoxy-1-propanol) and derivatives thereof. 
     
     
         4 . The method for deposition of a matte copper coating according to  claim 1  wherein the at least one polyether compound in the first electrolyte is selected from the group consisting of compounds according to formulae (1), (2) and (3): 
       
         
           
           
               
               
           
         
         wherein n is an integer from 1 to 80; 
       
       
         
           
           
               
               
           
         
         wherein n is an integer >1, m is an integer >1 with the proviso n+m is ≦30; 
       
       
         
           
           
               
               
           
         
         wherein n is an integer from 1 to 80; 
         and wherein 
         R 6 , R 7 , R 8  and R 9  are identical or different and are selected from the group comprising hydrogen, alkyl, acyl, phenyl and benzyl. 
       
     
     
         5 . The method for deposition of a matte copper coating according to  claim 4  wherein the molecular weight of the compounds according to formulae (1), (2) and (3) ranges from 160 to 6000 g/mol. 
     
     
         6 . The method for deposition of a matte copper coating according to  claim 1  wherein the concentration of the at least one polyether compound in the first electrolyte ranges from 0.005 g/l to g/l. 
     
     
         7 . The method for deposition of a matte copper coating according to  claim 1  wherein the first water soluble sulfur-containing additive in the second electrolyte is selected from the group consisting of compounds according to formulae (4) and (5):
   R 1 S—(CH 2 ) n —SO 3 R 2   (4)
 
   R 3 SO 3 —(CH 2 ) m —S—S—(CH 2 ) m —SO 3 R 3   (5)
 
 wherein 
 R 1  is selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, lithium, sodium, potassium and ammonium, 
 n ranges from 1 to 6, 
 R 2  is selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, lithium, sodium, potassium and ammonium, 
 R 3  is selected from the group consisting of hydrogen, methyl, ethyl, propyl, butyl, lithium, sodium, potassium and ammonium and 
 m ranges from 1 to 6. 
 
     
     
         8 . The method for deposition of a matte copper coating according to  claim 1  wherein the concentration of the first water soluble sulfur-containing additive in the second electrolyte ranges from 0.0001 to 0.05 g/l. 
     
     
         9 . The method for deposition of a matte copper coating according to  claim 1  wherein the second water soluble sulfur-containing additive in the second electrolyte is selected from the group consisting of compounds according to formulae (6) and (7):
   R 4 S y —X—SO 3 M  (6)
 
 wherein R 4  is selected from the group consisting of 
 
       
         
           
           
               
               
           
         
       
       and hydrogen;
 X is selected from the group consisting of 
 
       
         
           
           
               
               
           
         
         y is an integer from 1 to 4 and M is selected from the group consisting of hydrogen, sodium, potassium and ammonium; and 
       
       
         
           
           
               
               
           
         
         wherein R 5  is selected from the group consisting of H, SH and SO 3 M and M is selected from the group consisting of hydrogen, sodium, potassium and ammonium. 
       
     
     
         10 . The method for deposition of a matte copper coating according to  claim 1  wherein the concentration of the second water soluble sulfur-containing additive in the second electrolyte ranges from 0.005 to 1 g/l. 
     
     
         11 . The method for deposition of a matte copper coating according to  claim 1  wherein the second electrolyte further comprises at least one carrier additive. 
     
     
         12 . The method for deposition of a matte copper coating according to  claim 11  wherein the at least one carrier additive selected from the group consisting of polyvinylalcohol, carboxymethylcellulose, polyethylene glycol, polypropylene glycol, stearic acid polyglycolester, alkoxylated naphtoles, oleic acid polyglycolester, stearylalcoholpolyglycolether, nonylphenolpolyglycolether, octanolpolyalkylenglycolether, octanediol-bis(polyalkylenglycolether), poly-(ethyleneglycol-ran-propylenglycol), poly(ethylenglycol)-block-poly-(propyleneglycol)-block-poly(ethylenglycol) and poly(propylenglycol)-block-poly(ethylenglycol)-block-poly(propylenglycol). 
     
     
         13 . The method for deposition of a matte copper coating according to  claim 10  wherein the concentration of the at least one carrier additive in the second electrolyte ranges from 0.005 g/l to 5 g/l. 
     
     
         14 . The method for deposition of a matte copper coating according to  claim 11  wherein the concentration of the at least one carrier additive in the second electrolyte ranges from 0.005 g/l to 5 g/l.