Boric acid-free satin nickel

Abstract

A nickel electrolyte for depositing a satin nickel layer that includes (a) at least one source of nickel ions, (b) at least one source of chloride ions, (c) at least one source of alkylsulfonic zwitterions, (d) a primary brightener, wherein the primary brightener comprises saccharine or a salt thereof, (e) at least one sulfonic acid, (f) at least one polymer and/or copolymer based on polyethylene glycol and/or polypropylene glycol, (g) optionally, at least one wetting agent, and (h) optionally, at least one additional brightener. A method of electrodepositing a satin nickel layer on a substrate is also included.

1 . An aqueous nickel electroplating bath comprising:
 a. at least one source of nickel ions;   b. at least one source of chloride ions;   c. at least one source of alkylsulfonic zwitterions;   d. a primary brightener, wherein the primary brightener comprises saccharine or a salt thereof;   e. at least one sulfonic acid;   f. at least one polymer and/or a copolymer based on polypropylene glycol and/or polyethylene glycol;   g. optionally, at least one wetting agent; and   h. optionally, at least one additional brightener;
 wherein the nickel electrolyte is capable of depositing a satin nickel layer on a substrate. 
   
     
     
         2 . The nickel electroplating bath according to  claim 1 , wherein the bath is at least substantially free of boric acid or a salt or a derivative thereof. 
     
     
         3 . The nickel electroplating bath according to  claim 1 , wherein the at least one source of alkylsulfonic zwitterions is selected from the group consisting of 2-aminoethane sulfonic acid, 2-aminopropane sulfonic acid, N-cylcohexyl-2-aminoetane sulfonic acid, N-[tri(hydroxymethyl)methyl]-3-aminopropane sulfonic acid, and combinations of one or more of the foregoing. 
     
     
         4 . The nickel electroplating bath according to  claim 1 , wherein the bath is maintained at a pH in the range of about 2.5 to about 5.5. 
     
     
         5 . The nickel electroplating bath according to  claim 4 , wherein the pH is maintained with sulfuric acid, hydrochloric acid, or combinations thereof. 
     
     
         6 . The nickel electroplating bath according to  claim 1 , wherein the bath is maintained at a temperature in the range of about 30 to about 70° C. 
     
     
         7 . The nickel electroplating bath according to  claim 1 , wherein the at least one source of nickel ions is selected from the group consisting of nickel sulfate, nickel chloride, and combinations of the foregoing. 
     
     
         8 . The nickel electroplating bath according to  claim 7 , wherein the at least one source of nickel ions comprises nickel chloride, wherein the nickel chloride provides a source of the at least one source of nickel ions and a source of the at least one source of chloride ions. 
     
     
         9 . The nickel electroplating bath according to  claim 8 , wherein the bath is at least substantially free of any other source of chloride ions. 
     
     
         10 . The nickel electroplating bath according to  claim 1 , wherein the primary brightener is selected from the group consisting of saccharine, sodium saccharine, calcium saccharine, silver saccharine, ammonium saccharine, cupric saccharine, lithium saccharine, magnesium saccharine, zinc saccharine, potassium saccharine, and combinations of one or more of the foregoing. 
     
     
         11 . The nickel electroplating bath according to  claim 10 , wherein the primary brightener comprises sodium saccharine. 
     
     
         12 . The nickel electroplating bath according to  claim 1 , wherein the at least one sulfonic acid is selected from the group consisting of methane sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, ethane sulfonic acid, propane sulfonic acid, propyne sulfonic acid, sulfonamides, sulfimides, N-sulfonylcarboxamides, sulfinates, and combinations of one more of the foregoing. 
     
     
         13 . The nickel electroplating bath according to  claim 12 , wherein the at least one sulfonic acid comprises allyl sulfonic acid. 
     
     
         14 . The nickel electroplating bath according to  claim 1 , wherein the at least one polymer is selected from the group consisting of a high-chain length polyethylene glycol, a low-chain polyethylene glycol derivative, a long-chain length polypropylene glycol, a low-chain length polypropylene glycol derivative, and combinations of one or more of the foregoing. 
     
     
         15 . The nickel electroplating bath according to  claim 1 , wherein the at least one wetting agent is present in the bath, and is selected from the group consisting of linear alkylsulfates with less than 18 carbons, branched alkylsulfates with less than 18 carbons, carboxylic sulfonic acid acids where the ester group is below the 12 th  carbon, fatty alcohol sulfated ethoxylates, naphthalene sulfonates, 2-ethylhexysulfate, di-alkylsulfosuccinate, polymerized naphthalenesulfonate, lauryl sulfate, lauryl ether sulfate, and combinations of one or more of the foregoing. 
     
     
         16 . The nickel electroplating bath according to  claim 1 , wherein the at least one additional brightener is present in the bath and is selected from the group consisting of pyridinium propyl sulfobetaine, sulfobetaines, propargyl alcohols and derivatives thereof, butynedioles and derivatives thereof, hexynedioles, and combinations of one or more of the foregoing. 
     
     
         17 . The nickel electroplating bath according to  claim 1 , wherein a total concentration of nickel is in the range of about 40 to about 110 g/L. 
     
     
         18 . The nickel electroplating bath according to  claim 17 , wherein the total concentration of nickel is in the range of about 60 to about 90 g/L. 
     
     
         19 . A method of electrodepositing a satin nickel layer onto a substrate, the method comprising the steps of:
 a) providing the substrate as the cathode to be plated in an electrolytic cell and at least one anode;   b) contacting the cathode and the at least one anode with the aqueous nickel electroplating bath according to  claim 1 ; and   c) supplying an electric current between the cathode and the at least one anode, wherein a satin nickel layer is deposited on a surface of the substrate.   
     
     
         20 . The method according to  claim 19 , wherein the substrate is pre-treated prior to step a). 
     
     
         21 . The method according to  claim 20 , wherein the pre-treating step includes degreasing and acid cleaning. 
     
     
         22 . The method according to  claim 19 , wherein the pH of the nickel electroplating bath is maintained at a pH within the range of 2.5 to 5.5. 
     
     
         23 . The method according to  claim 22 , wherein, the pH is maintained through the addition of sulfuric acid, hydrochloric acid, or combinations thereof. 
     
     
         24 . The method according to  claim 19 , wherein the satin nickel layer has a gloss value in the range of about 5 to about 500 GU when measured at a 60° angle. 
     
     
         25 . The method according to  claim 24 , wherein the gloss value is in the range of about 20 to about 100 GU when measured at a 60° angle. 
     
     
         26 . The method according to  claim 19 , wherein the satin nickel layer is at least substantially free of any pinholes and defects. 
     
     
         27 . The method according to  claim 19 , wherein the substrate is selected from the group consisting of magnesium, aluminum, copper, zinc, brass, bronze, steel, vanadium, chromium, manganese, iron, cobalt, nickel, rubidium, rhodium, palladium, silver, indium, tin, antimony, tellurium, rhenium, platinum, gold, thallium, bismuth, various plastics, and combinations of one or more of the foregoing. 
     
     
         28 . The method according to  claim 19 , wherein the at least one anode comprises a nickel anode. 
     
     
         29 . The method according to  claim 19 , wherein the current applied to the substrate has a current density in the range of about 0.1 to about 25 A/dm 2 . 
     
     
         30 . The method according to  claim 19 , wherein the deposited nickel layer has a thickness in the range of about 2 to about 30 μm. 
     
     
         31 . The method according to  claim 19 , wherein the temperature of the nickel electroplating solution is maintained in the range of about 30 to about 70° C. 
     
     
         32 . A substrate having a satin nickel layer thereon made by the method of  claim 19 . 
     
     
         33 . The substrate according to  claim 32 , wherein the satin nickel layer exhibits a gloss value in the range of about 5 to about 500 GU when measured at a 60° angle. 
     
     
         34 . The substrate according to  claim 33 , wherein the gloss value is in the range of about 20 to about 100 GU when measured at a 60° angle. 
     
     
         35 . The substrate according to  claim 32 , wherein the satin nickel layer is at least substantially free of any pinholes and defects. 
     
     
         36 . The substrate according to  claim 32 , wherein the satin nickel layer exhibits a surface roughness average less than 10 μm. 
     
     
         37 . The substrate according to  claim 36 , wherein the surface roughness average of the satin nickel layer is in the range of about 0.3 to about 5.0 μm. 
     
     
         38 . The substrate according to  claim 37 , wherein the surface roughness average of the satin nickel layer is in the range of about 1.0 to about 2.5 μm.