Electroless nickel alloy plating baths, a method for deposition of nickel alloys, nickel alloy deposits and uses of such formed nickel alloy deposits

Abstract

The present invention relates to an electroless nickel alloy plating bath comprising nickel ions; further reducible metal ions selected from the group consisting of molybdenum ions, rhenium ions, tungsten ions, copper ions, oxo-ions thereof, and mixtures thereof; at least one reducing agent suitable to reduce the nickel ions and the further reducible metal ions to their respective metallic state; complexing agents CA1, CA2, CA3, and CA4, wherein CA1, CA2, CA3, and CA4 are all different from each other, wherein each of CA1 and CA2 is independently selected from the group consisting of compounds having at least two carboxylic acid moieties, the respective salts thereof as well as mixtures of the aforementioned; wherein CA3 is selected from the group consisting of aliphatic compounds having exactly one carboxylic acid moiety, the respective salts thereof as well as mixtures of the aforementioned; and wherein CA4 is selected from the group consisting of aromatic compounds having at least one carboxylic acid moiety, the respective salts thereof as well as mixtures of the aforementioned.

1 . An electroless nickel alloy plating bath comprising
 a) nickel ions;   b) further reducible metal ions selected from the group consisting of molybdenum ions, rhenium ions, tungsten ions, copper ions, oxo-ions thereof, and mixtures thereof;   c) at least one reducing agent suitable to reduce the nickel ions and the further reducible metal ions to their respective metallic state;   d) complexing agents CA1, CA2, CA3, and, CA4, wherein CA1, CA2, CA3, and CA4 are all different from each other;
 wherein each of CA1 and CA2 is independently selected from the group consisting of compounds having at least two carboxylic acid moieties, the respective salts thereof as well as mixtures of the aforementioned; 
 wherein CA3 is selected from the group consisting of aliphatic compounds having exactly one carboxylic acid moiety, the respective salts thereof as well as mixtures of the aforementioned; and 
 wherein CA4 is selected from the group consisting of aromatic compounds having at least one carboxylic acid moiety, the respective salts thereof as well as mixtures of the aforementioned. 
   
     
     
         2 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agents CA1 and CA2 are independently selected from the group consisting of unfunctionalized and functionalized aliphatic dicarboxylic acids, unfunctionalized and functionalized aliphatic tricarboxylic acids, unfunctionalized and functionalized aliphatic tetracarboxylic acids, unfunctionalized and functionalized aliphatic pentacarboxylic acids, unfunctionalized and functionalized aliphatic hexacarboxylic acids, the respective salts thereof as well as mixtures of the aforementioned. 
     
     
         3 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA1 is an unfunctionalized aliphatic C2-C12-dicarboxylic acid and/or salts thereof. 
     
     
         4 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA1 is selected from the group consisting of malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, glutaconic acid, itaconic acid, salts thereof, and mixtures of the aforementioned. 
     
     
         5 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA2 is a functionalized or unfunctionalized aliphatic C3-C12-dicarboxylic acid and/or salts thereof. 
     
     
         6 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA2 is selected from the group consisting of malic acid, tartaric acid, 1-hydroxyglutaric acid, 2-hydroxyglutaric acid, 1-hydroxyadipic acid, 2-hydroxyadipic acid, 3-hydroxyadipic acid, salts thereof, and mixtures of the aforementioned. 
     
     
         7 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA3 is a functionalized or unfunctionalized aliphatic C1-C5-monocarboxylic acid and/or salts thereof. 
     
     
         8 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA4 is a functionalized or unfunctionalized aromatic carboxylic acid and/or salts thereof. 
     
     
         9 . The electroless nickel alloy plating bath according to  claim 1  characterized in that it has a pH value ranging from 3.5 to 5.0. 
     
     
         10 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the further reducible metal ions are molybdenum ions, copper ions, or a mixture thereof. 
     
     
         11 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the further reducible metal ions have a total concentration ranging from 1*10 −4  to 5*10 −3  mol/L, based on the total volume of the electroless nickel alloy plating bath. 
     
     
         12 . (canceled) 
     
     
         13 . A method for depositing nickel alloys on at least one surface of a substrate comprising in this order the following method steps
 A) providing the substrate comprising the at least one surface;   B) contacting the at least one surface of the substrate with an electroless nickel alloy plating bath according to  claim 1  and thereby depositing a nickel alloy on the at least one surface of the substrate.   
     
     
         14 . A nickel alloy deposit obtainable by deposition from the electroless nickel alloy plating bath of  claim 1 . 
     
     
         15 . (canceled) 
     
     
         16 . The electroless nickel alloy plating bath according to  claim 1  wherein the at least one reducing agent is selected from the group consisting of hypophosphorous acid, hypophosphite salts and mixtures of the aforementioned. 
     
     
         17 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the bath is free of thiourea. 
     
     
         18 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA3 is propionic acid and/or salts thereof. 
     
     
         19 . The electroless nickel alloy plating bath according to  claim 1  characterized in that the complexing agent CA4 is benzoic acid and/or salts thereof. 
     
     
         20 . The electroless nickel alloy plating bath according to  claim 1  characterized in that:
 CA1 is malonic acid and/or salts thereof, 
 CA2 is malic acid and/or salts thereof, 
 CA3 is propionic acid and/or salts thereof, and 
 CA4 is benzoic acid and/or salts thereof. 
 
     
     
         21 . The method of  claim 13  characterized in that the nickel alloy has a content of phosphorous ranging from 10.0 to 16.0 wt.-%.