Nickel cobalt phosphorus electroplating composition and its use in surface treatment of a workpiece

Abstract

A nickel cobalt phosphorus electroplating composition includes a nickel salt, a cobalt salt, a phosphite-containing compound, and a multidentate chelating agent selected from triethylene tetraamine, diethylene triamine, hydrazobenzene, and combinations thereof. An electroplating solution including the nickel cobalt phosphorus electroplating composition and a method for treating a surface of a workpiece using the electroplating solution are also disclosed.

1 . A nickel cobalt phosphorus electroplating composition, comprising: 
 a nickel salt;    a cobalt salt;    a phosphite-containing compound; and    a multidentate chelating agent selected from the group consisting of triethylene tetraamine, diethylene triamine, hydrazobenzene, and combinations thereof.    
   
   
       2 . The nickel cobalt phosphorus electroplating composition of  claim 1 , wherein the multidentate chelating agent is triethylene tetraamine.  
   
   
       3 . The nickel cobalt phosphorus electroplating composition of  claim 1 , wherein the phosphite-containing compound is a sodium-free phosphite-containing compound selected from the group consisting of phosphorous acid, nickel phosphite, cobalt phosphite and combinations thereof.  
   
   
       4 . The nickel cobalt phosphorus electroplating composition of  claim 3 , wherein the phosphite-containing compound is phosphorous acid.  
   
   
       5 . The nickel cobalt phosphorus electroplating composition of  claim 1 , wherein the nickel salt is selected from the group consisting of nickel carbonate, nickel hydroxide, nickel oxide, and combinations thereof.  
   
   
       6 . The nickel cobalt phosphorus electroplating composition of  claim 1 , wherein the cobalt salt is selected from the group consisting of cobalt carbonate, cobalt hydroxide, cobalt oxide, and combinations thereof.  
   
   
       7 . An electroplating solution comprising a nickel cobalt phosphorus electroplating composition and water, the nickel cobalt phosphorous electroplating composition comprising: a nickel salt dissolved in the water to form nickel ions; a cobalt salt dissolved in the water to form cobalt ions; a phosphite-containing compound dissolved in the water to form phosphite ions; and a multidentate chelating agent dissolved in the water and selected from the group consisting of triethylene tetraamine, diethylene triamine, hydrazobenzene, and combinations thereof; wherein the electroplating solution has a pH value ranging from 0.2 to 5.  
   
   
       8 . The electroplating solution of  claim 7 , wherein the pH value ranges from 1.2 to 2.  
   
   
       9 . The electroplating solution of  claim 7 , wherein the pH value ranges from 1.5 to 1.9.  
   
   
       10 . The electroplating solution of  claim 7 , further comprising an electrolyte selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloride, and combinations thereof.  
   
   
       11 . The electroplating solution of  claim 10 , wherein the concentration of the nickel ions ranges from 20 to 100 g/l, the concentration of the cobalt ions ranges from 0.5 to 15 g/l, the concentration of the phosphite ions ranges from 5 to 80 g/l, the concentration of the electrolyte ranges from 20 to 200 g/l, and the concentration of the multidentate chelating agent ranges from 20 to 200 g/l.  
   
   
       12 . The electroplating solution of  claim 11 , wherein the concentration of the nickel ions ranges from 40 to 70 g/l, the concentration of the cobalt ions ranges from 4 to 7 g/l, the concentration of the phosphite ions ranges from 20 to 40 g/l, the concentration of the electrolyte ranges from 100 to 140 g/l, and the concentration of the multidentate chelating agent ranges from 60 to 120 g/l.  
   
   
       13 . The electroplating solution of  claim 12 , wherein the concentration of the nickel ions is 55 g/l, the concentration of the cobalt ions is 5.5 g/l, the concentration of the phosphite ions is 30 g/l, the concentration of the electrolyte is 120 g/l, and the concentration of the multidentate chelating agent is 90 g/l.  
   
   
       14 . The electroplating solution of  claim 10 , wherein the electrolyte is phosphoric acid.  
   
   
       15 . The electroplating solution of  claim 14 , wherein the multidentate chelating agent is triethylene tetraamine.  
   
   
       16 . A method for treating a surface of a workpiece, comprising: 
 placing the workpiece in an electroplating solution including a nickel cobalt phosphorus electroplating composition; and    electroplating the workpiece in the electroplating solution under a current density so as to form a nickel cobalt phosphorus electrodeposit to on the surface of the workpiece,    wherein the nickel cobalt phosphorus electroplating composition includes a nickel salt, a cobalt salt, a phosphite-containing compound, and a multidentate chelating agent selected from the group consisting of triethylene tetraamine, diethylene triamine, hydrazobenzene, and combinations thereof.    
   
   
       17 . The method of  claim 16 , wherein the nickel cobalt phosphorus electroplating composition further includes an electrolyte selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloride, and combinations thereof.  
   
   
       18 . The method of  claim 16 , wherein the electroplating solution is maintained at a temperature ranging from 40° C. to 70° C. during the electroplating of the workpiece in the electroplating solution.  
   
   
       19 . The method of  claim 18 , wherein the electroplating solution is maintained at a temperature ranging from 50° C. to 60° C.  
   
   
       20 . The method of  claim 16 , wherein the current density ranges from 0.5 to 10 A/dm 2  during the electroplating of the workpiece in the electroplating solution.  
   
   
       21 . The method of  claim 20 , wherein the current density ranges from 1.5 to 6 A/dm 2 .  
   
   
       22 . The method of  claim 16 , wherein the electroplating of the workpiece in the electroplating solution is conducted using an undissolvable anode.  
   
   
       23 . The method of  claim 22 , wherein the undissolvable anode is made from platinum titanium mesh.  
   
   
       24 . The method of  claim 16 , further comprising hot-working the electroplated workpiece after the electroplating of the workpiece in the electroplating solution.  
   
   
       25 . The method of  claim 24 , wherein the hot-working of the electroplated workpiece is conducted at a temperature ranging from 200° C. to 450°.