Electrolyte Solution and Electropolishing Methods

Abstract

An aqueous electrolyte solution including a concentration of citric acid in the range of about 1.6 g/L to about 982 g/L and an effective concentration of ammonium bifluoride (ABF), and being substantially free of a strong acid. Methods of micropolishing a surface of a non-ferrous metal workpiece including exposing the surface to a bath of an aqueous electrolyte solution including a concentration of citric acid in the range of about 1.6 g/L to about 780 g/L and a concentration of ammonium bifluoride in the range of about 2 g/L to about 120 g/L and having no more than about 3.35 g/L of a strong acid, controlling the temperature of the bath to be between the freezing point and the boiling point of the solution, connecting the workpiece to an anodic electrode of a DC power supply and immersing a cathodic electrode of the DC power supply in the bath, and applying a current across the bath.

1 . An aqueous electrolyte solution comprising:
 a concentration of citric acid in the range of about 1.6 g/L to about 982 g/L; and   an effective concentration of ammonium bifluoride (ABF); and   being substantially free of a strong acid.   
     
     
         2 . The aqueous electrolyte solution of  claim 1 , wherein the effective concentration of ammonium bifluoride is at least about 2 g/L. 
     
     
         3 . The aqueous electrolyte solution of  claim 2 , wherein the effective concentration of ammonium bifluoride is less than or equal to a saturation concentration in water. 
     
     
         4 . The aqueous electrolyte solution of  claim 2 , wherein the effective concentration of ammonium bifluoride is in the range of about 10 g/L to about 120 g/L. 
     
     
         5 . The aqueous electrolyte solution of  claim 1 , wherein the concentration of citric acid is less than or equal to about 780 g/L. 
     
     
         6 . The aqueous electrolyte solution of  claim 5 , wherein the concentration of citric acid is greater than about 0 g/L and less than or equal to about 600 g/L. 
     
     
         7 . The aqueous electrolyte solution of  claim 5 , wherein the concentration of citric acid is greater or equal to about 600 g/L and less than or equal to about 780 g/L. 
     
     
         8 . The aqueous electrolyte solution of  claim 1 , wherein substantially free of a strong acid means having no more than about 1 g/L of strong acid. 
     
     
         9 . The aqueous electrolyte solution of  claim 8 , wherein substantially free of a strong acid means having no more than about 0.35 g/L of a strong acid. 
     
     
         10 . The aqueous electrolyte solution of  claim 1 ,
 wherein the concentration of citric acid is in the range of about 60 g/L to about 780 g/L;   wherein the effective concentration of ammonium bifluoride is in the range of about 10 g/L to about 120 g/L; and   wherein substantially free of a strong acid means having no more than about 1 g/L of a strong acid.   
     
     
         11 . The aqueous electrolyte solution of  claim 10 ,
 wherein the concentration of citric acid is in greater than or equal to about 600 g/L; and   wherein the effective concentration of ammonium bifluoride is less than about 20 g/L.   
     
     
         12 . The aqueous electrolyte solution of  claim 10 ,
 wherein the citric acid concentration is greater than or equal to about 120 g/L and less than about 600 g/L.   
     
     
         13 . An aqueous electrolyte solution comprising:
 a concentration of citric acid greater than or equal to about 1.6 g/L and less than or equal to a saturation concentration; and   a concentration of ammonium bifluoride greater than or equal to about 2 g/L and less than or equal to a saturation concentration; and   having no more than about 3.35 g/L of strong acid.   
     
     
         14 - 36 . (canceled)