Electrolyte Solution and Electropolishing Methods
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)