Methods of refreshing plating baths containing phosphate anions
AssigneeHoneywell International Inc.
InventorsGangmin CAO, Jingkang LV
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Abstract
Methods of refreshing plating solutions containing phosphate anions, refreshed plating solutions, and uses thereof are described. The method may include adding a metal sulfate to the plating solution; precipitating out phosphate anions present in the plating solution with metal ions from the metal sulfate; adding barium carbonate to the plating solution; precipitating sulfate introduced from the metal sulfate added to the plating solution with barium from the barium carbonate; separating insoluble components from the plating solution; and replenishing the plating solution with components originally present in the plating solution.
Claims20
A method of refreshing a plating solution, the method comprising:
- adding a metal sulfate to the plating solution;
- precipitating out phosphate anions present in the plating solution with metal ions from the metal sulfate;
- adding barium carbonate to the plating solution;
- precipitating sulfate introduced from the metal sulfate added to the plating solution with barium from the barium carbonate;
- separating insoluble components from the plating solution;
- and
- replenishing the plating solution with components originally present in the plating solution.
A method of assessing a refreshed plating solution, the method comprising:
- (a) generating a refreshed plating solution from a plating solution after the plating solution has been aged from an original plating solution;
- (b) electroplating a dummy cathode with the refreshed plating solution;
- and
- (c) comparing properties of a coating produced in step b. with properties of a coating produced by electroplating with the original plating solution.
A method of refreshing a plating solution containing a plating metal, the method comprising:
- determining a total amount of phosphite anions and phosphate anions in the plating solution;
- determining an amount of a metal sulfate compound required to precipitate the total amount of phosphite anions and phosphate anions;
- adding the determined amount of the metal sulfate compound to the plating solution;
- maintaining the metal sulfate compound in the plating solution for a period of time sufficient to achieve precipitation of the total amount of phosphite anions and phosphate anions;
- determining an amount of barium carbonate needed to precipitate the amount of sulfate introduced from the metal sulfate compound added to the plating solution;
- adding the determined amount of barium carbonate to the plating solution;
- maintaining the barium carbonate in the plating solution to achieve precipitation of the sulfate;
- separating the precipitates from the plating solution;
- adjusting a pH of the plating solution to cause precipitation;
- and
- adding components back to the plating solution to produce a refreshed plating solution.
Dependencies are inferred from the claim text.