Method of selectively monitoring trace constituents in plating baths
First Claim
1. A method of selectively monitoring the concentration of an organic addition agent present in a plating bath solution containing multiple trace constituents and metal ions wherein said organic addition agent is more rapidly absorbed than said trace constituents, said method comprising the steps of:
- providing at least one sensing electrode in contact with said solution;
applying a pretreatment signal of an amplitude and duration to said sensing electrode in contact with said solution in order to remove contaminants from said sensing electrode to provide a substantially contaminant-free electrode;
applying a plating signal of an amplitude and duration to said electrode, such that a portion of said metal ions from said solution form a plating on the surface of said electrode to form a plated electrode, and such that a portion of said organic addition agent is absorbed on said electrode surface;
applying a stripping signal of an amplitude and duration to said plated electrode, such that said plating on said surface of said plated electrode is removed, and further such that a stripping signal response current is produced, said stripping signal response current having signal characteristics responsive to said organic addition agent absorbed on said electrode surface; and
monitoring said signal characteristics of said stripping response current;
wherein variations in said stripping response current characteristics provide an accurate indication of the concentration level of said organic addition agent.
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Accused Products
Abstract
A method of selectively monitoring particular trace constituents within a plating bath containing multiple trace constituents. The method provides improved selectivity over known voltammetric techniques for certain plating baths and trace constituents. The method involves applying a brief voltammetric plating signal to a pretreated electrode positioned within the plating bath solution, applying a rapid stripping signal to the plated electrode, and monitoring the resultant stripping signal response current. The characteristics of the stripping signal response current indicate the particular trace constituent concentration level. The method complements and is easily integrated with known voltammetric techniques and equipment, and thus improves the efficiency and versatility of existing plating bath analysis systems.
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Citations
11 Claims
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1. A method of selectively monitoring the concentration of an organic addition agent present in a plating bath solution containing multiple trace constituents and metal ions wherein said organic addition agent is more rapidly absorbed than said trace constituents, said method comprising the steps of:
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providing at least one sensing electrode in contact with said solution; applying a pretreatment signal of an amplitude and duration to said sensing electrode in contact with said solution in order to remove contaminants from said sensing electrode to provide a substantially contaminant-free electrode; applying a plating signal of an amplitude and duration to said electrode, such that a portion of said metal ions from said solution form a plating on the surface of said electrode to form a plated electrode, and such that a portion of said organic addition agent is absorbed on said electrode surface; applying a stripping signal of an amplitude and duration to said plated electrode, such that said plating on said surface of said plated electrode is removed, and further such that a stripping signal response current is produced, said stripping signal response current having signal characteristics responsive to said organic addition agent absorbed on said electrode surface; and monitoring said signal characteristics of said stripping response current; wherein variations in said stripping response current characteristics provide an accurate indication of the concentration level of said organic addition agent. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification