Abstract A pair of relatively inert metal electrodes 14 and 16 are immersed in a metal processing solution 10. The metal processing solution 10 is of the type that oxidizes a metal dissimilar from that of the electrodes from the elemental state to the ionic state. A predetermined potential is applied for a predetermined time across the electrodes to create a direct current through the solution, thereby plating a determinable quantity of the metal ionic species on one of the electrodes as a metal. After the potential is removed from the electrodes, the elapsed time required for essentially all of the metal to be reoxidized to the ionic state by the processing solution is measured. Since the plated metal is dissimilar from that of the electrode, a galvanic cell is formed. Thus, the elapsed time can be measured, for example, by coupling an external load in series with the two electrodes and noting the elapsed time during which a current flows through the load. The elapsed time thus measured provides a direct indication of the etching or stripping rate of the solution.
A method for providing an indication of the relative etching rate of a partially depleted oxidizing metal processing solution, said solution being partially depleted as a result of spontaneously oxidizing a metal to a dissolved metal ionic species, comprising the steps of: (a) immersing in said solution first and second spaced electrodes each composed of a metal relatively inert with respect to said solution; (b) applying a predetermined potential for a predetermined time across said electrodes to create a direct current through said solution between said electrodes to plate a determinable quantity of said metal ionic species as a metal plating on one of said electrodes; (c) thereafter allowing said solution to oxidize said metal plating back to said ionic species without applying a potential to said electrodes; and (d) measuring the elapsed time required for substantially all of said metal plating on said one electrode to be oxidized back to said ionic species.
Claim 2
Independent Claim
154 words
A method for providing an indication of the relative etching rate of a partially depleted oxidizing metal processing solution, said solution being partially depleted as a result of spontaneously oxidizing a metal to a dissolved metal ionic species, comprising the steps of: (a) immersing in said solution first and second spaced electrodes each composed of a metal relatively inert with respect to said solution; (b) applying a predetermined potential for a predetermined time across said electrodes to create a direct current through said solution between said electrodes to plate a determinable quantity of said metal ionic species as a metal plating on one of said electrodes; (c) thereafter allowing said solution to oxidize said metal plating back to said ionic species without applying a potential to said electrodes; and (d) measuring the elapsed time required for substantially all of said metal plating on said one electrode to be oxidized back to said ionic species.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said solution is a metal etching solution.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said solution is a metal stripping solution.
Claim 5
Dependent Claim
10 words
The method of claim 1 wherein said electrodes are platinum.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein steps (b) and (c) are conducted at substantially the same temperature.
Claim 7
Dependent Claim
66 words
The method of claim 1 wherein said elapsed time is measured by coupling an electrical load external to said solution across said electrodes at the end of said predetermined time, monitoring the current flow through said load, and measuring the elapsed time from the point when the load is coupled to said electrodes to the point at which current substantially ceases to flow through said load.