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US4565575A
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US
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Apparatus and method for automatically maintaining an electroless plating bath
Assignee: Shipley Co Inc
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Filing: 1984-11-02
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Granted: 1986-01-21
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Expires: 2004-11-02
Abstract
Abstract A controller for measuring the concentration of consumable ingredients in a plating solution characterized by the use of a plating poison introduced into the analysate stream to prevent autocatalytic decomposition and deposition of copper onto the walls and sensors of the controller.
Inventors
- 👤 William J. Cardin
- 👤 Michael Gulla
- 👤 Charles L. Newton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:19
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1633; C23C18/1675; C23C18/1683; C23C18/1617; C23C18/31; C23C18/32; C23C18/34; C23C18/36; C23C18/38; C23C18/40; C23C18/405
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
104 words
In a method for automatically maintaining consumable components of an electroless metal plating solution at predetermined concentration in a plating tank while workpieces are being processed in the tank comprising the steps of: withdrawing a sample stream of the plating solution from the tank at a predetermined constant rate and passing the sample stream through a sequence of analyzing stations to a point of discharge; and subjecting the stream to analysis of the consumable components of the plating solution; the improvement comprising introducing a plating solution poison capable of inhibiting the plating of metal from solution into the sample stream at a predetermined rate.
Claim 2
Dependent Claim
104 words
In a method for automatically maintaining consumable components of an electroless metal plating solution at predetermined concentration in a plating tank while workpieces are being processed in the tank comprising the steps of: withdrawing a sample stream of the plating solution from the tank at a predetermined constant rate and passing the sample stream through a sequence of analyzing stations to a point of discharge; and subjecting the stream to analysis of the consumable components of the plating solution; the improvement comprising introducing a plating solution poison capable of inhibiting the plating of metal from solution into the sample stream at a predetermined rate.
Claim 3
Dependent Claim
33 words
The method of claim 1 where said plating solution is an aqueous electroless copper plating solution comprising copper ions, alkali metal hydroxide and formaldehyde or a formaldehyde derivative as the consumable components thereof.
Claim 4
Dependent Claim
28 words
The method or claim 1 where said plating solution is an aqueous electroless nickel plating solution comprising nickel ions, pH adjustor and hypophosphite as the consumable components thereof.
Claim 5
Dependent Claim
13 words
The method of claim 1 where the plating poison is a sulfur compound.
Claim 6
Dependent Claim
11 words
The method of claim 3 where the sulfur compound is thiourea.
Claim 7
Dependent Claim
158 words
The method of claim 2 where the subsequent analysis of the sample stream comprises: subjecting the stream to means for analyzing the copper ion concentration and automatically feeding an aqueous solution of copper ions replenisher solution from a source thereof into the plating tank whenever the analysis reading is below a predetermined level; subjecting the stream to analysis at a first pH station and automatically feeding an aqueous hydroxide replenisher solution from a source thereof into the plating tank whenever the analysis reading is below a predetermined level; introducing into the sample an aqueous sulfite solution of standardized molarity at a constant feed rate, and introducing into the sample an acid solution of standardized molarity, both at a constant feed rate, and subjecting the sample stream to a second pH station, and then automatically feeding an aqueous formaldehyde replenisher solution from a source thereof into the plating tank whenever said second pH reading is below a predetermined level.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-20 | 1989-07-22 | 1990-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-20 | 1993-07-22 | 1994-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-20 | 1997-07-22 | 1998-01-21 | $7700.00 | Window Closed / Lapsed |