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US4674440A
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Apparatus for automatically replenishing an electroless plating bath
Assignee: Shipley Co Inc
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Filing: 1985-06-26
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Granted: 1987-06-23
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Expires: 2005-06-26
Abstract
Abstract An apparatus for maintaining the consumable components of an electroless plating solution at predetermined concentration in a plating tank containing the plating solution while workpieces are being processed in the tank. The apparatus measures the concentrations of the consumable components in a sample stream of the electroless plating solution and based on these measurements, meters the required amounts of the components into the plating solution. A portion of the apparatus provides for the introduction of plating solution poison into the sample stream to prevent autocatalytic decomposition and deposition of the plating metal, e.g., copper, onto to the walls and sensors of the apparatus.
Inventors
- 👤 William J. Cardin
- 👤 Michael Gulla
- 👤 Charles L. Newton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:04
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1617; C23C18/1633; C23C18/1675; C23C18/1683
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
274 words
Apparatus for maintaining the consumable components of an electroless plating solution at predetermined concentration in a plating tank containing said plating solution while workpieces are being processed in the tank, said consumable components comprising plating metal ions, pH adjustor and reducing agent, said apparatus comprising in combination: means for withdrawing a sample stream of plating solution at a predetermined rate from the plating tank and passing the same through a sequence of analyzing stations to a point of discharge; a first station consisting of means for analyzing the metal ion content of the sample stream and means operatively connected to and actuated by said metal ion analyzng means to meter plating metal ions to said electroless plating solution so as to replenish said solution with said ions; means for introducing into said sample stream a source of plating solution poison in an amount capable of preventing metal from plating from said solution, said means being located after said first station; a second station located after said means for introducing poison into said sample stream consisting of a pH analyzing station having means for measuring the pH of the sample stream, and means operatively connected to and actuated by said pH measuring means to meter pH adjustor to said electroless plating solution so as to replenish said solution with said adjustor; and a third station consisting of a reducing agent analyzing station having means for measuring the concentration of reducing agent, and means operatively connected to and actuated by said means for measuring reducing agent concentration to meter reducing agent to said electroless plating solution so as to replenish said solution with said reducing agent.
Claim 2
Dependent Claim
274 words
Apparatus for maintaining the consumable components of an electroless plating solution at predetermined concentration in a plating tank containing said plating solution while workpieces are being processed in the tank, said consumable components comprising plating metal ions, pH adjustor and reducing agent, said apparatus comprising in combination: means for withdrawing a sample stream of plating solution at a predetermined rate from the plating tank and passing the same through a sequence of analyzing stations to a point of discharge; a first station consisting of means for analyzing the metal ion content of the sample stream and means operatively connected to and actuated by said metal ion analyzng means to meter plating metal ions to said electroless plating solution so as to replenish said solution with said ions; means for introducing into said sample stream a source of plating solution poison in an amount capable of preventing metal from plating from said solution, said means being located after said first station; a second station located after said means for introducing poison into said sample stream consisting of a pH analyzing station having means for measuring the pH of the sample stream, and means operatively connected to and actuated by said pH measuring means to meter pH adjustor to said electroless plating solution so as to replenish said solution with said adjustor; and a third station consisting of a reducing agent analyzing station having means for measuring the concentration of reducing agent, and means operatively connected to and actuated by said means for measuring reducing agent concentration to meter reducing agent to said electroless plating solution so as to replenish said solution with said reducing agent.
Claim 3
Dependent Claim
16 words
Apparatus as defined in claim 1 where the plating solution is an electroless copper plating solution.
Claim 4
Dependent Claim
52 words
Apparatus as defined in claim 2, further including a source of aqueous sulfite solution and a source of aqueous acid solution, each of standardized molar concentration, and means for mixing said solutions into said sample stream at a constant predetermined rate, downstream of said second station and upstream of said third station.
Claim 5
Dependent Claim
45 words
The apparatus of claim 3 where said means for measuring the concentration of reducing agent comprises a second pH analyzing station having means for measuring the pH of the sample stream downstream of the point of introduction of the sulfite solution and the acid solution.
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) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |