Patent US4707378A successfully refreshed from Google Patents.
US4707378A
Expired / Lapsed
US
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Method and apparatus for controlling the organic contamination level in an electroless plating bath
Assignee: International Business Machines Corp
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Filing: 1986-07-11
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Granted: 1987-11-17
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Expires: 2006-07-11
Abstract
Abstract An electroless plating bath is selectively cleaned of organic contaminants. The organic contaminants are detected by measuring the capacitance between a working electrode and counter electrode with a potentiostat. The capacitance measurements are used to indicate the level of organic contaminants. Exposure of the dummy plating surface in the electroless plating bath is controlled such that the exposed surface is directly proportional to the detected level of organic contaminants.
Inventors
- 👤 Donald G. McBride
- 👤 Robert G. Rickert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:13
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1633; C23C18/1675; C23C18/1683; H; H05; H05K; H05K3/00; H05K3/10; H05K3/18; H05K3/181; H05K3/187
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
99 words
A method for controlling contaminants in an electroless plating bath comprising: measuring the complex impedance between a potentiostat working electrode and counter electrode immersed in said electroless plating bath; determining from said complex impedance a capacitive reactance and double layer capacitance of said bath; and exposing a dummy plating panel in said plating bath such that the exposed area of said dummy plating panel varies as said double layer capacitance level varies, whereby said dummy plating panel exposed to said electroless plating bath will plate out contaminants in said bath, maintaining said contaminant level at a predetermined minimum level.
Claim 2
Independent Claim
99 words
A method for controlling contaminants in an electroless plating bath comprising: measuring the complex impedance between a potentiostat working electrode and counter electrode immersed in said electroless plating bath; determining from said complex impedance a capacitive reactance and double layer capacitance of said bath; and exposing a dummy plating panel in said plating bath such that the exposed area of said dummy plating panel varies as said double layer capacitance level varies, whereby said dummy plating panel exposed to said electroless plating bath will plate out contaminants in said bath, maintaining said contaminant level at a predetermined minimum level.
Claim 3
Dependent Claim
32 words
The method of claim 1 wherein said exposing step will insert a maximum surface area of said dummy plating panel into said bath until a desired double layer capacitance level is produced.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein said exposed surface area of said dummy panel is reduced once said desired double layer capacitance level is reached.
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said dummy plating panel is advanced in steps during periodical time intervals to reach a desired surface exposure.
Claim 6
Dependent Claim
15 words
The method of claim 1 further comprising recording at periodic intervals said double layer capacitance.
Claim 7
Independent Claim
181 words
An apparatus for controlling for controlling organic contamination levels in an electroless plating bath comprising: a potentiostat having a working electrode and counter electrode disposed in said electroless plating bath; said potentiostat providing an AC voltage between said electrode for measuring the complex impedance of said bath; a dummy panel providing a surface area for plating out organic contaminants in said electroless plating bath; a dummy panel support for raising and lowering said dummy panel in said electroless plating bath; motor drive positioner for controlling said dummy panel support, whereby the amount of surface area of said dummy panel exposed to said bath is controlled; and, a computer controller connected to said potentiostat and to said motor drive assembly, said computer controller programmed to receive said potentiostat impedance measurements, and determine from said measurements a capacitance measurement which correlates to a contaminant level of said bath; said computer being further programmed to control said positioner to vary the amount of surface area of said dummy panel exposed in said electroless plating bath to reduce the amount of contaminants in said bath.
Claim 8
Independent Claim
181 words
An apparatus for controlling for controlling organic contamination levels in an electroless plating bath comprising: a potentiostat having a working electrode and counter electrode disposed in said electroless plating bath; said potentiostat providing an AC voltage between said electrode for measuring the complex impedance of said bath; a dummy panel providing a surface area for plating out organic contaminants in said electroless plating bath; a dummy panel support for raising and lowering said dummy panel in said electroless plating bath; motor drive positioner for controlling said dummy panel support, whereby the amount of surface area of said dummy panel exposed to said bath is controlled; and, a computer controller connected to said potentiostat and to said motor drive assembly, said computer controller programmed to receive said potentiostat impedance measurements, and determine from said measurements a capacitance measurement which correlates to a contaminant level of said bath; said computer being further programmed to control said positioner to vary the amount of surface area of said dummy panel exposed in said electroless plating bath to reduce the amount of contaminants in said bath.
Claim 9
Dependent Claim
18 words
The apparatus of claim 2 wherein said computer is further programmed to print said capacitance measurements over time.
Claim 10
Dependent Claim
39 words
The apparatus of claim 6 wherein said computer controller commands said positioner to increase said dummy panel surface area exposed in said electroless plating bath to a maximum exposure level until a desired double layer capacitance level is achieved.
Claim 11
Dependent Claim
30 words
The apparatus of claim 8 wherein said computer controller reduces said dummy panel surface exposure to said bath to maintain said measured capacitance at said desired double layer capacitance level.
Claim 12
Dependent Claim
19 words
The apparatus of claim 9 wherein said dummy panel exposure into said bath is stepwise changed in periodic intervals.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-16 | 1991-05-18 | 1991-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-16 | 1995-05-18 | 1995-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-16 | 1999-05-18 | 1999-11-17 | $7700.00 | Window Closed / Lapsed |