Patent US4957541A successfully refreshed from Google Patents.
US4957541A
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US
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Capacitor grade tantalum powder
Assignee: Nrc Inc
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Filing: 1988-11-01
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Granted: 1990-09-18
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Expires: 2008-11-01
Abstract
Abstract Tantalum powders of capacitor grade are provided, containing interacting silicon and phosphorous dopants to effect low D.C. leakage of electrolytic capacitors having anodes made from such powders, with anodic formation at low temperatures (40°-60° C.), consistent with high capacitance.
Inventors
- 👤 Terrance B. Tripp
- 👤 Richard W. Hildreth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:54
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/052; H01G9/0525; B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
74 words
Improved capacitor grade tantalum powder which can be anodically formed to a low leakage product at formation temperatures selected substantially throughout the range 40°-90° C., comprising a content of silicon and phosphorous in combined concentration effecting a specific D.C. leakage (L/CV) of such powder of less than 0.5 nanoamperes per microfarad-volt and high specific capacitance (CV/g) in excess of 15,000 cv/gm in anodized pellets as made therefrom and sintered at 1,400° C. or higher.
Claim 2
Dependent Claim
74 words
Improved capacitor grade tantalum powder which can be anodically formed to a low leakage product at formation temperatures selected substantially throughout the range 40°-90° C., comprising a content of silicon and phosphorous in combined concentration effecting a specific D.C. leakage (L/CV) of such powder of less than 0.5 nanoamperes per microfarad-volt and high specific capacitance (CV/g) in excess of 15,000 cv/gm in anodized pellets as made therefrom and sintered at 1,400° C. or higher.
Claim 3
Dependent Claim
27 words
Tantalum powder in accordance with claim 1 wherein the silicon content is 50-1,000 ppm relative to tantalum and the phosphorous content is 10-300 ppm relative to tantalum.
Claim 4
Dependent Claim
12 words
The tantalum powder of claim 1 as formed into an agglomerated powder.
Claim 5
Dependent Claim
24 words
Tantalum powder in accordance with claim 2 wherein the silicon content is 100-500 ppm and the phosphorous content is 20-80 ppm relative to tantalum.
Claim 6
Dependent Claim
15 words
An anodic pellet made of a sintered mass of the agglomerated powder of claim 3.
Claim 7
Dependent Claim
16 words
The pellet of claim 5 as anodically formed at a temperature in the range 40°-60° C.
Claim 8
Dependent Claim
12 words
The pellet of claim 6 as formed in a dilute mineral acid.
References Cited (Backward Citations)
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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) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |