US3662458A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical contact for silicon carbide members
Assignee: Westinghouse Electric Corp
•
Filing: 1969-06-20
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Granted: 1972-05-16
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Expires: 1989-06-20
Abstract
Abstract Tantalum and gold alloy electrical contacts are applied to selected areas of a body of silicon carbide. An oxidized surface is first produced on the silicon carbide body and removed from those portions of the surface to which the alloy contact of the body is to be applied. A thin layer of aluminum is deposited on only the oxidized surface. Thin films of tantalum and gold are alternately deposited on the exposed surface of the silicon carbide. Any tantalum and gold deposited on the aluminum forms an alloy which is readily removed by an etchant which attacks tantalum-gold-aluminum intermetallics but will not attack the tantalum-gold alloy electrical contact of the body.
Inventors
- 👤 Napolean P Formigoni
- 👤 John S Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:00
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/60; H10D64/62; H10W; H10W20/00; H10W20/40; Y; Y10; Y10S; Y10S438/00; Y10S438/931
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
The process of claim 1 wherein the heat treating of the silicon carbide body with gold-tantalum layers present only on the selected areas is accomplished at a first elevated temperature of from 850* to 1,050* C. for a period of about 10 minutes and then heat treating the body at a second elevated temperature of from 1,500* to 1,700* C. for a period not exceeding about 15 seconds at the maximum temperature to alloy the tantalum, the gold, and the silicon carbide.
Claim 2
Dependent Claim
15 words
The process of claim 2 wherein the etchant is a saturated solution of sodium hydroxide.
Claim 3
Dependent Claim
43 words
The process of claim 3 including the process step prior to etching the silicon carbide body of heat treating the silicon carbide body at an elevated temperature of from 280* to 320* C. for a period of time of up to 16 hours.
Claim 4
Dependent Claim
14 words
The process of claim 4 wherein the heat treating is performed in a vacuum.
Claim 5
Dependent Claim
23 words
The process of claim 5 wherein the heat treating is carried out in a controlled atmosphere of a gas inert to the body.
Claim 6
Dependent Claim
68 words
The process of claim 2 wherein at least two layers of tantalum and two layers of gold are deposited on the selected areas of the silicon carbide body; the total thickness of the layers of tantalum and gold is from 1,000 to 10,000 A, the volume ratio of tantalum to gold is from about 1:5 to 1:15, and the thickness of the layer of aluminum is 10,000 A.
References Cited (Backward Citations)
US3492719A
Cited
US3516914A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |