US4016308A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Humidity sensor, material therefor and method
Assignee: Plessey Inc
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Filing: 1975-04-09
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Granted: 1977-04-05
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Expires: 1995-04-09
Abstract
Abstract A novel humidity sensor printed and fired on a dielectric substrate comprising an interdigitated pattern of a conductive precious metal with cobalt oxide as the only binder. Sensors according to the invention may be employed as hermeticity detectors in semiconductor packages.
Inventors
- 👤 Lawrence E. Frazee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 04:18
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/06; H01C17/065; H01C17/06506; H01C17/06513; H01C17/06553; G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
100 words
The method of making a humidity sensor comprising: forming a screen-printable paste including, on a dry basis, at least 2 wt. % of finely divided cobalt oxide powder and a major proportion of a finely divided precious metal powder plus an organic vehicle; printing a pattern of said material onto a ceramic substrate in the form of interdigitated fingers; drying said pattern; and firing said pattern at a temperature in the range of 1350° to 1550° C. for about 5 to 15 minutes, said oxide diffusing out from printed pattern areas to form a continuous hygroscopic film between said fingers.
Claim 2
Independent Claim
100 words
The method of making a humidity sensor comprising: forming a screen-printable paste including, on a dry basis, at least 2 wt. % of finely divided cobalt oxide powder and a major proportion of a finely divided precious metal powder plus an organic vehicle; printing a pattern of said material onto a ceramic substrate in the form of interdigitated fingers; drying said pattern; and firing said pattern at a temperature in the range of 1350° to 1550° C. for about 5 to 15 minutes, said oxide diffusing out from printed pattern areas to form a continuous hygroscopic film between said fingers.
Claim 3
Dependent Claim
32 words
The method as claimed in claim 1, wherein said paste comprises on a dry basis 2 to 20 wt. pct. cobalt oxide powder and 80 to 98 wt. pct. precious metal powder.
Claim 4
Dependent Claim
20 words
The method as claimed in claim 1, wherein the particle size of said powders is no more than 200 mesh.
Claim 5
Dependent Claim
39 words
The method as claimed in claim 1, wherein said precious metal powder has a melting point above the firing temperature and is selected from the group consisting of gold alloys, platinum, palladium and mixtures and alloys of these metals.
Claim 6
Dependent Claim
21 words
The method as claimed in claim 1, wherein said pattern additionally comprises an integral bonding pad printed with each said electrode.
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) | 1980-04-04 | 1980-10-04 | 1981-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-04 | 1984-10-04 | 1985-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-04 | 1988-10-04 | 1989-04-05 | $7700.00 | Window Closed / Lapsed |