US3880971A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlling shrinkage caused by sintering of high alumina ceramic materials
Assignee: AT&T Inc
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Filing: 1973-12-26
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Granted: 1975-04-29
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Expires: 1993-12-26
Abstract
Abstract The shrinkage of a high alumina ceramic during sintering has been found to be related to the optical density of the green (unfired) material. Since shrinkage is dependent upon sintering conditions (time and temperature), measuring the optical density of the green material enables the proper selection of sintering conditions to achieve the desired shrinkage according to a predetermined relationship between optical density, shrinkage, time and temperature. The technique is expected to have particular utility in integrated circuit manufacture by enabling the accurate emplacement of ''''via'''' holes in high alumina ceramic substrates by punching the holes in the green substrate prior to sintering.
Inventors
- 👤 Georges Pierre Pantanelli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:16
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/622; C04B35/64
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
138 words
THE METHOD OF PRODUCING CERAMIC BODIES THE COMPONENTS OF WHICH COMPRISES AT LEAST 95 WEIGHT PERCENT AL2O3 CONTAINING AT LEAST A PAIR OF IDENTIFIABLE BENCHMARKS HAVING A REQUIRED SPACING COMPRISING PRODUCING AN UNFIRED CERAMIC BODY CONTAINING THE BENCHMARKS SPACED APART A DISTANCE GREATER THAN THE REQUIRED SPACING BY AN AMOUNT WITHIN THE RANGE OF POSSIBLE FIRING SHRINKAGE OF SAID CERAMIC AND THEN FIRING SAID CERAMIC BODY WHEREIN THE IMPROVEMENT COMPRISES MEASURING THE OPTICAL DENSITY OF SAID CERAMIC BODY PRIOR TO FIRING AND THEN CONDUCTING THE FIRING OF SAID CERAMIC BODY AT A TEMPERATURE AND FOR A TIME SHOWN BY PRIOR ASSEMBLED DATA CORRELATING OPTICAL DENSITY AND FIRING SHRINKAGE TO YEILD THE DEGREE OF FIRING SHRINKAGE WHICH WILL PRODUCE THE REQUIRED SPACING OF SAID BENCHMARKS IN A CERAMIC OF SIMILAR BASIC COMPOSITION PROCESSED AND MEASURED UNDER THE SAME CONDITIONS.
Claim 2
Independent Claim
138 words
THE METHOD OF PRODUCING CERAMIC BODIES THE COMPONENTS OF WHICH COMPRISES AT LEAST 95 WEIGHT PERCENT AL2O3 CONTAINING AT LEAST A PAIR OF IDENTIFIABLE BENCHMARKS HAVING A REQUIRED SPACING COMPRISING PRODUCING AN UNFIRED CERAMIC BODY CONTAINING THE BENCHMARKS SPACED APART A DISTANCE GREATER THAN THE REQUIRED SPACING BY AN AMOUNT WITHIN THE RANGE OF POSSIBLE FIRING SHRINKAGE OF SAID CERAMIC AND THEN FIRING SAID CERAMIC BODY WHEREIN THE IMPROVEMENT COMPRISES MEASURING THE OPTICAL DENSITY OF SAID CERAMIC BODY PRIOR TO FIRING AND THEN CONDUCTING THE FIRING OF SAID CERAMIC BODY AT A TEMPERATURE AND FOR A TIME SHOWN BY PRIOR ASSEMBLED DATA CORRELATING OPTICAL DENSITY AND FIRING SHRINKAGE TO YEILD THE DEGREE OF FIRING SHRINKAGE WHICH WILL PRODUCE THE REQUIRED SPACING OF SAID BENCHMARKS IN A CERAMIC OF SIMILAR BASIC COMPOSITION PROCESSED AND MEASURED UNDER THE SAME CONDITIONS.
Claim 3
Dependent Claim
25 words
The method of claim 1 in which the ceramic body is a ceramic sheet the components of which comprise at least 99 weight percent Al2O3.
Claim 4
Dependent Claim
30 words
sintering the green body at a time and temperature sufficient to achieve a desired shrinkage during sintering according to a predetermined empirical relationship between optical density, shrinkage, time and temperature.
Claim 5
Dependent Claim
30 words
sintering the green body at a time and temperature sufficient to achieve a desired shrinkage during sintering according to a predetermined empirical relationship between optical density, shrinkage, time and temperature.
Claim 6
Dependent Claim
15 words
The method of claim 2 in which said benchmarks are holes penetrating the ceramic sheet.
Claim 7
Dependent Claim
47 words
A process of producing fired ceramic sheets the components of which comprise at least 95 weight percent Al2O3 in which the optical density of the ceramic is measured before firing and then used as the basis for controlling the degree of shrinkage of said sheets upon firing.
Claim 8
Dependent Claim
47 words
A process of producing fired ceramic sheets the components of which comprise at least 95 weight percent Al2O3 in which the optical density of the ceramic is measured before firing and then used as the basis for controlling the degree of shrinkage of said sheets upon firing.
Claim 9
Dependent Claim
27 words
Method for gontrolling shrinkage caused by sintering a green body of a ceramic material the components of which comprise at least 95 weight percent Al2O3 characterized by:
Claim 10
Dependent Claim
27 words
Method for gontrolling shrinkage caused by sintering a green body of a ceramic material the components of which comprise at least 95 weight percent Al2O3 characterized by:
Claim 11
Dependent Claim
33 words
The method of claim 5 in which the sintering time is maintained within + or - 2 percent of a constant value, and the sintering temperature is varied to achieve the desired shrinkage.
Claim 12
Dependent Claim
25 words
The method of claim 5, wherein the white light is derived from a xenon light source, and the value of n1 is taken as 1.764.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |