US5085720A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for reducing shrinkage during firing of green ceramic bodies
Assignee: EIDP Inc
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Filing: 1991-04-29
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Granted: 1992-02-04
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Expires: 2011-04-29
Abstract
Abstract A method for reducing X-Y shrinkage during firing of green ceramic bodies in which a release layer, which becomes porous during firing, is placed upon the ceramic body and the assemblage is fired while maintaining pressure on the assemblage normal to the body surface.
Inventors
- 👤 Kurt R. Mikeska
- 👤 Daniel T. Schaefer
- 👤 Richard H. Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:55
CPC Classifications
H; H10; H10W; H10W99/00; C; C04; C04B; C04B35/00; C04B35/622; C04B35/626; C04B35/63; C04B35/6303; C04B35/632; C04B35/634; C04B35/64
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
197 words
A method for reducing X-Y shrinkage during firing of a green ceramic body comprising the sequential steps of a. Providing a green ceramic body comprising an admixture of finely divided particles of ceramic solids and sinterable inorganic binder dispersed in a volatilizable solid polymeric binder; b. Applying to a surface of the green ceramic body a flexible release layer comprising finely divided particles of non-metallic inorganic solids dispersed in volatilizable organic medium comprising at least 10% by volume, basis non-metallic inorganic solids, of volatilizable polymeric binder, the Penetration of the sinterable inorganic binder being no more than 50 μm; c. While maintaining unidirectional pressure normally to the exposed surface of the release layer, firing the assemblage at a temperature and for a time sufficient to effect volatilization of the polymeric binders from both the green tape and the release layer, sintering of the inorganic binder in the green tape without incurring radial bulk flow of the sintered tape, and the formation of interconnected porosity in the release layer; d. Cooling the fired assemblage; e. Releasing the pressure from the cooled assemblage; and f. Removing the porous release layer from the surface of the sintered ceramic green tape.
Claim 2
Independent Claim
197 words
A method for reducing X-Y shrinkage during firing of a green ceramic body comprising the sequential steps of a. Providing a green ceramic body comprising an admixture of finely divided particles of ceramic solids and sinterable inorganic binder dispersed in a volatilizable solid polymeric binder; b. Applying to a surface of the green ceramic body a flexible release layer comprising finely divided particles of non-metallic inorganic solids dispersed in volatilizable organic medium comprising at least 10% by volume, basis non-metallic inorganic solids, of volatilizable polymeric binder, the Penetration of the sinterable inorganic binder being no more than 50 μm; c. While maintaining unidirectional pressure normally to the exposed surface of the release layer, firing the assemblage at a temperature and for a time sufficient to effect volatilization of the polymeric binders from both the green tape and the release layer, sintering of the inorganic binder in the green tape without incurring radial bulk flow of the sintered tape, and the formation of interconnected porosity in the release layer; d. Cooling the fired assemblage; e. Releasing the pressure from the cooled assemblage; and f. Removing the porous release layer from the surface of the sintered ceramic green tape.
Claim 3
Dependent Claim
38 words
The method of claim 1 in which the sintering temperature of the non-metallic inorganic solids in the release layer is at least 50° C. higher than the sintering temperature of the inorganic binder in the green ceramic body.
Claim 4
Dependent Claim
18 words
The method of claim 1 in which the non-metallic inorganic solids in the release layer are ceramic solids.
Claim 5
Dependent Claim
20 words
The method of claim 1 in which the green ceramic body is one or more layers of ceramic green tape.
Claim 6
Dependent Claim
30 words
The method of claim 4 in which the ceramic solids in the green tape are selected from Al 2 O 3 , SiO 2 , and mixtures and precursors thereof.
Claim 7
Dependent Claim
34 words
The method of claim 3 in which the ceramic solids in the release layer are selected from Al 2 O 3 , CeO 2 , SnO 2 , MgO, ZrO 2 and mixtures thereof.
Claim 8
Dependent Claim
22 words
The method of claim 3 in which the ceramic solids in both the green ceramic body and the release layer are alumina.
Claim 9
Dependent Claim
22 words
The method of claim 2 in which the sintering temperature of the inorganic binder in the green ceramic tape is 600°-900° C.
Claim 10
Dependent Claim
15 words
The method of claim 1 in which the inorganic binder is an amorphous crystallizable glass.
Claim 11
Dependent Claim
15 words
The method of claim 1 in which the inorganic binder is an amorphous vitrifiable glass.
Claim 12
Dependent Claim
45 words
The method of claim 4 in which the ceramic solids and inorganic binder contents of the green tape constitute 30-70% by volume of the ceramic green tape and the non-metallic inorganic solids content of the release layer constitutes 10-50% by volume of the release layer.
Claim 13
Dependent Claim
41 words
The method of claim 4 in which the average particle size of the solids in the green tape and release layer is 1-20 microns with less than 30% by volume of such particles having a particle size less than 1 micron.
Claim 14
Dependent Claim
27 words
The method of claim 1 in which the contact angle of the inorganic binder on the non-metallic solids of the release layer is greater than 60 degrees.
Claim 15
Dependent Claim
20 words
The method of claim 1 in which the viscosity of the sinterable inorganic binder is at least 1×10 5 poise.
Claim 16
Dependent Claim
29 words
The method of claim 1 in which the interconnected pore volume of the fired release layer is at least 10% of the total volume of the fired release layer.
Claim 17
Dependent Claim
26 words
The method of claim 4 in which an exposed surface of the unfired green tape is laminated to a pre-fired planar ceramic substrate prior to firing.
Claim 18
Dependent Claim
24 words
The method of claim 16 in which an exposed surface of ceramic green tape is laminated to both sides of the planar ceramic substrate.
Claim 19
Dependent Claim
20 words
The method of claim 16 or 17 in which at least one surface of the subtrate contains a conductive pattern.
Claim 20
Dependent Claim
44 words
The method of claim 4 in which a thick film conductive pattern is applied to the fired tape after removal of the release layer and the pattern is fired to effect volatilization of the organic medium therefrom and sintering of the conductive solids therein.
Claim 21
Dependent Claim
22 words
The method of claim 19 in which the conductive material in the pattern is a noble metal or mixture or alloy thereof.
Claim 22
Dependent Claim
16 words
The method of claim 20 in which the noble metal is gold or a gold alloy.
Claim 23
Dependent Claim
19 words
The method of claim 19 in which the conductive material in the pattern is copper or a precursor thereof.
Claim 24
Dependent Claim
22 words
The method of claim 1 in which the unilateral pressure is first applied upon completion of the volatilization of the polymeric binders.
Claim 25
Dependent Claim
26 words
The method of claim 1 in which the unilateral pressure is first applied upon the onset of sintering of the inorganic binder in the green tape.
Claim 26
Dependent Claim
31 words
The method of claim 4 in which at least one layer of green tape has printed thereon an unfired pattern of thick film electrically functional paste and the assemblage is co-fired.
Claim 27
Dependent Claim
16 words
The method of claim 25 in which the thick film electrically functional paste is a resistor.
Claim 28
Dependent Claim
16 words
The method of claim 25 in which the thick film electrically functional paste is a conductor.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-03 | 1995-08-05 | 1996-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-03 | 1999-08-05 | 2000-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-03 | 2003-08-05 | 2004-02-04 | $7700.00 | Window Closed / Lapsed |