US3754987A
Expired / Lapsed
US
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Method of producing areas of relatively high electrical resistivity in dielectric substrates
Assignee: Texas Instruments Inc
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Filing: 1971-06-04
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Granted: 1973-08-28
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Expires: 1991-06-04
Abstract
Abstract Areas of relatively high electrical resistivity in a dielectric substrate, such as doped barium titanate, may be produced by first forming a relatively porous substrate which may be handled without breaking, as by prefiring the substrate, masking selected portions of the substrate with a material such as a photoresist material which will vaporize during final firing of the substrate, contacting the substrate with a solution of a first reactant, immersing at least a portion of the substrate in a solution of a second reactant which will react with the first reactant to precipitate in situ in a portion of the substrate a transition metallic compound which is insoluble in the solutions and which is adapted to increase the electrical resistivity of the said portion of the substrate, and thereafter firing the sustrate at a temperature on the order of 1,300* - 1,450*C. to reduce the porosity of the substrate and to incorporate the insoluble compound into the lattice of selected portions of the substrate. The starting material may be a lanthanum doped barium titanate, for example, the solution of the first reactant may be an aqueous solution of a compound such as ammonium hydroxide, and the solution of the second reactant may be an aqueous solution of an iron compound such as ferric chloride which reacts with the ammonium hydroxide to precipitate in situ ferric hydroxide which, when fired, produces a high resistivity area.
Inventors
- 👤 A Purdes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:14
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/022; H01C7/023; H01C7/025; C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; H10; H10P; H10P95/00; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49082; Y10T29/49099
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
11 words
The method of claim 1 wherein said transition metal is iron.
Claim 2
Dependent Claim
11 words
The method of claim 1 wherein said transition metal is manganese.
Claim 3
Dependent Claim
11 words
The method of claim 1 wherein said transition metal is copper.
Claim 4
Dependent Claim
11 words
The method of claim 1 wherein said transition metal is vanadium.
Claim 5
Dependent Claim
11 words
The method of claim 1 wherein said transition metal is ruthenium.
Claim 6
Dependent Claim
11 words
The method of claim 1 wherein said transition metal is molybdenum.
Claim 7
Dependent Claim
34 words
The method of claim 1 wherein the masked portions of the substrate are masked with a material which is adapted to be vaporized and said material is vaporized from the substrate during firing thereof.
Claim 8
Independent Claim
186 words
The method of producing areas of relatively high electrical resistivity in selected portions of a doped barium titanate substrate comprising: forming a relatively porous doped barium titanate substrate by pressing the material to a theoretical density of less than 90 percent and prefiring the substrate at a temperature between approximately 1,000* - 1,300*C. so that it may be handled without breakage; masking selected portions of the substrate; contacting the substrate with a solution of a first reactant; saturating into at least a portion of the substrate a solution of a second reactant reactive with the first reactant comprising a soluble compound containing a transition metal which reacts with said first reactant to produce a transition metallic compound insoluble in said solutions and to precipitate in situ in a portion of the substrate the transition metallic compound which is adapted to increase the electrical resistivity of said portion of the substrate; and thereafter firing the substrate at a temperature between approximately 1,300* - 1,450*C. for less than one hour to reduce its porosity and to incorporate said insoluble transition metallic compound into the lattice of the substrate.
Claim 9
Dependent Claim
23 words
The method of claim 9 wherein said transition metal is selected from the group consisting of iron, manganese, copper, vanadium, ruthenium and molybdenum.
Claim 10
Dependent Claim
21 words
The method of claim 9 wherein said transition metal is selected from the group consisting of iron, manganese, copper and vanadium.
Claim 11
Independent Claim
194 words
The method of producing areas of relatively high electrical resistivity in selected portions of a doped titanate substrate comprising: providing a doped titanate substrate having a theoretical density of less than 90 percent and prefired at a temperature between approximately 1,100* - 1,300*C. so that it may be handled without breakage; masking selected portions of the substrate; saturating the substrate with a solution of a first reactant selected from the group consisting of soluble ammonium compounds, sodium hydroxide and potassium hydroxide; placing at least a portion of the substrate into a solution of a second reactant reactive with the first reactant comprising a soluble ferric compound which reacts with said first reactant to produce a ferRic compound insoluble in said solutions and to precipitate in situ in a portion of the substrate the ferric compound which is adapted to increase the electrical resistivity of said portion of the substrate; and firing the substrate at a temperature between approximately 1, 400* - 1,450*C. for approximately one hour to incorporate said insoluble ferric compound into the lattice of selected portions of the substrate and thereby increasing the electrical resistivity of said selected portions of the substrate.
Claim 12
Dependent Claim
34 words
The method of claim 12 wherein the masked portions of the substrate are masked with a material which is adapted to be vaporized, and said material is vaporized from the substrate during firing thereof.
Claim 13
Independent Claim
193 words
The method of producing areas of relatively high electrical resistivity in selected portions of a doped barium titante substrate comprising: forming a relatively porous doped barium titanate substrate by pressing the material to a theoretical density of less than 90 percent and prefiring the substrate at a temperature between approximately 1,000* - 1,300*C. so that it may be handled without breakage; masking selected portions of the substrate; saturating the substrate with a solution of a first reactant selected from the group consisting of soluble ammonium compounds, sodium hydroxide and potassium hydroxide; placing into at least a portion of the substrate a solution of a second reactant reactive with the first reactant comprising a soluble ferric compound which reacts with said first reactant to produce a ferric compound insoluble in said solutions and to precipitate in situ in a portion of the substrate the ferric compound which is adapted to increase the electrical resistivity of said portion of the substrate; and thereafter firing the substrate at a temperature between approximately 1,400*C - 1,450*C. for approximately one hour to reduce its porosity and to incorporate said insoluble ferric compound into the lattice of the substrate.
Claim 14
Dependent Claim
34 words
The method of claim 14 wherein the masked portions of the substrate are masked with a material which is adapted to be vaporized, and said material is vaporized from the substrate during said firing.
Claim 15
Dependent Claim
22 words
The method of claim 14 wherein the solution of said first reactant is an aqueous solution of a water soluble ammonium compound.
Claim 16
Dependent Claim
33 words
The method of claim 16 wherein the solution of said second reactant is an aqueous solution of a ferric compound which reacts with said ammonium compound to form a water insoluble ferric compound.
Claim 17
Independent Claim
202 words
The method of producing areas of relatively high electrical resisitivity in selected portions of a doped barium titanate substrate comprising: forming a relatively porous doped barium titanate substrate by pressing the material to a theoretical density of less than 90 percent and prefiring the substrate at a temperature between approximately 1,100* - 1,300*C. so that it may be handled without breakage; masking selected portions of said substrate with a material which is adapted to be vaporized; saturating the substrate with a solution of a first reactant selected from the group consisting of soluble ammonium compounds, sodium hydroxide and potassium hydroxide; immersing at least a portion of the substrate in a solution of a second reactant reactive with the first reactant comprising a soluble ferric compound which reacts with said first reactant to produce a ferric compound insoluble in said solutions and to precipitate in situ in a portion of the substrate the ferric compound which is adapted to increase the electrical resistivity of said portion of the substrate; and thereafter firing the substrate at a temperature between approximately 1,400* - 1,450*C. for approximately 1 hour to reduce its porosity and to incorporate said insoluble ferric compound into the lattice of the substrate.
Claim 18
Dependent Claim
19 words
The method of claim 18 wherein the solution of said first reactant is an aqueous solution of ammonium hydroxide.
Claim 19
Dependent Claim
42 words
The method of claim 19 wherein a relatively porous doped barium titanate substrate is formed by pressing doped barium titanate into a substrate of the desired shape under a pressure sufficient to reduce the porosity thereof no more than approximately 50 percent.
Claim 20
Dependent Claim
16 words
The method of claim 1 wherein the substrate is composed of barium titanate doped with lanthanum.
Claim 21
Dependent Claim
24 words
The method of claim 9 wherein the transition metal is manganese, the solution of said first reactant is an aqueous solution of ammonium hydroxide.
Claim 22
Dependent Claim
27 words
The method of claim 22 wherein the solution of said second reactant is an aqueous solution of manganese dichloride and the insoluble manganese compound is manganous hydroxide.
Claim 23
Dependent Claim
23 words
The method of claim 9 wherein the transition metal is copper, the solution of said first reactant is an aqueous solution of triethylamine.
Claim 24
Dependent Claim
27 words
The method of claim 24 wherein the solution of said second reactant is an aqueous solution of cupric nitrate and the insoluble cupric compound is cupric hydroxide.
Claim 25
Dependent Claim
30 words
The method of claim 9 wherein the substrate is doped with yttrium and the transition metal is vanadium, the solution of said first reactant is an aqueous solution of aniline.
Claim 26
Dependent Claim
19 words
The method of claim 26 wherein the solution of said second reactant is an aqueous solution of vanadium sulfate.
Claim 27
Independent Claim
193 words
The method of producing areas of relatively high electrical resistivity in selected portions of a doped titanate substrate comprising: forming a relatively porous doped titanate substrate by pressing the material to a theoretical density of less than 90 percent and prefiring the substrate at a temperature between approximately 1,000* - 1,300*C. so that it may be handled without breakage; masking selected portions of said substrate with a material which is adapted to be vaporized; saturating the substrate with a solution of a first reactant; immersing at least a portion of the substrate in a solution of a second reactant reactive with the first reactant, at least one of said first and second reactants comprising a soluble compound containing a transition metal which reacts with the other of said first and second reactant to produce a transition metallic compound insoluble in said solutions and to precipitate in situ in a portion of the substrate the transition metallic compound which is adapted to increase the electrical resistivity of said portion of the substrate; and thereafter firing the substrate to reduce its porosity and to incorporate said insoluble ferric compound into the lattice of the substrate.
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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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |