US4568384A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making Ag/Pd electroding powder
Assignee: MRA Laboratories Inc
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Filing: 1985-01-18
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Granted: 1986-02-04
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Expires: 2005-01-18
Abstract
Abstract Pure silver and palladium powders are thoroughly mixed and dispersed by ball milling in a solution of a surfactant in a liquid vehicle. After drying and granulating, the resulting powder was heated to 500° C., first to form an Ag/Pd alloy powder and then to cause palladium to precipitate from the interior of the alloy particles, to form a protective barrier of PdO on the alloy particle surfaces and to alter the alloy to 90Ag/10Pd. This powder, when used to make a buried electrode in a ceramic capacitor changes dimensions very little up to 500° C. in the early stage of sintering the ceramic below which temperature the ceramic is weakest and most subject to cleaving.
Inventors
- 👤 Galeb H. Maher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:05
CPC Classifications
H; H01; H01G; H01G4/00; H01G4/002; H01G4/005; H01G4/008; C; C22; C22C; C22C32/00; C22C32/001; C22C32/0015; C22C32/0021; Y; Y10; Y10T; Y10T29/00; Y10T29/43; Y10T29/435
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
80 words
A method for making a metal electroding powder for use in making monolithic ceramic capacitors comprising heating in air at about 500° C. a powder made up of particles of a silver-palladium alloy of less than 90% by weight silver to oxidize a portion of said palladium from said alloy to form a fine palladium oxide at the surfaces of said particles and to render said alloy more silver rich and having a composition of 90 Ag/10 Pd by weight.
Claim 2
Independent Claim
80 words
A method for making a metal electroding powder for use in making monolithic ceramic capacitors comprising heating in air at about 500° C. a powder made up of particles of a silver-palladium alloy of less than 90% by weight silver to oxidize a portion of said palladium from said alloy to form a fine palladium oxide at the surfaces of said particles and to render said alloy more silver rich and having a composition of 90 Ag/10 Pd by weight.
Claim 3
Dependent Claim
22 words
The method of claim 1 additionally comprising mixing said oxidized alloy powder with a liquid organic vehicle to form an electroding paste.
Claim 4
Dependent Claim
47 words
The method of claim 1 additionally comprising prior to said heating: mixing a silver powder with a palladium powder and thoroughly dispersing said two metal powders to form a homogenous two-metal-powder mixture; and preheating said mixture up to about 300° C. to form said silver-palladium alloy powder.
Claim 5
Dependent Claim
22 words
The method of claim 3 wherein the surface area of said silver powder is substantially less than that of said palladium powder.
Claim 6
Dependent Claim
36 words
The method of claim 4 wherein the surface area of said silver powder is less than 6 M 2 /gm and the surface area of said palladium powder is between 8 and 12 M 2 /gm.
Claim 7
Dependent Claim
28 words
The method of claim 5 additionally comprising comminuting said alloyed powder after said further heating until the powder surface area is from 0.5 to 5.0 M 2 /gm.
Claim 8
Dependent Claim
34 words
The method of claim 3 wherein said dispersing is accomplished by milling said silver and palladium powders in a liquid vehicle containing a dissolved cationic dispersant that begins to disintegrate at above 350° C.
Claim 9
Dependent Claim
23 words
The method of claim 3 wherein the ratio by weight of said silver powder to said palladium powder is between 30/70 to 90/10.
Claim 10
Independent Claim
141 words
A method for making a monolithic ceramic capacitor comprising: (a) making an electroding powder by heating in air a silver-palladium alloy powder of less than 90% by weight silver at about 500° C. to oxidize a portion of said palladium to form a fine palladium oxide at the surfaces of the particles of said alloy powder and to render said alloy more silver rich and having a composition of about 90 Ag/10 Pd by weight; (b) forming a plurality of layers of a green ceramic composition comprising a mixture of a high-firing-temperature ceramic powder and a low-melting-temperature sintering flux; (c) depositing a layer of said heated silver-palladium powder on each of said green ceramic layers; (d) stacking said green ceramic layers to form a green monolithic ceramic capacitor body; and (e) sintering said green ceramic body at less than 1200° C.
Claim 11
Independent Claim
141 words
A method for making a monolithic ceramic capacitor comprising: (a) making an electroding powder by heating in air a silver-palladium alloy powder of less than 90% by weight silver at about 500° C. to oxidize a portion of said palladium to form a fine palladium oxide at the surfaces of the particles of said alloy powder and to render said alloy more silver rich and having a composition of about 90 Ag/10 Pd by weight; (b) forming a plurality of layers of a green ceramic composition comprising a mixture of a high-firing-temperature ceramic powder and a low-melting-temperature sintering flux; (c) depositing a layer of said heated silver-palladium powder on each of said green ceramic layers; (d) stacking said green ceramic layers to form a green monolithic ceramic capacitor body; and (e) sintering said green ceramic body at less than 1200° C.
References Cited (Backward Citations)
US4324750A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |