Patent US5277724A successfully refreshed from Google Patents.
US5277724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of minimizing lateral shrinkage in a co-fired, ceramic-on-metal circuit board
Assignee: General Electric Co
•
Filing: 1991-12-18
•
Granted: 1994-01-11
•
Expires: 2011-12-18
Abstract
Abstract A method of fabricating a multi-layered, co-fired, ceramic-on-metal circuit board utilizes a bonding layer of glass. The glass has a coefficient of thermal expansion not greater than that of the metal base. The glass of the bonding layer has a softening point below that of the glass in the multi-layer ceramic so that the glass of the bonding layer flows and bonds to the metal to minimize the lateral shrinkage of the multi-layered ceramic.
Inventors
- 👤 Ashok N. Prabhu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:58
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/60; H10W70/67; H10W70/68; H10W70/6875; B; B32; B32B; B32B18/00; C; C03; C03C; C03C10/00; C03C10/0054; C04; C04B; C04B37/00; C04B37/02; C04B37/023; C04B37/025; H10W70/69; H10W70/692; C04B2235/00; C04B2235/65; C04B2235/656; C04B2235/6567; C04B2235/658; C04B2235/70; C04B2235/96; C04B2235/9607; C04B2235/9615; C04B2237/00; C04B2237/02; C04B2237/10; C04B2237/30; C04B2237/32; C04B2237/34; C04B2237/40; C04B2237/402; C04B2237/405; C04B2237/406; C04B2237/407; H10W70/682; H10W70/685; H10W90/00; H10W90/701; H10W90/751; H10W90/754
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
138 words
A method of making a co-fired, ceramic-on-metal circuit board comprising a multi-layered ceramic-on-metal base, said metal base having oppositely disposed major surfaces, said method including the steps of depositing a bonding layer of glass on one of said major surfaces of said metal base, said glass bonding layer having a coefficient of thermal expansion not greater than that of said base, providing a bisque fired or green multi-layered ceramic on said glass bonding layer wherein each layer of said multi-layered ceramic comprises a glass ceramic/filter composition, and co-firing said base, said glass bonding layer and said multi-layered ceramic to a temperature sufficient to achieve densification of said multi-layered ceramic and securely attach said multi-layered ceramic to said base, whereby the glass of said bonding layer flows and bonds to said multi-layered ceramic, thereby minimizing the lateral shrinkage thereof.
Claim 2
Independent Claim
138 words
A method of making a co-fired, ceramic-on-metal circuit board comprising a multi-layered ceramic-on-metal base, said metal base having oppositely disposed major surfaces, said method including the steps of depositing a bonding layer of glass on one of said major surfaces of said metal base, said glass bonding layer having a coefficient of thermal expansion not greater than that of said base, providing a bisque fired or green multi-layered ceramic on said glass bonding layer wherein each layer of said multi-layered ceramic comprises a glass ceramic/filter composition, and co-firing said base, said glass bonding layer and said multi-layered ceramic to a temperature sufficient to achieve densification of said multi-layered ceramic and securely attach said multi-layered ceramic to said base, whereby the glass of said bonding layer flows and bonds to said multi-layered ceramic, thereby minimizing the lateral shrinkage thereof.
Claim 3
Dependent Claim
38 words
The method as described in claim 1, wherein the glass of said bonding layer is heated to a temperature of about 450° C., to pre-flow the glass of the bonding layer, prior to providing said multi-layered ceramic thereon.
Claim 4
Dependent Claim
21 words
The method as described in claim 1, wherein said co-firing step is carried out at a temperature of about 900° C.
Claim 5
Dependent Claim
18 words
The method as described in claim 3, wherein said co-firing step is carried out in a nitrogen atmosphere.
Claim 6
Independent Claim
187 words
A method of minimizing lateral shrinkage in a co-fired, ceramic-on-metal circuit board comprising a multi-layered ceramic on a metal base, said metal base having oppositely disposed major surfaces, said method including the steps of depositing a bonding layer of glass on one of said major surfaces of said metal base, the glass of said bonding layer having a coefficient of thermal expansion not greater than that of said base, providing a bisque fired or green multi-layered ceramic on said bonding layer, each layer of said multi-layered ceramic comprising a glass-ceramic/filler composition having a coefficient of thermal expansion that closely matches that of said base and the glass of said bonding layer over a temperature range from room temperature to about 600° C., and co-firing said base, said bonding layer and said multi-layered ceramic to an elevated temperature sufficient to securely attach said multi-layered ceramic to said base, the glass of said bonding layer having a softening point below that of said multi-layered ceramic so that the glass of said bonding layer flows and bonds to the metal base while minimizing the lateral shrinkage of said multi-layered ceramic.
Claim 7
Independent Claim
187 words
A method of minimizing lateral shrinkage in a co-fired, ceramic-on-metal circuit board comprising a multi-layered ceramic on a metal base, said metal base having oppositely disposed major surfaces, said method including the steps of depositing a bonding layer of glass on one of said major surfaces of said metal base, the glass of said bonding layer having a coefficient of thermal expansion not greater than that of said base, providing a bisque fired or green multi-layered ceramic on said bonding layer, each layer of said multi-layered ceramic comprising a glass-ceramic/filler composition having a coefficient of thermal expansion that closely matches that of said base and the glass of said bonding layer over a temperature range from room temperature to about 600° C., and co-firing said base, said bonding layer and said multi-layered ceramic to an elevated temperature sufficient to securely attach said multi-layered ceramic to said base, the glass of said bonding layer having a softening point below that of said multi-layered ceramic so that the glass of said bonding layer flows and bonds to the metal base while minimizing the lateral shrinkage of said multi-layered ceramic.
Claim 8
Dependent Claim
38 words
The method as described in claim 5, wherein the glass of said bonding layer is heated to a temperature of about 450° C. to pre-flow said glass of said bonding layer, prior to providing said multi-layered ceramic thereon.
Claim 9
Dependent Claim
33 words
The method as described in claim 5, wherein said co-firing step is carried out at a temperature of about 900° to 930° C. for about 2 to 20 minutes, in a nitrogen atmosphere.
References Cited (Backward Citations)
US4291107A
Cited
US4801488A
Cited
US5044074A
Cited
US4952531A
Cited
US5043222A
Cited
US5047371A
Cited
US4930857A
Cited
US5041695A
Cited
US5013360A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-01-10 | 1997-07-12 | 1998-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-10 | 2001-07-12 | 2002-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-10 | 2005-07-12 | 2006-01-11 | $7700.00 | Window Closed / Lapsed |