Patent US4963414A successfully refreshed from Google Patents.
US4963414A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low thermal expansion, heat sinking substrate for electronic surface mount applications
Assignee: General Electric Co
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Filing: 1989-06-12
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Granted: 1990-10-16
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Expires: 2009-06-12
Abstract
Abstract The heat sinking substrate herein disclosed is comprised of a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bond together by coal tar pitch, the core being enclosed by two metallic face sheets having a coefficient of thermal expansion suited to the electronic packages it supports. The substrate is designed to be installed into a module with a printed wiring board on either side, the module being installed in parallel with other like modules into a chassis. The heat generated by the electronics is input over the face of the substrate and withdrawn by cooling in the walls of the chassis with which the substrates are in good thermal contact. The grain of the core is aligned for maximum thermal conduction along the path to the chassis walls. The substrate is of low weight, has a CTE matched to the supported electronic packages, high thermal conductance, and uses low cost materials.
Inventors
- 👤 Robert D. LeVasseur
- 👤 Stephen A. McKeown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:50
CPC Classifications
H; H05; H05K; H05K7/00; H05K7/14; H05K7/1401; H05K7/1402; H05K7/1404; H05K1/00; H05K1/02; H05K1/03; H05K1/05; H05K1/056; Y; Y10; Y10S; Y10S428/00; Y10S428/901; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/30; Y10T428/31504; Y10T428/31678; Y10T428/31692
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
65 words
A heat sinking substrate for surface mounted electronic device packages, said substrate comprising, in combination: A. a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bound together by pitch, said core having opposed, planar surfaces; and B. a metallic face sheet adhered to each planar surface, each face sheet having a coefficient of thermal of expansion suited to said packages.
Claim 2
Dependent Claim
65 words
A heat sinking substrate for surface mounted electronic device packages, said substrate comprising, in combination: A. a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bound together by pitch, said core having opposed, planar surfaces; and B. a metallic face sheet adhered to each planar surface, each face sheet having a coefficient of thermal of expansion suited to said packages.
Claim 3
Dependent Claim
36 words
The heat sinking substrate set forth in claim 1 wherein said core is adhered to said metallic face sheets by means of a fiber reinforced resin having a coefficient of thermal expansion suited to said packages.
Claim 4
Dependent Claim
27 words
The heat sinking substrate set forth in claim 2 wherein said core is adhered to said metallic face sheets by means of an aramid reinforced epoxy resin.
Claim 5
Dependent Claim
25 words
The heat sinking substrate set forth in claim 2 wherein said metallic face sheets are formed of bonded layers of copper, molybdenum and copper respectively.
Claim 6
Dependent Claim
62 words
The heat sinking substrate set forth in claim 4 wherein the copper sheets of said copper, molybdenum copper face sheets are oxidized to facilitate adhesion between said face sheets and said core and adhesion to the exposed copper sheets, and a pair of marginal metallic layers are provided at opposite ends of the exposed copper sheets for thermal conduction to a cooler.
Claim 7
Dependent Claim
18 words
The heat sinking substrate set forth in claim 5 wherein said pair of marginal metallic layers are nickel.
Claim 8
Dependent Claim
42 words
The heat sinking substrate set forth in claim 5 wherein the crystallites of said core are oriented for maximum thermal conductivity in a plane parallel to its surfaces and extending between said marginal metallic layers for improved thermal conduction to said cooler.
Claim 9
Dependent Claim
39 words
The heat sinking substrate set forth in claim 7 wherein said copper to molybdenum ratio is from 15 to 40 volume percent to achieve a CTE of approximately 6 to 7 ppm/° C., and said packages are ceramic packages.
Claim 10
Dependent Claim
42 words
The heat sinking substrate set forth in claim 8 wherein said core is approximately 8/10 of the volume of said substrate and said face sheets are approximately 2/10 of the volume of said substrate to achieve a low weight high strength design.
Claim 11
Dependent Claim
20 words
The combination set forth in claim 4 having in addition thereto a printed wiring board bonded to each face sheet.
Claim 12
Dependent Claim
29 words
The combination set forth in claim 10 wherein said printed wiring board is of an aramid reinforced epoxy resin having a coefficient of thermal expansion suited to said packages.
Claim 13
Dependent Claim
63 words
The combination set forth in claim 10 wherein the copper sheets of said copper, molybdenum copper face sheets are oxidized to facilitate adhesion between said face sheets and said core and adhesion between said printed wiring board and said substrate, and a pair of marginal metallic layers are provided at opposite ends of the exposed copper sheets for thermal connection to a cooler.
Claim 14
Dependent Claim
16 words
The combination set forth in claim 12 wherein said pair of marginal metallic layers are nickel.
Claim 15
Dependent Claim
40 words
The combination set forth in claim 13 wherein the crystallites of said core are oriented for maximum thermal conductivity in a plane parallel to its surfaces and extending between said marginal metallic layers for improved thermal conduction to said cooler.
Claim 16
Dependent Claim
37 words
The combination set forth in claim 14 wherein said copper to molybdenum ratio is from 15 to 40 volume percent to achieve a CTE of approximately 6 to 7 ppm/° C., and said packages are ceramic packages.
Claim 17
Dependent Claim
40 words
The combination set forth in claim 15 wherein said core is approximately 8/10 of the volume of said substrate and said face sheets are approximately 2/10 of the volume of said substrate to achieve a low weight high strength design.
Claim 18
Dependent Claim
68 words
A heat sinking substrate for surface mounted electronic device packages, said substrate comprising, in combination: A. a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bound together by coal tar pitch, said core having opposed, planar surfaces; and B. a metallic face sheet adhered to each planar surface, each face sheet having a coefficient of thermal of expansion suited to electronic device packages.
Claim 19
Dependent Claim
68 words
A heat sinking substrate for surface mounted electronic device packages, said substrate comprising, in combination: A. a core consisting of a rigid graphitic solid in which hexagonal graphite crystallites are bound together by coal tar pitch, said core having opposed, planar surfaces; and B. a metallic face sheet adhered to each planar surface, each face sheet having a coefficient of thermal of expansion suited to electronic device packages.
Claim 20
Dependent Claim
19 words
The heat sink substrate as set forth in claim 17 wherein said graphitic crystallites are obtained by fractionating petroleum.
Claim 21
Dependent Claim
41 words
The heat sink substrate as set forth in claim 18 wherein said core is formed by granular graphitic crystallites bound together by further fractionized coal tar pitch in an orientation favoring thermal conduction in a plane parallel to said core surfaces.
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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) | 1993-10-15 | 1994-04-16 | 1994-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-15 | 1998-04-16 | 1998-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-15 | 2002-04-16 | 2002-10-16 | $7700.00 | Window Closed / Lapsed |