Patent EP0147014A2 successfully refreshed from Google Patents.
EP0147014A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Multilayer printed circuit board structure
Assignee: Northrop Grumman Space and Mission Systems Corp
•
Filing: 1984-09-19
•
Granted: —
•
Expires: 2004-09-19
Abstract
Abstract A composite printed circuit board structure including multiple layers of graphite interleaved with layers of a dielectric material, such as a polytetraflouroethylene (PTFE) and woven glass laminate. Some of the dielectric layers are copper clad, and at least some of the graphite layers are positioned in close proximity to the copper cladding layers, to provide good heat dissipation properties. The PTFE provides a desirably low dielectric constant and the graphite also provides good mechanical strength and a low or negative coefficient of thermal expansion, to permit matching of the coefficient with that of chip carriers used to mount components on the circuit board.
Inventors
- 👤 Joseph David Leibowitz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 16:20
CPC Classifications
B; B32; B32B; B32B15/00; B32B15/04; B32B15/08; B32B15/085; B32B15/14; B32B15/20; B32B27/00; B32B27/32; B32B27/322; B32B7/00; B32B7/04; B32B7/12; B32B9/00; B32B9/005; B32B9/007; H; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/05; H05K1/056; H05K3/00; H05K3/46; H05K3/4611; H05K3/4641; B32B2260/00; B32B2260/02; B32B2260/021; B32B2260/04; B32B2260/046; B32B2262/00; B32B2262/10; B32B2262/106; B32B2307/00; B32B2307/20; B32B2307/204; B32B2307/30; B32B2307/302; B32B2457/00; B32B2457/08; H05K1/0313; H05K1/032; H05K1/034; H05K2201/00; H05K2201/01; H05K2201/0137; H05K2201/015; H05K2201/03; H05K2201/032; H05K2201/0323; H05K3/40; H05K3/42; H05K3/429; Y; Y10; Y10S; Y10S428/00; Y10S428/901; Y10T; Y10T428/00; Y10T428/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
141 words
A multilayer printed circuit board having a controllable coefficient of thermal expansion, good thermal conductivity and low dielectric constant, said circuit board comprising: a plurality of layers of conductive metal used to establish connections between components to be mounted on the board; a plurality of layers of graphite, at least some of which are positioned in close proximity to some of said layers of conductive metal, to provide a relatively low resistance path for the flow of heat from said layers of conductive metal; and a plurality of layers of dielectric material bonded together with said layers of copper and graphite, to yield a composite multilayer printed circuit board; said layers of graphite being positioned in a symmetrical manner with respect to the thickness of the composite board, and selected in number to provide a desired composite coefficient of thermal expansion.
Claim 2
Dependent Claim
141 words
A multilayer printed circuit board having a controllable coefficient of thermal expansion, good thermal conductivity and low dielectric constant, said circuit board comprising: a plurality of layers of conductive metal used to establish connections between components to be mounted on the board; a plurality of layers of graphite, at least some of which are positioned in close proximity to some of said layers of conductive metal, to provide a relatively low resistance path for the flow of heat from said layers of conductive metal; and a plurality of layers of dielectric material bonded together with said layers of copper and graphite, to yield a composite multilayer printed circuit board; said layers of graphite being positioned in a symmetrical manner with respect to the thickness of the composite board, and selected in number to provide a desired composite coefficient of thermal expansion.
Claim 3
Dependent Claim
66 words
A multilayer printed circuit board as set forth in claim 1, wherein: said graphite layers are formed from woven sheets of graphite impregnated with a bonding material; and said graphite sheets are bonded to adjacent sheets of conductive metal by a thin layer of insulating adhesive, whereby the layer of adhesive serves the additional purpose of electrically separating the conductive metal from the conductive graphite layer.
Claim 4
Dependent Claim
31 words
A multilayer printed circuit board as set forth in claim 2, wherein: said sheets of conductive metal are of copper; and said sheets of dielectric material include a polytetraflouroethylene (PTFE) material.
Claim 5
Dependent Claim
66 words
A multilayer printed circuit board as set forth in claim 1, wherein: said graphite layers are formed from unidirectional fibers of graphite impregnated with a bonding material; and said graphite sheets are bonded to adjacent sheets of conductive metal by a thin layer of insulating adhesive, whereby the layer of adhesive serves the additional purpose of electrically separating the conductive metal from the conductive graphite layer.
Claim 6
Dependent Claim
31 words
A multilayer printed circuit board as set forth in claim 4, wherein: said sheets of conductive metal are of copper; and said sheets of dielectric material include a polytetraflouroethylene (PTFE) material.
Claim 7
Dependent Claim
136 words
A multilayer printed circuit board having a controllable coefficient of thermal expansion, good thermal conductivity and low dielectric constant, said circuit board comprising: a plurality of layers of a dielectric material that includes polytetraflouroethylene, some of said layers being coated with patterned copper, as dictated by the nature of the components supported on the circuit board; and a plurality of layers of graphite, at least some of which are positioned in close proximity to some of said copper layers, to provide good thermal conduction for the dissipation of heat generated in the components mounted on the board; wherein said graphite layers are selected to provide a desired composite coefficient of thermal conductivity and are positioned across the thickness of the board in a symmetrical manner, to minimize bowing of the board in conditions of varying temperature.
Claim 8
Dependent Claim
136 words
A multilayer printed circuit board having a controllable coefficient of thermal expansion, good thermal conductivity and low dielectric constant, said circuit board comprising: a plurality of layers of a dielectric material that includes polytetraflouroethylene, some of said layers being coated with patterned copper, as dictated by the nature of the components supported on the circuit board; and a plurality of layers of graphite, at least some of which are positioned in close proximity to some of said copper layers, to provide good thermal conduction for the dissipation of heat generated in the components mounted on the board; wherein said graphite layers are selected to provide a desired composite coefficient of thermal conductivity and are positioned across the thickness of the board in a symmetrical manner, to minimize bowing of the board in conditions of varying temperature.
Claim 9
Dependent Claim
27 words
A printed circuit board as set forth in claim 4, wherein: said layers of graphite are formed from unidirectional graphite fibers impregnated with a plastic bonding material.
Claim 10
Dependent Claim
19 words
A printed circuit board as set forth in claim 7, wherein: said plastic bonding material is an epoxy resin.
Claim 11
Dependent Claim
27 words
A printed circuit board as set forth in claim 6, wherein: said layers of graphite are formed from unidirectional graphite fibers impregnated with a plastic bonding material.
Claim 12
Dependent Claim
19 words
A printed circuit board as set forth in claim 9, wherein: said plastic bonding material is an epoxy resin.
Claim 13
Independent Claim
87 words
A method of fabrication of circuit boards, comprising the steps of: impregnating a woven graphite cloth with a resin to form a plurality of solid graphite sheets; etching a plurality of copper-clad sheets of polytetraflouroethylene (PTFE) and woven glass with predefined circuit patterns; laminating the graphite sheets and the copper-clad sheets, together with other sheets of P T FE and woven glass, to form a composite printed circuit board with a selected coefficient of thermal expansion, good heat conductivity properties, good mechanical strength and low dielectric constant.
Claim 14
Independent Claim
87 words
A method of fabrication of circuit boards, comprising the steps of: impregnating a woven graphite cloth with a resin to form a plurality of solid graphite sheets; etching a plurality of copper-clad sheets of polytetraflouroethylene (PTFE) and woven glass with predefined circuit patterns; laminating the graphite sheets and the copper-clad sheets, together with other sheets of P T FE and woven glass, to form a composite printed circuit board with a selected coefficient of thermal expansion, good heat conductivity properties, good mechanical strength and low dielectric constant.
Claim 15
Dependent Claim
38 words
A method as set forth in claim 7, wherein said laminating step includes: applying an insulating adhesive layer between each graphite sheet and adjacent layers, whereby the adhesive layer also electrically insulates the graphite and copper cladding materials.
Claim 16
Dependent Claim
69 words
A method as set forth in claim 8, and further including the steps of: pre-drilling the graphite sheets, prior to said laminating step, at predetermined locations for via holes and mounting screw holes; filling the pre-drilled holes with a resin; drilling the laminated board at the predetermined hole locations, using a smaller diameter drill, to leave an annular sheath of insulating resin around each hole through a graphite sheet.
Claim 17
Independent Claim
87 words
A method of fabrication of circuit boards, comprising the steps of: impregnating a layer of unidirectional graphite fibers with a resin to form a plurality of solid graphite sheets; etching a plurality of copper-clad sheets of polytetraflouroethylene (PTFE) and woven glass with predefined circuit patterns; laminating the graphite sheets and the copper-clad sheets, together with other sheets of PTFE and woven glass, to form a composite printed circuit board with a selected coefficient of thermal expansion, good heat conductivity properties, good mechanical strength and low dielectric constant.
Claim 18
Independent Claim
87 words
A method of fabrication of circuit boards, comprising the steps of: impregnating a layer of unidirectional graphite fibers with a resin to form a plurality of solid graphite sheets; etching a plurality of copper-clad sheets of polytetraflouroethylene (PTFE) and woven glass with predefined circuit patterns; laminating the graphite sheets and the copper-clad sheets, together with other sheets of PTFE and woven glass, to form a composite printed circuit board with a selected coefficient of thermal expansion, good heat conductivity properties, good mechanical strength and low dielectric constant.
Claim 19
Dependent Claim
38 words
A method as set forth in claim 7, wherein said laminating step includes: applying an insulating adhesive layer between each graphite sheet and adjacent layers, whereby the adhesive layer also electrically insulates the graphite and copper cladding materials.
Claim 20
Dependent Claim
69 words
A method as set forth in claim 8, and further including the steps of: pre-drilling the graphite sheets, prior to said laminating step, at predetermined locations for via holes and mounting screw holes; filling the pre-drilled holes with a resin; drilling the laminated board at the predetermined hole locations, using a smaller diameter drill, to leave an annular sheath of insulating resin around each hole through a graphite sheet.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.