ADVANCED HEAT SINKS AND THERMAL SPREADERS
A heat sink assembly for an electronic device or a heat generating device(s) is constructed from an ultra-thin graphite layer. The ultra-thin graphite layer exhibits thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane and comprises at least a graphene layer. The ultra-thin graphite layer is structurally supported by a layer comprising at least one of a metal, a polymeric resin, a ceramic, and a mixture thereof, which is disposed on at least one surface of the graphite layer.
1 . A thermal management assembly for dissipating thermal energy from a heat-generating device, the assembly comprising:
a base adapted to be thermally coupled to the heat generating device; and
at least a heat sink thermally coupled to the base, the heat sink comprises at least a graphite layer having a first surface, a second surface, and a thickness comprising at least a graphene layer, wherein the graphite layer is obtained by cleaving at least a graphene layer from a graphite sheet wherein the graphite layer exhibits a thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane, and
the heat sink further comprises a support layer which comprises at least one of a metal, a polymeric resin, a ceramic, and a mixture thereof, the support layer is disposed on at least one surface of the graphite layer by at least a process selected from the group consisting of: coating, brushing, spraying, spreading, dipping, laminating, and powder coating.
2 . The thermal management assembly of claim 1 , wherein prior to the support layer being disposed on the graphite layer, the graphite layer is treated by one of plasma etching, ion etching, chemical etching, and combinations thereof.
3 . The thermal management assembly of claim 1 , wherein the support layer comprises parylene.
4 . The thermal management assembly of claim 3 , wherein the support layer is formed by applying parylene onto at least a surface of the graphite layer, and wherein paralyene is applied onto the surface by one of brushing, dipping, spraying, and a chemical vapor deposition process.
5 . The thermal management assembly of claim 1 , wherein the support layer comprises a metal foil backed by a thermally conductive adhesive layer.
6 . The thermal management assembly of claim 3 , wherein the support layer is disposed on at least one surface of the graphite layer by
pressing a metal foil layer backed by the thermally conductive adhesive against a graphite sheet having a thickness of at least 0.1 mm and comprising a plurality of graphite layers, and
peeling off the metal foil layer for at least a graphite layer to be cleaved off the graphite sheet and affixed to the thermally conductive adhesive backing of the metal foil layer.
7 . A heat dissipating fin for use in thermal management assemblies, the fin comprises at least a graphite layer having a first surface, a second surface, and a thickness comprising at least a graphene layer, wherein the graphite layer is obtained by cleaving at least a graphene layer from a graphite sheet exhibiting a thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane,
the graphite layer is reinforced by a support layer disposed on at least one surface of the graphite layer by at least a process selected from the group consisting of: coating, brushing, spraying, spreading, dipping, laminating, and powder coating.
8 . The heat dissipating fin of claim 7 , wherein the fin has a thickness ranging from 5 nanometer to 50 mil.
9 . The heat dissipating fin of claim 8 , wherein the fin has a thickness ranging from 10 nanometer to 30 mil.
10 . The heat dissipating fin of claim 7 , wherein the support layer comprises at least one of a resin, a metal, a ceramic, or mixtures thereof.
11 . The heat dissipating fin of claim 10 , wherein the support layer comprises at least one of: parylene; silicon nitride, silicon oxide; nano particles of aluminum oxide, silicium oxide, zirconium oxide, titanium oxide, antimony oxide, zinc oxide, tin oxide, indium oxide, cerium oxide, metal powder, cynoacrylate; a carbon film; perfluoropolyether; hexamethyldisilazane; perfluorodecanoic carboxylic acid; silicon dioxide; silicate glass; acrylic; epoxy; silicone; urethane; and a phenolic-based resin.
12 . The heat dissipating fin of claim 7 , wherein the graphite layer reinforced by a support layer disposed thereon is formed by pressing a metal foil layer backed by a thermally conductive adhesive against at least a surface of the graphite layer.
13 . The heat dissipating fin of claim 7 , wherein the graphite layer reinforced by a support layer disposed thereon is formed by pressing a metal foil layer having a thickness from 5.0 to 25 μm thick and backed by a layer of pressure sensitive adhesive against both surfaces of the graphite layer.
14 . The heat dissipating fin of claim 7 , wherein the graphite layer reinforced by a support layer disposed thereon is formed by coating at least a surface of the graphite layer by a plasma deposition process for the support layer to have a thickness of less than 500 nanometer.
15 . The heat dissipating fin of claim 7 , wherein the graphite layer reinforced by a support layer disposed thereon is fabricated into one of:
a radial or partially radial fin;
a folded fin having alternating and curved portions;
a corrugated fin having a plurality of cellular structures;
a plurality of fins in a splayed pattern with one bundled end and an expanded end with the fins at the expanded end being spaced apart from adjacent fins;
a rectangular fin;
a rectangular fin having a plurality of slits for defining at least an air passage through the heat sink;
a plurality of pin fins; and combinations thereof.
16 . The heat dissipating fin of claim 7 , wherein the graphite layer reinforced by a support layer disposed thereon is fabricated into a folded fin having alternating and curved portions, and wherein each curved portion has a plurality of vertical slits for defining at least an air passage through the heat sink.
17 . A thermal management assembly comprising a plurality of the heat dissipating fins of claim 14 .
18 . A cooling system comprising:
an integrated circuit board;
a processor coupled to the integrated circuit board;
a heat sink thermally coupled to the processor, the heat sink comprising a base to transfer heat away from the processor, and a fin thermally coupled to the base, the fin comprising at least a graphite layer having first surface, a second surface, and a thickness comprising at least a graphene layer, the graphite layer is obtained by cleaving at least a layer from a graphite sheet exhibiting a thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane,
the heat sink further comprising a support layer comprising at least one of a metal, a polymeric resin, a ceramic, and a mixture thereof, the support layer is disposed on at least one surface of the graphite layer by at least a process selected from the group consisting of: coating, brushing, spraying, spreading, dipping, laminating, and powder coating.
19 . A method for constructing a thermal management system, the method comprising:
constructing a fin by cleaving at least a graphite layer having a thickness of less than 1 mil from a sheet of graphite exhibiting a thermal conductivity which is anisotropic in nature and is greater than 500 W/m° C. in at least one plane, the graphite layer comprising at least a graphene layer;
coupling the fin to a base to form a heat sink; and
thermally coupling the heat sink to an integrated circuit such that the heat sink conducts thermal energy away from the integrated circuit during operation of the integrated circuit.
20 . The method of claim 19 , wherein the fin is coupled to the heat sink base by one of soldering, crimping, swaging, staking, brazing, bonding, welding, spot welding, using an adhesive.