Deformed Mesh Thermal Ground Plane

Some embodiments include a thermal ground plane comprising a first casing layer and a second casing layer where the outer periphery of the first casing layer and the outer periphery of the second casing layer are bonded to each other. The thermal ground plane including a working fluid disposed within the first casing layer and the second casing layer. The thermal ground plane may also include a permeable wick disposed between the first casing layer and the second casing layer; and a deformed mesh disposed between the first casing layer and the permeable wick, the deformed mesh comprising a mesh with deformed mesh portions that form vapor channels and nondeformed mesh portions that form liquid channels.

BACKGROUND

Recent developments of higher integration and higher performance electronic devices have led to increased heat dissipation requirements. Similarly, electronic device miniaturization has led to increased heat generation density. This is becoming increasingly important with the miniaturization and advancements in smart phones and other similar devices as well as with electronic vehicles.

SUMMARY

Some embodiments include a thermal ground plane comprising a first casing layer and a second casing layer where the outer periphery of the first casing layer and the outer periphery of the second casing layer are bonded to each other. The thermal ground plane including a working fluid disposed within the first casing layer and the second casing layer. The thermal ground plane may also include a permeable wick disposed between the first casing layer and the second casing layer; and a deformed mesh disposed between the first casing layer and the permeable wick, the deformed mesh comprising a mesh with deformed mesh portions that form vapor channels and nondeformed mesh portions that form liquid channels.

In some embodiments, deformed mesh comprises a plurality of fibers woven together. In some embodiments, the deformed mesh comprises a plurality of mesh layers. In some embodiments, the deformed mesh portions are mesh portions that have been compressed. In some embodiments, the deformed mesh comprises an array nondeformed mesh portions. In some embodiments, the deformed mesh comprises a mesh with a first surface that is substantially flat and a second surface that has been deformed to include a plurality of ridges or pillars.

In some embodiments, the deformed mesh is disposed between the first casing and the second casing with the second surface positioned toward the first casing. In some embodiments, the deformed mesh is disposed between the first casing and the second casing with the second surface positioned toward the permeable wick.

In some embodiments, the thermal ground plane may include a planar mesh disposed between the deformed mesh and the permeable wick.

In some embodiments, the permeable wick includes a plurality of pillars.

In some embodiments, the deformed mesh includes an internal artery.

In some embodiments, the deformed mesh includes a first mesh layer with a first pore size and a second mesh layer with a second pore size that is different than the first pore size.

In some embodiments, the deformed mesh comprises a metallic polymer, metal coated polymer, ceramic coated polymer, ALD coated polymer, copper coated steel, copper coated stainless steel.

In some embodiments, the permeable wick comprises permeable structures selected from the list consisting of a woven mesh, a nonwoven mesh, a plurality of pillars, a plurality of particles, one or meshes, a plurality of channels, a plurality of micropillars, and a plurality of microchannels.

Some embodiments include a thermal ground plane that includes a first casing layer and a second casing layer. In some embodiments, the outer periphery of the first casing layer and the outer periphery of the second casing layer are bonded to each other. A working fluid may be disposed within the first casing layer and the second casing layer. The thermal ground plane may include a plurality of structures disposed within the first casing layer and the second casing layer. In some embodiments, each of the plurality of structures include a mesh structure and an internal artery disposed within the mesh structure.

In some embodiments, each mesh structure comprises a plurality of mesh layers.

In some embodiments, the internal artery extends from the first casing to the second casing. In some embodiments, the internal artery is surrounded by the mesh structure. In some embodiments, each internal artery extends along an entire length of each respective mesh structure. In some embodiments, the internal artery comprises a plurality of internal arteries disposed within each mesh structure.

In some embodiments, the thermal ground plane may include a second mesh disposed between at least two of the mesh structures, the second mesh comprising a mesh having a higher permeability than the mesh structures.

DETAILED DESCRIPTION

A thermal ground plane is disclosed, that includes a first casing layer (e.g., first casing layer), a second casing layer (e.g., bottom casing), liquid structures, and vapor structures. Either or both the liquid structures, and vapor structures may include a deformed structure.

A thermal ground plane is a type of vapor chamber, in which the first casing layer and the second casing layer form a hermetic seal, and within that sealed region is a wick which is permeated with a liquid. The liquid may be in thermodynamic equilibrium with a saturated vapor phase. The vapor phase may permeate a cavity which is supported by some vapor structure. When heat is applied at any location, the liquid evaporates and increases the temperature of the vapor by a small amount. That increase in temperature results in a local area of increased pressure, which then generates a flow of the vapor away from the high pressure region, and thereby carries heat away by convection. The heat is rejected away from the vapor core in the colder regions when the vapor condenses, and the condensate is pulled back to the hot region by capillary forces within the wick. The utilization of convection allows the thermal ground plane system to achieve high amounts of heat transfer with low temperature gradients, and thereby a high effective thermal conductivity. The capillary forces in the wick may be high enough to overcome any drag forces in the wick, drag forces in the vapor phase, pressure drops associated with phase change, and hydrostatic effects of gravity. The drag forces are influenced by thermosphysical properties of the fluids and the effective permeability of the wick and vapor core structures.

In some embodiments, a thermal ground plane my enclose a working fluid. The working fluid may generate a gas-liquid phase change under an atmosphere in between the first casing and the second casing. The working fluid may, for example, comprise water, alcohol, alternative fluorocarbon or the like. The alternative fluorocarbon, for example, may follows the list established by the US Environmental Protection Agency (EPA). In some embodiments, the working liquid be an aqueous compound. In some embodiments, the working liquid be water.

FIG. 1is a diagram of a TGP100according to some embodiments. In this example, the TGP100includes a first casing layer110, a second casing layer115, a liquid structure120, and/or a vapor structure125. The TGP100, for example, may operate with evaporation, vapor transport, condensation, and/or liquid return of water or other cooling media for heat transfer between the evaporation region130and the condensation region135. The first casing layer110may include copper, polyimide, polymer-coated copper, copper-cladded Kapton, etc. The second casing layer115may include copper, polyimide, polymer-coated copper, copper-cladded Kapton, etc. In some embodiments, the first casing layer110and the second casing layer115of the TGP100may be sealed together using solder, laser welding, ultrasonic welding, electrostatic welding, or thermo-pressure compression or a sealant140. In some embodiments, the first casing layer110and the second casing layer115of the TGP100may include the same or different materials.

The evaporation region130and the condensation region135may be disposed on the same layer: the first casing layer110or the second casing layer115. Alternatively, the evaporation region130and the condensation region135may be disposed on different layers of the first casing layer110and the second casing layer115

In some embodiments, the vapor structure125and/or liquid structure120may be formed from an initial structure (e.g., a mesh) that has been deformed into various geometric shapes that may improve thermal transport, the flow permeability, the capillary radius, the effective thermal conductivity, the effective heat transfer coefficient of evaporation, and/or the effective heat transfer coefficient of condensation. In some embodiments, the initial structure may include multiple layers of mesh.

In some embodiments, the outer periphery of the first casing layer110and the outer periphery of the second casing layer115may be sealed such as, for example, hermetically sealed.

FIG. 2is a diagram of a TGP200according to some embodiments with a vapor structure125, a liquid structure120, and a planar mesh210disposed between the vapor structure125and the liquid structure120. In some embodiments, the planar mesh210may, for example, enhances the capillary effect, permeability effect, or the heat transfer associated with phase change between liquid and vapor.

The planar mesh210, for example, may comprise a woven mesh or a nonwoven mesh. The planar mesh210, for example, may comprise a metallic polymer, metal coated polymer, ceramic coated polymer, ALD coated polymer, copper coated steel, copper coated stainless steel, etc. A nonwoven mesh may comprise a mesh where the fibers are randomly distributed. A nonwoven mesh may comprise a sheet with ordered or nonordered array of holes etched in the sheet. The sheet may be metallic or polymer. A woven mesh may comprise a ordered distribution of fibers.

In some embodiments, the liquid structure120may comprise a porous structure. In some embodiments, the liquid structure120may produce capillary pressure that allows liquid to flow through the liquid structure120.

The planar mesh210, for example, may separate the vapor structure125and the planar mesh210. The planar mesh210, may enhance the capillary effect, permeability effect, or the heat transfer associated with phase change between liquid and vapor.

A mesh, for example, may comprise a woven mesh or a nonwoven mesh. A mesh, for example, may comprise a metallic polymer, metal coated polymer, ceramic coated polymer, ALD coated polymer, copper coated steel, copper coated stainless steel, etc. A nonwoven mesh may comprise a mesh where the fibers are randomly distributed. A nonwoven mesh may comprise a sheet with ordered or nonordered array of holes etched in the sheet. The sheet may be metallic or polymer. A woven mesh may comprise a ordered distribution of fibers.

FIG. 3Ais a diagram of a TGP300according to some embodiments. The vapor structure125includes a deformed mesh305. The deformed mesh305may include a planar member that has been deformed to include a plurality of pillars310. The plurality of pillars310may comprise corrugated pillars. Each or a majority of the plurality of pillars310may extend from the first casing layer110to the planar mesh210. In some embodiments, vapor may flow between the plurality of pillars310. In some embodiments, deformed mesh305may comprise any material that can be deformed into a shape and/or that can support the vapor cavity. In some embodiments, the deformed mesh305may comprise copper, steel, copper-coated steel, other metals, copper-coated polymer, ceramic coated polymer, and/or ceramic coated metal. In some embodiments, the deformed mesh305may be encapsulated with copper.

In some embodiments, the deformed mesh305may be solid. In some embodiments, the deformed mesh305may be porous, which may, for example, allow vapor to flow between cavities defined by the first casing layer110and the deformed mesh305.

In some embodiments, the plurality of pillars may be supported by particles of material315under, below, above, or on both sides of the plurality of pillars310, as shown in the side view of TGP350shown inFIG. 3B. InFIG. 3Bthe particles of material are placed within the deformations that create the plurality of pillars310.

In some embodiments, the plurality of pillars310may be formed with the deformed mesh305by depressing pillar shapes into the deformed mesh305. The deformed mesh305may undergo either inelastic or plastic deformation, as shown inFIG. 4AandFIG. 4B. Prior to deformation, the deformed mesh305may be in a planar state and placed between top press405and a bottom press410as shown inFIG. 4A. The top press405, for example, may include a plurality of positive extensions and the bottom press410may include a plurality of corresponding recesses. The top press405and the bottom press410may be pressed together deforming the deformed mesh305as shown inFIG. 4B.

FIG. 5Ais an illustration of a TGP500with a liquid structure120comprising a mesh510and a permeable wick according to some embodiments. In some embodiments, the mesh510may include a material having a plurality of holes. These holes, for example, may have a diameter of less than about 40 microns. The mesh510may be bonded to the permeable wick with electroplating, thermo-sonic bonding, or thermo-compressive bonding. In some embodiments the mesh510mesh may be formed by flattening a woven mesh, by electroplating, and/or by etching a planar member. In some embodiments, the mesh510may comprise copper, polyimide, polyester, polycarbonate, glass, other metals, other polymers, or other ceramics. In some embodiments, the mesh510may be substantially flat.

In some embodiments, the permeable wick may include a plurality of pillars505disposed on the second casing layer115. The plurality of pillars505may, for example, be uniformly or nonuniformly distributed. The plurality of pillars505may, for example, be a plurality of micropillars. The plurality of pillars505may be formed, for example, by mechanical scribing, milling, chemical etching, photolithography, etching, and/or electroplating.

The TGP500may include a vapor structure125that comprises a plurality of particle structures515that each include a plurality of particles. The plurality of particles may include sintered particles.

FIG. 5Bis an illustration of a TGP550with a liquid structure120comprising a mesh510and a permeable wick according to some embodiments. The permeable wick may include a plurality of particles525such as, for example, particles comprising copper, glass, metals, other ceramics, or composites.

FIG. 6Ais an illustration of a TGP600with a liquid structure120comprising a mesh510and a permeable wick according to some embodiments. The permeable wick may include one or more meshes520.

FIG. 6Bis an illustration of a TGP650with a liquid structure120comprising a mesh510and a permeable wick according to some embodiments. Although the permeable wick in the figure is shown with a plurality of plurality of pillars505any type of permeable wick may be used such as, for example, the plurality of particles structures515, the one or more meshes520, etc. The mesh510, may include a textured surface610. In some embodiments, the textured surface may be textured on the side of the mesh510facing the vapor structure125. The textured surface may, for example, help pull liquid into the textured area by capillary forces associated with texturing, which may increase the area associated with heat evaporation.

When liquid evaporates within a TGP, heat may flow through the vapor-liquid interface. By extending the area of the vapor-liquid interface, the thermal resistance of evaporation may be reduced. In some embodiments, the mesh510may be textured with a textured surface610on the vapor-side such that liquid may be pulled away from the pores into the textured area by capillary forces associated with texturing, which may increase the area associated with heat evaporation. In some embodiments, the textured surface610may be formed by chemically etching the mesh510with a non-uniform etch process. In some embodiments, the textured surface610may be formed by laser or mechanical scribing, sintering particles to the surface of the planar mesh, patterning the planar mesh with out-of-plane features by photolithography, and/or etching or deposition, non-lithography based deposition through a template such as inverse opal structures or plating through randomly distributed defects in a film, non-templated anisotropic deposition techniques such as rapid plating, and/or non-templated anisotropic etching techniques such as de-alloying, etc.

FIG. 7Ais an illustration of a TGP700with the perimeter of the mesh510bonded to a solid wall705such that, for example, the vapor-liquid interface is constrained to the pores within the mesh510and cannot form along the perimeter. The capillary force of such vapor liquid interface, for example, can keep vapor from impinging into the liquid structure120. In some embodiments, the solid wall705can include porous material where the pore size is smaller or similar size to the capillary diameter of the mesh510. In some embodiments, the solid wall705can include foam, sintered particles, micropillars, mesh, etc

FIG. 7Bis an illustration of a sideview of a TGP700with the perimeter of the mesh510bonded to the second casing layer115. The mesh510may include one or more bends around the perimeter to connect the mesh510to the second casing layer115.

FIG. 8Ais an illustration of a side view of a TGP800with a vapor structure125including a folded mesh805according to some embodiments. In some embodiments, the folded mesh805can be compressed or folded at folds810in a non-uniform fashion such that each layer of material is of different dimensions. In some embodiments, the folded mesh805can include any porous material or any solid material that is made to be porous before or after folding. In some embodiments, the folded mesh805can be made of multiple layers of mesh. In some embodiments, the folds810in the folded mesh805may form ribs within the vapor structure125that extend along y-direction (into the page).

In some embodiments, the ribs can be formed into pillars820by compressing the folded mesh at intervals in the y-direction, as shown inFIG. 8B. The pillars820can be formed by folding and/or by pressing the folded mesh805between an upper press860and a lower press865to form pillars820.

FIG. 9Ais an illustration of a sideview of a TGP900with a deformed mesh902that includes deformed mesh portions905and nondeformed mesh portions910according to some embodiments. In some embodiments, the deformed mesh portions905may be formed in a pattern.

The deformed mesh portions905may form vapor channels915between the nondeformed mesh portions910. The deformed mesh902may be disposed within the TGP900on a permeable wick920. The deformed mesh902, for example, may include either woven or nonwoven mesh. The vapor channels915may occur within gaps between nondeformed mesh portions910and the first casing layer110. The deformed mesh portions905(and/or the vapor channels) may be created by any deformation process such as, for example, the deformation process shown inFIGS. 10A, 10B, and 10C.

In some embodiments, the deformed mesh902may include multiple layers of the same type of mesh (e.g., the same thread count or same pore sizes) stacked on upon another or multiple layers of different types of mesh (e.g., different thread counts or different pore sizes) stacked one upon another. In some embodiments, the deformed mesh902may include spacing layers between different mesh layers.

In some embodiments, the nondeformed mesh portions910(e.g., the liquid channels) may comprise any of a variety of different configurations such as, for example, pillars (as shown inFIG. 9B), elongated channels (e.g., having a rectangular cross section), or overhangs. In some embodiments, the height of the nondeformed mesh portions910(e.g., the liquid channels) can be greater than the sum of the thickness of the deformed mesh portions905and the permeable wick920.

FIG. 9Bis an illustration of a top view of the TGP900according to some embodiments. The nondeformed mesh portions910are shown in array of nondeformed mesh portions910within the mesh. The nondeformed mesh portions910(e.g., the liquid channels), for example, may have a width less than about 10, 5, 2, 1, or 0.5 mm, a center-to-center pitch less than about 10, 5, 2, 1, or 0.5 mm, and/or a height less than about 2, 1, 0.5, 0.2, or 0.1 mm. The nondeformed mesh portions910(e.g., the liquid channels), for example, may have a cross-section that is square, rectangle, circular, oval, or star-shaped.

In some embodiments, the deformed mesh portions905may be formed by compressing multiple layers of mesh through a compressive mask such as, for example, as shown inFIGS. 10A, 10B, and 10C. In some embodiments, the mask is formed of copper, steel, other metal, other ceramic, or polymer.

In some embodiments, the deformed mesh portions905may be bonded to the permeable wick920. In some embodiments, the permeable wick920may be a woven or nonwoven mesh layer as shown inFIG. 11Awith or without a planar mesh layer. In some embodiments, the permeable wick920may include a plurality of pillars, a plurality of particles, one or meshes, a plurality of channels, a plurality of micropillars, a plurality of microchannels, etc.

The deformed mesh portions905may be created, formed, compressed, etc. such as, for example, by the deformation process shown inFIGS. 10A, 10B, and 10C. A top press1005and a bottom press1010may press one or more nondeformed meshes1015to create deformed mesh902.

FIG. 11Ais an illustration of a side view of a TGP1100with a deformed mesh902according to some embodiments. The TGP1100includes a deformed mesh portions905, a planar mesh1110, and/or a permeable wick. The planar mesh1110may ensure the mesh effect in the nondeformed mesh portions910(e.g., the liquid channels) may maintain high capillary performance. In some embodiments, the pores in the planar mesh1110may be smaller than the pores in mesh that comprise the deformed mesh portions905. The permeable wick may include a mesh1105such as, for example, a woven mesh or a nonwoven mesh.

FIG. 11Bis an illustration of a side view of a TGP1150with a deformed mesh902according to some embodiments. The TGP1150includes a deformed mesh portions905, a planar mesh1110, and/or a permeable wick that includes pillars1115and walls1120disposed on the second casing layer115. In some embodiments, the walls1120may include the same shape, material, size, etc. as the pillars1115. Both, for example, can be made by hot embossing. The walls1120, for example, may bound the pillars1115or portions of the permeable wick. The walls1120, for example, may ensure that the high capillary pressure will prevent ingress of vapor into the pillars1115.

In some embodiments, the deformed mesh portions905may or may not be bonded with the first casing layer110. In some embodiments, the deformed mesh portions905may or may not be bonded with the second casing layer115. In some embodiments, bonding may include thermocompression bonding, thermosonic bonding, electroplating, etc.

FIG. 12Ais an illustration of a side view of a TGP1200according to some embodiments. The deformed mesh portions905is flipped relative to the orientation within the TGP of the deformed mesh portions905shown inFIG. 11B. The compressed portion of the deformed mesh portions905, for example, may be disposed on or bonded with the first casing layer110. The nondeformed mesh portions910(e.g., the liquid channels), for example, may extend away from the first casing layer110toward the planar mesh1110and/or toward the pillars1115. The ends of the nondeformed mesh portions910(e.g., the liquid channels), for example, may be coupled with the planar mesh1110.

FIG. 12Bis an illustration of a side view of a TGP1250according to some embodiments. The TGP1250, for example, may include a deformed mesh1205with upper deformations and lower deformations. The upper deformations, for example, may include liquid channels1210in the form of mesh pillars and vapor channels1215in the voids between the mesh pillars. The lower deformations, for example, may include liquid channels1220in the form of mesh pillars and vapor channels1225in the voids between the mesh pillars.

In some embodiments the layers of the deformed mesh1205may include meshes with different mesh weave types, thread count, wire diameter, or mesh material. In some embodiments, the lower deformations may be selectively compressed in the same or a different manner as the selective compression of the upper deformations.

The deformed mesh1205may be created by the deformation process shown inFIGS. 13A, 13B, and 13C. A top press1305and a bottom press1310may press a plurality of nondeformed meshes1315to create deformed mesh1205.

FIG. 14is an illustration of a side view of a TGP1400according to some embodiments. The TGP1400may include a first deformed mesh1405forming a vapor structure. The first deformed mesh1405, for example, may include a plurality of layers. The TGP1400may include a second deformed mesh1410forming a liquid structure. The second deformed mesh1410, for example, may include a plurality of layers. A planar mesh1415may be disposed between the first deformed mesh1405and the second deformed mesh1410. The planar mesh1415, for example, may ensure the mesh effect in the non-compressed regions maintains high capillary performance.

In some embodiments, the pitch between deformations of the first deformed mesh1405may be larger than the pitch between deformations of the second deformed mesh1410. In some embodiments, the height of the deformations of the first deformed mesh1405may be larger than the height of the deformations of the second deformed mesh1410. In some embodiments, the number of deformations of the first deformed mesh1405may be fewer than the number of deformations of the second deformed mesh1410.

FIGS. 15A-15Eillustration a process for creating a liquid wick according to some embodiments. The process starts with a mesh1505as shown inFIG. 15A. The mesh1505may be planar. The mesh1505may be flattened as shown inFIG. 15B. Additionally or alternatively, the planar mesh may be formed by photo-lithography and etching or electroplating, by etching through a template, by selective decomposition such as de-alloying, etc. The mesh1505may I include a plurality of woven or nonwoven fibers.

The mesh1505may be deformed to include a pattern having a plurality of pillars using a press fixture with male and female sides as shown inFIG. 15C. The mesh1505may be coupled with the second casing layer115(or substrate) as shown inFIG. 15DandFIG. 15E.

FIG. 16Ais an illustration of a side view of a TGP1600according to some embodiments. The TGP1600may include a deformed mesh1605is similar to deformed mesh1405with upper deformations and lower deformations. The upper deformations, for example, may include liquid channels in the form of mesh pillars1610and vapor channels in the voids1615between the mesh pillars1610. The lower deformations, for example, may include liquid channels in the form of mesh pillars1620and vapor channels in the voids1625between the mesh pillars.

The deformed mesh1605may include small deformations1635compressed into the compressed portions of the deformed mesh1605. The small deformations1635, for example, may extend out of plane relative to the compressed portions of the deformed mesh1605as shown inFIG. 16B. As another example, the small deformations1635, for example, may be in plane relative to the compressed portions of the deformed mesh1605. In some embodiments, the deformed mesh1605may be patterned by deformation including compression, folding, etching, plating, boding, etc.

The deformed mesh1605can be formed using a press as shown inFIGS. 17A, 17B, and17C.

FIG. 18Ais an illustration of a side view of a TGP1800having a permeable wick formed within the bottom layer1805according to some embodiments. The permeable wick may include a plurality of indentations1810that form a plurality of microchannels. In some embodiments, the indentations1810can be formed by cold-pressing or hot-pressing a shape into a bottom layer1805as shown inFIGS. 18B and 18C. In some embodiments, the bottom layer1805may include copper, polymer, copper-clad polymer, or other elastic materials. A planar mesh210may be disposed on the deformed bottom layer1805.

FIG. 19Ais an illustration of a side view of a TGP1800having a permeable wick formed in a soft material1915that is disposed on the bottom layer1905according to some embodiments. The permeable wick may include a plurality of indentations1910that form a plurality of microchannels. In some embodiments, the soft material may include hydrogen-annealed copper, polymer, thermoplastic polyimide, polysulfone polymers, polyethylene naphthalate, copper-clad polymer, or other elastic materials. In some embodiments, the indentations1910can be formed by cold-pressing or hot-pressing a shape into a soft material1915as shown inFIGS. 19B and 19C.

FIG. 20Ais an illustration of a side view of a TGP2000with a deformed mesh according to some embodiments. The TGP2000may include a mesh structure2005from undeformed portions of the deformed mesh. Vapor channels2010, for example, may be formed by the deformed portions of the deformed mesh and the mesh structure2005. The mesh structure2005, for example, may extend to the first casing layer110.

The physics of vapor transport through the vapor channel2010show that the pressure drop of the vapor may be proportional to the cube of the channel height. This non-linear behavior, for example, may mean that if the height of the vapor channels2010is increased in some regions and reduced in regions parallel to the flow, then there may be a net benefit. Such a condition may be met by arteries within the vapor channel2010. The mesh structure2005may comprise a plurality of mesh layers stacked one upon another forming the mesh structure2005.FIG. 20Bis an illustration of a top view of the TGP2000.

In some embodiments, the vapor channel2010may be defined by the first casing layer110, a mesh layer, and the sides of one or more mesh structure2005. Some vapor channels2010may also be defined by the edge of the TGP2000.

FIG. 20Cis an illustration of a side view of a TGP2050according to some embodiments. The TGP2050may be similar to the TGP2000with the mesh structures2015that do not extend to the first casing layer110.

FIG. 21Ais an illustration of a side view andFIG. 21Bis an illustration of a top view of a TGP2100according to some embodiments. The liquid structures2005includes a mesh support pillar2115that extends from the top of the liquid structures2005to the first casing layer110.

FIG. 22Ais an illustration of a side view andFIG. 22Bis an illustration of a top view of a TGP2200according to some embodiments. The liquid structures2005may include a mesh support pillar2115that extends from the top of the liquid structures2005to the first casing layer110. The vapor channels2010may include a vapor-support pillar2215that extends from the vapor channels2010to the first casing layer110.

FIG. 23Ais an illustration of a side view andFIG. 23Bis an illustration of a top view of a TGP2300according to some embodiments. The TGP2300includes liquid structures2005that have portions that extend to the first casing layer110and other portions that do not extend to the first casing layer110with a gap2310. Vapor may flow along the arteries in the vapor channels2010defined by the liquid structures2005as shown by arrow2335. Vapor may also flow between arteries in the vapor channels2010through gaps2310within the liquid structures2005. Thus, liquid may flow through the liquid structures2005and vapor may flow across the liquid structures2005through the gaps2310. The gaps2310in the liquid structures2005are not aligned. In this example, the gaps2310in the liquid structures2005are substantially not aligned across the TGP2400.

FIG. 24Ais an illustration of a side view andFIG. 24Bis an illustration of a top view of a TGP2400according to some embodiments. In this example, the gaps2310in the liquid structures2005are substantially aligned across the TGP2400.

FIG. 25is an illustration of a top view of a TGP2500according to some embodiments. The TGP2500includes a number of different arrangements of arteries, liquid structures, and/or vapor structures.FIG. 26Ais an illustration of a side view of the TGP2500along line A where the vapor channel2010includes a bottom mesh layer and the liquid structures2005either extend to the first casing layer110or extend nearly to the first casing layer110such as, for example, with mesh support pillars2115. In some embodiments, the vapor channel2010may be defined by the first casing layer110, the bottom mesh layer2605, and the sides of one or more liquid structures2005. Some vapor channels2010may also be defined by the edge of the TGP2500.

FIG. 26Bis an illustration of a side view of the TGP2500along line B. Along this portion of the TGP2500includes a bottom mesh layer2605on the second casing layer115.

FIG. 26Cis an illustration of a side view of the TGP2500along line C. Along this portion of the TGP2500that does not include bottom mesh layer2605on the second casing layer115and includes vapor channel2010and mesh structure2005. In some embodiments, the bottom mesh layer2605may include sintered particles, micropillars, microchannels, etc.

In some embodiments, an evaporation region (e.g., evaporation region130) may be disposed at or near portions of the TGP2500shown inFIG. 26AorFIG. 26B.

FIG. 27Ais an illustration of a side view of a TGP2700, which is similar to the TGP2500shown inFIG. 26Aaccording to some embodiments. The TGP2700may include a capping mesh2705on top of the bottom mesh layer2605. The capping mesh2705, for example, may have a pore size that is smaller than the pore size of the bottom mesh layer2605and/or the pore size of the mesh comprising the mesh structure2005.

FIG. 27Bis an illustration of a side view of the TGP2730, which is similar to the TGP2500shown inFIG. 26Baccording to some embodiments. The TGP2730may include a capping mesh2705on top of the bottom mesh layer2605. The capping mesh2705, for example, may have a pore size that is smaller than the pore size of the bottom mesh layer2605.

FIG. 27Cis an illustration of a side view of the TGP2760, which is similar to the TGP2500shown inFIG. 26Caccording to some embodiments. The TGP2760may include a capping mesh2705on top of one layer of the mesh that comprise the mesh structure2005. The capping mesh2705, for example, may have a pore size that is smaller than the pore size of the mesh that comprise the mesh structure2005.

FIG. 28Ais an illustration of a side view of the TGP2800according to some embodiments. The TGP2800is similar to the TGP2760shown inFIG. 27C. The TGP2800may include a capping mesh2805on top of at least the bottom mesh2820that comprise the mesh structure2005. The capping mesh2805may include one or more wall portions2810. The wall portions2810may extend around the perimeter of the bottom mesh2820and/or the mesh structure2005. In some embodiments, the wall portions may be formed by a solid material or one which has a low pore size (e.g., less than the pore sized of the capping mesh2805or bottom mesh2820or any mesh in the mesh structure2005), such that the capillary force of the capping mesh2805and wall portions2810together may prevent or restrict the ingress of vapor into the mesh structure2005. In some embodiments, the wall portions2810can be a simply connected geometry or have multiple cutout regions according to artery type designs. In some embodiments, the capping mesh2805may enhance the capillary force in a through-plane direction.

FIG. 28Bis an illustration of a side view of the TGP2830according to some embodiments. The TGP2830is similar to the TGP2760. The TGP2830may include a capping mesh2840on top of at least one layer of the bottom mesh2820that comprises at least a portion of the mesh structure2005. The capping mesh2840may also be coupled with the second casing layer115.

FIG. 28Cis an illustration of a side view of the TGP2860according to some embodiments. The TGP2800is similar to the TGP2760. The TGP2860may include a capping mesh2840on top of a plurality of the mesh2820that comprise the mesh structure2005or the entire liquid structure. The capping mesh2840may also be coupled with the second casing layer115.

In some embodiments, the capillary pressure may be low and/or the spacing between features (e.g., pore spacing in mesh structure2005) may be large such as 75, 100, 150, 200 micron, etc. The capping mesh2840my have small feature sizes, such as 1, 5, 10, 25, 50 um etc., which may create higher capillary pressure. For example, the mesh structure2005may have a pore size of about 250 microns and the capping mesh2840may have a pore size of about 50 microns. As another example, the mesh structure2005may have a pore size of about 50 microns and the capping mesh2840may have a pore size of about 5-10 microns.

FIG. 29Ais an illustration of a side view of a TGP2900with deformed mesh2910and internal arteries2905according to some embodiments. The deformed mesh2910may include internal arteries2905. The internal arteries, for example, may allow for high permeability of the liquid flow. The internal arteries, for example, may be surrounded by mesh that comprises the deformed mesh2910. The internal arteries, for example, may be surrounded by porous liquid structures such as sintered particles, microposts, etc. In some embodiments, the length of the internal arteries2905may extend along the entire length or a substantial portion of the deformed mesh2910.

FIG. 29Bis an illustration of a side view of a TGP2950with deformed mesh2910and internal arteries2905according to some embodiments. The deformed mesh2910may include internal arteries2905that extend from the first casing layer110to the second casing layer115(or a permeable wick or a planar mesh). Thus, the internal arteries2905may be surrounded by a mesh that defines the liquid structure, the first casing layer110, the second casing layer115, and/or liquid structures such as sintered particles, microposts, etc.

In some embodiments, internal arteries2905may enhance the thermal resistance of a TGP by a factor of 2.

In some embodiments, the deformed mesh2910and the internal arteries2905may be disposed upon or beneath a permeable wick. In some embodiments, a planar mesh may be disposed between the deformed mesh2910and a permeable wick.

The deformed mesh2910may form vapor channels2915in between deformed mesh2910.

FIG. 30is an illustration of a top view of a TGP3000having two different types of deformed mesh structure2910A,2910B according to some embodiments. The deformed mesh structure2910A, for example, may include internal arteries2905A that extend along a substantially length of the deformed mesh structure2910A.

The deformed mesh structure2910B, for example, may include internal arteries2905B that may not extend along the entire length of the deformed mesh structure2910B. The internal arteries2905B may comprise a plurality of internal arteries2905B with mesh portions3005in between. This may, for example, prevent the spreading of vapor along the whole artery if there is ingress of vapor into one of the liquid flow open areas.

FIG. 31is an illustration of a side view of a TGP3100with deformed mesh2910and internal arteries2905according to some embodiments. In some embodiments, the deformed mesh2910may include internal arteries3110that includes a wick structure that has a higher porosity than the surrounding mesh comprising the deformed mesh2910, such as pillars, coarse mesh, particles, etc. The internal arteries3110, for example, may extend from the first casing layer110to the second casing layer115. The internal arteries3110, for example, may not extend from the first casing layer110to the second casing layer115.

FIG. 32Ais an illustration of a side view of a TGP3200with a vapor core3205that is formed by a layer of deformed mesh3210according to some embodiments. In some embodiments, the deformed mesh3210may comprise a single layer. In some embodiments, the deformed mesh3210may include a coarse mesh (e.g., a mesh with large pores such as, for example, about 0.5, 1.0, 1.5, 2.0, 2.5, etc. mm). As vapor flows through a porous media (e.g., a mesh), for example, resistance and/or pressure drop may be proportional to the inverse square of the hydraulic radius of the flow. As a result, a deformed mesh3210with two small pores, for example, may have much higher resistance than a deformed mesh3210with a single larger pore. In some embodiments, the deformed mesh3210may support the vapor core.

In some embodiments, the deformed mesh3210may extend across a diagonal between the first casing layer110and the planar mesh210dividing the flow into 2 regions, which may result in an increase in flow resistance. In some embodiments, a diagonal deformed mesh3210can be deformed to allow the majority of the flow through a vapor core3205with large pores. In some embodiments, wires comprising the mesh of the deformed mesh3210can be further deformed to increase the flow area. In some embodiments, the deformation can promote flow in a single direction, while maintaining higher flow resistance in a perpendicular direction. In some embodiments, the TGP vapor core can include multiple different regions with different deformed meshes3210to promote the vapor flow in different directions within each region.

In some embodiments, a plurality of particles3215may be disposed between the deformed mesh3210and the first casing layer

FIG. 32Bis an illustration of a side view of a TGP3250with a vapor structure3255and a liquid structure3265defined by microparticles and/or nanoparticles according to some embodiments. The liquid structure3265may be defined by a plurality of pillars or structures3270formed from microparticles and/or nanoparticles disposed on the second casing layer115. The vapor structure3255may be formed by a plurality of pillars or structures3260from microparticles and/or nanoparticles disposed on the first casing layer110. The width and/or height of the plurality of pillars or structures of the vapor structure3255may be larger than either or both the width and/or height of the plurality of pillars or structures of the liquid structure3265. For example, the plurality of pillars or structures3260may be made from particles (e.g., sintering micro/nano particles) with a width about 0.3 mm to about 1.0 mm and/or a height about 0.1 mm to 0.2 mm. The plurality of pillars or structures3270, for example, may be made from particles (e.g., sintering micro/nano particles) with a width about 0.075 mm to about 0.2 mm. The plurality of pillars or structures3270, for example, may be made from particles (e.g., sintering micro/nano particles) with a width about 0.02 mm to about 0.075 mm.

In some embodiments, the microparticles and/or nanoparticles may be sintered together to form pillars. In some embodiments, the microparticles and/or nanoparticles may comprise copper, glass, other metals, or other ceramics. In some embodiments, the pillars may include microparticles and/or nanoparticles having different radii. In some embodiments, a fraction of the particles may sinter to bond to the remaining microparticles and/or nanoparticles and form a solid pillar, such as, for example, with copper nanoparticles sintering to seal copper microparticles.

FIGS. 33A, 33B, and 33Cillustrate a steps for fabricating a TGP with microparticles and/or nanoparticles according to some embodiments. In some embodiments, a screen printing process may be used.FIG. 33Ashows a template3305on the second casing layer115.

FIG. 33Bshows a plurality of microparticles and/or nanoparticles placed between the template. In some embodiments, the microparticles and/or nanoparticles can be deposited as a paste that may include microparticles and/or nanoparticles, solvent, and/or binder. In some embodiments, the solvent may include isopropanol, acetone, water, or other organic or inorganic solvents. In some embodiments, the binder may be polyvinyl alcohol, stearic acid, or another binder.

In some embodiments the microparticles and/or nanoparticles may be cleaned of oxides prior to placing the microparticles and/or nanoparticles on the second casing layer115using acid vapor, liquid acid, hydrogen bearing gas, or hydrogen-bearing plasma.

In some embodiments, the microparticles and/or nanoparticles may be sintered at elevated temperatures. In some embodiments, microparticles and/or nanoparticles sinter to a mesh layer to form the wick or vapor structure. In some embodiments, the microparticles and/or nanoparticles may be sintered in a vacuum environment, in an inert gas atmosphere, or in a reducing atmosphere. In some embodiments, the pillars formed by sintering may be bonded to a mesh layer at an elevated temperature and/or subsequently bonded to a cladding layer at lower temperature.

FIG. 33Cshows the microparticles and/or nanoparticles after the template3305has been removed or etched away.

FIGS. 34A, 34B, and 34Cillustrate a side view of a wick structure3400(or permeable wick) of a TGP according to some embodiments. The wick structure3400, for example, may be part of a TGP and may include various other wicks, meshes, casing, layers, etc. The wick structure3400, for example, may include a plurality of high-permeability region3415and a plurality of low-permeability regions3410. In some embodiments, the wick structure3400may include a planar mesh210. The physics of capillary driven liquid flow dictate that wick structures with high permeability (e.g., high-permeability region3415) may also have high capillary radius locally; and structures with low capillary radius (e.g., low-permeability regions3410) may also have low permeability. The capillary pressure may be determined by the capillary radius at the vapor-liquid interface, rather than the capillary radius in the regions of the wick that are saturated with liquid. It may be possible to have a region of high permeability completely surrounded by regions of low permeability and high capillary pressure, and in such a case the flowing liquid will experience low flow resistance of the high permeability region as well as the high capillary pressure of the low permeability region. One possible issue that may arise is if a vapor bubble3420forms within a high-permeability region3415, then the vapor bubble3420can expand and cause that region of the wick structure3400to dry out, shown inFIG. 34BandFIG. 34C. A vapor bubble3420, for instance, could form from nucleate bubbles in the high-permeability region3415or from defects in a low-permeability region3410.

In the event that a region of high permeability dries out through this mechanism, the vapor can be contained such that the entire wick does not dry out, by having multiple regions of high permeability connected by regions of low capillary radius. Then if one region of high permeability dries out, the vapor/liquid interface will be arrested at the region of low capillary radius, and therefore not spread into the adjacent region of high permeability. Because the regions of low capillary radius are porous, liquid will flow between adjacent regions of high permeability. This structure follows a similar mechanism to the method used to transport fluid up the woody structure of plants through the so-called xylem, while preventing cavitation—so this design of wick can be referred to “artificial xylem”. In some embodiments, the regions of high permeability can be formed by cutting or deforming a mesh, while the regions of low capillary radius can be formed by the un-deformed mesh; in such a manner, liquid flows between adjacent high permeability regions in-plane, as inFIG. 35AandFIG. 35B.

Some TGPs can include other wick structures (e.g. permeable wicks) that can allow in-plane low capillary radius regions and high permeability regions.FIGS. 36A and 36Billustrate a side view of at least a portion of a TGP3600with different wick structures according to some embodiments. TGP3600includes sintered particle structures3605and3610which have different densities. TGP3650with micropillars3660or microchannels with different densities, as shown inFIG. 36B; or foam structures such as inverse opals, dealloyed structures, or randomly distributed pores within a block.

FIGS. 37A and 37Billustrate a side view of at least a portion of a TGP3700with multiple regions of high permeability that may be separated by regions of low permeability. TGP3700, for example, may include in-plane impermeable walls3705, which may be connected in the through-plane direction by a permeable mesh3710, and which may allow liquid to flow between adjacent high permeable regions in the through-plane direction. In some embodiments, the high permeability regions may be defined by micropillars. In some embodiments, the impermeable walls and/or the micropillars may be formed by photolithography and/or plating or etching processes. In some embodiments, the mesh is bonded to the pillars in a thermo-sonic, thermo-compressive, or electroplating bonding method; and the second layer of micropillars and walls are grown by electroplating on the first mesh layer, as shown inFIG. 37B.

In some embodiments, the regions of high permeability may have an aspect ratio and/or angle which allows a region in one layer to connect to three or more regions in the upper or lower layer, as shown inFIG. 38. In some embodiments, there may be more than two layers that make up the through-plane stack.

In some embodiments, the mesh3710may include nano-porous scale features, with a maximum pore size of 10 nm, 50 nm 100 nm, 200 nm, etc; in some embodiments the nano-porous mesh is formed for example by track etching, by dealloying glass or metallic alloys, by nano-porous anodizing, by selective etching of self-assembled micelles, by sintering nanoparticles, etc.

FIG. 38illustrates a side view of a liquid structure of a TGP3800according to some embodiments. The TGP3800includes a liquid structure comprising a deformed mesh3810that may include any number of mesh layers. Although a deformed mesh3810is shown, any type of deformed mesh known in the art or shown in this document may be used in the liquid structure. The TGP3800may also include vapor structure that may comprise a deformed mesh3805that is deformed from a single mesh layer. In some embodiments, a planar mesh210may be disposed between the deformed mesh3810and the deformed mesh3810.

The term “permeable wick” may include one or more of a woven mesh, a nonwoven mesh, a plurality of pillars, a plurality of particles, one or meshes, a plurality of channels, a plurality of micropillars, a plurality of microchannels, etc. A permeable wick may also include foam and/or an inverse opal structure.

A term “mesh” may include a plurality of woven fibers (e.g., woven mesh) or a plurality of nonwoven fibers (a nonwoven mesh). A mesh may comprise metallic polymer fibers, metal coated polymer fibers, ceramic coated polymer fibers, ALD coated polymer fibers, copper coated steel fibers, copper coated stainless steel fibers, metal fibers, polymer fibers, copper fibers, stainless steel fibers, copper coated stainless steel, etc. A nonwoven mesh may comprise a mesh with a random distribution of fibers. A nonwoven mesh may comprise a sheet with ordered or nonordered array of holes etched in a sheet, which may be metallic or polymer. A woven mesh may comprise an ordered distribution of fibers. A nonwoven mesh may also include planar sheet formed additively such as: sintering microparticles and/or nanoparticles, electroplating through a template, rapid plating with bubble generation, deposition of metal/polymer/ceramic over a template, anodizing, etc.

Unless otherwise specified, the term “substantially” means within 5% or 10% of the value referred to or within manufacturing tolerances. Unless otherwise specified, the term “about” means within 5% or 10% of the value referred to or within manufacturing tolerances.

The conjunction “or” is inclusive.

The terms “first”, “second”, “third”, etc. are used to distinguish respective elements or blocks or steps. and are not used to denote a particular order of those elements unless otherwise specified or order is explicitly described or required.