US20150041103A1 - Vapor chamber with improved wicking structure - Google Patents

Vapor chamber with improved wicking structure Download PDF

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US20150041103A1
US20150041103A1 US14/451,905 US201414451905A US2015041103A1 US 20150041103 A1 US20150041103 A1 US 20150041103A1 US 201414451905 A US201414451905 A US 201414451905A US 2015041103 A1 US2015041103 A1 US 2015041103A1
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Prior art keywords
housing
wicking
vapor chamber
cover
base
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Abandoned
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US14/451,905
Inventor
Richard F. Kiley
Simone Bush
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AALL Power Heatsinks Inc
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AALL Power Heatsinks Inc
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Application filed by AALL Power Heatsinks Inc filed Critical AALL Power Heatsinks Inc
Priority to US14/451,905 priority patent/US20150041103A1/en
Publication of US20150041103A1 publication Critical patent/US20150041103A1/en
Abandoned legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/04Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
    • F28D15/046Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/0233Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes the conduits having a particular shape, e.g. non-circular cross-section, annular
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/34Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/42Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
    • H01L23/427Cooling by change of state, e.g. use of heat pipes

Abstract

The present invention is a vapor chamber including a housing that forms a recess within; at least one wicking structure manufactured from a bundle of wires having capillary voids therebetween that is disposed within the recess; and an amount of working fluid disposed within the recess and in fluid contact with the wicking structure such that fluid may move within the capillary voids in the wicking structures through capillary action.

Description

    CLAIM OF PRIORITY
  • This application claims the benefit of priority of United States Provisional Patent Application No. 61/862,625, filed on Aug. 6, 2013.
  • FIELD OF THE INVENTION
  • The present invention relates to vapor chambers for use in spreading heat to be dissipated and, in particular, to a vapor chamber having an improved wicking structure.
  • BACKGROUND
  • Semiconductors and other electrical components generate heat as a by-product of their operation. The generated heat can reduce or impede performance of the component if not effectively dissipated. As technology has advanced, the amount of heat to be dissipated from many of these components has risen dramatically, while the acceptable cost of heat dissipating devices has remained constant or dropped. Therefore there is a need for inexpensive products for dissipating heat that are capable of dissipating ever greater amounts of heat from an ever widening array of components and devices.
  • A heat pipe is a simple vapor chamber type heat-exchange device that can quickly transfer heat from one point to another. Heat pipes provide high thermal conductivity with small temperature differences; have a fast thermal response; are small in size and lightweight; come in a large variety of shapes; require no electrical power supply; are maintenance free; and reduce the overall system size and costs. The three basic components of a common heat pipe are a housing, a working fluid, and a wick or capillary structure. An efficient heat pipe system can be affected by the heat pipe length, the type of working fluid, the return wick type, and the number of bends in the heat pipe.
  • The housing isolates the working fluid from the outside environment. By necessity, the housing must be leak-proof, maintain the pressure differential across its walls, and enable transfer of heat to take place from and into the working fluid. Selection of the housing's fabrication material depends on many factors including compatibility; strength-to-weight ratio; thermal conductivity; ease of fabrication; porosity, etc. The housing acts to transfer heat contained within the working fluid to the outside environment.
  • Working fluids are many and varied. The prime consideration is the operating vapor temperature range. Often, several possible working fluids may exist within the approximate temperature band. Various characteristics must be examined in order to determine the most acceptable of these fluids for the application considered such as: thermal stability; compatibility with wick and wall materials; vapor pressure relative to the operating temperature range; latent heat; thermal conductivity; liquid and vapor viscosities; surface tension; and acceptable freezing or pour point. The selection of the working fluid must also be based on thermodynamic considerations that are concerned with the various limitations to heat flow occurring within the heat pipe, including viscous, sonic, capillary, entrainment, and nucleate boiling levels. Most heat pipes use water and methanol/alcohol as working fluid.
  • The typical wick is a porous structure—made of materials like steel, aluminum, nickel or copper in various pore size ranges—fabricated using metal foams, and more particularly felts, the latter being more frequently used. By varying the pressure on the felt during assembly, various pore sizes can be produced. By incorporating removable metal mandrels, an arterial structure can also be molded in the felt. The prime purpose of the wick is to generate capillary pressure to transport the working fluid from the condenser section of the housing to the evaporator section. It must also be able to distribute the liquid around the evaporator section to any area where heat is likely to be received by the heat pipe. Often these two functions require wicks of different forms. The selection of the wick for a heat pipe depends on many factors, several of which are closely linked to the properties of the working fluid.
  • In operation, one end of the heat pipe attaches to a heat source. As the heat rises to the desired operating temperature, the tube boils the working fluid and transforms it into a vapor state. As the evaporating fluid fills the hollow center of the wick, it spreads throughout the heat pipe toward to the cold end. Vapor condensation occurs wherever the temperature is even slightly below that of the evaporation area. As it condenses, the vapor releases the heat acquired during evaporation and the now-condensed working fluid then recedes back to the evaporation section. In most cases, the application must have gravity working with the system; that is, the evaporator section (heated) must be lower, with respect to gravity, than the condenser (cooling) section. When a wick structure is present in the heat pipe, the fluid recedes therein; otherwise, the fluid recedes gravimetrically. The above thermodynamic cycle continues and helps maintain constant temperatures.
  • Heat pipes are effective in a number of applications but, unfortunately, traditional heat pipes have significant drawbacks. First, although heat pipes are good at moving heat from one point to another, they are not particularly effective at spreading heat from multiple inputs on a surface. Second, the wicking structures used in heat pipes are difficult and expensive to manufacture. Finally, although heat pipes may be flattened to increase their surface area, such flattening adds to the overall cost of manufacture and reduces the effective heat dissipating capacity of the heat pipe.
  • In order to overcome the downsides of traditional heat pipes, other types of vapor chambers have been developed. One common type of vapor chamber includes a flat hollow rectangular housing into which is disposed a wicking structure and a working fluid. The wicking structure is typically a mesh type screen, metal foam, or felts that is specifically fabricated for this purpose and fills substantially all of the inside of the housing. The wicking structure allows the vapor chamber to work against gravity like a wick type heat pipe. These wicking structures are again difficult and expensive to manufacture and the use of these wicking structures limits the versatility of the layout of the heat dissipating components. Further, the use of traditional wicking structures requires the vapor chambers to be fairly thick, which limits their application.
  • Therefore, there is a need for a vapor chamber that may be easily and inexpensively manufactured, that has substantial versatility in layout of wicking structures, that may be made thinner than current vapor chambers or flattened heat pipes, and that are not limited to transferring heat from one point to another.
  • SUMMARY OF THE INVENTION
  • The present invention is a vapor chamber.
  • In its most basic form, the present invention is a vapor chamber including a housing that forms a recess within; at least one wicking structure manufactured from a bundle of wires having capillary voids therebetween that is disposed within the recess; and an amount of working fluid disposed within the recess and in fluid contact with the wicking structure such that fluid may move within the capillary voids in the wicking structures through capillary action.
  • The wicking structure preferably includes a plurality of individual wires, preferably between twenty and forty, but less than twenty or greater than forty may be included. The wicking structures are preferably made of a non-reactive metal, such as copper. Other materials out of which the wicking structures may be manufactured include aluminum, carbon fiber and certain plastics, as well as any material commonly used in the art. In some embodiments, standard off-the-shelf wire ropes may be used. The individual wires have capillary voids between the wires, within the wicking structure. These capillary voids may be three cornered or four cornered depending on the type and orientation of the wires within the bundle. The individual wires within a wicking structure are packed tightly, but not fluid tightly, so that fluid may still traverse within the capillary voids. There are also “v”-shaped vacancies between the individual wires on the surface of the wicking structures. In practice, the working fluid moves through these capillary voids and “v”-shaped vacancies toward the heat source, through capillary action. It is preferred that the wicking structures be twisted so that the distance through a capillary void or “v”-shaped vacancy from one side of the wicking structure to the other is short. More tightly twisted wire bundles will have a shorter distance than more loosely twisted wire bundles. The wires may also be braided, twisted in pairs and then aligned within the bundle, or twisted in pairs or groups and then twisted all together, for example. Herein, the term “twisted” may refer to any of these possibilities. The wicking structures may also be straight, or not twisted, but this is less effective in many applications, and therefore non-preferred. The capillary action occurs regardless of orientation of the vapor chamber and heat source relative to gravitational forces.
  • The housing is designed to fit its application, but preferably includes a base and a cover and is small and flat. The recess is formed between the base and the cover. The preferred housing is preferably substantially rectangular. Herein, “substantially rectangular” may mean that the housing is rectangular or that it may be rectangular, but with rounded corners. It is understood that some embodiments may also have a shape other than substantially rectangular. When the cover and base are united, the preferred housing is 2.5″×5″×0.125″, but may be of smaller or larger dimensions. The housing is preferably made of copper, but may be made of other materials, such as aluminum, stainless steel, nickel, or refrasil fiber. The working fluid within the recess of the housing is preferably water, but may be other working fluids, such as acetone, ammonia, methanol, or ethylene-based glycol ether products. The base and cover of the housing are preferably sealed together through welding, but may also be sealed using epoxy, screws, o-rings, gaskets, or any other method commonly used in the art.
  • In some embodiments, the inside of the housing may be sprayed or otherwise coated with polytetrafluoroethylene (“PTFE,” commonly sold under the brand name TEFLON) or other non-reactive hydrophobic materials with similar characteristics to PTFE. With such embodiments, aluminum wire structures, which traditionally have only been usable with non-water working fluids, may be used with water as the working fluid. This is a significant advantage, as water is dramatically more effective, even with the added resistance.
  • The housing may or may not be vacuum sealed. When the housing is vacuum sealed, the base of the housing may include several separators for maintaining a distance between the cover and base of the housing. The separators are small posts extending upward from the floor of the recess in the base to a height so that the cover rests on the top of the separators. The separators provide mechanical support for the cover so that it does not buckle into the recess under pressure. When the housing is not vacuum sealed, expansion may be a problem. In these embodiments, at least one, and preferably two, locations may be selected to weld the cover and base together from the outside so as to prevent the cover and base from expanding away from one another.
  • The housing preferably includes a fluid input for introducing the working fluid into the recess. The fluid input is preferably disposed within the height of the base, so that the base remains flat. The fluid input is preferably a small hole within the height of the base with a removable cap that fits snugly within the hole and prevents leakage of the working fluid when in place. The cap may be welded or otherwise permanently attached, or may be removable to allow the working fluid to be recharged. Alternatively, any art recognized means of sealing the hole may be utilized. References herein to a “side” of the housing always refer to the larger, flat sides of the cover or base of the housing. The height of the housing, which is on all four sides of the housing, will be referred to as the “height” rather than a “side,” so as to avoid confusion.
  • In operation, at least one heat source is applied to the outside of the base or cover of the housing. The wicking structures are preferably wire bundles that act as wicks so that the working fluid moves toward the heat source through the wicking structures by capillary action.
  • In a preferred embodiment, heat is absorbed on one side of the housing, either the base or the cover depending on where the heat source is located, and is emitted on the other side of the housing, therefore moving through the height of the housing. The operation of the heat chamber takes advantage of similar physical properties used with heat pipes, described, for example, in Wallin, Per. “Heat Pipe, selection of working fluid.” Project Report MVK160 Heat and Mass Transfer, 7 May 2012, hereby incorporated by reference. The traditional heat pipe generally moves heat from one end of the heat pipe to the other end. In some embodiments of the vapor chamber of the present invention, heat is moved similarly to a traditional heat pipe where the heat is moved through the length or width of the housing, rather than through the height of the housing, as described above. Distinctions between the traditional heat pipe and the vapor chamber of the present invention will be evident to one of ordinary skill in the art.
  • The preferred housing is as described above. It is understood, however, that the housing may also be of the type used traditionally with heat pipes. Heat pipe housings may take any of a variety of forms, such as sealed metal tubes. Such a heat pipe housing used in combination with the wicking structure of the present invention would have significant differences from a traditional heat pipe. Where a traditional heat pipe typically includes some sort of porous or sponge-like material as its wick, a heat pipe housing in combination with the wicking structure of the present invention would use the wicking structure as its wick. The wicking structure is unique as a wick because although the individual wire strands are not porous, the bundle of wire strands together is porous, after a fashion, in that it includes the capillary voids, and “v”-shaped vacancies, as discussed above. A heat pipe housing used in combination with a wicking structure of the present invention would also move heat via the working fluid in multiple dimensions.
  • Moreover, a traditional heat pipe typically moves heat via the working fluid from one end of the heat pipe to the other. A heat pipe housing used in combination with a wicking structure of the present invention, on the other hand, would move heat via the working fluid not only from one end of the wicking structure to the other, but also from one side of the wire bundle to the other through the twists in the wire bundle, as discussed above. A traditional tube-like heat pipe housing used in combination with a wicking structure of the present invention would preferably have twisted wire bundle wicking structures aligned around the inner surface of the tube, parallel with one another, and stretching from one end of the heat pipe to the other. In this way, the wicking structure moves heat via the working fluid from one end of the heat pipe to the other, as in a traditional heat pipe, but also from the inside cavity of the heat pipe to the outer surface of the heat pipe through the twists in the wire bundles of the wicking structure.
  • The wicking structures may be oriented within the recess in any pattern. Patterns of the wicking structures include expanding out from the middle like a star, in a big swirl, in parallel lines, or in any other configuration that makes sense considering where the heat sources will be applied to the vapor chamber.
  • If we consider the side of the vapor chamber on which a heat source is applied the “hot side” and the other side the “cold side,” liquid working fluid present in the recess of the housing will move toward the hot side through the capillary voids and “v”-shaped vacancies. On the hot side, the working fluid will evaporate and move back toward the cold side, where it will then condense and be drawn back toward the heat, et cetera. In some embodiments, some sort of additional heat sink or “cold source” may be applied to the cold side of the housing.
  • In addition to their utility as described in detail above, most embodiments of the vapor chamber of the present invention are relatively easy and inexpensive to manufacture. It is understood, however, that some embodiments may include complex machining details that may increase the ease and price of manufacture.
  • These aspects of the present invention are not meant to be exclusive and other features, aspects, and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description and accompanying drawings.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1A is a perspective view of a housing of the present invention with the cover and base separated.
  • FIG. 1B is a 40:1 magnification of the wicking structures shown in FIG. 1A.
  • FIG. 1C is a cross sectional view of the wicking structures shown in FIG. 1B.
  • FIG. 1D is a magnification of the shape of a three cornered capillary void.
  • FIG. 1E is a magnification of the shape of a four cornered capillary void.
  • FIG. 2A is a top down view of a housing of the present invention.
  • FIG. 2B is a height view of the housing shown in FIG. 2A.
  • FIG. 2C is a magnified view of section C-C shown in FIG. 2B.
  • FIG. 2D is a cross section view of the housing shown in FIG. 2A across line A-A.
  • FIG. 2E is a 4:1 magnification of section B shown in FIG. 2D.
  • FIG. 2F is a perspective view of a housing of the present invention with the cover and base separated.
  • FIG. 2G is a perspective view of a vapor chamber of the present invention.
  • FIGS. 3A-3D are perspective views of various embodiments of a vapor chamber of the present invention with the cover and base separated and different formations of the wicking structures.
  • FIGS. 4A-4J are various embodiments of the wicking structures.
  • FIG. 5A is a cutaway top down diagram showing the direction of vapor within the vapor chamber.
  • FIG. 5B is a cutaway height diagram showing the direction of heat and working fluid within the vapor chamber.
  • FIG. 6A is a cutaway top down diagram showing a vapor chamber with three heat sources.
  • FIG. 6B is a cutaway height diagram of the vapor chamber shown in FIG. 6A.
  • FIG. 7A is a cutaway top down diagram showing a vapor chamber with one heat source.
  • FIG. 7B is a cutaway height diagram of the vapor chamber shown in FIG. 7A.
  • FIG. 8A is a cutaway top down diagram showing a vapor chamber with two heat sources.
  • FIG. 8B is a cutaway height diagram of the vapor chamber shown in FIG. 8A along the short edge.
  • FIG. 8C is a cutaway height diagram of the vapor chamber shown in FIG. 8A along the long edge.
  • FIG. 9A is a cutaway top down diagram showing a vapor chamber with one heat source.
  • FIG. 9B is a cutaway height diagram of the vapor chamber shown in FIG. 9A along the short edge.
  • FIG. 9C is a cutaway height diagram of the vapor chamber shown in FIG. 9A along the long edge.
  • DETAILED DESCRIPTION
  • Referring first to FIG. 1A, a perspective view of the housing 10 of the vapor chamber of the present invention with cover 12 and base 14 separated is provided. Cover 12 mates with rim 13 of base 14. Rim 13 provides the height of housing 10 that allows for recess 11 within the housing 10. Each corner of base 14 includes a hole 18 for affixing the housing 10 in a specific place or orientation, such as with screws. Wicking structures 20 and separators 16 are disposed within the recess 11. The inclusion of separators 16 indicates that this housing 10 will be under vacuum sealing. In the embodiment shown, wicking structures 20 are spreading out from the center in a star-like pattern, but this is just one of many different patterns in which the wicking structures 10 may be oriented, as discussed in more detail below with reference to FIGS. 3A-3D. Although not shown, it is understood that a quantity of working fluid 36 will also be disposed within the recess 11 of housing 10.
  • Now referring to FIGS. 1B and 1C, 40:1 magnified views of wicking structures 20 are provided. FIG. 1B shows a portion of a wicking structure 20 from the side, along a short length of the thin individual wires 22 within the wicking structure 20. Although not apparent in other views, FIG. 1B illustrates that wires 22 are twisted within wicking structure 20. FIG. 1C shows a cross section of the wicking structure 20 including capillary voids 26 between the wires 22 within the wicking structure 20 and “v”-shaped vacancies 24 between the wires 22 on the surface of the wicking structure 20. FIG. 1E is a magnification of the shape of a three cornered capillary void 30, such as those included within wicking structure 20 shown in FIG. 1C. FIG. 1D is a magnification of the shape of a four cornered capillary void 32, shown in FIGS. 4A and 4J, for example.
  • Referring to FIG. 2A, a top down view of a housing 10 is provided. The preferred housing 10 is 2.5″ wide and 5″ long. In this view cover 12 and base 14 are united so that only cover 12, rim 13, within which cover 12 sits, and the corners of base 14 with holes 18 are visible. Referring to FIG. 2B, the height 15 of the housing 10 along the long edge is shown. The height 15 is preferably 0.125″, as indicated in FIG. 2E. FIG. 2C is a 2:1 magnification of section C-C shown in FIG. 2B. This view shows fluid input 28. Working fluid 36, which is preferably water, may be introduced to or removed from the recess 11 through fluid input 28. As evidenced by the presence of separators 16, the embodiment shown will be under vacuum. Fluid input 28 therefore must be able to seal the recess 11 airtight. One of ordinary skill in the art will recognize that the fluid input 28 shown in FIG. 2C is merely exemplary and that many variations thereof may be substituted in other embodiments. FIG. 2D is a cross sectional view of the housing 10 shown in FIG. 2A across line A-A. In this view, we see cover 12 and base 14 maintaining height 15 by separators 16. FIG. 2E is a 4:1 magnification of section B shown in FIG. 2D. In this view, we see that cover 12 is very thin and sits within rim 13 of base 14. We also see that the flat portion of base 14 is also thin like cover 12. Separators 16 provide mechanical support for the housing 10 under vacuum seal so that the cover 12 and base 14 do not buckle toward one another. Recess 11 is shown with wicking structures 20. FIGS. 2F and 2G are perspective views of the housing 10 shown in FIGS. 2A-2E with the cover 12 and base 14 separated and united, respectively.
  • Now referring to FIGS. 3A-3D, perspective views of various embodiments of the vapor chamber of the present invention are provided, with the cover 12 and base 14 separated and with different formations of wicking structures 20. FIGS. 3A and 3B show a similar pattern to that shown in FIG. 1A, with the wicking structures 20 spreading outward from the middle of the base 14. As indicated by the presence of separators 16, the housing 10 shown in FIG. 3A will be under vacuum seal. The patterns depicted in FIGS. 1A, 2F, 3A, and 3B and similar patterns where wicking structures 20 expand outward in several lines from the middle of recess 11 are referred to herein collectively as “star-like patterns.” The vapor chambers 10 shown in FIGS. 3B-3D do not include separators and therefore will not be under vacuum seal. In such embodiments, when the cover 12 and base 14 are united, the cover 12 and base 14 may be welded together in one or more locations so as to prevent them from separating due to expansion. The sealing of cover 12 and base 14 may also be effected by epoxy, screws, o-rings, gaskets, or any other method commonly used in the art. FIG. 3C shows the wicking structure 20 in a swirled pattern. The pattern depicted in FIG. 3C and similar patterns where wicking structures 20 expand outward from the middle of recess 11 in a round or spiral trajectory are referred to herein collectively as “swirl patterns.” FIG. 3D shows a combination of straight parallel wicking structures 20 and curved wicking structures 20. It is understood that wicking structures 20 that are in a straight pattern within the recess 11, such as in FIGS. 3A, 3B, and 3D, preferably still have twisted individual wires 22 within the wicking structure 20. One of ordinary skill in the art will recognize that these patterns are merely exemplary and that the wicking structures 20 may be in any pattern. The pattern is preferably determined considering the application of the vapor chamber and where a heat source 34, as shown in FIGS. 5A and 5B, for example, will be applied.
  • Now referring to FIGS. 4A-4J, various embodiments of wicking structures 20 are provided. FIGS. 4A and 4B show cross sections of wicking structures 20, with each individual wire 22 visible, as well as capillary voids 26 and “v”-shaped vacancies 24. In FIG. 4A, all wires 22 are the same size and are packed so as to include both three cornered capillary voids 30 and four cornered capillary voids 32. In FIG. 4B, a larger lead wire 22 is surrounded by smaller wires 22 twisted around it. In this embodiment, all of the capillary voids 26 are three cornered capillary voids 30. FIG. 4C shows wires 22 in a tight twist formation. FIG. 4D shows wires 22 in a loose twist formation. More tightly twisted wire structures 20, such as that shown in FIG. 4C versus FIG. 4D, have shorter capillary voids 26 from one side to the other (e.g. from the left side to the right side). Shorter capillary voids 26 provide a shorter distance for the working fluid 36 to travel. The preferred length of this distance will vary depending on the application of the vapor chamber. FIG. 4E shows wires 22 in a straight formation. FIG. 4F shows wires 22 as small twisted ropes twisted together. FIG. 4G shows wires 22 as braided ropes twisted together. Each of FIGS. 4C-4G may have wires 22 of all of the same size, as shown in FIG. 4A, or with a larger wire 22 in the middle, as shown in FIG. 4B. FIG. 4H shows wires 22 all of the same size twisted together in a loose twist similar to that shown in FIG. 4D. FIG. 4I shows wires 22 all of the same size in a straight formation similar to that shown in FIG. 4E. FIG. 4J shows wires 22 all of the same size twisted around each other or braided in several sets of pairs that are brought together to form the wicking structure 20. This embodiment is something of a hybrid of twisted and straight as the pairs of wires 22 are twisted around one another, but each pair is essentially straight. In other embodiments, the wires 22 may be both twisted around one another and twisted as a group within the wicking structure 20. Although the wicking structures 20 may be in a straight formation, as shown in FIGS. 4E and 4I, it is understood that such embodiments are non-preferred and that it is preferred that the wires 22 within wicking structure 20 be twisted, such as shown in FIGS. 4C, 4D, 4F, 4G, 4H, and 4J. The twisted formations provide a short path from the hot side of a housing 10 to the cold side. One of ordinary skill in the art will recognize that there are many ways in which the wires 22 may be arranged within the wicking structures 20, and the embodiments shown in FIGS. 4A-4J are merely exemplary.
  • Now referring to FIGS. 5A and 5B, cutaway top down and height diagrams, respectively, showing the direction of vaporous working fluid 36 within housing 10 are provided. The position of heat source 34 shown on top of housing 10 in FIG. 5B in dashed lines is also indicated in FIG. 5A in dashed lines. Regarding FIG. 5B, it is understood that the surface on which heat source 34 is being applied may be either cover 12 or base 14 of housing 10. In FIG. 5A, the arrows show the direction of the vaporous working fluid 36 moving away from heat source 34, the working fluid 36 having just absorbed heat from the heat source 34 and evaporated.
  • In FIG. 5B, the bold straight arrows show the direction of heat and the smaller squiggly arrows show the direction of the liquid working fluid 36. The small squiggly arrows show the liquid working fluid 36 moving in the “v”-shaped vacancies 24 on the surface of the wicking structure 20 between the individual wires 22. It is understood that the working fluid 36 is also moving through the capillary voids 26 within the wicking structure 20, but not visible in this view. In this way, wicking structure 20 is acting as a wick. The working fluid 36 is drawn toward the heat source 34 through capillary action. The twisted nature of the wicking structure 20 makes the distance that the working fluid has to travel from the non-heated side of the housing 10 to the side of the housing 10 on which the heat source 34 is applied very short. The twist formation of the wires 22 within the wicking structure 20 shown in FIGS. 5A and 5B is similar to that shown in FIG. 4C. One can see that if the embodiment of the wicking structure 20 shown in FIG. 4D, with a looser twist formation, were substituted, the distance the working fluid 36 would have to travel would be longer.
  • In practice, the working fluid 36 moves toward the heat source 34, as shown in FIG. 5B, through capillary action through the “v”-shaped vacancies 24 and capillary voids 26 of the wicking structure 20, acting as a wick. As the working fluid 36 approaches the heat source 34, it will evaporate and move away from the heat source 34, as shown in FIG. 5A. It will then condense on the cold side of the housing 10, or the side of the housing 10 on which the heat source 34 is not disposed. The condensation releases heat which leaves the housing 10 through the cold side, as shown in FIG. 5B. It is understood that this cycle will occur regardless of orientation of the housing 10, so that it will occur even when the capillary action of the working fluid 36 moving toward the heat source 34 is going upward or against gravity. Although not shown, in some embodiments, a cold source may be included opposite from the heat source or in a position to which it is desirable for the vaporous working fluid 36 to travel to condense.
  • Referring to FIGS. 6A and 6B, cutaway top down and height diagrams, respectively, of a housing 10 with three heat sources 34 applied to the housing 10 are provided. Referring to FIGS. 7A and 7B, cutaway top down and height diagrams, respectively, of a housing 10 with one heat source 34 applied to the housing 10 are provided. In each of these FIGS. 6A-7B, wicking structures 20 are twisted as is preferred so that the heat is moved from the hot side of the housing 10 to the cold side. These figures demonstrate that the housing 10 may operate with multiple heat sources 34 applied and with those heat sources 34 applied anywhere on the housing 10.
  • In addition to the heat moving from the hot side to the cold side of the housing 10, the heat may also move toward cooler portions of the vapor chamber along the length of the wicking structures 20. In FIG. 6A, for example, there is a relatively large space between the middle heat source 34 and the heat source 34 on the right. This relatively large space that has no heat applied to it may be relatively cool on both sides of the housing 10. Therefore, vaporous working fluid 36 moving away from those heat sources 34, in an action similar to that shown in FIG. 5A, may move through the wicking structures 20 both from one side of the vapor chamber 20 to the other through the short path created by the twists, but also along the length of the wicking structure 20 toward that space to condense on either side of the housing 10 in that space so that the housing 10 may dispel heat on both sides in that space. The vaporous working fluid 36 may also move directly through the recess 11 to get to cooler space where it will condense.
  • Referring to FIGS. 8A-8C, cutaway top down and cutaway height diagrams, respectively, of a housing 10 with two heat sources 34 are provided. Referring to FIGS. 9A-9C, cutaway top down and cutaway height diagrams, respectively, of a housing 10 with one heat source 34 are provided. These embodiments of housing 10 are more similar to traditional heat pipes than the embodiments illustrated in and described with reference to FIGS. 5A-7B. The embodiments shown in FIGS. 8A-9C are similar to heat pipes in that the heat is moved along the length of the wicking structures 20, akin to a straw, underscoring the discussion regarding FIG. 6A of the relatively large, cool space between two heat sources 34. Especially if the wicking structures 20 shown in FIGS. 8A-9C are twisted, there will still be heat moving from the hot side of the housing 10 to the cold side. The embodiments shown in FIGS. 8A-9C, however, lend themselves to wicking structures 20 where the wires 22 within the wicking structures 20 are in a straight formation, as shown in FIGS. 4E and 4I, for example. Liquid working fluid 36 will be drawn from the left of the housing 10, as shown in FIGS. 8A and 9A through the wicking structures 20, acting as wicks, toward the heat sources 34, where it will evaporate and then move away from the heat sources 34 as a gas until it condenses toward the left again and dispels the heat.
  • Comparing the patterns of the wicking structures 20 in FIGS. 6A-7B with those of FIGS. 8A-9C is illustrative to show how the vapor chamber application may determine the best wicking structure pattern. In FIGS. 6A-7B, the wicking structures 20 are twisted so that the main heat movement is going to be from the side of the housing 10 on which the heat source 34 is applied to the other side. The other side of the housing 10 therefore needs to be relatively cool so that the heat may be dispelled there. In other words, it will not work well if there is another heat source on the other side, or if there is a component that should not absorb the heat being dispelled from the housing 10 on the other side. In FIGS. 8A-9C, on the other hand, one might imagine that on the other side of the housing 10 (under the housing 10 shown in FIGS. 8C and 9C, for example) is a component that should be protected from heat or perhaps even another heat source. In such a scenario, as it is undesirable or impossible for the heat to go to the other side of the housing 10, the heat is instead directed more to the left of the housing 10. This would be facilitated by wires 22 in a straight orientation within the wicking structures 20 so that the fluid is encouraged to move more along the length of the wicking structure 20 than between the sides of the housing 10, as it would be with a twisted wicking structure 20.
  • Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions would be readily apparent to those of ordinary skill in the art. Therefore, the spirit and scope of the description should not be limited to the description of the preferred versions contained herein.

Claims (20)

We claim:
1. A vapor chamber comprising:
a housing;
a recess within said housing;
at least one wicking structure disposed within said recess, wherein:
said at least one wicking structure comprises a plurality of individual wires;
capillary voids are formed between said plurality of wires within said at least one wicking structure; and
v-shaped vacancies are formed between said plurality of wires on a surface of said at least one wicking structure; and
an amount of working fluid disposed within said recess and in fluid contact with said at least one wicking structure such that said working fluid is capable of moving through said capillary voids and said v-shaped vacancies of said at least one wicking structure through capillary action.
2. The vapor chamber as claimed in claim 1, wherein said capillary voids are shaped as one of a group consisting of three cornered and four cornered.
3. The vapor chamber as claimed in claim 1, wherein said plurality of individual wires are twisted.
4. The vapor chamber as claimed in claim 1, wherein said housing comprises a base, a cover and a seal disposed between said base and said cover and, wherein said base and said cover are removable attached.
5. The vapor chamber as claimed in claim 1, wherein an interior of said housing and each of said wires is coated with polytetrafluoroethylene, and wherein said working fluid is water.
6. The vapor chamber as claimed in claim 1, wherein said working fluid is water.
7. The vapor chamber as claimed in claim 1, wherein said housing is vacuum sealed and said vapor chamber further comprises at least one separator disposed within said recess between said cover and said base so as to maintain a separation between said cover and said base while said housing is under vacuum.
8. The vapor chamber as claimed in claim 1, wherein at least one location on said housing, said cover and said base are affixed together so as to prevent expansion of said cover and said base away from one another.
9. The vapor chamber as claimed in claim 1, further comprising a fluid input disposed on said housing, wherein said fluid input allows for deposit of said working fluid into said recess.
10. The vapor chamber as claimed in claim 1, wherein said at least one wicking structure is disposed within said recess in a star-like pattern, expanding outward from a middle of said recess.
11. The vapor chamber as claimed in claim 1, wherein said at least one wicking structure is disposed within said recess in a swirled pattern
12. The vapor chamber as claimed in claim 1, wherein said plurality of individual wires comprises wires all of the same size.
13. The vapor chamber as claimed in claim 1, wherein said plurality of individual wires comprises one larger wire surrounded by a plurality of smaller wires.
14. A vapor chamber comprising:
a housing comprising a base, a cover, and a recess formed between said base and said cover; and
at least one wicking structure disposed within said recess, wherein:
said at least one wicking structure comprises at least three individual wires; and
capillary voids are formed between said wires within said at least one wicking structures; and
an amount of working fluid disposed within said recess and in fluid contact with said at least one wicking structure such that said working fluid is capable of moving through said capillary voids through capillary action.
15. The vapor chamber as claimed in claim 14, wherein an interior of said housing and each of said at least three wires are coated with polytetrafluoroethylene and wherein said working fluid is water.
16. The vapor chamber as claimed in claim 14, wherein said housing is vacuum sealed and said vapor chamber further comprises at least one separator disposed within said recess between said cover and said base so as to maintain a separation between said cover and said base while said housing is under vacuum.
17. The vapor chamber as claimed in claim 14, wherein at least one location on said housing, said cover and said base are affixed together so as to prevent expansion of said cover and said base away from one another.
18. A vapor chamber system comprising:
a vapor chamber comprising:
a housing comprising a base and a cover;
a recess formed between said base and said cover when said base and said cover are united;
at least one wicking structure disposed within said recess, wherein:
said at least one wicking structure comprises a plurality of individual wires;
capillary voids are formed between said wires within said at least one wicking structures; and
v-shaped vacancies are formed between said wires on a surface of said at least one wicking structure; and
an amount of working fluid disposed within said recess and in fluid contact with said at least one wicking structure such that said working fluid is capable of moving through said capillary voids and said v-shaped vacancies through capillary action; and
at least one heat source disposed proximate to one of said base and said cover of said housing of said vapor structure such that heat from said at least one heat source is transferred through said housing into said working fluid disposed within said housing.
19. The vapor chamber system as claimed in claim 18, further comprising at least one cold source disposed at a different position proximate to one of said base and said cover of said housing of said vapor structure than said at least one heat source, such that heat from said working fluid disposed within said housing is transferred from said heat source through said housing into said at least one cold source.
20. The vapor chamber system as claimed in claim 19, wherein said at least one wicking structure is disposed within said recess of said housing of said vapor chamber such that:
a portion of said at least one wicking structure is proximate to said at least one heat source such that said working fluid in fluid contact with said at least one wicking structure evaporates and moves away from said at least one heat source through said capillary voids and v-shaped vacancies in said at least one wicking structure; and
a portion of said at least one wicking structure is far enough away from said at least one heat source and any other heat source such that said working fluid that evaporated near said at least one heat source and moved away from said at least one heat source through said capillary voids and v-shaped vacancies condenses.
US14/451,905 2013-08-06 2014-08-05 Vapor chamber with improved wicking structure Abandoned US20150041103A1 (en)

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US20120018130A1 (en) * 2010-07-21 2012-01-26 Asia Vital Components Co., Ltd. Thermal siphon structure
US20160123679A1 (en) * 2014-10-30 2016-05-05 Foxconn Technology Co., Ltd. Woven fibers, wick structures having the woven fibers and heat pipes having the wick structures
CN106767068A (en) * 2016-11-29 2017-05-31 上海卫星工程研究所 A kind of slim vapor chamber
US20190035713A1 (en) * 2017-07-28 2019-01-31 Qualcomm Incorporated Systems and methods for cooling an electronic device
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US20050051304A1 (en) * 2002-12-12 2005-03-10 Sony Corporation Heat transport device and electronic device
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Publication number Priority date Publication date Assignee Title
US20120018130A1 (en) * 2010-07-21 2012-01-26 Asia Vital Components Co., Ltd. Thermal siphon structure
US9074823B2 (en) * 2010-07-21 2015-07-07 Asia Vital Components Co., Ltd. Thermal siphon structure
US20160123679A1 (en) * 2014-10-30 2016-05-05 Foxconn Technology Co., Ltd. Woven fibers, wick structures having the woven fibers and heat pipes having the wick structures
CN106767068A (en) * 2016-11-29 2017-05-31 上海卫星工程研究所 A kind of slim vapor chamber
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US10622282B2 (en) * 2017-07-28 2020-04-14 Qualcomm Incorporated Systems and methods for cooling an electronic device
EP3671095A1 (en) * 2018-12-21 2020-06-24 Cooler Master Co., Ltd. Heat dissipation device having irregular shape

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