Heat diffusing device, electronic apparatus, and wick for heat diffusing device

Abstract

A heat diffusing device (1) comprises: a housing (10) which has a first inner surface (11a) and a second inner surface (12a) facing each other in the thickness direction, and which is provided with an inner space; a working medium (20) which is sealed in the inner space of the housing (10); and a sheet-like wick (30) which is disposed in the inner space of the housing (10). The wick (30) has, in at least a part thereof, a plurality of first through holes (61) passing therethrough in the thickness direction and a plurality of second through holes (62) passing therethrough in the thickness direction. A first projection part (71) which projects in a direction approaching the first inner surface (11a) is provided at the circumference of each of the first through holes (61). A second projection part (72) which projects in a direction approaching the second inner surface (12a) is provided at the circumference of each of the second through holes (62). In the thickness direction, the distance between the wick (30) and the first inner surface (11a) is less than the distance between the wick (30) and the second inner surface (12a). The number of the second through holes (62) per unit area of the wick (30) viewed in the thickness direction is greater than the number of the first through holes (61) per unit area of said wick.

Description

Heat spreading device, electronic device and wick for heat spreading device

[0001] The present invention relates to heat spreading devices, electronic devices and wicks for heat spreading devices.

[0002] In recent years, the amount of heat generated has increased due to the high integration and high performance of elements. Furthermore, as products become more compact, the heat density increases, making heat dissipation measures important. This situation is particularly evident in the field of mobile devices such as smartphones and tablets. Graphite sheets are often used as thermal management materials, but their heat transport capacity is insufficient, so the use of various thermal management materials is being considered. Among these, the use of vapor chambers, which are planar heat pipes, is being considered as a heat diffusion device that can diffuse heat very effectively.

[0003] The vapor chamber has a structure in which a working medium (also called a working liquid) and a wick that transports the working medium by capillary force are enclosed inside a housing. The working medium absorbs heat from a heat-generating element such as an electronic component in an evaporation section, evaporates in the vapor chamber, moves within the vapor chamber, cools, and returns to its liquid phase. The working medium, which has returned to its liquid phase, moves again to the evaporation section on the heating element side by the capillary force of the wick, cooling the heating element. By repeating this process, the vapor chamber operates autonomously without external power and can diffuse heat two-dimensionally at high speed using the latent heat of evaporation and latent heat of condensation of the working medium.

[0004] Patent Document 1 discloses a vapor chamber comprising: a housing having an internal space, including opposing upper and lower housing sheets joined at their outer edges; a working fluid sealed in the internal space; a microchannel disposed in the internal space of the lower housing sheet and constituting a flow path for the working fluid; and a sheet-like wick disposed in the internal space of the housing and in contact with the microchannel, wherein the contact area between the wick and the microchannel is 5% to 40% of the area of ​​the internal space when viewed in plan.

[0005] International Publication No. 2021 / 229961

[0006] In the vapor chamber described in Patent Document 1, the working fluid that has released heat and returned to liquid form in the internal space of the housing moves through the microchannels due to the capillary force of the wick holes and is transported back to the vicinity of the heat source. However, if there is insufficient adhesion between the wick placed in the internal space of the housing and the convex portions of the microchannels formed in the lower housing sheet, the liquid working fluid will be difficult to transport to the vicinity of the heat source, which may reduce the maximum heat transport capacity of the vapor chamber.

[0007] The above problem is not limited to vapor chambers, but is a common problem with heat diffusion devices that can diffuse heat with a similar configuration to a vapor chamber.

[0008] The present invention has been made to solve the above problems, and aims to provide a heat spreading device with a large heat transfer rate. Another aim of the present invention is to provide an electronic device equipped with the heat spreading device, and a wick for the heat spreading device.

[0009] The heat diffusion device of the present invention comprises a housing having a first inner surface and a second inner surface opposed to each other in a thickness direction and having an internal space, a working medium sealed in the internal space of the housing, and a sheet-like wick arranged in the internal space of the housing, wherein the wick has, in at least a portion thereof, a plurality of first through holes penetrating in the thickness direction and a plurality of second through holes penetrating in the thickness direction, the periphery of the first through holes being provided with a first convex portion protruding in a direction approaching the first inner surface, and the periphery of the second through holes being provided with a second convex portion protruding in a direction approaching the second inner surface, the distance between the wick and the first inner surface in the thickness direction is smaller than the distance between the wick and the second inner surface, and the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

[0010] An electronic device of the present invention includes the heat spreading device of the present invention.

[0011] The wick for a heat diffusion device of the present invention is a sheet-like wick having, at least in part, a plurality of first through holes penetrating in the thickness direction and a plurality of second through holes penetrating in the thickness direction, wherein the periphery of the first through holes is provided with a first convex portion protruding in one direction in the thickness direction, and the periphery of the second through holes is provided with a second convex portion protruding in the opposite direction to the thickness direction, and the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

[0012] According to the present invention, a heat diffusion device having a large heat transport capacity can be provided. Furthermore, according to the present invention, an electronic device including the heat diffusion device and a wick for the heat diffusion device can be provided.

[0013] FIG. 1 is a perspective view schematically showing an example of a heat diffusing device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a heat diffusing device according to the first embodiment of the present invention. FIG. 3 is a perspective view schematically showing an example of a wick constituting the heat diffusing device according to the first embodiment of the present invention. FIG. 4 is a plan view of the wick shown in FIG. 3. FIG. 5 is a cross-sectional view of the wick shown in FIG. 4 taken along line A-A. FIG. 6 is a cross-sectional view of the wick shown in FIG. 4 taken along line B-B. FIG. 7 is a cross-sectional view schematically showing an example of a heat diffusing device at a position different from that shown in FIG. 2. FIG. 8 is a cross-sectional view schematically showing an example of the shape of the second protrusion. FIG. 9 is a cross-sectional view schematically showing another example of the shape of the second protrusion. FIG. 10 is a plan view schematically showing another example of a wick constituting the heat diffusing device according to the first embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing an example of a heat diffusing device according to a second embodiment of the present invention. FIG. 12 is a perspective view schematically showing an example of a heat diffusing device according to a third embodiment of the present invention. FIG. 13 is a cross-sectional view schematically showing an example of a heat diffusing device according to the third embodiment of the present invention.

[0014] The heat spreading device of the present invention will be described below. However, the present invention is not limited to the following embodiments, and can be modified as appropriate within the scope of the present invention. Note that a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0015] The heat diffusion device of the present invention may be, for example, a planar vapor chamber or a tubular heat pipe.

[0016] The wick for the heat diffusion device described below also constitutes the present invention.

[0017] The following embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description of the matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0018] In the following description, unless otherwise specified, each embodiment will be simply referred to as the "heat spreading device of the present invention."

[0019] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and other scales may differ from those of the actual product. In the drawings, the same or equivalent parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and duplicate explanations will be omitted.

[0020] In this specification, terms indicating the relationship between elements (e.g., "perpendicular," "parallel," "orthogonal," etc.) and terms indicating the shapes of elements are not expressions that only express a strict meaning, but are expressions that mean that a range of substantial equivalence, for example, a difference of about a few percent, is also included. Furthermore, in this specification, "equivalent" or "constant" is not an expression that means only completely equivalent or constant, but is an expression that means that a range of substantial equivalence or constant, for example, a difference of about a few percent, is also included.

[0021] [First embodiment] Fig. 1 is a perspective view schematically showing an example of a heat diffusion device according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of a heat diffusion device according to the first embodiment of the present invention. Fig. 2 is an example of a cross-sectional view taken along line II-II of the heat diffusion device shown in Fig. 1.

[0022] The vapor chamber (heat diffusion device) 1 shown in Figures 1 and 2 includes a hollow housing 10 that is sealed in an airtight state. The housing 10 has a first inner surface 11a and a second inner surface 12a that face each other in the thickness direction Z. The housing 10 has an internal space. The vapor chamber 1 further includes a working medium 20 sealed in the internal space of the housing 10 and a sheet-like wick 30 disposed in the internal space of the housing 10. The vapor chamber 1 may further include a support 40 disposed in the internal space of the housing 10.

[0023] The housing 10 is provided with an evaporation section that evaporates the enclosed working medium 20. As shown in Fig. 1, a heat source HS, which is a heat generating element, is disposed on the outer surface of the housing 10. Examples of the heat source HS include electronic components of an electronic device, such as a central processing unit (CPU). The portion of the interior space of the housing 10 that is near the heat source HS and that is heated by the heat source HS corresponds to the evaporation section.

[0024] The vapor chamber 1 is preferably planar as a whole. That is, the housing 10 is preferably planar as a whole. Here, "planar" includes plate-like and sheet-like shapes, and refers to a shape in which the dimension in the width direction X (hereinafter referred to as width) and the dimension in the length direction Y (hereinafter referred to as length) are considerably larger than the dimension in the thickness direction Z (hereinafter referred to as thickness or height), for example, a shape in which the width and length are 10 times or more, preferably 100 times or more, the thickness.

[0025] The size of the vapor chamber 1, i.e., the size of the housing 10, is not particularly limited. The width and length of the vapor chamber 1 can be set appropriately depending on the application. The width and length of the vapor chamber 1 are, for example, 5 mm or more and 500 mm or less, 20 mm or more and 300 mm or less, or 50 mm or more and 200 mm or less. The width and length of the vapor chamber 1 may be the same or different.

[0026] The housing 10 is preferably constructed from a first sheet 11 and a second sheet 12 facing each other and joined at their outer edges.

[0027] When the housing 10 is composed of the first sheet 11 and the second sheet 12, the material that constitutes the first sheet 11 and the second sheet 12 is not particularly limited as long as it has properties suitable for use as a heat diffusion device such as a vapor chamber, such as thermal conductivity, strength, flexibility, and the like. The material that constitutes the first sheet 11 and the second sheet 12 is preferably a metal, such as copper, nickel, aluminum, magnesium, titanium, iron, or an alloy containing these as a main component, with copper being particularly preferred. The materials that constitute the first sheet 11 and the second sheet 12 may be the same or different, but are preferably the same.

[0028] When the housing 10 is composed of the first sheet 11 and the second sheet 12, the first sheet 11 and the second sheet 12 are joined to each other at their outer edges. The joining method is not particularly limited, but may be, for example, laser welding, resistance welding, diffusion bonding, brazing, TIG welding (tungsten-inert gas welding), ultrasonic bonding, or resin sealing, and preferably, laser welding, resistance welding, or brazing.

[0029] The thickness of the first sheet 11 and the second sheet 12 is not particularly limited, but is preferably 10 μm or more and 200 μm or less, more preferably 30 μm or more and 100 μm or less, and even more preferably 40 μm or more and 60 μm or less. The thickness of the first sheet 11 and the second sheet 12 may be the same or different. Furthermore, the thickness of each of the first sheet 11 and the second sheet 12 may be the same throughout, or may be thinner in some areas.

[0030] There are no particular limitations on the shapes of the first sheet 11 and the second sheet 12. For example, the first sheet 11 and the second sheet 12 may each have a shape in which the outer edge portion is thicker than the portion other than the outer edge portion.

[0031] The thickness of the entire vapor chamber 1 is not particularly limited, but is preferably 50 μm or more and 500 μm or less. The height of the internal space of the housing 10 is not particularly limited, but is preferably 30 μm or more and 400 μm or less.

[0032] The planar shape of the housing 10 as viewed from the thickness direction Z is not particularly limited, and examples thereof include polygons such as triangles or rectangles, circles, ellipses, and combinations thereof. The planar shape of the housing 10 may also be L-shaped, C-shaped, stepped, or the like. The housing 10 may also have a through-hole. The planar shape of the housing 10 may be a shape that corresponds to the application of the heat diffusion device, such as a vapor chamber, the shape of the location where the heat diffusion device is installed, and other components present nearby.

[0033] The working medium 20 is not particularly limited as long as it can undergo a gas-liquid phase change in the environment inside the housing 10, and examples of the working medium that can be used include water, alcohols, and alternatives to chlorofluorocarbons. For example, the working medium 20 is an aqueous compound, and is preferably water.

[0034] The wick 30 has a capillary structure that allows the working medium 20 to move by capillary force.

[0035] The material constituting the wick 30 is not particularly limited, but is preferably a metal, such as copper, nickel, aluminum, magnesium, titanium, iron, or an alloy containing these as a main component, and is particularly preferably copper. The material constituting the wick 30 may be the same as or different from the material constituting the housing 10.

[0036] The material constituting the wick 30 may be porous. When the wick 30 is made of a porous material, the surface area of ​​the wick 30 increases, thereby increasing the area of ​​the evaporation surface, where the working medium evaporates. Examples of porous materials include porous metal membranes formed by etching or metal processing, meshes, nonwoven fabrics, sintered bodies, and other porous materials. The mesh may be, for example, a metal mesh, a resin mesh, or a surface-coated version of such a mesh, and is preferably made of copper mesh, stainless steel mesh, or polyester mesh. The sintered body may be, for example, a porous metal sintered body or a porous ceramic sintered body, and is preferably a porous copper or nickel sintered body. Other porous materials include, for example, porous metals, porous ceramics, and porous resins. Meshes, nonwoven fabrics, and sintered bodies are also included in the porous material in this specification.

[0037] The size and shape of the wick 30 are not particularly limited as long as it is sheet-shaped, but for example, it is preferable that the wick 30 is arranged continuously in the internal space of the housing 10. When viewed from the thickness direction Z, the wick 30 may be arranged throughout the entire internal space of the housing 10, or when viewed from the thickness direction Z, the wick 30 may be arranged in a portion of the internal space of the housing 10.

[0038] 2, a support 40 that contacts the second inner surface 12a may be disposed in the internal space of the housing 10. By disposing the support 40 in the internal space of the housing 10, it is possible to support the housing 10 and the wick 30.

[0039] The material constituting the support 40 is not particularly limited, but examples thereof include resin, metal, ceramic, or a mixture or laminate thereof. Furthermore, the support 40 may be integral with the housing 10 as shown in Fig. 2, or may be formed by, for example, etching the second inner surface 12a of the housing 10.

[0040] The shape of the support 40 is not particularly limited as long as it can support the housing 10 and the wick 30, but examples of the cross-sectional shape perpendicular to the height direction of the support 40 include polygons such as rectangles, circles, ellipses, etc.

[0041] 2, the support pillars 40 may have a tapered shape that narrows from the second inner surface 12a of the housing 10 toward the wick 30. This allows the flow path between the support pillars 40 to be wider on the wick 30 side.

[0042] Fig. 3 is a perspective view schematically showing an example of a wick constituting the heat spreading device according to the first embodiment of the present invention, and Fig. 4 is a plan view of the wick shown in Fig. 3.

[0043] At least a portion of the sheet-like wick 30 includes a first through hole 61 penetrating in the thickness direction Z and a second through hole 62 penetrating in the thickness direction Z. The first through hole 61 and the second through hole 62 are collectively referred to simply as through holes.

[0044] The first through-holes 61 and the second through-holes 62 can be formed, for example, by punching the metal foil that constitutes the wick 30 using a press process.

[0045] The working medium 20 can move in the first through hole 61 and the second through hole 62 by capillary action. The shapes of the first through hole 61 and the second through hole 62 are not particularly limited, but it is preferable that the cross section in a plane perpendicular to the thickness direction Z is circular or elliptical. The shape of the first through hole 61 and the shape of the second through hole 62 may be the same as or different from each other.

[0046] In the wick 30 shown in Fig. 4, the first through holes 61 and the second through holes 62 are arranged in a staggered arrangement. However, the first through holes 61 and the second through holes 62 are not alternately arranged, but rather half of the first through holes 61 are replaced with second through holes 62, rather than being alternately arranged. Specifically, based on a staggered arrangement in which a row α of through holes in which only second through holes 62 are arranged along the width direction X and a row β of through holes in which only first through holes 61 are arranged along the width direction X, the row β is alternately arranged in the positive direction of the length direction Y, and every other first through hole 61 constituting the row β is replaced with a second through hole 62, so that the row β １ or column β ２ Note that the row β of through holes in which only the first through holes 61 are arranged along the width direction X before every other first through hole 61 constituting the row β is changed to the second through hole 62 is not shown in FIG.

[0047] For example, in the row of through holes arranged at a position overlapping with the line A-A, the first through holes 61 and the second through holes 62 are arranged alternately along the width direction X. Therefore, the row of through holes arranged at a position overlapping with the line A-A is called row β １ In addition, in the row of through holes arranged at a position overlapping with line B-B, only the second through holes 62 are arranged along the width direction X. Therefore, the row of through holes arranged at a position overlapping with line B-B is row α.

[0048] Similarly, the row β of through holes arranged at a position overlapping with the line A-A １ The row of through holes adjacent to the row α in the negative direction of the length direction Y is row α in which only the second through holes are arranged along the width direction X. Furthermore, the row of through holes adjacent to the row α in the positive direction of the length direction Y, which is arranged at a position overlapping with the line B-B, is row β in which the first through holes 61 and the second through holes 62 are arranged alternately along the width direction X. １ The arrangement of the first through holes 61 and the second through holes 62 is different. ２ is.

[0049] With the row α of through holes arranged at a position overlapping the line B-B as a reference, the row of through holes adjacent in the positive direction of the longitudinal direction Y is row β ２Further, the row of through holes adjacent to each other in the positive direction of the longitudinal direction Y is row α, and the row of through holes adjacent to each other in the positive direction of the longitudinal direction Y is row β. １ Furthermore, the row of through holes adjacent in the positive direction of the length direction Y is row α. That is, in the wick 30 shown in FIG. 4, four types of rows of through holes extending in the width direction X (row α, row β ２ , column α and column β １ ) are repeatedly arranged in the length direction Y.

[0050] When the rows α and β are alternately arranged in the longitudinal direction Y, the number of the first through holes 61 and the number of the second through holes 62 per unit area of ​​the wick are equal. However, as described above, the row β has a different number of first through holes 61 than the row β in which half of the first through holes 61 are replaced with second through holes 62. １ or column β ２ 4 , the number of first through holes 61 is reduced to half of that in the above-described case, and the reduction in the number of first through holes 61 is equal to the increase in the number of second through holes 62. That is, in the wick 30 shown in FIG. 4 , the ratio of the number of first through holes to the number of second through holes per unit area is 1:3. Therefore, the number of second through holes 62 per unit area of ​​the wick 30 when viewed from the thickness direction is greater than the number of first through holes 61 per unit area. When the number of second through holes per unit area is greater than the number of first through holes, the wick 30 has many convex structures on the second inner surface 12a side of the housing 10, which is the evaporation surface side, and therefore the evaporation surface is increased, improving heat transport efficiency.

[0051] The arrangement of the first through holes 61 and the second through holes 62 in the wick 30 is not limited to the above arrangement. For example, a wick that constitutes the heat diffusion device of the present invention may be formed by replacing some randomly selected first through holes 61 with second through holes 62 in a staggered arrangement in which the first through holes 61 and the second through holes 62 are alternately arranged.

[0052] The number of second through holes 62 per unit area is preferably 150% or more and 500% or less of the number of first through holes 61 per unit area.

[0053] FIG. 5 is a cross-sectional view of the wick shown in FIG. 4 taken along line AA.

[0054] As shown in FIG. 5 , at a position overlapping line A-A of the wick, first through holes 61 and second through holes 62 are alternately arranged along the width direction X. Note that FIG. 5 shows the row of through holes arranged at a position overlapping line A-A up to the row of through holes adjacent in the positive direction of the length direction Y, and omits through holes arranged further back (on the positive side of the length direction Y). A first protrusion 71 protruding in one direction in the thickness direction (the negative direction of the thickness direction Z in FIG. 5 ) is provided on the periphery of the first through hole 61. In the example shown in FIG. 2 , in the vapor chamber 1, the first protrusion 71 protrudes in a direction approaching the first inner surface 11a.

[0055] By providing a first convex portion 71 on the periphery of the first through hole 61, in the vapor chamber 1 shown in Figure 2, a liquid flow path through which the liquid working medium 20 moves is formed between the wick 30 and the first inner surface 11a of the housing 10.

[0056] Unlike Patent Document 1, the first protrusions 71 are integrally formed with the wick 30, so that adhesion with the wick 30 does not decrease. Therefore, the maximum heat transport amount can be improved compared to Patent Document 1. Furthermore, because the first protrusions 71 can form a liquid flow path, it is not necessarily necessary to form a microchannel by processing the first inner surface 11a of the housing 10 as in Patent Document 1.

[0057] The first convex portion 71 may or may not be in contact with the first inner surface 11 a of the housing 10. When the first convex portion 71 is in contact with the first inner surface 11 a, the first convex portion 71 may or may not be bonded to the first inner surface 11 a.

[0058] The wick 30 includes a plurality of first through holes 61, each having a periphery provided with a first protrusion 71. The first protrusion 71 may be provided only on a portion of the periphery of the first through hole 61, but is preferably provided on the entire periphery of the first through hole 61. As shown in Fig. 5 , the periphery of the second through hole 62 is provided with a second protrusion 72 that protrudes in the opposite direction of the thickness direction (the positive direction of the thickness direction Z in Fig. 5 ).

[0059] Fig. 6 is a cross-sectional view of the wick taken along line B-B in Fig. 4. Fig. 6 shows the row of through-holes arranged at a position overlapping line B-B up to the row of through-holes adjacent in the positive direction of the length direction Y, and omits through-holes arranged further back (on the positive side of the length direction Y). Fig. 7 is a cross-sectional view schematically showing an example of a heat diffusion device at a position different from that shown in Fig. 2.

[0060] As shown in Fig. 6, a second protrusion 72 protruding in the opposite direction of the thickness direction (the positive direction of the thickness direction Z in Fig. 6) is provided on the periphery of the second through hole 62. In the example shown in Fig. 7, in the vapor chamber 1, the second protrusion 72 protrudes in a direction approaching the second inner surface 12a.

[0061] 7, a vapor space through which the vapor of the working medium 20 moves is formed between the wick 30 and the second inner surface 12a of the housing 10. At this time, the second through-holes 62, which have second protrusions 72 provided on their peripheries, allow the vaporized working medium 20 to move efficiently into the vapor space.

[0062] 2 and 7, the distance between the wick 30 and the first inner surface 11a in the thickness direction Z is smaller than the distance between the wick 30 and the second inner surface 12a. With the above configuration, the space between the wick 30 and the first inner surface 11a, where the relative distance is smaller, serves as a liquid flow path, and the space between the wick 30 and the second inner surface 12a, where the relative distance is larger, serves as a vapor flow path. This makes it possible to form a liquid flow path while ensuring a sufficient vapor space (vapor flow path).

[0063] When the support 40 is disposed in the internal space of the housing 10, the second convex portion 72 may or may not be in contact with the support 40. When the second convex portion 72 is in contact with the support 40, the second convex portion 72 may or may not be joined to the support 40.

[0064] 7, when the second protrusion 72 is in contact with the support 40, a space (the area indicated by P in FIG. 7) exists between the wick 30 and the support 40. This space P can be used as a vapor flow path through which the vapor of the working medium 20 moves, and therefore the heat transport capacity of the vapor chamber 1 can be increased compared to when the second protrusion 72 is not provided.

[0065] The wick 30 includes a plurality of second through holes 62 each having a periphery provided with a second protrusion 72. The second protrusion 72 may be provided only on a portion of the periphery of the second through hole 62, but is preferably provided on the entire periphery of the second through hole 62.

[0066] The first convex portions 71 and the second convex portions 72 can be formed, for example, by punching the metal foil that constitutes the wick 30 using a press process. In this case, the first convex portions 71 may be formed simultaneously with the first through holes 61, or may be formed separately from the first through holes 61. Similarly, the second convex portions 72 may be formed simultaneously with the second through holes 62, or may be formed separately from the second through holes 62. In punching using a press process, the shapes of the first convex portions 71 and the second convex portions 72 can be adjusted by appropriately adjusting the punching depth, etc. Note that the punching depth refers to, for example, how far the punch is pressed in the punching direction when punching with a punch.

[0067] The shape of the second convex portion 72 is not particularly limited.

[0068] FIG. 8 is a cross-sectional view schematically showing an example of the shape of the second convex portion.

[0069] As shown in Fig. 8 , the distance between the outer walls of the second convex portions 72 may decrease toward the tip of the second convex portion 72 (toward the upper side in Fig. 8 ). That is, the second convex portions 72 may have a tapered shape. In this case, the second convex portions 72 may have a shape that is convex toward the tip side of the second convex portion 72 (upper side in Fig. 8 ) or toward the base end side of the second convex portion 72 (lower side in Fig. 8 ) in a cross section along the thickness direction.

[0070] FIG. 9 is a cross-sectional view schematically showing another example of the shape of the second convex portion.

[0071] As shown in FIG. 9 , the second protrusion 72 may have a lid portion at the tip that narrows the second through-hole 62 .

[0072] When the second convex portion 72 has a tapered shape, in the example shown in Figure 2, if the distance between the outer walls of the second convex portion 72 narrows toward the second inner surface 12a of the housing 10, the pressure loss in the steam flow path can be reduced.

[0073] Although not shown, the distance between the outer walls of the second convex portion 72 may increase toward the tip of the second convex portion 72. That is, the second convex portion 72 may have an inverse tapered shape. In this case, the second convex portion 72 may have a shape that is convex toward the tip side of the second convex portion 72 or toward the base end side of the second convex portion 72 in a cross section along the thickness direction. The second convex portion 72 may have a lid portion at its tip that narrows the second through hole 62.

[0074] Alternatively, the distance between the outer walls of the second protrusions 72 may be constant toward the tip of the second protrusions 72. In this case, the second protrusions 72 may have a lid portion at the tip that narrows the second through-hole 62.

[0075] Similarly, the shape of the first convex portion 71 is not particularly limited.

[0076] For example, the distance between the outer walls of the first convex portion 71 may decrease toward the tip of the first convex portion 71. That is, the first convex portion 71 may have a tapered shape. In this case, the first convex portion 71 may have a shape that is convex toward the tip side of the first convex portion 71 or toward the base end side of the first convex portion 71 in a cross section along the thickness direction. The first convex portion 71 may have a lid portion at its tip that narrows the first through hole 61.

[0077] When the first convex portion 71 has a tapered shape, in the example shown in Figure 7, if the distance between the outer walls of the first convex portion 71 narrows toward the first inner surface 11a of the housing 10, the pressure loss in the liquid flow path can be reduced.

[0078] Furthermore, the distance between the outer walls of the first convex portion 71 may increase toward the tip of the first convex portion 71. That is, the first convex portion 71 may have an inverse tapered shape. In this case, the first convex portion 71 may have a shape that is convex toward the tip side of the first convex portion 71 or toward the base end side of the first convex portion 71 in a cross section along the thickness direction. The first convex portion 71 may have a lid portion at its tip that narrows the first through hole 61.

[0079] Alternatively, the distance between the outer walls of the first convex portion 71 may be constant toward the tip of the first convex portion 71. In this case, the first convex portion 71 may have a lid portion at the tip that narrows the first through hole 61.

[0080] The diameter of the first through hole 61, the periphery of which is provided with the first protrusion 71, is not particularly limited, but is, for example, 5 μm or more and 100 μm or less. Note that, when the diameter of the first through hole 61 varies in the thickness direction Z, the diameter of the smallest portion is defined as the diameter of the first through hole 61.

[0081] The diameter of the second through hole 62, the periphery of which is provided with the second protrusion 72, is not particularly limited, but is, for example, 5 μm or more and 100 μm or less. Note that, when the diameter of the second through hole 62 varies in the thickness direction Z, the diameter of the smallest portion is defined as the diameter of the second through hole 62.

[0082] The diameter of the first through hole 61 and the diameter of the second through hole 62 may be the same or different, but it is preferable that the diameter of the first through hole 61 and the diameter of the second through hole 62 are the same.

[0083] 4 and other figures, the wick 30 includes a plurality of first through holes 61. The shapes, diameters, etc. of the plurality of first through holes 61 may be the same or different.

[0084] The arrangement of the first through holes 61 is not particularly limited, but for example, it is preferable that the center-to-center distance (pitch) of the two closest first through holes 61 is arranged so that the minimum and maximum values ​​are 90% or more and 110% or less of the average value, respectively, and more preferably, they are arranged so that all are equal. When the center-to-center distances (pitch) of the two closest first through holes 61 are all equal, it can be said that the center-to-center distance (pitch) of the two closest first through holes 61 is constant. It is preferable that the center-to-center distance (pitch) of the two closest first through holes 61 is constant in a predetermined region of the wick 30, and more preferably, it is constant throughout the entire wick 30.

[0085] When the center-to-center distance between the two closest first through holes 61 is constant, the liquid working medium 20 can be spread uniformly on the surface viewed from the thickness direction Z. Therefore, the characteristics of the vapor chamber 1 can be made uniform.

[0086] The center-to-center distance between the two closest first through holes 61 is not particularly limited, but is, for example, not less than 60 μm and not more than 300 μm.

[0087] 4 and other figures, the wick 30 includes a plurality of second through holes 62. The shapes, diameters, etc. of the plurality of second through holes 62 may be the same or different.

[0088] The arrangement of the second through holes 62 is not particularly limited, but for example, it is preferable that the center-to-center distance (pitch) of the two closest second through holes 62 be equal to or greater than 90% and equal to or less than 110% of the average value, and more preferably, all of the center-to-center distances (pitch) are equal. When the center-to-center distances (pitch) of the two closest second through holes 62 are all equal, it can be said that the center-to-center distance (pitch) of the two closest second through holes 62 is constant. It is preferable that the center-to-center distance (pitch) of the two closest second through holes 62 be constant in a predetermined region of the wick 30, and more preferably be constant throughout the entire wick 30.

[0089] When the center-to-center distance between the two closest second through holes 62 is constant, the vapor of the working medium 20 can be distributed uniformly on the surface viewed from the thickness direction Z. Therefore, the characteristics of the vapor chamber 1 can be made uniform.

[0090] The center-to-center distance between the two closest second through holes 62 is not particularly limited, but is, for example, not less than 30 μm and not more than 150 μm.

[0091] The wick 30 includes a plurality of first through holes 61 and a plurality of second through holes 62. The arrangement of the plurality of first through holes 61 and the arrangement of the plurality of second through holes 62 are not particularly limited, but it is preferable that the center-to-center distance between the two closest second through holes is smaller (shorter) than the center-to-center distance between the two closest first through holes, and that the center-to-center distance between the closest first through holes 61 and second through holes 62 is constant.

[0092] If the center-to-center distance between the two closest second through holes 62 is smaller (shorter) than the center-to-center distance between the two closest first through holes 61, the second through holes 62 will be arranged at a shorter interval than the first through holes 61, and the number of second through holes 62 per unit area can be made greater than the number of first through holes 61 per unit area.

[0093] The center-to-center distance between the closest first through-hole 61 and second through-hole 62 is not particularly limited, but is, for example, 20 μm or more and 100 μm or less.

[0094] The height of the first protrusion 71 (t １ The length indicated by is, for example, 10 μm or more and 100 μm or less.

[0095] The height of the second protrusion 72 (t ２ The length indicated by is, for example, 10 μm or more and 100 μm or less.

[0096] Height t of the first convex portion 71 １ is the height t of the second protrusion 72 ２ may be equivalent to

[0097] In addition, the height t of the first convex portion 71 １ and the height t of the second protrusion 72 ２The height of at least one of the thicknesses of the main body of the wick 30 (t ０ In particular, the height t １ is the thickness t of the main body of the wick 30 ０ and the height t of the second protrusion 72 is greater than ２ is the thickness t of the main body of the wick 30 ０ It is preferable that it is greater than .

[0098] Height t of the first convex portion 71 １ is the thickness t of the main body of the wick 30 ０ On the other hand, if the height t of the second protrusion 72 is larger than t ２ is the thickness t of the main body of the wick 30 ０ If the second protrusion 72 is larger than 1 / 2, the second protrusion 72 will be sufficiently high, making it easier to form a steam flow path.

[0099] The thickness t of the main body of the wick 30 ０ means the thickness of the main body of the wick 30 (the part that is not deformed by the through holes). If the thickness of the main body is not constant within the sheet, the thickness of the maximum part is taken as the thickness t of the main body of the wick 30. ０ The thickness t of the main body of the wick 30 is defined as ０ is not particularly limited, but is, for example, 5 μm or more and 100 μm or less.

[0100] The shape, height, etc. of the first protrusions 71 provided on the peripheries of the plurality of first through holes 61 may be the same or different.

[0101] The shape, height, etc. of the second protrusions 72 provided on the peripheries of the plurality of second through holes 62 may be the same or different.

[0102] In addition to the first through hole 61 having a first convex portion 71 provided on the periphery and the second through hole 62 having a second convex portion 72 provided on the periphery, the wick 30 may further include a third through hole in which the first convex portion 71 and the second convex portion 72 are not provided.

[0103] When the support pillars 40 are disposed in the internal space of the housing 10, the height of the support pillars 40 is, for example, not less than 50 μm and not more than 1000 μm.

[0104] 2 or 7, the width of the support 40 is not particularly limited as long as it provides a strength sufficient to suppress deformation of the housing 10, but the equivalent circle diameter of the cross section perpendicular to the height direction of the end of the support 40 on the wick 30 side is, for example, 100 μm or more and 2000 μm or less, and preferably 300 μm or more and 1000 μm or less. By increasing the equivalent circle diameter of the support 40, deformation of the housing 10 can be further suppressed. On the other hand, by decreasing the equivalent circle diameter of the support 40, a wider space (vapor flow path) can be secured for the movement of vapor of the working medium 20.

[0105] When multiple support columns 40 are arranged in the internal space of the housing 10, the shapes, heights, etc. of the support columns 40 may be the same or different.

[0106] The arrangement of the support posts 40 is not particularly limited, but is preferably arranged evenly in a predetermined region, and more preferably evenly throughout, for example, so that the center-to-center distance (pitch) between adjacent support posts 40 is constant. By arranging the support posts 40 evenly, it is possible to ensure uniform strength throughout the heat diffusion device, such as a vapor chamber. The center-to-center distance between the support posts 40 is, for example, 100 μm or more and 10,000 μm or less.

[0107] 4, the wick may be one in which half of the first through holes 61 are changed to second through holes 62 in a staggered arrangement in which the first through holes 61 and the second through holes 62 are alternately arranged, as shown in FIG. 4. An example of such a wick will be described with reference to FIG. 10.

[0108] 10 is a plan view schematically illustrating another example of a wick constituting the heat diffusion device according to the first embodiment of the present invention. In the wick 31 shown in FIG. 10, the first through holes 61 and the second through holes 62 are arranged in a staggered pattern. However, the first through holes 61 and the second through holes 62 are not alternately arranged. In a certain region, half of the first through holes 61 are replaced with second through holes 62, instead of the staggered arrangement in which the first through holes 61 and the second through holes 62 are alternately arranged.

[0109] That is, in the region indicated by A1 of the wick 31 shown in Fig. 10, the staggered arrangement in which the first through holes 61 and the second through holes 62 are alternately arranged has been changed to half of the first through holes 61 being replaced by second through holes 62, as in Fig. 4. On the other hand, in the region indicated by A2, the staggered arrangement in which the first through holes 61 and the second through holes 62 are alternately arranged is simpler.

[0110] In the region indicated by A2, the ratio of the number of first through holes 61 to the number of second through holes 62 per unit area is 1:1, but in the region indicated by A1, the ratio of the number of first through holes 61 to the number of second through holes 62 per unit area is 1:3, similar to the wick 30 shown in Fig. 4. Therefore, in the wick 31 as a whole, the number of second through holes 62 per unit area is greater than the number of first through holes 61 per unit area.

[0111] When it is clearly apparent that there are regions where the number of first through holes per unit area and the number of second through holes per unit area are different, as in the case of the wick 31 shown in Figure 10, when looking at the region where the number of second through holes per unit area is greater than the number of first through holes per unit area (the region indicated by A1 in the wick 31 shown in Figure 10), it is preferable that the center-to-center distance (pitch) between the two closest first through holes is such that its minimum and maximum values ​​are 90% or more and 110% or less of the average value, respectively, and it is more preferable that they are all arranged so that they are equal, and it is preferable that the center-to-center distance (pitch) between the two closest second through holes is such that its minimum and maximum values ​​are 90% or more and 110% or less of the average value, respectively, and it is more preferable that they are all arranged so that they are equal.

[0112] [Second Embodiment] Fig. 11 is a cross-sectional view schematically illustrating an example of a heat diffusion device according to a second embodiment of the present invention. In the heat diffusion device 2 shown in Fig. 11, the housing 10 constituting the vapor chamber 1 shown in Figs. 1 and 2 further includes a support 41 in the internal space. As shown in Fig. 11, the internal space of the housing 10 may include the support 41 in contact with the first inner surface 11a. By arranging the support 41 in the internal space of the housing 10, a space serving as a liquid flow path can be formed between the first inner surface 11a and the wick 30, thereby improving heat transport efficiency.

[0113] When the support pillars 41 are disposed in the internal space of the housing 10, the height of the support pillars 41 is, for example, not less than 25 μm and not more than 500 μm.

[0114] 11 , the width of the support 41 is not particularly limited as long as it provides the strength to suppress deformation of the housing 10, but the equivalent circle diameter of the cross section perpendicular to the height direction of the end of the support 41 on the wick 30 side is, for example, 100 μm or more and 2000 μm or less, and preferably 300 μm or more and 1000 μm or less. Increasing the equivalent circle diameter of the support 41 can further suppress deformation of the housing 10. On the other hand, decreasing the equivalent circle diameter of the support 41 can ensure a wider space (liquid flow path) for the movement of the liquid of the working medium 20.

[0115] When multiple support columns 41 are arranged in the internal space of the housing 10, the shape, height, etc. of the support columns 41 may be the same or different.

[0116] The arrangement of the support columns 41 is not particularly limited, but they are preferably arranged evenly in a predetermined region, and more preferably evenly throughout, for example, so that the center-to-center distance (pitch) between adjacent support columns 41 is constant. By arranging the support columns 41 evenly, it is possible to ensure uniform strength throughout the heat diffusion device, such as a vapor chamber. The center-to-center distance between the support columns 41 is, for example, 100 μm or more and 10,000 μm or less.

[0117] [Third embodiment] Fig. 12 is a perspective view schematically showing an example of a heat diffusion device according to a third embodiment of the present invention. Fig. 13 is a cross-sectional view schematically showing an example of a heat diffusion device according to the third embodiment of the present invention. Fig. 13 is an example of a cross-sectional view taken along line XIII-XIII of the heat diffusion device shown in Fig. 12.

[0118] As in the heat spreading device 3 shown in FIGS. 12 and 13, no support pillars may be arranged in the internal space of the housing 10.

[0119] The heat diffusion device 3 may be planar or tubular as a whole. That is, the housing 10 may be planar or tubular as a whole. Here, "tubular" means a shape in which either the width or the length is 10 times or more the thickness. When the heat diffusion device 3 is tubular as a whole, the shape of the tube is not particularly limited, and examples thereof include a rectangular tube, a cylindrical tube, and an elliptical tube.

[0120] [Other Embodiments] The heat diffusion device of the present invention is not limited to the above-described embodiments, and various applications and modifications can be made within the scope of the present invention with respect to the configuration, manufacturing conditions, etc. of the heat diffusion device.

[0121] In the heat diffusion device of the present invention, the housing may have one or more evaporation sections, i.e., one or more heat sources may be arranged on the outer wall surface of the housing.

[0122] In the heat diffusion device of the present invention, when the housing is composed of a first sheet and a second sheet, the first sheet and the second sheet may overlap so that their edges coincide, or they may overlap so that their edges are offset.

[0123] In the heat spreading device of the present invention, when the housing is composed of a first sheet and a second sheet, the material constituting the first sheet may be different from the material constituting the second sheet. For example, by using a high-strength material for the first sheet, stress acting on the housing can be dispersed. Furthermore, by using different materials for the two sheets, one sheet can achieve one function and the other sheet can achieve another function. The above functions are not particularly limited, but include, for example, a heat conduction function and an electromagnetic wave shielding function.

[0124] The heat diffusion device of the present invention can be installed in an electronic device for the purpose of heat dissipation. Therefore, an electronic device equipped with the heat diffusion device of the present invention also constitutes the present invention. Examples of electronic devices of the present invention include smartphones, tablet computers, laptops, game consoles, and wearable devices. As described above, the heat diffusion device of the present invention operates autonomously without requiring external power and can rapidly diffuse heat in two dimensions by utilizing the latent heat of evaporation and latent heat of condensation of the working medium. Therefore, an electronic device equipped with the heat diffusion device of the present invention can effectively dissipate heat within a limited space inside the electronic device.

[0125] The present specification discloses the following:

[0126] The present disclosure (1) is a heat diffusion device comprising: a housing having a first inner surface and a second inner surface opposing each other in a thickness direction and having an internal space; a working medium sealed in the internal space of the housing; and a sheet-like wick arranged in the internal space of the housing, wherein the wick includes a plurality of first through holes penetrating in the thickness direction and a plurality of second through holes penetrating in the thickness direction, wherein a first convex portion protruding in a direction approaching the first inner surface is provided on the periphery of the first through hole; and a second convex portion protruding in a direction approaching the second inner surface is provided on the periphery of the second through hole; in the thickness direction, the distance between the wick and the second inner surface is smaller than the distance between the wick and the first inner surface; and the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

[0127] The present disclosure (2) is the heat spreading device according to the present disclosure (1), wherein the distance between the outer walls of the first protrusions decreases toward the tip of the first protrusions.

[0128] The present disclosure (3) is the heat spreading device according to the present disclosure (1) or (2), wherein the distance between the outer walls of the second protrusions decreases toward the tip of the second protrusions.

[0129] The present disclosure (4) is a heat spreading device in any combination with any of the present disclosures (1) to (3), in which the center-to-center distance between the two closest first through holes is constant.

[0130] The present disclosure (5) is a heat spreading device in any combination with any of the present disclosures (1) to (4), in which the center-to-center distance between the two closest second through holes is constant.

[0131] The present disclosure (6) is a heat diffusion device in any combination with any of the present disclosures (1) to (3), in which the center-to-center distance between the two closest first through holes is constant, the center-to-center distance between the two closest second through holes is constant, and the center-to-center distance between the two closest second through holes is smaller than the center-to-center distance between the two closest first through holes.

[0132] The present disclosure (7) is a heat diffusion device in any combination with any of the present disclosures (1) to (6), in which the center-to-center distance between the nearest first through holes and the nearest second through holes is constant.

[0133] The present disclosure (8) is a heat diffusion device in any combination with any of the present disclosures (1) to (7), in which the height of the first convex portion is equal to the height of the second convex portion.

[0134] The present disclosure (9) is a heat diffusion device in any combination with any of the present disclosures (1) to (8), in which at least one of the height of the first convex portion and the height of the second convex portion is greater than the thickness of the main body portion of the wick.

[0135] The present disclosure (10) is a heat diffusion device in any combination with any of the present disclosures (1) to (9), in which the height of the first convex portion is greater than the thickness of the main body of the wick, and the height of the second convex portion is greater than the thickness of the main body of the wick.

[0136] The present disclosure (11) is a heat diffusion device in any combination with any of the present disclosures (1) to (10), wherein the wick is made of a porous body.

[0137] The present disclosure (12) is a heat diffusion device in any combination with any of the present disclosures (1) to (11), wherein a support is arranged in the internal space of the housing so as to contact the first inner surface.

[0138] The present disclosure (13) is an electronic device comprising a heat spreading device in any combination with any of the present disclosures (1) to (12).

[0139] The present disclosure (14) is a sheet-like wick having, at least in a portion thereof, a plurality of first through holes penetrating in a thickness direction and a plurality of second through holes penetrating in the thickness direction, wherein a first convex portion protruding in one direction in the thickness direction is provided on the periphery of the first through holes, and a second convex portion protruding in the opposite direction to the thickness direction is provided on the periphery of the second through holes, and wherein the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

[0140] REFERENCE SIGNS LIST 1 Vapor chamber (heat diffusion device) 2, 3 Heat diffusion device 10 Housing 11 First sheet 11a First inner surface 12 Second sheet 12a Second inner surface 20 Working medium 30, 31 Wick 40, 41 Support 61 First through-hole 62 Second through-hole 71 First protrusion 72 Second protrusion t ０ Thickness of the main body of the wick t １ Height of the first protrusion t ２ Height of second protrusion HS Heat source P Space between wick and support X Width direction Y Length direction Z Thickness direction α, β １ , β ２ Row of through holes

Claims

1. A heat diffusion device comprising: a housing having a first inner surface and a second inner surface opposed in a thickness direction and having an internal space; a working medium sealed in the internal space of the housing; and a sheet-like wick arranged in the internal space of the housing, wherein the wick has, in at least a portion thereof, a plurality of first through holes penetrating in the thickness direction and a plurality of second through holes penetrating in the thickness direction, the periphery of the first through holes is provided with a first convex portion that protrudes in a direction approaching the first inner surface, and the periphery of the second through holes is provided with a second convex portion that protrudes in a direction approaching the second inner surface, the distance between the wick and the first inner surface in the thickness direction is smaller than the distance between the wick and the second inner surface, and the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

2. The heat spreading device according to claim 1, wherein the distance between the outer walls of said first protrusions decreases toward the tip of said first protrusions.

3. A heat spreading device according to claim 1 or 2, wherein the distance between the outer walls of said second protrusions decreases toward the tip of said second protrusions.

4. A heat spreading device according to any one of claims 1 to 3, wherein the center-to-center distance between two of the first through holes that are closest to each other is constant.

5. A heat spreading device according to any one of claims 1 to 4, wherein the center-to-center distance between two of the second through holes that are closest to each other is constant.

6. A heat spreading device according to any one of claims 1 to 3, wherein the center-to-center distance between the two nearest first through holes is constant, the center-to-center distance between the two nearest second through holes is constant, and the center-to-center distance between the two nearest second through holes is smaller than the center-to-center distance between the two nearest first through holes.

7. A heat spreading device according to any one of claims 1 to 6, wherein the center-to-center distance between the nearest first through holes and the nearest second through holes is constant.

8. A heat spreading device according to any one of claims 1 to 7, wherein the height of said first protrusion is equal to the height of said second protrusion.

9. A heat spreading device according to any one of claims 1 to 8, wherein the height of at least one of the first protrusion and the second protrusion is greater than the thickness of the main body of the wick.

10. A heat spreading device according to any one of claims 1 to 9, wherein the height of the first protrusion is greater than the thickness of the main body of the wick, and the height of the second protrusion is greater than the thickness of the main body of the wick.

11. A heat diffusion device according to any one of claims 1 to 10, wherein the wick is made of a porous material.

12. A heat spreading device according to any one of claims 1 to 11, wherein a support is disposed in the internal space of the housing so as to contact the first inner surface.

13. An electronic device comprising the heat spreading device according to any one of claims 1 to 12.

14. A wick for a heat diffusion device, comprising a sheet-like wick having, at least in a portion thereof, a plurality of first through holes penetrating in the thickness direction and a plurality of second through holes penetrating in the thickness direction, wherein the periphery of each of the first through holes is provided with a first convex portion protruding in one direction in the thickness direction, and the periphery of each of the second through holes is provided with a second convex portion protruding in the opposite direction to the thickness direction, and wherein the number of the second through holes per unit area of ​​the wick when viewed in the thickness direction is greater than the number of the first through holes per unit area.

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