Heat Diffusion Device

Abstract

A vapor chamber (1) that is one embodiment of this thermal diffusion device comprises: a housing (10) that has a first inner wall surface (11a) and a second inner wall surface (12a) facing one other in the thickness direction (Z); a working medium (20) that is enclosed in an internal space of the housing (10); and a wick structure (30) that is disposed in said internal space of the housing (10). The wick structure (30) includes: a support portion (31) that is in contact with the first inner wall surface (11a); and a perforated portion (32) that is composed of the same material as the support portion (31) and is integrally formed with the support portion (31).

Description

[Technical field]

[0001] The present invention relates to a heat spreading device. [Background technology]

[0002] In recent years, the amount of heat generated has increased due to the high integration and high performance of elements. In addition, as products become smaller, the heat density increases, making heat dissipation measures important. This situation is particularly noticeable in the field of mobile terminals such as smartphones and tablets. Graphite sheets are often used as heat countermeasures, but since their heat transport capacity is insufficient, the use of various heat countermeasures is being considered. In particular, 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 working fluid) 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 that absorbs heat from the heat generating element and evaporates in the vapor chamber, then moves inside the vapor chamber, is cooled, and returns to a liquid phase. The working medium that has returned to the liquid phase moves again to the evaporation section on the heat generating element side by the capillary force of the wick, and cools the heat generating element. By repeating this process, the vapor chamber operates autonomously without an external power source, and can diffuse heat two-dimensionally at high speed by utilizing the latent heat of evaporation and latent heat of condensation of the working medium.

[0004] Patent Document 1 discloses a thermal ground plane, which is an example of a vapor chamber. The thermal ground plane described in Patent Document 1 includes a first planar substrate member, a plurality of micropillars arranged on the first planar substrate member, a mesh bonded to at least some of the micropillars, a vapor core arranged on at least one of the first planar substrate member, the micropillars, and the mesh, and a second planar substrate member arranged on the first planar substrate member, the mesh separating the micropillars from the vapor core, and the first planar substrate member and the second planar substrate member surrounding the micropillars, the mesh, and the vapor core. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Pat. No. 10,527,358 Summary of the Invention [Problem to be solved by the invention]

[0006] In the vapor chamber described in Patent Document 1, the wick is composed of supports such as micropillars and a porous body such as a mesh. The supports such as micropillars have a shape such as a square pillar or a cylindrical shape, and a liquid flow path for the working medium is formed between the supports. Therefore, the wider the distance between the supports, the wider the width of the liquid flow path, and the higher the transmittance. On the other hand, if the width of the liquid flow path is too wide, the porous body such as a mesh is likely to fall between the supports, which may cause the position of the porous body to shift and reduce the stability of the wick. For the above reasons, it is difficult to greatly widen the width of the liquid flow path, so it can be said that there is room for improvement in terms of improving the characteristics of the vapor chamber.

[0007] The above problem is not limited to vapor chambers, but is a problem common to heat diffusion devices that are capable of diffusing heat using a similar structure to a vapor chamber.

[0008] The present invention has been made to solve the above problems, and aims to provide a heat diffusion device having a wick structure that is structurally stable even when the width of the liquid flow path of the working medium is widened. Another aim of the present invention is to provide an electronic device having the heat diffusion device. [Means for solving the problem]

[0009] The heat diffusion device of the present invention includes a housing having a first inner wall surface and a second inner wall surface opposed to each other in a thickness direction, a working medium sealed in an internal space of the housing, and a wick structure disposed in the internal space of the housing. The wick structure includes a support portion in contact with the first inner wall surface, and a perforated portion made of the same material as the support portion and integrally formed with the support portion.

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

[0011] According to the present invention, it is possible to provide a heat diffusion device having a wick structure that is structurally stable even when the width of the liquid flow path of the working medium is widened. Furthermore, according to the present invention, it is possible to provide an electronic device having the heat diffusion device. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing a typical example of a heat spreading device of the present invention. [Diagram 2] FIG. 2 is an example of a cross-sectional view of the heat spreading device taken along line II-II of FIG. [Diagram 3] FIG. 3 is a partially enlarged cross-sectional view that typically illustrates an example of a wick structure that constitutes the heat diffusion device shown in FIG. [Figure 4]Fig. 4A is an example of a plan view of the wick structure shown in Fig. 3 as seen from the support side. Fig. 4B is another example of a plan view of the wick structure shown in Fig. 3 as seen from the support side. [Diagram 5] FIG. 5 is a partially enlarged cross-sectional view that typically illustrates a first modified example of the wick structure. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view that typically illustrates a second modified example of the wick structure. [Figure 7] FIG. 7 is a partially enlarged cross-sectional view that typically illustrates a third modified example of the wick structure. [Figure 8] FIG. 8 is a plan view diagrammatically illustrating a fourth modified example of the wick structure. [Figure 9] FIG. 9 is a cross-sectional view that typically shows a first modified example of the wick structure shown in FIG. [Figure 10] FIG. 10 is a cross-sectional view that typically shows a second modified example of the wick structure shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view that typically shows a third modified example of the wick structure shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view that typically shows a fourth modified example of the wick structure shown in FIG. [Figure 13] FIG. 13 is a cross-sectional view that typically shows a fifth modified example of the wick structure shown in FIG. [Figure 14] FIG. 14 is a cross-sectional view that typically shows a sixth modified example of the wick structure shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The heat spreading device of the present invention will now be described. However, the present invention is not limited to the following embodiments, and can be modified and applied as appropriate within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual preferred configurations of the present invention described below.

[0014] The heat diffusion device of the present invention is characterized in that the support and perforated portions constituting the wick structure are made of the same material and are integrally constructed. This prevents uneven adhesion between the support and perforated portions. As a result, even if the spacing between the support portions that form the liquid flow paths of the working medium is widened, the wick structure is structurally stable, and deterioration of the characteristics of the heat diffusion device can be suppressed. Furthermore, since the support and perforated portions are integrated, the strength of the wick structure is also improved.

[0015] In this specification, "integrally constructed" means that there is no interface between the support part and the perforated part, specifically, that the boundary between the support part and the perforated part cannot be distinguished. For example, in a wick structure in which a copper pillar as the support part and a copper mesh as the perforated part are fixed by diffusion bonding or spot welding, it is difficult to bond the support part and the perforated part over the entire surface, so a gap occurs in part between the support part and the perforated part. In such a wick structure, since the boundary between the support part and the perforated part can be distinguished, it can be said that the support part and the perforated part are not integrally constructed.

[0016] In the following, a vapor chamber will be described as an example of an embodiment of the heat spreading device of the present invention, but the heat spreading device of the present invention can also be applied to heat spreading devices such as heat pipes.

[0017] The drawings shown below are schematic, and the dimensions and aspect ratios may differ from the actual products.

[0018] In this specification, terms indicating the relationship between elements (e.g., "vertical," "parallel," "orthogonal," etc.) and terms indicating the shapes of elements are not intended to be used in a strict sense, but are intended to include a range of substantial equivalence, for example, a difference of a few percent.

[0019] Fig. 1 is a perspective view showing a typical example of a heat spreading device of the present invention, Fig. 2 is an example of a cross-sectional view taken along line II-II of the heat spreading device shown in Fig. 1.

[0020] 1 includes a hollow housing 10 that is airtightly sealed. The housing 10 has a first inner wall surface 11a and a second inner wall surface 12a that face each other in a thickness direction Z. The vapor chamber 1 further includes a working medium 20 sealed in the internal space of the housing 10, and a wick structure 30 disposed in the internal space of the housing 10.

[0021] An evaporation section that evaporates the enclosed working medium 20 is provided in the housing 10. As shown in Fig. 1, a heat source HS, which is a heat generating element, is disposed on the outer wall 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). A portion of the internal space of the housing 10 that is adjacent to the heat source HS and that is heated by the heat source HS corresponds to the evaporation section.

[0022] 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 means 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, of the thickness.

[0023] 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 appropriately set 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.

[0024] Housing 10 is preferably constructed from opposing first and second sheets 11 and 12 whose outer edges are joined together.

[0025] When the housing 10 is composed of the first sheet 11 and the second sheet 12, the material constituting the first sheet 11 and the second sheet 12 is not particularly limited as long as it has properties suitable for use as a vapor chamber, such as thermal conductivity, strength, flexibility, and the like. The material constituting 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, and is particularly preferably copper. The materials constituting the first sheet 11 and the second sheet 12 may be the same or different, but are preferably the same.

[0026] 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 method of such joining is not particularly limited, but for example, laser welding, resistance welding, diffusion bonding, brazing, TIG welding (tungsten-inert gas welding), ultrasonic bonding, or resin sealing can be used, and preferably laser welding, resistance welding, or brazing can be used.

[0027] 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 further 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 thin in some parts.

[0028] 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.

[0029] The thickness of the entire vapor chamber 1 is not particularly limited, but is preferably 50 μm or more and 500 μm or less.

[0030] 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 shapes that are combinations of these. The planar shape of the housing 10 may be an L-shape, a C-shape, a stepped shape, or the like. The housing 10 may have a through hole. The planar shape of the housing 10 may be a shape that corresponds to the use of the vapor chamber, the shape of the location where the vapor chamber is incorporated, and other parts that exist in the vicinity.

[0031] 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 for example, water, alcohols, alternative fluorocarbons, etc. can be used. For example, the working medium 20 is an aqueous compound, and is preferably water.

[0032] The wick structure 30 has a capillary structure that can move the working medium 20 by capillary force. The capillary structure of the wick structure 30 may be a known structure used in conventional vapor chambers.

[0033] The size and shape of the wick structure 30 are not particularly limited, but for example, it is preferable that the wick structure 30 is arranged continuously in the internal space of the housing 10. The wick structure 30 may be arranged in the entire internal space of the housing 10, or the wick structure 30 may not be arranged in a part of the internal space of the housing 10.

[0034] FIG. 3 is a partially enlarged cross-sectional view that typically illustrates an example of a wick structure that constitutes the heat diffusion device shown in FIG.

[0035] As shown in FIGS. 2 and 3, the wick structure 30 includes a support portion 31 in contact with the first inner wall surface 11a, and a perforated portion 32 made of the same material as the support portion 31 and integrally formed with the support portion 31.

[0036] The material constituting the support portion 31 and the perforated portion 32 is not particularly limited, but examples thereof include resin, metal, ceramics, or mixtures or laminates thereof.

[0037] Fig. 4A is an example of a plan view of the wick structure shown in Fig. 3 as seen from the support side. Fig. 4B is another example of a plan view of the wick structure shown in Fig. 3 as seen from the support side.

[0038] In the wick structure 30, the support 31 includes a plurality of columnar members. By holding the liquid phase working medium 20 between the columnar members, the heat transport capacity of the vapor chamber 1 can be improved. Here, "columnar" means a shape in which the ratio of the length of the long side of the base to the length of the short side of the base is less than 5 times.

[0039] The shape of the columnar member is not particularly limited, and examples thereof include a cylindrical shape, a prismatic shape, a truncated cone shape, a truncated pyramid shape, etc. In the example shown in Fig. 4A, the cross-sectional shape perpendicular to the height direction of the support part 31 is a square shape, and in the example shown in Fig. 4B, the cross-sectional shape perpendicular to the height direction of the support part 31 is a circle.

[0040] The columnar member only needs to be taller than its surroundings. Therefore, the columnar member includes not only a portion protruding from first inner wall surface 11a, but also a portion that is relatively taller due to a recess formed in first inner wall surface 11a.

[0041] For example, a metal porous film, a sintered body, a porous body, etc. formed by etching or metal processing are used as the perforated portion 32. The sintered body that is the material of the perforated portion 32 may be composed of a porous sintered body such as a porous sintered metal body or a porous sintered ceramic body, and is preferably composed of a porous sintered body of copper or nickel. The porous body that is the material of the perforated portion 32 may be composed of a porous metal body, a porous ceramic body, a porous resin body, etc.

[0042] The wick structure 30 in which the support portion 31 and the perforated portion 32 are integrally formed can be produced by, for example, an etching technique, a printing technique using multiple layers of coating, or other multi-layer techniques.

[0043] The support portion 31 may be integral with the housing 10, or may be formed, for example, by etching the first inner wall surface 11a of the housing 10.

[0044] 2 and 3, the support portion 31 preferably has a tapered shape that narrows from the perforated portion 32 toward the first inner wall surface 11a. This makes it possible to widen the flow path between the support portions 31 on the housing 10 side while suppressing the perforated portion 32 from falling between the support portions 31. As a result, the transmittance increases and the maximum heat transport amount increases.

[0045] 2, 3, 4A, and 4B, when the perforated portion 32 is viewed from the thickness direction Z, it is preferable that no holes 32a of the perforated portion 32 exist in the region overlapping with the support portion 31. In this case, the working medium 20 is less likely to be trapped on the support portion 31.

[0046] The arrangement of the support parts 31 is not particularly limited, but is preferably arranged evenly in a predetermined region, and more preferably evenly over the entire area, for example, so that the center-to-center distance (pitch) of the support parts 31 is constant.

[0047] The center distance of the support parts 31 (P in FIG. 4A or FIG. 4B) 31 The width of the support portion 31 (in FIG. 4A or FIG. 4B, W 31 The length indicated by T in FIG. 3 is, for example, 20 μm or more and 500 μm or less. 31 The length indicated by is, for example, 10 μm or more and 100 μm or less.

[0048] The arrangement of the holes 32a in the perforated portion 32 is not particularly limited, but is preferably arranged evenly in a specified area, and more preferably evenly throughout, for example so that the center-to-center distance (pitch) of the holes 32a in the perforated portion 32 is constant.

[0049] The center distance between the holes 32a of the perforated portion 32 (P in FIG. 4A or FIG. 4B) 32The diameter of the hole 32a of the perforated portion 32 (in FIG. 4A or FIG. 4B, φ 32 The thickness of the perforated portion 32 (in FIG. 3, T 32 The length indicated by is, for example, 5 μm or more and 50 μm or less.

[0050] FIG. 5 is a partially enlarged cross-sectional view that typically illustrates a first modified example of the wick structure.

[0051] As in the wick structure 30A shown in FIG. 5, when the perforated portion 32 is viewed from the thickness direction Z, holes 32a of the perforated portion 32 may be present in the region overlapping with the support portion 31.

[0052] FIG. 6 is a partially enlarged cross-sectional view that typically illustrates a second modified example of the wick structure.

[0053] 6, the support part 31 and the perforated part 32 are made of a porous body. By making not only the perforated part 32 but also the support part 31 of a porous body, the capillary force of the wick structure 30B can be improved.

[0054] Examples of the porous body constituting the support portion 31 and the perforated portion 32 include porous sintered bodies such as porous sintered metal bodies and porous sintered ceramic bodies, or porous bodies such as porous metal bodies, porous ceramic bodies, and porous resin bodies.

[0055] The wick structure 30B made of a porous body can be produced by, for example, a printing technique using a multi-layer coating of a metal paste or a ceramic paste. In this case, the content of the metal or ceramic in the paste for forming the support portion 31 may be the same as the content of the metal or ceramic in the paste for forming the perforated portion 32, may be less than the content of the metal or ceramic in the paste for forming the perforated portion 32, or may be more than the content of the metal or ceramic in the paste for forming the perforated portion 32. For example, by making the content of the metal or ceramic in the paste for forming the support portion 31 greater than the content of the metal or ceramic in the paste for forming the perforated portion 32, the density of the support portion 31 can be made greater than the density of the perforated portion 32. As a result, the strength of the support portion 31 can be increased.

[0056] FIG. 7 is a partially enlarged cross-sectional view that typically illustrates a third modified example of the wick structure.

[0057] In the wick structure 30C shown in Fig. 7, for example, a part of the metal foil is bent and recessed by pressing or the like, to form the support part 31 in the recessed part. A vapor space is formed in the recessed part of the support part 31, improving the thermal conductivity. Not limited to the example shown in Fig. 7, when pressing the metal foil, a through hole may be formed in the recessed part when the part of the metal foil is bent, depending on the condition of the pressing.

[0058] In the wick structure 30C, the holes 32a of the perforated portion 32 can be formed, for example, by punching the metal foil constituting the wick structure 30 by press working. In this case, the press working for forming the support portion 31 and the press working for forming the holes 32a of the perforated portion 32 may be performed simultaneously.

[0059] It is preferable that the thickness of the metal foil is constant before pressing or the like. However, the metal foil may become thinner in the bent portion. From the above, in the wick structure 30C, it is preferable that the thickness of the support portion 31 is the same as or smaller than the thickness of the perforated portion 32.

[0060] Fig. 8 is a plan view diagrammatically illustrating a fourth modified example of the wick structure, as viewed from the support portion side.

[0061] In the wick structure 30D shown in Fig. 8, the support portion 31 includes a plurality of rail-shaped members. By holding the liquid phase working medium 20 between the rail-shaped members, the heat transport capacity of the vapor chamber 1 can be improved. Here, "rail-shaped" means a shape in which the ratio of the length of the long side of the bottom surface to the length of the short side of the bottom surface is 5 times or more.

[0062] The cross-sectional shape perpendicular to the extension direction of the rail-shaped member is not particularly limited, but examples thereof include a polygon such as a rectangle, a semicircle, a semi-ellipse, and a combination of these.

[0063] The rail-shaped member only needs to be relatively taller than its surroundings. Therefore, the rail-shaped member includes not only a portion protruding from the first inner wall surface 11a, but also a portion whose height is relatively higher due to a groove formed in the first inner wall surface 11a.

[0064] 2, a support 40 in contact with the second inner wall 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 structure 30.

[0065] The material constituting the support 40 is not particularly limited, but examples thereof include resin, metal, ceramics, or a mixture or laminate thereof. The support 40 may be integral with the housing 10, or may be formed, for example, by etching the second inner wall surface 12a of the housing 10.

[0066] The shape of the support 40 is not particularly limited as long as it can support the housing 10 and the wick structure 30, but the cross-sectional shape perpendicular to the height direction of the support 40 may be, for example, a polygon such as a rectangle, a circle, an ellipse, etc.

[0067] The height of the support pillars 40 may be the same or different in one vapor chamber.

[0068] 2, the width of the support 40 is not particularly limited as long as it provides a strength capable of suppressing deformation of the casing 10, but the circle-equivalent diameter of the cross section perpendicular to the height direction of the end of the support 40 is, for example, 100 μm to 2000 μm, and preferably 300 μm to 1000 μm. By increasing the circle-equivalent diameter of the support 40, deformation of the casing 10 can be further suppressed. On the other hand, by decreasing the circle-equivalent diameter of the support 40, a larger space can be secured for the movement of the vapor of the working medium 20.

[0069] The arrangement of the pillars 40 is not particularly limited, but is preferably arranged evenly in a predetermined region, more preferably evenly throughout, for example, so that the distance between the pillars 40 is constant. By arranging the pillars 40 evenly, it is possible to ensure uniform strength throughout the vapor chamber 1.

[0070] The heat spreading device of the present invention is not limited to the above-described embodiment, 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 spreading device.

[0071] For example, a protrusion may be provided on the periphery of the hole of the perforated portion, which protrudes toward the first inner wall surface or the second inner wall surface of the housing in the thickness direction. In this case, the protrusion may be provided only on a part of the periphery of the hole of the perforated portion, but is preferably provided on the entire periphery of the hole of the perforated portion.

[0072] When a convex portion is provided on the periphery of a hole in the perforated portion, there may be a mixture of holes whose periphery has a convex portion approaching the first inner wall surface and holes whose periphery has a convex portion approaching the second inner wall surface, or there may be a mixture of holes whose periphery has a convex portion and holes whose periphery does not have a convex portion.

[0073] When the protrusion approaching the first inner wall surface is provided on the periphery of the hole of the perforated portion, the protrusion may have a lid portion at an end portion on the first inner wall surface side that narrows the opening of the protrusion. Similarly, when the protrusion approaching the second inner wall surface is provided on the periphery of the hole of the perforated portion, the protrusion may have a lid portion at an end portion on the second inner wall surface side that narrows the opening of the protrusion.

[0074] The convex portion can be formed, for example, by punching the metal constituting the perforated portion by press working. In this case, the convex portion may be formed simultaneously with the holes in the perforated portion, or may be formed separately from the holes in the perforated portion. In the punching by press working, the shape of the convex portion can be adjusted by appropriately adjusting the punching depth, etc. In addition, the punching depth means, for example, how far the punch is pressed in the punching direction when punching with a punch.

[0075] The thickness of the protruding portion may be the same as or different from the thickness of the perforated portion other than the protruding portion. Also, the thickness of the protruding portion may be the same as or different from the thickness of the supporting portion.

[0076] In particular, when forming the support portion by pressing metal foil, as in the wick structure 30C shown in Figure 7, it is preferable that the press processing to form the support portion and the press processing to form the holes and protrusions of the perforated portion are performed simultaneously.

[0077] FIG. 9 is a cross-sectional view that typically shows a first modified example of the wick structure shown in FIG.

[0078] In the wick structure 30E shown in Fig. 9, a protrusion 33a is provided on the periphery of the hole 32a of the perforated portion 32, approaching the second inner wall surface 12a (see Fig. 2) of the housing 10 in the thickness direction Z. In the example shown in Fig. 9, the protrusion 33a has a shape in which the distance between the outer walls of the protrusion 33a is constant in a cross section along the thickness direction Z in a direction approaching the second inner wall surface 12a (upward in Fig. 9).

[0079] FIG. 10 is a cross-sectional view that typically shows a second modified example of the wick structure shown in FIG.

[0080] In the wick structure 30F shown in FIG. 10, the periphery of the hole 32a of the perforated portion 32 is provided with a convex portion 33b approaching the second inner wall surface 12a (see FIG. 2) of the housing 10 in the thickness direction Z. In the example shown in FIG. 10, the convex portion 33b has a tapered shape in which the distance between the outer walls of the convex portion 33b narrows toward the second inner wall surface 12a (upward in FIG. 10) in a cross section along the thickness direction Z. The convex portion 33b may have an inverse tapered shape in which the distance between the outer walls of the convex portion 33b widens toward the second inner wall surface 12a (upward in FIG. 10) in a cross section along the thickness direction Z. In these cases, the convex portion 33b may have a convex shape toward the second inner wall surface 12a side (upward in FIG. 10) or toward the first inner wall surface 11a side (downward in FIG. 10) in a cross section along the thickness direction Z.

[0081] FIG. 11 is a cross-sectional view that typically shows a third modified example of the wick structure shown in FIG.

[0082] In the wick structure 30G shown in Fig. 11, a protrusion 33c is provided on the periphery of the hole 32a of the perforated portion 32, approaching the second inner wall surface 12a (see Fig. 2) of the housing 10 in the thickness direction Z. The protrusion 33c has a lid portion 34 that narrows the opening of the protrusion 33c at the end portion on the second inner wall surface 12a side (upper side in Fig. 11).

[0083] FIG. 12 is a cross-sectional view that typically shows a fourth modified example of the wick structure shown in FIG.

[0084] In the wick structure 30H shown in Fig. 12, a protrusion 33d is provided on the periphery of the hole 32a of the perforated portion 32, approaching the first inner wall surface 11a (see Fig. 2) of the housing 10 in the thickness direction Z. In the example shown in Fig. 12, the protrusion 33d has a shape in which the distance between the outer walls of the protrusion 33d is constant in a cross section along the thickness direction Z in a direction approaching the first inner wall surface 11a (downward in Fig. 12).

[0085] FIG. 13 is a cross-sectional view that typically shows a fifth modified example of the wick structure shown in FIG.

[0086] In the wick structure 30I shown in FIG. 13, a convex portion 33e is provided on the periphery of the hole 32a of the perforated portion 32, approaching the first inner wall surface 11a (see FIG. 2) of the housing 10 in the thickness direction Z. In the example shown in FIG. 13, the convex portion 33e has a tapered shape in which the distance between the outer walls of the convex portion 33e narrows toward the first inner wall surface 11a (downward in FIG. 13) in a cross section along the thickness direction Z. The convex portion 33e may have an inverse tapered shape in which the distance between the outer walls of the convex portion 33e widens toward the first inner wall surface 11a (downward in FIG. 13) in a cross section along the thickness direction Z. In these cases, the convex portion 33e may have a convex shape toward the second inner wall surface 12a side (upper side in FIG. 13) or toward the first inner wall surface 11a side (lower side in FIG. 13) in a cross section along the thickness direction Z.

[0087] FIG. 14 is a cross-sectional view that typically shows a sixth modified example of the wick structure shown in FIG.

[0088] In the wick structure 30J shown in Fig. 14, a protrusion 33f is provided on the periphery of the hole 32a of the perforated portion 32, approaching the first inner wall surface 11a (see Fig. 2) of the housing 10 in the thickness direction Z. The protrusion 33f has a lid portion 34 that narrows the opening of the protrusion 33f at the end on the first inner wall surface 11a side (the lower side in Fig. 14).

[0089] In the heat diffusion device of the present invention, the housing may have one evaporation section or multiple evaporation sections. That is, one heat source or multiple heat sources may be arranged on the outer wall surface of the housing. The number of evaporation sections and heat sources is not particularly limited.

[0090] In the heat spreading 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 ends coincide with each other, or they may overlap so that their ends are misaligned.

[0091] In the heat diffusion 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, the stress applied to the housing can be dispersed. In addition, by using different materials for both sheets, one sheet can obtain one function and the other sheet can obtain another function. The above functions are not particularly limited, but examples thereof include a heat conduction function and an electromagnetic wave shielding function.

[0092] The heat diffusion device of the present invention can be mounted on an electronic device for the purpose of heat dissipation. Therefore, an electronic device equipped with the heat diffusion device of the present invention is also one of the present inventions. Examples of the electronic device of the present invention include a smartphone, a tablet terminal, a notebook computer, a game device, a wearable device, and the like. As described above, the heat diffusion device of the present invention operates autonomously without requiring an external power source, and can diffuse heat two-dimensionally at high speed by utilizing the latent heat of evaporation and the latent heat of condensation of the working medium. Therefore, the electronic device equipped with the heat diffusion device of the present invention can effectively realize heat dissipation in a limited space inside the electronic device. [Industrial Applicability]

[0093] The heat spreading device of the present invention can be used for a wide range of applications in the field of mobile information terminals, etc. For example, it can be used to lower the temperature of a heat source such as a CPU and extend the operating time of electronic devices, and can be used in smartphones, tablet terminals, notebook computers, etc. [Explanation of symbols]

[0094] 1 Vapor chamber (thermal diffusion device) 10. Chassis 11 Sheet 1 11a 1st inner wall surface 12 2nd Sheet 12a Second inner wall 20 Working medium 30, 30A, 30B, 30C, 30D, 30E, 30F, 30G, 30H, 30I, 30J Wick structure 31 Support part 32 Perforated part 32a Hole in perforated section 33a, 33b, 33c, 33d, 33e, 33f convex parts 34 Lid 40 pillars HS heat source P 31 Center distance of supports P 32 Center distance of holes in perforated section T 31 Support Height T 32 Perforated part thickness W 31 Support width X Width direction Y Length direction Z thickness direction φ 32 Hole diameter of perforated part

Claims

1. a housing having a first inner wall surface and a second inner wall surface opposed to each other in a thickness direction; A working medium sealed in the internal space of the housing; a wick structure disposed in the internal space of the housing, The wick structure is made of a metal foil including a support portion in contact with the first inner wall surface and a perforated portion having a punched hole, the support portion integrally formed with the perforated portion is formed by a portion of the metal foil recessed toward the first inner wall surface, a protrusion that approaches the first inner wall surface or the second inner wall surface in the thickness direction is provided on a periphery of the punched hole, The convex portion has a tapered shape in which the distance between the outer walls becomes narrower toward the tip, or a reverse tapered shape in which the distance between the outer walls becomes wider toward the tip, a vapor space exists between the perforated portion and the second inner wall surface of the housing.

2. The heat spreading device according to claim 1 , wherein the support portion has a tapered shape whose width narrows from the perforated portion toward the first inner wall surface.

3. 3. The heat spreading device according to claim 1, wherein when the perforated portion is viewed in the thickness direction, no holes are present in the perforated portion in an area overlapping with the support portion.

4. 3. The heat spreading device of claim 1, wherein the thickness of the support portion is the same as or smaller than the thickness of the perforated portion.

5. The heat spreading device according to claim 1 , wherein the support portion includes a plurality of columnar members.

6. The heat spreading device of claim 1 , wherein the support portion includes a plurality of rail-shaped members.

7. An electronic device comprising the heat spreading device according to claim 1 or 2.

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