Heat diffusion device and electronic apparatus

Abstract

A vapor chamber 1, which is one embodiment of this heat diffusion device, comprises: a housing 10 which has a first inner surface 11a and a second inner surface 12a that face one another in a thickness direction Z and which is provided with an internal space; an operating medium 20 sealed in the internal space of the housing 10; and a sheet-shaped wick 30 disposed in the internal space of the housing 10. The wick 30 is provided with a plurality of through holes 60 penetrating in the sheet thickness direction of the wick 30. The wick 30 includes a plurality of hollow protruding portions 65 that approach the first inner surface 11a of the housing 10 in the thickness direction Z of the housing 10. The plurality of through holes 60 include a protruding portion through hole 60A provided in one of the plurality of protruding portions 65. Protrusions 70 protruding in the sheet thickness direction of the wick 30 are provided on peripheries of the protruding portion through holes 60A.

Description

Heat diffusion devices and electronic devices

[0001] The present invention relates to a heat spreading device and an electronic device.

[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 and a wick that transports the working medium by capillary force are sealed 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 heat diffusion device comprising a housing having a first inner wall surface and a second inner wall surface that face each other in the thickness direction, a working medium sealed in the internal space of the housing, and a wick arranged in the internal space of the housing, wherein the wick includes a support body that contacts the first inner wall surface and a perforated body that contacts the support body, the perforated body having a through hole that penetrates in the thickness direction, and a protrusion provided on the periphery of the through hole in a direction close to the second inner wall surface.

[0005] International Publication No. 2023 / 145396

[0006] In the heat diffusion device described in Patent Document 1, although the wick support contacts the inner surface of the housing, there are few contact points between the wick and the inner surface of the housing. Furthermore, when comparing the volumetric percentage of the wick to the volumetric percentage of the working medium in the entire heat diffusion device, the working medium accounts for a larger percentage. For these reasons, heat is not easily transferred throughout the working medium, and evaporation of the working medium on the top surface of the wick is likely to be suppressed. As a result, there is a risk of deterioration of the gas-liquid circulation of the heat diffusion device.

[0007] The present invention has been made to solve the above problems, and aims to provide a heat spreading device with excellent heat transferability. Another aim of the present invention is to provide an electronic device equipped with the heat spreading device.

[0008] 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 disposed in the internal space of the housing. The wick has a plurality of through-holes penetrating the wick in the sheet thickness direction. The wick includes a plurality of hollow protrusions that approach the first inner surface of the housing in the thickness direction of the housing. The plurality of through-holes includes a protrusion through-hole provided in one of the plurality of protrusions. A protrusion that protrudes in the sheet thickness direction of the wick is provided on the periphery of the protrusion through-hole.

[0009] An electronic device of the present invention includes the heat spreading device of the present invention.

[0010] According to the present invention, it is possible to provide a heat spreading device having excellent heat transferability, and further, it is possible to provide an electronic device including the heat spreading device.

[0011] FIG. 1 is a perspective view schematically illustrating an example of a heat diffusing device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically illustrating an example of a heat diffusing device according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating an example of a housing and a wick constituting the heat diffusing device according to the first embodiment of the present invention. FIG. 4 is a perspective view schematically illustrating an example of a protrusion included in a wick constituting the heat diffusing device according to the first embodiment of the present invention. FIG. 5 is a schematic diagram for explaining the effects of the heat diffusing device according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view schematically illustrating an example of a shape of a protrusion. FIG. 7 is a cross-sectional view schematically illustrating another example of a shape of a protrusion. FIG. 8 is a plan view schematically illustrating an example of a wick shown in FIG. 3. FIG. 9 is a plan view schematically illustrating another example of the wick shown in FIG. 3. FIG. 10 is a plan view schematically illustrating an example of a heat diffusing device in which a wick including rail-shaped protrusions is arranged. FIG. 11 is a plan view schematically illustrating another example of a heat diffusing device in which a wick including rail-shaped protrusions is arranged. 12 is a cross-sectional view showing an example of a housing and a wick constituting the heat spreading device according to the second embodiment of the present invention, and FIG. 13 is a perspective view showing an example of a protrusion included in the wick constituting the heat spreading device according to the second embodiment of the present invention.

[0012] 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.

[0013] 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.

[0014] In the following description, unless otherwise specified, each embodiment will be simply referred to as the "heat spreading device of the present invention."

[0015] A vapor chamber will be described below as an example of one embodiment of the heat spreading device of the present invention. The heat spreading device of the present invention can also be applied to heat spreading devices such as heat pipes.

[0016] 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.

[0017] 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 included. Furthermore, in this specification, "same" or "constant" is not an expression that means only when something is completely the same or constant, but is an expression that means that when something is substantially the same or constant, a difference of about a few percent, for example, is included.

[0018] First Embodiment In a first embodiment of the present invention, a convex portion provided on the periphery of the protrusion through-hole protrudes outward from the protrusion in the sheet thickness direction of the wick.

[0019] 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 a first embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II of the heat diffusion device shown in Fig. 1.

[0020] 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. As shown in Figure 2, 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.

[0021] 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.

[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 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.

[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 set appropriately depending on the application. The width and length of the vapor chamber 1 are, for example, 5 mm to 500 mm, 20 mm to 300 mm, or 50 mm to 200 mm. The width and length of the vapor chamber 1 may be the same or different.

[0024] 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.

[0025] 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.

[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 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.

[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 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.

[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 to 500 μm. The height of the internal space of the housing 10 is not particularly limited, but is preferably 30 μm to 400 μm.

[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 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.

[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 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.

[0032] The wick 30 has a capillary structure that allows the working medium 20 to move by capillary force.

[0033] 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.

[0034] 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.

[0035] The thickness of the wick 30 is not particularly limited, but is, for example, 5 μm or more and 50 μm or less.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The height of the support pillars 40 in one vapor chamber may be the same or different. The height of the support pillars 40 is, for example, 50 μm or more and 1000 μm or less.

[0041] 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 5000 μm or less.

[0042] 2, the width of the support 40 is not particularly limited as long as it provides 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 to 2000 μm, and preferably 300 μm to 1000 μm. Increasing the equivalent circle diameter of the support 40 can further suppress deformation of the housing 10. On the other hand, decreasing the equivalent circle diameter of the support 40 can ensure a larger space for the vapor of the working medium 20 to move.

[0043] As shown in FIG. 2, the wick 30 is provided with a plurality of through holes 60 that penetrate the wick 30 in the sheet thickness direction.

[0044] The working medium 20 can move by capillary action in the through-holes 60. The shape of the through-holes 60 is not particularly limited, but it is preferable that the cross section of the wick 30 perpendicular to the sheet thickness direction is circular or elliptical.

[0045] The arrangement of the through holes 60 is not particularly limited, but is preferably arranged evenly in a predetermined region, more preferably evenly over the entire area, for example, so that the center-to-center distance (pitch) between adjacent through holes 60 is constant.

[0046] The through-holes 60 can be formed, for example, by punching the metal foil that constitutes the wick 30 using a press process.

[0047] Furthermore, the wick 30 includes a plurality of protrusions 65 that approach the first inner surface 11a of the housing 10 in the thickness direction Z of the housing 10. The protrusions 65 are hollow and have cavities. The protrusions 65 are formed in recessed portions of the wick 30.

[0048] 3 is a cross-sectional view showing an example of a housing and a wick constituting the heat spreading device according to the first embodiment of the present invention, and FIG. 4 is a perspective view showing an example of a protrusion included in the wick constituting the heat spreading device according to the first embodiment of the present invention.

[0049] 3 and 4, the plurality of through holes 60 includes a protrusion through-hole 60A provided in one of the plurality of protrusions 65. The number of protrusions 65 provided with a protrusion through-hole 60A is not particularly limited, and may be one, or two or more. Also, some protrusions 65 may not have a protrusion through-hole 60A provided therein.

[0050] The number, position, size, shape, etc. of the protrusion through-holes 60A are not particularly limited. For example, the wick 30 may include a protrusion 65 having one protrusion through-hole 60A, or may include a protrusion 65 having multiple protrusion through-holes 60A. The protrusion through-hole 60A may be provided on the tip surface of the protrusion 65, or on the side surface of the protrusion 65.

[0051] A protrusion 70 protruding in the sheet thickness direction of the wick 30 is provided on the periphery of the protrusion through-hole 60A. The number of protrusion through-holes 60A having a protrusion 70 is not particularly limited, and may be one or more. Also, there may be protrusion through-holes 60A without a protrusion 70.

[0052] The protrusion 70 may be provided only on a part of the periphery of the protrusion through-hole 60A, but is preferably provided on the entire periphery of the protrusion through-hole 60A.

[0053] In the vapor chamber 1 shown in Figure 3, as shown in Figures 3 and 4, the convex portion 70 provided on the periphery of the protrusion portion through hole 60A protrudes outward from the protrusion portion 65 in the sheet thickness direction of the wick 30.

[0054] FIG. 5 is a schematic diagram for explaining the function and effect of the heat spreading device according to the first embodiment of the present invention.

[0055] When the protrusions 70 are provided on the periphery of the protrusion through-holes 60A, the surface area of ​​the wick 30 increases by the amount of the protrusions 70. Therefore, heat is more easily transferred to the working medium 20 around the wick 30, and evaporation EV of the working medium 20 on the top surface of the wick 30 is promoted. As a result, the heat H from the heat source HS ０ The transmission of information is improved.

[0056] Furthermore, when the protrusions 70 provided on the periphery of the protrusion through-hole 60A protrude outward from the protrusions 65 in the sheet thickness direction of the wick 30, the distance D between adjacent protrusions 65 becomes shorter than when the protrusions 70 are not provided on the periphery of the protrusion through-hole 60A. As a result, the capillary pressure P Ｃ contributes more easily, improving the liquid transportability.

[0057] The protrusion through-hole 60A having the convex portion 70 is preferably provided at a position that does not contact the first inner surface 11a of the housing 10. Therefore, the protrusion through-hole 60A having the convex portion 70 is preferably provided on the side surface of the protrusion 65. Note that the protrusion 65 may include the protrusion through-hole 60A having the convex portion 70 at a position that contacts the first inner surface 11a of the housing 10.

[0058] As shown in FIGS. 3 and 4, the plurality of through-holes 60 may include non-protrusion through-holes 60B provided outside the protrusions 65.

[0059] When non-protrusion through holes 60B are provided in addition to the protrusions 65, the number, position, size, shape, etc. of the non-protrusion through holes 60B are not particularly limited. For example, the diameter of the non-protrusion through holes 60B may be the same as the diameter of the protrusion through holes 60A, may be larger than the diameter of the protrusion through holes 60A, or may be smaller than the diameter of the protrusion through holes 60A. Furthermore, the shape of the non-protrusion through holes 60B may be the same as or different from the shape of the protrusion through holes 60A.

[0060] When non-protrusion through holes 60B are provided in addition to the protrusions 65, the periphery of the non-protrusion through holes 60B may be provided with convex portions 80 that protrude in the sheet thickness direction of the wick 30. Providing convex portions 80 on the periphery of the non-protrusion through holes 60B improves the performance of the wick 30. The number of non-protrusion through holes 60B having convex portions 80 is not particularly limited, and may be one or more. Furthermore, non-protrusion through holes 60B having convex portions 80 and non-protrusion through holes 60B without convex portions 80 may be mixed.

[0061] When a protrusion 80 is provided on the periphery of the non-protrusion through-hole 60B, the height of the protrusion 80 is preferably smaller than the height of the protrusion 65.

[0062] When a protrusion 80 is provided on the periphery of the non-protrusion through-hole 60B, the protrusion 80 may be provided so as to protrude toward the first inner surface 11a of the housing 10 (the lower side in FIG. 3 ), or may be provided so as to protrude toward the second inner surface 12a of the housing 10 (the upper side in FIG. 3 ). A mixture of protrusions 80 protruding toward the first inner surface 11a of the housing 10 and protrusions 80 protruding toward the second inner surface 12a of the housing 10 may be present.

[0063] When a convex portion 80 is provided on the periphery of the non-protrusion through hole 60B, the convex portion 80 may be provided only on a part of the periphery of the non-protrusion through hole 60B, but it is preferable that the convex portion 80 is provided on the entire periphery of the non-protrusion through hole 60B.

[0064] The convex portion 70 of the protrusion through-hole 60A or the convex portion 80 of the non-protrusion through-hole 60B can be formed, for example, by punching the metal foil that constitutes the wick 30 using a press process. In this case, the convex portion 70 or the convex portion 80 may be formed simultaneously with the through-hole 60, or may be formed separately from the through-hole 60. In punching using a press process, the shape of the convex portion 70 or the convex portion 80 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.

[0065] The dimensions of the protrusions 70 or 80 are not particularly limited, and for example, the height of the protrusions 70 or 80 may be greater than, smaller than, or the same as the diameter of the through-hole 60. The height of the protrusions 70 may be the same as, greater than, or smaller than the height of the protrusions 80.

[0066] There is no particular limitation on the shape of the protrusions 70 or the protrusions 80. The shape of the protrusions 70 may be the same as the shape of the protrusions 80, or may be different.

[0067] FIG. 6 is a cross-sectional view schematically showing an example of the shape of the convex portion.

[0068] As shown in Fig. 6 , the distance between the outer walls of the protrusions 70 or 80 may narrow toward the tip of the protrusions 70 or 80 (toward the upper side in Fig. 6 ). That is, the protrusions 70 or 80 may have a tapered shape. In this case, the protrusions 70 or 80 may have a convex shape toward the tip side of the protrusions 70 or 80 (upper side in Fig. 6 ) in a cross section along the thickness direction, or may have a convex shape toward the base end side of the protrusions 70 or 80 (lower side in Fig. 6 ).

[0069] FIG. 7 is a cross-sectional view schematically showing another example of the shape of the convex portion.

[0070] As shown in FIG. 7 , the protrusion 70 or the protrusion 80 may have a lid portion at the tip that narrows the through-hole 60 .

[0071] Although not shown, the distance between the outer walls of the protrusions 70 or 80 may increase toward the tip of the protrusions 70 or 80. That is, the protrusions 70 or 80 may have an inverse tapered shape. In this case, the protrusions 70 or 80 may have a convex shape toward the tip side of the protrusions 70 or 80 in a cross section along the thickness direction, or may have a convex shape toward the base end side of the protrusions 70 or 80. The protrusions 70 or 80 may have a lid portion at their tip that narrows the through hole 60.

[0072] Alternatively, the distance between the outer walls of the protrusions 70 or 80 may be constant toward the tip of the protrusions 70 or 80. In this case, the protrusions 70 or 80 may have a lid portion at the tip that narrows the through-hole 60.

[0073] The protrusion 65 may or may not be in contact with the first inner surface 11 a of the housing 10. When the protrusion 65 is in contact with the first inner surface 11 a, the protrusion 65 may or may not be bonded to the first inner surface 11 a.

[0074] FIG. 8 is a plan view schematically illustrating an example of the wick shown in FIG.

[0075] 8, the protrusion 65 includes, for example, a plurality of columnar members. 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.

[0076] The liquid phase working medium 20 is held between the protrusions 65. This can improve the heat transport performance of a heat diffusion device such as a vapor chamber.

[0077] FIG. 9 is a plan view schematically showing another example of the wick shown in FIG. 3 .

[0078] 9, the protrusion 65 may include a plurality of rail-shaped members. 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. When the protrusion 65 is rail-shaped (linear), the strength of the wick as a support for maintaining the space of the liquid flow path is higher than when the protrusion 65 is columnar.

[0079] 10 and 11 are plan views schematically illustrating an example of a heat diffusion device in which a wick having rail-shaped protrusions is disposed.

[0080] As in the vapor chamber 1 shown in Figure 10, the rail-shaped (linear) protrusions 65 are preferably arranged along the direction in which the liquid working fluid returns toward the heat source HS (evaporator) (the direction indicated by the arrow in Figure 10). The same applies to cases where the planar shape of the housing is not rectangular, as in the vapor chamber 1A shown in Figure 11. In this case, the liquid working fluid is less likely to flow in a direction perpendicular to the direction of movement of the liquid working fluid (for example, the left-right direction in Figure 10), thereby improving liquid transport performance.

[0081] When the protrusion 65 includes a plurality of columnar members, the shape of the protrusion 65 is not particularly limited, but examples thereof include a cylindrical shape, an elliptical cylindrical shape, a rectangular prism shape, a truncated cone shape, and a truncated pyramid shape.

[0082] When the protrusion portion 65 includes multiple rail-shaped members, the cross-sectional shape perpendicular to the extension direction of the protrusion portion 65 is not particularly limited, but examples include polygonal shapes such as a square, a semicircular shape, a semi-elliptical shape, and shapes combining these.

[0083] 2 and the like, the protrusions 65 may have a tapered shape that narrows toward the first inner surface 11a of the housing 10. This allows the flow path between the protrusions 65 to be widened on the housing 10 side.

[0084] The height of the protrusions 65 may be the same or different in one vapor chamber. The height of the protrusions 65 is, for example, 10 μm or more and 100 μm or less. The height of the protrusions 65 is preferably smaller than the height of the support 40.

[0085] The arrangement of the protrusions 65 is not particularly limited, but is preferably arranged evenly in a predetermined region, more preferably evenly over the entire surface, for example, so that the center-to-center distance (pitch) between adjacent protrusions 65 is constant.

[0086] The center-to-center distance between the protrusions 65 is, for example, 60 μm or more and 800 μm or less. The center-to-center distance between the protrusions 65 is preferably smaller than the center-to-center distance between the support columns 40.

[0087] The equivalent circle diameter of the cross section perpendicular to the height direction of the wick 30 side end of the protrusion 65 is, for example, 20 μm or more and 500 μm or less. The equivalent circle diameter of the cross section perpendicular to the height direction of the wick 30 side end of the protrusion 65 is preferably smaller than the equivalent circle diameter of the cross section perpendicular to the height direction of the wick 30 side end of the support 40.

[0088] The method for forming the protrusions 65 is not particularly limited, but for example, a hollow protrusion 65 can be formed in the recessed portion by bending and recessing a part of the metal foil that constitutes the wick 30 by processing such as pressing. A vapor space is formed in the recessed portion of the protrusion 65, improving thermal conductivity.

[0089] For example, by performing press working to form the through holes 60 and then performing processing to form the protrusions 65, it is possible to provide the through holes 60 in the protrusions 65, and also to provide the through holes 60 in areas other than the protrusions 65. Alternatively, the press working to form the protrusions 65 and the press working to form the through holes 60 may be performed simultaneously.

[0090] It is preferable that the thickness of the metal foil is constant before processing such as press working. However, the metal foil may become thinner in the bent portion. Therefore, as shown in the example in Figure 3, it is preferable that the thickness of the protrusions 65 is the same as or smaller than the thickness of the wick 30 other than the protrusions 65.

[0091] 3 and 4, the center-to-center distance between the plurality of protrusions 65 is preferably greater than the center-to-center distance between the plurality of through holes 60. The center-to-center distance between the through holes 60 is, for example, not less than 3 μm and not more than 150 μm.

[0092] The diameter of the through-hole 60 is, for example, 100 μm or less. When the diameter of the through-hole 60 varies in the thickness direction Z, the diameter of the smallest portion is defined as the diameter of the through-hole 60.

[0093] A vapor space through which vapor of the working medium 20 moves is formed between the wick 30 and the second inner surface 12a of the housing 10. From the viewpoint of forming a liquid flow path while ensuring a sufficient vapor space, it is preferable that the distance between the wick 30 and the first inner surface 11a of the housing 10 in the thickness direction Z of the housing 10 be smaller than the distance between the wick 30 and the second inner surface 12a of the housing 10, as shown in FIG.

[0094] Second Embodiment In a second embodiment of the present invention, a convex portion provided on the periphery of the protrusion through-hole protrudes inward from the protrusion in the sheet thickness direction of the wick.

[0095] 12 is a cross-sectional view showing an example of a housing and a wick constituting the heat spreading device according to the second embodiment of the present invention, and FIG. 13 is a perspective view showing an example of a protrusion included in the wick constituting the heat spreading device according to the second embodiment of the present invention.

[0096] In the vapor chamber 2 shown in Figure 12, as shown in Figures 12 and 13, the convex portion 70 provided on the periphery of the protrusion portion through hole 60A protrudes inward from the protrusion portion 65 in the sheet thickness direction of the wick 30.

[0097] Even when the protrusions 70 provided on the periphery of the protrusion through-holes 60A protrude inward from the protrusions 65 in the sheet thickness direction of the wick 30, the surface area of ​​the wick 30 increases by the amount of the protrusions 70. Therefore, similar to the first embodiment, heat transfer is improved.

[0098] The vapor chamber 2 shown in FIG. 12 has a common configuration with the vapor chamber 1 shown in FIG. 3 except for the direction in which the convex portion 70 protrudes.

[0099] [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.

[0100] In the heat diffusion device of the present invention, protrusion through-holes having convex portions protruding outward from the protrusions in the sheet thickness direction of the wick may be mixed with protrusion through-holes having convex portions protruding inward from the protrusions in the sheet thickness direction of the wick. In this case, the protrusion through-holes having convex portions protruding outward and the protrusion through-holes having convex portions protruding inward may be provided on separate protrusions or on the same protrusion.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The present specification discloses the following:

[0106] <1> A heat diffusion device comprising: 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 a plurality of through holes penetrating in the sheet thickness direction of the wick, the wick includes a plurality of hollow protrusions approaching the first inner surface of the housing in the thickness direction of the housing, the plurality of through holes including a protrusion through hole provided in one of the plurality of protrusions, and a protrusion protruding in the sheet thickness direction of the wick is provided on the periphery of the protrusion through hole.

[0107] <2> The heat diffusion device according to <1>, wherein the protrusions provided on the periphery of the protrusion through-holes protrude outward from the protrusions in the sheet thickness direction of the wick.

[0108] <3> The heat diffusion device according to <1>, wherein the protrusions provided on the periphery of the protrusion through-holes protrude inward from the protrusions in the sheet thickness direction of the wick.

[0109] <4> The heat spreading device according to any one of <1> to <3>, wherein the protrusion through-hole having the convex portion is provided at a position that does not contact the first inner surface of the housing.

[0110] <5> The heat spreading device according to any one of <1> to <4>, wherein the plurality of through holes include non-protrusion through holes provided outside the protrusions.

[0111] <6> The heat diffusion device according to <5>, wherein a protrusion protruding in a sheet thickness direction of the wick is provided on the periphery of the non-protrusion through-hole.

[0112] <7> An electronic device comprising the heat diffusion device according to any one of <1> to <6>.

[0113] The heat spreading device of the present invention can be used in a wide range of applications in the field of mobile information terminals, etc. For example, it can be used to lower the temperature of heat sources such as CPUs and extend the operating time of electronic devices, and can be used in smartphones, tablet terminals, laptop computers, etc.

[0114] REFERENCE SIGNS LIST 1, 1A, 2 Vapor chamber (heat diffusion device) 10 Housing 11 First sheet 11a First inner surface 12 Second sheet 12a Second inner surface 20 Working medium 30 Wick 40 Support 60 Through-hole 60A Projection portion through-hole 60B Non-projection portion through-hole 65 Projection portion 70, 80 Convex portion HS Heat source X Width direction Y Length direction Z Thickness direction

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 a plurality of through holes penetrating in the sheet thickness direction of the wick, the wick has a plurality of hollow protrusions approaching the first inner surface of the housing in the thickness direction of the housing, the plurality of through holes including a protrusion through hole provided in one of the plurality of protrusions, and a protrusion protruding in the sheet thickness direction of the wick is provided on the periphery of the protrusion through hole.

2. The heat diffusion device according to claim 1, wherein the protrusions provided on the periphery of the protrusion through-holes protrude outward from the protrusions in the sheet thickness direction of the wick.

3. The heat diffusion device according to claim 1, wherein the protrusions provided on the periphery of the protrusion through-holes protrude inward from the protrusions in the sheet thickness direction of the wick.

4. A heat spreading device according to any one of claims 1 to 3, wherein the protrusion through-hole having the convex portion is provided at a position that does not contact the first inner surface of the housing.

5. A heat spreading device according to any one of claims 1 to 4, wherein the plurality of through holes include non-protrusion through holes provided outside the protrusions.

6. The heat diffusion device according to claim 5, wherein a protrusion protruding in the sheet thickness direction of the wick is provided on the periphery of the non-protrusion through-hole.

7. An electronic device comprising the heat spreading device according to any one of claims 1 to 6.

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