Heat diffusion device

Abstract

A heat diffusion device (1) has a housing (100), and a working medium and a wick (200) disposed in an internal space of the housing (100). The housing (100) has a top face (10) and a bottom face (20) having a first bottom face (21) and a second bottom face (22) opposite the top face (10) in the thickness direction. A step (23) is provided between the first bottom face (21) and the second bottom face (22). The minimum distance between the top face (10) and the first bottom face (21) is smaller than the minimum distance between the top face (10) and the second bottom face (22). The step (23) has a first step face (23a) parallel to a first direction orthogonal to the thickness direction, a second step face (23b) parallel to the first direction, and a first connection step face (23c) that is not parallel to the first direction and connects together an end part of the first step face (23a) and an end part of the second step face (23b) in the first direction. The wick (200) has a first part (200A) that continuously covers the first bottom face (21), the first step face (23a), and the second bottom face (22) of the housing (100) along a second direction orthogonal to the thickness direction and to the first direction, and a second part (200B) that continuously covers the first bottom face (21), the second step face (23b), and the second bottom face (22) of the housing (100) along the second direction. Between a portion of the first part (200A) of the wick (200) that covers the first bottom face (21) of the housing (100) and a portion of the second part (200B) of the wick (200) that covers the second bottom face (22), a non-continuous part where the wick (200) is not continuous in the first direction is provided along the first connection step face (23c).

Description

Thermal diffusion devices

[0001] This invention relates to a thermal diffusion device.

[0002] In recent years, the increased integration and performance of components have led to a rise in heat generation. Furthermore, the miniaturization of products has increased heat density. This situation is particularly pronounced in the field of mobile devices such as smartphones and tablets. For these reasons, heat dissipation measures have become crucial.

[0003] While graphite sheets and similar materials are often used for heat dissipation, their heat transport capacity is insufficient. Therefore, the use of various heat diffusion devices (e.g., vapor chambers) capable of diffusing heat is being considered.

[0004] Since circuit boards equipped with heat sources also contain other electronic components, it is sometimes necessary to prevent physical interference between these other electronic components and heat dissipation devices.

[0005] Methods to prevent physical interference between other electronic components and the heat diffusion device include changing the planar shape of the heat diffusion device so that it does not overlap with other electronic components when viewed from the thickness direction, or placing a metal pad or the like between the heat source and the heat diffusion device to slightly separate (float) the heat diffusion device from the substrate.

[0006] However, methods that modify the planar shape of the heat diffusion device have the problem of reducing heat transport capacity because the movement path of the working medium becomes longer. Also, in methods that place a metal pad between the heat source and the heat diffusion device, the heat transport capacity of the metal pad is insufficient, so the heat transport capacity of the metal pad becomes a bottleneck, and the overall heat transport capacity is reduced.

[0007] In addition to the methods described above, another proposed method involves making the housing of the heat diffusion device itself stepped to prevent interference with other electronic components. For example, Patent Document 1 discloses a heat diffusion device with a stepped housing shape.

[0008] International Publication No. 2024 / 001199

[0009] However, when the enclosure has a stepped shape, there is a problem in that it is difficult to arrange the wick without gaps on the bottom surface of the enclosure. In a typical vapor chamber, the wick is manufactured as a sheet-like component separately from the enclosure and then attached to the enclosure. However, if the enclosure has steps, wrinkles, distortions, or tears may occur in the wick at the stepped areas, making it impossible to arrange the wick without gaps on the enclosure. Areas where the wick is not arranged without gaps have a reduced capacity to transport the working medium, so if wrinkles, distortions, or tears occur in the wick at the stepped areas, the maximum heat transport capacity characteristics of the vapor chamber will decrease.

[0010] This invention was made to solve the above problems and aims to provide a heat diffusion device that does not experience a decrease in maximum heat transport characteristics even when there are steps in the housing.

[0011] The present invention provides a thermal diffusion device comprising a housing, a wick and a working medium disposed in the internal space of the housing, wherein the housing has a top surface and a bottom surface having a first bottom surface and a second bottom surface facing the top surface in the thickness direction, a step is provided between the first bottom surface and the second bottom surface, the minimum distance between the top surface and the first bottom surface is smaller than the minimum distance between the top surface and the second bottom surface, the step comprises a first stepped surface parallel to a first direction perpendicular to the thickness direction, a second stepped surface parallel to the first direction, and a connection between the end of the first stepped surface and the end of the second stepped surface in the first direction. The wick has a first connecting stepped surface that is not parallel to the first direction, and the wick has a first part that continuously covers the first bottom surface, the first stepped surface, and the second bottom surface of the housing along a second direction perpendicular to the thickness direction and the first direction, and a second part that continuously covers the first bottom surface, the second stepped surface, and the second bottom surface of the housing along the second direction, and a discontinuity is provided between the portion of the first part of the wick that covers the first bottom surface of the housing and the portion of the second part of the wick that covers the second bottom surface, along the first connecting stepped surface, the wick is not continuous in the first direction.

[0012] According to the present invention, it is possible to provide a thermal diffusion device that does not experience a decrease in maximum heat transport characteristics even when there are steps in the housing.

[0013] Figure 1 is a schematic perspective view showing an example of the heat diffusion device of the present invention. Figure 2 is a schematic diagram showing the positional relationship between the bottom surface of the housing and the wick that constitute the heat diffusion device shown in Figure 1. Figure 3 is a top view of the housing shown in Figure 2. Figure 4 is a diagram showing the first bottom surface A, first bottom surface B, second bottom surface A, and second bottom surface B of the housing shown in Figure 3, with different hatching. Figure 5 is an external perspective view of the bottom surface of the housing shown in Figure 2. Figure 6 is a cross-sectional view taken along line VI-VI of the heat diffusion device shown in Figure 1. Figure 7 is a cross-sectional view taken along line VII-VII of the heat diffusion device shown in Figure 1. Figure 8 is a schematic perspective view showing a sheet-like wick that constitutes the heat diffusion device shown in Figure 1. Figure 9 is a perspective view showing the sheet-like wick shown in Figure 8 after it has been folded. Figure 10 is a schematic perspective view showing an example of a second sheet-like wick. Figure 11 is a perspective view showing the second sheet-like wick shown in Figure 10 after it has been folded. Figure 12 is a schematic perspective view showing another example of a sheet-like wick. Figure 13 is a perspective view showing the sheet-like wick shown in Figure 12 after it has been folded. Figure 14 is a schematic perspective view showing yet another example of a sheet-like wick. Figure 15 is a schematic perspective view showing yet another example of a sheet-like wick. Figure 16 is a top view showing another example of a housing. Figure 17 is a schematic perspective view showing an example of a sheet-like wick that can be used in the housing shown in Figure 16. Figure 18 is a top view showing yet another example of a housing. Figure 19 is a top view showing yet another example of a housing. Figure 20 is a top view showing yet another example of a housing. Figure 21 is a top view showing yet another example of a housing. Figure 22 is a top view showing yet another example of a housing. Figure 23 is a top view showing yet another example of a housing. Figure 24 is a top view showing yet another example of the enclosure.

[0014] The thermal diffusion device of the present invention will be described below. However, the present invention is not limited to the configuration described below, and may be modified as appropriate without departing from the spirit of the invention. Furthermore, a combination of several of the preferred configurations described below also constitutes the present invention.

[0015] The following diagrams are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product. The same reference numerals are used for identical or equivalent parts in the diagrams. Furthermore, identical elements are denoted by the same reference numerals in each diagram, and redundant explanations are omitted.

[0016] In this specification, terms describing relationships between elements (e.g., "opposite," "parallel," "orthogonal," etc.) and terms describing the shapes of elements mean not only their literal and precise forms, but also a range that is substantially equivalent, for example, a range that includes differences of a few percent.

[0017] The embodiments described below are illustrative, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. In the description of each embodiment, descriptions of matters common to embodiments already described will be omitted, and only the differences will be described. In particular, similar effects and advantages due to similar configurations will not be mentioned sequentially for each embodiment.

[0018] [Thermal Diffusion Device] The thermal diffusion device of the present invention is a thermal diffusion device comprising a housing, a wick and a working medium disposed in the internal space of the housing, wherein the housing has a top surface and a bottom surface having a first bottom surface and a second bottom surface facing the top surface in the thickness direction, a step is provided between the first bottom surface and the second bottom surface, the minimum distance between the top surface and the first bottom surface is smaller than the minimum distance between the top surface and the second bottom surface, the step comprises a first stepped surface parallel to a first direction perpendicular to the thickness direction, a second stepped surface parallel to the first direction, and the end of the first stepped surface and the end of the second stepped surface in the first direction The wick has a first connecting stepped surface that is not parallel to the first direction, and the wick has a first part that continuously covers the first bottom surface, the first stepped surface, and the second bottom surface of the housing along a second direction perpendicular to the thickness direction and the first direction, and a second part that continuously covers the first bottom surface, the second stepped surface, and the second bottom surface of the housing along the second direction, and a discontinuity is provided between the portion of the first part of the wick that covers the first bottom surface of the housing and the portion of the second part of the wick that covers the second bottom surface, along the first connecting stepped surface, the wick is not continuous in the first direction.

[0019] Figure 1 is a schematic perspective view showing an example of the heat diffusion device of the present invention. As shown in Figure 1, the heat diffusion device 1 comprises a housing 100, a wick 200 and a working medium (not shown) arranged in the internal space of the housing.

[0020] The housing 100 is provided with an evaporation section for evaporating the enclosed working medium. Preferably, the evaporation section is located on the bottom surface of the housing 100. A heat source, which is a heat-generating element, is arranged on the outer surface of the housing 100. Examples of heat sources include electronic components of electronic equipment, such as a central processing unit (CPU). The part of the internal space of the housing 100 that is near the heat source and heated by the heat source corresponds to the evaporation section.

[0021] It is more preferable that the evaporation section be located on the second bottom surface of the housing 100, which will be described later. The evaporation section may be located on only a part of the second bottom surface, or on the entire second bottom surface.

[0022] The housing 100 is preferably composed of opposing first and second sheets whose outer edges are joined together. In this case, the first sheet constitutes the top surface of the housing, and the second sheet constitutes the bottom surface of the housing.

[0023] When the housing 100 is composed of a first sheet and a second sheet, the materials constituting the first sheet and the second sheet are not particularly limited, as long as they have properties suitable for use as a heat diffusion device such as a vapor chamber, such as thermal conductivity, strength, flexibility, and pliability. The materials constituting the first sheet and the second sheet are preferably metals, such as copper, nickel, aluminum, magnesium, titanium, iron, or alloys mainly composed of these, and are particularly preferably copper. The materials constituting the first sheet and the second sheet may be the same or different, but are preferably the same.

[0024] When the housing 100 is composed of a first sheet and a second sheet, the first sheet and the second sheet are joined to each other at their outer edges. The method of 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.

[0025] The direction in which the first and second sheets face each other is the thickness direction.

[0026] The thickness of the first and second sheets is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 30 μm to 100 μm, and even more preferably 40 μm to 60 μm, respectively. The thicknesses of the first and second sheets may be the same or different. Furthermore, the thickness of each sheet of the first and second sheets may be the same throughout, or a portion may be thinner.

[0027] The shapes of the first and second sheets are not particularly limited, as long as the internal space has a stepped shape as described later. For example, the first and second sheets may each have an outer edge that is thicker than the rest of the sheet.

[0028] The maximum thickness of the thermal diffusion device 1 is not particularly limited, but is preferably 50 μm or more and 500 μm or less. The maximum thickness of the entire thermal diffusion device is the maximum thickness of the thermal diffusion device, including the thickness of the first sheet and the second sheet in the thickness direction. Generally, the thickness of the thermal diffusion device is the distance between the first sheet and the second sheet in the thickness direction plus the thickness of the first sheet and the second sheet.

[0029] The shape of the housing 100 as viewed from the thickness direction (plan view shape) is not particularly limited, but it is preferably a substantially rectangular shape consisting of a first side surface and a second side surface facing a first direction perpendicular to the thickness direction, and a third side surface and a fourth side surface facing a second direction perpendicular to both the thickness direction and the first direction.

[0030] The working medium is not particularly limited as long as it can undergo a gas-liquid phase change in the environment inside the housing 100, and can be, for example, water, alcohols, alternative fluorocarbons, etc. For example, the working medium is an aqueous compound, preferably water.

[0031] The wick 200 has a capillary structure that allows the working medium to be moved by capillary force.

[0032] The material constituting the wick 200 is not particularly limited, but is preferably a metal, such as copper, nickel, aluminum, magnesium, titanium, iron, or alloys mainly composed of these, and is particularly preferably copper. The material constituting the wick 200 may be the same as or different from the material constituting the housing 100.

[0033] The material constituting the wick 200 may be a porous body. When the wick 200 is made of a porous body, the surface area of ​​the wick 200 increases, and therefore the area of ​​the evaporation surface, which is the part of the surface of the wick 200 where the working medium evaporates, also increases. Examples of porous bodies include metal porous films formed by etching or metalworking, meshes, nonwoven fabrics, sintered bodies, and other porous bodies. Meshes may be made of, for example, metal meshes, resin meshes, or surface-coated meshes thereof, and are preferably made of copper meshes, stainless steel meshes, or polyester meshes. Sintered bodies may be made of, for example, metal porous sintered bodies or ceramic porous sintered bodies, and are preferably copper or nickel porous sintered bodies. Other porous bodies include, for example, metal porous bodies, ceramic porous bodies, and resin porous bodies. Meshes, nonwoven fabrics, and sintered bodies are also included as porous bodies in this specification.

[0034] The size and shape of the wick 200 are not particularly limited as long as it is in sheet form, but it is preferable that the wick 200 be arranged to continuously cover the entire bottom surface within the internal space of the housing 100.

[0035] Support columns may be placed in the internal space of the housing 100 between the top surface and the wick. By placing support columns in the internal space of the housing 100, it is possible to support the housing 100 and the wick 200.

[0036] The material constituting the support column is not particularly limited, but examples include resin, metal, ceramics, or mixtures thereof, laminates, etc. The support column may also be integral with the housing 100, and may be formed, for example, by etching the inside of the first sheet which forms the top surface of the housing 100.

[0037] The shape of the support column is not particularly limited as long as it can support the housing 100 and the wick 200, but examples of cross-sectional shapes perpendicular to the height direction of the support column include polygons such as rectangles, circles, ellipses, etc.

[0038] The support columns may have a tapered shape, narrowing in width from the top surface of the housing 100 towards the wick 200. This allows for a wider flow path between the support columns on the wick 200 side.

[0039] Figure 2 schematically shows the positional relationship between the bottom surface of the housing and the wick that constitute the heat diffusion device shown in Figure 1. Note that Figure 2 is shown with the top surface 10 transparent in order to explain the shape of the internal space of the housing 100.

[0040] As shown in Figure 2, the heat diffusion device 1 consists of a housing 100 and a wick 200. In Figure 2, the wick 200 is shown floating above the bottom surface 20, but in reality, it is in contact with the bottom surface 20.

[0041] As shown in Figure 2, the internal space of the housing 100 is divided by a top surface 10 and a bottom surface 20 facing each other in the thickness direction (indicated by arrow Z in Figure 2), a first side surface 30 and a second side surface 40 facing each other in a first direction perpendicular to the thickness direction Z (indicated by arrow Y in Figure 2), and a third side surface 50 and a fourth side surface 60 facing each other in a second direction perpendicular to the thickness direction Z and the first direction Y (indicated by arrow X in Figure 2). As shown in Figure 2, the bottom surface 20 has a first bottom surface 21 and a second bottom surface 22. The minimum distance between the first bottom surface 21 and the top surface 10 (indicated by double arrow TB in Figure 2) １ The distance shown by (also called the height from the first base 21 to the top surface 10) is the minimum distance between the second base 22 and the top surface 10 (in Figure 2, double arrow TB ２ This is the distance shown, and is smaller than the height from the second base surface 22 to the top surface 10. A step 23 is provided between the first base surface 21 and the second base surface 22.

[0042] The step 23 has a first step surface 23a, a second step surface 23b, and a first connecting step surface 23c that connects the end of the first step surface 23a and the end of the second step surface 23b.

[0043] Height TB from the first base 21 to the top surface 10 １ The height TB from the second base surface 22 to the top surface 10 ２Although not particularly limited if it is smaller (shorter) than, it is preferably 15 μm or more and 200 μm or less. The height TB from the second bottom surface 22 to the top surface 10 ２ is the height TB from the first bottom surface 21 to the top surface 10 １ Although not particularly limited if it is larger (longer) than, it is preferably 30 μm or more and 400 μm or less.

[0044] The wick 200 has a planar shape that coincides with the planar shape of the bottom surface 20 of the housing 100. In other words, the four corners of the wick 200 coincide with the four corners of the bottom surface 20 of the housing 100, respectively. Further, the wick 200 has a shape corresponding to the step 23 of the housing 100. Specifically, the wick 200 has a first bottom surface covering portion 121 that covers the first bottom surface 21, a second bottom surface covering portion 122 that covers the second bottom surface 22, a first step surface covering portion 123a that covers the first step surface 23a, and a second step surface covering portion 123b that covers the second step surface 23b. Therefore, it can be said that the wick 200 covers the bottom surface 20 of the housing 100. However, the wick 200 does not cover the first connection step surface 23c of the housing 100.

[0045] FIG. 3 is a top view of the housing shown in FIG. 2. In the top view of the housing shown in FIG. 3, in order to explain the shape of the internal space of the housing 100, it is a view through the top surface 10. The same applies to other top views of the housing.

[0046] As shown in FIG. 3, the internal space of the housing 100 has a length LB in the first direction Y １ and a length LB in the second direction X ２ and may be a substantially rectangular shape. The length LB of the internal space in the second direction X ２ is longer (larger) than the length LB in the first direction Y １ That is, it can be said that the internal space of the housing 100 has a substantially rectangular shape with a longitudinal direction in the second direction X.

[0047] The first step surface 23a and the second step surface 23b constituting the step 23 are parallel to the first direction Y, but the first connection step surface 23c connecting the end of the first step surface 23a and the end of the second step surface 23b in the first direction Y is not parallel to the first direction Y.

[0048] The step 23 has a crank shape consisting of a first step surface 23a extending a predetermined distance along the first direction Y from the first side surface 30 toward the second side surface 40, a first connecting step surface 23c extending a predetermined distance along the second direction X from the end of the first step surface 23a toward the third side surface 50, and a second step surface 23b extending from the end of the first connecting step surface 23c on the third side surface 50 side toward the second side surface 40 along the first direction Y. The length of the first step surface 23a in the first direction Y (in Figure 3, double arrow LB) ３ａ The length shown by ( ) and the length of the second stepped surface 23b (in Figure 3, double arrow LB ３ｂ The sum of the lengths shown is equal to the length LB of the base 20 in the first direction Y. １ This is equivalent to the first connecting step surface 23c being perpendicular to the first direction Y (and parallel to the second direction X).

[0049] Length of the first connecting step surface 23c in the second direction X (in Figure 3, double arrow LB) ３ｃ The length shown is equal to the length of the first base B portion 21B in the second direction X, and the length of the second base B portion 22B in the second direction X. The first base B portion and the second base B portion will be described later.

[0050] Furthermore, the bottom surface 20 is the first region A １ and the second region A ２ It has. First region A １ This consists of a part of the first bottom surface 21 and a part of the second bottom surface 22 that are continuous with the first stepped surface 23a in the second direction X. Second region A ２ This consists of a part of the first bottom surface 21 and a part of the second bottom surface 22 that are continuous with the second stepped surface 23b in the second direction X.

[0051] The first bottom surface 21 can be divided into two parts with respect to the second stepped surface 23b. That is, the first bottom surface 21 has a first bottom surface A portion 21A, which is the part on the third side surface 50 side of the second stepped surface 23b, and a first bottom surface B portion 21B, which is the part on the fourth side surface 60 side of the second stepped surface 23b. If the first direction Y is the width direction and the second direction X is the length direction, the width of the first bottom surface A portion 21A (double arrow LB)１ ) is the width of the first bottom surface B portion 21B (double arrow LB ３ａ It is wider than ).

[0052] The second bottom surface 22 can be divided into two parts with respect to the first stepped surface 23a. That is, the second bottom surface 22 has a second bottom surface A portion 22A, which is the part on the fourth side surface 60 side of the first stepped surface 23a, and a second bottom surface B portion 22B, which is the part on the third side surface 50 side of the first stepped surface 23a. The width of the second bottom surface A portion 22A (double arrow LB １ ) is the width of the second bottom surface B part 22B (double arrow LB ３ｂ It is wider than ).

[0053] Figure 4 is a diagram showing the first bottom surface A, first bottom surface B, second bottom surface A, and second bottom surface B of the housing shown in Figure 3, with different hatching. As shown in Figure 4, the first bottom surface A 21A is the first region A １ and second region A ２ It is positioned across both, but the first bottom surface B portion 21B is in the first region A １ It is arranged only in the first region A. １ and second region A ２ The first bottom surface A portion 21A is positioned across both sides, and the first region A １ It includes a first bottom surface B portion 21B which is positioned only on the bottom surface. There is no step between the first bottom surface A portion 21A and the first bottom surface B portion 21B.

[0054] Furthermore, the second bottom surface A portion 22A is the first region A １ and second region A ２ It is positioned across both, but the second bottom surface B portion 22B is in the second region A ２ It is arranged only in the first region A. １ and second region A ２ A second bottom surface A portion 22A is positioned across both sides, and the second region A ２ It includes a second bottom surface B portion 22B which is positioned only on the bottom surface. There is no step between the second bottom surface A portion 22A and the second bottom surface B portion 22B.

[0055] Figure 5 is a perspective view of the bottom surface of the housing shown in Figure 2, viewed from the outside. As shown in Figure 5, when the bottom surface of the housing is viewed from the outside, there is a step on the bottom surface. Also, the shape of the bottom surface 20 of the housing 100 when viewed from the outside of the housing 100 is substantially the same as the shape of the bottom surface 20 when viewed from the inside of the housing 100.

[0056] In the heat diffusion device of the present invention, the wick has a first part that continuously covers the first bottom surface, the first stepped surface, and the second bottom surface of the housing along a second direction, and a second part that continuously covers the first bottom surface, the first stepped surface, and the second bottom surface of the housing along a second direction. This will be explained with reference to Figures 6 and 7.

[0057] Figure 6 is a cross-sectional view taken along the line VI-VI of the thermal diffusion device shown in Figure 1. The cross-sectional view in Figure 6 shows the first region A of the housing 100 that constitutes the thermal diffusion device shown in Figure 1. １ (See Figure 3) This is a cross-sectional view obtained by cutting along the second direction X, showing the positional relationship between the first part of the wick and the bottom surface covered by the first part. As shown in Figure 6, the wick 200 continuously covers the first bottom surface 21 (first bottom surface A part 21A and first bottom surface B part 21B), the first stepped surface 23a, and the second bottom surface 22 (second bottom surface A part 22A) of the housing 100 along the second direction X. The part of the wick 200 that continuously covers the first bottom surface 21, the first stepped surface 23a, and the second bottom surface 22 along the second direction X is also called the first part 200A.

[0058] The portion of the bottom surface 20 covered by the first part 200A of the wick 200 is the first region A as explained in Figures 3 and 4. １ Therefore, if the first part 200A of the wick 200 continuously covers the first bottom surface 21 (first bottom surface A part 21A and first bottom surface B part 21B), the first stepped surface 23a, and the second bottom surface 22 (second bottom surface A part 22A) along the second direction X, then the first region A １ In this configuration, the movement of the working medium in the second direction X across the step 23 is not hindered. Therefore, even when the step 23 is present, there is no decrease in the maximum heat transport characteristics.

[0059] In Figure 6, the first part 200A of the wick 200 is provided up to a position where it contacts the third side surface 50 and the fourth side surface 60 of the housing 100. However, the first part 200A of the wick 200 does not need to be in contact with the third side surface 50 and the fourth side surface 60 of the housing 100, as long as it continuously covers the first bottom surface 21, the first stepped surface 23a, and the second bottom surface 22 along the second direction X.

[0060] Distance TB from the top surface 10 to the first bottom surface 21 in the thickness direction Z １ This is the distance TB from the top surface 10 to the second bottom surface 22 in the thickness direction Z. ２ Smaller than the distance TB from the top surface 10 to the second bottom surface 22 in the thickness direction Z. ２ This is the distance TB from the top surface 10 to the first bottom surface 21 in the thickness direction Z. １ And the length TB of the first stepped surface 23a in the thickness direction Z ３ａ It is equal to the sum of the (heights).

[0061] Figure 7 is a cross-sectional view taken along line VII-VII of the thermal diffusion device shown in Figure 1. The cross-sectional view in Figure 7 shows the second region A of the housing 100 that constitutes the thermal diffusion device shown in Figure 1. ２ (See Figure 3) This is a cross-sectional view obtained by cutting along the second direction X, showing the positional relationship between the second part of the wick and the housing. As shown in Figure 7, the wick 200 continuously covers the first bottom surface 21 (first bottom surface A part 21A), the second stepped surface 23b, and the second bottom surface 22 (second bottom surface B part 22B and second bottom surface A part 22A) of the housing 100 along the second direction X. The part of the wick 200 that continuously covers the first bottom surface 21, the second stepped surface 23b, and the second bottom surface 22 along the second direction X is also called the second part 200B.

[0062] Of the bottom surface 20, the portion covered by the second part 200B of the wick 200 is the second region A as explained in Figures 3 and 4. ２ Therefore, if the second part 200B of the wick 200 continuously covers the first bottom surface 21 (first bottom surface A part 21A), the second stepped surface 23b, and the second bottom surface 22 (second bottom surface B part 22B and second bottom surface A part 22A) along the second direction X, then the second region A ２In this configuration, the movement of the working medium in the second direction X across the step 23 is not hindered. Therefore, even when the step 23 is present, there is no decrease in the maximum heat transport characteristics.

[0063] In Figure 7, the second part 200B of the wick 200 is provided up to a position where it contacts the third side surface 50 and the fourth side surface 60 of the housing 100. However, the second part 200B of the wick 200 does not need to be in contact with the third side surface 50 and the fourth side surface 60 of the housing 100, as long as it continuously covers the first bottom surface 21, the second stepped surface 23b, and the second bottom surface 22 along the second direction X.

[0064] Preferably, the wick is bonded to the first bottom surface, second bottom surface, first stepped surface, and second stepped surface of the housing by diffusion bonding. When the wick is diffusely bonded to the first bottom surface, second bottom surface, first stepped surface, and second stepped surface of the housing, the wick is fixed to the first bottom surface, second bottom surface, first stepped surface, and second stepped surface of the housing, thus preventing a decrease in the transport efficiency of the working medium due to a gap forming between the wick and the housing.

[0065] The wick is preferably made of a sheet-like wick. For example, the wick is made of a single sheet-like wick having a substantially rectangular portion having first and second sides facing a first direction and third and fourth sides facing a second direction, and having a slit provided in the substantially rectangular portion along the second direction, and it is preferable that the rectangular portion of the sheet-like wick is placed on the bottom surface of the housing.

[0066] Figure 8 is a schematic perspective view showing a sheet-like wick that constitutes the heat diffusion device shown in Figure 1. The sheet-like wick shown in Figure 8 is also the sheet-like wick shown in Figure 2 before bending. The sheet-like wick 210 shown in Figure 8 has a substantially rectangular portion 120 having a first side surface 120a and a second side surface 120b facing a first direction Y, and a third side surface 120c and a fourth side surface 120d facing a second direction X. The substantially rectangular portion 120 also has a slit 125, which is a discontinuous portion provided along the second direction X when the sheet-like wick is bent and placed on the bottom surface of the housing.

[0067] The length of the roughly rectangular portion 120 shown in Figure 8 in the first direction Y (in Figure 8, double arrow LS) １ The length shown is the length LB in the first direction Y of the bottom surface 20 of the housing 100 shown in Figure 3. １ It is the same as the length of the roughly rectangular portion 120 shown in Figure 8 in the second direction X (in Figure 8, the double arrow LS) ２ The length shown is the length LB in the second direction X of the bottom surface 20 of the housing 100 shown in Figure 3. ２ The length of the first stepped surface 23a or the second stepped surface 23b in the thickness direction Z shown in Figure 7 (TB ３ａ Or TB ３ｂ It is the same as the length when the length of the roughly rectangular portion 120 in the second direction X is added. ２ This is the length LB of the bottom surface 20 of the housing 100 in the second direction X. ２ It is longer than that.

[0068] Of the roughly rectangular portion 120, the portion that covers the first bottom surface A portion 21A of the housing 100 when positioned on the bottom surface 20 of the housing 100 is also called the first bottom surface A covering portion 121a. Similarly, the portion that covers the first bottom surface B portion 21B of the housing 100 is also called the first bottom surface B covering portion 121b. The first bottom surface A covering portion 121a and the first bottom surface B covering portion 121b are collectively called the first bottom surface covering portion 121. The first bottom surface covering portion 121 has a first side surface 120a, a third side surface 120c, a second side surface 120b, and a first fold line F ２１ , slit 125, and third bending line F ２３ It is also a section demarcated by [the relevant factor].

[0069] Of the roughly rectangular portion 120, the portion that covers the second bottom surface A portion 22A of the housing 100 when positioned on the bottom surface 20 of the housing 100 is also called the second bottom surface A covering portion 122a. Similarly, the portion that covers the second bottom surface B portion 22B of the housing 100 is also called the second bottom surface B covering portion 122b. The second bottom surface A covering portion 122a and the second bottom surface B covering portion 122b together are also called the second bottom covering portion 122. The second bottom covering portion 122 has a first side surface 120a, a fourth side surface 120d, a second side surface 120b, and a second fold line F ２２ , slit 125 and fourth bending line F ２４This is the part demarcated by [the specified element].

[0070] In Figure 8, the first bottom surface A covering portion 121a is shown with the same hatching as the first bottom surface A portion 21A of the housing 100 shown in Figure 4. Similarly, the first bottom surface B covering portion 121b is shown with the same hatching as the first bottom surface B portion 21B, the second bottom surface A covering portion 122a is shown with the same hatching as the second bottom surface A portion 22A, and the second bottom surface B covering portion 122b is shown with the same hatching as the second bottom surface B portion 22B.

[0071] A slit 125 is provided in the roughly rectangular portion 120. The slit 125 is for deforming the roughly rectangular portion 120 and positioning it on the bottom surface 20 of the housing 100, but the length LS of the slit 125 in the second direction X ５ The length LB of the first connecting step surface 23c in the second direction X is ３ｃ (See Figure 3) The length of the slit 125 does not match LS ５ The length LB of the first connecting step surface 23c ３ｃ It is longer than that.

[0072] The position where the slit 125 is provided is the third side slit end P. １ and the fourth side slit end P ４ It is determined by [the following].

[0073] Third side slit end P １ This is the point where the sheet-like wick 210 overlaps the third side connection end, which is the point on the first connection step surface 23c closest to the third side 120c, when the third side 120c of the roughly rectangular portion 120 is aligned with the third side 50 of the housing 100. On the other hand, the fourth side slit end P ４ This is the point where the sheet-like wick 210 overlaps the fourth side connection end, which is the point on the first connection step surface 23c closest to the fourth side 120d, when the fourth side 120d of the roughly rectangular portion 120 is aligned with the fourth side 60 of the housing 100.

[0074] Length of the slit 125 in the second direction X (in Figure 8, double arrow LS) ５The length shown is equal to the sum of the length of the first bottom surface B covering portion 121b in the second direction X and the length of the first stepped surface covering portion 123a in the second direction X. Also, the length of the slit 125 in the second direction X is LS ５ This is equal to the sum of the length of the second bottom surface B covering portion 122b in the second direction X and the length of the second stepped surface covering portion 123b in the second direction X.

[0075] However, the length of the slit 125 LS ５ This is the third side slit end P in the second direction X. １ From the fourth side slit end P ４ It may be longer than the length up to LS. Length of slit 125 LS ５ The third side slit end P in the second direction X １ From the fourth side slit end P ４ If the length is exactly equal to the length up to the first fold line F, which will be described later, ２１ , second folding line F ２２ , third folding line F ２３ , fourth folding line F ２４ When folding the sheet-like wick, the length of the slit may be insufficient by the length of the radius corresponding to the thickness of the sheet-like wick. Length of slit 125 LS ５ The third side slit end P in the second direction X １ From the fourth side slit end P ４ Making it longer than the length up to can prevent the aforementioned slit length from being insufficient. In this case, the slit 125 is the third side slit end P １ It extends further toward the third side surface 120c, and the slit end P on the fourth side surface ４ It is preferable that it extends further toward the fourth side surface 120d. However, even if the slit extends as described above, the slit end P on the third side surface １ and the fourth side slit end P ４ Its position remains unchanged.

[0076] The roughly rectangular portion 120 has a first fold line F ２１ , second folding line F ２２, the third folding line F ２３ , the fourth folding line F ２４ is provided, and bending processing is performed based on the folding line. The first folding line F ２１ is provided at a position connecting the third side surface side slit end P １ and the second side surface 120b at the shortest distance. The second folding line F ２２ is provided at a position connecting the third side surface side slit end P １ and the second side surface 120b at the shortest distance at a point that has moved along the second direction X from the third side surface side slit end P ２ by the length of the second stepped surface 23b in the thickness direction Z to the fourth side surface 120d side. The fourth folding line F ２４ is provided at a position connecting the fourth side surface side slit end P ４ and the first side surface 120a at the shortest distance. The third folding line F ２３ is provided at a position connecting the fourth side surface side slit end P ４ and the first side surface 120a at the shortest distance at a point that has moved along the second direction X from the fourth side surface side slit end P ３ by the length of the first stepped surface 23a in the thickness direction to the third side surface 120c side.

[0077] For the first folding line F ２１ , the sheet-like wick 210 is folded into a mountain fold. For the second folding line F ２２ , the sheet-like wick 210 is folded into a valley fold. For the third folding line F ２３ , the sheet-like wick 210 is folded into a mountain fold. For the fourth folding line F ２４ , the sheet-like wick 210 is folded into a valley fold. By folding as described above, the sheet-like wick 210 is three-dimensionally deformed as shown in FIG. 9.

[0078] Note that mountain folds and valley folds are defined based on the sheet-like wick before folding, and assuming that the covering portion of the first bottom surface A of the roughly rectangular portion of the sheet-like wick is aligned with the first bottom surface A of the housing. Folding so that it is convex toward the opposite side of the housing is called a "mountain fold," and folding so that it is convex toward the housing is called a "valley fold." Therefore, if the sheet-like wick is turned inside out or other parts are folded, the front and back sides will be reversed, and the mountain folds and valley folds will be the opposite of those shown in the diagram.

[0079] Figure 9 is a perspective view showing the sheet-like wick shown in Figure 8 after it has been bent. The sheet-like wick shown in Figure 9 is placed on the bottom surface 20 of the housing 100 shown in Figure 2 to form the wick 200 shown in Figure 2. Due to the bending process, the first stepped surface covering portion 123a and the second stepped surface covering portion 123b of the sheet-like wick 210 become parallel to the thickness direction Z, and the third side slit end P in the second direction X １ The position and the third side slit bend portion P ２ The positions of the four sides overlap. Similarly, the fourth side slit end P in the second direction X. ４ The position and the fourth side slit bend portion P ３ The positions of the sheet wick and the housing 100 overlap. As a result, the length of the sheet wick 210 in the second direction X matches the length of the bottom surface 20 of the housing 100 in the second direction X, so the shape of the sheet wick 210 corresponds to the shape of the bottom surface 20 of the housing 100. Therefore, when placing the sheet wick 210 shown in Figure 9 on the bottom surface 20 of the housing 100 shown in Figures 3 and 4, no wrinkles or tears will occur in the sheet wick 210.

[0080] The first stepped surface covering portion 123a is a sheet-like wick 210 shown in Figure 8, and in the second direction X, the third fold line F ２３ and the fourth fold line F ２４This is the region sandwiched between the first bottom surface B covering portion 121b and the second bottom surface A covering portion 122a, and is perpendicular to the first bottom surface B covering portion 121b and the second bottom surface A covering portion 122a when bent. Therefore, by arranging the sheet-like wick 210 on the bottom surface 20 of the housing 100 such that the first bottom surface B covering portion 121b and the second bottom surface A covering portion 122a cover the first bottom surface B portion 21B and the second bottom surface A portion 22A respectively, the first stepped surface 23a is covered by the first stepped surface covering portion 123a. Therefore, the third bending line F ２３ and the fourth fold line F ２４ By placing a sheet-like wick 210, which has been bent to match the position of the first stepped surface 23a, inside the housing, the first region A １ In this configuration, the first bottom surface B portion 21B of the first bottom surface 21, the first stepped surface 23a, and the second bottom surface A portion 22A of the second bottom surface 22 can be continuously covered along the second direction X by the first bottom surface B covering portion 121b, the first stepped surface covering portion 123a, and the second bottom surface A covering portion 122a of the sheet-like wick 210.

[0081] The second stepped surface covering portion 123b is formed in the sheet-like wick 210 shown in Figure 8, along the first fold line F in the second direction X. ２１ and the second fold line F ２２ This is the region sandwiched between the first bottom surface A covering portion 121a and the second bottom surface B covering portion 122b, and while being bent, it is perpendicular to the first bottom surface A covering portion 121a and the second bottom surface B covering portion 122b. Therefore, by arranging the sheet-like wick 210 on the bottom surface 20 of the housing 100 such that the first bottom surface A covering portion 121a and the second bottom surface B covering portion 122b cover the first bottom surface A portion 21A and the second bottom surface B portion 22B respectively, the second stepped surface 23b is covered by the second stepped surface covering portion 123b. Therefore, the first bending line F ２１ and the second fold line F ２２ By placing a sheet-like wick 210, which has been bent to match the position of the second stepped surface 23b, inside the housing 100, the second region A ２Within the structure, the first bottom surface A portion 21A of the first bottom surface 21, the second stepped surface 23b, and the second bottom surface B portion 22B of the second bottom surface 22 can be continuously covered along the second direction X by the first bottom surface A covering portion 121a, the second stepped surface covering portion 123b, and the second bottom surface B covering portion 122b of the sheet-like wick 210.

[0082] In other words, by placing the folded sheet-like wick 210 on the bottom surface 20 of the housing 100, the first bottom surface 21 can be covered by the first bottom surface covering portion 121, the second bottom surface 22 by the second bottom surface covering portion 122, the first stepped surface covering portion 123a can cover the first stepped surface 23a, and the second stepped surface covering portion 123b can cover the second stepped surface 23b.

[0083] The first part 210A is the portion of the sheet-like wick 210 that continuously covers the first bottom surface 21, the first stepped surface 23a, and the second bottom surface 22 in the second direction X. The first part 210A consists of a part of the first bottom surface A covering portion 121a, the first bottom surface B covering portion 121b, the first stepped surface covering portion 123a, and a part of the second bottom surface A covering portion 122a.

[0084] The second part 210B is the portion of the sheet-like wick 210 that continuously covers the first bottom surface 21, the second stepped surface 23b, and the second bottom surface 22 in the second direction X. The second part 210B consists of a part of the first bottom surface A covering portion 121a, the second stepped surface covering portion 123b, the second bottom surface B covering portion 122b, and a part of the second bottom surface A covering portion 122a.

[0085] Furthermore, in the method described above, where the sheet-like wick 210 is bent and placed on the bottom surface of the housing 100, the first connecting stepped surface 23c of the housing 100 cannot be covered with the wick. In other words, between the first bottom surface B covering portion 121b of the first part 210A of the wick 200 and the second bottom surface B covering portion 122b of the second part 210B of the wick 200, there is a discontinuous portion where the wick 200 is not continuous in the first direction Y along the first connecting stepped surface 23c.

[0086] In Figure 9, the third side slit end P １ , third side slit bent portion P ２ , fourth side slit end P４ , fourth side slit bent portion P ３ The rectangular area enclosed by the rectangle corresponds to the first connecting step surface 23c of the housing 100, and this area is a discontinuous portion where the sheet-like wick does not exist.

[0087] Methods for covering the first connecting step surface 23c with a wick include preparing another sheet-like wick (second sheet-like wick) to cover the first connecting step surface 23c, stacking it with the sheet-like wick and placing it in the housing, or providing a folding portion in the sheet-like wick and covering the first connecting step surface 23c by folding the folding portion.

[0088] The following describes a method using the second sheet-type wick. Note that when the second sheet-type wick is used, the original sheet-type wick will also be referred to as the first sheet-type wick to distinguish it from the second sheet-type wick.

[0089] Figure 10 is a schematic perspective view showing an example of a second sheet-like wick. The second sheet-like wick 220 shown in Figure 10 has a first bottom surface A covering portion 221a, a first bottom surface B covering portion 221b, a first stepped surface covering portion 223a, a second bottom surface A covering portion 222a, a first connecting stepped surface covering portion 223c, and a second bottom surface B covering portion 222b.

[0090] The second sheet-like wick 220 has a shape that is a modified rectangular shape and has a first side surface 220a and a second side surface 220b facing the first direction Y, and a third side surface 220c and a fourth side surface 220d facing the second direction X.

[0091] The first bottom surface A covering portion 221a is a portion that covers the first bottom surface A portion 21A of the housing 100 shown in Figure 2, and is substantially the same shape as the first bottom surface A portion 21A. Therefore, the first bottom surface A covering portion 221a is shown with the same hatching as the first bottom surface A portion 21A.

[0092] The first bottom surface B covering portion 221b is a portion that covers the first bottom surface B portion 21B of the housing 100 shown in Figure 2, and is substantially the same shape as the first bottom surface B portion 21B. Therefore, the first bottom surface B covering portion 221b is shown with the same hatching as the first bottom surface B portion 21B. The first bottom surface B covering portion 221b is provided on the fourth side surface 220d side of the first bottom surface A covering portion 221a, and is continuous with the first bottom surface A covering portion 221a.

[0093] The first stepped surface covering portion 223a is a portion that covers the first stepped surface 23a of the housing 100 shown in Figure 2 and has substantially the same shape as the first stepped surface 23a. Therefore, the first stepped surface covering portion 223a is shown with the same hatching as the first stepped surface covering portion 123a of the sheet-like wick 210 shown in Figures 8 and 9. The first stepped surface covering portion 223a is provided on the fourth side surface 220d side of the first bottom surface B covering portion 221b, and is continuous with the first bottom surface B covering portion 221b.

[0094] The second bottom surface A covering portion 222a is a portion that covers the second bottom surface A portion 22A of the housing 100 shown in Figure 2, and is substantially the same shape as the second bottom surface A portion 22A. Therefore, the second bottom surface A covering portion 222a is shown with the same hatching as the second bottom surface A portion 22A. The second bottom surface A covering portion 222a is provided on the fourth side surface 220d side of the first stepped surface covering portion 223a, and is continuous with the first stepped surface covering portion 223a.

[0095] The first connecting step surface covering portion 223c is a portion that covers the first connecting step surface 23c of the housing 100 shown in Figure 2, and is substantially the same shape as the first connecting step surface 23c. The first connecting step surface covering portion 223c is provided on the second side surface 220b side of the first bottom surface B covering portion 221b, and is continuous with the first bottom surface B covering portion 221b. Note that the first connecting step surface covering portion 223c is not continuous with the first bottom surface A covering portion 221a.

[0096] The second bottom surface B covering portion 222b is a portion that covers the second bottom surface B portion 22B of the housing 100 shown in Figure 2, and is substantially the same shape as the second bottom surface B portion 22B. Therefore, the second bottom surface B covering portion 222b is shown with the same hatching as the second bottom surface B portion 22B. The second bottom surface B covering portion 222b is provided on the second side surface 220b side of the first connecting step surface covering portion 223c, and is continuous with the first connecting step surface covering portion 223c. Note that the second bottom surface B covering portion 222b is not continuous with the first bottom surface A covering portion 221a.

[0097] The length of the second sheet-like wick 220 in the second direction X is the sum of the lengths of the first bottom surface A covering portion 221a, the first bottom surface B covering portion 221b, the first stepped surface covering portion 223a, and the second bottom surface A covering portion 222a in the second direction X (in Figure 10, double arrow LS) ４ The length is represented by the length shown by LS. The length of the second sheet-like wick 220 in the second direction X is LS. ４ This is the length LB of the bottom surface 20 of the housing 100 in the second direction X. ２ It is longer than that.

[0098] On the other hand, the sum of the lengths of the first bottom surface A covering portion 221a, the first bottom surface B covering portion 221b, and the second bottom surface A covering portion 222a in the second direction X is equal to the length LB of the bottom surface 20 of the housing 100 in the second direction X. ２ This is equal to the length LS of the second sheet-like wick 220 in the second direction X. ４ This is the length LB of the bottom surface 20 of the housing 100 in the second direction X, equal to the length of the first stepped surface covering portion 223a in the second direction X. ２ It is longer than that.

[0099] The length of the first bottom surface A covering portion 221a and the length of the second bottom surface A covering portion 222a in the first direction Y (in Figure 10, double arrow LS) ３ The length shown is the length LB of the bottom surface 20 of the housing 100 in the first direction Y. １ It is equal to . Also, the sum of the lengths of the first bottom surface B covering portion 221b and the second bottom surface B covering portion 222b in the first direction Y is equal to the length of the first bottom surface A covering portion 221a in the first direction Y, or the length LS of the second bottom surface A covering portion 222a in the first direction Y. ３This is equal to the length LB of the bottom surface 20 of the housing 100 in the first direction Y. In other words, the maximum length of the second sheet-like wick 220 in the first direction Y (the length at the point where the first bottom surface B covering portion 221b, the first connecting step surface covering portion 223c, and the second bottom surface B covering portion 222b are aligned in the first direction Y) is equal to the length of the first connecting step surface covering portion 223c in the first direction Y. １ It is longer than that.

[0100] The second sheet-like wick 220 has a boundary line F between the first bottom surface B covering portion 221b and the first stepped surface covering portion 223a. ４１ Fold it in a mountain fold, and the boundary line F between the first stepped surface covering portion 223a and the second bottom surface A covering portion 222a ４２ Fold it in the valley and the boundary line F between the first bottom surface B covering portion 221b and the first connecting step surface covering portion 223c ４３ Fold it in a mountain fold, and the boundary line F between the first connecting step surface covering portion 223c and the second bottom surface B covering portion 222b ４４ By folding it inwards, it is deformed as shown in Figure 11.

[0101] Furthermore, boundary line F is located on the fourth side surface 220d side of the first bottom surface A covering portion 221a and forms the boundary between it and the first bottom surface B covering portion 221b, the first connecting step surface covering portion 223c, and the second bottom surface B covering portion 222b. ４０ Although it cannot be folded, slits are provided between the first bottom surface A covering portion 221a and the first connecting step surface covering portion 223c, and between the first bottom surface A covering portion 221a and the second bottom surface B covering portion 222b, and these slits are not continuous in the second direction X.

[0102] Figure 11 is a perspective view showing the second sheet-like wick shown in Figure 10 after it has been folded.

[0103] Boundary line F ４１ Fold it in half, along boundary line F ４２ By folding it in the valley direction, the length of the second sheet-like wick 220 in the second direction X after bending is equal to the length LB of the bottom surface 20 of the housing 100 in the second direction X. ２ It matches boundary line F. ４３ Fold it in half, along boundary line F ４４By folding it in the valley direction, the length of the second sheet-like wick 220 in the first direction Y after bending is equal to the length LB of the bottom surface 20 of the housing 100 in the first direction Y. １ This coincides with the first connection step surface covering portion 223c, which is parallel to the thickness direction Z and can cover the first connection step surface 23c of the housing 100.

[0104] Therefore, by stacking the second sheet-like wick 220 shown in Figure 11 with, for example, the sheet-like wick (first sheet-like wick) 210 shown in Figure 9 and placing it on the bottom surface 20 of the housing 100, the second sheet-like wick 220 can continuously cover the first bottom surface B portion 21B of the first bottom surface 21, the first connecting step surface 23c, and the second bottom surface B portion 22B of the second bottom surface 22 along the first direction Y. With the above configuration, the movement of the working medium between the first bottom surface 21 (first bottom surface B portion 21B) and the second bottom surface 22 (second bottom surface B portion 22B) across the first connecting step surface 23c in the first direction Y is not hindered, and therefore, a decrease in the maximum heat transport characteristics does not occur even in the first direction Y.

[0105] The second sheet-like wick 220 has a first portion 220A that continuously covers the first bottom surface 21, the first stepped surface 23a, and the second bottom surface 22 of the housing 100 along the second direction X, but does not have a second portion that continuously covers the first bottom surface 21, the second stepped surface 23b, and the second bottom surface 22 of the housing 100 along the second direction X.

[0106] The sheet-like wick may have a folded portion that is continuous with the substantially rectangular portion, in addition to the substantially rectangular portion. In this case, it is preferable that a part of the folded portion that is folded toward the substantially rectangular portion covers the first connecting step surface of the housing.

[0107] An example of a sheet-like wick with a foldable portion will be described with reference to Figures 12 and 13. Figure 12 is a schematic perspective view showing another example of a sheet-like wick.

[0108] The sheet-like wick 211 shown in Figure 12 has a folding portion 130 in addition to a roughly rectangular portion 120. The configuration of the roughly rectangular portion 120 is the same as that of the roughly rectangular portion 120 described in Figure 8.

[0109] The folding portion 130 has a first portion 130a that is continuous with the second side surface 120b of the second bottom surface B covering portion 122b of the substantially rectangular portion 120 and covers the second bottom surface B portion 22B of the housing 100 when folded; a second portion 130b that is continuous with the first portion 130a on the side opposite to the second side surface 120b and covers the first connecting stepped surface 23c of the housing 100 when folded; and a third portion 130c that is continuous with the second portion 130b on the side opposite to the second side surface 120b and covers the first bottom surface B portion 21B when folded.

[0110] The first portion 130a and the third portion 130c are given the same hatching as the second bottom surface B portion 22B and the first bottom surface B portion 21B, respectively. The second portion 130b is given the same hatching as the first connection step surface covering portion 223c of the sheet-like wick 210 shown in Figures 10 and 11, which covers the same area of ​​the housing.

[0111] Figure 13 is a perspective view showing the sheet-like wick shown in Figure 12 after it has been folded. Regarding the sheet-like wick 211 shown in Figure 12, after folding the roughly rectangular portion 120 in the same manner as in Figure 9, the boundary line F between the first portion 130a and the second portion 130b ３１ Fold in the mountain fold, and the boundary line F between the second part 130b and the third part 130c ３２ The sheet-like wick 211 shown in Figure 13 is formed by folding it in the valley. From the state shown in Figure 13, the boundary line F between the roughly rectangular portion 120 and the first portion 130a ３０ In this configuration, the sheet-like wick 211 is folded 180° in a valley fold so that the first portion 130a overlaps the second bottom surface B covering portion 122b of the substantially rectangular portion 120, thereby allowing the third portion 130c to cover the first bottom surface B covering portion 121b of the substantially rectangular portion 120, and the second portion 130b to cover the first connecting stepped surface 23c of the housing 100.

[0112] Figure 14 is a schematic perspective view showing yet another example of a sheet-like wick. The sheet-like wick 212 shown in Figure 14 is a form in which the sheet-like wick 211, which has a folding portion 130 as shown in Figures 12 and 13, further has a second substantially rectangular portion 120'. Therefore, the positions in which the substantially rectangular portion 120 and the folding portion 130 are arranged on the bottom surface 20 of the housing 100 are the same as those of the sheet-like wick 211.

[0113] If the folding portion 130 and the second roughly rectangular portion 120' are collectively referred to as the folding portion 140, then the sheet-like wick 212 can also be described as having a shape in which the folding portion 140 is connected to the roughly rectangular portion 120.

[0114] The sheet-like wick 212 has a second substantially rectangular portion 120' which is the same shape as the substantially rectangular portion 120 and is provided continuously with the third portion 130c of the folding portion 130c on the side opposite to the second side surface 120b of the substantially rectangular portion 120, covering the first bottom surface A portion 21A, the first bottom surface B portion 21B, the second bottom surface A portion 22A, the second bottom surface B portion 22B, the first stepped surface 23a, and the second stepped surface 23b of the housing 100 when folded.

[0115] The roughly rectangular portion 120 is the same as the roughly rectangular portion 120 described in Figures 8 and 9. Therefore, by folding the roughly rectangular portion 120 as shown in Figure 9, the first region A １ In this configuration, the first bottom surface B portion 21B of the first bottom surface 21, the first stepped surface 23a, and the second bottom surface A portion 22A of the second bottom surface 22 are continuously covered along the second direction X by the first bottom surface B covering portion 121b, the first stepped surface covering portion 123a, and the second bottom surface A covering portion 122a, forming the second region A ２ Within the structure, the first bottom surface A portion 21A of the first bottom surface 21, the second stepped surface 23b, and the second bottom surface B portion 22B of the second bottom surface 22 can be continuously covered along the second direction X by the first bottom surface A covering portion 121a, the second stepped surface covering portion 123b, and the second bottom surface B covering portion 122b.

[0116] The folding portion 130 is the same as the folding portion 130 described in Figures 12 and 13. Therefore, the first portion 130a, the second portion 130b, and the third portion 130c of the folding portion 130 cover the second bottom surface B portion 22B, the first connecting step surface 23c, and the first bottom surface B portion 21B of the housing 100, respectively.

[0117] The second roughly rectangular portion 120' is substantially identical to the roughly rectangular portion 120 described in Figures 8 and 9, but its reference numeral and name have been changed to distinguish it from the roughly rectangular portion 120.

[0118] That is, the second substantially rectangular portion 120' has a first side surface 120'a and a second side surface 120'b facing the first direction Y, and a third side surface 120'c and a fourth side surface 120'd facing the second direction X, and has a first bottom surface A covering portion 121'a, a first bottom surface B covering portion 121'b, a second bottom surface A covering portion 122'a, a second bottom surface B covering portion 122'b, a first stepped surface covering portion 123'a, and a second stepped surface covering portion 123'b.

[0119] Furthermore, a slit 125' is provided in the second substantially rectangular portion 120'. The length of the slit 125' in the second direction X is equal to the length LB of the first connecting step surface 23c in the second direction X. ３ｃ It is longer than that.

[0120] The position where the slit 125' is provided is the third side slit end P. １ and the fourth side slit end P ４ Determined by the third side slit end P. １ This is the point where the sheet-like wick 212 overlaps the third side connection end, which is the point on the third side connection end of the first connection step surface 23c that is closest to the third side connection end 120'c, when the third side surface 120'c of the second roughly rectangular portion 120' is aligned with the third side surface 50 of the housing 100. Fourth side slit end P ４ This is the point where the sheet-like wick 212 overlaps the fourth side connection end, which is the point on the fourth side of the first connection step surface 23c closest to the fourth side 120'd, when the fourth side 120'd of the second roughly rectangular portion 120' is aligned with the fourth side 60 of the housing 100.

[0121] Furthermore, the second roughly rectangular portion 120' has a first fold line F ２１ , second folding line F ２２ , third folding line F ２３ , fourth folding line F ２４ A system is in place.

[0122] Therefore, the second roughly rectangular portion 120' is folded along the first fold line F in the same way as the roughly rectangular portion 120. ２１ Fold it in a mountain fold, and fold it along the second fold line F ２２ Fold it inwards along the third fold line F ２３ Fold it in a mountain fold, along the fourth fold line F ２４ By folding it in a valley fold, the second substantially rectangular portion 120' can cover the first bottom surface A portion 21A, the first bottom surface B portion 21B, the second bottom surface A portion 22A, the second bottom surface B portion 22B, the first stepped surface 23a, and the second stepped surface 23b of the housing 100, respectively, with the first bottom surface A covering portion 121'a, the first bottom surface B covering portion 121'b, the second bottom surface A covering portion 122'a, the second bottom surface B covering portion 122'b, the first stepped surface covering portion 123'a, and the second stepped surface covering portion 123'b.

[0123] Another example of a sheet-like wick with a folding portion will be described with reference to Figure 15.

[0124] Figure 15 is a schematic perspective view showing yet another example of a sheet-like wick. The sheet-like wick 213 consists of a substantially rectangular portion 120 and a folding portion 220. The substantially rectangular portion 120 is the same as the substantially rectangular portion shown in Figure 8. The folding portion 220 is equivalent to the second sheet-like wick 220 shown in Figure 10 rotated 180° around the second direction X.

[0125] In other words, the folding portion 220 includes a first bottom surface A covering portion 221a having substantially the same shape as the first bottom surface A portion 21A of the housing 100, a first bottom surface B covering portion 221b having substantially the same shape as the first bottom surface B portion 21B of the housing 100 and provided continuously with the first bottom surface A covering portion 221a on the fourth side surface 220d side of the first bottom surface A covering portion 221a, a first stepped surface covering portion 223a having substantially the same shape as the first stepped surface 23a and provided continuously with the first bottom surface B covering portion 221b on the fourth side surface 220d side of the first stepped surface covering portion 223 It has a second bottom surface A covering portion 222a which is provided in a continuous manner and has substantially the same shape as the second bottom surface A portion 22A, a first connecting step surface covering portion 223c which is provided in a continuous manner from the first bottom surface B covering portion 221b on the substantially rectangular portion 120 side of the first bottom surface B covering portion 221b and has substantially the same shape as the first connecting step surface 23c, and a second bottom surface B covering portion 222b which is provided in a continuous manner from the first connecting step surface covering portion 223c on the substantially rectangular portion 120 side of the first connecting step surface covering portion 223c and is connected to the second bottom surface B covering portion 122b of the substantially rectangular portion 120.

[0126] After folding the folding portion 220 in the same manner as the second sheet-like wick 220 shown in Figure 10, the boundary F between the second bottom surface B covering portion 122b of the roughly rectangular portion 120 and the second bottom surface B covering portion 222b of the folding portion 220 ４５ Using this as a boundary, the folding portion 220 is folded (180° valley fold) toward the roughly rectangular portion 120, so that the first bottom surface A portion 21A, the first bottom surface B portion 21B, the first stepped surface 23a, the second bottom surface A portion 22A, the first connecting stepped surface 23c, and the second bottom surface B portion 22B of the housing 100 are covered by the first bottom surface A covering portion 221a, the first bottom surface B covering portion 221b, the first stepped surface covering portion 223a, the second bottom surface A covering portion 222a, the first connecting stepped surface covering portion 223c, and the second bottom surface B covering portion 222b of the folding portion 220.

[0127] Furthermore, the sheet-like wick 213 shown in Figure 15 corresponds to the second sheet-like wick 220 shown in Figure 10, which has been rotated 180° around the second direction X as an axis, and the portion corresponding to the second bottom surface B covering portion 222b has been connected to the second bottom surface B covering portion 122b of the substantially rectangular portion 120 shown in Figures 8 and 9.

[0128] The first connecting step surface may be parallel to the second direction, or it may be inclined by a predetermined angle from the second direction. Preferably, the inclination angle of the first connecting step surface from the second direction is 0° or more and 5° or less.

[0129] Figure 16 is a top view showing another example of the enclosure.

[0130] In the housing 101 shown in Figure 16, the end of the first stepped surface 24a on the second side surface 40 and the end of the second stepped surface 24b on the first side surface 30 are connected by a first connecting stepped surface 24c. The end of the first stepped surface 24a on the second side surface 40 and the end of the second stepped surface 24b on the first side surface 30 are not in the same position in the first direction Y. Therefore, the first connecting stepped surface 24c that connects these two ends can be said to be inclined with respect to the second direction X.

[0131] In a sheet-like wick 210 having a substantially rectangular portion 120 with a slit 125 parallel to the second direction X, as shown in Figure 8, it is not possible to continuously cover the first bottom surface 21, the second bottom surface 22, the first stepped surface 24a, and the second stepped surface 24b of the housing 101 shown in Figure 16. This is because, when the first connecting stepped surface 24c is not parallel to the second direction X (i.e., it is inclined), the positions of the third side-side connecting end, which is the end on the third side of the first connecting stepped surface 24c, and the fourth side-side connecting end, which is the end on the fourth side, in the first direction Y do not coincide.

[0132] Figure 17 is a schematic perspective view showing an example of a sheet-like wick that can be used in the housing shown in Figure 16. The substantially rectangular portion 127 constituting the sheet-like wick 214 shown in Figure 17 has the same configuration as the substantially rectangular portion 120 constituting the sheet-like wick 210 shown in Figure 8, except that a cutout portion 128 is provided in place of the slit 125, where the sheet-like wick is cut out at a predetermined position. Therefore, the length LS of the substantially rectangular portion 127 in the first direction Y １ This is the length LB of the bottom surface 20 of the housing 100 shown in Figure 3 in the first direction Y. １ The length LS of the roughly rectangular portion 127 in the second direction X is the same as the length LS of the roughly rectangular portion 127. ２ This is the length LB in the second direction X of the bottom surface 20 of the housing 100 shown in Figure 3. ２ It is longer than that.

[0133] The cutout portion 128 is intended to deform the roughly rectangular portion 127 and place it on the bottom surface 20 of the housing 101. However, the length of the cutout portion 128 in the second direction X does not match the length of the first connecting step surface 24c in the second direction X, and the length of the cutout portion 128 is longer than the length of the first connecting step surface 24c.

[0134] The position of the cutout portion 128 is determined by points A, B, C, and D, which are obtained by the following procedure. Point A is the point that coincides with the third side connection end, which is the end of the first connection step surface 24c closest to the third side surface 50, when the third side surface 127c of the roughly rectangular portion 127 is aligned with the third side surface 50 of the housing 101. Point B is the point that coincides with the fourth side connection end, which is the end of the first connection step surface 24c closest to the fourth side surface 60, when the third side surface 127c of the roughly rectangular portion 127 is aligned with the third side surface 50 of the housing 101. Point C is the point that coincides with the fourth side connection end, which is the end of the first connection step surface 24c closest to the fourth side surface 60, when the fourth side surface 127d of the roughly rectangular portion 127 is aligned with the fourth side surface 60 of the housing 101. Point D is the point that coincides with the third side connection end, which is the end of the first connection step surface 24c closest to the third side surface 50, when the fourth side surface 127d of the roughly rectangular portion 127 is aligned with the fourth side surface 60 of the housing 101. The cutout portion 128 is provided at the position connecting points A, B, C, and D. By providing the cutout portion 128 at this position, the roughly rectangular portion 127 can continuously cover the first bottom surface 21, the second bottom surface 22, the first step surface 24a, and the second step surface 24b of the housing 101.

[0135] The sheet-like wick 214 has a first part 214A and a second part 214B. The first part 214A is the portion that continuously covers the first bottom surface 21, the first stepped surface 24a, and the second bottom surface 22 of the housing 101 along the second direction X, and in Figure 17, it is the portion on the first side surface 127a side of the extension lines that extend points B and C towards the third side surface 127c and the fourth side surface 127d in the second direction X. The second part 214B is the portion that continuously covers the first bottom surface 21, the second stepped surface 24b, and the second bottom surface 22 of the housing 101 along the second direction X, and in Figure 17, it is the portion on the second side surface 127b side of the extension lines that extend points A and D towards the third side surface 127c and the fourth side surface 127d in the second direction X.

[0136] The housing constituting the heat diffusion device of the present invention may further have a step, which is a third step surface arranged parallel to a first direction, and a second connecting step surface that is substantially parallel to a second direction and connects the end of the first step surface or the end of the second step surface in the first direction with the end of the third step surface. An example of a housing having such a step will be described with reference to Figures 18, 19, 20, 21, 22, 23, and 24.

[0137] Figure 18 is a top view showing yet another example of the enclosure.

[0138] In the housing 102 shown in Figure 18, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is positioned on the first side surface 30 side of the first stepped surface 25a in the first direction Y, and on the fourth side surface 60 side of the first stepped surface in the second direction X. The second connecting stepped surface 25e connects the end of the first stepped surface 25a and the end of the third stepped surface 25d in the first direction Y. A step 25 of this shape can be described as a staircase type, based on the shape of the second bottom surface 22.

[0139] Figure 19 is a top view showing yet another example of the enclosure.

[0140] In the housing 103 shown in Figure 19, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is located on the first side surface 30 side of the first stepped surface 25a in the first direction Y, and is positioned between the first stepped surface 25a and the second stepped surface 25b in the second direction X. The second connecting stepped surface 25e connects the end of the first stepped surface 25a and the end of the third stepped surface 25d in the first direction Y. A stepped surface 25 of this shape can be described as an asymmetrical concave shape with respect to the shape of the second bottom surface 22.

[0141] Figure 20 is a top view showing yet another example of the enclosure.

[0142] In the housing 104 shown in Figure 20, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is located on the first side surface 30 side of the first stepped surface 25a in the first direction Y, and at the same position as the second stepped surface 25b in the second direction X. The second connecting stepped surface 25e connects the end of the first stepped surface 25a and the end of the third stepped surface 25d in the first direction Y. The first connecting stepped surface 25c is parallel to the second connecting stepped surface 25e, and their lengths are equal in the second direction X. A stepped surface 25 of this shape can be described as a symmetrical concave shape with respect to the shape of the second bottom surface 22.

[0143] Figure 21 is a top view showing yet another example of the enclosure.

[0144] In the housing 105 shown in Figure 21, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is positioned on the first side surface 30 side of the first stepped surface 25a in the first direction Y, and on the third side surface 50 side of the second stepped surface 25b in the second direction X, and the second connecting stepped surface 25e connects the end of the first stepped surface 25a and the end of the third stepped surface 25d in the first direction Y. A step 25 of this shape can be described as an asymmetrical concave shape with respect to the shape of the second bottom surface 22.

[0145] Figure 22 is a top view showing yet another example of the enclosure.

[0146] In the housing 106 shown in Figure 22, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is located on the second side surface 40 side of the second stepped surface 25b in the first direction Y, and is positioned between the first stepped surface 25a and the second stepped surface 25b in the second direction X. The second connecting stepped surface 25e connects the end of the second stepped surface 25b and the end of the third stepped surface 25d in the first direction Y. The shape of such a step 25 can be said to be an asymmetrical convex shape with respect to the shape of the second bottom surface 22.

[0147] Figure 23 is a top view showing yet another example of the enclosure.

[0148] In the housing 107 shown in Figure 23, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is located on the second side surface 40 side of the second stepped surface 25b in the first direction Y, and at the same position as the first stepped surface 25a in the second direction X. The second connecting stepped surface 25e connects the end of the second stepped surface 25b and the end of the third stepped surface 25d in the first direction Y. The shape of such a step 25 can be said to be a convex shape that is symmetrical with respect to the shape of the second bottom surface 22.

[0149] Figure 24 is a top view showing yet another example of the enclosure.

[0150] In the housing 108 shown in Figure 24, a step 25 is provided between the first bottom surface 21 and the second bottom surface 22. The step 25 consists of a first step surface 25a, a second step surface 25b, a first connecting step surface 25c, a third step surface 25d, and a second connecting step surface 25e. The first step surface 25a, the second step surface 25b, and the third step surface 25d are all parallel to the first direction Y. The second step surface 25b is located on the third side surface 50 side of the first step surface 25a in the second direction X, and on the second side surface 40 side of the first step surface 25a in the first direction Y. The end of the first step surface 25a and the end of the second step surface 25b in the first direction Y are connected by the first connecting step surface 25c. The third stepped surface 25d is positioned on the second side surface 40 side of the second stepped surface 25b in the first direction Y, and on the fourth side surface 60 side of the first stepped surface 25a in the second direction X. The second connecting stepped surface 25e connects the end of the second stepped surface 25b and the end of the third stepped surface 25d in the first direction Y. The shape of such a step 25 can be said to be an asymmetrical convex shape with respect to the shape of the second bottom surface 22.

[0151] Note that when using the housings shown in Figures 18 to 24, the sheet-like wicks shown in Figures 8 to 15 and Figure 17 cannot be used. For the housings shown in Figures 18 to 24, for example, a sheet-like wick with slits formed at positions corresponding to the first and second connecting stepped surfaces of the housing can be prepared, and a wick that has been bent at positions corresponding to the first, second, and third stepped surfaces of the housing can be combined with it.

[0152] 1 Heat diffusion device 10 Top surface of the housing 20 Bottom surface of the housing 21 First bottom surface 21A First bottom surface A section 21B First bottom surface B section 22 Second bottom surface 22A Second bottom surface A section 22B Second bottom surface B section 23, 24, 25 Steps 23a, 24a, 25a First step surface 23b, 24b, 25b Second step surface 23c, 24c, 25c First connecting step surface 25d Third step surface 25e Second connecting step surface 30 First side surface of the housing 40 Second side surface of the housing 50 Third side surface of the housing 60 Fourth side surface of the housing 100, 101, 102, 103, 104, 105, 106, 107, 108 Housing 120, 127 Approximately rectangular shape section 120a, 127a First side of roughly rectangular portion 120b, 127b Second side of roughly rectangular portion 120c, 127c Third side of roughly rectangular portion 120d, 127d Fourth side of roughly rectangular portion 121, 121' First bottom covering portion 121a, 121'a, 221a First bottom A covering portion 121b, 121'b, 221b First bottom B covering portion 122, 122' Second bottom covering portion 122a, 122'a, 222a Second bottom A covering portion 122b, 122'b, 222b Second bottom B covering portion 123a, 123'a First stepped surface covering portion 123b, 123'b Second stepped surface covering portion 125, 125' Slit 128 Cut-out section 130, 140 Folding section 130a First part of folding section 130b Second part of folding section 130c Third part of folding section 120' Second roughly rectangular section 120'a First side of second roughly rectangular section 120'a Second side of second roughly rectangular section 120'a Third side of second roughly rectangular section 120'a Fourth side of second roughly rectangular section 200 Wick 210, 211, 212, 213, 214 Sheet-like wick 200A, 210A, 214A, 220A First part of wick 200B, 210B, 214B Second part of wick 220 Second sheet-like wick 220a First side of second sheet-like wick 220b Second side of second sheet-like wick 220c Third side of the second sheet-like wick 220d Fourth side of the second sheet-like wick 221a First bottom surface A covering portion 221b First bottom surface B covering portion 222a Second bottom surface A covering portion 222b Second bottom surface B covering portion223a First stepped surface covering portion 223c First connecting stepped surface covering portion A １ First area A ２ Second area B Reference line F ２１ First fold line F ２２ Second fold line F ２３ Third fold line F ２４ Fourth fold line F ３０ F ３１ F ４０ F ４１ F ４２ F ４３ F ４４ Boundary line P １ Third side slit end P ２ Third side slit bent portion P ３ Fourth side slit folding portion P ４ Fourth side slit end TB １ Distance from the top surface to the first bottom surface TB ２ Distance from the top surface to the second bottom surface TB ３ａ Height of the first step surface TB ３ｂ Height of the second step surface TB ３ｃ Height of the first connecting step surface LB １ Length of the base 20 in the first direction: LB ２ Length of the base 20 in the second direction: LB ３ａ Length of the first step surface in the first direction LB ３ｂ Length of the second step surface in the first direction LB ３ｃ Length of the first connecting step surface in the second direction LS １ Length of the sheet-like wick in the first direction LS ２ Length of the sheet-like wick in the second direction LS ３ Length of the first bottom surface A covering portion in the first direction LS ４ Length of the second sheet-like wick in the second direction LS ５ Length of the slit in the second direction

Claims

1. A thermal diffusion device comprising a housing, a wick and a working medium disposed in the internal space of the housing, wherein the housing has a top surface and a bottom surface having a first bottom surface and a second bottom surface facing the top surface in the thickness direction, a step is provided between the first bottom surface and the second bottom surface, the minimum distance between the top surface and the first bottom surface is smaller than the minimum distance between the top surface and the second bottom surface, the step has a first step surface parallel to a first direction perpendicular to the thickness direction, a second step surface parallel to the first direction, and a first connecting step surface not parallel to the first direction that connects the end of the first step surface and the end of the second step surface in the first direction, The wick comprises a first portion that continuously covers the first bottom surface, the first stepped surface, and the second bottom surface of the housing along a second direction perpendicular to the thickness direction and the first direction, and a second portion that continuously covers the first bottom surface, the second stepped surface, and the second bottom surface of the housing along a second direction, wherein a discontinuous portion is provided between the portion of the first portion of the wick that covers the first bottom surface of the housing and the portion of the second portion of the wick that covers the second bottom surface, along the first connecting stepped surface, the wick is not continuous in the first direction, thus forming a thermal diffusion device.

2. The thermal diffusion device according to claim 1, wherein the wick is bonded to the first bottom surface, the second bottom surface, the first stepped surface, and the second stepped surface of the housing by diffusion bonding.

3. The heat diffusion device according to claim 1 or 2, wherein a support column is arranged between the top surface of the housing and the wick.

4. The thermal diffusion device according to any one of claims 1 to 3, wherein the internal space of the housing is partitioned by a first side surface and a second side surface facing the first direction, and a third side surface and a fourth side surface facing the second direction, and the second stepped surface is positioned on the third side surface side of the first stepped surface in the second direction, and on the second side surface side of the first stepped surface in the first direction.

5. The heat diffusion device according to claim 4, wherein the wick consists of a single sheet-like wick having a substantially rectangular portion having a first side surface and a second side surface facing the first direction, and a third side surface and a fourth side surface facing the second direction, and having a slit provided along the second direction in the substantially rectangular portion, and the substantially rectangular portion of the sheet-like wick is disposed on the bottom surface of the housing.

6. The substantially rectangular portion of the sheet-like wick has a substantially rectangular shape, the length in the first direction being substantially the same as the length of the bottom surface of the housing in the first direction, and the length in the second direction being substantially the same as the length of the bottom surface of the housing in the second direction plus the length of the first stepped surface or the second stepped surface in the thickness direction, and the slit is provided at a position that linearly connects the third side slit end, which is the point where the sheet-like wick overlaps with the third side side connection end, which is the point on the third side side of the first connecting stepped surface closest to the third side when the third side of the substantially rectangular portion is aligned with the third side of the housing, to the fourth side slit end, which is the point where the sheet-like wick overlaps with the fourth side side connection end, which is the point on the fourth side of the first connecting stepped surface when the fourth side of the substantially rectangular portion is aligned with the fourth side of the housing, and the sheet-like wick is mountain-folded in the first fold line that connects the third side slit end and the second side by the shortest distance. In the second fold line connecting the third side slit bend portion, which is a point moved from the end of the third side slit along the second direction to the fourth side by the length of the second step surface in the thickness direction, and the second side by the shortest distance, the sheet-like wick is valley-folded; in the fourth fold line connecting the end of the fourth side slit and the first side by the shortest distance, the sheet-like wick is valley-folded; in the third fold line connecting the fourth side slit bend portion, which is a point moved from the end of the fourth side slit along the second direction to the third side by the length of the first step surface in the thickness direction, and the first side by the shortest distance, the sheet-like wick is mountain-folded. Of the substantially rectangular portion, the first bottom covering portion, which is the portion demarcated by the first side, the third side, the second side, the third fold line, the slit, and the first fold line, covers the first bottom surface of the housing, and the second bottom covering portion, which is the portion demarcated by the first side, the fourth side, the second side, the fourth fold line, the slit, and the second fold line, covers the second bottom surface of the housing.The thermal diffusion device according to claim 5, wherein the second stepped surface covering portion, which is the region of the substantially rectangular-shaped portion sandwiched between the first fold line and the second fold line in the second direction, covers the second stepped surface of the housing, and the first stepped surface covering portion, which is the region of the substantially rectangular-shaped portion sandwiched between the third fold line and the fourth fold line in the second direction, covers the first stepped surface of the housing.

7. The heat diffusion device according to claim 5 or 6, wherein the sheet-like wick has a folded portion continuous with the substantially rectangular portion in addition to the substantially rectangular portion, and a part of the folded portion folded toward the substantially rectangular portion covers the first connecting step surface.

8. When the first bottom surface is divided into a first bottom surface A portion which is the portion on the third side side of the second step surface in the second direction, and a first bottom surface B portion which is the portion on the fourth side side of the second step surface, and the second bottom surface is divided into a second bottom surface A portion which is the portion on the fourth side side of the first step surface in the second direction, and a second bottom surface B portion which is the portion on the third side side of the first step surface, the folding portion has a first portion which is continuous with the second side side of the second bottom surface B covering portion which is the portion of the substantially rectangular shape portion that covers the second bottom surface B portion, and covers the second bottom surface B portion when folded, a second portion which is continuous with the first portion on the side opposite to the second side, and covers the first connecting step surface when folded, and a third portion which is continuous with the second portion on the side opposite to the second side, and covers the first bottom surface B portion when folded, and the sheet-like wick is valley-folded at the boundary line between the second bottom surface B covering portion and the first portion. The thermal diffusion device according to claim 7, wherein the sheet-like wick is mountain-folded at the boundary between the first and second parts, and the sheet-like wick is valley-folded at the boundary between the second and third parts.

9. The sheet-like wick has a second substantially rectangular portion, which is the same shape as the substantially rectangular portion, on the side opposite to the second side of the third portion of the folding portion, and is continuous with the third portion, and covers the first bottom surface A, first bottom surface B, second bottom surface A, second bottom surface B, first stepped surface and second stepped surface of the housing when folded. The heat diffusion device according to claim 8, wherein the folding portion is folded toward the substantially rectangular portion, so that the first portion, second portion, and third portion of the folding portion cover the second bottom surface B portion, the first connecting step surface, and the first bottom surface B portion of the housing, respectively, and the second substantially rectangular portion is folded toward the folding portion and bent in the same manner as the substantially rectangular portion, so that the first bottom surface A portion, the first bottom surface B portion, the second bottom surface A portion, the second bottom surface B portion, the first step surface, and the second step surface of the housing are covered by the second substantially rectangular portion.

10. When the first bottom surface is divided into a first bottom surface A portion which is the portion on the third side side of the second stepped surface in the second direction, and a first bottom surface B portion which is the portion on the fourth side side of the second stepped surface, and the second bottom surface is divided into a second bottom surface A portion which is the portion on the fourth side side of the first stepped surface in the second direction, and a second bottom surface B portion which is the portion on the third side side of the first stepped surface, The folding portion comprises a first bottom surface A covering portion having substantially the same shape as the first bottom surface A portion, a first bottom surface B covering portion having substantially the same shape as the first bottom surface B portion and provided continuously with the first bottom surface A covering portion on the fourth side side of the first bottom surface A covering portion, a first stepped surface covering portion having substantially the same shape as the first stepped surface and provided continuously with the first bottom surface B covering portion on the fourth side side of the first bottom surface B covering portion, a second bottom surface A covering portion having substantially the same shape as the second bottom surface A portion and provided continuously with the first stepped surface covering portion on the fourth side side of the first stepped surface covering portion, and a first connecting stepped surface covering portion having substantially the same shape as the first connecting stepped surface and provided continuously from the first bottom surface B covering portion on the substantially rectangular portion side of the first bottom surface B covering portion, and the The heat diffusion device according to claim 7, wherein the folding portion is folded toward the substantially rectangular portion, and the first bottom A portion, first bottom B portion, first stepped surface, second bottom A portion, first connecting stepped surface, and second bottom B portion of the housing are covered by the first bottom A portion, first bottom B portion, first stepped surface, second bottom A portion, first connecting stepped surface, and second bottom B portion of the folding portion, respectively.

11. The wick is formed by laminating the sheet-like wick and the second sheet-like wick, and the first bottom surface is divided into a first bottom surface A portion which is the portion on the third side side of the second stepped surface in the second direction, and a first bottom surface B portion which is the portion on the fourth side side of the second stepped surface, and the second bottom surface is divided into a second bottom surface A portion which is the portion on the fourth side side of the first stepped surface in the second direction, and a second bottom surface B portion which is the portion on the third side side of the first stepped surface, The second sheet-like wick comprises a first bottom surface A covering portion having substantially the same shape as the first bottom surface A portion, a first bottom surface B covering portion having substantially the same shape as the first bottom surface B portion and provided continuously with the first bottom surface A covering portion on the fourth side surface of the first bottom surface A covering portion, a first stepped surface covering portion having substantially the same shape as the first stepped surface and provided continuously with the first bottom surface B covering portion on the fourth side surface of the first bottom surface B covering portion, and the first stepped surface covering portion on the fourth side surface of the first stepped surface covering portion The heat diffusion device according to claim 6, comprising: a second bottom surface A covering portion having substantially the same shape as the second bottom surface A portion and provided in a continuous manner with the first bottom surface A portion; a first connecting step surface covering portion having substantially the same shape as the first connecting step surface and provided in a continuous manner from the first bottom surface B covering portion on the second side side of the first connecting step surface covering portion; and a second bottom surface B covering portion having substantially the same shape as the second bottom surface B portion and provided in a continuous manner from the first connecting step surface covering portion on the second side side of the first connecting step surface covering portion.

12. The thermal diffusion device according to claim 4, wherein the step further comprises a third step surface arranged parallel to the first direction, and a second connecting step surface connecting the end of the first step surface or the end of the second step surface in the first direction to the end of the third step surface.

13. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the first side of the first stepped surface in the first direction and on the fourth side of the first stepped surface in the second direction.

14. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the first side of the first stepped surface in the first direction, and between the first stepped surface and the second stepped surface in the second direction.

15. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the first side of the first stepped surface in the first direction and at the same position as the second stepped surface in the second direction.

16. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the first side of the first stepped surface in the first direction and on the third side of the second stepped surface in the second direction.

17. The thermal diffusion device according to claim 12, wherein the third stepped surface is located on the second side of the second stepped surface in the first direction, and is positioned between the first stepped surface and the second stepped surface in the second direction.

18. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the second side of the second stepped surface in the first direction, and at the same position as the first stepped surface in the second direction.

19. The thermal diffusion device according to claim 12, wherein the third stepped surface is positioned on the second side of the second stepped surface in the first direction, and on the fourth side of the first stepped surface in the second direction.

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