HEAT DIFFUSING DEVICE, ELECTRONIC APPARATUS, AND WICK FOR HEAT DIFFUSING DEVICE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International application No. PCT/JP2024/011602, filed March 25, 2024, which claims priority to Japanese Patent Application No. 2023-051748, filed March 28, 2023, the entire contents of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a heat diffusing device, an electronic apparatus, and a wick for the heat diffusing device.

BACKGROUND ART

In recent years, the amount of heat generation due to high integration and high performance of elements has increased. In addition, with the progress of downsizing of products, a heat generation density increases, and heat dissipation measures are therefore important. This situation is particularly remarkable in the field of mobile terminals such as smartphones and tablets. As a heat countermeasure member, a graphite sheet or other members are often used, but the heat transport amount is not sufficient; therefore, various heat countermeasure members are being studied for use. Among them, as a heat diffusing device capable of diffusing heat very effectively, a vapor chamber that is a heat pipe having a planar shape is being studied for use.

The vapor chamber has a structure in which, in a housing, a working medium (also referred to as a working fluid) and a wick to transport the working medium by capillary force are sealed. The working medium absorbs heat from a heat generation element such as an electronic component in an evaporation part that absorbs heat from the heat generation element, thereby evaporates in a vapor chamber, moves in the vapor chamber, is cooled, and returns to a liquid phase. The working medium having returned to the liquid phase moves again to the evaporation part on the heat generation element side by the capillary force of the wick and cools the heat generation element. By repeating this, the vapor chamber independently operates without external power, and can two-dimensionally diffuse heat at a high speed by using evaporation latent heat and condensation latent heat of the working medium.

Patent Literature 1 discloses a vapor chamber including: a housing including an upper housing sheet and a lower housing sheet that are joined to face each other at outer edge portions thereof, the housing having an internal space; a working fluid sealed in the internal space; a microchannel that is disposed in the internal space of the lower housing sheet and constitutes a flow path for the working fluid; and a wick having a sheet shape and disposed in the internal space of the housing so as to be in contact with the microchannel, in which a contact area between the wick and the microchannel is 5% to 40% with respect to an area in a plan view of the internal space.

Patent Literature 1: WO 2021/229961 A

SUMMARY OF THE DISCLOSURE

In the vapor chamber described in Patent Literature 1, the working fluid that has released heat in the internal space of the housing and returned to the liquid moves through the microchannel by capillary force due to the holes of the wick, and is conveyed again near the heat source. However, when the wick disposed in the internal space of the housing and the convex portion of the microchannel formed in the lower housing sheet are not sufficiently in close contact with each other, the liquid working medium is hardly transported to the vicinity of the heat source, so that a maximum heat transport amount of the vapor chamber may be reduced.

The above problem is not limited to the vapor chamber, and is a problem common to heat diffusing devices capable of diffusing heat by the same configuration as the vapor chamber.

The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a heat diffusing device having a large heat transport amount. Furthermore, an object of the present disclosure is to provide an electronic apparatus including the heat diffusing device and a wick for the heat diffusing device.

A heat diffusing device of the present disclosure includes: a housing that includes a first inner surface and a second inner surface facing each other in a thickness direction and defining an internal space; a working medium sealed in the internal space of the housing; and a wick having a sheet shape disposed in the internal space of the housing. The wick includes a first through-hole penetrating the wick in the thickness direction, and a second through-hole penetrating the wick in the thickness direction. A first protrusion protruding toward the first inner surface is on a peripheral edge of the first through-hole. A second protrusion protruding toward the second inner surface is on a peripheral edge of the second through-hole.

The electronic apparatus of the present disclosure includes the heat diffusing device of the present disclosure.

A wick for the heat diffusing device of the present disclosure is a wick having a sheet shape and including a first through-hole penetrating the wick in a thickness direction and a second through-hole penetrating the wick in the thickness direction. A first protrusion protruding in a first direction in the thickness direction is on a peripheral edge of the first through-hole. A second protrusion protruding in a second direction in the thickness direction opposite to the first direction is on a peripheral edge of the second through-hole.

The present disclosure can provide a heat diffusing device having a large heat transport amount. Furthermore, the present disclosure can provide an electronic apparatus including the heat diffusing device and a wick for the heat diffusing device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically illustrating an example of a heat diffusing device according to a first embodiment of the present disclosure.

FIG. 2 is a cross-sectional view schematically illustrating an example of the heat diffusing device according to the first embodiment of the present disclosure.

FIG. 3 is a perspective view schematically illustrating an example of a wick constituting the heat diffusing device according to the first embodiment of the present disclosure.

FIG. 4 is a plan view of the wick illustrated in FIG. 3.

FIG. 5 is a cross-sectional view of the wick illustrated in FIG. 4 taken along line A-A.

FIG. 6 is a cross-sectional view of the wick illustrated in FIG. 4 taken along line B-B.

FIG. 7 is a cross-sectional view schematically illustrating an example of the heat diffusing device at a position different from that in FIG. 2.

FIG. 8 is a cross-sectional view schematically illustrating an example of a shape of a first protrusion.

FIG. 9 is a cross-sectional view schematically illustrating another example of the shape of the first protrusion.

FIG. 10 is a perspective view schematically illustrating an example of a heat diffusing device according to a second embodiment of the present disclosure.

FIG. 11 is a cross-sectional view schematically illustrating an example of the heat diffusing device according to the second embodiment of the present disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a heat diffusing device of the present disclosure will be described.

However, the present disclosure is not limited to the following embodiments, and can be appropriately modified and be applied without changing the gist of the present disclosure. A combination of two or more of individual preferred configurations of the present disclosure described below is also the present disclosure.

The heat diffusing device of the present disclosure may be, for example, a vapor chamber having a planar shape, or may be a heat pipe having a tubular shape.

Note that a wick for a heat diffusing device described below is also one aspect of the present disclosure.

Each embodiment shown below is an example, and it goes without saying that partial replacement or combination of configurations described in different embodiments is possible. In a second embodiment and the subsequent embodiments, the matters common to the first embodiment will not be described, and only the differences will be described. In particular, the same operation and effect by the same configuration will not be mentioned each time in each embodiment.

In the following description, each embodiment is simply referred to as a "heat diffusing device of the present disclosure" unless otherwise distinguished.

The drawings shown below are schematic views, and dimensions, scales of aspect ratios, and the like may be different from those of actual products. In the drawings, the same or corresponding parts are denoted by the same reference signs. In each drawing, the same elements are denoted by the same reference signs, and redundant description will be omitted.

In the present specification, terms (for example, "vertical", "parallel", and "orthogonal") indicating relationships between elements and terms indicating shapes of elements are not expressions representing only strict meanings, but are expressions meaning to include substantially equivalent ranges containing, for example, about several percent difference. Furthermore, in the present specification, "equivalent" or "constant" is not an expression meaning only a case of being completely equivalent or constant, but is an expression meaning to include a case of being substantially equivalent or constant, for example, a case of including about several percent difference.

First Embodiment

FIG. 1 is a perspective view schematically illustrating an example of a heat diffusing device according to the first embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically illustrating an example of the heat diffusing device according to the first embodiment of the present disclosure. FIG. 2 is an example of a cross- sectional view of the heat diffusing device illustrated in FIG. 1 taken along line II-II.

A vapor chamber (heat diffusing device) 1 illustrated in FIGS. 1 and 2 includes a hollow housing 10 hermetically sealed in an airtight state. The housing 10 includes a first inner surface 11a and a second inner surface 12a facing each other in a thickness direction Z. The housing 10 is provided with an internal space. The vapor chamber 1 further includes: a working medium 20 sealed in the internal space of the housing 10; and a wick 30 having a sheet shape and disposed in the internal space of the housing 10. The vapor chamber 1 may further include a support column 40 disposed in the internal space of the housing 10.

An evaporation part in which the enclosed working medium 20 is evaporated is set in the housing 10. As illustrated inFIG. 1, a heat source HS, which is a heat generation element, is disposed on an outer surface of the housing 10. Examples of the heat source HS include an electronic component, such as a central processing unit (CPU), for an electronic apparatus. A part that constitutes the internal space of the housing 10 and that is in the vicinity of the heat source HS and heated by the heat source HS corresponds to the evaporation part.

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

A size of the vapor chamber 1, that is, a size of the housing 10 is not limited. A width and length of the vapor chamber 1 can be appropriately set depending on applications. The width and length of the vapor chamber 1 are each, for example, 5 mm to 500 mm, 20 mm to 300 mm, or 50 mm to 200 mm. The width and length of the vapor chamber 1 may be the same or different.

The housing 10 is preferably formed of a first sheet 11 and a second sheet 12 that face each other and whose outer edge portions are joined.

When the housing 10 is configured with the first sheet 11 and the second sheet 12, a material constituting the first sheet 11 and the second sheet 12 is not limited as long as the material has characteristics suitable for use as a heat diffusing device such as a vapor chamber, for example, thermal conductivity, strength, flexibility, and pliability. The material constituting the first sheet 11 and the second sheet 12 is preferably metal, for example, copper, nickel, aluminum, magnesium, titanium, iron, or an alloy containing these metals as a main component, and is particularly preferably copper. The materials constituting the first sheet 11 and the second sheet 12 may be the same or different, but are preferably the same.

When the housing 10 is configured with the first sheet 11 and the second sheet 12, the first sheet 11 and the second sheet 12 are joined to each other at the outer edge portions thereof. The joining method is not limited, but, for example, laser welding, resistance welding, diffusion joining, brazing, TIG welding (tungsten-inert gas welding), ultrasonic joining, or resin sealing can be used, and laser welding, resistance welding, or brazing can be preferably used.

The thickness of each of the first sheet 11 and the second sheet 12 is not limited, but is preferably 10 m to 200 m, more preferably 30 m to 100 m, and still more preferably 40 m to 60 m. The thicknesses of the first sheet 11 and the second sheet 12 may be the same or different. In addition, the thickness of each of the first sheet 11 and the second sheet 12 may be the same throughout the sheet, or may be partially thin.

The shape of the first sheet 11 and the second sheet 12 is not limited. For example, each of the first sheet 11 and the second sheet 12 may have a shape in which its outer edge portion is thicker than the portion other than the outer edge portion.

The thickness of the entire vapor chamber 1 is not limited, but is preferably 50 m to 500 m. A height of the internal space of the housing 10 is not limited, but is preferably 30 m to 400 m.

A planar shape of the housing 10 as viewed in the thickness direction Z is not limited, and examples thereof include a polygon such as a triangle or a rectangle, a circle, an ellipse, and a combination thereof. The planar shape of the housing 10 may be an L shape, a C shape (U shape), a staircase shape, or the like. The housing 10 may have a penetration opening. The planar shape of the housing 10 may be a shape corresponding to the followings: a purpose of use of a heat diffusing device such as a vapor chamber; a shape of a place where the heat diffusing device is incorporated; and other components in the vicinity of the heat diffusing device.

The working medium 20 is not limited as long as the working medium 20 can cause a gas-liquid phase change under an environment in the housing 10, and, for example, water, alcohols, or alternative fluorocarbon can be used. For example, the working medium 20 is an aqueous compound, and is preferably water.

The wick 30 has a capillary structure capable of moving the working medium 20 by capillary force.

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

A size and shape of the wick 30 are not limited as long as the wick has a sheet shape, but, for example, the wick 30 is preferably continuously disposed in the internal space of the housing 10. The wick 30 may be disposed in the entire internal space of the housing 10 when viewed from the thickness direction Z, and the wick 30 may be disposed in a part of the internal space of the housing 10 when viewed from the thickness direction Z.

As illustrated in FIG. 2, a support column 40 in contact with the second inner surface 12a may be disposed in the internal space of the housing 10. The housing 10 and the wick 30 can be supported by disposing the support column 40 in the internal space of the housing 10.

The material constituting the support column 40 is not limited, and examples thereof include resin, metal, ceramic, or a mixture or a laminated article thereof. Further, as illustrated in FIG. 2, the support column 40 may be integrated with the housing 10, and may be formed by, for example, etching the second inner surface 12a of the housing 10.

A shape of the support column 40 is not limited as long as the shape can support the housing 10 and the wick 30, but examples of the shape of the cross-section perpendicular to the height direction of the support column 40 include a polygon such as a rectangle, a circle, or an ellipse.

As illustrated in FIG. 2, the support column 40 may have a tapered shape in which the width decreases from the second inner surface 12a of the housing 10 toward the wick 30. As a result, the flow path between the support columns 40 can be wider on the wick 30 side.

FIG. 3 is a perspective view schematically illustrating an example of the wick constituting the heat diffusing device according to the first embodiment of the present disclosure. FIG. 4 is a plan view of the wick illustrated in FIG. 3.

The wick 30 having a sheet shape includes first through-holes 61 penetrating the wick 30 in the thickness direction Z and second through-holes 62 penetrating the wick 30 in the thickness direction Z.

The first through-holes 61 and the second through-holes 62 can be formed, for example, by punching a metal foil constituting the wick 30 by press working.

In the first through-holes 61 and the second through-holes 62, the working medium 20 can move by a capillary phenomenon. The shapes of the first through-holes 61 and the second through-holes 62 are not limited, but cross-sections in a plane perpendicular to the thickness direction Z preferably have a circular shape or an elliptic shape. The shape of the first through-holes 61 and the shape of the second through-holes 62 may be the same or different.

FIG. 5 is a cross-sectional view of the wick illustrated in FIG. 4 taken along line A-A.

As illustrated in FIG. 5, peripheral edges of the first through-holes 61 are each provided with a first protrusion 71 that protrudes in one direction in the thickness direction (a negative direction in the thickness direction Z in FIG. 5). In the example shown in FIG. 2, in the vapor chamber 1, the first protrusions 71 protrude in a direction toward the first inner surface 11a.

The first protrusions 71 are provided on the peripheral edges of the first through- holes 61; therefore, in the vapor chamber 1 illustrated in FIG. 2, a liquid flow path through which the liquid working medium 20 moves is formed between the wick 30 and the first inner surface 11a of the housing 10.

Unlike Patent Literature 1, since the first protrusions 71 are integrally formed with the wick 30, adhesion of the first protrusions 71 with the wick 30 is not deteriorated. Therefore, the maximum heat transport amount can be improved as compared with Patent Literature 1. Furthermore, since the liquid flow path can be formed by the first protrusions 71, it is not always necessary to form a microchannel by processing the first inner surface 1 la of the housing 10 as in Patent Literature 1.

The first protrusions 71 may or may not be in contact with the first inner surface 11a of the housing 10. When the first protrusions 71 are in contact with the first inner surface 11a, the first protrusions 71 may or may not be joined to the first inner surface 11a.

The wick 30 may include at least one first through-hole 61 whose peripheral edge is provided with a first protrusion 71. The first protrusion 71 may be provided only on a part of the peripheral edge of the first through-hole 61, but is preferably provided on the entire peripheral edge of the first through-hole 61.

FIG. 6is a cross-sectional view of the wick illustrated in taken along line B-B. FIG. 7 is a cross-sectional view schematically illustrating an example of the heat diffusing device at a position different from that in FIG. 2.

As illustrated in FIG. 6, peripheral edges of the second through-holes 62 are each provided with a second protrusion 72 that protrudes in the opposite direction in the thickness direction (a positive direction in the thickness direction Z in FIG. 6). In the example shown in FIG. 7, in the vapor chamber 1, the second protrusions 72 protrude in a direction toward the second inner surface 12a.

In the vapor chamber 1 illustrated in FIG. 7, a vapor space in which vapor of the working medium 20 moves is configured between the wick 30 and the second inner surface 12a of the housing 10. At this time, the vaporized working medium 20 can be efficiently moved to the vapor space by the second through-holes 62 on the peripheral edges of which the second protrusions 72 are provided.

From the viewpoint of forming the liquid flow path while securing a sufficient vapor space, as illustrated in FIGS. 2 and 7, a distance between the wick 30 and the first inner surface 1 la is preferably smaller than a distance between the wick 30 and the second inner surface 12a, in the thickness direction Z.

When the support columns 40 are disposed in the internal space of the housing 10, the second protrusions 72 may or may not be in contact with the support columns 40. When the second protrusions 72 are in contact with the support columns 40, the second protrusions 72 may or may not be joined to the support columns 40.

As illustrated in FIG. 7, when the second protrusions 72 are in contact with the support columns 40, there is a space (a region indicated by P in FIG. 7) between the wick 30 and the support columns 40. Since the space P can be used as a vapor flow path through which vapor of the working medium 20 moves, the heat transport amount of the vapor chamber 1 can be increased as compared with the case where the second protrusions 72 are not provided.

The wick 30 may include at least one second through-hole 62 whose peripheral edge is provided with a second protrusion 72. The second protrusion 72 may be provided only on a part of the peripheral edge of the second through-hole 62, but is preferably provided on the entire peripheral edge of the second through-hole 62.

The first protrusions 71 and the second protrusions 72 can be formed, for example, by punching the metal foil constituting the wick 30 by press working. In this case, the first protrusions 71 may be formed simultaneously with the first through-holes 61 or may be formed separately from the first through-holes 61. Similarly, the second protrusions 72 may be formed simultaneously with the second through-holes 62, or may be formed separately from the second through-holes 62. In punching by press working, the shapes and the like of the first protrusions 71 and the second protrusions 72 can be adjusted by appropriately adjusting a depth and the like of the punching. The depth of punching means, for example, how much a punch is pushed in a punching direction when punching is performed with the punch.

The shape of the first protrusions 71 is not limited.

FIG. 8 is a cross-sectional view schematically illustrating an example of the shape of the first protrusion.

As illustrated in FIG. 8, a distance between the outer walls of the first protrusion 71 may be smaller toward a tip end of the first protrusion 71 (toward the lower side in FIG. 8). That is, the first protrusion 71 may have a tapered shape. In this case, the first protrusion 71 may have a shape protruding toward the tip end side (lower side in FIG. 8) of the first protrusion 71 or a shape protruding toward a base end side (upper side in FIG. 8) of the first protrusion 71, on a cross-section along the thickness direction.

FIG. 9 is a cross-sectional view schematically illustrating another example of the shape of the first protrusion.

As illustrated in FIG. 9, the first protrusion 71 may have a lid portion that narrows the first through-hole 61 at the tip end.

In the case where the first protrusion 71 has a tapered shape, in the example illustrated in FIG. 2, if the distance between the outer walls of the first protrusion 71 is smaller toward the first inner surface 11 a of the housing 10, a pressure loss in the liquid flow path can be reduced.

Although not illustrated, the distance between the outer walls of the first protrusions 71 may be larger toward the tip end of the first protrusions 71. That is, the first protrusion 71 may have a reversely tapered shape. In this case, the first protrusion 71 may have a shape protruding toward the tip end side of the first protrusion 71 or a shape protruding toward a base end side of the first protrusion 71, on a cross-section along the thickness direction. The first protrusion 71 may have a lid portion that narrows the first through-hole 61 at the tip end.

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

Similarly, the shape of the second protrusion 72 is not limited.

For example, the distance between the outer walls of the second protrusion 72 may be narrowed toward the tip end of the second protrusion 72. That is, the second protrusion 72 may have a tapered shape. In this case, the second protrusion 72 may have a shape protruding toward the tip end side of the second protrusion 72 or a shape protruding toward a base end side of the second protrusion 72, on a cross-section along the thickness direction. The second protrusion 72 may have a lid portion that narrows the second through- hole 62 at the tip end.

In the case where the second protrusion 72 has a tapered shape, in the example illustrated in FIG. 7, if the distance between the outer walls of the second protrusion 72 is smaller toward the second inner surface 12a of the housing 10, a pressure loss in the vapor flow path can be reduced.

The distance between the outer walls of the second protrusion 72 may be larger toward the tip end of the second protrusion 72. That is, the second protrusion 72 may have a reversely tapered shape. In this case, the second protrusion 72 may have a shape protruding toward the tip end side of the second protrusion 72 or a shape protruding toward a base end side of the second protrusion 72, on a cross-section along the thickness direction. The second protrusion 72 may have a lid portion that narrows the second through-hole 62 at the tip end.

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

A diameter of the first through-hole 61 whose peripheral edge is provided with the first protrusion 71 is not limited, but is, for example, 5 m to 100 m. In a case where the diameter of the first through-hole 61 is different in the thickness direction Z, the diameter of the smallest part is defined as the diameter of the first through-hole 61.

A diameter of the second through-hole 62 whose peripheral edge is provided with the second protrusion 72 is not limited, but is, for example, 5 m to 100 m. In a case where the diameter of the second through-hole 62 is different in the thickness direction Z, the diameter of the smallest portion is defined as the diameter of the second through-hole 62.

The diameter of the first through-hole 61 and the diameter of the second through- hole 62 may be the same or different, but the diameter of the first through-hole 61 and the diameter of the second through-hole 62 are preferably the same.

As illustrated in FIG. 4 and other figures, the wick 30 preferably includes a plurality of the first through-holes 61. In this case, the shapes, diameters, and the like of the first through-holes 61 may be the same or different.

An arrangement of the first through-holes 61 is not limited, but the first through- holes 61 are preferably arranged evenly in a predetermined region, more preferably evenly over the entire region such that, for example, a center-to-center distance (pitch) between the first through-holes 61 adjacent to each other is constant.

When the center-to-center distance between the adjacent first through-holes 61 is constant, the liquid working medium 20 can be uniformly distributed in a plane viewed from the thickness direction Z. Therefore, the characteristics of the vapor chamber 1 can be made uniform.

The center-to-center distance between the adjacent first through-holes 61 is not limited, but is, for example, 30 m to 150 m.

As illustrated in FIG. 4 and other figures, the wick 30 preferably includes a plurality of the second through-holes 62. In this case, the shapes, diameters, and the like of the second through-holes 62 may be the same or different.

An arrangement of the second through-holes 62 is not limited, but the second through-holes 62 are preferably arranged evenly in a predetermined region, more preferably evenly over the entire region such that, for example, a center-to-center distance (pitch) between the second through-holes 62 adjacent to each other is constant.

When the center-to-center distance between the adjacent second through-holes 62 is constant, the vapor of the working medium 20 can be uniformly distributed in a plane viewed from the thickness direction Z. Therefore, the characteristics of the vapor chamber 1 can be made uniform.

The center-to-center distance between the adjacent second through-holes 62 is not limited, but is, for example, 30 m to 150 m. The center-to-center distance between the adjacent second through-holes 62 may be the same as or different from the center-to-center distance between the adjacent first through-holes 61.

The wick 30 preferably includes a plurality of the first through-holes 61 and a plurality of the second through-holes 62. An arrangement of the first through-holes 61 and an arrangement of the second through-holes 62 are not limited, but a center-to-center distance between the first through-hole 61 and the second through-hole 62 adjacent to each other is preferably constant.

When the center-to-center distance between the first through-hole 61 and the second through-hole 62 adjacent to each other is constant, the wick 30 can be suppressed from warping.

The center-to-center distance between the first through-hole 61 and the second through-hole 62 adjacent to each other is not limited, but is, for example, 20 m to 100 m.

A height (length indicated by t1 in FIG. 5) of each first protrusion 71 is, for example, 10 um to 100 um.

A height (length indicated by t₂ in FIG. 6) of each second protrusion 72 is, for example, 10 um to 100 um.

The height t₁ of the first protrusions 71 is preferably equivalent to the height t₂ of the second protrusions 72. In this case, since the shape of the wick 30 is the same even when the wick 30 is reversed in the thickness direction Z, it is easy to handle the wick 30 when disposing the wick 30 in the internal space of the housing 10.

Furthermore, at least one of the height ti of the first protrusion 71 and the height t₂ of the second protrusions 72 is preferably larger than a conductor thickness (length indicated by to in FIGS. 5 and 6) of the wick 30. In particular, the height ti of the first protrusions 71 is preferably larger than the conductor thickness to of the wick 30, and the height t₂ of the second protrusions 72 is preferably larger than the conductor thickness to of the wick 30.

When the height t₁ of the first protrusions 71 is larger than the conductor thickness to of the wick 30, the first protrusions 71 are sufficiently high, so that the liquid flow path is easily formed. On the other hand, when the height t₂ of the second protrusions 72 is larger than the conductor thickness to of the wick 30, the second protrusions 72 are sufficiently high, so that the vapor flow path is easily formed.

Note that the conductor thickness to of the wick 30 means a thickness of the conductor portion of the wick 30. When the thickness of the conductor portion is not constant in the sheet, a thickness of a portion where the thickness is at its maximum is defined as the conductor thickness to of the wick 30. The conductor thickness to of the wick 30 is not limited, but is, for example, 5 um to 100 um.

In a case where the wick 30 includes a plurality of the first through-holes 61, the shapes, heights, and the like of the first protrusions 71 may be the same or different.

In a case where the wick 30 includes a plurality of the second through-holes 62, the shapes, heights, and the like of the second protrusions 72 may be the same or different.

In addition to the first through-hole 61 whose peripheral edge is provided with the first protrusion 71 and the second through-hole 62 whose peripheral edge is provided with the second protrusion 72, the wick 30 may further include a third through-hole that is not provided with a first protrusion 71 or a second protrusion 72.

When the support columns 40 are disposed in the internal space of housing 10, a height of the support columns 40 is, for example, 50 um to 1,000 um.

In the cross-section illustrated in FIGS. 2 or 7, a width of each support column 40 is not limited as long as the support column 40 provides enough strength to suppress the housing 10 from deforming, but a circle equivalent diameter of a cross-section perpendicular to the height direction of an end part of the support column 40 on the wick 30 side is, for example, 100 m to 2,000 m, preferably 300 m to 1,000 m. By increasing the circle equivalent diameter of the support columns 40, deformation of the housing 10 can be further suppressed. On the other hand, by reducing the circle equivalent diameter of the support columns 40, it is possible to secure a wider space for the vapor of the working medium 20 to move.

When a plurality of the support columns 40 are disposed in the internal space of the housing 10, the shapes, heights, and the like of the support columns 40 may be the same or different.

An arrangement of the support columns 40 is not limited, but the support columns 40 are preferably arranged evenly in a predetermined region, more preferably evenly over the entire region such that, for example, a center-to-center distance (pitch) between the support columns 40 adjacent to each other is constant. By uniformly arranging the support columns 40, uniform strength can be ensured over the entire heat diffusing device such as a vapor chamber. The center-to-center distance between the support columns 40 is, for example, 100 um to 10,000 um.

Second Embodiment

FIG. 10 is a perspective view schematically illustrating an example of a heat diffusing device according to a second embodiment of the present disclosure. FIG. 11 is a cross-sectional view schematically illustrating the example of the heat diffusing device according to the second embodiment of the present disclosure. Note that FIG. 11 is an example of a cross-sectional view of the heat diffusing device illustrated in FIG. 10 taken along line XI-XI.

As in a heat diffusing device 2 illustrated in FIGS. 10 and 11, a support column is not required to be disposed in an internal space of a housing 10.

The heat diffusing device 2 may have a planar shape or a tubular shape as a whole. That is, the housing 10 may have a planar shape or a tubular shape as a whole. Here, the "tubular shape" means a shape in which either the width or the length is 10 times or more the thickness. When the heat diffusing device 2 has a tubular shape as a whole, a shape of the tube is not limited, and examples thereof include a rectangular tube shape, a cylindrical shape, and an elliptical tube shape.

Other Embodiments

The heat diffusing device of the present disclosure is not limited to the above embodiments, and various applications and modifications can be made within the scope of the present disclosure regarding the configuration, manufacturing conditions, and the like of the heat diffusing device.

In the heat diffusing device of the present disclosure, the housing may have one evaporation part or a plurality of evaporation parts. That is, on an outer wall surface of the housing, one heat source or a plurality of heat sources may be disposed.

In the heat diffusing device of the present disclosure, in a case where the housing is configured with a first sheet and a second sheet, the first sheet and the second sheet may overlap each other such that end portions of the first sheet and the second sheet coincide with each other, or may overlap each other such that the end portions of the first sheet and the second sheet are shifted from each other.

In the heat diffusing device of the present disclosure, in a case where the housing is configured with a first sheet and a second sheet, the material constituting the first sheet and the material constituting the second sheet may be different from each other. For example, by using for the first sheet a material having high strength, stress applied to the housing can be distributed. Further, by using different materials for the two sheets, one sheet can provide one function, and the other sheet can provide another function. The above functions are not limited, and examples thereof include a thermal conduction function and an electromagnetic wave shielding function.

The heat diffusing device of the present disclosure can be mounted on an electronic apparatus for the purpose of heat dissipation. Therefore, an electronic apparatus including the heat diffusing device of the present disclosure is also one aspect of the present disclosure. Examples of the electronic apparatus of the present disclosure include a smartphone, a tablet terminal, a laptop computer, a game device, and a wearable device. As described above, the heat diffusing device of the present disclosure operates independently without requiring external power, and can two-dimensionally diffuse heat at a high speed using evaporation latent heat and condensation latent heat of a working medium. Therefore, the electronic apparatus including the heat diffusing device of the present disclosure can effectively achieve heat dissipation in a limited space inside the electronic apparatus.

The heat diffusing device of the present disclosure can be used in a wide range of applications in the field of portable information terminals and the like. For example, the heat diffusing device can be used to lower the temperature of a heat source such as a CPU and extend time of use of an electronic apparatus, and can be used for a smartphone, a tablet terminal, a laptop computer, and other devices.

REFERENCE SIGNS LIST

1: vapor chamber (heat diffusing device)

2: heat diffusing device

10: housing

11: first sheet

11a: first inner surface

12: second sheet

12a: second inner surface

20: working medium

30: wick

40: support column

61: first through-hole

62: second through-hole

71: first protrusion

72: second protrusion

t₀: conductor thickness of wick

t₁: height of first protrusion

t2: height of second protrusion

HS: heat source

P: space between wick and support columns

X: width direction

Y: length direction

Z: thickness direction