WO2023026896A1

WO2023026896A1 - Thermal diffusion device

Info

Publication number: WO2023026896A1
Application number: PCT/JP2022/030944
Authority: WO
Inventors: 浩士福田
Original assignee: 株式会社村田製作所
Priority date: 2021-08-24
Filing date: 2022-08-16
Publication date: 2023-03-02

Abstract

A thermal diffusion device 1 comprises a housing 10, a working medium 20 enclosed in an interior space of the housing 10, and a wick 30 that is disposed in the interior space of the housing 10 and forms at least a part of the surface of a liquid flow path 40 of the working medium 20. The liquid flow path 40 has an upper surface 41 that is separated from an inner wall surface of the housing 10, and a side surface 42 that is continuous with the upper surface 41 and contacts the inner wall surface of the housing 10. The wick 30 includes a porous sheet 31 and a porous sintered body 32 provided on at least a part of the porous sheet 31. In the first embodiment, the minimum pore size of the porous sheet 31 is larger than the maximum pore size of the porous sintered body 32. Moreover, in the second embodiment, the porous sheet 31 is a nonwoven fabric.

Description

heat spreading device

The present invention relates to heat diffusion devices.

In recent years, the amount of heat generated has increased due to the high integration and high performance of devices. In addition, as products become smaller, heat generation density increases, so heat dissipation measures have become important. This situation is particularly pronounced in the field of mobile terminals such as smartphones and tablets. A graphite sheet or the like is often used as a heat countermeasure member, but its heat transfer capacity is not sufficient, so the use of various heat countermeasure members has been investigated. Among them, as a heat diffusion device capable of diffusing heat very effectively, the use of a vapor chamber, which is a planar heat pipe, is being studied.

The vapor chamber has a structure in which a working medium (also called a working fluid) and a wick composed of a porous body that transports the working medium by capillary force are sealed inside a housing. The working medium absorbs heat from a heat-generating element such as an electronic component in an evaporating section that absorbs heat from the heat-generating element, evaporates in the vapor chamber, moves in the vapor chamber, and is cooled to a liquid phase. return. The working medium that has returned to the liquid phase moves again to the evaporating portion on the heating element side by the capillary force of the wick, and cools the heating element. By repeating this, the vapor chamber can operate independently without external power, and heat can be two-dimensionally diffused at high speed by utilizing the latent heat of vaporization and latent heat of condensation of the working medium.

Patent Document 1 discloses a flat container in which a working fluid is enclosed, and a wick provided inside the container. and a linear bundle in which fibers thicker than the fibers are linearly bundled, and the linear bundle is arranged in a cavity surrounded by the inner peripheral surface of the braided body, and is arranged around the braided body. discloses a heat pipe characterized in that a vapor channel for the working fluid is formed, and a liquid channel for the working fluid is formed in the cavity.

JP 2018-76989 A

In the heat pipe described in Patent Document 1, by changing the thickness of the fiber used as the material of the wick, the wick is formed with an inner region and an outer region, and the inner region is used as a liquid flow path and the outer region. is the steam flow path.

However, when the wick is composed of fibers in the vapor chamber, there is a trade-off between the capillary force of the wick and the permeability. Therefore, it is difficult to obtain sufficient liquid transport performance.

Also, in making the vapor chamber thinner, it is necessary to make the wick thinner. Under such circumstances, for example, when the wick is composed of a porous sintered body such as a metal porous sintered body, cracks or dents are likely to occur in the porous sintered body due to strength problems. Therefore, there is a possibility that the liquid transport performance may deteriorate.

It should be noted that the above problem is not limited to vapor chambers, but is common to heat diffusion devices capable of diffusing heat with a configuration similar to that of vapor chambers.

An object of the present invention is to provide a heat diffusion device with a highly durable wick and excellent liquid transport performance. A further object of the present invention is to provide an electronic device comprising the above heat diffusion device.

A heat diffusion device of the present invention includes a housing, a working medium enclosed in the internal space of the housing, and a liquid flow path of the working medium disposed in the internal space of the housing. a forming wick; The liquid channel has an upper surface remote from the inner wall surface of the housing and a side surface continuous with the upper surface and in contact with the inner wall surface of the housing. The wick includes a porous sheet and a porous sintered body provided on at least part of the porous sheet.

In the first aspect of the heat diffusion device of the present invention, the minimum pore size of the porous sheet is larger than the maximum pore size of the porous sintered body. Moreover, in the second aspect, the porous sheet is a nonwoven fabric.

The electronic device of the present invention includes the heat diffusion device of the present invention.

According to the present invention, it is possible to provide a heat diffusion device with a highly durable wick and excellent liquid transport performance. Furthermore, according to the present invention, it is possible to provide an electronic device comprising the above heat diffusion device.

FIG. 1 is a perspective view schematically showing an example of a heat diffusion device according to a first embodiment of the invention. 2 is a plan view schematically showing an example of the internal structure of the heat diffusion device shown in FIG. 1. FIG. 3 is a cross-sectional view of the heat spreading device shown in FIG. 2 along line III-III. FIG. 4 is a perspective view schematically showing an example of a liquid channel. FIG. 5 is a cross-sectional view schematically showing another example of the heat diffusion device according to the first embodiment of the invention. FIG. 6 is a cross-sectional view schematically showing still another example of the heat diffusion device according to the first embodiment of the invention. FIG. 7 is a plan view schematically showing an example of a support. FIG. 8 is a cross-sectional view schematically showing an example of a heat diffusion device according to the second embodiment of the invention. FIG. 9 is a cross-sectional view schematically showing another example of the heat diffusion device according to the second embodiment of the invention. FIG. 10 is a cross-sectional view schematically showing an example of a heat diffusion device according to the third embodiment of the invention. FIG. 11 is a plan view schematically showing another example of the support. FIG. 12 is a cross-sectional view schematically showing an example of a heat diffusion device according to the fourth embodiment of the invention. FIG. 13 is a plan view schematically showing an example of a heat diffusion device according to the fifth embodiment of the invention. 14 is a cross-sectional view of the heat spreading device shown in FIG. 13 along line XIV-XIV. 15 is a cross-sectional view of the heat spreading device shown in FIG. 13 along line XV-XV. FIG. 16 is a plan view schematically showing an example of the internal structure of a heat diffusion device in which a plurality of wicks are arranged. FIG. 17 is a plan view schematically showing an example of the internal structure of a heat diffusion device whose housing has a plurality of evaporators. FIG. 18 is a plan view schematically showing another example of the internal structure of a heat diffusion device whose housing has a plurality of evaporators.

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

Generally, in a heat diffusion device such as a vapor chamber, a liquid-phase working medium is transported while passing through the inside of a wick. For example, when the wick is composed of a bundle of fibers as described in Patent Document 1, as a method for enhancing the liquid transport performance to the evaporator, the inside of the wick has a dense structure to increase the capillary pressure. can be considered to be higher. However, when the inside of the wick has a dense structure, the fluid resistance passing through the inside of the wick increases and the permeability decreases, so the liquid transport performance deteriorates accordingly. In addition, as the heat diffusion device becomes thinner, the thinner the wick, the more difficult it becomes to secure the volume of the liquid flow path and to reduce the fluid resistance.

On the other hand, in the heat diffusion device of the present invention, the wick forms at least a part of the surface of the liquid flow path of the working medium, thereby forming a cavity that serves as the liquid flow path of the working medium. Therefore, not only can capillary pressure be generated by the wick around the cavity, but also the working medium can smoothly flow through the cavity by reducing fluid resistance passing through the cavity. As a result, the transmittance can be increased.

Furthermore, the heat diffusion device of the present invention uses a wick having a porous sintered body provided on at least a portion of the porous sheet. Among these, the porous sheet functions as a reinforcing material for holding the porous sintered body. As a result, the porous sintered body is less likely to develop cracks, dents, or the like. Therefore, the durability of the wick can be enhanced as compared with the case where the wick is composed only of the porous sintered body.

More specifically, in the first aspect of the heat diffusion device of the present invention, the minimum pore size of the porous sheet is larger than the maximum pore size of the porous sintered body. Moreover, a 2nd aspect WHEREIN: A porous sheet is a nonwoven fabric.

In the first aspect and the second aspect, the porous sheet operates without impairing the capillary pressure of the porous sintered body by making the pore size of the porous sheet larger than the pore size of the porous sintered body. It can contribute to the liquid flow path of the medium. As a result, high liquid transport performance can be exhibited.

Each embodiment shown below is an example, and it goes without saying that partial replacement or combination of configurations shown in different embodiments is possible. In the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only different points will be described. In particular, similar actions and effects due to similar configurations will not be mentioned sequentially for each embodiment.

In the following description, when each embodiment is not particularly distinguished, it is simply referred to as "the heat diffusion device of the present invention".

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

The drawings shown below are schematic, and their dimensions and aspect ratio may differ from the actual product.

[First embodiment]
In the heat diffusion device according to the first embodiment of the present invention, the porous sheet is in contact with the upper surface of the liquid channel, and the porous sintered body is in contact with the side surface of the liquid channel. Further, a support for supporting the wick is arranged along the extending direction of the liquid channel in the internal space of the housing.

FIG. 1 is a perspective view schematically showing an example of the heat diffusion device according to the first embodiment of the invention. 2 is a plan view schematically showing an example of the internal structure of the heat diffusion device shown in FIG. 1. FIG. 3 is a cross-sectional view of the heat spreading device shown in FIG. 2 along line III-III.

A vapor chamber (heat diffusion device) 1 shown in FIG. 1 includes a hollow housing 10 that is hermetically sealed. As shown in FIG. 2, the housing 10 is provided with an evaporation portion EP for evaporating the enclosed working medium 20 (see FIG. 3). As shown in FIG. 1, a heat source HS, which is a heating element, is arranged on the outer wall surface of the housing 10 . Examples of the heat source HS include electronic components of electronic equipment, such as a central processing unit (CPU). A portion of the internal space of the housing 10 that is in the vicinity of the heat source HS and is heated by the heat source HS corresponds to the evaporating section EP.

The housing 10 has, for example, a first inner wall surface 11a and a second inner wall surface 12a facing each other in the thickness direction Z, as shown in FIG. In that case, the housing 10 is preferably composed of a first sheet 11 and a second sheet 12 that face each other and whose outer edges are joined.

The vapor chamber 1 is preferably planar as a whole. That is, the housing 10 as a whole is preferably planar. Here, the “planar shape” includes a plate shape and a sheet shape, and the dimension in the width direction X (hereinafter referred to as width) and the dimension in the length direction Y (hereinafter referred to as length) are the thickness direction Z Shapes that are considerably large relative to their dimensions (hereinafter referred to as thickness or height), for example shapes whose width and length are 10 times or more, preferably 100 times or more, the thickness.

The size of the vapor chamber 1, that is, the size of the housing 10 is not particularly limited. The width and length of the vapor chamber 1 can be appropriately set according to the application. The width and length of the vapor chamber 1 are, for example, 5 mm or more and 500 mm or less, 20 mm or more and 300 mm or less, or 50 mm or more and 200 mm or less. The width and length of vapor chamber 1 may be the same or different.

When the housing 10 is composed of the first sheet 11 and the second sheet 12, the materials that constitute the first sheet 11 and the second sheet 12 should have properties suitable for use as a vapor chamber, such as thermal conductivity, strength, and the like. , flexibility, flexibility, etc., and is not particularly limited. The material that constitutes the first sheet 11 and the second sheet 12 is preferably a metal, such as copper, nickel, aluminum, magnesium, titanium, iron, or an alloy containing them as a main component. Copper is particularly preferable. is. The materials forming 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 composed of the first sheet 11 and the second sheet 12, the first sheet 11 and the second sheet 12 are joined together at their outer edge portions. The method of such bonding 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, preferably can use laser welding, resistance welding or brazing.

The thicknesses of the first sheet 11 and the second sheet 12 are not particularly limited, but each is preferably 10 μm or more and 200 μm or less, more preferably 30 μm or more and 100 μm or less, still more preferably 40 μm or more and 60 μm or less. The thicknesses of the first sheet 11 and the second sheet 12 may be the same or different. Further, the thickness of each sheet of the first sheet 11 and the second sheet 12 may be the same over the entire area, or may be thin in part.

The shapes of the first sheet 11 and the second sheet 12 are not particularly limited. For example, the first sheet 11 may have a flat plate shape with a constant thickness, and the second sheet 12 may have a shape in which the outer edge portion is thicker than the portions other than the outer edge portion.

Alternatively, the first sheet 11 may have a flat plate shape with a constant thickness, and the second sheet 12 may have a constant thickness and a portion other than the outer edge with respect to the outer edge may be convex outward. good. In this case, a recess is formed in the outer edge of the housing 10 . Therefore, the concave portion of the outer edge can be used when mounting the vapor chamber. Also, other components can be placed in the recesses of the outer edge.

Although the thickness of the entire vapor chamber 1 is not particularly limited, it is preferably 50 μm or more and 500 μm or less.

The planar shape of the housing 10 when viewed from the thickness direction Z is not particularly limited, and examples thereof include polygonal shapes such as triangles and rectangles, circular shapes, elliptical shapes, and shapes combining these shapes. Further, the planar shape of the housing 10 may be L-shaped, C-shaped (U-shaped), step-shaped, or the like. Moreover, the housing 10 may have a through hole. The planar shape of the housing 10 may be a shape according to the use of the vapor chamber, the shape of the location where the vapor chamber is installed, and other parts existing nearby.

As shown in FIG. 3, in the vapor chamber 1, the working medium 20 is enclosed in the internal space of the housing 10.

The working medium 20 is not particularly limited as long as it can cause a gas-liquid phase change in the environment inside the housing 10. For example, water, alcohols, CFC alternatives, etc. can be used. For example, the working medium is an aqueous compound, preferably water.

A wick 30 is arranged in the internal space of the housing 10 . The wick 30 has a capillary structure capable of moving the working medium 20 by capillary force.

As shown in FIG. 3 , the liquid channel 40 of the working medium 20 is formed by the wick 30 forming at least a part of the surface of the liquid channel 40 of the working medium 20 . On the other hand, a vapor channel 50 for the working medium 20 is formed in a gap other than the liquid channel 40 inside the housing 10 .

FIG. 4 is a perspective view schematically showing an example of a liquid channel.

As shown in FIGS. 3 and 4, the liquid channel 40 has a top surface 41 that is separated from the inner wall surface of the housing 10, a side surface 42 that is continuous with the top surface 41 and is in contact with the inner wall surface of the housing 10, have In the example shown in FIGS. 3 and 4, the liquid flow path 40 is formed in which the upper surface 41 is separated from the first inner wall surface 11a of the housing 10 and the side surface 42 is in contact with the first inner wall surface 11a of the housing 10. However, the liquid channel 40 may be formed such that the upper surface 41 is separated from the second inner wall surface 12 a of the housing 10 and the side surface 42 is in contact with the second inner wall surface 12 a of the housing 10 . Thus, in this specification, the upper surface of the liquid channel means the surface away from the inner wall surface of the housing, and does not mean the surface positioned vertically upward.

Although the width of the liquid channel 40 in a cross section perpendicular to the extending direction (here, the length direction Y) of the liquid channel 40 is not particularly limited, it is, for example, 500 μm or more and 3000 μm or less. In the above cross section, when the width of the liquid channel 40 differs in the thickness direction Z, the width of the widest portion is defined as the width of the liquid channel 40 .

The wick 30 includes a porous sheet 31 and a porous sintered body 32 provided on at least part of the porous sheet 31 .

In the first aspect, the minimum pore size of the porous sheet 31 is larger than the maximum pore size of the porous sintered body 32 .

The pore diameter of the porous sheet 31 means the diameter of a circle inscribed in the pore formed on the surface of the porous sheet 31 when the wick 30 is viewed from the thickness direction Z. Similarly, the pore diameter of the porous sintered body 32 means the diameter of a circle inscribed in the pores formed on the surface of the porous sintered body 32 when the wick 30 is viewed from the thickness direction Z. do.

In the first aspect, the porous sheet 31 may be an etched porous plate in which pores are formed by etching a metal plate, like the vapor chamber 1 shown in FIG. Since the etching porous plate is formed from a flat metal plate, the porous sheet 31 has excellent flatness.

FIG. 5 is a cross-sectional view schematically showing another example of the heat diffusion device according to the first embodiment of the invention.

In the first aspect, the porous sheet 31 may be a mesh like the vapor chamber 1a shown in FIG. The mesh that is the material of the porous sheet 31 may be composed of, for example, a metal mesh, a resin mesh, or a surface-coated mesh thereof, preferably a copper mesh, a stainless steel (SUS) mesh, or a polyester mesh. Configured. By using a mesh as the porous sheet 31, the wick 30 can be manufactured at low cost.

FIG. 6 is a cross-sectional view schematically showing yet another example of the heat diffusion device according to the first embodiment of the invention.

In the second aspect, the porous sheet 31 is a nonwoven fabric like the vapor chamber 1b shown in FIG. The material of the nonwoven fabric is not particularly limited. By using a nonwoven fabric as the porous sheet 31, the wick 30 can be manufactured at low cost.

In the first and second aspects, the porous sintered body 32 may be composed of, for example, a metal porous sintered body or a ceramic porous sintered body, preferably a metal porous sintered body. It is composed of a solid body, and more preferably composed of a porous sintered body of copper or nickel.

As a method of manufacturing the wick 30 constituting the vapor chamber 1 shown in FIG. 3, for example, a paste containing metal powder or ceramic powder is applied to the surface of the porous sheet 31 and then fired to form a porous sheet. A method of forming a porous sintered body 32 on the surface of 31, and the like. The thickness of the porous sintered body 32 can be easily controlled by adjusting the amount of paste containing metal powder or ceramic powder applied to the surface of the porous sheet 31 . On the other hand, the porous sintered body 32 located on the side surface 42 of the liquid channel 40 can be formed by, for example, directly applying a paste containing metal powder or ceramic powder to the housing 10 and then firing the paste. . For example, a paste containing metal powder or ceramic powder is directly applied to the housing 10, and the porous sheet 31 having the paste applied to the surface is placed thereon, followed by simultaneous firing to form a porous sintered body. 32 may be formed. Alternatively, a paste containing metal powder or ceramic powder is directly applied to the housing 10, the porous sheet 31 is placed thereon, the paste is applied to the surface of the porous sheet 31, and then co-fired. The porous sintered body 32 may be formed by

In the vapor chamber 1 shown in FIG. 3, the porous sheet 31 is in contact with the upper surface 41 of the liquid channel 40.

In the vapor chamber 1 shown in FIG. 3, the porous sintered body 32 is exposed on the surface of the wick 30. As shown in FIG. 3, it is preferable that the porous sintered body 32 is exposed over the entire surface of the wick 30 .

Further, in the internal space of the housing 10, a support 60 that supports the wick 30 is arranged along the extension direction of the liquid channel 40 (here, the length direction Y). In the example shown in FIG. 3, two rows of supports 60 are arranged parallel to each other along the extending direction of the liquid flow channel 40, but only one row of supports along the extending direction of the liquid flow channel 40 is provided. 60 may be arranged, or three or more rows of supports 60 may be arranged so as to be parallel to each other along the extending direction of the liquid channel 40 .

When the support 60 is arranged in the internal space of the housing 10, the support 60 supports the wick 30 like a tent. Therefore, even if the wick 30 is thin as the vapor chamber is thinned, the liquid channel 40 is less likely to collapse, and the volume of the liquid channel 40 can be secured.

In the example shown in FIG. 3 , a support 60 is arranged to support the first inner wall surface 11 a of the housing 10 and the wick 30 . A body 60 may be arranged. In that case, the support 60 on the second inner wall surface 12a side preferably faces the support 60 on the first inner wall surface 11a side.

The material forming the support 60 is not particularly limited, but examples include resins, metals, ceramics, or mixtures and laminates thereof. Further, as shown in FIG. 3, the support 60 may be integrated with the housing 10, or may be formed by etching the inner wall surface of the housing 10, for example.

FIG. 7 is a plan view schematically showing an example of a support.

As shown in FIG. 7, the support 60 included in the vapor chamber 1 shown in FIG. 3 includes a plurality of struts 61 arranged at intervals along the extending direction (here, the length direction Y) of the liquid channel 40. It is preferably composed of In this case, the porous sintered body 32 is in contact with the side surface 42 of the liquid channel 40 . Therefore, the side surface 42 of the liquid channel 40 can also be used as a gas-liquid exchange portion.

When the support 60 is composed of a plurality of struts 61, the shape of the cross section perpendicular to the height direction of the struts 61 may be, for example, a polygon such as a rectangle, a circle, an ellipse, or the like.

When the support 60 is composed of a plurality of struts 61, the heights of the struts 61 may be the same or different in one vapor chamber. For example, the height of the struts 61 in one region may differ from the height of the struts 61 in another region.

When the support 60 is composed of a plurality of struts 61, the width of the struts 61 is not particularly limited as long as it provides the strength to support the wick 30. is, for example, 100 μm or more and 2000 μm or less, preferably 300 μm or more and 1000 μm or less.

When the support 60 is composed of a plurality of struts 61, the arrangement of the struts 61 is not particularly limited. More preferably, the struts 61 are arranged so that the distance is constant.

The end of the wick 30 is preferably fixed to the inner wall surface of the housing 10. For example, when the porous sintered body 32 is made of metal, the end of the wick 30 is preferably joined to the inner wall surface of the housing 10 . Although the bonding method is not particularly limited, diffusion bonding or the like can be used, for example.

The wick 30 is preferably fixed to the support 60. For example, when the porous sheet 31 and the porous sintered body 32 are made of metal, the wick 30 is preferably bonded to the support 60 . Although the bonding method is not particularly limited, diffusion bonding or the like can be used, for example.

In the second and subsequent embodiments described below, the minimum pore size of the porous sheet 31 is larger than the maximum pore size of the porous sintered body 32 in the first aspect. The porous sheet 31 may be, for example, an etched perforated plate or a mesh. Moreover, in the second aspect, the porous sheet 31 is a nonwoven fabric.

[Second embodiment]
In the heat diffusion device according to the second embodiment of the present invention, the porous sintered body is in contact with the upper surface of the liquid channel and the porous sintered body is in contact with the side surface of the liquid channel. Further, a support for supporting the wick is arranged along the extending direction of the liquid channel in the internal space of the housing.

FIG. 8 is a cross-sectional view schematically showing an example of a heat diffusion device according to the second embodiment of the invention.

In the vapor chamber (heat diffusion device) 2 shown in FIG. 8, the porous sintered body 32 is in contact with the upper surface 41 of the liquid channel 40. This facilitates gas-liquid exchange compared to the case where the porous sheet 31 is in contact with the upper surface 41 of the liquid channel 40 .

A porous sintered body 32 is provided on one side of a porous sheet 31 in the vapor chamber 2 shown in FIG. Therefore, the porous sheet 31 is exposed on the surface of the wick 30 . As shown in FIG. 8, it is preferable that the porous sheet 31 is exposed over the entire surface of the wick 30 .

Further, in the internal space of the housing 10, a support 60 that supports the wick 30 is arranged along the extension direction of the liquid channel 40 (here, the length direction Y).

The support 60 included in the vapor chamber 2 shown in FIG. 8 includes a plurality of supports arranged at intervals along the extension direction (here, the length direction Y) of the liquid channel 40 as shown in FIG. It is preferably composed of a strut 61 . In this case, the porous sintered body 32 is in contact with the side surface 42 of the liquid channel 40 .

FIG. 9 is a cross-sectional view schematically showing another example of the heat diffusion device according to the second embodiment of the invention.

In the vapor chamber (thermal diffusion device) 2a shown in FIG. 9, the porous sintered body 32 is in contact with the upper surface 41 of the liquid channel 40, as in the vapor chamber 2 shown in FIG.

In the vapor chamber 2a shown in FIG. 9, porous sintered bodies 32 are provided on both sides of a porous sheet 31. Therefore, the porous sintered body 32 is exposed on the surface of the wick 30 . As shown in FIG. 9, it is preferable that the porous sintered body 32 is exposed over the entire surface of the wick 30 .

As a method of manufacturing the wick 30 constituting the vapor chamber 2 shown in FIG. 8, for example, similar to the wick 30 constituting the vapor chamber 1 shown in FIG. For example, a method of forming a porous sintered body 32 on the surface of the porous sheet 31 by coating the surface of the porous sheet 31 and then firing the porous sheet 31 . On the other hand, the porous sintered body 32 located on the side surface 42 of the liquid channel 40 can be formed by, for example, directly applying a paste containing metal powder or ceramic powder to the housing 10 and then firing the paste. . As described above, the porous sintered body 32 may be formed by co-firing. In that case, the boundary between the porous sintered body 32 located on the upper surface 41 of the liquid channel 40 and the porous sintered body 32 located on the side surface 42 of the liquid channel 40 does not appear clearly.

As a method of manufacturing the wick 30 that constitutes the vapor chamber 2a shown in FIG. A method of forming a porous sintered body 32 on the surface and the like can be mentioned. The method of immersing the porous sheet 31 in a paste containing metal powder or ceramic powder allows the wick 30 to be produced more easily than the method of applying the paste to both surfaces of the porous sheet 31 . On the other hand, the porous sintered body 32 located on the side surface 42 of the liquid channel 40 can be formed by, for example, directly applying a paste containing metal powder or ceramic powder to the housing 10 and then firing the paste. . As described above, the porous sintered body 32 may be formed by co-firing. In that case, the boundary between the porous sintered body 32 located on the upper surface 41 of the liquid channel 40 and the porous sintered body 32 located on the side surface 42 of the liquid channel 40 does not appear clearly.

In the third and subsequent embodiments described below, the porous sheet may be in contact with the upper surface of the liquid channel, and the porous sintered body may be in contact with the upper surface of the liquid channel.

[Third embodiment]
In the heat diffusion device according to the third embodiment of the present invention, the porous sintered body is not in contact with the side surfaces of the liquid channels.

FIG. 10 is a cross-sectional view schematically showing an example of a heat diffusion device according to the third embodiment of the invention.

　In the vapor chamber (heat diffusion device) 3 shown in FIG. Thereby, the width of the wick 30 can be made smaller than when the porous sintered body 32 is in contact with the side surface 42 of the liquid channel 40 . Therefore, the volume of the steam flow path 50 is easily ensured.

FIG. 11 is a plan view schematically showing another example of the support.

The support 60 included in the vapor chamber 3 shown in FIG. 10 is a support that forms the side surface 42 of the liquid channel 40 along the extending direction (here, the length direction Y) of the liquid channel 40, as shown in FIG. It preferably consists of a wall 62 .

[Fourth embodiment]
In the heat diffusion device according to the fourth embodiment of the present invention, no support is arranged in the internal space of the housing.

FIG. 12 is a cross-sectional view schematically showing an example of a heat diffusion device according to the fourth embodiment of the invention.

In the vapor chamber (heat diffusion device) 4 shown in FIG. 12, unlike the vapor chamber 1 and the like shown in FIG.

In the vapor chamber 4 shown in FIG. 12, the porous sintered body 32 is in contact with the side surface 42 of the liquid channel 40. Therefore, the side surface 42 of the liquid channel 40 can also be used as a gas-liquid exchange section.

In the vapor chamber 4 shown in FIG. 12, the width of the porous sintered body 32 in the portion in contact with the side surface 42 of the liquid flow path 40 is adjusted so that the wick 30 can stand on its own. It is preferable that the width of the portion of the porous sintered body 32 that is in contact with the side surface 42 of the flow path 40 is larger than that of the porous sintered body 32 . Specifically, the width of the porous sintered body 32 in the portion in contact with the side surface 42 of the liquid channel 40 in the vapor chamber 4 shown in FIG. It is preferably equal to the sum of the width of the porous sintered body 32 in contact with the side surface 42 and the width of the support 60 .

[Fifth embodiment]
In the heat diffusion device according to the fifth embodiment of the present invention, when viewed from the thickness direction of the housing, the porous sheet is exposed at the portion where the wick overlaps the evaporator and the liquid channel.

FIG. 13 is a plan view schematically showing an example of a heat diffusion device according to the fifth embodiment of the invention. 14 is a cross-sectional view of the heat spreading device shown in FIG. 13 along line XIV-XIV. 15 is a cross-sectional view of the heat spreading device shown in FIG. 13 along line XV-XV.

In the vapor chamber (heat diffusion device) 5 shown in FIG. 13, when viewed from the thickness direction Z of the housing 10, the wick 30 overlaps the evaporation part EP and the liquid flow path 40 as shown in FIGS. Part of the porous sheet 31 is exposed. That is, when viewed from the thickness direction Z of the housing 10 , the wick 30 does not include the porous sintered body 32 in the portion where the wick 30 overlaps the evaporator EP and the liquid flow path 40 . On the other hand, in portions other than the evaporation part EP, as in the vapor chamber 1 and the like shown in FIG. and a porous sintered body 32 provided thereon.

In the vapor chamber 5 shown in FIG. 13, by exposing the porous sheet 31 in the evaporation part EP, the evaporation heat resistance in the evaporation part EP can be lowered.

[Other embodiments]
The heat diffusion device of the present invention is not limited to the above-described embodiments, and various applications and modifications can be made within the scope of the present invention regarding the structure of the heat diffusion device, manufacturing conditions, and the like.

In the heat diffusion device of the present invention, one wick may be arranged, or a plurality of wicks may be arranged. When a plurality of wicks are arranged, it is preferable that the plurality of wicks extend so as to be spaced apart and parallel to each other in plan view from the thickness direction.

FIG. 16 is a plan view schematically showing an example of the internal structure of a heat diffusion device in which a plurality of wicks are arranged.

A plurality of wicks 30 are arranged in the vapor chamber (heat diffusion device) 6 shown in FIG. Other configurations are the same as those of the vapor chamber 1 . Although four wicks 30 are shown in FIG. 16, the number of wicks 30 is not particularly limited as long as it is two or more.

In plan view from the thickness direction Z, the plurality of wicks 30 extend parallel to each other at intervals. These wicks 30 are preferably arranged so as to be concentrated in the evaporating section EP, as shown in FIG. By collecting the wick 30 in the evaporator EP, the working medium can be circulated over a short distance.

As shown in FIG. 16, it is preferable that first steam flow paths 51 are formed between adjacent wicks 30 . In this case, between the outermost one of the plurality of wicks 30 (the left wick 30 in FIG. 16) and the housing 10, a first vapor channel 51 wider than the first steam flow path 51 is provided. It is preferable that two steam flow paths 52 are formed. Further, a third steam channel 53 wider than the first steam channel 51 is formed between the other outermost wick 30 (the right wick 30 in FIG. 16) and the housing 10. preferably.

If the plurality of wicks 30 are unevenly distributed in one part, the steam of the working medium does not pass through that part, so the uniform heating performance of the vapor chamber as a whole decreases. Therefore, by providing a gap between the wicks 30 and using the gap as a steam flow path, the uniform heating performance can be improved. As a result, it is possible to obtain a vapor chamber which is excellent in liquid circulation and vapor circulation, and which has high liquid transportation capacity and heat soaking performance.

The materials of the wicks 30 may be the same or different.

The thickness of each wick 30 may be the same or different.

In the heat diffusion device of the present invention, the housing may have one evaporator or may have a plurality of evaporators. That is, one heat source may be arranged on the outer wall surface of the housing, or a plurality of heat sources may be arranged. The number of evaporators and heat sources is not particularly limited.

FIG. 17 is a plan view schematically showing an example of the internal structure of a heat diffusion device whose housing has a plurality of evaporators. FIG. 18 is a plan view schematically showing another example of the internal structure of a heat diffusion device whose housing has a plurality of evaporators.

In the vapor chamber (heat diffusion device) 6a shown in FIG. 17, two wicks 30 are arranged, and the evaporator EP is provided at the end of each wick 30. In the vapor chamber (heat diffusion device) 6b shown in FIG. 18, three wicks 30 are arranged, and an evaporator EP is provided at the end of each wick 30. As shown in FIG.

In the heat diffusion device of the present invention, the evaporator may be provided at the end of the housing or may be provided at the center of the housing.

In the heat diffusion device of the present invention, when the housing is composed of the first sheet and the second sheet, the first sheet and the second sheet may be overlapped so that the edges are aligned, or the edges may overlap. may be shifted and overlapped.

In the heat diffusion device of the present invention, when the housing is composed of the first sheet and the second sheet, the material of the first sheet and the material of the second sheet may be different. For example, by using a high-strength material for the first sheet, the stress applied to the housing can be dispersed. Also, by using different materials for the two sheets, one sheet can have one function and the other sheet can have another function. The above functions are not particularly limited, but include, for example, a heat conduction function, an electromagnetic wave shielding function, and the like.

The heat diffusion device of the present invention may further include a wick that does not contain a porous sheet or a wick that does not contain a porous sintered body. Also, the heat spreading device of the present invention may further comprise a wick that does not form a liquid flow path. In that case, the wick is not particularly limited as long as it has a capillary structure capable of moving the working medium by capillary force. The capillary structure of the wick may be any known structure used in conventional heat spreading devices. The capillary structure includes fine structures having unevenness such as pores, grooves, and projections, such as porous structures, fiber structures, groove structures, and network structures.

The heat diffusion device of the present invention can be mounted on electronic equipment for the purpose of heat dissipation. Therefore, an electronic device including the heat diffusion device of the present invention is also one aspect of the present invention. Examples of the electronic device of the present invention include smart phones, tablet terminals, notebook computers, game machines, wearable devices, and the like. As described above, the heat diffusion device of the present invention can operate independently without requiring external power, and can diffuse heat two-dimensionally and at high speed by utilizing the latent heat of vaporization and latent heat of condensation of the working medium. Therefore, an electronic device equipped with the heat diffusion device of the present invention can effectively dissipate heat in a limited space inside the electronic device.

The heat diffusion device of the present invention can be used for a wide range of applications in fields such as personal digital assistants. For example, it can be used to lower the temperature of a heat source such as a CPU and extend the operating time of electronic equipment, and can be used in smartphones, tablet terminals, laptop computers, and the like.

1, 1a, 1b, 2, 2a, 3, 4, 5, 6, 6a, 6b vapor chamber (heat diffusion device)
10 housing 11 first sheet 11a first inner wall surface 12 second sheet 12a second inner wall surface 20 working medium 30 wick 31 porous sheet 32 porous sintered body 40 liquid channel 41 upper surface of liquid channel 42 liquid channel 50 steam channel 51 first steam channel 52 second steam channel 53 third steam channel 60 support 61 support 62 support wall EP evaporator HS heat source X width direction Y length direction Z thickness direction

Claims

a housing;
a working medium enclosed in the internal space of the housing;
a wick disposed in the inner space of the housing and forming at least a part of the surface of the liquid flow path of the working medium;
the liquid channel has a top surface away from the inner wall surface of the housing and a side surface continuous with the top surface and in contact with the inner wall surface of the housing;
The wick includes a porous sheet and a porous sintered body provided on at least a portion of the porous sheet,
A heat diffusion device, wherein the minimum pore size of the porous sheet is larger than the maximum pore size of the porous sintered body.
The heat diffusion device according to claim 1, wherein the porous sheet is an etched perforated plate.
The heat diffusion device according to claim 1, wherein the porous sheet is a mesh.
a housing;
a working medium enclosed in the internal space of the housing;
a wick disposed in the inner space of the housing and forming at least a part of the surface of the liquid flow path of the working medium;
the liquid channel has a top surface away from the inner wall surface of the housing and a side surface continuous with the top surface and in contact with the inner wall surface of the housing;
The wick includes a porous sheet and a porous sintered body provided on at least a portion of the porous sheet,
The heat diffusion device, wherein the porous sheet is a non-woven fabric.
The thermal diffusion device according to any one of claims 1 to 4, wherein the porous sheet is in contact with the upper surface of the liquid channel.
The thermal diffusion device according to any one of claims 1 to 4, wherein the porous sintered body is in contact with the upper surface of the liquid channel.
The thermal diffusion device according to any one of claims 1 to 6, wherein the porous sintered body is in contact with the side surface of the liquid channel.
The thermal diffusion device according to any one of claims 1 to 7, further comprising a support arranged in the internal space of the housing along the extending direction of the liquid channel and supporting the wick.
The thermal diffusion device according to claim 8, wherein the support is composed of a plurality of struts arranged at intervals along the extending direction of the liquid channel.
The thermal diffusion device according to claim 8, wherein the support body is composed of a support wall forming a side surface of the liquid channel along the extending direction of the liquid channel.
the housing has an evaporator in its internal space,
11. The porous sheet according to any one of claims 1 to 10, wherein when viewed from the thickness direction of the housing, the porous sheet is exposed at a portion where the wick overlaps the evaporator and the liquid channel. heat spreading device.
An electronic device comprising the heat diffusion device according to any one of claims 1 to 11.