JP7743889B2 - Vapor chambers and electronic devices - Google Patents

Description

This disclosure relates to a vapor chamber that transfers heat by circulating a working fluid sealed in an enclosed space while undergoing a phase change.

The amount of heat generated by electronic components such as central processing units (CPUs) found in personal computers and mobile devices such as mobile phones and tablet computers tends to increase as information processing capabilities improve, making cooling technology important. Heat pipes are a well-known means of cooling. These use a working fluid sealed inside the pipe to transport and diffuse heat from a heat source to other parts, thereby cooling the heat source.

On the other hand, in recent years, there has been a remarkable trend toward thinner devices, particularly mobile devices, and there is a need for cooling means that are thinner than conventional heat pipes. In response to this, vapor chambers have been proposed, such as those described in Patent Document 1.

A vapor chamber is a device that applies the concept of heat transport using a heat pipe to a flat plate-shaped component. In other words, a vapor chamber contains a working fluid sealed between opposing flat plates, and heat is transported by this working fluid circulating while undergoing phase changes, transporting and diffusing heat from the heat source to cool it.

More specifically, a vapor channel and a condensate channel are provided between the opposing flat plates of the vapor chamber, and a working fluid is sealed in these channels. When the vapor chamber is placed next to a heat source, the working fluid near the heat source receives heat from the heat source and evaporates, becoming a gas (vapor) that travels down the vapor channel. This allows heat from the heat source to be smoothly transported to a location away from the heat source, resulting in cooling of the heat source.
The gaseous working fluid that transports heat from the heat source moves to a position away from the heat source, where it is cooled and condensed as heat is absorbed by the surroundings, changing into a liquid state. The liquid working fluid passes through the condensate flow path, returns to the heat source, and absorbs heat from the heat source again, evaporating and changing into a gaseous state.
By circulating the heat generated from the heat source as described above, the heat is transported to a location away from the heat source, and the heat source is cooled.

Patent Document 1 discloses a vapor chamber formed by joining two flat plates as described above to form a vapor flow path and a condensate flow path.

Japanese Patent Application Laid-Open No. 2009-076650

The present disclosure aims to provide a vapor chamber that can prevent breakage of the walls between flow channels while increasing productivity. It also provides an electronic device equipped with this vapor chamber and a sheet for the vapor chamber.

After extensive research, the inventors discovered that fractures in the walls between flow channels originate from grain boundaries, and have developed a structure that can prevent fractures in the walls between flow channels even when diffusion bonding is performed under highly productive conditions that prevent the bonding interface from disappearing.

This application discloses a vapor chamber made of a laminate of multiple sheets, having a sealed space filled with a working fluid. The sealed space has a capillary structure through which the working fluid in a liquid state flows, and a vapor flow path through which the working fluid in a gaseous state flows. In a cross-sectional view, the length of the sheet bonding interface in the wall portion located between the capillary structure and the vapor flow path is longer than the minimum width of the wall portion, and the minimum width of the wall portion is 10 μm or more and 400 μm or less.

The present application also discloses a vapor chamber made of a laminate of multiple sheets, having a sealed space filled with a working fluid, wherein the sealed space is provided with a first flow path through which the working fluid in a gaseous state flows and a second flow path through which the working fluid in a liquid state flows, and wherein, in a cross-sectional view, the length of the sheet bonding interface in a wall portion located between the first flow path and the second flow path is longer than the minimum width of the wall portion, and the minimum width of the wall portion is 10 μm or more and 400 μm or less.

The present application also discloses a vapor chamber which is a laminate of multiple sheets and has a sealed space in which a working fluid is sealed, the sealed space having multiple first flow paths and a second flow path provided between adjacent first flow paths, wherein, when the average flow path cross-sectional area of two adjacent first flow paths is A _g and the average flow path cross-sectional area of multiple second flow paths arranged between adjacent first flow paths is A _l , A _l is at least partially 0.5 times A _g or less, and in a cross-sectional view, the length of the joining interface of the sheets in a wall portion arranged between the first flow paths and the second flow paths is longer than the minimum width of the wall portion, and the minimum width of the wall portion is 10 μm or more and 400 μm or less.

In the vapor chamber, the bonding interface may be curved.

In the vapor chamber, the bonding interface may be asymmetric in the width direction of the wall.

The present application also discloses an electronic device comprising a housing, an electronic component disposed inside the housing, and the vapor chamber described above disposed in the electronic component.

The vapor chamber disclosed herein can relax the conditions for diffusion bonding, shorten the time required, and increase productivity.

FIG. 1 is a perspective view of a vapor chamber. FIG. 2 is an exploded perspective view of the vapor chamber. FIG. 3 is a perspective view of the first sheet. FIG. 4 is a plan view of the first sheet. FIG. 5 shows a cross section of the first sheet. FIG. 6 shows another cross section of the first sheet. FIG. 7 shows another cross section of the first sheet. FIG. 8 is a partially enlarged plan view of the outer peripheral liquid flow path portion. FIG. 9 is an enlarged view of a cross section of one liquid flow channel. FIG. 10 is an enlarged cross-sectional view of one of the protrusions. FIG. 11 is a partially enlarged plan view of another example of the outer peripheral liquid flow path portion. FIG. 12 is a partially enlarged plan view of another example of the outer peripheral liquid flow path portion. FIG. 13 is a partially enlarged plan view of another example of the outer peripheral liquid flow path portion. FIG. 14 is a partially enlarged plan view of another example of the outer peripheral liquid flow path portion. FIG. 15 is a cross section focusing on one of the inner liquid flow path portions. FIG. 16 is an enlarged view of a cross section of one liquid flow channel. FIG. 17 is a diagram focusing on one protrusion. FIG. 18 is a partially enlarged plan view of the inner liquid flow path section. FIG. 19 is a perspective view of the second sheet. FIG. 20 is a plan view of the second sheet. FIG. 21 shows a cross section of the second sheet. FIG. 22 shows a cross section of the second sheet. FIG. 23 is a cross section of the vapor chamber. FIG. 24 is an enlarged view of a part of FIG. FIG. 25 is another cross-section of the vapor chamber. FIG. 26 is an enlarged view of the vicinity of one condensate flow path. FIG. 27 is an enlarged view of the vicinity of one wall portion. FIG. 28 is a diagram illustrating an example of the boundary shape. FIG. 29 is a diagram illustrating an example of the boundary shape. FIG. 30 is a diagram illustrating an example of the boundary shape. FIG. 31 is a diagram illustrating an example of the boundary shape. FIG. 32 is a diagram illustrating an example of the boundary shape. FIG. 33 is a diagram illustrating an electronic device. FIG. 34 is a diagram illustrating the flow of the working fluid. FIG. 35 is a diagram illustrating a vapor chamber according to another embodiment. FIG. 36 is a diagram illustrating a vapor chamber according to another embodiment.

The present disclosure will be described below based on the embodiments shown in the drawings. Note that in the drawings below, the size and proportions of components may be altered or exaggerated for clarity. Furthermore, for clarity, parts not required for explanation and repeated reference numerals may be omitted.

Figure 1 shows an external perspective view of one embodiment of the vapor chamber 1, and Figure 2 shows an exploded perspective view of the vapor chamber 1. For convenience, these figures and the figures shown below also include arrows (x, y, z) indicating directions as needed. Here, the xy in-plane direction is the plate surface direction of the flat vapor chamber 1, and the z direction is the thickness direction.

As can be seen from Figures 1 and 2, the vapor chamber 1 has a first sheet 10 and a second sheet 20. As will be explained later, the first sheet 10 and the second sheet 20 are stacked and diffusion bonded together to form a sealed space 2 between the first sheet 10 and the second sheet 20 (see, for example, Figure 23), and a working fluid is sealed in this sealed space 2.

In this embodiment, the first sheet 10 is a sheet-like member as a whole. Fig. 3 shows a perspective view of the first sheet 10 as seen from the inner surface 10a side, and Fig. 4 shows a plan view of the first sheet 10 as seen from the inner surface 10a side. Fig. 5 shows a cross section of the first sheet 10 when cut along III-III in Fig. 4.
The first sheet 10 has an inner surface 10a, an outer surface 10b opposite the inner surface 10a, and a side surface 10c connecting the inner surface 10a and the outer surface 10b to form a thickness, and a pattern for a flow path through which the working fluid returns is formed on the inner surface 10a side. As will be described later, the inner surface 10a of the first sheet 10 and the inner surface 20a of the second sheet 20 are overlapped so as to face each other to form a hollow portion, and the working fluid is sealed in this hollow portion to form the sealed space 2.

The first sheet 10 includes a main body 11 and an injection portion 12. The main body 11 is a sheet-like body that forms a region where the working fluid circulates, and in this embodiment, is a rectangle with arc-shaped (so-called R) corners in a plan view.
However, the main body 11 of the first sheet 10 may be rectangular as in this embodiment, or may be circular, elliptical, triangular, or other polygonal, or may have a shape with a bent portion, such as an L-shape, a T-shape, or a crank shape, etc. Also, it may have a shape that combines at least two of these shapes.

The injection section 12 is a section where the working fluid is injected into the hollow section formed by the first sheet 10 and the second sheet 20 to create the sealed space 2 (see, for example, Figure 23). In this embodiment, it is a sheet-like shape that is rectangular in plan view and protrudes from one side of the main body 11, which is rectangular in plan view.

The thickness of the first sheet 10 is not particularly limited, but is preferably 1.0 mm or less, and may be 0.75 mm or less, or 0.5 mm or less. On the other hand, the thickness is preferably 0.02 mm or more, and may be 0.05 mm or more, or may be 0.1 mm or more. This thickness range may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, this thickness range may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.
This increases the number of situations in which it can be used as a thin vapor chamber.

The material constituting the first sheet 10 is not particularly limited, but is preferably a metal with high thermal conductivity, such as copper or a copper alloy.
However, the material does not necessarily have to be a metal, and may be, for example, a ceramic such as AlN, Si ₃ N ₄ or Al ₂ O ₃ , or a resin such as polyimide or epoxy.
Furthermore, a sheet may be used in which two or more types of materials are laminated within one sheet, or different materials may be used depending on the location.

A structure for circulating the working fluid is formed on the inner surface 10a of the main body 11. Specifically, the inner surface 10a of the main body 11 is provided with an outer periphery joint 13, an outer periphery liquid flow path section 14, an inner liquid flow path section 15, a steam flow path groove 16, and a steam flow path connecting groove 17.

The outer peripheral bonding portion 13 is a surface formed on the inner surface 10a side of the main body 11 along the outer periphery of the main body 11. This outer peripheral bonding portion 13 overlaps and is diffusion bonded to the outer peripheral bonding portion 23 of the second sheet 20, thereby forming a hollow space between the first sheet 10 and the second sheet 20, and a working fluid is sealed in this hollow space to form the sealed space 2.
The width of the outer peripheral joint portion 13 indicated by A in Figures 4 and 5 (the size in the direction perpendicular to the extension direction of the outer peripheral joint portion 13, i.e., the width at the joint surface with the second sheet 20) can be set appropriately as needed, but this width A is preferably 3 mm or less, and may be 2.5 mm or less, or may be 2.0 mm or less. If the width A is greater than 3 mm, the internal volume of the sealed space may be reduced, and there is a risk that the steam flow path and the condensate flow path may not be sufficiently secured. On the other hand, the width A is preferably 0.2 mm or more, and may be 0.6 mm or more, or may be 0.8 mm or more. If the width A is less than 0.2 mm, there is a risk that the joint area may be insufficient if misalignment occurs during joining of the first sheet and the second sheet. The range of the width A may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of the width A may be determined by combining any two of the multiple upper limit candidate values or any two of the multiple lower limit candidate values.

In addition, holes 13a that penetrate the main body 11 in the thickness direction (z direction) are provided at the four corners of the outer peripheral joint 13. These holes 13a function as positioning means when overlapping with the second sheet 20.

The peripheral liquid flow path section 14 functions as a liquid flow path section and constitutes part of the condensed liquid flow path 3, which is the second flow path through which the working fluid passes when condensed and liquefied. Figure 6 shows the portion indicated by arrow IVa in Figure 5, and Figure 7 shows a cross section of the portion cut along line IVb-IVb in Figure 4. Both figures show the cross-sectional shape of the peripheral liquid flow path section 14. Figure 8 also shows an enlarged plan view of the peripheral liquid flow path section 14 as seen from the direction indicated by arrow V in Figure 6.

As can be seen from these figures, the peripheral liquid flow path section 14 is formed on the inner surface 10a of the main body 11, along the inside of the peripheral joint 13, and along the outer periphery of the sealed space 2. Furthermore, the peripheral liquid flow path section 14 is formed with multiple liquid flow path grooves 14a that extend along the outer periphery of the main body 11, and the multiple liquid flow path grooves 14a are arranged at predetermined intervals in a direction different from the direction in which the liquid flow path grooves 14a extend. Therefore, as can be seen from Figures 6 and 7, the peripheral liquid flow path section 14 has a repeated unevenness on the inner surface 10a side in its cross section, with the liquid flow path grooves 14a being recesses and the protrusions 14b between the liquid flow path grooves 14a.

By providing multiple liquid flow path grooves 14a in this way, the depth and width of each liquid flow path groove 14a can be reduced, reducing the cross-sectional area of the condensate flow path 3 (see Figure 24, etc.), which is the second flow path, and making use of the strong capillary force. On the other hand, by providing multiple liquid flow path grooves 14a, the combined cross-sectional area of the condensate flow path 3 as a whole can be ensured to be an appropriate size, allowing the required flow rate of condensate to flow.

Here, since the liquid flow path groove 14a is a groove, its cross-sectional shape has a bottom provided on the outer surface 10b side and an opening provided on the inner surface 10a side opposite to the bottom. Figure 9 shows an enlarged view of one liquid flow path groove 14a in Figure 6.
In this embodiment, the liquid flow path groove 14a has a semi-elliptical cross section, but the cross-sectional shape is not limited to a semi-elliptical shape and may be a circle, a quadrangle such as a rectangle, a square, or a trapezoid, or any other polygon, or any other geometric shape, or a shape that is a combination of any of these.

Figure 10 shows an enlarged view of one of the convex portions 14b in Figure 6. In this embodiment, the convex portions 14b are convex portions formed between adjacent liquid flow path grooves 14a and between the steam flow path groove 16 and the liquid flow path groove 14a, and their tops are flat before bonding to the second sheet 20. These convex portions 14b form the wall portions 3a of the condensate flow path 3, which is the adjacent second flow path, and the wall portion 3a between the steam flow path 4 and the condensate flow path 3.

8, adjacent liquid flow path grooves 14a in the outer peripheral liquid flow path section 14 are connected to each other by communication openings 14c at predetermined intervals, which promotes equalization of the amount of condensed liquid among the plurality of liquid flow path grooves 14a, allowing the condensed liquid to flow efficiently and enabling smooth reflux of the working fluid.
In this embodiment, the communicating openings 14c are arranged so as to face each other at the same position in the extension direction of one liquid flow path groove 14a, with the groove in between, as shown in Fig. 8. However, this is not limited to this, and the communicating openings 14c may be arranged at different positions in the extension direction of one liquid flow path groove 14a, as shown in Fig. 11, for example. In other words, the protrusions 14b and the communicating openings 14c may be arranged alternately in a direction perpendicular to the extension direction of the liquid flow path groove 14a.

Other configurations are also possible, for example, as shown in Figures 12 to 14. Figures 12 to 14 are views showing one condensate flow path 14a, two convex portions 14b sandwiching it, and one communication opening 14c provided in each convex portion 14b, from the same perspective as Figure 8. In all of these, the shape of the convex portion 14b from that perspective (plan view) is different from the example in Figure 8.
That is, in the protrusion 14b shown in Fig. 8, the width at the end where the communicating opening 14c is formed is constant and the same as that at other portions. In contrast, in the protrusions 14b shaped as shown in Figs. 12 to 14, the width at the end where the communicating opening 14c is formed is formed to be smaller than the maximum width of the protrusion 14b. More specifically, the example in Fig. 12 shows an example in which the corners at the end are arc-shaped and rounded, thereby reducing the width of the end; Fig. 13 shows an example in which the end is semicircular, thereby reducing the width; and Fig. 14 shows an example in which the end is tapered to a sharp point.

As shown in Figures 12 to 14, the width of the end of the convex portion 14b where the communication opening 14c is formed is formed to be smaller than the maximum width of the convex portion 14b, which makes it easier for the working fluid to move through the communication opening 14c and to move to the adjacent condensate flow path 3.

The peripheral liquid flow path section 14 having the above-described configuration preferably further has the following configuration.
The width of the outer peripheral liquid flow path section 14, indicated by B in FIGS. 4 to 7 (the size in the direction in which the liquid flow path sections 14a are arranged, at the bonding surface with the second sheet 20), can be set appropriately based on the size of the entire vapor chamber, etc., but width B is preferably 3.0 mm or less, and may be 1.5 mm or less, or 1.0 mm or less. If width B exceeds 2 mm, there is a risk that sufficient space will not be provided for the inner liquid flow path and vapor flow path. On the other hand, width B is preferably 0.1 mm or more, and may be 0.2 mm or more, or 0.4 mm or more. If width B is less than 0.1 mm, there is a risk that a sufficient amount of liquid will not be able to circulate outside. The range of width B may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of width B may be determined by combining any two of the multiple upper limit candidate values or any two of the multiple lower limit candidate values.
The width B may be the same as the width S (see FIG. 21) of the outer peripheral liquid flow path portion 24 of the second sheet 20, or may be larger or smaller. In this embodiment, they are the same.

Regarding the liquid flow path grooves 14a, the groove width (the size in the direction in which the liquid flow path grooves 14a are arranged, the width at the opening surface of the groove) indicated by _C1 in Figures 6, 8, and 9 is preferably 1000 μm or less, and may be 500 μm or less, or may be 200 μm or less. On the other hand, the width _C1 is preferably 20 μm or more, and may be 45 μm or more, or may be 60 μm or more. The range of the width _C1 may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of the width _C1 may be determined by combining any two of the multiple upper limit candidate values, or by combining any two of the multiple lower limit candidate values.
Furthermore, the groove depth indicated by D in Figures 6, 7, and 9 is preferably 200 μm or less, and may be 150 μm or less, or 100 μm or less. On the other hand, the depth D is preferably 5 μm or more, and may be 10 μm or more, or may be 20 μm or more. The range of the depth D may be determined by a combination of any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. Furthermore, the range of the depth D may be determined by a combination of any two of the plurality of upper limit candidate values, or a combination of any two of the plurality of lower limit candidate values.
By configuring as above, the capillary force of the condensate flow path necessary for reflux can be exerted more strongly.

From the viewpoint of exerting a stronger capillary force in the condensate flow path, the aspect ratio (length-to-length ratio) of the flow path cross section, which is expressed by the value obtained by dividing the groove width _C1 by the depth D, is preferably greater than 1.0. This ratio may be 1.5 or greater, or may be 2.0 or greater. Alternatively, the aspect ratio may be less than 1.0. This ratio may be 0.75 or less, or may be 0.5 or less.
Among these, from the viewpoint of manufacturing, it is preferable that _C1 is larger than D, and from this viewpoint, it is preferable that the aspect ratio is larger than 1.3.

Furthermore, the pitch between adjacent liquid flow path grooves 14a among the plurality of liquid flow path grooves 14a is preferably 1100 μm or less, and may be 550 μm or less, or 220 μm or less. On the other hand, the pitch is preferably 30 μm or more, and may be 55 μm or more, or may be 70 μm or more. This pitch range may be determined by combining any one of the plurality of upper limit candidate values and any one of the plurality of lower limit candidate values. Furthermore, the pitch range may be determined by combining any two of the plurality of upper limit candidate values, or any two of the plurality of lower limit candidate values.
This makes it possible to increase the density of the condensate flow path while suppressing the condensate flow path from being crushed due to deformation during joining or assembly.

Regarding the convex portions 14b, the width of the convex portions 14b (the size in the direction perpendicular to the direction in which the convex portions extend, that is, the direction in which the multiple convex portions 14b are arranged) indicated by _C2 in Figures 6, 8, and 10 is preferably 400 μm or less, and may be 300 μm or less, or may be 200 μm or less. On the other hand, the width _C2 is preferably 10 μm or more, and may be 20 μm or more, or may be 30 μm or more. The range of this width _C2 may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of width _C2 may be determined by combining any two of the multiple upper limit candidate values, or by combining any two of the multiple lower limit candidate values.

For the communication opening 14c, the size of the opening along the extension direction of the liquid flow path groove 14a, indicated by E in Figure 8, is preferably 1100 μm or less, and may be 550 μm or less, or 220 μm or less. On the other hand, the size E is preferably 30 μm or more, and may be 55 μm or more, or 70 μm or more. The range of size E may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of size E may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.

Furthermore, the pitch between adjacent communication openings 14c in the direction in which the liquid flow path groove 14a extends, indicated by F in Figure 8, is preferably 2700 μm or less, and may be 1800 μm or less, or 900 μm or less. On the other hand, this pitch F is preferably 60 μm or more, and may be 110 μm or more, or 140 μm or more. This pitch range may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the pitch range may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.

Returning to Figures 3 to 5, the inner liquid flow path section 15 will now be described. The inner liquid flow path section 15 also functions as a liquid flow path section, and is a part that constitutes part of the condensed liquid flow path 3, which is the second flow path through which the working fluid passes when condensed and liquefied. Figure 15 shows the portion indicated by arrow VIII in Figure 5. This figure also shows the cross-sectional shape of the inner liquid flow path section 15. Additionally, Figure 18 shows an enlarged plan view of the inner liquid flow path section 15 as seen from the direction indicated by arrow X in Figure 15.

As can be seen from these figures, the inner liquid flow path section 15 is formed on the inner surface 10a of the main body 11, inside the annular ring of the outer peripheral liquid flow path section 14. As can be seen from Figures 3 and 4, the inner liquid flow path section 15 in this embodiment is a wall that is rectangular in plan view of the main body 11 and extends in a direction parallel to the long side (x direction), and multiple (three in this embodiment) inner liquid flow path sections 15 are arranged at predetermined intervals in a direction parallel to the short side (y direction).
Each inner liquid flow path section 15 is formed with liquid flow path grooves 15a that are grooves parallel to the direction in which the inner liquid flow path section 15 extends, and multiple liquid flow path grooves 15a are arranged at predetermined intervals in a direction different from the direction in which the liquid flow path grooves 15a extend. Therefore, as can be seen from Figures 5 and 15, in the cross section of the inner liquid flow path section 15, on the inner surface 10a side, convex ridges formed by the liquid flow path grooves 15a that are recesses and convex portions 15b that are between the liquid flow path grooves 15a are formed in a repeated irregular pattern.

By providing multiple liquid flow path grooves 15a in this way, the depth and width of each liquid flow path groove 15a can be reduced, reducing the cross-sectional area of the condensate flow path 3 (see Figure 24, etc.) serving as the second flow path, making it possible to utilize a strong capillary force. Furthermore, by forming even smaller grooves on the inner surface of the condensate flow path 3, even stronger capillary force can be obtained. Meanwhile, by providing multiple liquid flow path grooves 15a, the combined cross-sectional area of the condensate flow path 3 as a whole can be ensured to be an appropriate size, allowing the required flow rate of condensate to flow.

Here, since the liquid flow path groove 15a is a groove, its cross-sectional shape has a bottom provided on the outer surface 10b side and an opening provided on the inner surface 10a side at a position opposite to the bottom. Figure 16 shows an enlarged view of one liquid flow path groove 15a in Figure 15.
In this embodiment, the liquid flow path groove 15a has a semi-elliptical cross section, but the cross-sectional shape is not limited to a semi-elliptical shape and may be a circle, a quadrangle such as a rectangle, a square, or a trapezoid, or any other polygon, or any other geometric shape, or a shape that combines two or more of these.

Figure 17 shows an enlarged view of one of the protrusions 15b in Figure 15. In this embodiment, the protrusions 15b are protrusions formed between adjacent liquid flow path grooves 15a and between the steam flow path groove 16 and the liquid flow path groove 15a, and their tops are flat before bonding to the second sheet 20. These protrusions 15b form the wall portions 3a of adjacent condensate flow paths 3 and the wall portion 3a between the steam flow path 4 and the condensate flow path 3.

18, adjacent liquid flow grooves 15a are connected to each other by communication openings 15c at predetermined intervals, which promotes equalization of the amount of condensed liquid among the plurality of liquid flow grooves 15a and allows the condensed liquid to flow efficiently, thereby enabling smooth reflux of the working fluid.
As with the communicating openings 14c, the communicating openings 15c may also be arranged such that the protrusions 15b and the communicating openings 15c are alternately arranged in a direction perpendicular to the direction in which the liquid flow path grooves 15a extend, following the example shown in Fig. 11. Alternatively, the communicating openings 15c and the protrusions 15b may be shaped as shown in Figs. 12 to 14.

The inner liquid flow path section 15 having the above-described configuration preferably further has the following configuration.
The width of the inner liquid flow path section 15 indicated by G in Figures 4, 5, and 15 (the size in the direction in which the inner liquid flow path section 15 and the vapor flow path grooves 16 are arranged, and the width at the bonding surface with the second sheet 20) is preferably 3000 µm or less, and may be 1500 µm or less, or 1000 µm or less. On the other hand, this width G is preferably 100 µm or more, and may be 200 µm or more, or may be 400 µm or more. The range of this width G may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of width G may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.
The width G may be the same as or different from the width T (see FIG. 21) of the inner liquid flow path section 25 of the second sheet 20. In this embodiment, they are the same.

The pitch between the multiple inner liquid flow path sections 15 is preferably 4000 μm or less, but may be 3000 μm or less, or may be 2000 μm or less. On the other hand, the pitch is preferably 200 μm or more, but may be 400 μm or more, or may be 800 μm or more. The pitch range may be determined by combining any one of the multiple upper limit candidate values and any one of the multiple lower limit candidate values. The pitch range may also be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.
This reduces the flow resistance of the steam flow path, and allows for a good balance between the movement of steam and the return of condensed liquid.

Regarding the liquid flow path grooves 15a, the groove width (the size in the direction in which the liquid flow path grooves 15a are arranged, and the width at the opening surface of the groove) indicated by _H1 in Figures 17 and 18 is preferably 1000 μm or less, and may be 500 μm or less, or may be 200 μm or less. On the other hand, this width _H1 is preferably 20 μm or more, and may be 45 μm or more, or may be 60 μm or more. The range of this width _H1 may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of width _H1 may be determined by combining any two of the multiple upper limit candidate values, or by combining any two of the multiple lower limit candidate values.
Furthermore, the groove depth indicated by J in Figures 15 and 16 is preferably 200 μm or less, but may be 150 μm or less, or may be 100 μm or less. On the other hand, this depth J is preferably 5 μm or more, but may be 10 μm or more, or may be 20 μm or more. The range of this depth J may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of depth J may be determined by combining any two of the multiple upper limit candidate values, or by combining any two of the multiple lower limit candidate values.
This allows the capillary force of the condensate flow path, which is necessary for reflux, to be exerted strongly.

From the viewpoint of exerting a stronger capillary force in the flow channel, the aspect ratio (length-to-length ratio) of the flow channel cross section, which is expressed by the value obtained by dividing the groove width H1 by the depth J, is preferably greater than 1.0. It may be 1.5 or greater, or 2.0 or greater. Alternatively, it may be less than 1.0, or may be 0.75 or less, or 0.5 or less.
Among these, from the viewpoint of manufacturing, it is preferable that the groove width _H1 is larger than the depth J, and from this viewpoint, it is preferable that the aspect ratio is larger than 1.3.

Furthermore, the pitch between adjacent liquid flow path grooves 15a among the plurality of liquid flow path grooves 15a is preferably 1100 μm or less, and may be 550 μm or less, or may be 220 μm or less. On the other hand, this pitch is preferably 30 μm or more, and may be 55 μm or more, or may be 70 μm or more. This pitch range may be determined by combining any one of the plurality of upper limit candidate values and any one of the plurality of lower limit candidate values. Furthermore, the pitch range may be determined by combining any two of the plurality of upper limit candidate values, or any two of the plurality of lower limit candidate values.
This makes it possible to increase the density of the condensate flow path while suppressing deformation and collapse of the flow path during joining or assembly.

Furthermore, with regard to the communication opening 15c, the size of the opening along the extension direction of the liquid flow path groove 15a, indicated by K in Figure 18, is preferably 1100 μm or less, and may be 550 μm or less, or 220 μm or less. On the other hand, this size K is preferably 30 μm or more, and may be 55 μm or more, or 70 μm or more. The range of this size K may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, the range of size K may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.

Furthermore, the pitch between adjacent communication openings 15c in the direction in which the liquid flow path groove 15a extends, indicated by L in FIG. 18, is preferably 2700 μm or less, and may be 1800 μm or less, or may be 900 μm or less. On the other hand, this pitch L is preferably 60 μm or more, and may be 110 μm or more, or may be 140 μm or more. This pitch range may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, this pitch range may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.

In the above-described embodiment, the liquid flow path grooves 14a and 15a are arranged parallel to each other and spaced apart at equal intervals, but this is not limited to this. As long as capillary action can be achieved, the pitch between the grooves may vary, and the grooves may not be parallel to each other.

Next, we will explain the steam flow channel groove 16. The steam flow channel groove 16 is the section through which the vaporized steam generated when the working fluid evaporates, and constitutes part of the steam flow channel 4 (see Figure 23, etc.), which is the first flow channel. Figure 4 shows the shape of the steam flow channel groove 16 in a plan view, and Figure 5 shows the cross-sectional shape of the steam flow channel groove 16.

As can be seen from these figures, the steam flow path grooves 16 are grooves formed on the inner surface 10a of the main body 11, inside the annular ring of the outer peripheral liquid flow path section 14. Specifically, the steam flow path grooves 16 in this embodiment are formed between adjacent inner liquid flow path sections 15 and between the outer peripheral liquid flow path section 14 and the inner liquid flow path section 15, and are rectangular in plan view of the main body 11, extending in a direction parallel to the long sides (x direction). A plurality of steam flow path grooves 16 (four in this embodiment) are arranged in a direction parallel to the short sides (y direction). Therefore, as can be seen from Figure 5, the first sheet 10 has a shape in the y direction in which projections and depressions are repeated, with the projections of the outer peripheral liquid flow path section 14 and the inner liquid flow path section 15 and the steam flow path grooves 16 as depressions.
Here, since the steam flow channel groove 16 is a groove, its cross-sectional shape has a bottom portion on the outer surface 10b side and an opening on the inner surface 10a side opposite to the bottom portion.

The steam flow channel groove 16 having such a configuration preferably further has the following configuration.
The width of the vapor flow path groove 16, indicated by M in FIGS. 4 and 5 (the size in the direction in which the inner liquid flow path section 15 and the vapor flow path groove 16 are arranged, and the width at the groove opening surface) is at least larger than the widths _C1 and _H1 of the liquid flow path grooves 14a and 15a described above, and is preferably 2000 μm or less, and may be 1500 μm or less, or may be 1000 μm or less. On the other hand, the width M is preferably 100 μm or more, and may be 200 μm or more, or may be 400 μm or more. The range of the width M may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. Furthermore, the range of the width M may be determined by combining any two of the plurality of upper limit candidate values, or by combining any two of the plurality of lower limit candidate values.
The pitch of the steam flow channel grooves 16 is usually determined by the pitch of the inner liquid flow channel portions 15 .

On the other hand, the depth of the vapor flow path groove 16, indicated by N in FIG. 5, is formed to be at least greater than the depths D and J of the liquid flow path grooves 14a and 15a described above, and is preferably 300 μm or less, and may be 200 μm or less, or may be 100 μm or less. On the other hand, this depth N is preferably 10 μm or more, and may be 25 μm or more, or may be 50 μm or more. The range of the depth N may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. Furthermore, the range of the depth N may be determined by combining any two of the plurality of upper limit candidate values or any two of the plurality of lower limit candidate values.
In this way, by making the flow passage cross-sectional area of the steam flow passage groove larger than that of the liquid flow passage groove, it is possible to smoothly return the steam, which has a larger volume than the condensed liquid due to the nature of the working fluid.

In this embodiment, the cross-sectional shape of the steam flow channel groove 16 is semi-elliptical, but it is not limited to this and may be rectangular, square, trapezoidal or other quadrilateral, triangular, semicircular, with a semicircular bottom, with a semi-elliptical bottom, or a combination of any two or more of these shapes. By reducing the flow resistance of the steam, the steam channel can allow for smooth circulation of the working fluid, so the shape of the channel cross section can also be determined from this perspective.

In this embodiment, an example has been described in which one steam flow path groove 16 is formed between adjacent inner liquid flow path sections 15, but this is not limited to this, and a configuration in which two or more steam flow path grooves are arranged side by side between adjacent inner liquid flow path sections is also possible.
Furthermore, as long as the steam flow path grooves are formed in the second sheet 20, the first sheet 10 may not be formed in part or in its entirety.

The steam flow path communication grooves 17 are grooves that connect multiple steam flow path grooves 16. This allows the steam in the multiple steam flow path grooves 16 to be equalized, the steam to be transported over a wider area, and many condensate flow paths 3 to be used efficiently, making it possible to more smoothly return the working fluid.

3 and 4, the steam flow path communication groove 17 in this embodiment is formed between both end portions in the direction in which the inner liquid flow path section 15 and the steam flow path groove 16 extend, and the outer circumferential liquid flow path section 14. In addition, Fig. 7 shows a cross section taken along the line IVb-IVb in Fig. 4, which is perpendicular to the communication direction of the steam flow path communication groove 17.
2 to 4, for ease of understanding, a dotted line is added to the portion that should be the boundary between the steam flow path groove 16 and the steam flow path communication groove 17. However, this line is not necessarily a line that appears in the shape, but is a virtual line added for ease of understanding.

The steam flow path communication groove 17 may be formed so as to communicate with the adjacent steam flow path grooves 16, and its shape is not particularly limited. For example, the following configuration may be provided.
The width of the steam flow path communication groove 17 (the size in the direction perpendicular to the communication direction, the width at the opening surface of the groove), indicated by P in FIGS. 4 and 7 , is preferably 1000 μm or less, and may be 750 μm or less, or 500 μm or less. On the other hand, the width P is preferably 100 μm or more, and may be 150 μm or more, or may be 200 μm or more. The range of the width P may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. Furthermore, the range of the width P may be determined by combining any two of the plurality of upper limit candidate values, or by combining any two of the plurality of lower limit candidate values.
The depth of the steam flow path communication groove 17, indicated by Q in FIG. 7, is preferably 300 μm or less, and may be 225 μm or less, or 150 μm or less. On the other hand, the depth Q is preferably 10 μm or more, and may be 25 μm or more, or 50 μm or more. The range of the depth Q may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. The range of the depth Q may also be determined by combining any two of the plurality of upper limit candidate values, or by combining any two of the plurality of lower limit candidate values.

In this embodiment, the cross-sectional shape of the steam flow path communication groove 17 is semi-elliptical, but is not limited to this, and may be rectangular, square, trapezoid or other quadrilateral, triangular, semicircular, with a semi-circular bottom, with a semi-elliptical bottom, or a combination of any two or more of these.
The steam flow passage communication grooves can reduce the flow resistance of the steam, thereby allowing the working fluid to return smoothly, and the shape of the flow passage cross section can also be determined from this perspective.

Next, the second sheet 20 will be described. In this embodiment, the second sheet 20 is also a sheet-like member as a whole. Fig. 19 is a perspective view of the second sheet 20 as seen from the inner surface 20a side, and Fig. 20 is a plan view of the second sheet 20 as seen from the inner surface 20a side. Fig. 21 shows a cross section of the second sheet 20 when cut along XIIa-XIIa in Fig. 20. Fig. 22 shows a cross section of the second sheet 20 when cut along XIIb-XIIb in Fig. 20.
The second sheet 20 has an inner surface 20a, an outer surface 20b opposite the inner surface 20a, and a side surface 20c connecting the inner surface 20a and the outer surface 20b to form a thickness, and a pattern for returning the working fluid is formed on the inner surface 20a side. As will be described later, the inner surface 20a of this second sheet 20 and the inner surface 10a of the first sheet 10 are overlapped so as to face each other, thereby forming a hollow portion.

The second sheet 20 includes a main body 21 and an injection portion 22. The main body 21 is a sheet-like portion that forms a portion where the working fluid circulates, and in this embodiment, is a rectangle with arcs (so-called R) formed at the corners in a plan view.
However, the main body 21 of the second sheet 20 may be rectangular as in this embodiment, or may be circular, elliptical, triangular, or other polygonal, or may have a shape with a bent portion, such as an L-shape, a T-shape, or a crank shape, etc. Also, it may have a shape that combines at least two of these shapes.

Injection portion 22 is a portion where the working fluid is injected into the hollow portion formed by first sheet 10 and second sheet 20 to form sealed space 2 (see FIG. 23 ), and in this embodiment is a sheet-like shape that is square in plan view and protrudes from one side of main body 21 that is rectangular in plan view. In this embodiment, injection portion 22 of second sheet 20 has injection groove 22a formed on inner surface 20a, and side surface 20c of second sheet 20 communicates with the inside of main body 21 (the portion that will become sealed space 2).
The thickness and material of the second sheet 20 can be considered to be similar to those of the first sheet 10. However, the first sheet 10 and the second sheet 20 do not necessarily have to be the same thickness and material.

A structure for circulating the working fluid is formed on the inner surface 20a of the main body 21. Specifically, the inner surface 20a of the main body 21 is provided with an outer periphery joint 23, an outer periphery liquid flow path section 24, an inner liquid flow path section 25, a steam flow path groove 26, and a steam flow path connecting groove 27.

The outer peripheral bonding portion 23 is a surface formed on the inner surface 20a side of the main body 21 along the outer periphery of the main body 21. This outer peripheral bonding portion 23 overlaps and is diffusion bonded to the outer peripheral bonding portion 13 of the first sheet 10, thereby forming a hollow space between the first sheet 10 and the second sheet 20, and a working fluid is sealed in this hollow space to form the sealed space 2.
20 to 22 (the size in the direction perpendicular to the direction in which the peripheral bonding portion 23 extends, that is, the width at the bonding surface with the first sheet 10) of the peripheral bonding portion 23 is not particularly limited, but is preferably the same as the above-described size A of the width of the peripheral bonding portion 13 of the main body 11. However, it does not necessarily have to be the same, and it may be larger or smaller.

In addition, holes 23a that penetrate in the thickness direction (z direction) are provided at the four corners of the outer peripheral joint 23 of the main body 21. These holes 23a function as positioning means when overlapping with the first sheet 10.

The peripheral liquid flow path section 24 is a liquid flow path section and constitutes part of the condensed liquid flow path 3, which is the second flow path through which the working fluid passes when it condenses and becomes liquefied.

The peripheral liquid flow path section 24 is formed along the inside of the peripheral joining section 23 on the inner surface 20a of the main body 21. In this embodiment, the peripheral liquid flow path section 24 of the second sheet 20 is a flat surface that is flush with the peripheral joining section 23 before being joined to the first sheet 10, as can be seen from Figures 21 and 22. This closes the openings of the multiple liquid flow path grooves 14a of the first sheet 10 described above, thereby forming the condensate flow paths 3. Detailed aspects of the combination of the first sheet 10 and the second sheet 20 will be described later.
In this way, since the outer peripheral joining portion 23 and the outer peripheral liquid flow path portion 24 are flush with each other in the second sheet 20, there is no structural boundary line that distinguishes them. However, for ease of understanding, the boundary between them is indicated by a dotted line in Figures 19 and 20.

The peripheral liquid flow path section 24 preferably has the following configuration.
The width of the peripheral liquid flow path section 24 indicated by S in FIGS. 20 to 22 (the size in the direction perpendicular to the direction in which the peripheral liquid flow path section 24 extends, and the width at the joint surface with the first sheet 10) may be the same as the width B of the peripheral liquid flow path section 14 of the first sheet 10, or may be larger or smaller.

Next, we will explain the inner liquid flow path section 25. The inner liquid flow path section 25 is also a liquid flow path section and is one part that makes up the condensate flow path 3, which is the second flow path.

19 to 22, the inner liquid flow path section 25 is formed on the inner surface 20a of the main body 21, inside the annular ring of the outer peripheral liquid flow path section 24. The inner liquid flow path section 25 in this embodiment is a wall that is rectangular in plan view of the main body 21 and extends in a direction parallel to the long side (x direction), and multiple (three in this embodiment) inner liquid flow path sections 25 are arranged at predetermined intervals in a direction parallel to the short side (y direction).
In this embodiment, the surface of each inner liquid flow path portion 25 on the inner surface 20a side is formed as a flat surface before being joined to the first sheet 10. This closes the openings of the plurality of liquid flow path grooves 15a of the first sheet 10 described above, thereby forming the condensate liquid flow paths 3.

The width of the inner liquid flow path section 25 indicated by T in Figures 20 and 21 (the size in the direction in which the inner liquid flow path section 25 and the steam flow path grooves 26 are arranged, and the width at the joint surface with the first sheet 10) may be the same as the width G of the inner liquid flow path section 15 of the first sheet 10, or it may be larger or smaller. In this embodiment, they are considered to be the same.

In this embodiment, each inner liquid flow path section 25 is formed with a flat surface before bonding, but liquid flow path grooves may be formed in the same way as in the first sheet. In that case, the liquid flow path grooves may be in the same position in a plan view, or may be offset.

Next, we will explain the steam flow channel groove 26. The steam flow channel groove 26 is the portion through which vaporized steam generated when the working fluid evaporates, and constitutes part of the steam flow channel 4. Figure 20 shows the shape of the steam flow channel groove 26 in a plan view, and Figure 21 shows the cross-sectional shape of the steam flow channel groove 26.

As can be seen from these figures, the steam flow path grooves 26 are grooves formed on the inner surface 20a of the main body 21, inside the annular ring of the outer peripheral liquid flow path section 24. More specifically, the steam flow path grooves 26 in this embodiment are formed between adjacent inner liquid flow path sections 25 and between the outer peripheral liquid flow path section 24 and the inner liquid flow path section 25, and are rectangular in plan view of the main body 21, extending in a direction parallel to the long sides (x direction). A plurality of steam flow path grooves 26 (four in this embodiment) are arranged in a direction parallel to the short sides (y direction). Therefore, as can be seen from Figure 21, the second sheet 20 has a shape in the y direction in which protrusions caused by the walls of the outer peripheral liquid flow path section 24 and the inner liquid flow path section 25 and depressions caused by the steam flow path grooves 26 are repeated.
Here, since the steam flow channel groove 26 is a groove, its cross-sectional shape has a bottom portion on the outer surface 20b side and an opening on the inner surface 20a side at the opposite side facing the bottom portion.

The steam flow channel groove 26 is preferably positioned so that it overlaps with the steam flow channel groove 16 of the first sheet 10 in the thickness direction when combined with the first sheet 10. This allows the steam flow channel groove 16 and the steam flow channel groove 26 to form the steam flow channel 4.

The width of the steam flow path groove 26 indicated by U in Figures 20 and 21 (the size in the direction in which the inner liquid flow path section 25 and the steam flow path groove 26 are arranged, and the width at the opening surface of the groove) may be the same as the width M of the steam flow path groove 16 of the first sheet 10, or may be larger or smaller.
Furthermore, the depth of the vapor flow path groove 26, indicated by V in FIG. 21 , is preferably 300 μm or less, but may be 225 μm or less, or may be 150 μm or less. On the other hand, this depth V is preferably 10 μm or more, but may be 25 μm or more, or may be 50 μm or more. The range of this depth V may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. Furthermore, the range of depth V may be determined by combining any two of the plurality of upper limit candidate values, or by combining any two of the plurality of lower limit candidate values.
The depth of the steam flow channel grooves 16 of the first sheet 10 and the depth of the steam flow channel grooves 26 of the second sheet 20 may be the same, or may be greater or smaller.

In this embodiment, the cross-sectional shape of the steam flow channel groove 26 is semi-elliptical, but it may also be rectangular, square, trapezoidal or other quadrilateral, triangular, semicircular, with a semicircular bottom, with a semi-elliptical bottom, or a combination of these shapes. The steam flow channel can smoothly return the working fluid by reducing the flow resistance of the steam, so the shape of the flow channel cross section can also be determined from this perspective.

In this embodiment, an example has been described in which one steam flow path groove 26 is formed between adjacent inner liquid flow path sections 25, but this is not limited to this, and a configuration in which two or more steam flow path grooves are arranged side by side between adjacent inner liquid flow path sections is also possible.
Furthermore, as long as the first sheet 10 has steam flow path grooves, the second sheet 20 may not have steam flow path grooves in part or in its entirety.

The steam flow path communication groove 27 is a groove that connects multiple steam flow path grooves 26 and constitutes part of the steam flow path 4. This allows the steam in the multiple steam flow paths 4 to be equalized, the steam to be transported over a wider area, and many condensate flow paths 3 to be used efficiently, making it possible to more smoothly return the working fluid.

As can be seen from Figures 19, 20, and 22, the steam flow path communication groove 27 in this embodiment is formed between the end of the inner liquid flow path section 25 and the steam flow path groove 26 in the direction in which they extend, and the outer circumferential liquid flow path section 24. Also, Figure 22 shows a cross section perpendicular to the communication direction of the steam flow path communication groove 27.

The width (size in a direction perpendicular to the communication direction, width at the opening surface of the groove) of the steam flow path communication groove 27 indicated by W in FIGS. 20 and 22 may be the same as or different from the width P of the steam flow path communication groove 17 of the first sheet 10. The depth of the steam flow path communication groove 27 indicated by X in FIG. 22 is preferably 300 μm or less, and may be 225 μm or less, or 150 μm or less. Meanwhile, the depth X is preferably 10 μm or more, and may be 25 μm or more, or 50 μm or more. The range of the depth X may be determined by combining any one of the plurality of upper limit candidate values and one of the plurality of lower limit candidate values. The range of the depth X may also be determined by combining any two of the plurality of upper limit candidate values or any two of the plurality of lower limit candidate values.
Furthermore, the depth of the steam flow path communicating grooves 17 of the first sheet 10 and the depth of the steam flow path communicating grooves 27 of the second sheet 20 may be the same, or may be greater or smaller.

In this embodiment, the cross-sectional shape of the steam flow path communication groove 27 is semi-elliptical, but it is not limited to this and may be rectangular, square, trapezoidal or other quadrilateral, triangular, semicircular, with a semicircular bottom, with a semi-elliptical bottom, or a combination of these shapes. Since the steam flow path can ensure smooth circulation by reducing the flow resistance of steam, the shape of the flow path cross section can also be determined from this perspective.

Next, we will explain the structure when the first sheet 10 and the second sheet 20 are combined to form the vapor chamber 1. This explanation will help to further understand the arrangement, size, shape, etc. of each component of the first sheet 10 and the second sheet 20.
Figure 23 shows a cross section of the vapor chamber 1 cut in the thickness direction along the y direction indicated by XIII-XIII in Figure 1. This figure combines the diagram of the first sheet 10 shown in Figure 5 and the diagram of the second sheet 20 shown in Figure 21 to show the cross section of the vapor chamber 1 at this location.
Fig. 24 is an enlarged view of the portion indicated by arrow XIV in Fig. 23, and Fig. 25 shows a cross section of the vapor chamber 1 cut in the thickness direction along the x direction indicated by XV-XV in Fig. 1. This figure shows the cross section of the vapor chamber 1 at this portion by combining the view of the first sheet 10 shown in Fig. 7 and the view of the second sheet 20 shown in Fig. 22.

As can be seen from Figures 1, 2, and 23 to 25, the first sheet 10 and the second sheet 20 are stacked and diffusion bonded to form the vapor chamber 1. The inner surface 10a of the first sheet 10 and the inner surface 20a of the second sheet 20 are arranged to face each other, the main body 11 of the first sheet 10 and the main body 21 of the second sheet 20 overlap, and the injection portion 12 of the first sheet 10 and the injection portion 22 of the second sheet 20 overlap. In this embodiment, the relative positional relationship between the first sheet 10 and the second sheet 20 is configured to be appropriate by aligning the hole 13a of the first sheet 10 with the hole 23a of the second sheet 20.

The laminate of the first sheet 10 and the second sheet 20 allows the components of the main body 11 and the main body 21 to be arranged as shown in Figures 23 to 25. Specifically, they are as follows:

The outer peripheral joint portion 13 of the first sheet 10 and the outer peripheral joint portion 23 of the second sheet 20 are arranged so as to overlap, and are joined by diffusion bonding. This forms a hollow space between the first sheet 10 and the second sheet 20, and the working fluid is sealed in this space to form the sealed space 2.

The peripheral liquid flow path section 14 of the first sheet 10 and the peripheral liquid flow path section 24 of the second sheet 20 are arranged to overlap each other. As a result, the liquid flow path grooves 14a of the peripheral liquid flow path section 14 and the peripheral liquid flow path section 24 form a condensed liquid flow path 3, which is a second flow path through which condensed liquid, which is the working fluid that has been condensed and liquefied, flows.
Similarly, the inner liquid flow path section 15 of the first sheet 10 and the inner liquid flow path section 25 of the second sheet 20 are arranged to overlap each other. As a result, the liquid flow path grooves 15a of the inner liquid flow path section 15 and the inner liquid flow path section 25 form a condensate flow path 3, which is a second flow path through which the condensate flows.
In this way, the condensate flow path 3 is formed separately from the first flow path, i.e., the steam flow path 4, which allows for smooth circulation of the working fluid. In addition, by forming the condensate flow path 3 as a narrow flow path surrounded by walls on all four sides in cross section, the condensate is moved by strong capillary force, allowing for smooth circulation.

Furthermore, in this embodiment, after joining, the condensate flow path 3 and the wall portion 3a formed between adjacent condensate flow paths 3 are configured as follows: Fig. 26 shows an enlarged cross section of one condensate flow path 3. Fig. 27 shows an enlarged cross section of a wall portion 3a formed between adjacent condensate flow paths 3. This wall portion 3a is formed by the overlapping of the convex portion 15b of the inner liquid flow path portion 15 and the surface of the inner liquid flow path portion 25.
Here, the description will be given using the liquid flow path grooves 15a of the inner liquid flow path section 15, the condensate flow path 3 formed by the convex portions 15b and the inner liquid flow path section 25, and the wall portions 3a, but the same can be said for the condensate flow path 3 and wall portions 3a formed by the outer circumferential liquid flow path section 14 and the outer circumferential liquid flow path section 24. Also, the description will be given here of the wall portions 3a between adjacent condensate flow paths 3, but the same can be said for the wall portions 3a formed between the steam flow paths 4 and the condensate flow path 3.

The boundary 3b between the first sheet 10 and the second sheet 20 in the wall portion 3a, indicated by the reference symbol 3b in Fig. 27, does not coincide with the dotted line XVIb shown in Fig. 27, but is formed longer than the dotted line. Here, the dotted line XVIb represents the line at which the width of the wall portion 3a is smallest.
That is, in the wall portion 3a formed between adjacent condensate flow paths, the length in the width direction of the wall portion 3a at the boundary 3b between the first sheet 10 and the second sheet 20 in a cross-sectional view is longer than the minimum width of the wall portion 3a. Here, the "minimum width of the wall portion" means the minimum length of the wall portion 3a in the cross section of the wall portion 3a in the direction in which the condensate flow paths 3 and the steam flow paths 4 are arranged. In the cross section that is the same as this minimum width, the length of the boundary 3b is longer than the minimum width.
This increases the bonding strength between the first sheet 10 and the second sheet 20 in the wall portion 3a, and prevents the wall portion 3a from breaking even if the internal pressure of the sealed space 2 increases, or even if water is contained as the working fluid and freezes in a sub-zero environment, increasing its volume.
This also makes it possible to obtain a high bonding strength without the need for diffusion bonding, which involves growing crystal grains across the bonding interface between the first and second sheets, thereby reducing the conditions and time required for diffusion bonding and increasing productivity.

In this embodiment, as can be seen from Figure 27, the boundary 3b is curved at both ends, and the tops of the convex portions 15b forming the wall portion 3a are concave, so that the boundary 3b is longer than the minimum width of the wall portion 3a. However, the shape of the boundary 3b is not limited to this, and it is sufficient that the boundary 3b is longer than the minimum width of the wall portion. Figures 28 to 32 show other examples of the shape of the boundary 3b. All of Figures 28 to 32 correspond to Figure 27, and the dotted lines in each figure indicate the narrowest part of the wall portion 3a.
In the example of Figure 28, both ends of the boundary 3b are curved and the top of the convex portion 15b that forms the wall portion 3a is convex, so that the boundary 3b is formed longer than the minimum width of the wall portion 3a.
In the example of Figure 29, the boundary 3b is curved at both ends, the tops of the convex portions 15b forming the wall portion 3a are convex, and there is a concave shape between the convex portions, so that the boundary 3b is formed longer than the minimum width of the wall portion 3a.
In the example of FIG. 30, one end of the boundary 3b is curved convexly and the other end is curved concavely, so that the boundary 3b is formed longer than the minimum width of the wall portion 3a.
In the example of FIG. 31, the top of the convex portion 15b forming the wall portion 3a at the boundary 3b has one convex portion, and is asymmetric in the width direction so that the apex is closer to one end side.
In the example of Figure 32, the top of the convex portion 15b that forms the wall portion 3a at the boundary 3b has two convex portions, and is asymmetric in the width direction so that the apex of one convex portion is lower than the apex of the other convex portion.

The shape of the boundary as described above can be confirmed, for example, as follows.
The target vapor chamber is cut into square pieces measuring 10 mm in length and width using a wire saw, in such a way that the cross sections of the steam flow path and the condensate flow path can be easily obtained later.
The end face of the obtained square piece is cut with a microtome to expose the cross section of the flow channel, preferably in such a way that the resin can easily enter the flow channel.
The square pieces are then embedded in resin while being degassed under vacuum.
The resin-embedded square piece is trimmed with a diamond knife to obtain the required cross section, using a microtome (e.g., an ultramicrotome manufactured by Leica Microsystems) to a portion 40 μm away from the measurement target position.
The trimmed cut surface is polished to prepare a cut surface for observation. At this time, a cross-section specimen preparation device (e.g., a cross-section polisher manufactured by JOEL) is used to polish the cut surface by ion beam processing, with a protrusion width of 40 μm, a voltage of 5 kV, and a time of 6 hours.
The cut surface of the sample thus obtained is measured. At this time, a scanning electron microscope (e.g., a scanning electron microscope manufactured by Carl Zeiss) is used to observe the cut surface at a voltage of 5 kV, a working distance of 3.0 mm, and an observation magnification of 500x or 2000x. The standard observation magnification during photography is Polaroid 545.

In addition, in the condensate flow path 3 of the above-described example, from the viewpoint of exerting a stronger capillary force in the flow path, the aspect ratio (length-to-length ratio) of the flow path cross section, which is expressed by the value obtained by dividing the flow path width by the flow path height, is preferably greater than 1.0. This ratio may be 1.5 or greater, or 2.0 or greater. Alternatively, the aspect ratio may be less than 1.0. This ratio may be 0.75 or less, or 0.5 or less.
Among these, from the viewpoint of manufacturing, it is preferable that the channel width is larger than the channel height, and from this viewpoint, it is preferable that the aspect ratio is larger than 1.3.

23 to 25, the other parts will be described. As can be seen from Figures 23 and 24, the opening of the steam flow path groove 16 in the first sheet 10 and the opening of the steam flow path groove 26 in the second sheet 20 overlap so as to face each other to form a flow path, which becomes the steam flow path 4, which is the first flow path through which steam flows.
The cross-sectional area of the condensate flow path 3, which is the second flow path, is smaller than the cross-sectional area of the steam flow path 4, which is the first flow path. More specifically, when the average cross-sectional area of two adjacent steam flow paths 4 (in this embodiment, flow paths formed by one steam flow path groove 16 and one steam flow path groove 26) is _Ag and the average cross-sectional area of the plurality of condensate flow paths 3 (in this embodiment, the plurality of condensate flow paths 3 formed by one inner liquid flow path portion 15 and one inner liquid flow path groove 25) arranged between the two adjacent steam flow paths 4 is _Al , the relationship between the condensate flow paths 3 and the steam flow path 4 is such that _Al is 0.5 times or less, and preferably 0.25 times or less, of _Ag . This makes it easier for the working fluid to selectively pass through the first flow path or the second flow path depending on its phase (gas phase or liquid phase).
This relationship needs to be satisfied in at least a portion of the entire vapor chamber, and it is more preferable that this relationship be satisfied in the entire vapor chamber.

Similarly, as can be seen in Figure 25, the opening of the steam flow path communication groove 17 on the first sheet 10 and the opening of the steam flow path communication groove 27 on the second sheet 20 overlap to face each other, forming a flow path.

On the other hand, as shown in Figure 1, the inner surfaces 10a, 20a of the injection parts 12, 22 overlap so as to face each other, and the opening on the opposite side of the bottom of the injection groove 22a of the second sheet 20 is blocked by the inner surface 10a of the injection part 12 of the first sheet 10, forming an injection flow path 5 that connects the outside with the hollow part between the main bodies 11, 21.
However, after the working fluid is injected into the hollow portion from the injection flow path 5 to form the sealed space 2, the injection flow path 5 is closed, so that in the final form of the vapor chamber 1, the sealed space 2 is not connected to the outside.

In this embodiment, the injection section 12, the injection section 22, and the resulting injection flow path 5 are shown as being provided at one of a pair of longitudinal ends of the vapor chamber 1, but this is not limited to this and they may be located at any other end, or multiple injection sections may be provided. If multiple injection sections are provided, they may be located at each of a pair of longitudinal ends of the vapor chamber 1, or at one of the other pair of ends.

A working fluid is sealed in the sealed space 2 of the vapor chamber 1. There are no particular limitations on the type of working fluid, but working fluids commonly used in vapor chambers, such as pure water, ethanol, methanol, acetone, and mixtures thereof, can be used.

The vapor chamber as described above can be fabricated, for example, as follows.
Liquid flow path grooves 14a, 15a, vapor flow path grooves 16, 26, and vapor flow path connecting grooves 17, 27 are formed by half etching in metal sheets having the outer peripheral shapes of the first sheet 10 and the second sheet 20. Half etching means etching is performed partway through the thickness direction without penetrating the entire thickness.
Next, the inner surface 10a of the first sheet 10 and the inner surface 20a of the second sheet 20 are placed face to face, and are positioned using the holes 13a and 23a as positioning means, and are temporarily fastened together. The method of temporarily fastening is not particularly limited, but examples include resistance welding, ultrasonic welding, and adhesion using an adhesive.
After temporary bonding, the first sheet 10 and the second sheet 20 are then permanently bonded by diffusion bonding. This becomes the vapor chamber sheet. By adjusting the conditions during this diffusion bonding, the boundary 3b between the first sheet 10 and the second sheet 20 is deformed so that it is longer than the minimum width of the wall portion 3a, as explained above. These conditions are more relaxed than those for diffusion bonding, which grows crystal grains across the boundary, and the time required can be shortened, thereby increasing productivity.
Here, "permanently bonded" is not limited to a strict meaning, but means that the bond between the inner surface 10a of the first sheet 10 and the inner surface 20a of the second sheet 20 can be maintained to an extent that the airtightness of the sealed space 2 can be maintained when the vapor chamber 1 is in operation.

After bonding, a vacuum is drawn through the formed injection channel 5 to reduce the pressure inside the hollow portion. The working fluid is then injected into the reduced pressure hollow portion through the injection channel 5, filling the hollow portion with the working fluid. The injection channel 5 is then closed by laser melting or crimping the injection portions 12 and 22. This creates a sealed space 2, inside which the working fluid is stably held.

In this form of vapor chamber, the overlap between the internal liquid flow path section 15 and the internal liquid flow path section 25 functions as a support, preventing the sealed space from collapsing when joined or depressurized.

Next, the operation of the vapor chamber 1 will be explained. Figure 33 shows a schematic diagram of the vapor chamber 1 placed inside a portable terminal 40, which is a type of electronic device. Here, the vapor chamber 1 is represented by a dotted line because it is placed inside the housing 41 of the portable terminal 40. Such a portable terminal 40 is configured with a housing 41 that houses various electronic components and a display unit 42 that is exposed so that images can be seen outside through an opening in the housing 41. One of these electronic components is an electronic component 30 that is to be cooled by the vapor chamber 1 and is placed inside the housing 41.

The vapor chamber 1 is installed in the housing of a portable terminal or the like and is attached to an electronic component 30, such as a CPU, which is the object to be cooled. The electronic component 30 is attached directly to the outer surface 10b or outer surface 20b of the vapor chamber 1, or via another member such as a highly thermally conductive adhesive, sheet, or tape. The location of the electronic component 30 on the outer surface 10b or outer surface 20b is not particularly limited and is appropriately determined depending on the relationship with the arrangement of other components in the portable terminal or the like. In this embodiment, as shown by the dotted line in Figure 1 , the electronic component 30, which is the heat source to be cooled, is positioned on the outer surface 10b of the first sheet 10, at the center of the main body 11 in the x- and y-directions. Therefore, the electronic component 30 is shown by the dotted line in Figure 1 because it is in a blind spot and cannot be seen.
34 is a diagram illustrating the flow of the working fluid. For ease of explanation, the second sheet 20 is omitted from this diagram, and the inner surface 10a of the first sheet 10 is shown.

When the electronic component 30 generates heat, the heat is transferred by thermal conduction within the first sheet 10, and the condensate present in the sealed space 2 near the electronic component 30 absorbs the heat and evaporates. This cools the electronic component 30.

The evaporated working fluid becomes vapor and flows through the vapor flow path 4 as shown by the solid arrows in Fig. 23. This flow occurs in a direction away from the electronic component 30, so the vapor moves in a direction away from the electronic component 30.
The vapor in the vapor flow path 4 moves away from the electronic component 30, which is the heat source, and moves to the outer periphery of the vapor chamber 1, which is at a relatively low temperature, and as it moves, it is cooled as heat is absorbed by the first sheet 10 and the second sheet 20. The first sheet 10 and the second sheet 20 absorb the heat from the vapor and transfer the heat to the housing of the portable terminal device or the like that is in contact with their outer surfaces 10b and 20b, and the heat is finally released into the outside air.

The working fluid that has absorbed heat while moving through the steam flow path 4 condenses and becomes a liquid. This condensate adheres to the wall surface of the steam flow path 4. Meanwhile, because steam flows continuously through the steam flow path 4, the condensate moves to the condensate flow path 3 as if being pushed by the steam, as shown by arrow Z in Figures 24 and 25. The condensate flow path 3 of this embodiment is provided with communication openings 14c and 15c as shown in Figures 8 and 18, and therefore the condensate is distributed to the multiple condensate flow paths 3 through these communication openings 14c and 15c.
In this embodiment, the condensate flow path 3 and the steam flow path 4 are configured separately, so that the working fluid flows back smoothly.

The condensate that has entered the condensate flow path 3 moves toward the electronic component 30, which is the heat source, as indicated by the dotted straight arrow in Figure 34, due to capillary action through the condensate flow path and pressure from the steam.
At this time, the openings of the liquid flow channel grooves 14a and 15a of the condensate flow channel 3 are blocked by the second sheet 20, so that the four sides of the cross section become walls, enhancing the capillary force, thereby enabling smooth movement of the condensate.
Then, the heat from the electronic component 30, which is the heat source, causes the vaporization again, and the above process is repeated.

As described above, the vapor chamber 1 allows for good condensate circulation in the condensate flow path due to strong capillary force, thereby increasing the amount of heat transport.

In the above embodiment, an example was shown in which the liquid flow path grooves 14a and 15a were provided only in the first sheet 10, but as shown in Figure 35, liquid flow path grooves 24a and 25a may also be provided in the second sheet 20. In this case, they can be considered to be the same as the liquid flow path grooves 14a and 15a of the first sheet 10 described above.
35 , liquid flow path groove 14a and liquid flow path groove 24a, and liquid flow path groove 15a and liquid flow path groove 25a overlap to form a condensate liquid flow path 3, which is a second flow path. Furthermore, convex portions 14b between adjacent liquid flow path grooves 14a and convex portions 24b between adjacent liquid flow path grooves 24a are joined to have the above-mentioned interface 3b (joint interface), and convex portions 15b between adjacent liquid flow path grooves 15a and convex portions 25b between adjacent liquid flow path grooves 25a are joined to have the above-mentioned interface 3b (joint interface).

This example can also be considered a vapor chamber according to the present disclosure.

So far, we have described an example of a vapor chamber 1 consisting of two sheets, a first sheet 10 and a second sheet 20. However, this is not limited to this, and a vapor chamber consisting of three sheets may also be used, as shown in Figure 36.

The vapor chamber shown in FIG. 36 is a laminate of a first sheet 10, a second sheet 20, and an intermediate sheet 50 (third sheet).
The intermediate sheet 50 is disposed so as to be sandwiched between the first sheet 10 and the second sheet 20, and they are joined together.

In this example, both the inner surface 10a and the outer surface 10b of the first sheet 10 are flat. Similarly, both the inner surface 20a and the outer surface 20b of the second sheet 20 are flat.
In this case, the thickness of the first sheet 10 and the second sheet 20 is preferably 1.0 mm or less, and may be 0.5 mm or less, or 0.1 mm or less. On the other hand, the thickness is preferably 0.005 mm or more, and may be 0.015 mm or more, or may be 0.030 mm or more. This thickness range may be determined by combining any one of the multiple upper limit candidate values and one of the multiple lower limit candidate values. Furthermore, this thickness range may be determined by combining any two of the multiple upper limit candidate values, or any two of the multiple lower limit candidate values.

The intermediate sheet 50 is provided with steam flow channel grooves 51, walls 52, liquid flow channel grooves 53, and protrusions 54.
The steam flow path groove 51 is a groove that penetrates the intermediate sheet 50 in the thickness direction, and is a groove similar to the steam flow path groove 16 and the steam flow path groove 26 that are overlapped to form the steam flow path 4, which is the first flow path, and is arranged in a form corresponding to this.
The wall 52 is a wall provided between adjacent steam flow path grooves 51, and is arranged in a form corresponding to the wall formed by overlapping the outer peripheral liquid flow path section 14 and the outer peripheral liquid flow path section 24, and the inner liquid flow path section 15 and the inner liquid flow path section 25.
The liquid flow path groove 53 is a groove that is arranged on the surface of the wall 52 that faces the first sheet 10, and is arranged in a form that corresponds to the liquid flow path grooves 14 a and 15 a described above. The liquid flow path groove 53 forms a condensate flow path 3 that is a second flow path.
The convex portions 54 are convex portions that are arranged between adjacent liquid flow path grooves 53, and are arranged in a form that corresponds to the convex portions 14b and 15b described above.

When the first sheet 10, second sheet 20, and intermediate sheet 50 are joined together, the convex portion 54 is joined to the inner surface 10a of the first sheet 10, providing an interface 3b (joining interface) such as that shown in Figures 27 to 32.

The above examples of the embodiments of the present disclosure are not limited to the above, and the components can be modified and embodied without departing from the spirit of the disclosure. Furthermore, various embodiments can be created by appropriately combining the multiple components disclosed in the above embodiments. Some components may be omitted from all the components shown in each embodiment.

1 Vapor chamber 2 Sealed space 3 Condensate flow path 3a Wall 3b Boundary (bonding interface)
4 Steam flow path 10 First sheet 10a Inner surface 10b Outer surface 10c Side surface 11 Main body 12 Injection portion 13 Outer peripheral joining portion 14 Outer peripheral liquid flow path portion 14a Liquid flow path groove 14b Convex portion 14c Communication opening 15 Inner liquid flow path portion 15a Liquid flow path groove 15b Convex portion 15c Communication opening 16 Steam flow path groove 17 Steam flow path communication groove 20 Second sheet 20a Inner surface 20b Outer surface 20c Side surface 21 Main body 22 Injection portion 23 Outer peripheral joining portion 24 Outer peripheral liquid flow path portion 25 Inner liquid flow path portion 26 Steam flow path groove 27 Steam flow path communication groove

Claims (6)

A vapor chamber is a laminate of a plurality of sheets and has an enclosed space in which a working fluid is sealed,
a capillary structure in the sealed space through which the working fluid in a liquid state flows;
a vapor flow path through which the working fluid in a gaseous state flows;
In a cross-sectional view, a length of a bonding interface of the sheet at a wall portion disposed between the capillary structure and the vapor flow path is longer than a minimum width of the wall portion;
The minimum width of the wall portion is 10 μm or more and 400 μm or less.
Vapor chamber. A vapor chamber is a laminate of a plurality of sheets and has an enclosed space in which a working fluid is sealed,
The sealed space has a first flow path through which the working fluid in a gaseous state flows;
a second flow path through which the working fluid in a liquid state flows;
In a cross-sectional view, a length of a bonding interface of the sheet at a wall portion disposed between the first flow path and the second flow path is longer than a minimum width of the wall portion,
The minimum width of the wall portion is 10 μm or more and 400 μm or less.
Vapor chamber. A vapor chamber is a laminate of a plurality of sheets and has an enclosed space in which a working fluid is sealed,
The sealed space includes a plurality of first flow paths;
a second flow path provided between adjacent first flow paths,
When an average flow path cross-sectional area of two adjacent first flow paths is A _g and an average flow path cross-sectional area of a plurality of second flow paths disposed between the adjacent first flow paths is A _l , A _l is 0.5 times or less of A _g in at least a part of the flow paths,
In a cross-sectional view, a length of a bonding interface of the sheet at a wall portion disposed between the first flow path and the second flow path is longer than a minimum width of the wall portion,
The minimum width of the wall portion is 10 μm or more and 400 μm or less.
Vapor chamber. A vapor chamber according to any one of claims 1 to 3, wherein the bonding interface is curved. A vapor chamber as described in any one of claims 1 to 4, wherein the bonding interface is asymmetric in the width direction of the wall portion. The housing and
an electronic component disposed inside the housing;
and a vapor chamber according to any one of claims 1 to 5, which is disposed on the electronic component.
electronic equipment.