JP7780721B2 - Wick sheet for vapor chamber, vapor chamber and electronic device - Google Patents

Description

The present invention relates to a wick sheet for a vapor chamber, a vapor chamber, and an electronic device.

Heat-generating devices such as central processing units (CPUs), light-emitting diodes (LEDs), and power semiconductors used in mobile devices such as handheld devices and tablet computers are cooled by heat dissipation components such as heat pipes (see, for example, Patent Document 1). In recent years, thinner heat dissipation components have been required to make mobile devices thinner, and vapor chambers, which can be made thinner than heat pipes, have been developed. A working fluid is sealed inside the vapor chamber, and this working fluid absorbs and dissipates the heat from the device, thereby cooling it.

More specifically, the working fluid in the vapor chamber absorbs heat from the device in the portion closest to the device (evaporator) and evaporates into vapor (working vapor). The working vapor then diffuses away from the evaporator within the vapor flow path, where it cools and condenses into liquid. A liquid flow path with a capillary structure (wick) is provided within the vapor chamber, and the condensed working fluid (working liquid) enters the liquid flow path from the vapor flow path and flows through the liquid flow path toward the evaporator. The working liquid then absorbs heat again in the evaporator and evaporates. In this way, the working fluid circulates within the vapor chamber while repeatedly changing phases, i.e., evaporating and condensing, thereby transferring heat from the device and increasing heat dissipation efficiency.

JP 2008-82698 A

However, in a temperature environment lower than the freezing point of the working fluid sealed in the vapor chamber, the working fluid may freeze. In this case, the frozen working fluid may block part of the vapor flow path inside the vapor chamber, potentially reducing the performance of the vapor chamber.

The present invention was made in consideration of these points, and aims to provide a wick sheet for a vapor chamber, a vapor chamber, and an electronic device that can suppress deterioration in the vapor chamber's performance.

The present invention provides
A wick sheet for a vapor chamber interposed between a first sheet and a second sheet of the vapor chamber in which a working fluid is sealed,
A frame body portion;
a land portion provided within the frame portion;
a vapor flow path portion provided between the frame portion and the land portion, through which vapor of the working fluid passes;
a liquid flow path portion provided in the land portion, communicating with the vapor flow path portion, through which the liquid working fluid passes,
a wick sheet for a vapor chamber, wherein the frame portion has a plurality of frame protrusions formed in a convex shape toward the inside of the vapor flow path portion in a plan view;
to provide.

In the wick sheet for the vapor chamber described above,
The plurality of frame protrusions include a first protrusion provided on at least one of a pair of inner end portions of the frame extending in a first direction.
This may be done.

In the wick sheet for the vapor chamber described above,
The land portion has a longitudinal direction that is aligned with the first direction.
This may be done.

In addition, in the wick sheet for the vapor chamber described above,
the plurality of frame body protrusions include a second protrusion provided on at least one of a pair of inner end portions of the frame body portion extending in a second direction perpendicular to the first direction,
This may be done.

In addition, in the wick sheet for the vapor chamber described above,
The frame protrusion may have a rectangular, triangular or curved shape in a plan view.

In addition, in the wick sheet for the vapor chamber described above,
When viewed in a cross section along the thickness direction of the wick sheet, the frame convex portion has a first curved surface provided on one side in the thickness direction, a second curved surface provided on the other side in the thickness direction, and a protrusion portion where the first curved surface and the second curved surface join together and protrude into the steam flow path portion.
This may be done.

In addition, in the wick sheet for the vapor chamber described above,
When viewed in a cross section along the thickness direction, the protrusion is positioned more inward of the steam flow path than a first end of the first curved surface provided on the opposite side to the protrusion, and is positioned more inward of the steam flow path than a second end of the second curved surface provided on the opposite side to the protrusion.
This may be done.

In addition, in the wick sheet for the vapor chamber described above,
When viewed in a cross section along the thickness direction, the protrusion is positioned more inward of the steam flow path portion than a first end of the first curved surface provided on the opposite side to the protrusion, and a second end of the second curved surface provided on the opposite side to the protrusion is positioned more inward of the steam flow path portion than the protrusion.
This may be done.

In addition, in the wick sheet for the vapor chamber described above,
the plurality of frame body protrusions include first end side protrusions and second end side protrusions that are arranged alternately in a plan view,
In the first end side convex portion, when viewed in a cross section along the thickness direction, the protrusion is positioned more inward of the steam flow path portion than a second end of the second curved surface provided on the opposite side to the protrusion, and a first end of the first curved surface provided on the opposite side to the protrusion is positioned more inward of the steam flow path portion than the protrusion,
In the second end side convex portion, when viewed in a cross section along the thickness direction, the protrusion is positioned more inward of the steam flow path portion than the first end, and the second end is positioned more inward of the steam flow path portion than the protrusion.
This may be done.

The present invention also provides
A wick sheet for a vapor chamber interposed between a first sheet and a second sheet of the vapor chamber in which a working fluid is sealed,
A frame body portion;
a land portion provided within the frame portion;
a seat space provided between the frame portion and the land portion;
a groove portion provided in the land portion and communicating with the seat space,
a wick sheet for a vapor chamber, wherein the frame portion has a plurality of frame protrusions formed in a convex shape toward the inside of the sheet space in a plan view;
to provide.

The present invention also provides
The first sheet,
A second seat;
a vapor chamber including the above-mentioned wick sheet for the vapor chamber interposed between the first sheet and the second sheet;
to provide.

In the vapor chamber described above,
a condensation region in which the working fluid condenses;
an evaporation region in which the working fluid evaporates;
The frame protrusion is provided in the condensation region.
This may be done.

In addition, in the vapor chamber described above,
The working fluid having freeze expansion properties is sealed in.
This may be done.

The present invention also provides
Housing and
a device contained within the housing; and
and a vapor chamber as described above in thermal contact with the device.

This invention makes it possible to suppress deterioration in vapor chamber performance.

FIG. 1 is a schematic perspective view illustrating an electronic device according to an embodiment. FIG. 2 is a top view showing a vapor chamber according to an embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a top view of the lower sheet of FIG. FIG. 5 is a bottom view of the upper sheet of FIG. FIG. 6 is a top view of the wick sheet of FIG. FIG. 7 is an enlarged cross-sectional view of a portion of FIG. FIG. 8 is a partially enlarged top view of the liquid flow path portion shown in FIG. 9 is a partially enlarged top view showing a first protrusion provided on the frame shown in FIG. 6. FIG. 10 is a partially enlarged top view showing a second protrusion provided on the frame shown in FIG. 6. FIG. FIG. 11 is a cross-sectional view taken along line BB in FIG. FIG. 12 is a diagram illustrating a wick sheet preparation step in the vapor chamber manufacturing method according to the embodiment. FIG. 13 is a diagram for explaining an etching step in the method for manufacturing a vapor chamber according to the embodiment. FIG. 14 is a diagram for explaining a bonding step in the manufacturing method of the vapor chamber according to the embodiment. FIG. 15 is a partially enlarged top view showing a modification of FIG. FIG. 16 is a partially enlarged top view showing a modification of FIG. FIG. 17 is a cross-sectional view showing a modification of FIG. FIG. 18 is a cross-sectional view showing a modification of FIG. FIG. 19 is a top view showing a modification of FIG.

Embodiments of the present invention will now be described with reference to the drawings. Note that in the drawings accompanying this specification, the scale and aspect ratios have been appropriately altered and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

In addition, terms used in this specification that specify shapes, geometric conditions, physical characteristics, and their degrees, such as "parallel," "orthogonal," and "identical," as well as lengths, angles, and physical characteristic values, are to be interpreted without being bound by strict meaning, but also to include the range within which similar functionality can be expected. Furthermore, in the drawings, for clarity, the shapes of multiple parts that can be expected to have similar functionality are depicted in a regular pattern, but the shapes of these parts may differ from one another as long as the functionality can be expected without being bound by strict meaning. In the drawings, boundary lines indicating the joining surfaces between components are shown as simple straight lines for convenience, but they are not required to be strict straight lines, and the shape of these boundary lines is arbitrary as long as the desired joining performance can be expected.

A wick sheet for a vapor chamber, a vapor chamber, and an electronic device according to an embodiment of the present invention will be described using Figures 1 to 14. The vapor chamber 1 according to this embodiment is a device mounted on an electronic device E to cool a device D, which serves as a heat-generating body housed in the electronic device E. Examples of device D include heat-generating electronic devices (cooled devices), such as central processing units (CPUs), light-emitting diodes (LEDs), and power semiconductors used in mobile devices such as handheld devices and tablet devices.

First, we will explain electronic device E equipped with vapor chamber 1 according to this embodiment, using a tablet terminal as an example. As shown in FIG. 1, electronic device E (tablet terminal) includes housing H, device D housed within housing H, and vapor chamber 1. In electronic device E shown in FIG. 1, a touch panel display TD is provided on the front surface of housing H. Vapor chamber 1 is housed within housing H and positioned so as to be in thermal contact with device D. This allows vapor chamber 1 to receive heat generated by device D when electronic device E is in use. The heat received by vapor chamber 1 is released to the outside of vapor chamber 1 via working fluids 2a and 2b, described below. In this way, device D is effectively cooled. When electronic device E is a tablet terminal, device D corresponds to a central processing unit or the like.

Next, the vapor chamber 1 according to this embodiment will be described. As shown in FIGS. 2 and 3, the vapor chamber 1 has a sealed space 3 filled with working fluids 2a and 2b. The working fluids 2a and 2b in the sealed space 3 undergo repeated phase changes, effectively cooling the device D of the electronic device E described above. Examples of working fluids 2a and 2b include pure water, ethanol, methanol, acetone, etc., and mixtures thereof. The working fluids 2a and 2b may also have freeze-expansion properties. In other words, the working fluids 2a and 2b may be fluids that expand when frozen. Examples of working fluids 2a and 2b that have freeze-expansion properties include pure water, or aqueous solutions of pure water to which an additive such as alcohol has been added.

As shown in Figures 2 and 3, the vapor chamber 1 comprises a lower sheet 10 (first sheet), an upper sheet 20 (second sheet), and a wick sheet for the vapor chamber (hereinafter simply referred to as wick sheet 30) interposed between the lower sheet 10 and the upper sheet 20. The vapor chamber 1 according to this embodiment has the lower sheet 10, wick sheet 30, and upper sheet 20 stacked in this order.

The vapor chamber 1 is generally formed in the shape of a thin, flat plate. The planar shape of the vapor chamber 1 is arbitrary, but may be rectangular as shown in Figure 2. The planar shape of the vapor chamber 1 may be, for example, a rectangle with one side measuring 1 cm and the other 3 cm, or a square with one side measuring 15 cm. The planar dimensions of the vapor chamber 1 are arbitrary. In this embodiment, as an example, an example will be described in which the planar shape of the vapor chamber 1 is a rectangle with the X direction as the longitudinal direction. In this case, as shown in Figures 4 to 6, the lower sheet 10, upper sheet 20, and wick sheet 30 may have the same planar shape as the vapor chamber 1. Furthermore, the planar shape of the vapor chamber 1 is not limited to a rectangle, and may be any shape, such as a circle, an ellipse, an L-shape, or a T-shape.

As shown in Figure 2, the vapor chamber 1 has an evaporation region SR where the working fluids 2a and 2b evaporate, and a condensation region CR where the working fluids 2a and 2b condense.

The evaporation region SR is the region that overlaps with the device D in a planar view and is the region where the device D is attached. The evaporation region SR can be located anywhere in the vapor chamber 1. In this embodiment, the evaporation region SR is formed on one side of the vapor chamber 1 in the X direction (the left side in Figure 2). Heat from the device D is transferred to the evaporation region SR, and this heat causes the liquid working fluid (referred to as working fluid 2b as appropriate) to evaporate in the evaporation region SR. The heat from the device D can be transferred not only to the region that overlaps with the device D in a planar view, but also to the surrounding area of that region. Therefore, the evaporation region SR includes the region that overlaps with the device D in a planar view and the surrounding area. Here, a plan view refers to a view of the vapor chamber 1 as seen from a direction perpendicular to the surface that receives heat from the device D (the second upper sheet surface 20b of the upper sheet 20, described below) and the surface that releases the received heat (the first lower sheet surface 10a of the lower sheet 10, described below). For example, as shown in Figure 2, this corresponds to a view of the vapor chamber 1 as seen from above or below.

The condensation region CR is a region that does not overlap with the device D in a plan view, and is primarily a region where the vapor of the working fluid (referred to as working vapor 2a as appropriate) releases heat and condenses. The condensation region CR can also be described as the region surrounding the evaporation region SR. In this embodiment, the condensation region CR is formed on the other side of the vapor chamber 1 in the X direction (the right side in Figure 2). In the condensation region CR, heat from the working vapor 2a is released to the lower sheet 10, and the working vapor 2a is cooled and condensed in the condensation region CR.

When the vapor chamber 1 is installed inside a mobile terminal, the up-down relationship may be lost depending on the position of the mobile terminal. However, in this embodiment, for convenience, the sheet that receives heat from the device D will be referred to as the upper sheet 20, and the sheet that releases the received heat will be referred to as the lower sheet 10. For this reason, the following description will be given assuming that the lower sheet 10 is positioned on the bottom and the upper sheet 20 is positioned on the top.

As shown in FIG. 3, the lower sheet 10 has a first lower sheet surface 10a provided on the side opposite the wick sheet 30, and a second lower sheet surface 10b provided on the side opposite the first lower sheet surface 10a (i.e., the wick sheet 30 side). The lower sheet 10 may be formed flat overall, or may have a constant thickness overall. A housing member Ha that forms part of a housing H of a mobile terminal or the like is attached to this first lower sheet surface 10a. The first lower sheet surface 10a may be entirely covered by the housing member Ha. As shown in FIG. 4, alignment holes 12 may be provided at the four corners of the lower sheet 10.

As shown in FIG. 3, the upper sheet 20 has a first upper sheet surface 20a provided on the wick sheet 30 side and a second upper sheet surface 20b provided on the opposite side to the first upper sheet surface 20a. The upper sheet 20 may be formed flat overall, or may have a constant thickness overall. The above-mentioned device D is attached to this second upper sheet surface 20b. As shown in FIG. 5, alignment holes 22 may be provided at the four corners of the upper sheet 20.

As shown in FIG. 3, the wick sheet 30 comprises a sheet body 31 and a steam flow path portion 50 (sheet space) provided in the sheet body 31. The sheet body 31 has a first body surface 31a and a second body surface 31b provided on the opposite side of the first body surface 31a. The first body surface 31a is disposed on the side of the lower sheet 10, and the second body surface 31b is disposed on the side of the upper sheet 20.

The second lower sheet surface 10b of the lower sheet 10 and the first main body surface 31a of the sheet main body 31 may be permanently bonded to each other by diffusion bonding. Similarly, the first upper sheet surface 20a of the upper sheet 20 and the second main body surface 31b of the sheet main body 31 may be permanently bonded to each other by diffusion bonding. The lower sheet 10, upper sheet 20, and wick sheet 30 may be bonded by other methods, such as brazing, as long as they are permanently bonded, rather than by diffusion bonding. The term "permanently bonded" is not limited to a strict meaning and is used to mean that the lower sheet 10 and wick sheet 30 are bonded to a degree that allows the sealing of the sealed space 3 to be maintained, and that the upper sheet 20 and wick sheet 30 are bonded to a degree that allows the sealing of the sealed space 3 to be maintained when the vapor chamber 1 is in operation.

As shown in Figures 3 and 6, the sheet body 31 of the wick sheet 30 according to this embodiment has a frame portion 32 formed in the shape of a rectangular frame in plan view, and a land portion 33 provided within the frame portion 32. The frame portion 32 and the land portion 33 are not etched in the etching process described below, and the material of the wick sheet 30 remains.

In this embodiment, the frame portion 32 is formed into a rectangular frame shape in a plan view. A steam flow path portion 50 is defined inside the frame portion 32. That is, working steam 2a flows around the land portion 33 inside the frame portion 32. The frame portion 32 also has a pair of inner end portions 32a extending in the X direction and a pair of inner end portions 32b extending in the Y direction perpendicular to the X direction. A plurality of frame protrusions 70, described below, are provided on the inner end portions 32a, 32b of the frame portion 32.

In this embodiment, the land portions 33 may extend in an elongated shape with the X direction (first direction, left-right direction in FIG. 6) as the longitudinal direction in a plan view, and the planar shape of the land portions 33 may be an elongated rectangle. Furthermore, the land portions 33 may be arranged parallel to one another and spaced at equal intervals in the Y direction (second direction, up-down direction in FIG. 6). The working steam 2a is configured to flow around each land portion 33 and be transported toward the condensation region CR. This prevents the flow of the working steam 2a from being obstructed. The width w1 (see FIG. 7) of the land portion 33 may be, for example, 100 μm to 1500 μm. Here, the width w1 of the land portion 33 refers to the dimension of the land portion 33 in the Y direction and the dimension at the position of the penetration portion 34, described below, in the Z direction (thickness direction of the wick sheet 30).

The frame portion 32 and each land portion 33 are diffusion bonded to the lower sheet 10 and also to the upper sheet 20. This improves the mechanical strength of the vapor chamber 1. The wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54 (described below) form the side walls of the land portion 33. The first body surface 31a and second body surface 31b of the sheet main body 31 may be formed flat across the frame portion 32 and each land portion 33.

The steam flow path 50 is primarily a flow path through which the working steam 2a passes. The steam flow path 50 extends from the first main body surface 31a to the second main body surface 31b, penetrating the sheet body 31 of the wick sheet 30.

As shown in FIG. 6 , the steam flow path section 50 in this embodiment has a first steam passage 51 and multiple second steam passages 52. The first steam passage 51 is formed between the frame body section 32 and the land section 33. This first steam passage 51 is formed inside the frame body section 32 and continuously outside the land section 33. The first steam passage 51 has a planar shape like a rectangular frame. The second steam passage 52 is formed between adjacent land sections 33. The second steam passage 52 has a planar shape like an elongated rectangle. The multiple land sections 33 partition the steam flow path section 50 into the first steam passage 51 and multiple second steam passages 52.

As shown in FIG. 3, the first steam passage 51 and the second steam passage 52 extend from the first body surface 31a to the second body surface 31b of the seat body 31. The first steam passage 51 and the second steam passage 52 are each formed by a lower steam passage recess 53 provided in the first body surface 31a and an upper steam passage recess 54 provided in the second body surface 31b. The lower steam passage recess 53 and the upper steam passage recess 54 are connected to each other, so that the first steam passage 51 and the second steam passage 52 of the steam passage section 50 extend from the first body surface 31a to the second body surface 31b.

The lower steam flow path recess 53 is formed in a concave shape on the first main body surface 31a by etching it from the first main body surface 31a of the wick sheet 30 in an etching process described below. As a result, the lower steam flow path recess 53 has a curved wall surface 53a, as shown in FIG. 7. This wall surface 53a defines the lower steam flow path recess 53 and is curved in a shape that bulges toward the second main body surface 31b. This lower steam flow path recess 53 constitutes part (the lower half) of the first steam passage 51 and part (the lower half) of the second steam passage 52.

The upper steam flow path recess 54 is formed in a concave shape on the second main body surface 31b by etching it from the second main body surface 31b of the wick sheet 30 in an etching process described below. As a result, the upper steam flow path recess 54 has a curved wall surface 54a, as shown in FIG. 7. This wall surface 54a defines the upper steam flow path recess 54 and is curved in a shape that bulges toward the first main body surface 31a. This upper steam flow path recess 54 constitutes part (upper half) of the first steam passage 51 and part (upper half) of the second steam passage 52.

As shown in FIG. 7 , the wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54 are connected to form the through-portion 34. The wall surfaces 53a and 54a are each curved toward the through-portion 34. This allows the lower steam flow path recess 53 and the upper steam flow path recess 54 to communicate with each other. In this embodiment, the planar shape of the through-portion 34 in the first steam passage 51 is a rectangular frame like the first steam passage 51, and the planar shape of the through-portion 34 in the second steam passage 52 is an elongated rectangular like the second steam passage 52. The through-portion 34 may be defined by a ridgeline formed by the confluence of the wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54, which juts out inward. The planar area of the steam flow path section 50 is minimized at this through-portion 34. The widths w2, w2' of such through-holes 34 (see FIG. 7) may be, for example, 400 μm to 1600 μm. Here, the width w2 of the through-holes 34 corresponds to the gap between adjacent land portions 33 in the Y direction. Furthermore, the width w2' of the through-holes 34 corresponds to the gap between the frame portion 32 (more specifically, the inner ends 32a, 32b of the frame portion 32 that do not have the frame protrusions 70 described below) and the land portion 33.

The position of the through-hole 34 in the Z direction (thickness direction of the wick sheet 30, vertical direction in Figure 7) may be midway between the first lower sheet surface 10a and the upper sheet surface 20b, or may be shifted downward or upward from the midway position. The position of the through-hole 34 is arbitrary as long as the lower steam flow path recess 53 and the upper steam flow path recess 54 are connected.

In addition, in this embodiment, the cross-sectional shapes of the first steam passage 51 and the second steam passage 52 are formed to include a through-hole 34 defined by a ridge line formed to protrude inward, but this is not limited to this. For example, the cross-sectional shapes of the first steam passage 51 and the second steam passage 52 may be trapezoidal, rectangular, or barrel-shaped.

The steam flow path section 50, including the first steam path 51 and second steam path 52 configured in this manner, constitutes part of the sealed space 3 described above. As shown in FIG. 3, the steam flow path section 50 in this embodiment is defined primarily by the lower sheet 10, the upper sheet 20, and the frame portion 32 and land portion 33 of the sheet main body 31 described above. Each steam path 51, 52 has a relatively large flow path cross-sectional area to allow the working steam 2a to pass through.

Here, in order to clarify the drawing, Figure 3 shows the first steam passage 51 and second steam passage 52, etc., enlarged, and the number and arrangement of these steam passages 51, 52, etc. differ from Figures 2 and 6.

Although not shown, a plurality of support portions that support the land portion 33 on the frame portion 32 may be provided within the steam flow path portion 50. Also, support portions that support adjacent land portions 33 may be provided. These support portions may be provided on both sides of the land portion 33 in the X direction, or on both sides of the land portion 33 in the Y direction.
The support portion is preferably formed so as not to impede the flow of the working steam 2a diffusing through the steam flow path portion 50. For example, the support portion may be disposed on one of the first main body surface 31a and the second main body surface 31b of the sheet body 31 of the wick sheet 30, with a space forming a steam flow path recess formed on the other side. This allows the thickness of the support portion to be thinner than the thickness of the sheet body 31, preventing the first steam path 51 and the second steam path 52 from being separated in the X direction and the Y direction.

As shown in Figure 6, alignment holes 35 may be provided at the four corners of the sheet body 31 of the wick sheet 30.

Furthermore, as shown in FIG. 2, the vapor chamber 1 may further include an injection portion 4 at one edge in the X direction, which injects the working fluid 2b into the sealed space 3. In the embodiment shown in FIG. 2, the injection portion 4 is disposed on the evaporation region SR side and protrudes outward from the edge on the evaporation region SR side.

More specifically, the injection section 4 may be configured to include a lower injection protrusion 11 (see FIG. 4) that constitutes the lower sheet 10, an upper injection protrusion 21 (see FIG. 5) that constitutes the upper sheet 20, and a wick sheet injection protrusion 36 (see FIG. 6) that constitutes the sheet body 31 of the wick sheet 30. An injection flow path 37 is formed in the wick sheet injection protrusion 36. This injection flow path 37 extends from the first body surface 31a to the second body surface 31b of the sheet body 31 and penetrates the sheet body 31 (wick sheet injection protrusion 36) in the Z direction. The injection flow path 37 is also connected to the vapor flow path section 50, and the working fluid 2b is injected into the sealed space 3 through the injection flow path 37. Depending on the arrangement of the liquid flow path section 60, the injection flow path 37 may also be connected to the liquid flow path section 60. The upper and lower surfaces of the wick sheet injection protrusion 36 are flat, and the upper surface of the lower injection protrusion 11 and the lower surface of the upper injection protrusion 21 are also flat. The planar shapes of each injection protrusion 11, 21, and 36 may be the same.

In this embodiment, the injection portion 4 is shown as being provided on one of a pair of edges in the X direction of the vapor chamber 1, but this is not limited to this and the injection portion 4 can be provided at any position. Furthermore, the injection flow path 37 provided in the wick sheet injection protrusion 36 does not need to penetrate the sheet main body 31 as long as it can inject the working fluid 2b. In this case, the injection flow path 37 communicating with the vapor flow path portion 50 can be formed by etching only one of the first main body surface 31a and the second main body surface 31b of the sheet main body 31.

As shown in Figures 3, 6, and 7, a liquid flow path portion 60 (groove portion) through which mainly the working fluid 2b passes is provided on the second main body surface 31b of the sheet main body 31 of the wick sheet 30. This liquid flow path portion 60 constitutes part of the sealed space 3 and is connected to the vapor flow path portion 50. The liquid flow path portion 60 is configured as a capillary structure (wick) for transporting the working fluid 2b to the evaporation region SR. In this embodiment, the liquid flow path portion 60 is provided on the second main body surface 31b of each land portion 33 of the wick sheet 30. The liquid flow path portion 60 may be formed over the entire second main body surface 31b of each land portion 33. The liquid flow path portion 60 does not have to be provided on the first main body surface 31a of each land portion 33.

The liquid flow path section 60 is composed of multiple grooves provided on the second main body surface 31b. In this embodiment, as shown in Figure 8, the liquid flow path section 60 has multiple liquid flow path main grooves 61 through which the hydraulic fluid 2b passes, and multiple liquid flow path communication grooves 65 that communicate with the liquid flow path main grooves 61.

As shown in FIG. 8, each liquid flow path mainstream groove 61 is formed to extend in the X direction. The liquid flow path mainstream groove 61 has a smaller flow path cross-sectional area than the first vapor passage 51 or the second vapor passage 52 of the vapor flow path section 50, so that the working fluid 2b flows mainly by capillary action. As a result, the liquid flow path mainstream groove 61 is configured to transport the working fluid 2b condensed from the working vapor 2a to the evaporation region SR. The liquid flow path mainstream grooves 61 may be arranged at equal intervals in the Y direction.

The liquid flow path mainstream grooves 61 are formed by etching from the second main body surface 31b of the sheet body 31 of the wick sheet 30 in an etching process described below. As a result, the liquid flow path mainstream grooves 61 have curved wall surfaces 62, as shown in Figure 7. These wall surfaces 62 define the liquid flow path mainstream grooves 61 and are curved in a shape that bulges toward the first main body surface 31a.

As shown in Figures 7 and 8, the width w3 (dimension in the Y direction) of the liquid flow path mainstream groove 61 may be, for example, 5 μm to 150 μm. Note that the width w3 of the liquid flow path mainstream groove 61 refers to the dimension at the second main body surface 31b. Also, as shown in Figure 7, the depth h1 (dimension in the Z direction) of the liquid flow path mainstream groove 61 may be, for example, 3 μm to 150 μm.

As shown in FIG. 8 , each liquid flow path communication groove 65 extends in a direction different from the X direction. In this embodiment, each liquid flow path communication groove 65 is formed to extend in the Y direction, perpendicular to the liquid flow path mainstream grooves 61. Some liquid flow path communication grooves 65 are arranged to connect adjacent liquid flow path mainstream grooves 61. Other liquid flow path communication grooves 65 are arranged to connect the vapor flow path section 50 (first vapor passage 51 or second vapor passage 52) to the liquid flow path mainstream groove 61. In other words, the liquid flow path communication groove 65 extends from the edge of the land portion 33 in the Y direction to the liquid flow path mainstream groove 61 adjacent to that edge. In this way, the first vapor passage 51 or second vapor passage 52 of the vapor flow path section 50 is connected to the liquid flow path mainstream groove 61.

The liquid flow path communication groove 65 has a smaller flow path cross-sectional area than the first steam passage 51 or the second steam passage 52 of the steam flow path section 50, so that the working fluid 2b flows mainly by capillary action. The liquid flow path communication grooves 65 may be arranged at equal intervals in the X direction.

Like the liquid flow path mainstream groove 61, the liquid flow path connecting groove 65 is also formed by etching, and has wall surfaces (not shown) formed in a curved shape similar to the liquid flow path mainstream groove 61. As shown in FIG. 8 , the width w4 (dimension in the X direction) of the liquid flow path connecting groove 65 may be equal to the width w3 of the liquid flow path mainstream groove 61, or may be greater or smaller than the width w3. The depth of the liquid flow path connecting groove 65 may be equal to the depth h1 of the liquid flow path mainstream groove 61, or may be greater or smaller than the depth h1.

As shown in FIG. 8 , liquid flow path convexity rows 63 are provided between adjacent liquid flow path mainstream grooves 61. Each liquid flow path convexity row 63 includes a plurality of liquid flow path convexities 64 (liquid flow path protrusions) arranged in the X direction. The liquid flow path convexities 64 are provided within the liquid flow path section 60 and protrude from the sheet main body 31 to abut against the upper sheet 20. Each liquid flow path convexity 64 is formed rectangularly in a plan view with the X direction as its longitudinal direction. A liquid flow path mainstream groove 61 is interposed between adjacent liquid flow path convexities 64 in the Y direction, and a liquid flow path communication groove 65 is interposed between adjacent liquid flow path convexities 64 in the X direction. The liquid flow path communication groove 65 is formed to extend in the Y direction and connects adjacent liquid flow path mainstream grooves 61 in the Y direction. This allows hydraulic fluid 2b to flow back and forth between these liquid flow path mainstream grooves 61.

The liquid flow path convex portion 64 is a portion that is not etched in the etching process described below, and the material of the wick sheet 30 remains. In this embodiment, as shown in Figure 8, the planar shape of the liquid flow path convex portion 64 (the shape at the position of the second main body surface 31b of the sheet main body 31 of the wick sheet 30) is rectangular.

In this embodiment, the liquid flow path protrusions 64 are arranged in a staggered pattern. More specifically, the liquid flow path protrusions 64 of liquid flow path protrusion rows 63 adjacent to each other in the Y direction are arranged with a mutual offset in the X direction. This offset may be half the arrangement pitch of the liquid flow path protrusions 64 in the X direction. The width w5 (dimension in the Y direction) of the liquid flow path protrusions 64 may be, for example, 5 μm to 500 μm. Note that the width w5 of the liquid flow path protrusions 64 refers to the dimension on the second main body surface 31b. Note that the arrangement of the liquid flow path protrusions 64 is not limited to a staggered pattern and may be arranged in parallel. In this case, the liquid flow path protrusions 64 of the liquid flow path protrusion rows 63 adjacent to each other in the Y direction are also aligned in the X direction.

The liquid flow path mainstream groove 61 includes a liquid flow path intersection 66 that communicates with the liquid flow path communication groove 65. At the liquid flow path intersection 66, the liquid flow path mainstream groove 61 and the liquid flow path communication groove 65 communicate in a T-shape. This prevents the liquid flow path communication groove 65 on the other side (e.g., the lower side in FIG. 8 ) from communicating with the liquid flow path mainstream groove 61 at the liquid flow path intersection 66, where one liquid flow path mainstream groove 61 communicates with the liquid flow path communication groove 65 on one side (e.g., the upper side in FIG. 8 ). This prevents the wall surface 62 of the liquid flow path mainstream groove 61 from being cut out on both sides (the upper and lower sides in FIG. 8 ) at the liquid flow path intersection 66, leaving one side of the wall surface 62 intact. This allows capillary action to be imparted to the working fluid in the liquid flow path mainstream groove 61 at the liquid flow path intersection 66 as well, preventing a decrease in the driving force of the working fluid 2b toward the evaporation region SR at the liquid flow path intersection 66.

Next, the frame body protrusions 70 provided on the frame body portion 32 will be described. When viewed in the Z direction (thickness direction of the wick sheet 30) (in a plan view), the frame body portion 32 has multiple frame body protrusions 70 that are formed in a convex shape toward the inside of the steam flow path portion 50. In other words, the frame body portion 32 has multiple frame body protrusions 70 that are formed in a convex shape toward the inside of the steam flow path portion 50 in a plan view, and are provided at different positions from each other in a plan view.

9 and 10 , the frame protrusion 70 is formed in a convex shape toward the first steam passage 51 of the steam flow path portion 50 in a plan view. In the present embodiment, the frame protrusion 70 has a rectangular shape in a plan view. Furthermore, the frame protrusions 70 are provided at different positions on the inner end portions 32 a, 32 b of the frame portion 32 in a plan view.
In this embodiment, the frame protrusions 70 are arranged at equal intervals around the entire periphery of the inner ends 32a and 32b of the frame portion 32 in a plan view.

The multiple frame body protrusions 70 include first protrusions 71 provided on a pair of inner end portions 32a extending in the X direction of the frame body 32, and second protrusions 72 provided on a pair of inner end portions 32b extending in the Y direction of the frame body 32.

As shown in FIG. 9, the first protrusions 71 protrude in the Y direction toward the first steam passage 51 in a plan view and are arranged side by side in the X direction. The first protrusions 71 may be arranged at equal intervals in the X direction. Also, as shown in FIG. 10, the second protrusions 72 protrude in the X direction toward the first steam passage 51 in a plan view and are arranged side by side in the Y direction. The second protrusions 72 may be arranged at equal intervals in the Y direction.

The frame protrusions 70 (first protrusions 71 and second protrusions 72) are formed by etching the first body surface 31a and the second body surface 31b of the wick sheet 30 in an etching process described below. More specifically, as shown in FIG. 11 , when viewed in a cross section along the Z direction (a cross section viewed in the X direction in FIG. 9 ), the frame protrusions 70 have a lower curved surface 70d (first curved surface) on one side in the Z direction (the lower side in FIG. 11 ) and an upper curved surface 70e (second curved surface) on the other side in the Z direction (the upper side in FIG. 11 ). The wall surface 53a of the lower steam flow path recess 53 described above includes this lower curved surface 70d, and the wall surface 54a of the upper steam flow path recess 54 described above includes this upper curved surface 70e. As shown by the dashed lines in Figure 11, the inner ends 32a, 32b of the frame 32 similarly have a lower curved surface 32d and an upper curved surface 32e. The wall surface 53a of the lower steam flow path recess 53 also includes this lower curved surface 32d, and the wall surface 54a of the upper steam flow path recess 54 also includes this upper curved surface 32e. The lower curved surface 70d of the frame protrusion 70 is formed to protrude from the lower curved surface 32d of the inner ends 32a, 32b toward the first steam path 51. The upper curved surface 70e of the frame protrusion 70 is formed to protrude from the upper curved surface 32e of the inner ends 32a, 32b toward the first steam path 51.

The lower curved surface 70d is formed in a concave shape on the first main body surface 31a by etching it from the first main body surface 31a of the wick sheet 30 in an etching process described below. As a result, the lower curved surface 70d is formed in a curved shape, as shown in FIG. 11. The lower curved surface 70d is curved in a shape that bulges toward the second main body surface 31b. This lower curved surface 70d defines a portion (the lower half) of the frame convex portion 70.

The upper curved surface 70e is formed in a concave shape on the second main body surface 31b by etching it from the second main body surface 31b of the wick sheet 30. As a result, the upper curved surface 70e is formed in a curved shape, as shown in FIG. 11. The upper curved surface 70e is curved in a shape that bulges toward the first main body surface 31a. This upper curved surface 70e defines a portion (upper half) of the frame protrusion 70.

As shown in FIG. 11 , a protrusion 70c is formed at the intersection of the lower curved surface 70d and the upper curved surface 70e. The protrusion 70c protrudes into the first steam passage 51. When viewed in a cross section along the Z direction, the frame convex portion 70 has a lower end portion 70a of the lower curved surface 70d located opposite the protrusion 70c, and an upper end portion 70b of the upper curved surface 70e located opposite the protrusion 70c. When viewed in a cross section along the Z direction, the lower end portion 70a is the intersection point between the lower curved surface 70d and the first main body surface 31a, and the upper end portion 70b is the intersection point between the upper curved surface 70e and the second main body surface 31b. In this embodiment, the protrusion 70c is positioned closer to the inside of the first steam passage 51 (to the right in FIG. 11) than the lower end 70a, and is positioned closer to the inside of the first steam passage 51 than the upper end 70b. Note that the outline of the frame protrusion 70 (first protrusion 71) depicted in FIG. 9 corresponds to the outline of the protrusion 70c in a plan view.

Although not shown, the cross section of the frame body convex portion 70 (first convex portion 71) when viewed from the Y direction in Figure 9 also has a lower curved surface, an upper curved surface, and a protrusion, similar to Figure 11. Furthermore, the cross section of the frame body convex portion 70 (second convex portion 72) in Figure 10 is also similar to Figure 11.

As shown in FIG. 9, the height h2 (dimension in the Y direction) of the first convex portion 71 may be greater than the surface roughness (arithmetic mean height Ra defined in JIS B 0601-2001) of the inner ends 32a and 32b. The arithmetic mean height Ra may be measured using a scanning white light interferometer, VertScan, manufactured by Ryoka Systems Co., Ltd. The arithmetic mean height Ra of the inner ends 32a and 32b may be, for example, 0.1 μm to 5 μm, and the height h2 of the first convex portion 71 may be, for example, 10 μm to 200 μm. Note that the height h2 of the first convex portion 71 is the dimension of the first convex portion 71 in the Y direction, as shown in FIG. 11, and refers to the dimension at the position where the through-hole 34 is located in the Z direction. Also, as shown in FIG. 9, the width w6 (dimension in the X direction) of the first convex portion 71 may be, for example, 100 μm to 1000 μm. The first protrusions 71 may have the same shape and dimensions as each other. Furthermore, as shown in FIG. 9, the distance p1 between one first protrusion 71 and the adjacent first protrusion 71 may be, for example, 100 μm to 1000 μm. In other words, the first protrusions 71 may be arranged side by side in the X direction at an arrangement pitch of distance p1.

10, the height h3 (dimension in the X direction) of the second convex portion 72 may be equal to the height h2 of the first convex portion 71. As shown in FIG. 10, the width w7 (dimension in the Y direction) of the second convex portion 72 may be equal to the width w6 of the first convex portion 71. The second convex portions 72 may have the same shape and dimensions as one another. As shown in FIG. 10, the spacing p2 between adjacent second convex portions 72 may be equal to the spacing p1 between the first convex portions 71. That is, the second convex portions 72 may be arranged side by side in the second direction Y at the same arrangement pitch as the arrangement pitch of the first convex portions 71. In this way, the first convex portions 71 and the second convex portions 72 may have the same shape and dimensions as one another and be arranged at equal intervals around the entire circumference of the inner ends 32a and 32b of the frame body portion 32 in a plan view. However, this is not limiting, and the first convex portions 71 and the second convex portions 72 may have different shapes and dimensions. Furthermore, the first convex portions 71 and the second convex portions 72 may be arranged at different intervals.

The materials constituting the lower sheet 10, upper sheet 20, and wick sheet 30 are not particularly limited as long as they have good thermal conductivity. However, the lower sheet 10, upper sheet 20, and wick sheet 30 may contain, for example, copper or a copper alloy. In this case, the thermal conductivity of each sheet 10, 20, and 30 can be increased, thereby improving the heat dissipation efficiency of the vapor chamber 1. Furthermore, when pure water is used as the working fluids 2a and 2b, corrosion can be prevented. However, other metal materials such as aluminum or titanium, or other metal alloy materials such as stainless steel can also be used for these sheets 10, 20, and 30 as long as the desired heat dissipation efficiency can be achieved and corrosion can be prevented.

Furthermore, the thickness t1 of the vapor chamber 1 shown in FIG. 3 may be, for example, 100 μm to 1000 μm. By making the thickness t1 of the vapor chamber 1 100 μm or more, the vapor flow path section 50 can be properly secured, allowing the vapor chamber 1 to function properly. On the other hand, by making the thickness t1 1000 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too large.

The thickness t2 of the lower sheet 10 may be, for example, 6 μm to 100 μm. By making the thickness t2 of the lower sheet 10 6 μm or more, the mechanical strength of the lower sheet 10 can be ensured. On the other hand, by making the thickness t2 of the lower sheet 10 100 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick. Similarly, the thickness t3 of the upper sheet 20 may be set to the same as the thickness t2 of the lower sheet 10. The thickness t3 of the upper sheet 20 and the thickness t2 of the lower sheet 10 may be different.

The thickness t4 of the wick sheet 30 may be, for example, 50 μm to 400 μm. By making the thickness t4 of the wick sheet 30 50 μm or more, the vapor flow path section 50 can be properly secured, allowing the vapor chamber 1 to function properly. On the other hand, by making it 400 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too large.

Next, a method for manufacturing the vapor chamber 1 of this embodiment configured as described above will be described using Figures 12 to 14. Note that Figures 12 to 14 show the same cross section as the cross section of Figure 3.

Here, we will first explain the process for manufacturing the wick sheet 30.

First, as shown in Figure 12, as a preparation step, a flat metal material sheet M including a first material surface Ma and a second material surface Mb is prepared.

After the preparation process, an etching process is performed in which the metal material sheet M is etched from the first material surface Ma and the second material surface Mb, as shown in Figure 13, to form the steam flow path portion 50 and the liquid flow path portion 60.

More specifically, a patterned resist film (not shown) is formed on the first material surface Ma and the second material surface Mb of the metal material sheet M by photolithography. The pattern of this resist film includes the pattern of the frame convex portion 70 described above. Next, the first material surface Ma and the second material surface Mb of the metal material sheet M are etched through the openings in the patterned resist film. As a result, the first material surface Ma and the second material surface Mb of the metal material sheet M are etched in a pattern, forming the steam flow path portion 50 and the liquid flow path portion 60 as shown in FIG. 13 . The frame convex portion 70 is also formed by this etching.
The etching solution may be, for example, an iron chloride-based etching solution such as an aqueous ferric chloride solution, or a copper chloride-based etching solution such as an aqueous copper chloride solution.

The etching may be performed simultaneously on the first material surface Ma and the second material surface Mb of the metal material sheet M. However, this is not limited to this, and the etching of the first material surface Ma and the second material surface Mb may be performed in separate processes. Furthermore, the steam flow path section 50 and the liquid flow path section 60 may be formed by etching simultaneously, or may be formed in separate processes.

In the etching step, the first material surface Ma and the second material surface Mb of the metal material sheet M are etched to obtain a predetermined outer contour shape as shown in FIG.
That is, the edge of the wick sheet 30 is formed.

In this way, the wick sheet 30 according to this embodiment is obtained.

After the wick sheet 30 manufacturing process, the lower sheet 10, upper sheet 20, and wick sheet 30 are joined together in the joining process, as shown in Figure 14. The lower sheet 10 and upper sheet 20 may be formed from rolled material having the desired thickness.

More specifically, first, the lower sheet 10, wick sheet 30, and upper sheet 20 are laminated in this order. In this case, the first main body surface 31a of the wick sheet 30 is placed on the second lower sheet surface 10b of the lower sheet 10, and the first upper sheet surface 20a of the upper sheet 20 is placed on the second main body surface 31b of the wick sheet 30. At this time, the alignment holes 12 in the lower sheet 10, the alignment holes 35 in the wick sheet 30, and the alignment holes 22 in the upper sheet 20 are used to align the sheets 10, 20, and 30.

Next, the lower sheet 10, the wick sheet 30 and the upper sheet 20 are temporarily fixed together.
For example, these sheets 10, 20, 30 may be temporarily joined by spot resistance welding, or these sheets 10, 20, 30 may be temporarily joined by laser welding.

Next, the lower sheet 10, wick sheet 30, and upper sheet 20 are permanently bonded together by diffusion bonding. Diffusion bonding involves closely bonding the lower sheet 10 and wick sheet 30, as well as the wick sheet 30 and upper sheet 20, and then applying pressure and heat in the stacking direction in a controlled atmosphere, such as a vacuum or inert gas, to bond them together by utilizing atomic diffusion that occurs at the bonding surfaces. Diffusion bonding involves heating the materials of each sheet 10, 20, and 30 to a temperature close to, but lower than, their melting points, thereby preventing the sheets 10, 20, and 30 from melting and deforming. More specifically, the frame portion 32 of the wick sheet 30 and the first main body surface 31a of each land portion 33 are diffusion bonded to the second lower sheet surface 10b of the lower sheet 10. Additionally, the frame portion 32 of the wick sheet 30 and the second main body surface 31b of each land portion 33 are diffusion bonded to the first upper sheet surface 20a of the upper sheet 20. In this manner, the sheets 10, 20, and 30 are diffusion bonded together, forming a sealed space 3 having a vapor flow path portion 50 and a liquid flow path portion 60 between the lower sheet 10 and the upper sheet 20. In the injection portion 4 described above, the lower injection protrusion 11 of the lower sheet 10 is diffusion bonded to the wick sheet injection protrusion 36 of the wick sheet 30, and the wick sheet injection protrusion 36 is diffusion bonded to the upper injection protrusion 21 of the upper sheet 20, forming a closed space for the injection flow path 37.

After the joining process, hydraulic fluid 2b is injected into the sealed space 3 from the injection section 4. At this time, the hydraulic fluid 2b may be injected in an amount greater than the total volume of the space formed by each liquid flow path main groove 61 and each liquid flow path connecting groove 65 of the liquid flow path section 60.

Then, the injection flow path 37 is sealed. For example, the injection portion 4 may be irradiated with laser light to partially melt the injection portion 4 and seal the injection flow path 37. This blocks communication between the sealed space 3 and the outside, sealing the working fluid 2b in the sealed space 3 and preventing the working fluid 2b in the sealed space 3 from leaking to the outside. Note that the injection flow path 37 can be sealed by crimping the injection portion 4 (pressing it to cause plastic deformation) or by brazing.

In this way, the vapor chamber 1 according to this embodiment is obtained.

Next, we will explain how the vapor chamber 1 operates, i.e., how the device D is cooled.

The vapor chamber 1 obtained as described above is installed in the housing H of a mobile terminal or the like, and a device D, such as a CPU, which is the device to be cooled, is attached to the second upper sheet surface 20b of the upper sheet 20 (or the vapor chamber 1 is attached to the device D). Due to its surface tension, the working fluid 2b in the sealed space 3 adheres to the wall surfaces of the sealed space 3, namely, the wall surface 53a of the lower vapor flow path recess 53, the wall surface 54a of the upper vapor flow path recess 54, the wall surface 62 of the liquid flow path main groove 61 of the liquid flow path section 60, and the wall surface of the liquid flow path connecting groove 65. The working fluid 2b can also adhere to the portion of the second lower sheet surface 10b of the lower sheet 10 exposed to the lower vapor flow path recess 53. Furthermore, the working fluid 2b can also adhere to the portion of the first upper sheet surface 20a of the upper sheet 20 exposed to the upper vapor flow path recess 54, the liquid flow path main groove 61, and the liquid flow path connecting groove 65.

When device D generates heat in this state, the working fluid 2b present in the evaporation region SR (see Figure 6) receives heat from device D. The received heat is absorbed as latent heat, causing the working fluid 2b to evaporate (vaporize), generating working vapor 2a. Much of the generated working vapor 2a diffuses within the lower steam flow path recess 53 and upper steam flow path recess 54 that form the sealed space 3 (see the solid arrows in Figure 6). The working vapor 2a in each steam flow path recess 53, 54 leaves the evaporation region SR, and much of the working vapor 2a is transported to the condensation region CR (the right-hand portion in Figure 6), which has a relatively low temperature. In the condensation region CR, the working vapor 2a is cooled by radiating heat primarily to the lower sheet 10. The heat received by the lower sheet 10 from the working vapor 2a is transferred to the outside air via the housing member Ha (see Figure 3).

In the condensation region CR, the working vapor 2a radiates heat to the lower sheet 10, losing the latent heat it absorbed and condensing in the evaporation region SR, generating working fluid 2b. The generated working fluid 2b adheres to the wall surfaces 53a, 54a of each vapor flow recess 53, 54, the second lower sheet surface 10b of the lower sheet 10, and the first upper sheet surface 20a of the upper sheet 20. Because the working fluid 2b continues to evaporate in the evaporation region SR, the working fluid 2b in the liquid flow path section 60 outside the evaporation region SR (i.e., the condensation region CR) is transported toward the evaporation region SR by capillary action in each liquid flow path mainstream groove 61 (see dashed arrows in Figure 6). As a result, the working fluid 2b adhering to the wall surfaces 53a, 54a, the second lower sheet surface 10b, and the first upper sheet surface 20a moves into the liquid flow path section 60, passes through the liquid flow path connecting groove 65, and enters the liquid flow path mainstream groove 61. In this way, the working fluid 2b is filled into each liquid flow path main groove 61 and each liquid flow path connecting groove 65. As a result, the filled working fluid 2b obtains a driving force toward the evaporation region SR due to the capillary action of each liquid flow path main groove 61, and is smoothly transported toward the evaporation region SR.

In the liquid flow path section 60, each liquid flow path mainstream groove 61 is connected to adjacent liquid flow path mainstream grooves 61 via the corresponding liquid flow path connection grooves 65. This allows working fluid 2b to flow between adjacent liquid flow path mainstream grooves 61, preventing dryout in the liquid flow path mainstream grooves 61. As a result, capillary action is imparted to the working fluid 2b in each liquid flow path mainstream groove 61, and the working fluid 2b is transported smoothly toward the evaporation region SR.

When the working fluid 2b reaches the evaporation region SR, it receives heat from the device D and evaporates again. The working vapor 2a that evaporates from the working fluid 2b passes through the liquid flow path connecting groove 65 in the evaporation region SR, moves to the lower vapor flow path recess 53 and upper vapor flow path recess 54, which have large flow path cross-sectional areas, and diffuses within each vapor flow path recess 53, 54. In this way, the working fluids 2a, 2b circulate within the sealed space 3 while repeatedly changing phases, i.e., evaporating and condensing, transporting and releasing heat from the device D. As a result, the device D is cooled.

The working fluid 2b generated by condensing the working steam 2a fills and remains in the liquid flow path main groove 61 and the liquid flow path connecting groove 65 of the liquid flow path section 60. However, in general, some of the working fluid 2b does not fill these grooves and may instead adhere to the wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54 due to surface tension. In other words, some of the working fluid 2b may adhere to the inner ends 32a, 32b of the frame section 32.

In contrast, in this embodiment, frame protrusions 70 are provided on the inner ends 32a, 32b of the frame 32. This increases the contact area between the hydraulic fluid 2b and the frame 32. This allows the hydraulic fluid 2b to wet and spread across the frame 32. As a result, the hydraulic fluid 2b can wet, spread, and disperse across the inner ends 32a, 32b of the frame 32, preventing it from remaining concentrated in specific areas.

When an electronic device E equipped with a vapor chamber 1 is placed in a temperature environment below the freezing point of the working fluids 2a and 2b, the working fluid 2b adhering to the inner ends 32a and 32b of the frame body 32 may freeze. Even in such a case, the working fluid 2b is dispersed at the inner ends 32a and 32b of the frame body 32, preventing the frozen working fluid 2b from blocking the first vapor passage 51 of the vapor flow path section 50. This prevents the flow of working vapor 2a in the first vapor passage 51 from being impeded by freezing of the working fluid 2b, thereby preventing a decrease in performance of the vapor chamber 1.

According to this embodiment, the frame 32 has multiple frame protrusions 70 formed in a convex shape toward the inside of the vapor flow path 50 in a plan view. This increases the contact area between the working fluid 2b and the frame 32, allowing the working fluid 2b to spread across the frame 32. This allows the working fluid 2b to spread and disperse at the inner ends 32a, 32b of the frame 32, preventing it from remaining concentrated in a specific area. This prevents the frozen working fluid 2b from blocking the vapor flow path 50, even if the electronic device E equipped with the vapor chamber 1 is placed in a temperature environment below the freezing point of the working fluids 2a, 2b and the working fluid 2b adhering to the inner ends 32a, 32b of the frame 32 freezes. This prevents performance degradation of the vapor chamber 1.

In addition, according to this embodiment, the multiple frame protrusions 70 include first protrusions 71 provided on a pair of inner ends 32a extending in the X direction. This allows the working fluid 2b to spread and disperse in the direction in which the land portion 33 extends, i.e., the direction in which the working vapor 2a flows. This prevents frozen working fluid 2b from blocking the vapor passage in the vapor flow path 50 that extends in the direction in which the working vapor 2a flows. In this embodiment, an evaporation region SR is provided on one side in the direction in which the land portion 33 extends, and a condensation region CR is provided on the other side. This allows the working fluid 2b adhering to the condensation region CR to spread and disperse toward the evaporation region SR. This prevents the working fluid 2b from freezing unevenly toward the condensation region CR, and prevents the vapor flow path 50 from being blocked by frozen working fluid 2b. In this way, performance degradation of the vapor chamber 1 can be effectively prevented.

Furthermore, according to this embodiment, the multiple frame protrusions 70 include second protrusions 72 provided on a pair of inner end portions 32b extending in the Y direction. This allows the working fluid 2b to wet, spread, and disperse in the Y direction as well. This further prevents the vapor flow path portion 50 from being blocked by frozen working fluid 2b.

Furthermore, according to this embodiment, when viewed in a cross section along the Z direction, the frame protrusion 70 has a lower curved surface 70d provided on one side in the Z direction and an upper curved surface 70e provided on the other side in the Z direction. As such, the frame protrusion 70 has multiple curved surfaces, which further increases the contact area between the working fluid 2b and the frame portion 32, allowing the working fluid 2b to further spread across the frame portion 32. This further prevents the vapor flow path 50 from being blocked by frozen working fluid 2b.

Furthermore, according to this embodiment, when viewed in a cross section along the Z direction, the protrusion 70c is positioned further inward in the first vapor passage 51 than the lower end 70a, and further inward in the first vapor passage 51 than the upper end 70b. Such protrusion 70c can be formed by etching from the first body surface 31a and the second body surface 31b in an etching process. Etching from the first body surface 31a and etching from the second body surface 31b can be performed simultaneously. This allows the number of etching processes to be reduced, improving the manufacturing efficiency of the vapor chamber 1.

Furthermore, according to this embodiment, working fluids 2a and 2b that are expandable upon freezing are sealed in the vapor chamber 1. If the working fluids 2a and 2b that are expandable upon freezing freeze within the vapor flow path portion 50, the force caused by their expansion may be felt by the lower sheet 10 and the upper sheet 20, causing deformation of the vapor chamber 1. In contrast, according to this embodiment, the working fluid 2b can be spread and dispersed by wetting at the inner ends 32a and 32b of the frame portion 32. As a result, even if the working fluid 2b expands upon freezing, the force caused by that expansion can be prevented from acting on the lower sheet 10 and the upper sheet 20. This prevents deformation of the vapor chamber 1.

(First Modification)
In the above-described embodiment, an example has been described in which the frame body protrusions 70 have a rectangular shape in a plan view (see FIGS. 9 and 10 ). However, this is not limited thereto, and the frame body protrusions 70 may have any shape as long as they are formed convexly toward the steam flow path 50. For example, as shown in FIG. 15 , the frame body protrusions 70 may have a triangular shape in a plan view. Furthermore, for example, the frame body protrusions 70 may have a curved shape, such as a semicircular shape, a semielliptical shape, or a wavy shape, in a plan view. FIG. 16 illustrates an example in which the frame body protrusions 70 have a semicircular shape. In such a case, the dimensions of the frame body protrusions 70 may be approximately the same as the dimensions of the frame body protrusions 70 in the above-described embodiment. Furthermore, the arrangement pitch of the frame body protrusions 70 may also be approximately the same as the arrangement pitch of the frame body protrusions 70 in the above-described embodiment.

Even in this first modified example, the frame protrusion 70 increases the contact area between the working fluid 2b and the frame portion 32, allowing the working fluid 2b to spread across the frame portion 32. Therefore, even if the working fluid 2b freezes, the vapor flow path portion 50 can be prevented from being blocked by the frozen working fluid 2b, and performance degradation of the vapor chamber 1 can be suppressed.

(Second Modification)
In the above-described embodiment, an example has been described in which the protrusion 70c of the frame convex portion 70 is positioned more inward (to the right in FIG. 11 ) than the lower end 70a of the first steam passage 51 and more inward than the upper end 70b of the first steam passage 51 (see FIG. 11 ). However, this is not limiting, and the lower end 70a or the upper end 70b may be positioned more inward than the protrusion 70c of the first steam passage 51.

17, the protrusion 70c may protrude closer to the first steam passage 51 than the lower end 70a, and the upper end 70b may be located closer to the first steam passage 51 than the protrusion 70c. In this case, the frame protrusion 70 may be formed by etching only from the first main body surface 31a of the wick sheet 30. For example, the frame protrusion 70 may be formed by performing two etching processes starting from the first main body surface 31a of the wick sheet 30. That is, in the first etching process, a resist film on the first main body surface 31a is patterned to have a shape corresponding to the lower steam passage recess 53, and the first material surface Ma of the metal material sheet M is etched through the opening in the resist film. In the second etching step, a new resist film is formed on the first body surface 31a and the wall surface 53a of the lower steam flow path recess 53. The resist film is then patterned to have a shape corresponding to the upper steam flow path recess 54, and the wall surface 53a of the lower steam flow path recess 53 is etched through the openings in the resist film. In this case, the wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54 join to form the through-hole 34. However, the position where the planar area of the steam flow path section 50 is smallest is not the position of the through-hole 34, but the position where the upper end 70b is located in the Z direction. In this case, the outline of the frame protrusion 70 depicted in Figures 9 and 10 corresponds to the outline of the upper end 70b in a plan view.

18, the protrusion 70c may be positioned further inward in the first steam passage 51 than the upper end 70b, and the lower end 70a may be positioned further inside the first steam passage 51 than the protrusion 70c. In this case, the frame protrusion 70 may be formed by etching only from the second main body surface 31b of the wick sheet 30. For example, the frame protrusion 70 may be formed by performing two etching processes from the second main body surface 31b of the wick sheet 30, as in the example shown in FIG. 17. In this case, the position where the planar area of the steam flow passage section 50 is smallest is not the position of the through-hole 34, but the position where the lower end 70a is located in the Z direction. In this case, the outline of the frame protrusion 70 depicted in FIGS. 9 and 10 corresponds to the outline of the lower end 70a in a plan view.

When the frame protrusion 70 having the shape shown in Figures 17 and 18 is formed by the etching process described above, the wall surface 53a of the lower steam flow path recess 53 and the wall surface 54a of the upper steam flow path recess 54 in areas other than the frame protrusion 70 may also be formed to have a similar shape.

In this second modified example, the frame protrusion 70 also increases the contact area between the working fluid 2b and the frame portion 32, allowing the working fluid 2b to spread across the frame portion 32. Furthermore, according to the second modified example, the amount by which the protrusion 70c protrudes inward into the first vapor passage 51 can be reduced. This allows the width of the first vapor passage 51 at the protrusion 70c to be increased, thereby increasing the space within the first vapor passage 51. Therefore, even if the working fluid 2b freezes, the vapor flow path portion 50 can be further prevented from being blocked by the frozen working fluid 2b, further preventing a decrease in performance of the vapor chamber 1.

The multiple frame body protrusions 70 may also include a frame body protrusion 70 as shown in FIG. 17 and a frame body protrusion 70 as shown in FIG. 18. Here, the frame body protrusion 70 as shown in FIG. 17 will be referred to as an upper end side protrusion 74 (second end side protrusion), and the frame body protrusion 70 as shown in FIG. 18 will be referred to as a lower end side protrusion 73 (first end side protrusion). In this case, in the lower end side protrusion 73, as shown in FIG. 18, the protrusion 70c is positioned more inward in the first steam passage 51 than the upper end 70b, and the lower end 70a is positioned more inward in the first steam passage 51 than the protrusion 70c. As shown in FIG. 17 , in the upper end portion 74, the protrusion 70c is positioned more inward of the first steam passage 51 than the lower end portion 70a, and the upper end portion 70b is positioned more inward of the protrusion 70c. In plan view, the lower end portion 73 and the upper end portion 74 may be arranged alternately. For example, as shown in FIG. 9 , in each inner end portion 32a extending in the X direction, the lower end portion 73 and the upper end portion 74 may be arranged alternately in the X direction. That is, the multiple first protrusions 71 may include lower end portion 73 and upper end portion 74 arranged alternately in the X direction. Furthermore, as shown in FIG. 10 , in each inner end portion 32b extending in the Y direction, the lower end portion 73 and the upper end portion 74 may be arranged alternately in the Y direction. That is, the multiple second protrusions 72 may include lower end protrusions 73 and upper end protrusions 74 arranged alternately in the Y direction.

In this way, by alternately arranging frame protrusions 70 with different shapes in the Z direction, the working fluid 2b can more easily spread across the frame portion 32. Therefore, even if the working fluid 2b freezes, the vapor flow path portion 50 can be more effectively prevented from being blocked by the frozen working fluid 2b, and performance degradation of the vapor chamber 1 can be more effectively prevented.

(Third Modification)
In the above-described embodiment, an example has been described in which the frame protrusions 70 are provided on each of the pair of inner end portions 32 a extending in the X direction and the pair of inner end portions 32 b extending in the Y direction (see FIG. 6 ). However, this is not limiting, and the frame protrusions 70 may be provided on one or more of the inner end portions 32 a, 32 b of the frame portion 32.

For example, the frame protrusion 70 may be provided on one of the pair of inner ends 32a extending in the X direction, and may not be provided on either of the pair of inner ends 32b extending in the Y direction. Also, for example, the frame protrusion 70 may be provided on each of the pair of inner ends 32a extending in the X direction, and may not be provided on either of the pair of inner ends 32b extending in the Y direction. Also, for example, the frame protrusion 70 may be provided on each of the pair of inner ends 32a extending in the X direction, and may be provided on either of the pair of inner ends 32b extending in the Y direction.

Even in this third modified example, the frame protrusion 70 increases the contact area between the working fluid 2b and the frame portion 32, allowing the working fluid 2b to spread across the frame portion 32. Therefore, even if the working fluid 2b freezes, the vapor flow path portion 50 can be prevented from being blocked by the frozen working fluid 2b, and performance degradation of the vapor chamber 1 can be suppressed.

(Fourth Modification)
In the above-described embodiment, an example has been described in which the frame protrusions 70 are arranged around the entire periphery of the inner ends 32a, 32b of the frame portion 32 in a plan view (see FIG. 6 ). However, this is not limiting, and the frame protrusions 70 may be arranged only in a partial region of the inner ends 32a, 32b of the frame portion 32. The frame protrusions 70 may not be arranged in other regions.

For example, as shown in FIG. 19 , the frame protrusion 70 may be provided in the condensation region CR. That is, if the evaporation region SR is provided on one side of the vapor chamber 1 in the X direction (the left side in FIG. 19 ), the frame protrusion 70 may be provided only on the other side of the vapor chamber 1 in the X direction (the right side in FIG. 19 ). More specifically, the frame protrusion 70 may be provided on the portion of the inner end 32a facing the condensation region CR (the right half in FIG. 19 ) and on the condensation region CR side of the pair of inner end portions 32b (the right side in FIG. 19 ), but may not be provided on the portion of the inner end 32a facing the evaporation region SR (the left half in FIG. 19 ) and on the evaporation region SR side of the pair of inner end portions 32b (the left side in FIG. 19 ).

As described above, the working fluid 2b is generated in the condensation region CR and evaporated in the evaporation region SR.
Therefore, the working fluid 2b is particularly likely to adhere to the inner end portions 32a, 32b of the frame portion 32 on the condensation region CR side rather than the evaporation region SR side. By providing the frame protrusions 70 closer to the condensation region CR than the evaporation region SR side as in the fourth modification, the working fluid 2b adhering to the condensation region CR side can be allowed to wet and spread toward the evaporation region SR side. This prevents the working fluid 2b from freezing unevenly toward the condensation region CR side, and prevents the frozen working fluid 2b from blocking the vapor flow path portion 50. As a result, performance degradation of the vapor chamber 1 can be effectively suppressed. Furthermore, by limiting the provision of the frame protrusions 70 on the evaporation region SR side, the flow of the working vapor 2a on the evaporation region SR side can be smoothed. That is, the working vapor 2a can be smoothly transported from the evaporation region SR to the condensation region CR. This prevents performance degradation of the vapor chamber 1. Furthermore, by limiting the provision of the frame protrusions 70, the vapor chamber 1 can be easily manufactured. Therefore, the manufacturing cost of the vapor chamber 1 can be prevented from increasing.

The present invention is not limited to the above-described embodiment and each modification, and in the implementation stage, the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining the multiple components disclosed in the above-described embodiment and each modification. Some components may be omitted from all of the components shown in the above-described embodiment and each modification.

1 Vapor chamber 2a Working vapor 2b Working liquid 10 Lower sheet 20 Upper sheet 30 Wick sheet 32 Frame body portion 33 Land portion 50 Vapor flow path portion 60 Liquid flow path portion 70 Frame body convex portion 70a Lower end portion 70b Upper end portion 70c Protrusion portion 70d Lower curved surface 70e Upper curved surface 71 First convex portion 72 Second convex portion 73 Lower end side convex portion 74 Upper end side convex portion SR Evaporation region CR Condensation region D Device E Electronic device H Housing

Claims (11)

A wick sheet for a vapor chamber used in a vapor chamber in which a working fluid is sealed in a sealed space ,
a frame portion defining the sealed space ;
a land portion provided within the frame portion;
a vapor flow path portion provided between the frame portion and the land portion, through which vapor of the working fluid passes;
a liquid flow path portion provided in the land portion, communicating with the vapor flow path portion, through which the liquid working fluid passes,
the frame portion has a frame protrusion formed in a convex shape toward the inside of the steam flow path portion in a plan view,
the frame protrusion faces the land portion,
A wick sheet for a vapor chamber, wherein, in a plan view, the width of the vapor flow path portion at a position where the frame body convex portion is not present is greater than the width of the vapor flow path portion at a position where the frame body convex portion is present. A wick sheet for a vapor chamber used in a vapor chamber in which a working fluid is sealed in a sealed space ,
a frame portion defining the sealed space ;
a land portion provided within the frame portion;
a vapor flow path portion provided between the frame portion and the land portion, through which vapor of the working fluid passes;
a liquid flow path portion provided in the land portion, communicating with the vapor flow path portion, through which the liquid working fluid passes,
the frame portion has a frame protrusion formed in a convex shape toward the inside of the steam flow path portion in a plan view,
A wick sheet for a vapor chamber, wherein the frame protrusion is arranged in a partial area of the frame. A wick sheet for a vapor chamber used in a vapor chamber in which a working fluid is sealed in a sealed space ,
a frame portion defining the sealed space ;
a land portion provided within the frame portion;
a seat space provided between the frame portion and the land portion;
a groove portion provided in the land portion and communicating with the seat space,
the frame portion has a frame protrusion formed in a convex shape toward the seat space in a plan view,
the frame protrusion faces the land portion,
A wick sheet for a vapor chamber, wherein, in a plan view, the width of the sheet space at a position where the frame protrusion is not present is greater than the width of the sheet space at a position where the frame protrusion is present. A wick sheet for a vapor chamber used in a vapor chamber in which a working fluid is sealed in a sealed space ,
a frame portion defining the sealed space ;
a land portion provided within the frame portion;
a seat space provided between the frame portion and the land portion;
a groove portion provided in the land portion and communicating with the seat space,
the frame portion has a frame protrusion formed in a convex shape toward the seat space in a plan view,
A wick sheet for a vapor chamber, wherein the frame protrusion is arranged in a partial area of the frame. A wick sheet for a vapor chamber according to claim 1 or 2, wherein, when viewed in a cross section along the thickness direction of the wick sheet, the frame convex portion has a first curved surface provided on one side in the thickness direction, a second curved surface provided on the other side in the thickness direction, and a protrusion where the first curved surface and the second curved surface join together and protrude into the vapor flow path portion. A wick sheet for a vapor chamber according to claim 3 or 4, wherein, when viewed in a cross section along the thickness direction of the wick sheet, the frame convex portion has a first curved surface provided on one side in the thickness direction, a second curved surface provided on the other side in the thickness direction, and a protrusion where the first curved surface and the second curved surface join together and protrude into the sheet space. a condensation region in which the working fluid condenses;
an evaporation region in which the working fluid evaporates;
The wick sheet for a vapor chamber according to claim 1 , wherein the frame protrusion is provided in the condensation region. A wick sheet for a vapor chamber according to any one of claims 1 to 7, wherein the land portion has a longitudinal direction aligned with the first direction. A wick sheet for a vapor chamber according to any one of claims 1 to 8, wherein the frame protrusion has a rectangular, triangular, or curved shape in a plan view. A vapor chamber comprising a wick sheet for a vapor chamber according to any one of claims 1 to 9. An electronic device equipped with the vapor chamber described in claim 10.