JP2026016727A - Vapor chamber, wick sheet for vapor chamber, and electronic device - Google Patents

Abstract

A vapor chamber with excellent cooling capacity, a wick sheet for the vapor chamber, and an electronic device equipped with the vapor chamber and the wick sheet are provided.
[Solution] The vapor chamber (1) includes a first sheet (10), a second sheet (20), and a wick sheet (30). The wick sheet (30) has a first body surface (31a), a second body surface (31b), a vapor flow path section (50) extending from the first body surface (31a) to the second body surface (31b) and through which vapor of the working fluid passes, and a liquid flow path section (60) provided on the second body surface (31b) and communicating with the vapor flow path section (50) and through which liquid working fluid passes. The liquid flow path section (60) has a plurality of liquid flow path mainstream grooves (61a-61f) through which the liquid working fluid passes, and of the plurality of liquid flow path mainstream grooves (61a-61f), the width of the liquid flow path mainstream grooves (61a, 61f) closest to the vapor flow path section (50) is wider than the widths of the other liquid flow path mainstream grooves (61b-61e).
[Selected figure] Figure 8

Description

This disclosure relates to vapor chambers, wick sheets for vapor chambers, and electronic devices.

Central processing units (CPUs), light-emitting diodes (LEDs), power semiconductors, and other devices used in mobile devices such as handheld devices and tablet computers are devices that generate heat. These devices are cooled by heat dissipation components such as heat pipes. In recent years, thinner heat dissipation components have been required to make mobile devices thinner. For this reason, vapor chambers, which can be made thinner than heat pipes, have been developed. A working fluid is sealed inside the vapor chamber. This working fluid absorbs and dissipates the heat from the device, thereby cooling it. For example, Patent Document 1 discloses a sheet-type heat pipe made of two or more stacked metal foil sheets.

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 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. 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.

Japanese Patent Application Laid-Open No. 2016-017702

The purpose of this embodiment is to provide a vapor chamber with excellent cooling capacity, a wick sheet for the vapor chamber, and an electronic device equipped with these.

The vapor chamber according to this embodiment is a vapor chamber in which a working fluid is sealed, and includes a first sheet, a second sheet, and a wick sheet interposed between the first and second sheets. The wick sheet has a first body surface, a second body surface located opposite the first body surface, a vapor flow path section extending from the first body surface to the second body surface and through which vapor of the working fluid passes, and a liquid flow path section provided on the second body surface and communicating with the vapor flow path section and through which the liquid working fluid passes. The liquid flow path section has a plurality of liquid flow path mainstream grooves arranged parallel to each other and through which the liquid working fluid passes, and the width of the liquid flow path mainstream groove closest to the vapor flow path section is wider than the width of the other liquid flow path mainstream grooves.

In the vapor chamber according to this embodiment, the width of the liquid flow path mainstream groove closest to the vapor flow path portion may be 1.1 to 1.6 times the width of the other liquid flow path mainstream groove.

In the vapor chamber according to this embodiment, the depth of the liquid flow path mainstream groove closest to the vapor flow path portion may be deeper than the depth of the other liquid flow path mainstream grooves.

In the vapor chamber according to this embodiment, the center-to-center distances in the width direction of the multiple liquid flow path mainstream grooves may be equal to each other.

In the vapor chamber according to this embodiment, rows of convex portions are provided between adjacent main liquid flow channel grooves, each row of convex portions having a plurality of convex portions, and the arrangement pitch of the convex portions in the longitudinal direction of the main liquid flow channel groove may be uniform between the convex portions.

In the vapor chamber according to this embodiment, the widths of the multiple liquid flow path mainstream grooves may gradually narrow from the liquid flow path mainstream groove closest to the vapor flow path section toward the liquid flow path mainstream groove located inward in the width direction of the liquid flow path section.

The wick sheet according to this embodiment is a wick sheet for a vapor chamber, and has a first main body surface, a second main body surface located opposite the first main body surface, a vapor flow path section extending from the first main body surface to the second main body surface and through which vapor of the working fluid passes, and a liquid flow path section provided on the second main body surface and communicating with the vapor flow path section and through which the liquid working fluid passes, the liquid flow path section having a plurality of liquid flow path mainstream grooves arranged parallel to each other and through which the liquid working fluid passes, and of the plurality of liquid flow path mainstream grooves, the width of the liquid flow path mainstream groove closest to the vapor flow path section is wider than the width of the other liquid flow path mainstream grooves.

In the wick sheet according to this embodiment, the width of the liquid flow path mainstream groove closest to the vapor flow path portion may be 1.1 to 1.6 times the width of the other liquid flow path mainstream groove.

In the wick sheet according to this embodiment, the depth of the liquid flow path mainstream groove closest to the vapor flow path portion may be deeper than the depth of the other liquid flow path mainstream grooves.

In the wick sheet according to this embodiment, the center-to-center distances in the width direction of the multiple liquid flow path mainstream grooves may be equal to each other.

In the wick sheet according to this embodiment, rows of convex portions are provided between adjacent main liquid flow channel grooves, each row of convex portions having a plurality of convex portions, and the arrangement pitch of the convex portions in the longitudinal direction of the main liquid flow channel groove may be uniform between the convex portions.

In the wick sheet according to this embodiment, the widths of the multiple liquid flow path mainstream grooves may gradually narrow from the liquid flow path mainstream groove closest to the vapor flow path section toward the liquid flow path mainstream groove located inside the liquid flow path section in the width direction.

The electronic device according to this embodiment includes a housing, a device housed within the housing, and a vapor chamber according to this embodiment in thermal contact with the device.

Embodiments of the present disclosure can provide a vapor chamber with excellent cooling capacity.

The vapor chamber according to this embodiment is a vapor chamber in which a working fluid is sealed, and includes a first sheet, a second sheet, and a wick sheet interposed between the first and second sheets. The wick sheet has a first body surface, a second body surface opposite the first body surface, a vapor flow path section extending from the first body surface to the second body surface and through which vapor of the working fluid passes, and a liquid flow path section provided on the second body surface and communicating with the vapor flow path section and through which the liquid working fluid passes. The liquid flow path section has a plurality of liquid flow path mainstream grooves arranged parallel to each other and through which the liquid working fluid passes. Rows of convex portions are provided between adjacent liquid flow path mainstream grooves, each row having a plurality of convex portions, and the width of the convex portions of the row of convex portions closest to the vapor flow path section is narrower than the width of the convex portions of the other rows of convex portions.

In the vapor chamber according to this embodiment, the width of the convex portions of the convex portion row closest to the vapor flow path portion may be 0.3 to 0.95 times the width of the convex portions of the other convex portion rows.

In the vapor chamber according to this embodiment, the arrangement pitch between the convex portions of the convex portion row closest to the vapor flow path portion and the convex portions of the convex portion row adjacent to that convex portion row may be narrower than the arrangement pitch between the convex portions of the other convex portion rows.

In the vapor chamber according to this embodiment, the widths of the multiple liquid flow path mainstream grooves may be uniform.

In the vapor chamber according to this embodiment, the width of the liquid flow path mainstream groove closest to the vapor flow path portion among the plurality of liquid flow path mainstream grooves may be wider than the width of the other liquid flow path mainstream grooves.

In the vapor chamber according to this embodiment, the width of the plurality of protrusions may gradually increase from the protrusions in the row of protrusions closest to the vapor flow path section toward the protrusions in the row of protrusions located inward in the width direction of the liquid flow path section.

The wick sheet according to this embodiment is a wick sheet for a vapor chamber, and has a first body surface, a second body surface located opposite the first body surface, a vapor flow path section extending from the first body surface to the second body surface and through which vapor of the working fluid passes, and a liquid flow path section provided on the second body surface and communicating with the vapor flow path section and through which the liquid working fluid passes. The liquid flow path section has a plurality of liquid flow path mainstream grooves arranged parallel to each other and through which the liquid working fluid passes. Rows of convex portions are provided between adjacent liquid flow path mainstream grooves, each row having a plurality of convex portions, and the width of the convex portions of the row of convex portions closest to the vapor flow path section is narrower than the width of the convex portions of the other rows of convex portions.

In the wick sheet according to this embodiment, the width of the convex portions of the convex portion row closest to the steam flow path portion may be 0.3 to 0.95 times the width of the convex portions of the other convex portion rows.

In the wick sheet according to this embodiment, the arrangement pitch between the convex portions of the convex portion row closest to the steam flow path portion and the convex portions of the convex portion row adjacent to that convex portion row may be narrower than the arrangement pitch between the convex portions of the other convex portion rows.

In the wick sheet according to this embodiment, the widths of the multiple liquid flow path main grooves may be uniform.

In the wick sheet according to this embodiment, the width of the liquid flow path mainstream groove closest to the vapor flow path section among the plurality of liquid flow path mainstream grooves may be wider than the width of the other liquid flow path mainstream grooves.

In the wick sheet according to this embodiment, the width of the plurality of protrusions may gradually increase from the protrusions in the row of protrusions closest to the steam flow path section toward the protrusions in the row of protrusions located inside the liquid flow path section in the width direction.

The electronic device according to this embodiment includes a housing, a device housed within the housing, and a vapor chamber according to this embodiment in thermal contact with the device.

Embodiments of the present disclosure can increase the cooling capacity of the vapor chamber.

FIG. 1 is a schematic perspective view illustrating an electronic device according to a first embodiment. FIG. 2 is a top view showing the vapor chamber according to the first embodiment. FIG. 3 is a cross-sectional view of the vapor chamber taken along line III-III 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 a bottom view of the wick sheet of FIG. FIG. 8 is an enlarged cross-sectional view of a portion of FIG. FIG. 9 is a partially enlarged top view of the liquid flow path portion shown in FIG. 10(a) to 10(c) are diagrams illustrating a method for manufacturing a vapor chamber according to the first embodiment. FIG. 11 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a first modification of the first embodiment. FIG. 12 is a partially enlarged top view showing a liquid flow path portion according to a first modification of the first embodiment. FIG. 13 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a second modification of the first embodiment. FIG. 14 is a partially enlarged top view showing a liquid flow path portion according to a second modification of the first embodiment. FIG. 15 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a third modification of the first embodiment. FIG. 16 is a partially enlarged top view showing a liquid flow path portion according to a third modified example of the first embodiment. FIG. 17 is a partially enlarged top view showing a liquid flow path portion according to a fourth modification of the first embodiment. FIG. 18 is a partially enlarged cross-sectional view of the vapor chamber according to the second embodiment. FIG. 19 is a partially enlarged top view of a liquid flow path portion of a wick sheet according to the second embodiment. FIG. 20 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a first modification of the second embodiment. FIG. 21 is a partially enlarged top view showing a liquid flow path portion according to a first modified example of the second embodiment. FIG. 22 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a second modification of the second embodiment. FIG. 23 is a partially enlarged top view showing a liquid flow path portion according to a second modification of the second embodiment. FIG. 24 is a partially enlarged cross-sectional view showing a liquid flow path portion according to a third modification of the second embodiment. FIG. 25 is a partially enlarged top view showing a liquid flow path portion according to a third modified example of the second embodiment. FIG. 26 is a partially enlarged top view showing a liquid flow path portion according to a fourth modification of the second embodiment.

(First embodiment)
The first embodiment will be described below with reference to Figures 1 to 17. In the drawings attached to this specification, the scale and aspect ratios have been appropriately changed 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 values of lengths, angles, and physical characteristics, are not bound by strict meanings. These terms and numerical values should be interpreted to include the range of degrees to which similar functions can be expected. Furthermore, in the drawings, for clarity, the shapes of multiple parts that can be expected to have similar functions are depicted in a regular pattern. However, without being bound by strict meanings, the shapes of these parts may differ from each other as long as the function can be expected. In the drawings, boundary lines indicating the joining surfaces between components are shown as simple straight lines for convenience. Boundaries are not required to be strictly straight lines. The shape of the boundary line is arbitrary as long as the desired joining performance can be expected.

The vapor chamber, wick sheet for the vapor chamber, and electronic device of this embodiment will be described using Figures 1 to 10. The vapor chamber 1 of this embodiment is a device mounted on electronic device E to cool device D, which is a heat-generating body housed in the electronic device E. Examples of device D include electronic devices that generate heat (cooled devices) used in mobile devices such as portable terminals and tablet terminals. Examples of electronic devices that generate heat include central processing units (CPUs), light-emitting diodes (LEDs), power semiconductors, and other electronic devices that generate heat (cooled 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 (e.g., a 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 in which working fluids 2a and 2b are sealed. The vapor chamber 1 is configured to effectively cool the device D of the electronic device E described above by repeatedly changing the phases of the working fluids 2a and 2b in the sealed space 3. Examples of working fluids 2a and 2b include pure water, ethanol, methanol, acetone, etc., and mixtures thereof. Note that the working fluids 2a and 2b may 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). The wick sheet 30 is 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 FIG. 2. The planar shape of the vapor chamber 1 may be, for example, a rectangle with one side measuring 50 mm to 200 mm and the other side measuring 150 mm to 60 mm, or a square with one side measuring 70 mm to 300 mm. The planar dimensions of the vapor chamber 1 are arbitrary. In this embodiment, as an example, the planar shape of the vapor chamber 1 is described as a rectangle with the X-direction (described below) as its longitudinal direction. In this case, as shown in FIGS. 4 to 7, 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. 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. Therefore, the evaporation region SR includes the region that overlaps with the device D and the surrounding area in a planar view. Here, the planar view refers to the state when the vapor chamber 1 is viewed 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). That is, a plan view corresponds to a state in which the vapor chamber 1 is viewed from above or below, as shown in Figure 2, for example.

The condensation region CR is a region that does not overlap with the device D in a plan view, and is the region where the working vapor 2a primarily releases heat and condenses. The condensation region CR can also be described as the region surrounding the evaporation region SR. 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 located opposite the wick sheet 30, and a second lower sheet surface 10b located 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 the housing 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 located 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 includes a vapor flow path section 50 and a liquid flow path section 60 disposed adjacent to the vapor flow path section 50. The wick sheet 30 also includes a first main body surface 31a and a second main body surface 31b located on the opposite side of the first main body surface 31a. The first main body surface 31a is disposed on the side of the lower sheet 10, and the second main 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 wick sheet 30 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 wick sheet 30 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. "Permanently bonded" means that the lower sheet 10 and wick sheet 30 are bonded to a degree that allows the lower sheet 10 and wick sheet 30 to maintain their bond, and the upper sheet 20 and wick sheet 30 to maintain their bond, to a degree that allows the sealed space 3 to be maintained in its sealed state during operation of the vapor chamber 1.

As shown in Figures 3, 6, and 7, the wick sheet 30 according to this embodiment has a frame portion 32 formed in a rectangular frame shape in plan view, and a land portion 33 provided within the frame portion 32. The frame portion 32 and the land portion 33 are portions that 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 in a rectangular frame shape in plan view. A steam flow path portion 50 is defined inside the frame portion 32. In other words, the working steam 2a flows inside the frame portion 32 and around the land portion 33.

In this embodiment, the land portion 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. The planar shape of the land portion 33 may be an elongated rectangle. Furthermore, each land portion 33 may be arranged parallel to one another and equally spaced apart 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 of the land portion 33 (see FIG. 8) may be, for example, 30 μm or more and 3000 μm or less. Here, the width w1 of the land portion 33 refers to the dimension of the land portion 33 in the Y direction, and refers to the dimension at the widest position of the land portion 33 (for example, the position where the protrusion 55 described below is present).

The frame body 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 first wall surface 53a and second wall surface 54a of the vapor passage 51 (described below) form the side walls of the land portion 33. The first main body surface 31a and second main body surface 31b of the wick sheet 30 may be formed flat across the frame body 32 and each land portion 33.

The vapor flow path section 50 is a flow path through which the vapor of the working fluid (referred to as working vapor 2a where appropriate) passes. The vapor flow path section 50 extends from the first main body surface 31a to the second main body surface 31b and penetrates the wick sheet 30.

As shown in Figures 6 and 7, the steam flow path section 50 in this embodiment has multiple steam passages 51. Each steam passage 51 is formed inside the frame body section 32 and outside the land section 33. That is, the steam passages 51 are formed between the frame body section 32 and the land section 33, and between adjacent land sections 33. The planar shape of each steam passage 51 is an elongated rectangle. The multiple land sections 33 divide the steam flow path section 50 into multiple steam passages 51.

As shown in Figure 3, the steam passage 51 is formed to extend from the first main body surface 31a to the second main body surface 31b of the wick sheet 30.

The steam passage 51 may be formed by etching the first and second body surfaces 31a and 31b of the wick sheet 30, respectively, in an etching process described below. In this case, as shown in FIG. 8, the steam passage 51 has a curved first wall surface 53a and a curved second wall surface 54a. The first wall surface 53a is located on the first body surface 31a side and curves in a shape that bulges toward the second body surface 31b. The second wall surface 54a is located on the second body surface 31b side and curves in a shape that bulges toward the first body surface 31a. The first and second wall surfaces 53a and 54a meet at a protrusion 55 formed to jut inward from the steam passage 51. The protrusion 55 may be formed at an acute angle in cross-section. The planar area of the steam passage 51 is minimized at the location of the protrusion 55. The width w2 of the steam passage 51 (see FIG. 8) may be, for example, 100 μm or more, or 400 μm or more. The width w2 of the steam passage 51 may be 5000 μm or less, or 1600 μm or less. Here, the width w2 of the steam passage 51 refers to the width at the narrowest portion of the steam passage 51, and in this case refers to the distance measured in the width direction (Y direction) at the position where the protrusion 55 is located. The width w2 of the steam passage 51 also corresponds to the gap between adjacent land portions 33 in the width direction (Y direction).

The position of the protrusion 55 in the thickness direction (Z direction) of the wick sheet 30 is shifted toward the second body surface 31b from the midpoint between the first body surface 31a and the second body surface 31b. When the distance between the protrusion 55 and the second body surface 31b is t5, the distance t5 may be 5% or more, 10% or more, or 20% or more of the thickness t4 of the wick sheet 30 (described below), or may be 50% or less, 40% or less, or 30% or less of the thickness t4 of the wick sheet 30. However, the position of the protrusion 55 in the thickness direction (Z direction) of the wick sheet 30 may be midpoint between the first body surface 31a and the second body surface 31b, or may be shifted toward the first body surface 31a from the midpoint. The position of the protrusion 55 is arbitrary as long as the steam passage 51 penetrates the wick sheet 30 in the thickness direction (Z direction).

In addition, in this embodiment, the cross-sectional shape of the steam passage 51 is defined by the protrusion 55 formed to protrude inward, but this is not limited to this. For example, the cross-sectional shape of the steam passage 51 may be trapezoidal, rectangular, or barrel-shaped.

The steam flow path section 50, including the steam passages 51 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 wick sheet 30 described above. Each steam passage 51 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 steam passages 51 and other components enlarged, and the number and arrangement of these steam passages 51 and other components differ from those in Figures 2, 6, and 7.

As shown in Figures 6 and 7, support portions 39 that support the land portions 33 on the frame portion 32 are provided within the steam flow path portion 50. The support portions 39 support adjacent land portions 33. The support portions 39 are provided on both sides of the land portions 33 in the longitudinal direction (X direction). The support portions 39 are preferably formed so as not to interfere with the flow of working steam 2a diffusing through the steam flow path portion 50. In this case, the support portions 39 are arranged on the first body surface 31a side of the wick sheet 30, and a space communicating with the steam flow path portion 50 is formed on the second body surface 31b side. This allows the thickness of the support portions 39 to be thinner than the thickness of the wick sheet 30, preventing the steam passage 51 from being divided in the X and Y directions. However, this is not limited to this, and the support portions 39 may also be arranged on the second body surface 31b side. Furthermore, spaces communicating with the steam flow path section 50 may be formed on both the surface of the support section 39 facing the first main body surface 31a and the surface of the support section 39 facing the second main body surface 31b.

As shown in Figures 6 and 7, alignment holes 35 may be provided at the four corners of the wick sheet 30.

As shown in FIG. 2, the vapor chamber 1 may further include an injection section 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 section 4 is located on the evaporation region SR side. The injection section 4 has an injection flow path 37 formed in the wick sheet 30. This injection flow path 37 is formed on the second main body surface 31b side of the wick sheet 30 and is recessed from the second main body surface 31b side. After the vapor chamber 1 is completed, the injection flow path 37 is sealed. 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.

In this embodiment, the injection part 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 part 4 can be provided in any position. The injection part 4 may also be formed in advance so as to protrude from one edge in the X direction of the vapor chamber 1.

As shown in Figures 3, 6, and 8, the liquid flow path section 60 is provided on the second main body surface 31b of the wick sheet 30. The working fluid 2b mainly flows through the liquid flow path section 60. This liquid flow path section 60 constitutes part of the sealed space 3 described above and is connected to the vapor flow path section 50. The liquid flow path section 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 section 60 is provided on the second main body surface 31b of each land portion 33 of the wick sheet 30. The liquid flow path section 60 may be formed over the entire second main body surface 31b of each land portion 33.

As shown in FIG. 9, the liquid flow path section 60 has multiple liquid flow path mainstream grooves 61a-61f, through which the hydraulic fluid 2b passes, arranged parallel to one another, and multiple liquid flow path communication grooves 65, which communicate with the liquid flow path mainstream grooves 61a-61f. In the example shown in FIG. 9, each land portion 33 includes six liquid flow path mainstream grooves 61a-61f, but this is not limited to this. The number of liquid flow path mainstream grooves included in each land portion 33 is arbitrary, and may be, for example, between three and 20.

As shown in FIG. 9, each of the liquid flow path main grooves 61a-61f is formed to extend along the longitudinal direction (X direction) of the land portion 33. The multiple liquid flow path main grooves 61a-61f are arranged parallel to one another. Note that if the land portion 33 is curved in plan view, each of the liquid flow path main grooves 61a-61f may extend in a curved manner along the curved direction of the land portion 33. In other words, each of the liquid flow path main grooves 61a-61f does not necessarily have to be formed linearly, and does not necessarily have to extend parallel to the X direction.

The liquid flow path mainstream grooves 61a-61f have a smaller flow path cross-sectional area than the steam passages 51 of the steam flow path section 50, allowing the working fluid 2b to flow primarily by capillary action. The liquid flow path mainstream grooves 61a-61f are configured to transport the working fluid 2b condensed from the working vapor 2a to the evaporation region SR. The liquid flow path mainstream grooves 61a-61f are arranged at intervals from each other in the width direction (Y direction).

The liquid flow path mainstream grooves 61a-61f are formed by etching from the second main body surface 31b of the wick sheet 30 in an etching process described below. As shown in FIG. 8, the liquid flow path mainstream grooves 61a-61f have curved wall surfaces 62. These wall surfaces 62 define the liquid flow path mainstream grooves 61a-61f and are curved in a shape that bulges toward the first main body surface 31a. In the cross section shown in FIG. 8, the radius of curvature of each wall surface 62 is preferably smaller than the radius of curvature of the second wall surface 54a of the steam passage 51.

As shown in FIG. 9, the widths of the liquid flow path mainstream grooves 61a-61f are not all uniform among the liquid flow path mainstream grooves 61a-61f. The widths of the two liquid flow path mainstream grooves 61a, 61f (hereinafter also referred to as liquid flow path mainstream grooves 61a, 61f) closest to the vapor flow path section 50 (vapor passage 51) are wider than the widths of the other liquid flow path mainstream grooves 61b-61e (hereinafter also referred to as liquid flow path mainstream grooves 61b-61e). In other words, when the widths of the liquid flow path mainstream grooves 61a-61f are w3a-w3f, respectively, the widths w3a, w3f of the liquid flow path mainstream grooves 61a, 61f are wider than the widths w3b-w3e of the liquid flow path mainstream grooves 61b-61e (w3a, w3f > w3b-w3e).

In FIG. 9, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the outer side of each liquid flow path section 60 in the width direction are equal to each other, and the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the inner side of each liquid flow path section 60 in the width direction are equal to each other. That is, the relationship w3a = w3f > w3b = w3c = w3d = w3e holds. In this case, the cross-sectional shapes (depth, width, etc.) of the multiple liquid flow path mainstream grooves 61a to 61f may be symmetrical about the center of the land section 33 in the width direction (Y direction). However, this is not a limitation, and the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f may be different from each other. Furthermore, the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e may be different from each other. However, it is preferable that the narrower of the widths w3a and w3f of the liquid flow path main grooves 61a and 61f is wider than the widest of the widths w3b to w3e of the liquid flow path main grooves 61b to 61e.

The widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f are preferably 1.1 to 1.6 times the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e. A ratio of 1.1 or more enhances the capillary force in the centrally located liquid flow path mainstream grooves 61b to 61e, facilitating the transport of the working fluid 2b toward the evaporation region SR. Furthermore, by widening the liquid flow path mainstream grooves 61a and 61f located on the outer width sides of each liquid flow path section 60, a large amount of working fluid 2b can be transported toward the evaporation region SR. Furthermore, when the flow of working fluid 2b to the liquid flow path mainstream grooves 61b to 61e located on the inner width sides of each liquid flow path section 60 is impeded, condensation of working fluid 2b from the vapor flow path section 50 is less likely to be impeded. On the other hand, a ratio of 1.6 or less suppresses a decrease in the amount of working fluid 2b transported through the liquid flow path mainstream grooves 61b to 61e located on the inner width sides of each liquid flow path section 60. It is also possible to prevent a decrease in the capillary force of the liquid flow path mainstream grooves 61a, 61f located on the widthwise outer side of each liquid flow path section 60. Furthermore, it is possible to make it easier for the working fluid 2b to flow from the liquid flow path mainstream grooves 61a, 61f located on the widthwise outer side of each liquid flow path section 60 to the liquid flow path mainstream grooves 61b-61e located on the widthwise inner side.

The widths w3a to w3f of the liquid flow path mainstream grooves 61a to 61f refer to the length in the direction perpendicular to the longitudinal direction of the land portion 33, which in this case is the dimension in the Y direction. The widths w3a to w3f of the liquid flow path mainstream grooves 61a to 61f refer to the dimensions at the second main body surface 31b. The widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the outer side of each liquid flow path section 60 in the width direction may be, for example, 5.5 μm or more and 320 μm or less. The widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the inner side of each liquid flow path section 60 in the width direction may be, for example, 2.2 μm or more and 290 μm or less.

Furthermore, as shown in FIG. 8, the depths h1a and h1b of the liquid flow path mainstream grooves 61a-61f do not have to be uniform across all of the liquid flow path mainstream grooves 61a-61f. Specifically, the depth h1a of the liquid flow path mainstream grooves 61a and 61f located on the outer side of each liquid flow path section 60 in the width direction may be deeper than the depth h1b of the liquid flow path mainstream grooves 61b-61e located on the inner side in the width direction (h1a > h1b). In this case, the depths h1a of the liquid flow path mainstream grooves 61a and 61f are equal to each other, and the depths h1b of the liquid flow path mainstream grooves 61b-61e are equal to each other. However, this is not a limitation, and the depths h1a of the liquid flow path mainstream grooves 61a and 61f may be different from each other. Furthermore, the depths h1b of the liquid flow path mainstream grooves 61b-61e may be different from each other. The depth h1a of the liquid flow path main grooves 61a, 61f may be, for example, 3.5 μm or more and 240 μm or less. The depth h1b of the liquid flow path main grooves 61b-61e may be, for example, 3 μm or more and 200 μm or less.

The depths h1a and h1b of the liquid flow path mainstream grooves 61a to 61f are the distances measured from the second main body surface 31b in a direction perpendicular to the second main body surface 31b, which in this case are the dimensions in the Z direction. Furthermore, the depths h1a and h1b refer to the depths at the deepest points of the liquid flow path mainstream grooves 61a to 61f.

As shown in FIG. 9 , 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 61a-61f. Some liquid flow path communication grooves 65 are arranged to connect adjacent liquid flow path mainstream grooves 61a-61f. Other liquid flow path communication grooves 65 are arranged to connect the steam flow path section 50 (steam passage 51) to the liquid flow path mainstream grooves 61a, 61f closest to the steam flow path section 50. In other words, the liquid flow path communication groove 65 extends from the end side of the land portion 33 in the Y direction to the liquid flow path mainstream grooves 61a, 61f adjacent to that end. In this way, the steam passage 51 of the steam flow path section 50 and the liquid flow path mainstream grooves 61a-61f are connected to each other.

The liquid flow path communication grooves 65 have a smaller flow path cross-sectional area than the steam passages 51 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 longitudinal direction (X direction) of the land section 33.

Like the liquid flow path main grooves 61a-61f, the liquid flow path communication groove 65 is also formed by etching and has wall surfaces (not shown) that are curved in the same manner as the liquid flow path main grooves 61a-61f. As shown in FIG. 9, the width w4 (dimension in the X direction) of the liquid flow path communication groove 65 may be 5 μm or more and 300 μm or less. The depth of the liquid flow path communication groove 65 may be 3 μm or more and 240 μm or less.

The liquid flow path mainstream grooves 61a-61f include liquid flow path intersections 66 that communicate with the liquid flow path communication groove 65. At the liquid flow path intersections 66, the liquid flow path mainstream grooves 61a-61f and the liquid flow path communication groove 65 communicate in a T-shape. In this case, at the liquid flow path intersections 66, one liquid flow path mainstream groove 61a-61f communicates with the liquid flow path communication groove 65 on one side (e.g., the upper side in FIG. 9). This prevents the liquid flow path communication groove 65 on the other side (e.g., the lower side in FIG. 9) from communicating with the liquid flow path mainstream groove 61a-61f at the liquid flow path intersections 66. This prevents the wall surfaces 62 of the liquid flow path mainstream grooves 61a-61f from being cut out on both sides in the Y direction at the liquid flow path intersections 66, leaving one side of the wall surfaces 62 intact. As a result, capillary action can be imparted to the working fluid 2b in the liquid flow path main grooves 61a-61f, even at the liquid flow path intersection 66, preventing a decrease in the driving force of the working fluid 2b toward the evaporation region SR at the liquid flow path intersection 66.

As shown in FIG. 9 , convex portion rows 63 are provided between adjacent liquid flow path mainstream grooves 61a-61f. Each convex portion row 63 includes multiple convex portions 64 (liquid flow path protrusions) arranged in the X direction. The convex portions 64 are provided within the liquid flow path section 60 and protrude from the liquid flow path mainstream grooves 61a-61f and the liquid flow path communication groove 65 to abut against the upper sheet 20. Each convex portion 64 is formed rectangularly so that its longitudinal direction is the X direction in a plan view. The liquid flow path mainstream grooves 61a-61f are arranged between adjacent convex portions 64 in the Y direction. The liquid flow path communication grooves 65 are arranged between adjacent convex portions 64 in the X direction. The liquid flow path communication grooves 65 are formed to extend in the Y direction and connect adjacent liquid flow path mainstream grooves 61a-61f to each other in the Y direction. This allows hydraulic fluid 2b to flow back and forth between these liquid flow path mainstream grooves 61a-61f.

The protrusions 64 are portions that are not etched in the etching process described below, and the material of the wick sheet 30 remains. In this embodiment, as shown in Figure 9, the planar shape of the protrusions 64 (the shape at the position of the second main body surface 31b of the wick sheet 30) is rectangular.

The arrangement pitch of the convex portions 64 in the width direction (Y direction) of the liquid flow path mainstream grooves 61a, 61f is non-uniform among the convex portions 64. That is, the arrangement pitch P1 of the convex portions 64 located on both sides of each liquid flow path mainstream groove 61a, 61f in the width direction (Y direction) may be wider than the arrangement pitch P2 of the convex portions 64 located on both sides of each liquid flow path mainstream groove 61b-61e in the width direction (Y direction) (P1 > P2). The arrangement pitches P1, P2 of the convex portions 64 refer to the distance measured in the Y direction between the center of a convex portion 64 in the Y direction and the center of the convex portion 64 adjacent to it in the X direction. The arrangement pitch P1 of the convex portions 64 located on both sides of the liquid flow path mainstream grooves 61a, 61f in the Y direction may be, for example, 10 μm or more and 820 μm or less. The arrangement pitch P2 of the convex portions 64 located on both sides of the liquid flow path mainstream grooves 61b-61e in the Y direction may be, for example, 9 μm or more and 790 μm or less.

In this embodiment, the convex portions 64 are arranged in a staggered (alternate) pattern. More specifically, the convex portions 64 of convex portion rows 63 adjacent to each other in the Y direction are arranged with a shift relative to each other in the X direction. This shift may be half the arrangement pitch P4 of the convex portions 64 in the longitudinal direction (X direction) of the liquid flow path main grooves 61a-61f. The width w5 of the convex portions 64 (dimension in the Y direction) may be, for example, 5 μm or more and 500 μm or less. Furthermore, the width w5 of the convex portions 64 may be uniform between each pair of convex portions 64. Note that the width w5 of the convex portions 64 refers to the dimension on the second main body surface 31b. The arrangement pitch P4 of the convex portions 64 may be uniform between each pair of convex portions 64. The arrangement pitch P4 of the convex portions 64 is the distance between the X-direction center of a convex portion 64 and the X-direction center of a convex portion 64 adjacent to the X-direction. The arrangement of the protrusions 64 is not limited to a staggered pattern, and they may be arranged in parallel. In this case, the protrusions 64 of the protrusion rows 63 adjacent to each other in the Y direction are also aligned in the X direction (see Figure 17).

The length L1 (dimension in the X direction) of each protrusion 64 may be uniform between each other. Furthermore, the length L1 of each protrusion 64 is longer than the width w4 of the liquid flow path connecting groove 65 (L1 > w4). Note that the length L1 of each protrusion 64 refers to the maximum dimension in the X direction on the second main body surface 31b.

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 or more and 2000 μm or less. By making the thickness t1 of the vapor chamber 1 100 μm or more, the vapor flow path portion 50 can be properly secured, allowing the vapor chamber 1 to function properly. On the other hand, by making the thickness t1 2000 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick.

The thickness t2 of the lower sheet 10 may be, for example, 25 μm or more and 500 μm or less. By making the thickness t2 of the lower sheet 10 25 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 10 500 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 or more and 1000 μm or less. By making the thickness t4 of the wick sheet 30 50 μm or more, the vapor flow path section 50 is properly secured, allowing the vapor chamber 1 to function properly. On the other hand, by making it 1000 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick.

Next, a method for manufacturing the vapor chamber 1 of this embodiment configured as described above will be described using Figures 10(a)-(c). Note that Figures 10(a)-(c) show cross sections similar to the cross-sectional view of Figure 3.

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

First, as shown in Figure 10(a), 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 FIG. 10(b), to form the steam flow path section 50 and the liquid flow path section 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. Subsequently, 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 vapor flow path section 50 and the liquid flow path section 60 as shown in FIG. 10(b). The etching solution may be, for example, an iron chloride-based etching solution such as a ferric chloride aqueous solution, or a copper chloride-based etching solution such as a copper chloride aqueous 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 addition, in the etching process, 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 Figures 6 and 7. In other words, 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 10(c). Note that 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 sheets 10, 20, and 30 are aligned using the alignment holes 12 in the lower sheet 10 (see Figure 4), the alignment holes 35 in the wick sheet 30 (see Figures 6 and 7), and the alignment hole 22 in the upper sheet 20 (see Figure 5).

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

Next, the lower sheet 10, wick sheet 30, and upper sheet 20 are permanently bonded together by diffusion bonding. Diffusion bonding is a bonding method that involves first bringing the lower sheet 10 and wick sheet 30 into close contact with each other, and then bringing the wick sheet 30 and upper sheet 20 into close contact with each other. Next, the lower sheet 10, wick sheet 30, and upper sheet 20 are pressurized and heated in the stacking direction in a controlled atmosphere, such as a vacuum or an inert gas atmosphere, to bond them together by utilizing atomic diffusion that occurs at the bonding surfaces. Diffusion bonding heats the materials of each sheet 10, 20, and 30 to a temperature close to, but lower than, their melting points, preventing melting and deformation of each sheet 10, 20, and 30. 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 to form 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.

After the joining process, hydraulic fluid 2b is injected into the sealed space 3 through the injection section 4.

Then, the injection flow path 37 is sealed. For example, the injection portion 4 may be partially melted to seal the injection flow path 37. This blocks communication between the sealed space 3 and the outside, sealing the hydraulic fluid 2b in the sealed space 3 and preventing the hydraulic fluid 2b in the sealed space 3 from leaking to the outside.

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 an electronic device E, such as a mobile terminal. 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 first wall surface 53a and second wall surface 54a of the vapor passage 51, the wall surface 62 of the liquid flow path main grooves 61a-61f 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 vapor passage 51. 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 vapor passage 51, the liquid flow path main grooves 61a-61f, 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 Figures 6 and 7) 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 vapor passages 51 that form the sealed space 3 (see the solid arrows in Figure 6). The working vapor 2a in each vapor passage 51 leaves the evaporation region SR, and much of the working vapor 2a is transported to the condensation region CR (the right-hand portion in Figures 6 and 7), 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).

The working vapor 2a radiates heat to the lower sheet 10 in the condensation region CR, losing the latent heat it absorbed in the evaporation region SR and condensing to produce working fluid 2b. The produced working fluid 2b adheres to the first wall surface 53a and second wall surface 54a of each steam passage 51, the second lower sheet surface 10b of the lower sheet 10, and the first upper sheet surface 20a of the upper sheet 20. Here, working fluid 2b continues to evaporate in the evaporation region SR. Therefore, working fluid 2b in the liquid flow path section 60 in regions other than 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 61a-61f (see dashed arrows in Figure 6). As a result, the working fluid 2b adhering to each vapor passage 51, second lower sheet surface 10b, and first upper sheet surface 20a moves to the liquid flow path section 60, passes through the liquid flow path communication groove 65, and enters the liquid flow path main grooves 61a-61f. In this way, the working fluid 2b fills each liquid flow path main groove 61a-61f and each liquid flow path communication 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 61a-61f, and is smoothly transported toward the evaporation region SR.

In the liquid flow path section 60, each liquid flow path mainstream groove 61a-61f communicates with adjacent liquid flow path mainstream grooves 61a-61f via the corresponding liquid flow path connection groove 65. This allows working fluid 2b to flow between adjacent liquid flow path mainstream grooves 61a-61f, preventing dryout in the liquid flow path mainstream grooves 61a-61f. This imparts capillary action to the working fluid 2b in each liquid flow path mainstream groove 61a-61f, allowing the working fluid 2b to be smoothly transported 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 vapor paths 51 with large flow path cross-sectional areas, and diffuses within each vapor path 51. In this way, the working fluids 2a and 2b circulate within the sealed space 3 while repeatedly undergoing phase changes, i.e., evaporation and condensation, transporting and releasing heat from the device D. As a result, the device D is cooled.

While the working fluid 2b is transported through the liquid flow path section 60 toward the evaporation region SR, the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61f closest to the vapor flow path section 50 (vapor passage 51) toward the other liquid flow path mainstream grooves 61b-61e may be impeded. In contrast, in this embodiment, the widths w3a, w3f of the liquid flow path mainstream grooves 61a, 61f are wider than the widths w3b-w3e of the liquid flow path mainstream grooves 61b-61e. This allows the condensed working fluid 2b from the vapor flow path section 50 to be stored within the wider liquid flow path mainstream grooves 61a, 61f, even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61f located on the outer side of each liquid flow path section 60 toward the liquid flow path mainstream grooves 61b-61e located on the inner side of each liquid flow path section 60 is impeded. This allows the working fluid 2b to be smoothly condensed from the vapor flow path section 50 toward the liquid flow path section 60. As a result, the pressure difference between the vicinity of the evaporation region SR and the condensation region CR is maintained, preventing a decrease in the cooling capacity of the vapor chamber 1.

In addition, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the widthwise outer sides of each liquid flow path section 60 are wider than the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the widthwise inner sides. This increases the capillary force in the liquid flow path mainstream grooves 61b to 61e located on the widthwise inner sides, making it easier to transport the working fluid 2b toward the evaporation region SR. On the other hand, by widening the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the widthwise outer sides of each liquid flow path section 60, a larger amount of working fluid 2b can be transported toward the evaporation region SR.

As described above, according to this embodiment, the widths w3a, w3f of the liquid flow path mainstream grooves 61a, 61f closest to the vapor flow path section 50 (vapor passage 51) are wider than the widths w3b-w3e of the other liquid flow path mainstream grooves 61b-61e. This allows the working fluid 2b to be stored within the wider liquid flow path mainstream grooves 61a, 61f, even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61f located on the outer side of each liquid flow path section 60 to the liquid flow path mainstream grooves 61b-61e located on the inner side of each liquid flow path section 60 is stagnant. As a result, the working fluid 2b can be smoothly condensed from the vapor flow path section 50 toward the liquid flow path section 60, improving the cooling capacity of the vapor chamber 1.

Furthermore, according to this embodiment, the depth h1a of the liquid flow path mainstream grooves 61a, 61f closest to the vapor flow path section 50 (vapor passage 51) is deeper than the depth h1b of the other liquid flow path mainstream grooves 61b-61e. As a result, even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61f located on the outer side of each liquid flow path section 60 toward the liquid flow path mainstream grooves 61b-61e located on the inner side of each liquid flow path section 60 in the width direction is stagnant, the working fluid 2b can be stored in the deeper liquid flow path mainstream grooves 61a, 61f. This allows the working fluid 2b to condense smoothly from the vapor flow path section 50 toward the liquid flow path section 60, improving the cooling capacity of the vapor chamber 1.

Furthermore, according to this embodiment, the arrangement pitch P1 of the convex portions 64 located on both sides in the width direction of the liquid flow path mainstream grooves 61a, 61f closest to the steam flow path section 50 (steam passage 51) is wider than the arrangement pitch P2 of the convex portions 64 located on both sides in the width direction of the other liquid flow path mainstream grooves 61b-61e. This prevents the width w5 of the convex portions 64 adjacent to the liquid flow path mainstream grooves 61a, 61f from becoming too narrow, thereby preventing a decrease in the bonding strength between the convex portions 64 and the upper sheet 20.

(Modification)
Next, various modified examples of this embodiment will be described with reference to Figures 11 to 17. Figures 11 to 17 are diagrams showing modified wick sheets 30. In Figures 11 to 17, the same parts as those shown in Figures 1 to 10 are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

(First Modification)
In the above-described embodiment, an example has been described in which the width w5 of the convex portions 64 is uniform between the adjacent convex portions 64. However, this is not limited to this, and the width of the convex portions 64 may be non-uniform between the adjacent convex portions 64.

11 and 12, the widths w5a to w5c of the convex portions 64 may be non-uniform between the convex portions 64. For example, the width w5a of the convex portion 64a located on the Y-direction inner side of the liquid flow path main grooves 61a and 61f (toward the liquid flow path main grooves 61b and 61e) may be narrower than the width w5b of the convex portion 64b located further inward in the width direction of each liquid flow path section 60 (w5a < w5b). In this case, the width w5a of the convex portion 64a may be, for example, 5 μm or more and 380 μm or less, and the width w5b of the convex portion 64b may be, for example, 10 μm or more and 400 μm or less. The width w5c of the convex portion 64c located on the outer side in the Y direction (steam flow path section 50 side) of the liquid flow path main grooves 61a, 61f may be the same as the width w5a of the convex portion 64a or the width w5b of the convex portion 64b, or may be different from w5a or w5b.

The center-to-center distance P3 in the width direction (Y direction) of each liquid flow path mainstream groove 61a-61f may also be equal to one another. That is, the distance between liquid flow path mainstream grooves 61a and 61b, the distance between liquid flow path mainstream grooves 61b and 61c, the distance between liquid flow path mainstream grooves 61d and 61e, and the distance between liquid flow path mainstream grooves 61e and 61f are equal to one another. In this case, the center-to-center distance P3 may be, for example, 5 μm or more and 500 μm or less. The center-to-center distance P3 is the shortest distance between the centers of adjacent liquid flow path mainstream grooves 61a-61f in the width direction (Y direction), and is the distance measured in the Y direction.

In this modified example, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the widthwise outer sides of each liquid flow path section 60 are also wider than the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the widthwise inner sides. This allows the working fluid 2b to be stored within the wider liquid flow path mainstream grooves 61a and 61f even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a and 61f located on the widthwise outer sides of each liquid flow path section 60 to the liquid flow path mainstream grooves 61b to 61e located on the widthwise inner sides is stagnant. As a result, the working fluid 2b can be smoothly condensed from the vapor flow path section 50 toward the liquid flow path section 60, improving the cooling capacity of the vapor chamber 1.

(Second Modification)
In the above-described embodiment, an example has been described in which the widths w3a, w3f of the liquid flow path mainstream grooves 61a, 61f located on the outer side in the width direction of each liquid flow path section 60 are equal to each other, and the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the inner side in the width direction are equal to each other. However, this is not limiting, and the widths of the liquid flow path mainstream grooves 61a to 61f may gradually narrow from the liquid flow path mainstream grooves 61a, 61f closest to the steam flow path section 50 (steam passage 51) toward the liquid flow path mainstream grooves 61c, 61d located on the inner side in the width direction of each liquid flow path section 60.

For example, in the second modified example shown in Figures 13 and 14, of the multiple liquid flow path mainstream grooves 61a-61f, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f closest to the steam flow path section 50 (steam passage 51) are the widest. Furthermore, the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d located on the innermost side are the narrowest. The widths w3b and w3e of the other liquid flow path mainstream grooves 61b and 61e are between the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f and the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d. In other words, the following relationships hold: w3a, w3f > w3b, w3e > w3c, w3d.

In Figures 13 and 14, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f located on the outer side of each liquid flow path section 60 in the width direction are equal to each other, and the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d located on the inner side of each liquid flow path section 60 in the width direction are equal to each other. Furthermore, the widths w3b and w3e of the liquid flow path mainstream grooves 61b and 61e located between these are equal to each other. That is, the relationship w3a = w3f > w3b = w3e > w3c = w3d holds. However, this is not limiting, and the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f may be different from each other. Furthermore, the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d may be different from each other. Furthermore, the widths w3b and w3e of the liquid flow path mainstream grooves 61b and 61e may be different from each other.

The widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f are preferably 1.1 to 1.6 times the widths w3b and w3e of the adjacent liquid flow path mainstream grooves 61b and 61e located on the inner side in the width direction. Furthermore, the widths w3b and w3e of the liquid flow path mainstream grooves 61b and 61e are preferably 1.1 to 1.6 times the widths w3c and w3d of the adjacent liquid flow path mainstream grooves 61c and 61d located on the inner side in the width direction. The widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f may be, for example, 5.5 μm to 320 μm. The widths w3b and w3e of the liquid flow path mainstream grooves 61b and 61e may be, for example, 3.5 μm to 290 μm. The widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d may be, for example, 2.2 μm to 260 μm.

In FIG. 13, the depths h1a, h1b, and h1c of the liquid flow path mainstream grooves 61a-61f do not have to be uniform across all of the liquid flow path mainstream grooves 61a-61f. Specifically, the depth h1a of the liquid flow path mainstream grooves 61a, 61f located on the outer side of each liquid flow path section 60 in the width direction may be deeper than the depth h1b of the liquid flow path mainstream grooves 61b, 61e located on the inner side in the width direction. Furthermore, the depth h1b of the liquid flow path mainstream grooves 61b, 61e may be deeper than the depth h1c of the liquid flow path mainstream grooves 61c, 61d located on the inner side in the width direction (h1a > h1b > h1c). In this case, the depths h1a of the liquid flow path mainstream grooves 61a, 61f are equal to each other, and the depths h1b of the liquid flow path mainstream grooves 61b, 61e are equal to each other. Furthermore, the depths h1c of the liquid flow path mainstream grooves 61c, 61d are equal to each other. The depth h1a of the liquid flow path mainstream grooves 61a, 61f may be, for example, 3.5 μm or more and 240 μm or less. The depth h1b of the liquid flow path mainstream grooves 61b, 61e may be, for example, 3.3 μm or more and 200 μm or less. The depth h1c of the liquid flow path mainstream grooves 61c, 61d may be, for example, 3 μm or more and 150 μm or less. However, this is not limited to this, and the depths h1a of the liquid flow path mainstream grooves 61a, 61f may be different from each other, and the depths h1b of the liquid flow path mainstream grooves 61b, 61e may be different from each other. Furthermore, the depths h1c of the liquid flow path mainstream grooves 61c, 61d may be different from each other.

As described above, according to the second modified example, the widths of the liquid flow path mainstream grooves 61a-61f gradually narrow from the liquid flow path mainstream grooves 61a, 61f closest to the steam flow path section 50 toward the liquid flow path mainstream grooves 61c, 61d located on the inner side in the width direction of each liquid flow path section 60. This allows the condensed working fluid 2b from the steam flow path section 50 to be stored in the wider liquid flow path mainstream grooves 61a, 61f, even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61f located on the outer side in the width direction of each liquid flow path section 60 to the liquid flow path mainstream grooves 61c, 61d located on the inner side in the width direction is stagnant. This allows the working fluid 2b to be smoothly condensed from the steam flow path section 50 toward the liquid flow path section 60.

(Third Modification)
In the above-described embodiment, an example has been described in which the widths w3a, w3f of the liquid flow path mainstream grooves 61a, 61f located on the outer side in the width direction of each liquid flow path section 60 are equal to each other, and the widths w3b to w3e of the liquid flow path mainstream grooves 61b to 61e located on the inner side in the width direction of each liquid flow path section 60 are equal to each other. However, this is not limited to this, and the widths of the liquid flow path mainstream grooves 61a, 61f closest to the steam flow path section 50 (steam passage 51) and the widths of the liquid flow path mainstream grooves 61b, 61c second closest to the steam flow path section 50 (steam passage 51) may be equal to each other.

For example, in the third modified example shown in Figures 15 and 16, of the multiple liquid flow path mainstream grooves 61a-61f, the widths w3a and w3f of the liquid flow path mainstream grooves 61a and 61f closest to the steam flow path section 50 (steam passage 51) and the widths w3b and w3e of the liquid flow path mainstream grooves 61b and 61e second closest to the steam flow path section 50 (steam passage 51) are the widest. Furthermore, the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d located furthest inward in the width direction are the narrowest. In other words, the relationship w3a, w3b, w3e, w3f > w3c, w3d holds.

In Figures 15 and 16, the widths w3a, w3b, w3e, and w3f of the liquid flow path mainstream grooves 61a, 61b, 61e, and 61f are equal to each other, and the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d are equal to each other. In other words, the relationship w3a = w3b = w3e = w3f > w3c = w3d holds. However, this is not limiting, and the widths w3a, w3b, w3e, and w3f of the liquid flow path mainstream grooves 61a, 61b, 61e, and 61f may be different from each other. Furthermore, the widths w3c and w3d of the liquid flow path mainstream grooves 61c and 61d may be different from each other. In this modified example, the widths w3a, w3b, w3e, and w3f of two pairs (four grooves) of the liquid flow path mainstream grooves 61a, 61b, 61e, and 61f closest to the vapor flow path section 50 (vapor passage 51) are the same and are the widest. However, this is not limiting. Three or more pairs (six grooves) of the liquid flow path mainstream grooves closest to the vapor flow path section 50 (vapor passage 51) may have the same and are the widest. For example, if eight liquid flow path mainstream grooves are present, the widths of three pairs (six grooves) of the liquid flow path mainstream grooves closest to the vapor flow path section 50 (vapor passage 51) may have the same and are the widest.

As described above, according to the third modified example, two pairs (four) of wide liquid flow path mainstream grooves 61a, 61b, 61e, and 61f are provided, which provides a particularly large area for storing working fluid 2b. This allows for a larger amount of condensed working fluid 2b from the vapor flow path section 50 to be stored within the wide liquid flow path mainstream grooves 61a, 61b, 61e, and 61f, even when the flow of working fluid 2b from the liquid flow path mainstream grooves 61a, 61b, 61e, and 61f located on the outer width sides of each liquid flow path section 60 to the liquid flow path mainstream grooves 61c and 61d located on the inner width sides, to be stagnated.

(Fourth Modification)
In the above-described embodiment, an example has been described in which the protrusions 64 are arranged in a staggered pattern. However, this is not limited thereto, and the protrusions 64 may be arranged in a lattice pattern as shown in FIG. 17 . Specifically, when a point located at the center of each protrusion 64 in the X and Y directions is defined as a center point Pc, the center points Pc of the plurality of protrusions 64 are arranged in a lattice pattern. That is, the center points Pc of the plurality of protrusions 64 are arranged parallel to each other in the X and Y directions. In this case, even when the flow of the working fluid 2b from the liquid flow path main grooves 61a, 61f located on the outer sides of each liquid flow path section 60 toward the liquid flow path main grooves 61c, 61d located on the inner sides in the width direction is stagnated, a larger amount of the condensed working fluid 2b from the vapor flow path section 50 can be stored in the wide liquid flow path communication groove 65.

Second Embodiment
Next, a second embodiment will be described with reference to Figures 18 to 26. Figures 18 to 26 are diagrams showing the second embodiment. In Figures 18 to 26, the same parts as those shown in Figures 1 to 17 are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

As shown in FIG. 18 , the wick sheet 30 according to this embodiment has a first body surface 31a, a second body surface 31b, a vapor flow path portion 50, and a liquid flow path portion 60. The liquid flow path portion 60 is provided on the second body surface 31b of the wick sheet 30. The working fluid 2b mainly flows through the liquid flow path portion 60. This liquid flow path portion 60 constitutes part of the sealed space 3 described above 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 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 body surface 31b of each land portion 33.

As shown in Figure 19, the liquid flow path section 60 has a plurality of liquid flow path mainstream grooves 61 arranged parallel to one another and through which the hydraulic fluid 2b passes, and a plurality of liquid flow path communication grooves 65 that communicate with the liquid flow path mainstream grooves 61. In the example shown in Figure 19, each land section 33 includes six liquid flow path mainstream grooves 61, but this is not limited to this. The number of liquid flow path mainstream grooves 61 included in each land section 33 is arbitrary and may be, for example, between three and 20.

As shown in Figure 19, each liquid flow path mainstream groove 61 is formed to extend along the longitudinal direction (X direction) of the land portion 33. The multiple liquid flow path mainstream grooves 61 are arranged parallel to one another. Note that if the land portion 33 is curved in plan view, each liquid flow path mainstream groove 61 may extend in a curved manner along the curvature direction of the land portion 33. In other words, each liquid flow path mainstream groove 61 does not necessarily have to be formed linearly, and does not necessarily have to extend parallel to the X direction.

The liquid flow path mainstream grooves 61 have a smaller flow path cross-sectional area than the steam passages 51 of the steam flow path section 50, so that the working fluid 2b flows primarily by capillary action. The liquid flow path mainstream grooves 61 are 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 are arranged at intervals from each other in the width direction (Y direction).

The liquid flow path mainstream grooves 61 are formed by etching from the second main body surface 31b of the wick sheet 30 during the etching process for producing the wick sheet 30. As shown in FIG. 18, the liquid flow path mainstream grooves 61 have curved wall surfaces 62. 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. In the cross section shown in FIG. 18, the radius of curvature of each wall surface 62 is preferably smaller than the radius of curvature of the second wall surface 54a of the steam passage 51.

In Figure 19, the width w3 of all liquid flow path mainstream grooves 61 is uniform. In this case, the cross-sectional shapes (depth, width, etc.) of the multiple liquid flow path mainstream grooves 61 may be symmetrical about the center of the width direction (Y direction) of the land portion 33. However, this is not limited to this, and the widths w3 of the liquid flow path mainstream grooves 61 may be different from each other. Note that the width w3 of the liquid flow path mainstream groove 61 refers to the length in the direction perpendicular to the longitudinal direction of the land portion 33, which in this case is the dimension in the Y direction. The width w3 of the liquid flow path mainstream groove 61 refers to the dimension at the second main body surface 31b. The width w3 of the liquid flow path mainstream groove 61 may be, for example, 2.2 μm or more and 320 μm or less.

Furthermore, as shown in FIG. 18, the depth h1 of the liquid flow path mainstream grooves 61 is uniform among all of the liquid flow path mainstream grooves 61. However, this is not limited to this, and the depth h1 of the liquid flow path mainstream grooves 61 may differ among the liquid flow path mainstream grooves 61. The depth h1 of the liquid flow path mainstream grooves 61 may be, for example, 3 μm or more and 240 μm or less. Note that the depth h1 of the liquid flow path mainstream groove 61 is the distance measured from the second main body surface 31b in a direction perpendicular to the second main body surface 31b, which in this case is the dimension in the Z direction. Furthermore, the depth h1 refers to the depth at the deepest point of the liquid flow path mainstream groove 61.

As shown in FIG. 19 , 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 steam flow path section 50 (steam passage 51) to the liquid flow path mainstream groove 61 closest to the steam flow path section 50. In other words, the liquid flow path communication groove 65 extends from the end side of the land portion 33 in the Y direction to the liquid flow path mainstream groove 61 adjacent to that end. In this way, the steam passage 51 of the steam flow path section 50 and the liquid flow path mainstream groove 61 are connected to each other.

The liquid flow path communication grooves 65 have a smaller flow path cross-sectional area than the steam passages 51 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 longitudinal direction (X direction) of the land section 33.

Like the liquid flow path main groove 61, the liquid flow path communication groove 65 is also formed by etching and has a wall surface (not shown) formed in a curved shape similar to the liquid flow path main groove 61. As shown in FIG. 19, the width w4 (dimension in the X direction) of the liquid flow path communication groove 65 may be 5 μm or more and 300 μm or less. The depth of the liquid flow path communication groove 65 may be 3 μm or more and 240 μm or less.

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. In this case, at the liquid flow path intersection 66, 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. 19 ). This prevents the liquid flow path communication groove 65 on the other side (e.g., the lower side in FIG. 19 ) from communicating with the liquid flow path mainstream groove 61 at the liquid flow path intersection 66. This prevents the wall surface 62 of the liquid flow path mainstream groove 61 from being cut out on both sides in the Y direction at the liquid flow path intersection 66, leaving one side of the wall surface 62 intact. As a result, capillary action can be imparted to the working fluid 2b in the liquid flow path main groove 61, even at the liquid flow path intersection 66, and the driving force of the working fluid 2b toward the evaporation region SR can be prevented from decreasing at the liquid flow path intersection 66.

As shown in Figure 19, convex rows 63 are provided between adjacent liquid flow path main grooves 61 of the liquid flow path section 60. Note that in the example shown in Figure 19, each land section 33 includes seven convex rows 63, but this is not limited to this. The number of convex rows 63 included in each land section 33 is arbitrary, and may be, for example, between three and twenty rows.

As shown in FIG. 19, each protrusion row 63 is formed to extend along the longitudinal direction (X direction) of the land portion 33. The multiple protrusion rows 63 are arranged parallel to one another. Note that if the land portion 33 is curved in plan view, each protrusion row 63 may extend in a curved manner along the curvature direction of the land portion 33. In other words, each protrusion row 63 does not necessarily have to be formed in a straight line, and does not necessarily have to extend parallel to the X direction. Each protrusion row 63 is arranged at intervals from one another in the width direction (Y direction).

Each protrusion row 63 includes multiple protrusions 64a-64g (liquid flow path protrusions) arranged in the X direction. Protrusions 64a-64g are arranged in the following order from the positive side of the Y direction to the negative side of the Y direction: protrusion 64a, protrusion 64b, protrusion 64c, protrusion 64d, protrusion 64e, protrusion 64f, and protrusion 64g. Of these, protrusions 64a and 64g are closest to the steam flow path section 50 (steam passage 51) and are located on the outermost side of the liquid flow path section 60 in the Y direction. Protrusion 64d is located farthest from the steam flow path section 50 (steam passage 51) and is located on the innermost side of the liquid flow path section 60 in the Y direction.

The protrusions 64a to 64g are provided within the liquid flow path section 60 and protrude from the liquid flow path mainstream grooves 61 and the liquid flow path connecting grooves 65 to abut against the upper sheet 20. Each of the protrusions 64a to 64g is formed rectangular in plan view, with its longitudinal direction in the X direction. A liquid flow path mainstream groove 61 is disposed between adjacent protrusions 64a to 64g in the Y direction. A liquid flow path connecting groove 65 is disposed between adjacent protrusions 64a to 64g in the X direction. The liquid flow path connecting groove 65 is formed to extend in the Y direction, connecting 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 protrusions 64a to 64g are portions that are not etched during the etching process used to fabricate the wick sheet 30, and the material of the wick sheet 30 remains. In this embodiment, as shown in Figure 19, the planar shape of the protrusions 64a to 64g (the shape at the position of the second main body surface 31b of the wick sheet 30) is rectangular.

As shown in FIG. 19, the widths of the protrusions 64a-64g are not uniform among all of the protrusions 64a-64g. Specifically, the width of the protrusions 64a, 64g (hereinafter also referred to as protrusions 64a, 64g) in the protrusion row 63 closest to the steam flow path section 50 (steam passage 51) is narrower than the widths of the protrusions 64b-64f (hereinafter also referred to as protrusions 64b-64f) in the other protrusion rows 63. In other words, when the widths of the protrusions 64a-64g are w5a-w5g, respectively, the widths w5a, w5g of the protrusions 64a, 64g are narrower than the widths w5b-w5f of the protrusions 64b-64f (w5a, w5g < w5b-w5f). Note that in this embodiment, the widths of multiple protrusions included in the same protrusion row 63 are uniform.

In FIG. 19, the widths w5a and w5g of the convex portions 64a and 64g of the convex portion row 63 located on the outer side of each liquid flow path section 60 in the width direction are equal to each other, and the widths w5b to w5f of the convex portions 64b to 64f of the convex portion row 63 located on the inner side of each liquid flow path section 60 in the width direction are equal to each other. That is, the relationship w5a = w5g < w5b = w5c = w5d = w5e = w5f holds. However, this is not limited to this, and the widths w5a and w5g of the convex portions 64a and 64g may be different from each other. The widths w5b to w5f of the convex portions 64b to 64f may also be different from each other. However, it is preferable that the wider of the widths w5a and w5g of the convex portions 64a and 64g is narrower than the narrowest of the widths w5b to w5f of the convex portions 64b to 64f.

The widths w5a and w5g of the convex portions 64a and 64g are preferably 0.3 to 0.95 times the widths w5b to w5f of the convex portions 64b to 64f. A ratio of 0.3 or more allows for stable production of the shapes of the convex portions 64a and 64g. On the other hand, a ratio of 0.95 or less allows for smooth evaporation and condensation of the working fluid 2b between the steam passage 51 and the liquid flow path mainstream groove 61. Furthermore, it is possible to facilitate the flow of working fluid 2b from the liquid flow path mainstream groove 61 located on the outer side of each liquid flow path section 60 in the width direction to the liquid flow path mainstream groove 61 located on the inner side of each liquid flow path section 60 in the width direction.

The widths w5a to w5g of the protrusions 64a to 64g refer to the length perpendicular to the longitudinal direction of the land portion 33, which in this case is the dimension in the Y direction. The widths w5a to w5g of the protrusions 64a to 64g refer to the dimension on the second main body surface 31b. The widths w5a and w5g of the protrusions 64a and 64g located on the outer side of each liquid flow path section 60 in the width direction may be, for example, 1.5 μm or more and 475 μm or less. The widths w5b to w5f of the protrusions 64b to 64f located on the inner side of each liquid flow path section 60 in the width direction may be, for example, 5 μm or more and 500 μm or less.

The arrangement pitch of the convex portions 64a-64g in the width direction (Y direction) of the convex portions 64a-64g is non-uniform among the convex portions 64a-64g. That is, the arrangement pitch P1 between the convex portion 64a (64g) closest to the steam flow path portion 50 (steam passage 51) and the convex portion 64b (64f) adjacent to that convex portion 64a in the Y direction is narrower than the arrangement pitch P2 between the other convex portions 64b-64f (P1 < P2). Here, the arrangement pitch of the convex portions 64a-64g refers to the distance measured in the Y direction between the center of the convex portion 64a-64g in the Y direction and the center of the adjacent convex portion 64a-64g in the Y direction. The arrangement pitch P1 between the convex portion 64a (64g) and the convex portion 64b (64f) may be, for example, 30 μm or more and 800 μm or less. The arrangement pitch P2 between the other protrusions 64b-64f may be, for example, 35 μm or more and 1000 μm or less. However, this is not limited to this, and the arrangement pitch in the width direction of the protrusions 64a-64g may all be uniform between the protrusions 64a-64g.

In this embodiment, the protrusions 64a to 64g are arranged in a staggered (alternate) pattern. More specifically, the protrusions 64a to 64g of the protrusion rows 63 that are adjacent to each other in the Y direction are arranged with a shift in the X direction. This shift may be half the arrangement pitch of the protrusions 64a to 64g in the X direction. Note that the arrangement of the protrusions 64a to 64g is not limited to a staggered pattern, and they may also be arranged in parallel. In this case, the protrusions 64a to 64g of the protrusion rows 63 that are adjacent to each other in the Y direction are also aligned in the X direction (see Figure 26).

The length L1 (dimension in the X direction) of the protrusions 64a-64g may be uniform among the protrusions 64a-64g. Furthermore, the length L1 of the protrusions 64a-64g is longer than the width w4 of the liquid flow path connecting groove 65 (L1 > w4). Note that the length L1 of the protrusions 64a-64g refers to the maximum dimension in the X direction on the second main body surface 31b.

The vapor chamber 1 and wick sheet 30 of this embodiment can be fabricated in the same manner as in the first embodiment (see Figure 10).

Next, we will describe the operation of this embodiment configured as described above.

In the evaporation region SR, working vapor 2a generated from working fluid 2b moves from the liquid flow path section 60 toward the vapor passage 51. At this time, working vapor 2a passes from the liquid flow path mainstream groove 61 through the liquid flow path connecting groove 65 adjacent to the convex portions 64a, 64g on the widthwise outer sides of each liquid flow path section 60, and flows out into the vapor passage 51. Meanwhile, in the condensation region CR, working fluid 2b generated from working vapor 2a moves from the vapor passage 51 toward the liquid flow path section 60. At this time, working fluid 2b passes through the liquid flow path connecting groove 65 adjacent to the convex portions 64a, 64g on the widthwise outer sides of each liquid flow path section 60, and enters the liquid flow path mainstream groove 61.

In this embodiment, of the multiple protrusions 64a-64g, the widths w5a and w5g of the protrusions 64a and 64g in the protrusion row 63 closest to the vapor passage 51 are narrower than the widths w5b-w5f of the protrusions 64b-64f in the other protrusion rows 63. As a result, the length (distance in the Y direction) of the liquid flow path connection groove 65 adjacent to the protrusions 64a and 64g is shortened, reducing the flow path resistance of the liquid flow path connection groove 65. This reduces flow path resistance on the outer side of the liquid flow path section 60 in the width direction (Y direction), allowing the working vapor 2a or working liquid 2b to flow smoothly between the vapor passage 51 and the liquid flow path section 60. As a result, the condensation of the working vapor 2a or the evaporation of the working liquid 2b can be smoothly performed between the vapor passage 51 and the liquid flow path section 60, improving the cooling capacity of the vapor chamber 1.

Furthermore, according to this embodiment, the arrangement pitch P1 between the convex portions 64a, 64g of the convex portion row 63 closest to the steam flow path section 50 (steam passage 51) and the convex portions 64b, 64f of the convex portion row 63 adjacent to the convex portions 64a, 64g of the convex portion row 63 is narrower than the arrangement pitch P2 between the convex portions 64b-64f of the other convex portion rows 63. This makes it easier for capillary force to occur in the working fluid 2b in the liquid flow path mainstream groove 61 close to the steam flow path section 50 (steam passage 51).

Furthermore, according to this embodiment, the widths w3 of the multiple liquid flow path main grooves 61 are uniform. This allows the capillary force acting on the working fluid 2b to be uniform across the width of the liquid flow path section 60.

(Modification)
Next, various modified examples of this embodiment will be described with reference to Figures 20 to 26. Figures 20 to 26 are views showing modified wick sheets 30. In Figures 20 to 26, the same parts as those shown in Figures 1 to 19 are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

(First Modification)
In the above-described embodiment, an example has been described in which the width w3 of the plurality of liquid flow path mainstream grooves 61 is uniform between the respective liquid flow path mainstream grooves 61. However, this is not limitative, and the width of the liquid flow path mainstream grooves 61 may be non-uniform between the respective liquid flow path mainstream grooves 61.

For example, as shown in a first modified example in FIGS. 20 and 21 , the width w3a of the liquid flow path mainstream groove 61a closest to the vapor flow path section 50 (vapor passage 51) may be wider than the width w3b of the other liquid flow path mainstream grooves 61b. In this case, the widths w3a of the two liquid flow path mainstream grooves 61a closest to the vapor flow path section 50 (vapor passage 51) are equal to each other, and the widths w3b of the other four liquid flow path mainstream grooves 61b are equal to each other. The width w3a of the liquid flow path mainstream groove 61a is preferably 1.1 to 1.6 times the width w3b of the liquid flow path mainstream groove 61b. A ratio of 1.1 or more enhances the capillary force in the central liquid flow path mainstream groove 61b, facilitating the transport of the working fluid 2b toward the evaporation region SR. A ratio of 1.6 or less suppresses a decrease in the transport rate of the working fluid 2b in the liquid flow path mainstream grooves 61b located on the inner side of each liquid flow path section 60 in the width direction.

Also, as shown in FIG. 20, the depth h1a of the liquid flow path mainstream groove 61a closest to the vapor flow path section 50 (vapor passage 51) may be deeper than the depth h1b of the other liquid flow path mainstream grooves 61b.

In this modified example, the widths w5a and w5g of the protrusions 64a and 64g in the protrusion row 63 closest to the vapor passage 51 are narrower than the widths w5b and w5f of the protrusions 64b and 64f in the other protrusion rows 63. This shortens the length (distance in the Y direction) of the liquid flow path connecting groove 65 adjacent to the protrusions 64a and 64g, lowering the flow path resistance of the liquid flow path connecting groove 65. This reduces flow path resistance on the outer side of the liquid flow path section 60 in the width direction (Y direction), allowing the working vapor 2a or working liquid 2b to flow smoothly between the vapor passage 51 and the liquid flow path section 60. As a result, the condensation of the working vapor 2a or the evaporation of the working liquid 2b can be smoothly performed between the vapor passage 51 and the liquid flow path section 60, improving the cooling capacity of the vapor chamber 1.

As described above, according to the first modification, the width w3a of the liquid flow path mainstream groove 61a located on the outer side of each liquid flow path section 60 in the width direction is wider than the width w3b of the other liquid flow path mainstream grooves 61b. This allows the condensed working fluid 2b from the vapor flow path section 50 to be stored within the wider liquid flow path mainstream groove 61a, even if the flow of working fluid 2b from the liquid flow path mainstream groove 61a located on the outer side of each liquid flow path section 60 to the liquid flow path mainstream groove 61b located on the inner side in the width direction is impeded. This allows the working fluid 2b to be smoothly condensed from the vapor flow path section 50 toward the liquid flow path section 60. As a result, the pressure difference between the vicinity of the evaporation region SR and the condensation region CR is maintained, preventing a decrease in the cooling capacity of the vapor chamber 1.

(Second Modification)
In the above-described embodiment, an example has been described in which the widths w5a, w5g of the convex portions 64a, 64g of the convex portion row 63 located on the outer side in the width direction of each liquid flow path section 60 are equal to each other, and the widths w5b to w5f of the convex portions 64b to 64f located on the inner side in the width direction of each liquid flow path section 60 are equal to each other. However, this is not limiting, and the widths of the convex portions 64a to 64g may gradually increase from the convex portions 64a, 64g closest to the steam flow path section 50 (steam passage 51) toward the convex portion 64d located on the inner side in the width direction.

For example, in the second modified example shown in Figures 22 and 23, of the multiple protrusions 64a to 64g, the widths w5a and w5g of the protrusions 64a and 64g in the protrusion row 63 closest to the steam flow path section 50 (steam passage 51) are the narrowest. Furthermore, the width w5d of the protrusion 64d in the protrusion row 63 located furthest inward in the width direction is the widest. The widths w5b and w5f of the protrusions 64b and 64f are wider than the widths w5a and w5g of the protrusions 64a and 64g, and the widths w5c and w5e of the protrusions 64c and 64e are wider than the widths w5b and w5f of the protrusions 64b and 64f. In other words, the relationships w5a, w5g < w5b, w5f < w5c, and w5e < w5d hold true.

In Figures 22 and 23, the widths w5a and w5g of the convex portions 64a and 64g located on the outer sides of each liquid flow path section 60 in the width direction are equal to each other, and the widths w5b and w5f of the convex portions 64b and 64f are equal to each other. Furthermore, the widths w5c and w5e of the convex portions 64c and 64e are equal to each other. That is, the relationship w5a = w5g < w5b = w5f < w5c = w5e < w5d holds. However, this is not limiting, and the widths w5a and w5g of the convex portions 64a and 64g may be different from each other. Furthermore, the widths w5b and w5f of the convex portions 64b and 64f may be different from each other. Furthermore, the widths w5c and w5e of the convex portions 64c and 64e may be different from each other.

The widths w5b to w5f of each of the convex portions 64b to 64f are preferably 1.1 to 1.5 times the widths w5a to w5c and w5e to w5g of the convex portions 64a to 64c and 64e to 64g adjacent to the outer side in the width direction of the liquid flow path portion 60. In other words, the widths w5b and w5f of the convex portions 64b and 64f are preferably 1.1 to 1.5 times the widths w5a and w5g of the convex portions 64a and 64g. Furthermore, the widths w5c and w5e of the convex portions 64c and 64e are preferably 1.1 to 1.5 times the widths w5b and w5f of the convex portions 64b and 64f. Furthermore, the width w5d of the convex portion 64d is preferably 1.1 to 1.5 times the widths w5c and w5e of the convex portions 64c and 64e.

Specifically, the widths w5a and w5g of the protrusions 64a and 64g may be, for example, 1.5 μm or more and 430 μm or less. The widths w5b and w5f of the protrusions 64b and 64f may be, for example, 1.5 μm or more and 450 μm or less. The widths w5c and w5e of the protrusions 64c and 64e may be, for example, 1.5 μm or more and 475 μm or less. The width w5d of the protrusion 64d may be, for example, 5 μm or more and 500 μm or less.

In Figures 22 and 23, the width w3 of all liquid flow path mainstream grooves 61 is uniform. However, this is not limited to this, and the width of each liquid flow path mainstream groove 61 may be uneven between each liquid flow path mainstream groove 61.

As described above, according to the second modified example, the widths of the convex portions 64a-64g gradually increase from the convex portions 64a and 64g of the convex portion row 63 closest to the vapor flow path section 50 (vapor passage 51) toward the convex portion 64d of the convex portion row 63 located most inward in the width direction. This reduces the flow resistance of the liquid flow path connecting grooves 65 on the outer sides of the liquid flow path section 60 in the width direction (Y direction) compared to the flow resistance of the liquid flow path connecting grooves 65 located on the inner sides in the width direction. This allows the working vapor 2a or working liquid 2b to flow smoothly in and out between the vapor passage 51 and the liquid flow path section 60. As a result, the working vapor 2a can condense or the working liquid 2b can evaporate smoothly between the vapor passage 51 and the liquid flow path section 60, thereby improving the cooling capacity of the vapor chamber 1.

Furthermore, if the working fluid 2b is water, the water freezes and expands when the temperature of the vapor chamber 1 drops below freezing. Because water expands under high pressure, the housing H may expand if pressure is applied to expand the vapor chamber 1 in the thickness direction. At the same time, the protrusions 64a-64g may peel off, stretch, or tear from the land portion 33. According to this modification, the width of the multiple protrusions 64a-64g gradually increases from the protrusions 64a, 64g of the protrusion row 63 closest to the vapor flow path 50 toward the protrusion 64d of the protrusion row 63 located on the inner side of the liquid flow path 60 in the width direction. This allows the pressure generated by the expansion of water within the inner liquid flow path 60 (for example, around the protrusion 64d) to escape relatively easily toward the vapor path 51, thereby minimizing deformation of the protrusions 64a-64g during freezing and expansion.

(Third Modification)
In the above-described embodiment, an example has been described in which the widths w5a, w5g of the convex portions 64a, 64g of the convex portion row 63 located on the outer side in the width direction of each liquid flow path section 60 are equal to each other, and the widths w5b to w5f of the convex portions 64b to 64f of the convex portion row 63 located on the inner side in the width direction are equal to each other. However, this is not limited to this, and the widths of the convex portions 64a, 64g of the convex portion row 63 closest to the steam flow path section 50 (steam passage 51) and the widths of the convex portions 64b, 64f of the convex portion row 63 second closest to the steam flow path section 50 (steam passage 51) may be equal to each other.

For example, in the third modified example shown in Figures 24 and 25, of the multiple protrusions 64a to 64g, the widths w5a and w5g of the protrusions 64a and 64g in the protrusion row 63 closest to the steam flow path section 50 (steam passage 51) are narrow, and the widths w5b and w5f of the protrusions 64b and 64f in the protrusion row 63 second closest to the steam flow path section 50 (steam passage 51) are narrow. Furthermore, the widths w5c to w5e of the protrusions 64c to 64e in the protrusion row 63 located on the inner side in the width direction are wide. In other words, the relationship w5a, w5b, w5f, w5g > w5c to w5e holds.

In Figures 24 and 25, the widths w5a, w5b, w5f, and w5g of the protrusions 64a, 64b, 64f, and 64g are equal to each other, and the widths w5c to w5e of the protrusions 64c to 64e are equal to each other. In other words, the relationship w5a = w5b = w5f = w5g < w5c = w5d = w5e holds. However, this is not limiting, and the widths w5a, w5b, w5f, and w5g of the protrusions 64a, 64b, 64f, and 64g may be different from each other. Furthermore, the widths w5c to w5e of the protrusions 64c to 64e may be different from each other.

As described above, according to the third modified example, two pairs (four) of narrow protrusions 64a, 64b, 64f, and 64g are provided. This reduces flow path resistance, particularly on the outer sides of the liquid flow path section 60 in the width direction (Y direction), allowing the working vapor 2a or working liquid 2b to flow smoothly in and out between the vapor passage 51 and the liquid flow path section 60. As a result, condensation of the working vapor 2a or evaporation of the working liquid 2b can be carried out smoothly between the vapor passage 51 and the liquid flow path section 60, thereby improving the cooling capacity of the vapor chamber 1.

(Fourth Modification)
In the above-described embodiment, the protrusions 64a to 64g are arranged in a staggered pattern. However, this is not limiting. As shown in FIG. 26 , the protrusions 64a to 64g may be arranged in a lattice pattern. Specifically, when the center point Pc of each of the protrusions 64a to 64g in the X and Y directions is defined as a center point Pc, the center points Pc of the plurality of protrusions 64a to 64g are arranged in a lattice pattern. That is, the center points Pc of the plurality of protrusions 64a to 64g are arranged parallel to each other in the X and Y directions. In this case, the flow resistance of the liquid flow path communication groove 65 on the outer side of the width direction (Y direction) of the liquid flow path section 60 is reduced, allowing the working steam 2a or working liquid 2b to flow smoothly in and out between the vapor passage 51 and the liquid flow path section 60.

The present disclosure is not limited to the above-described embodiments and modifications, and in the implementation stage, the components can be modified to achieve specific implementations 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 embodiments and modifications. Some components may be omitted from all of the components shown in each embodiment and modification.

Claims (1)

A vapor chamber containing a working fluid,
The first sheet,
A second seat;
a wick sheet interposed between the first sheet and the second sheet,
The wick sheet is
a first body surface;
a second body surface located opposite the first body surface;
a vapor flow path portion extending from the first body surface to the second body surface and through which the vapor of the working fluid passes; and a liquid flow path portion provided on the second body surface and communicating with the vapor flow path portion and through which the liquid working fluid passes,
the liquid flow path portion has a plurality of liquid flow path mainstream grooves through which the liquid working fluid passes and which are arranged parallel to each other;
A vapor chamber, wherein the width of the liquid flow path mainstream groove closest to the vapor flow path portion among the plurality of liquid flow path mainstream grooves is wider than the widths of the other liquid flow path mainstream grooves.