Wick sheet for vapor chamber, vapor chamber and electronic device

Abstract

To provide a wick sheet for a vapor chamber capable of suppressing the deterioration of performance, a vapor chamber and an electronic apparatus.SOLUTION: A wick sheet 30 for a vapor chamber is interposed between a first sheet 10 and a second sheet 20 of a vapor chamber sealing a working fluid. The wick sheet 30 for the vapor chamber includes a sheet body 31 that has a first body surface 31a and a second body surface 31b, a penetration space 50 penetrating the sheet body 31, a first groove assembly 60 provided on the second body surface 31b and communicated with the penetration space 50, and a second groove assembly 70 provided on the first body surface 31a and communicated with the penetration space 50. A channel cross-sectional area of a second main flow groove of the second groove assembly 70 is larger than a channel cross-sectional area of a first main flow groove of the first groove assembly 60.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wick sheet for a vapor chamber, a vapor chamber, and an electronic device. [Background technology]

[0002] Electronic devices such as mobile terminals use heat-generating electronic devices. Examples of such electronic devices include central processing units (CPUs), light-emitting diodes (LEDs), and power semiconductors. Examples of mobile terminals include handheld terminals and tablet terminals.

[0003] Such electronic devices are cooled by heat dissipation devices such as heat pipes (see, for example, Patent Document 1). In recent years, there has been a demand for thinner heat dissipation devices in order to make electronic devices thinner. Vapor chambers, which can be made thinner than heat pipes, have been developed as heat dissipation devices. Vapor chambers cool electronic devices by absorbing and diffusing the heat of the electronic device using an enclosed working fluid.

[0004] More specifically, the working fluid in the vapor chamber receives heat from the electronic device at a portion (evaporator) close to the electronic device. This causes the working fluid to evaporate and transform into working vapor. The working vapor diffuses away from the evaporator within a vapor channel formed in the vapor chamber and cools. The working vapor then condenses and transforms into working fluid. The vapor chamber is provided with a liquid channel having a capillary structure (also called a wick). This allows the working fluid to enter the liquid channel from the vapor channel. The working fluid then flows through the liquid channel and is transported toward the evaporator. The working fluid transported to the evaporator then receives heat again in the evaporator and evaporates. This causes the working fluid to circulate within the vapor chamber while repeatedly changing phases, i.e., evaporating and condensing. In this way, heat from the electronic device is diffused. As a result, the heat dissipation efficiency of the vapor chamber is improved. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-82698 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a wick sheet for a vapor chamber, a vapor chamber, and an electronic device that can suppress performance degradation. [Means for solving the problem]

[0007] As a first solution, the present invention provides: A wick sheet for a vapor chamber interposed between a first sheet and a second sheet of the vapor chamber in which a working fluid is sealed, a seat body having a first body surface and a second body surface provided on the opposite side of the first body surface; a through space that penetrates the seat body; a first groove assembly provided on the second body surface and communicating with the through space; a second groove assembly provided on the first body surface and communicating with the through space; the first groove assembly includes a plurality of first main grooves extending in a first direction, the second groove assembly includes a plurality of second main grooves extending in the first direction, a wick sheet for a vapor chamber, wherein a flow path cross-sectional area of ​​the second mainstream groove is larger than a flow path cross-sectional area of ​​the first mainstream groove; to provide.

[0008] In the wick sheet for a vapor chamber according to the first solution described above, The width of the second main groove is greater than the width of the first main groove. This may be done.

[0009] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The depth of the second main groove is greater than the depth of the first main groove. This may be done.

[0010] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The seat body has a plurality of land portions that divide the through space into a plurality of passages, the plurality of land portions are spaced apart from one another in a second direction perpendicular to the first direction, the width of the second main groove is smaller than the gap between a pair of adjacent land portions; This may be done.

[0011] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The seat body has a plurality of land portions that divide the through space into a plurality of passages, the first groove aggregate and the second groove aggregate are provided in at least one of the plurality of land portions, the number of the second main grooves provided in the land portion is smaller than the number of the first main grooves provided in the land portion; This may be done.

[0012] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The seat body has a plurality of land portions extending in the first direction and dividing the through-space into a plurality of passages, the second groove assembly is disposed on one side of the land portion in the first direction. This may be done.

[0013] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The seat body has a plurality of land portions that divide the through space into a plurality of passages, a pair of the land portions adjacent to each other in a second direction perpendicular to the first direction are provided with the second groove assemblies adjacent to each other in the second direction, a length in the first direction of the second main groove of the second groove aggregate provided in one of the land portions is longer than a length in the first direction of the second main groove of the second groove aggregate provided in the other of the land portions; This may be done.

[0014] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The seat body has a plurality of land portions that divide the through space into a plurality of passages, a plurality of the second groove aggregates are provided in at least one of the plurality of land portions; This may be done.

[0015] Furthermore, in the wick sheet for a vapor chamber according to the first solution, a communication portion provided in the seat body and communicating with the first groove assembly and the second groove assembly; This may be done.

[0016] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The communication portion includes a communication recess provided on a wall surface of the through-space and extending from the first groove assembly to the second groove assembly. This may be done.

[0017] Furthermore, in the wick sheet for a vapor chamber according to the first solution, the first groove assembly includes a first communication groove extending in a direction different from the first direction and communicating with the first main groove, the second groove assembly includes a second communication groove extending in a direction different from the first direction and communicating with the second main groove, The communication recess may extend to at least one of the first communication groove and the second communication groove.

[0018] Furthermore, in the wick sheet for a vapor chamber according to the first solution, The communication portion includes a through-hole that penetrates the seat body and extends from the first groove assembly to the second groove assembly. This may be done.

[0019] Furthermore, in the wick sheet for a vapor chamber according to the first solution, the first groove assembly includes a first communication groove extending in a direction different from the first direction and communicating with the first main groove, the first main groove includes a first intersection portion communicating with the first connecting groove, the second groove assembly includes a second communication groove extending in a direction different from the first direction and communicating with the first main groove, the second main groove includes a second intersection portion communicating with the second connecting groove, The through hole may extend to at least one of the first intersection and the second intersection.

[0020] As a second solution, the present invention provides: The first sheet and The second sheet, a vapor chamber including a wick sheet for a vapor chamber according to the first solution means interposed between the first sheet and the second sheet; to provide.

[0021] As a third solution, the present invention provides: Housing and an electronic device contained within the housing; an electronic device comprising: a vapor chamber according to the second solution described above in thermal contact with the electronic device; to provide.

[0022] In the electronic device according to the third solution described above, the second groove assembly is arranged in a region of the vapor chamber that is different from a region that overlaps with the electronic device in a plan view; This may be done.

[0023] In addition, in the vapor chamber according to the second solution, The working fluid has freeze-expansion properties. This may be done.

[0024] As a fourth solution, the present invention provides: Housing and an electronic device contained within the housing; An electronic device comprising: a vapor chamber according to the second solution described above, in thermal contact with the electronic device.

[0025] In the electronic device according to the fourth solution, The second groove assembly may be arranged in a region of the vapor chamber that overlaps with the electronic device in a plan view.

[0026] Furthermore, in the electronic device according to the fourth solution, the second groove assembly protrudes outward beyond the electronic device in the first direction; This may be done.

[0027] Furthermore, in the electronic device according to the fourth solution, The sheet body has a first overlapping land portion and a second overlapping land portion that divide the through space into a plurality of passages, the first overlapping land portion and the second overlapping land portion are spaced apart from each other in a second direction perpendicular to the first direction, the second groove assembly is provided in the first overlapping land portion and the second overlapping land portion, the second groove assembly provided in the first polymer land portion and the second groove assembly provided in the second polymer land portion are arranged in an area of ​​the vapor chamber that overlaps with the electronic device in a plan view, the second groove assembly provided in the first polymer land portion is located closer to the center of the electronic device in a second direction perpendicular to the first direction in a plan view of the vapor chamber than the second groove assembly provided in the second polymer land portion, a length in the first direction of the second groove aggregate provided in the first overlapping land portion is longer than a length in the first direction of the second groove aggregate provided in the second overlapping land portion; This may be done.

[0028] Furthermore, in the electronic device according to the fourth solution, The sheet body has a polymerized land portion and a non-polymerized land portion that divide the through space into a plurality of passages, the overlapping land portion and the non-overlapping land portion are spaced apart from each other and adjacent to each other in a second direction perpendicular to the first direction, the second groove assembly is provided in the overlapping land portion and the non-overlapping land portion, the second groove assembly provided in the polymer land portion is arranged in a region overlapping with the electronic device in a plan view of the vapor chamber, the second groove assembly provided in the non-polymerized land portion is arranged in a region different from a region overlapping with the electronic device in a plan view of the vapor chamber. This may be done.

[0029] Furthermore, in the electronic device according to the fourth solution, a length in the first direction of the second groove aggregate provided in the overlapping land portion is longer than a length in the first direction of the second groove aggregate provided in the non-overlapping land portion; This may be done.

[0030] As a fifth solution, the present invention provides: The first sheet and The second sheet, a wick sheet for a vapor chamber according to the first solution means interposed between the first sheet and the second sheet; a vapor chamber, wherein the working fluid has freeze expansion properties; to provide.

[0031] As a sixth solution, the present invention provides: Housing and a plurality of electronic devices housed within the housing; a vapor chamber according to the fifth solution in thermal contact with a plurality of the electronic devices; the plurality of electronic devices are arranged in different regions in the first direction, a plurality of the second groove assemblies are provided on the first body surface, each corresponding to one of the electronic devices; an electronic device, wherein the second groove assembly is arranged in a region overlapping the corresponding electronic device in a plan view of the vapor chamber; to provide.

[0032] As a seventh solution, the present invention provides: A wick sheet for a vapor chamber interposed between a first sheet and a second sheet of the vapor chamber in which a working fluid is sealed, a seat body having a first body surface and a second body surface provided on the opposite side of the first body surface; a vapor flow path portion that penetrates from the first main body surface to the second main body surface of the sheet body and through which the gas of the working fluid passes; a liquid flow path portion provided on the second main body surface, communicating with the vapor flow path portion and through which the liquid of the working fluid passes; a liquid storage portion provided on the first main body surface and communicating with the vapor flow path portion to store the liquid of the working fluid; to provide.

[0033] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the liquid flow path portion has a plurality of liquid flow path mainstream grooves through which the liquid of the working fluid passes, a plurality of liquid storage protrusions protruding from the sheet body and contacting the first sheet are provided in the liquid storage section; a gap between a pair of adjacent liquid storage protrusions is larger than a width of the liquid flow path main groove; This may be done.

[0034] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the liquid flow path portion has a plurality of liquid flow path mainstream grooves extending in a first direction and through which the liquid of the working fluid passes, the liquid storage portion has a plurality of liquid storage main grooves extending in the first direction and provided between the liquid storage protrusions adjacent to each other in a second direction perpendicular to the first direction; This may be done.

[0035] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the seat body has a plurality of land portions that divide the steam flow path portion into a plurality of steam passages, a gap between a pair of adjacent liquid storage protrusions is smaller than a gap between a pair of adjacent land portions; This may be done.

[0036] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the seat body has a plurality of land portions that divide the steam flow path portion into a plurality of steam passages, the liquid storage portion is provided in each of the land portions; This may be done.

[0037] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the sheet body has a plurality of land portions extending in a first direction and dividing the steam flow path portion into a plurality of steam passages, the liquid storage portion is disposed on one side of the land portion in the first direction. This may be done.

[0038] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, a communication section provided in the sheet body and communicating with the liquid flow path section and the liquid storage section; This may be done.

[0039] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the communication section includes a communication recess provided in a wall surface of the vapor flow path section and extending from the liquid flow path section to the liquid storage section; This may be done.

[0040] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the liquid flow path section has a plurality of liquid flow path mainstream grooves extending in a first direction and through which the liquid of the working fluid passes, and liquid flow path communication grooves extending in a direction different from the first direction and communicating with the liquid flow path mainstream grooves, the liquid storage portion has a plurality of liquid storage main grooves extending in the first direction, and liquid storage communication grooves extending in a direction different from the first direction and communicating with the liquid storage main grooves, the communication recess extends to at least one of the liquid flow path communication groove and the liquid storage communication groove; This may be done.

[0041] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the communication portion includes a through-hole that penetrates the sheet main body and extends from the liquid flow path portion to the liquid storage portion. This may be done.

[0042] In addition, in the wick sheet for a vapor chamber according to the seventh solving means, the liquid flow path section has a plurality of liquid flow path mainstream grooves extending in a first direction and through which the liquid of the working fluid passes, and liquid flow path communication grooves extending in a direction different from the first direction and communicating with the liquid flow path mainstream grooves, the liquid flow path main groove further includes a liquid flow path intersection portion communicating with the liquid flow path communication groove, the liquid storage portion has a plurality of liquid storage main grooves extending in the first direction, and liquid storage communication grooves extending in a direction different from the first direction and communicating with the liquid storage main grooves, the liquid storage main groove further includes a liquid storage intersection portion communicating with the liquid storage communication groove, the through-hole extends to at least one of the liquid flow path intersection and the liquid storage intersection; This may be done.

[0043] Furthermore, as an eighth solution, the present invention provides: The first sheet and The second sheet, a vapor chamber including a wick sheet for a vapor chamber according to the seventh solution interposed between the first sheet and the second sheet; to provide.

[0044] In the vapor chamber according to the eighth solution, an evaporation region in which the working fluid evaporates; The liquid storage section is disposed in a region different from the evaporation region. This may be done.

[0045] In addition, in the vapor chamber according to the eighth solution, The working fluid has freeze-expansion properties. This may be done.

[0046] In addition, in the vapor chamber according to the eighth solution, an evaporation region in which the working fluid evaporates; The liquid reservoir is disposed in the evaporation region. This may be done.

[0047] Furthermore, the present invention provides, as a ninth solution, Housing and an electronic device contained within the housing; an electronic device comprising: a vapor chamber according to the eighth solution in thermal contact with the electronic device; to provide. [Effects of the Invention]

[0048] According to the present invention, it is possible to suppress performance degradation. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 1 is a schematic perspective view illustrating an electronic device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a top view showing the vapor chamber according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of the vapor chamber taken along line AA in FIG. [Figure 4] FIG. 4 is a top view of the lower sheet of FIG. [Figure 5] FIG. 5 is a bottom view of the upper sheet of FIG. [Figure 6] FIG. 6 is a top view of the wick sheet of FIG. [Figure 7] FIG. 7 is a bottom view of the wick sheet of FIG. [Figure 8A] FIG. 8A is a partially enlarged cross-sectional view of FIG. [Figure 8B] FIG. 8B is a partially enlarged cross-sectional view showing another example of FIG. 8A. [Figure 8C] FIG. 8C is a partially enlarged cross-sectional view showing another example of FIG. 8A. [Figure 9] FIG. 9 is a partially enlarged top view of the liquid flow path portion shown in FIG. [Figure 10] 10 is a partially enlarged bottom view of the liquid storage section shown in FIG. [Figure 11]FIG. 11 is a partial cross-sectional view taken along line BB in FIG. [Figure 12] FIG. 12 is a view for explaining a wick sheet preparation step in the method for manufacturing a vapor chamber according to the first embodiment. [Figure 13] FIG. 13 is a view for explaining an etching step in the method for manufacturing a vapor chamber according to the first embodiment. [Figure 14] FIG. 14 is a view for explaining a bonding step in the method for manufacturing a vapor chamber according to the first embodiment. [Figure 15] FIG. 15 is a partially enlarged top view showing a liquid flow path section as a first modified example. [Figure 16] FIG. 16 is a partially enlarged bottom view showing a liquid storage section as a first modified example. [Figure 17] FIG. 17 is a partially enlarged top view showing a liquid flow path section as a second modified example. [Figure 18] FIG. 18 is a partially enlarged bottom view showing a liquid storage section as a second modified example. [Figure 19] FIG. 19 is a partially enlarged bottom view showing a liquid storage section as a third modified example. [Figure 20] FIG. 20 is a partially enlarged bottom view showing a liquid storage section as a third modified example. [Figure 21] FIG. 21 is a partially enlarged bottom view showing a liquid storage section as a third modified example. [Figure 22] FIG. 22 is a bottom view of the wick sheet of FIG. 3 as a fifth modified example. [Figure 23] FIG. 23 is a bottom view of the wick sheet of FIG. 3 as a sixth modified example. [Figure 24] FIG. 24 is a bottom view showing a wick sheet in a vapor chamber according to the second embodiment of the present invention. [Figure 25] FIG. 25 is a partial cross-sectional view taken along line CC in FIG. [Figure 26]FIG. 26 is a schematic diagram for explaining the reflux of the working fluid in a general vapor chamber when the amount of heat generated by the electronic device is large. [Figure 27] FIG. 27 is a schematic diagram for explaining the reflux of the working fluid in a general vapor chamber when the amount of heat generated by the electronic device is small. DETAILED DESCRIPTION OF THE INVENTION

[0050] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings attached to this specification, the scale and aspect ratios of the actual objects have been appropriately changed and exaggerated for the sake of convenience in illustration and understanding.

[0051] Furthermore, the geometric conditions, physical characteristics, terms specifying the degree of a geometric condition or physical characteristic, and numerical values ​​indicating a geometric condition or physical characteristic used in this specification are not to be construed as being bound by strict meaning. These geometric conditions, physical characteristics, terms, and numerical values ​​are to be construed to include the range within which similar functionality can be expected. Examples of terms specifying geometric conditions include "length," "angle," "shape," and "arrangement." Examples of terms specifying geometric conditions include "parallel," "orthogonal," and "identical." Furthermore, to clarify the drawings, the shapes of multiple parts that can be expected to have similar functionality are depicted in a regular pattern. However, without being bound by strict meaning, the shapes of the parts may differ from each other as long as the functionality can be expected. Furthermore, in the drawings, boundary lines indicating the joining surfaces of components are shown as simple straight lines for convenience, but they 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.

[0052] (First embodiment) 1 to 21, a wick sheet for a vapor chamber, a vapor chamber, and an electronic device according to a first embodiment of the present invention will be described. The vapor chamber 1 in this embodiment is accommodated in a housing H of the electronic device E together with an electronic device D that generates heat, and is a device for cooling the electronic device D. Examples of the electronic device E include mobile terminals such as portable terminals and tablet terminals. Examples of the electronic device D include a central processing unit (CPU), a light-emitting diode (LED), or a power semiconductor. The electronic device D may also be referred to as a cooled device.

[0053] Here, an electronic device E equipped with a vapor chamber 1 according to this embodiment will first be described using a tablet terminal as an example. As shown in FIG. 1, the electronic device E includes a housing H, an electronic device D housed within the housing H, and a vapor chamber 1. In the electronic device E shown in FIG. 1, a touch panel display TD is provided on the front surface of the housing H. The vapor chamber 1 is housed within the housing H and is arranged so as to be in thermal contact with the electronic device D. This allows the vapor chamber 1 to receive heat generated by the electronic device D when the electronic device E is in use. The heat received by the vapor chamber 1 is released to the outside of the vapor chamber 1 via working fluids 2a and 2b, which will be described later. In this way, the electronic device D is effectively cooled. When the electronic device E is a tablet terminal, the electronic device D corresponds to a central processing unit or the like.

[0054] 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, and the working fluids 2a and 2b in the sealed space 3 repeatedly undergo phase changes to cool the electronic device D described above. Examples of the working fluids 2a and 2b include pure water, ethanol, methanol, acetone, and mixtures thereof. 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 the freeze-expansion working fluids 2a and 2b include pure water and aqueous solutions of pure water to which an additive such as alcohol has been added.

[0055] As shown in FIGS. 2 and 3, the vapor chamber 1 includes a lower sheet 10, an upper sheet 20, and a wick sheet 30 for the vapor chamber. The lower sheet 10 is an example of a first sheet. The upper sheet 20 is an example of a second sheet. The wick sheet 30 for the vapor chamber is interposed between the lower sheet 10 and the upper sheet 20. Hereinafter, the wick sheet for the vapor chamber will be simply referred to as the wick sheet 30. In this embodiment, the lower sheet 10, the wick sheet 30, and the upper sheet 20 are laminated in this order.

[0056] 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, and may be a rectangle as shown in FIG. 2. The planar shape of the vapor chamber 1 may be, for example, a rectangle with one side 1 cm and the other 3 cm, or a square with one side 15 cm. The planar dimensions of the vapor chamber 1 are arbitrary. In this embodiment, as an example, an example will be described in which the planar shape of the vapor chamber 1 is a rectangle with the X direction (described later) as the longitudinal direction. In this case, as shown in FIGS. 4 to 7, the lower sheet 10, the upper sheet 20, and the 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.

[0057] As shown in FIG. 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.

[0058] The evaporation region SR is a region that overlaps with the electronic device D in a planar view and is a region where the electronic 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 FIG. 2 ). Heat from the electronic device D is transferred to the evaporation region SR, and this heat causes the liquid working fluid to evaporate in the evaporation region SR. The heat from the electronic device D can be transferred not only to the region that overlaps with the electronic device D in a planar view, but also to the periphery of the region where the electronic device D overlaps. Therefore, the evaporation region SR includes the region that overlaps with the electronic device D and the periphery of the region 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 electronic device D and the surface that releases the received heat. The heat-receiving surface corresponds to the second upper sheet surface 20b of the upper sheet 20, which will be described later. The heat-releasing surface corresponds to the first lower sheet surface 10a of the lower sheet 10, which will be described later. For example, as shown in Figure 2, the state in which the vapor chamber 1 is viewed from above or below corresponds to a plan view. The gaseous working fluid is referred to as working vapor 2a, and the liquid working fluid is referred to as working liquid 2b.

[0059] The condensation region CR is a region that does not overlap with the electronic device D in a plan view, and is a region where the working vapor 2a mainly releases heat and condenses. The condensation region CR can also be said to be a 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.

[0060] When the vapor chamber 1 is installed inside a tablet terminal, the up-down relationship may be lost depending on the orientation of the tablet terminal. However, in this embodiment, for convenience, the sheet that receives heat from the electronic device D will be referred to as the upper sheet 20, and the sheet that dissipates the received heat will be referred to as the lower sheet 10. For this reason, the configuration of the vapor chamber 1 will be described with the lower sheet 10 positioned on the lower side and the upper sheet 20 positioned on the upper side.

[0061] As shown in FIG. 3, the lower sheet 10 has a first lower sheet surface 10a provided on the side opposite the wick sheet 30 and a second lower sheet surface 10b provided on the side opposite the first lower sheet surface 10a. The second lower sheet surface 10b is provided on the wick sheet 30 side. The lower sheet 10 may be formed flat overall. The lower sheet 10 may have a constant thickness overall. A housing member Ha constituting a part of the housing H described above 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.

[0062] As shown in FIG. 3, the upper sheet 20 has a first upper sheet surface 20a provided on the wick sheet 30 side and a second upper sheet surface 20b provided on the opposite side to the first upper sheet surface 20a. The first upper sheet surface 20a is provided on the wick sheet 30 side. The upper sheet 20 may be formed to be generally flat. The upper sheet 20 may have a uniform thickness overall. The electronic 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.

[0063] As shown in Fig. 3, the wick sheet 30 includes a sheet body 31, a vapor flow path section 50 provided in the sheet body 31, a liquid flow path section 60, and a liquid storage section 70. The sheet body 31 has a first body surface 31a and a second body surface 31b provided on the opposite side to the first body surface 31a. The first body surface 31a is disposed on the side of the lower sheet 10. The second body surface 31b is disposed on the side of the upper sheet 20. The vapor flow path section 50, the liquid flow path section 60, and the liquid storage section 70 form the sealed space 3 described above.

[0064] The second lower sheet surface 10b of the lower sheet 10 and the first main body surface 31a of the sheet main body 31 may be diffusion bonded. The second lower sheet surface 10b and the first main body surface 31a may be permanently bonded to each other. Similarly, the first upper sheet surface 20a of the upper sheet 20 and the second main body surface 31b of the sheet main body 31 may be diffusion bonded. The first upper sheet surface 20a and the second main body surface 31b may be permanently bonded to each other. Note that the lower sheet 10, the upper sheet 20, and the wick sheet 30 may be bonded by other methods such as brazing, instead of diffusion bonding, as long as they are permanently bonded. Note that the term "permanently bonded" is not limited to a strict meaning and is used to mean that they are bonded to an extent that the hermeticity of the sealed space 3 can be maintained when the vapor chamber 1 is operating. It is sufficient that the lower sheet 10 and the wick sheet 30 are permanently joined together so that the bond between the lower sheet 10 and the wick sheet 30 can be maintained during operation of the vapor chamber 1. It is sufficient that the upper sheet 20 and the wick sheet 30 are permanently joined together so that the bond between the upper sheet 20 and the wick sheet 30 can be maintained during operation of the vapor chamber 1.

[0065] The sheet body 31 of the wick sheet 30 according to this embodiment includes a frame portion 32 and a plurality of land portions 33. As shown in FIGS. 3, 6, and 7, the frame portion 32 is formed in a rectangular frame shape in plan view. The land portions 33 are provided within the frame portion 32. The frame portion 32 and the land portions 33 are portions where the material of the wick sheet 30 remains without being etched in the etching process described below. A steam flow path portion 50 is defined inside the frame portion 32. That is, the working steam 2a flows inside the frame portion 32 and around the land portions 33.

[0066] In this embodiment, the land portions 33 may extend in an elongated shape with the X direction as the longitudinal direction in a plan view. The planar shape of the land portions 33 may be an elongated rectangle. The X direction is an example of a first direction. The X direction corresponds to the left-right direction in FIG. 6. The land portions 33 are equally spaced apart in the Y direction. The Y direction is an example of a second direction. The Y direction corresponds to the up-down direction in FIG. 6. The land portions 33 may be arranged parallel to each other. The working steam 2a flows around each land portion 33 and is 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. 8A) may be, for example, 100 μm to 1500 μm. Here, the width w1 of the land portion 33 is the dimension of the land portion 33 in the Y direction. The width w1 refers to the dimension at a position in the thickness direction of the wick sheet 30 where a penetration portion 34, which will be described later, is present.

[0067] 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. A wall surface 53a of the lower vapor flow path recess 53 and a wall surface 54a of the upper vapor flow path recess 54 (described later) form the side walls of the land portion 33. The first main body surface 31a and the second main body surface 31b of the sheet main body 31 may be formed flat across the frame body 32 and each land portion 33.

[0068] The steam flow path portion 50 is an example of a through space that penetrates the sheet main body 31. The steam flow path portion 50 is a flow path through which the working steam 2a mainly passes. The steam flow path portion 50 penetrates from the first main body surface 31a to the second main body surface 31b.

[0069] As shown in FIGS. 6 and 7 , the steam flow path section 50 in this embodiment has a first steam path 51 and a plurality of second steam paths 52. The first steam path 51 is formed between the frame body section 32 and the land section 33. The first steam path 51 is formed inside the frame body section 32 and continuously outside the land section 33. The first steam path 51 has a planar shape of a rectangular frame. The second steam path 52 is formed between adjacent land sections 33. The second steam path 52 has a planar shape of an elongated rectangle. The steam flow path section 50 is partitioned into the first steam path 51 and the plurality of second steam paths 52 by the plurality of land sections 33.

[0070] 3, the first steam passage 51 and the second steam passage 52 extend from the first main body surface 31a to the second main body surface 31b of the sheet main body 31. The first steam passage 51 and the second steam passage 52 are each formed by a lower steam passage recess 53 provided in the first lower sheet surface 10a and an upper steam passage recess 54 provided in the upper sheet surface 20b. The lower steam passage recess 53 and the upper steam passage recess 54 are in communication with each other, and the first steam passage 51 and the second steam passage 52 of the steam passage section 50 extend from the first main body surface 31a to the second main body surface 31b.

[0071] The lower steam flow path recess 53 is formed by etching from the first main body surface 31a of the wick sheet 30 in an etching step described below. The lower steam flow path recess 53 is formed in a concave shape on the first main body surface 31a. As a result, the lower steam flow path recess 53 has a curved wall surface 53a, as shown in FIG. 8A . This wall surface 53a defines the lower steam flow path recess 53 and is curved in a shape that bulges toward the second main body surface 31b. Such a lower steam flow path recess 53 constitutes a part (lower half) of the first steam passage 51 and a part (lower half) of the second steam passage 52.

[0072] The upper steam flow path recess 54 is formed by etching from the second main body surface 31b of the wick sheet 30 in an etching step described below. The upper steam flow path recess 54 is formed in a concave shape on the second main body surface 31b. As a result, the upper steam flow path recess 54 has a curved wall surface 54a, as shown in FIG. 8A . This wall surface 54a defines the upper steam flow path recess 54 and is curved in a shape that bulges toward the first main body surface 31a. Such an upper steam flow path recess 54 constitutes a part (upper half) of the first steam path 51 and a part (upper half) of the second steam path 52.

[0073] As shown in FIG. 8A , the wall surface 53 a of the lower steam flow path recess 53 and the wall surface 54 a of the upper steam flow path recess 54 are connected to form the through-port 34. The wall surfaces 53 a and 54 a are each curved toward the through-port 34. This allows the lower steam flow path recess 53 and the upper steam flow path recess 54 to communicate with each other. In this embodiment, the planar shape of the through-port 34 in the first steam passage 51 is a rectangular frame, similar to the first steam passage 51. The planar shape of the through-port 34 in the second steam passage 52 is an elongated rectangular, similar to the second steam passage 52. The wall surface 53 a of the lower steam flow path recess 53 and the wall surface 54 a of the upper steam flow path recess 54 may join together and be defined by a ridge line. As shown in FIG. 8A , the ridge line may be formed to extend inward of the steam passages 51 and 52. The planar area of ​​the first steam passage 51 is minimum at this through portion 34, and the planar area of ​​the second steam passage 52 is also minimum. The width w2 of such through portion 34 (see FIG. 8A) may be, for example, 400 μm to 1600 μm. Here, the width w2 of the through portion 34 corresponds to the gap between the land portions 33 adjacent to each other in the Y direction.

[0074] The position of the through-hole 34 in the Z direction may be an intermediate position between the first lower sheet surface 10a and the upper sheet surface 20b. Alternatively, the position of the through-hole 34 may be a position shifted downward or upward from the intermediate position. As long as the lower steam flow path recess 53 and the upper steam flow path recess 54 are in communication with each other, the position of the through-hole 34 in the Z direction is arbitrary.

[0075] In the present embodiment, the cross-sectional shapes of the first steam passage 51 and the second steam passage 52 are formed to include the through-holes 34 defined by ridges formed to protrude inward, but this is not limited to this. For example, the cross-sectional shapes of the first steam passage 51 and the second steam passage 52 may be trapezoidal, rectangular, or barrel-shaped.

[0076] The steam flow path section 50 including the first steam path 51 and the second steam path 52 configured in this manner constitutes a part of the above-mentioned sealed space 3. As shown in Fig. 3, the steam flow path section 50 according to this embodiment is defined mainly by the lower sheet 10, the upper sheet 20, and the frame portion 32 and land portion 33 of the above-mentioned sheet main body 31. Each of the steam paths 51, 52 has a relatively large flow path cross-sectional area so that the working steam 2a can pass through.

[0077] 3, for clarity of the drawing, the first steam passage 51 and the second steam passage 52 are shown enlarged. The number and arrangement of these steam passages 51, 52 are different from those in FIGS. 2, 6, and 7.

[0078] Although not shown, multiple support portions for supporting the land portion 33 on the frame portion 32 may be provided within the steam flow path portion 50. Support portions for supporting adjacent land portions 33 may also be provided. These support portions may be provided on both sides of the land portion 33 in the X direction or on both sides of the land portion 33 in the Y direction. The support portions are preferably formed so as not to impede the flow of the working steam 2a diffusing through the steam flow path portion 50. For example, the support portions may be disposed on one of the first main body surface 31a and the second main body surface 31b of the sheet main body 31 of the wick sheet 30, with a space forming a steam flow path recess formed on the other side. This allows the thickness of the support portions to be thinner than the thickness of the sheet main body 31, preventing the first steam path 51 and the second steam path 52 from being separated in the X direction and the Y direction.

[0079] As shown in FIGS. 6 and 7, alignment holes 35 may be provided at the four corners of the sheet body 31 of the wick sheet 30.

[0080] 2, the vapor chamber 1 may further include an injection part 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 part 4 is disposed on the evaporation region SR side. The injection part 4 protrudes outward from the edge on the evaporation region SR side.

[0081] More specifically, the injection section 4 may include a lower injection protrusion 11, an upper injection protrusion 21, and a wick sheet injection protrusion 36. As shown in FIG. 4, the lower injection protrusion 11 is a portion that constitutes the lower sheet 10. As shown in FIG. 5, the upper injection protrusion 21 is a portion that constitutes the upper sheet 20. As shown in FIGS. 6 and 7, the wick sheet injection protrusion 36 is a portion that constitutes the sheet main body 31. An injection flow path 37 is formed in the wick sheet injection protrusion 36. This injection flow path 37 extends from the first main body surface 31a to the second main body surface 31b of the sheet main body 31 and penetrates the sheet main body 31 (more specifically, the wick sheet injection protrusion 36) in the Z direction. The injection flow path 37 also communicates with the vapor flow path section 50. The working fluid 2b is injected into the sealed space 3 through this injection flow path 37. Depending on the arrangement of the liquid flow path section 60, the injection flow path 37 may be connected to the liquid flow path section 60. The upper and lower surfaces of the wick sheet injection protrusion 36 are formed flat. The upper surface of the lower injection protrusion 11 and the lower surface of the upper injection protrusion 21 are also formed flat. The planar shapes of the injection protrusions 11, 21, and 38 may be the same.

[0082] In this embodiment, the injection portion 4 is provided on one edge of a pair of edges in the X direction of the vapor chamber 1. However, this is not limited to this, and the injection portion 4 can be provided at any position. Furthermore, the injection flow path 37 provided in the wick sheet injection protrusion 36 does not need to penetrate the sheet main body 31 as long as it can inject the working fluid 2b. In this case, the injection flow path 37 communicating with the vapor flow path portion 50 can be formed by etching only from one of the first main body surface 31a and the second main body surface 31b of the sheet main body 31.

[0083] As shown in FIGS. 3, 6, and 8A, the liquid flow path portion 60 is provided on the second main body surface 31b of the sheet main body 31 of the wick sheet 30. The liquid flow path portion 60 may be a flow path through which the working fluid 2b mainly passes. This liquid flow path portion 60 constitutes a part of the sealed space 3 described above. The liquid flow path portion 60 communicates with the vapor flow path portion 50. The liquid flow path portion 60 is configured as a capillary structure for transporting the working fluid 2b to the evaporation region SR. The liquid flow path portion 60 may also be referred to as a wick. In this embodiment, the liquid flow path portion 60 is provided on the second main body surface 31b of each land portion 33 of the wick sheet 30. The liquid flow path portion 60 may be formed over the entire second main body surface 31b of each land portion 33. The liquid flow path portion 60 does not have to be provided on the first main body surface 31a of each land portion 33.

[0084] As shown in FIG. 9 , the liquid flow path section 60 is an example of a first groove assembly. More specifically, the liquid flow path section 60 includes a plurality of liquid flow path mainstream grooves 61 and a plurality of liquid flow path communication grooves 65. The liquid flow path mainstream groove 61 is an example of a first mainstream groove. The liquid flow path communication groove 65 is an example of a first communication groove. The liquid flow path mainstream groove 61 and the liquid flow path communication groove 65 are grooves through which the working fluid 2b passes. The liquid flow path communication groove 65 communicates with the liquid flow path mainstream groove 61.

[0085] As shown in FIG. 9, each liquid flow path mainstream groove 61 extends in the X direction. Each liquid flow path mainstream groove 61 has a flow path cross-sectional area that allows the working fluid 2b to flow mainly by capillary action. The flow path cross-sectional area of ​​each liquid flow path mainstream groove 61 is smaller than the flow path cross-sectional area of ​​each vapor passage 51, 52. As a result, each liquid flow path mainstream groove 61 is configured to transport the working fluid 2b condensed from the working vapor 2a to the evaporation region SR. Each liquid flow path mainstream groove 61 may be arranged at equal intervals in the Y direction, which is perpendicular to the X direction.

[0086] The liquid flow path main grooves 61 are formed by etching from the second main body surface 31b of the sheet body 31 of the wick sheet 30 in an etching process described below. As a result, the liquid flow path main grooves 61 have curved wall surfaces 62, as shown in Fig. 8A. These wall surfaces 62 define the liquid flow path main grooves 61 and are curved in a shape that bulges toward the first main body surface 31a.

[0087] As shown in Figures 8A and 9, the width w3 of the liquid flow path mainstream groove 61 may be, for example, 5 µm to 150 µm. 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 corresponds to the dimension in the Y direction. Also, as shown in Figure 8A, the depth h1 of the liquid flow path mainstream groove 61 may be, for example, 3 µm to 150 µm. The depth h1 corresponds to the dimension in the Z direction.

[0088] 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 extends in the Y direction. The liquid flow path communication grooves 65 are formed perpendicular to the liquid flow path mainstream grooves 61. Some liquid flow path communication grooves 65 connect adjacent liquid flow path mainstream grooves 61 to each other. Other liquid flow path communication grooves 65 connect the first vapor passage 51 or the second vapor passage 52 to the liquid flow path mainstream groove 61. In other words, the liquid flow path communication groove 65 extends from the edge of the land portion 33 in the Y direction to the liquid flow path mainstream groove 61 adjacent to that edge. In this way, the first vapor passage 51 and the liquid flow path mainstream groove 61 are connected to each other, and the second vapor passage 52 and the liquid flow path mainstream groove 61 are connected to each other.

[0089] The liquid flow path communication groove 65 has a flow path cross-sectional area through which the working fluid 2b flows mainly by capillary action. The flow path cross-sectional area of ​​the liquid flow path communication groove 65 is smaller than the flow path cross-sectional area of ​​the vapor passages 51, 52. The liquid flow path communication grooves 65 may be arranged at equal intervals in the X direction.

[0090] The liquid flow path connecting groove 65 is formed by etching, similar to the liquid flow path mainstream groove 61. The liquid flow path connecting groove 65 has a wall surface (not shown) formed in a curved shape, similar to the liquid flow path mainstream groove 61. As shown in FIG. 9 , the width w4 of the liquid flow path connecting groove 65 may be equal to the width w3 of the liquid flow path mainstream groove 61. However, the width w4 may be greater than or less than the width w3. The width w4 corresponds to the dimension in the X direction. The depth of the liquid flow path connecting groove 65 may be equal to the depth h1 of the liquid flow path mainstream groove 61. However, the depth of the liquid flow path connecting groove 65 may be greater than or less than the depth h1.

[0091] As shown in FIG. 9 , a convex portion row 63 is provided between adjacent liquid flow path mainstream grooves 61. Each convex portion row 63 includes a plurality of convex portions 64 arranged in the X direction. The convex portions 64 are an example of a liquid flow path protrusion. The convex portions 64 are provided within the liquid flow path section 60. The convex portions 64 protrude from the sheet main body 31 and abut against the upper sheet 20. Each convex portion 64 is formed in a rectangular shape with the X direction as its longitudinal direction in a plan view. A liquid flow path mainstream groove 61 is interposed between adjacent convex portions 64 in the Y direction. A liquid flow path communication groove 65 is interposed between adjacent convex portions 64 in the X direction. The liquid flow path communication groove 65 extends in the Y direction and connects adjacent liquid flow path mainstream grooves 61 in the Y direction. This allows the working fluid 2b to move back and forth between these liquid flow path mainstream grooves 61.

[0092] 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, the planar shape of the protrusions 64 is rectangular, as shown in Fig. 9. The planar shape of the protrusions 64 corresponds to the planar shape of the sheet main body 31 at the position of the second main body surface 31b.

[0093] In this embodiment, the protrusions 64 are arranged in a staggered pattern. More specifically, the protrusions 64 of the protrusion rows 63 adjacent to each other in the Y direction are arranged so as to be shifted from each other in the X direction. This shift may be half the arrangement pitch of the protrusions 64 in the X direction. The width w5 of the protrusions 64 may be, for example, 5 μm to 500 μm. The width w5 of the protrusions 64 refers to the dimension on the second main body surface 31b. The width w5 corresponds to the dimension in the Y direction. Note that 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 FIG. 19 ).

[0094] The liquid flow path mainstream groove 61 includes a liquid flow path intersection 66. The liquid flow path intersection 66 is an example of a first intersection. The liquid flow path intersection 66 is a portion of the liquid flow path mainstream groove 61 that communicates with the liquid flow path communication groove 65. At the liquid flow path intersection 66, the liquid flow path mainstream groove 61 and the liquid flow path communication groove 65 communicate in a T-shape. This prevents the liquid flow path communication groove 65 on the other side from communicating with the liquid flow path mainstream groove 61 at the liquid flow path intersection 66, where the liquid flow path mainstream groove 61 communicates with the liquid flow path communication groove 65 on the other side. This prevents the wall surface 62 of the liquid flow path mainstream groove 61 from being cut out on both sides at the liquid flow path intersection 66, leaving one side of the wall surface 62 intact. For example, at one liquid flow path intersection 66, it is possible to prevent the upper liquid flow path communication groove 65 and the lower liquid flow path communication groove 65 in FIG. 9 from communicating with the liquid flow path mainstream groove 61. 9 at the liquid flow path intersection 66. This makes it possible to impart capillary action to the working fluid in the liquid flow path main groove 61, even at the liquid flow path intersection 66. This makes it possible to prevent a decrease in the propulsion force of the working fluid 2b toward the evaporation region SR at the liquid flow path intersection 66.

[0095] As shown in FIGS. 3, 7, and 8A, the liquid storage section 70 is provided on the first main body surface 31a of the sheet body 31 of the wick sheet 30. The liquid storage section 70 may be a section that mainly stores the working fluid 2b. This liquid storage section 70 constitutes a part of the sealed space 3 described above. The liquid storage section 70 communicates with the vapor flow path section 50 and also communicates with the liquid flow path section 60 via the vapor flow path section 50. In this embodiment, the liquid storage section 70 is provided on the first main body surface 31a of each land section 33 of the wick sheet 30.

[0096] As shown in FIGS. 7 and 11 , the liquid reservoir 70 according to this embodiment may be disposed on one side of the land 33 in the X direction. The liquid reservoir 70 may be formed on the side of the land 33 relative to the center in the X direction. The liquid reservoir 70 may be disposed on the evaporation region SR side, or may be disposed on the left side of the land 33 as shown in FIG. 7 . More specifically, the liquid reservoir 70 is continuously formed from the edge of the land 33 on the evaporation region SR side to a predetermined position toward the other edge in the X direction. In FIG. 7 , the liquid reservoir 70 is formed from the left edge toward the right edge to a predetermined position. The liquid reservoir 70 according to this embodiment may be disposed in the evaporation region SR. However, this is not a limitation, and a portion of the liquid reservoir 70 may extend outside the evaporation region SR. When at least a portion of the liquid reservoir 70 is disposed in the evaporation region SR, the working fluid 2b stored in the liquid reservoir 70 is more likely to evaporate due to heat from the electronic device D. The liquid reservoir 70 may be disposed in a region overlapping with the electronic device D.

[0097] As shown in FIG. 10 , the liquid storage section 70 is an example of a second groove assembly. More specifically, the liquid storage section 70 includes a plurality of liquid storage main grooves 71 and a plurality of liquid storage communication grooves 75. The liquid storage main groove 71 is an example of a second main groove. The liquid storage communication groove 75 is an example of a second communication groove. The liquid storage main groove 71 and the liquid storage communication groove 75 are grooves through which the working fluid 2b passes. The liquid storage communication groove 75 is in communication with the liquid storage main groove 71.

[0098] As shown in FIG. 10 , each liquid storage mainstream groove 71 extends in the X direction. As shown in FIGS. 7 and 11 , the liquid storage mainstream groove 71 is continuously formed from the edge of the land portion 33 on the evaporation region SR side in the X direction toward the other edge to a predetermined position. The liquid storage mainstream groove 71 defines the X direction range of the liquid storage portion 70. The liquid storage mainstream groove 71 has a flow path cross-sectional area through which the working fluid 2b flows mainly by capillary action. The flow path cross-sectional area of ​​the liquid storage mainstream groove 71 is smaller than the flow path cross-sectional area of ​​the vapor passages 51, 52. However, the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 may be larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61 described above. The capillary force acting on the working fluid 2b in the liquid storage mainstream groove 71 may be smaller than the capillary force acting on the working fluid 2b in the liquid flow path mainstream groove 61. In this way, the liquid storage main grooves 71 can draw the working fluid 2b into the liquid storage portion 70 and ensure the storage amount of the working fluid 2b. The liquid storage main grooves 71 may be arranged at equal intervals in the Y direction perpendicular to the X direction.

[0099] The liquid storage main groove 71 is formed by etching from the first main body surface 31a of the sheet body 31 of the wick sheet 30 in an etching process described below. As a result, the liquid storage main groove 71 has a curved wall surface 72, as shown in Fig. 8A. This wall surface 72 defines the liquid storage main groove 71 and is curved in a shape that bulges toward the second main body surface 31b.

[0100] As shown in FIGS. 8A and 10, the width w6 of the liquid storage mainstream groove 71 may be larger than the width w3 of the liquid flow path mainstream groove 61 described above. The width w6 may be, for example, 10 μm to 250 μm. The width w6 of the liquid storage mainstream groove 71 refers to the dimension at the first main body surface 31a. The width w6 corresponds to the dimension in the Y direction. Also, as shown in FIG. 8A, the depth h2 of the liquid storage mainstream groove 71 may be larger than the depth h1 of the liquid flow path mainstream groove 61 described above. The depth h2 may be, for example, 5 μm to 200 μm. The depth h2 corresponds to the dimension in the Z direction.

[0101] As shown in FIG. 10 , each liquid storage communication groove 75 extends in a direction different from the X direction. In this embodiment, each liquid storage communication groove 75 extends in the Y direction. The liquid storage communication grooves 75 are formed perpendicular to the liquid storage mainstream grooves 71. Some liquid storage communication grooves 75 connect adjacent liquid storage mainstream grooves 71 to each other. Other liquid storage communication grooves 75 connect the first vapor passage 51 or the second vapor passage 52 to the liquid storage mainstream groove 71. That is, the liquid storage communication groove 75 extends from the edge of the land portion 33 in the Y direction to the liquid storage mainstream groove 71 adjacent to that edge. In this way, the first vapor passage 51 and the liquid storage mainstream groove 71 are connected to each other, and the second vapor passage 52 and the liquid storage mainstream groove 71 are connected to each other.

[0102] The liquid storage communication groove 75 has a flow path cross-sectional area that allows the working liquid 2b to flow primarily due to capillary action. The flow path cross-sectional area of ​​the liquid storage communication groove 75 is smaller than the flow path cross-sectional area of ​​the vapor passages 51, 52. However, the flow path cross-sectional area of ​​the liquid storage communication groove 75 may be larger than the flow path cross-sectional area of ​​the liquid flow path communication groove 65 described above. The capillary force acting on the working liquid 2b in the liquid storage communication groove 75 may be smaller than the capillary force acting on the working liquid 2b in the liquid flow path communication groove 65. In this way, the liquid storage communication groove 75 can draw the working liquid 2b into the liquid storage section 70 and ensure a sufficient storage amount of the working liquid 2b. The liquid storage communication grooves 75 may be arranged at equal intervals in the X direction.

[0103] The liquid storage communication groove 75 is formed by etching, similar to the liquid storage mainstream groove 71. The liquid storage communication groove 75 has a wall surface (not shown) formed in a curved shape similar to the liquid storage mainstream groove 71. As shown in FIG. 10, the width w7 of the liquid storage communication groove 75 may be equal to the width w6 of the liquid storage mainstream groove 71. However, the width w7 may be greater or smaller than the width w6. The width w7 corresponds to the dimension in the X direction. The depth of the liquid storage communication groove 75 may be equal to the depth h2 of the liquid storage mainstream groove 71. However, the depth of the liquid storage communication groove 75 may be greater or smaller than the depth h2.

[0104] As shown in FIG. 10 , a convex portion row 73 is provided between adjacent liquid storage main grooves 71. Each convex portion row 73 includes a plurality of convex portions 74 arranged in the X direction. The convex portions 74 are an example of a liquid storage protrusion. The convex portions 74 are provided within the liquid storage portion 70. The convex portions 74 protrude from the sheet main body 31 and abut against the lower sheet 10. Each convex portion 74 is formed in a rectangular shape with the X direction as its longitudinal direction in a plan view. A liquid storage main groove 71 is interposed between adjacent convex portions 74 in the Y direction. A liquid storage communication groove 75 is interposed between adjacent convex portions 74 in the X direction. The liquid storage communication groove 75 extends in the Y direction and connects adjacent liquid storage main grooves 71 in the Y direction. This allows the working fluid 2b to flow between these liquid storage main grooves 71.

[0105] The protrusions 74 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 planar shape of the protrusions 74 is rectangular, as shown in Fig. 10. The planar shape of the protrusions 74 corresponds to the planar shape of the first main body surface 31a of the sheet main body 31.

[0106] In this embodiment, the protrusions 74 are arranged in a staggered pattern. More specifically, the protrusions 74 of adjacent protrusion rows 73 are arranged so as to be shifted from each other in the X direction. This shift may be half the arrangement pitch of the protrusions 74 in the X direction. The width w8 of the protrusions 74 may be, for example, 10 μm to 100 μm. The width w8 of the protrusions 74 refers to the dimension on the first main body surface 31a. The width w8 corresponds to the dimension in the Y direction. Note that the arrangement of the protrusions 74 is not limited to a staggered pattern, and they may be arranged in parallel. In this case, the protrusions 74 of the protrusion rows 73 adjacent to each other in the Y direction are also aligned in the X direction (see FIG. 19 ).

[0107] In this way, the width w6 of the liquid storage mainstream groove 71 may be larger than the width w3 of the liquid flow path mainstream groove 61. The width w6 corresponds to the gap between a pair of adjacent protrusions 74 in the Y direction. Furthermore, the width w6 of the liquid storage mainstream groove 71 may be smaller than the width w2 of the through portion 34. The width w2 corresponds to the gap between a pair of adjacent land portions 33 in the Y direction.

[0108] In the present embodiment, as described above, the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 of the liquid storage portion 70 is larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61 of the liquid flow path portion 60. To satisfy this relationship of flow path cross-sectional areas, in the example shown in FIG. 8A , the width w6 of the liquid storage mainstream groove 71 is larger than the width w3 of the liquid flow path mainstream groove 61, and the depth h2 of the liquid storage mainstream groove 71 is larger than the depth h1 of the liquid flow path mainstream groove 61. However, this is not limiting, and as long as the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 is larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61, the relationship between the width and the depth is arbitrary. For example, as shown in FIG. 8B , if the width w6 is larger than the width w3, the depth h2 may be equal to the depth h1. Even in this case, the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 can be larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61. Furthermore, as shown in FIG. 8C , if the depth h2 is larger than the depth h1, the width w6 may be equal to the width w3. Even in this case, the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 can be made larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61. In this specification, the flow path cross-sectional area of ​​a groove corresponds to the area occupied by the groove in a cross section taken along a direction perpendicular to the direction in which the groove extends. For example, the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61 corresponds to the area occupied by the groove 61 (or the space defined by the wall surface 62 of the groove 61) in a cross section of the liquid flow path mainstream groove 61 taken along the Y direction.

[0109] Furthermore, the number of liquid storage mainstream grooves 71 provided in the land portion 33 may be smaller than the number of liquid flow path mainstream grooves 61 provided in the land portion 33. In this embodiment, the land portion 33 extends in the X direction and has an elongated rectangular shape. The width of the land portion 33 on the first main body surface 31a is equal to the width of the land portion 33 on the second main body surface 31b. In this case, the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 can be larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61.

[0110] The liquid storage mainstream groove 71 includes a liquid storage intersection 76. The liquid storage intersection 76 is an example of a second intersection. The liquid storage intersection 76 is a portion of the liquid storage mainstream groove 71 that communicates with the liquid storage communication groove 75. At the liquid storage intersection 76, the liquid storage mainstream groove 71 and the liquid storage communication groove 75 communicate in a T-shape. This prevents the liquid storage communication groove 75 on the other side from communicating with the liquid storage mainstream groove 71 at a liquid storage intersection 76 where the liquid storage mainstream groove 71 communicates with the liquid storage communication groove 75 on the other side. This prevents the wall surface 72 of the liquid storage mainstream groove 71 from being cut out on both sides at the liquid storage intersection 76, leaving one side of the wall surface 72 intact. For example, at one liquid storage intersection 76, the upper liquid storage communication groove 75 and the lower liquid storage communication groove 75 in FIG. 10 are prevented from communicating with the liquid storage mainstream groove 71. In this case, it is possible to prevent both the upper wall surface 72 and the lower wall surface 72 in Figure 10 from being cut out at the liquid storage intersection 76. This allows capillary action to be imparted to the working fluid in the liquid storage main groove 71 at the liquid storage intersection 76 as well.

[0111] The materials constituting the lower sheet 10, the upper sheet 20, and the wick sheet 30 are not particularly limited as long as they have good thermal conductivity. However, the lower sheet 10, the upper sheet 20, and the 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 and 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.

[0112] 3 may be, for example, 100 μm to 1000 μm. By making the thickness t1 of the vapor chamber 1 100 μm or more, the vapor channel section 50 can be properly secured. This allows the vapor chamber 1 to properly function. On the other hand, by making the thickness t1 1000 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick.

[0113] The thickness t2 of the lower sheet 10 may be, for example, 6 μm to 100 μm. By setting the thickness t2 of the lower sheet 10 to 6 μm or more, the mechanical strength of the lower sheet 10 can be ensured. On the other hand, by setting the thickness t2 of the lower sheet 10 to 100 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick. Similarly, the thickness t3 of the upper sheet 20 may be set to be 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.

[0114] The thickness t4 of the wick sheet 30 may be, for example, 50 μm to 400 μm. By making the thickness t4 of the wick sheet 30 50 μm or more, the vapor channel portion 50 can be properly secured. This allows the vapor chamber 1 to properly function. On the other hand, by making the thickness t4 400 μm or less, the thickness t1 of the vapor chamber 1 can be prevented from becoming too thick.

[0115] Next, a method for manufacturing the vapor chamber 1 of this embodiment configured as described above will be described with reference to Figures 12 to 14. Figures 12 to 14 show cross sections similar to the cross section of Figure 3.

[0116] First, the process of manufacturing the wick sheet 30 will be described.

[0117] First, as shown in Fig. 12, a flat metal material sheet M is prepared as a preparation step. The metal material sheet M includes a first material surface Ma and a second material surface Mb. The metal material sheet M may be formed from a rolled material having a desired thickness.

[0118] After the preparation step, in the etching step, the metal material sheet M is etched from the first material surface Ma and the second material surface Mb as shown in Fig. 13. As a result, a vapor flow path portion 50, a liquid flow path portion 60, and a liquid storage portion 70 are formed in the metal material sheet M.

[0119] 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 a vapor flow path portion 50, a liquid flow path portion 60, and a liquid storage portion 70 as shown in FIG. 13. Note that, 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 can be used as the etching solution.

[0120] 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 steps. Furthermore, the vapor flow path portion 50, the liquid flow path portion 60, and the liquid storage portion 70 may be formed by etching simultaneously, or may be formed in separate steps.

[0121] 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. That is, the edge of the wick sheet 30 is formed.

[0122] In this manner, the wick sheet 30 according to this embodiment is obtained.

[0123] After the manufacturing process of the wick sheet 30, the lower sheet 10, the upper sheet 20, and the wick sheet 30 are joined together in a joining process as shown in Fig. 14. The lower sheet 10 and the upper sheet 20 may be formed from rolled material having a desired planar shape and a desired thickness.

[0124] More specifically, first, the lower sheet 10, the wick sheet 30, and the upper sheet 20 are laminated in this order. In this case, the first main body surface 31a of the wick sheet 30 is placed on the second lower sheet surface 10b of the lower sheet 10, and the first upper sheet surface 20a of the upper sheet 20 is placed on the second main body surface 31b of the wick sheet 30. At this time, the alignment holes 12 of the lower sheet 10, the alignment holes 35 of the wick sheet 30, and the alignment holes 22 of the upper sheet 20 are used to align the sheets 10, 20, and 30.

[0125] Next, the lower sheet 10, the wick sheet 30, and the 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.

[0126] Next, the lower sheet 10, the wick sheet 30, and the upper sheet 20 are permanently bonded together by diffusion bonding. Diffusion bonding is a method of bonding the lower sheet 10, the wick sheet 30, and the upper sheet 20 together by applying pressure and heat in the stacking direction in a controlled atmosphere, such as a vacuum or an inert gas atmosphere, to utilize atomic diffusion that occurs at the bonding surfaces. When pressure is applied, the lower sheet 10 and the wick sheet 30 are in close contact with each other, and the wick sheet 30 and the upper sheet 20 are also in close contact with each other. Diffusion bonding heats the materials of the sheets 10, 20, and 30 to a temperature close to, but lower than, their melting points, preventing the sheets 10, 20, and 30 from melting and deforming. More specifically, the first main body surface 31a of the frame portion 32 and each land portion 33 of the wick sheet 30 is diffusion bonded to the second lower sheet surface 10b of the lower sheet 10. Furthermore, 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, a liquid flow path portion 60, and a liquid storage portion 70 between the lower sheet 10 and the upper sheet 20. At this stage, the above-mentioned injection flow path 37 of the sealed space 3 is not sealed. In the above-mentioned injection portion 4, the lower injection protrusion 11 of the lower sheet 10 and the wick sheet injection protrusion 36 of the wick sheet 30 are diffusion bonded. Furthermore, the wick sheet injection protrusion 36 is diffusion bonded to the upper injection protrusion 21 of the upper sheet 20.

[0127] After the joining process, the working fluid 2b is injected into the sealed space 3 from the injection section 4. At this time, the amount of the working fluid 2b injected may be greater than the total volume of the space formed by each liquid flow path main groove 61 and each liquid flow path connecting groove 65 of the liquid flow path section 60.

[0128] Thereafter, the above-mentioned injection flow path 37 is sealed. For example, injection portion 4 may be irradiated with a laser beam so that injection portion 4 is partially melted and seals injection flow path 37. This blocks communication between sealed space 3 and the outside, and a sealed space 3 is obtained in which working fluid 2b is sealed. This prevents working fluid 2b in sealed space 3 from leaking to the outside. Note that injection flow path 37 can be sealed by crimping injection portion 4 (or by pressing and plastically deforming it) or by brazing.

[0129] In this manner, the vapor chamber 1 according to this embodiment is obtained.

[0130] Next, a method for operating the vapor chamber 1, that is, a method for cooling the electronic device D, will be described.

[0131] The vapor chamber 1 obtained as described above is installed in a housing H of a mobile terminal or the like. An electronic device D, such as a CPU, which is a device to be cooled, is attached to the second upper sheet surface 20b of the upper sheet 20. The working fluid 2b in the sealed space 3 adheres to the wall surfaces of the sealed space 3 due to its surface tension. More specifically, the working fluid 2b adheres to the wall surfaces 53a of the lower vapor channel recess 53, the wall surfaces 54a of the upper vapor channel recess 54, the wall surfaces 62 of the liquid channel main grooves 61 of the liquid channel section 60, and the wall surfaces of the liquid channel connecting grooves 65. The working fluid 2b may also adhere to a portion of the second lower sheet surface 10b of the lower sheet 10 exposed to the lower vapor channel recess 53. The working fluid 2b may also adhere to a portion of the first upper sheet surface 20a of the upper sheet 20 exposed to the upper vapor channel recess 54, the liquid channel main grooves 61, and the liquid channel connecting grooves 65.

[0132] In this state, when the electronic device D generates heat, the working fluid 2b present in the evaporation region SR (see FIGS. 6 and 7) receives heat from the electronic device D. The received heat is absorbed as latent heat, and the working fluid 2b evaporates, generating working vapor 2a. Most of the generated working vapor 2a diffuses within the lower vapor flow path recess 53 and the upper vapor flow path recess 54 that form the sealed space 3 (see the solid arrows in FIG. 6). The working vapor 2a in each of the vapor flow path recesses 53 and 54 leaves the evaporation region SR. Most of the working vapor 2a is transported to the condensation region CR, which has a relatively low temperature. In FIGS. 6 and 7, most of the working vapor 2a is transported to the right portion of the vapor flow path section 50. In the condensation region CR, the working vapor 2a is cooled by radiating heat mainly 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 FIG. 3).

[0133] The working vapor 2a dissipates heat to the lower sheet 10 in the condensation region CR. As a result, the working vapor 2a loses the absorbed latent heat and condenses in the evaporation region SR, generating working fluid 2b. The generated working fluid 2b adheres to the wall surfaces 53a, 54a of the vapor flow path recesses 53, 54, the second lower sheet surface 10b of the lower sheet 10, and the first upper sheet surface 20a of the upper sheet 20. Here, the working fluid 2b continues to evaporate in the evaporation region SR. Therefore, the working fluid 2b in the region of the liquid flow path section 60 other than the evaporation region SR (i.e., the condensation region CR) is transported toward the evaporation region SR by the capillary action of each liquid flow path mainstream groove 61 (see the dashed arrows in FIG. 6). As a result, the working fluid 2b adhering to the wall surfaces 53a, 54a, the second lower sheet surface 10b, and the first upper sheet surface 20a moves to the liquid flow path section 60. At this time, the working fluid 2b passes through the liquid flow path connecting grooves 65 and enters the liquid flow path main grooves 61. In this way, the working fluid 2b is filled into each liquid flow path main groove 61 and each liquid flow path connecting groove 65. Therefore, the filled working fluid 2b obtains a driving force toward the evaporation region SR due to the capillary action of each liquid flow path main groove 61. In this way, the working fluid 2b is transported smoothly toward the evaporation region SR.

[0134] In the liquid flow path section 60, each liquid flow path mainstream groove 61 communicates with the adjacent other liquid flow path mainstream groove 61 via the corresponding liquid flow path connection groove 65. This allows the working fluid 2b to flow back and forth between the adjacent liquid flow path mainstream grooves 61, preventing dryout in the liquid flow path mainstream grooves 61. As a result, capillary action is imparted to the working fluid 2b in each liquid flow path mainstream groove 61, and the working fluid 2b is transported smoothly toward the evaporation region SR.

[0135] Note that a portion of the working fluid 2b condensed in the condensation region CR is transported not to the liquid flow path portion 60 but to the liquid storage portion 70 provided on the first main body surface 31a of the wick sheet 30. More specifically, a portion of the working fluid 2b adhering to each wall surface 53a, 54a, the second lower sheet surface 10b, and the first upper sheet surface 20a passes through the liquid storage communication grooves 75 and enters the liquid storage main grooves 71. In this way, the working fluid 2b is filled into each liquid storage main groove 71 and each liquid storage communication groove 75. Therefore, the working fluid 2b obtains a driving force due to the capillary action of each liquid storage main groove 71 and each liquid storage communication groove 75, and moves smoothly toward the inside of the liquid storage portion 70.

[0136] The working fluid 2b reaches the evaporation region SR via the liquid flow path section 60 and evaporates again upon receiving heat from the electronic device D. The working vapor 2a evaporated from the working fluid 2b passes through the liquid flow path communication groove 65 in the evaporation region SR and moves to the lower vapor flow path recess 53 and the upper vapor flow path recess 54, which have larger flow path cross-sectional areas. The working vapor 2a then diffuses within each of the vapor flow path recesses 53 and 54. Meanwhile, the liquid storage section 70 is disposed in the evaporation region SR. As a result, the working fluid 2b in the liquid storage section 70 similarly evaporates and diffuses within each of the vapor flow path recesses 53 and 54. 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. This transports and releases heat from the electronic device D. As a result, the electronic device D is cooled.

[0137] While the electronic device D stops generating heat, the working fluid 2b in the evaporation region SR does not evaporate but fills and remains in the liquid flow path mainstream groove 61 and the liquid flow path connecting groove 65 of the liquid flow path section 60. Therefore, the working fluid 2b in the condensation region CR remains there without being transported toward the evaporation region SR. A portion of the working fluid 2b in the liquid flow path section 60 flows along the wall surface 53a of the lower vapor flow path recess 53 or the wall surface 54a of the upper vapor flow path recess 54 and moves to the liquid storage mainstream groove 71 and the liquid storage connecting groove 75 of the liquid storage section 70. As a result, the working fluid 2b fills and remains in these grooves 71, 75. If the amount of working fluid 2b sealed in the sealed space 3 is greater than the total volume of the space defined by the liquid flow path mainstream groove 61 and the liquid flow path connecting groove 65, a portion of the working fluid 2b is likely to fill the liquid storage mainstream groove 71 and the liquid storage connecting groove 75. Therefore, the working fluid 2b can be dispersed and remain not only in the liquid flow path section 60 but also in the liquid storage section 70.

[0138] In this state, even if the electronic device E equipped with the vapor chamber 1 is placed in a temperature environment lower than the freezing point of the working fluids 2a and 2b, causing the working fluid 2b in the liquid flow path portion 60 to freeze and expand, the expansion force of the working fluids 2a and 2b is weakened. This reduces deformation of the upper sheet 20 due to the expansion force. This reduces the flatness of the second upper sheet surface 20b of the upper sheet 20 to which the electronic device D is attached, and prevents a gap from forming between the second upper sheet surface 20b and the electronic device D. This reduces the inhibition of heat conduction from the electronic device D, thereby preventing a decrease in performance of the vapor chamber 1. Similarly, even if the working fluid 2b in the liquid storage portion 70 freezes and expands, the expansion force is weakened. This reduces deformation of the lower sheet 10 due to the expansion force. This reduces the flatness of the first lower sheet surface 10a of the lower sheet 10.

[0139] As described above, according to the present embodiment, the liquid flow path portion 60 is provided on the second main body surface 31b of the sheet main body 31 of the wick sheet 30, and the liquid storage portion 70 is provided on the first main body surface 31a located opposite the second main body surface 31b. The flow path cross-sectional area of ​​the liquid storage mainstream groove 71 of the liquid storage portion 70 is larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61 of the liquid flow path portion 60. As a result, while the electronic device D is not generating heat, the working fluid 2b can be stored not only in the liquid flow path portion 60 but also dispersedly in the liquid storage portion 70. Therefore, even if the working fluid 2b in the liquid flow path portion 60 freezes and expands in a temperature environment below the freezing point of the working fluid 2b, the expansion force acting on the upper sheet 20 can be reduced. In this case, deformation of the upper sheet 20 can be suppressed. Furthermore, even if the working fluid 2b in the liquid storage portion 70 freezes and expands, the expansion force acting on the lower sheet 10 can be reduced. In this case, deformation of the lower sheet 10 can be suppressed. As a result, it is possible to suppress deformation of the vapor chamber 1 and to suppress deterioration of the performance of the vapor chamber 1. Furthermore, while the electronic device D is generating heat, the working fluid 2b in the liquid storage portion 70 can evaporate by receiving heat from the electronic device D. This allows the heat of the electronic device D to be further diffused, and the cooling efficiency of the electronic device D can be improved.

[0140] Furthermore, according to this embodiment, the liquid flow path portion 60 is provided on the second main body surface 31b of the sheet body 31 of the wick sheet 30, and the liquid storage portion 70 is provided on the first main body surface 31a located opposite the second main body surface 31b. The flow path cross-sectional area of ​​the liquid storage mainstream groove 71 of the liquid storage portion 70 is larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61 of the liquid flow path portion 60. This makes it possible to make the capillary force acting on the working fluid 2b in the liquid storage mainstream groove 71 smaller than the capillary force acting on the working fluid 2b in the liquid flow path mainstream groove 61. This reduces the amount of working fluid 2b moving to the liquid storage portion 70 while the electronic device D is generating heat. This prevents a decrease in the transport function of the working fluid 2b to the evaporation region SR, thereby preventing a decrease in heat transport efficiency. Furthermore, as described above, by making the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61, the total volume of the space formed by each liquid storage mainstream groove 71 can be increased. Therefore, while the electronic device D stops generating heat, the amount of hydraulic fluid 2b stored in the fluid reservoir 70 can be increased.

[0141] Furthermore, according to this embodiment, the width of the liquid storage mainstream groove 71 is larger than the width of the liquid flow path mainstream groove 61. This allows the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 to be larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61. This makes it possible to suppress a decrease in heat transport efficiency and increase the amount of working fluid 2b stored.

[0142] Furthermore, according to this embodiment, the depth of the liquid storage mainstream groove 71 is greater than the depth of the liquid flow path mainstream groove 61. This allows the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 to be greater than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61. This makes it possible to suppress a decrease in heat transport efficiency and increase the amount of working fluid 2b stored.

[0143] Furthermore, according to this embodiment, each land portion 33 is provided with a liquid flow path portion 60 and a liquid storage portion 70, and the number of liquid storage mainstream grooves 71 provided in a land portion 33 is smaller than the number of liquid flow path mainstream grooves 61 provided in the land portion 33. This allows the flow path cross-sectional area of ​​the liquid storage mainstream groove 71 to be larger than the flow path cross-sectional area of ​​the liquid flow path mainstream groove 61. This makes it possible to suppress a decrease in heat transport efficiency and increase the storage amount of working fluid 2b.

[0144] Furthermore, according to this embodiment, a liquid flow path portion 60 through which the working fluid 2b passes is provided on the second main body surface 31b of the sheet main body 31 of the wick sheet 30, and a liquid storage portion 70 is provided on the first main body surface 31a located opposite the second main body surface 31b. The liquid storage portion 70 is disposed in the evaporation region SR in a plan view. As a result, while the electronic device D is not generating heat, the working fluid 2b can be stored not only in the liquid flow path portion 60 but also dispersedly in the liquid storage portion 70. Therefore, even if the working fluid 2b in the liquid flow path portion 60 freezes and expands in a temperature environment below the freezing point of the working fluid 2b, the expansion force acting on the upper sheet 20 can be reduced. In this case, deformation of the upper sheet 20 can be suppressed. Furthermore, even if the working fluid 2b in the liquid storage portion 70 freezes and expands, the expansion force acting on the lower sheet 10 can be reduced. In this case, deformation of the lower sheet 10 can be suppressed. As a result, deformation of the vapor chamber 1 can be suppressed, and performance degradation of the vapor chamber 1 can be suppressed. Furthermore, while the electronic device D is generating heat, the working liquid 2b in the liquid storage portion 70 can evaporate by receiving heat from the electronic device D. This allows the heat of the electronic device D to be further diffused, improving the cooling efficiency of the electronic device D.

[0145] Furthermore, according to this embodiment, the liquid storage unit 70 is provided with a plurality of protrusions 74 that protrude from the sheet body 31 of the wick sheet 30 and contact the lower sheet 10. The gap between a pair of adjacent protrusions 74 (corresponding to the width w6 of the liquid storage mainstream groove 71) is larger than the width of the liquid flow path mainstream groove 61 of the liquid flow path unit 60. This allows the capillary force acting on the working fluid 2b in the liquid storage unit 70 to be smaller than the capillary force acting on the working fluid 2b in the liquid flow path unit 60 (in the liquid flow path mainstream groove 61). This reduces the amount of working fluid 2b moving to the liquid storage unit 70 while the electronic device D is generating heat. This prevents a decrease in the transport function of the working fluid 2b to the evaporation region SR, thereby preventing a decrease in heat transport efficiency. Furthermore, as described above, by making the gap between the protrusions 74 larger than the width of the liquid flow path mainstream groove 61, the total volume of the space formed by each liquid storage mainstream groove 71 and each liquid storage communication groove 75 in the liquid storage unit 70 can be increased. Therefore, while the electronic device D stops generating heat, the amount of hydraulic fluid 2b stored in the fluid reservoir 70 can be increased.

[0146] Furthermore, according to this embodiment, the liquid reservoir 70 has liquid storage mainstream grooves 71 provided between adjacent convex portions 74 in the Y direction, which is perpendicular to the X direction in which the liquid flow path mainstream grooves 61 of the liquid flow path section 60 extend. The liquid storage mainstream grooves 71 extend in the X direction. After the electronic device D stops generating heat, the working fluid 2b flows generally in the X direction from the condensation region CR toward the evaporation region SR. However, the working fluid 2b that reaches the liquid reservoir 70 can easily enter the liquid storage mainstream grooves 71. The working fluid 2b can then flow smoothly in the X direction within the liquid storage mainstream grooves 71 and easily reach the edge of the liquid reservoir 70 on the evaporation region SR side. This allows the working fluid 2b to be quickly drawn into the liquid reservoir 70, and the amount of working fluid 2b stored therein can be quickly increased. If the ambient temperature of the vapor chamber 1 suddenly drops, the working fluid 2b can be quickly drawn into the liquid reservoir 70. This effectively reduces the expansion force acting on the upper sheet 20 and the lower sheet 10 when the working fluid 2b freezes, thereby effectively suppressing deformation of the vapor chamber 1.

[0147] Furthermore, according to this embodiment, the gap between a pair of adjacent protrusions 74 is smaller than the gap between a pair of adjacent lands 33 (corresponding to the width w2 of the through-hole 34). This allows capillary force to act on the working liquid 2b in the liquid storage portion 70. Therefore, the working liquid 2b can be drawn into the liquid storage portion 70, and the working liquid 2b can be stored while the electronic device D is not generating heat.

[0148] Furthermore, according to this embodiment, the liquid storage section 70 is provided on the first main body surface 31a of each land section 33. This allows the hydraulic fluid 2b to be stored in a dispersed manner in each liquid storage section 70. Therefore, even if the hydraulic fluid 2b in the liquid flow path section 60 freezes and expands in a temperature environment lower than the freezing point of the hydraulic fluid 2b, deformation of the upper sheet 20 can be further suppressed. Furthermore, even if the hydraulic fluid 2b in the liquid storage section 70 freezes and expands, deformation of the lower sheet 10 can be further suppressed.

[0149] Furthermore, according to this embodiment, the liquid reservoir 70 is disposed on one side of the land portion 33 in the X direction. As a result, when the evaporation region SR is formed on one side of the vapor chamber 1 in the X direction, the liquid reservoir 70 can be disposed in the evaporation region SR. Therefore, while the electronic device D is generating heat, the working liquid 2b in the liquid reservoir 70 can evaporate, further dissipating the heat of the electronic device D. As a result, the cooling efficiency of the electronic device D can be improved.

[0150] (First Modification) In the above-described embodiment, an example has been described in which a portion of the working fluid 2b in the liquid flow path portion 60 moves to and is stored in the liquid storage portion 70 while the electronic device D stops generating heat. In this example, the working fluid 2b flows along the wall surface 53a of the lower vapor flow path recess 53 or the wall surface 54a of the upper vapor flow path recess 54. However, this is not limited to this, and the sheet main body 31 may be provided with a plurality of communication portions 80 that communicate between the liquid flow path portion 60 and the liquid storage portion 70. The communication portions 80 may be located within the evaporation region SR. Furthermore, the communication portions 80 may be located within a region that overlaps with the electronic device D in a planar view.

[0151] 15 and 16, the communication section 80 may include a communication recess 81 provided in the wall surface of the vapor flow path section 50. The communication recess 81 may extend from the liquid flow path section 60 to the liquid storage section 70. In the first modification shown in FIGS. 15 and 16, the communication recess 81 extending in the Z direction is provided along the wall surface 53a of the lower vapor flow path recess 53 and the wall surface 54a of the upper vapor flow path recess 54.

[0152] The communicating recess 81 may extend to at least one of the liquid flow path communication groove 65 of the liquid flow path section 60 and the liquid storage communication groove 75 of the liquid storage section 70. In a first modified example shown in FIGS. 15 and 16 , one end of the communicating recess 81 extends to the liquid flow path communication groove 65, and the other end of the communicating recess 81 extends to the liquid storage communication groove 75. The communicating recess 81 does not have to communicate with the liquid flow path communication groove 65, or the liquid storage communication groove 75. Furthermore, the communicating recess 81 does not have to communicate with either the liquid flow path communication groove 65 or the liquid storage communication groove 75. The cross-sectional shape of the communicating recess 81 may be rectangular as shown in FIGS. 15 and 16 , or may be formed into a curved shape such as a semicircular or semi-elliptical shape. The cross-sectional shape of the communicating recess 81 corresponds to the shape in a plan view.

[0153] As shown in FIG. 15, the width w9 of the communicating recess 81 may be larger than the width w4 of the liquid flow path communication groove 65 (see FIG. 9). The width w9 corresponds to the dimension in the X direction. This allows the capillary force acting on the working fluid 2b in the communicating recess 81 to be smaller than the capillary force acting on the working fluid 2b in the liquid flow path communication groove 65. In this case, it is possible to prevent the working fluid 2b from accumulating in the communicating recess 81. In this case, the communicating recess 81 is formed so as to cut out the protrusion 64. The width w9 of the communicating recess 81 may be smaller than the width w7 of the liquid storage communication groove 75 (see FIG. 10). This allows the capillary force to act on the working fluid 2b in the communicating recess 81, allowing the working fluid 2b to move to the liquid storage section 70. The width w9 of the communicating recess 81 may be, for example, 20 μm to 300 μm. The width w9 of the communication recess 81 means the dimension of the wick sheet 30 at the second main body surface 31b.

[0154] As described above, according to the first modification, while the electronic device D is not generating heat, a portion of the working fluid 2b in the liquid flow path section 60 can move to the liquid storage section 70 through the communication section 80. This increases the amount of working fluid 2b moving from the liquid flow path section 60 to the liquid storage section 70, and the amount of working fluid 2b stored in the liquid storage section 70 can be increased.

[0155] Furthermore, according to the first modified example, the communication section 80 includes a communication recess 81 provided in the wall surface of the vapor channel section 50, extending from the liquid channel section 60 to the liquid storage section 70. This reduces the flow resistance of the working fluid 2b from the liquid channel section 60 to the liquid storage section 70. This reduces the amount of working fluid 2b remaining in the liquid channel section 60. Even if the working fluid 2b in the liquid channel section 60 freezes and expands, the expansion force can be reduced. Furthermore, even if the working fluid 2b in the liquid storage section 70 freezes and expands, the expansion force can be reduced. As a result, deformation of the upper sheet 20 and the lower sheet 10 due to the force caused by the expansion can be suppressed. Furthermore, according to the first modified example, the communication recess 81 extends to the liquid channel communication groove 65 and the liquid storage communication groove 75, which further reduces the flow resistance of the working fluid 2b from the liquid channel section 60 to the liquid storage section 70.

[0156] (Second Modification) Unlike the first modified example shown in FIGS. 15 and 16 , the communication section 80 may include a through-hole 82 penetrating the sheet main body 31 and extending from the liquid flow path section 60 to the liquid storage section 70, as in a second modified example shown in FIGS. 17 and 18 . In the second modified example shown in FIGS. 17 and 18 , the through-hole 82 is located inside the land section 33 in a plan view, rather than on the wall surface 53 a of the lower steam flow path recess 53 or the wall surface 54 a of the upper steam flow path recess 54. The through-hole 82 is formed in a position where it is not cut out by the wall surface 53 a of the lower steam flow path recess 53 or the wall surface 54 a of the upper steam flow path recess 54. That is, the through-hole 82 has a closed contour in a plan view. FIGS. 17 and 18 show an example in which the through-hole 82 is rectangular. However, the planar shape of the through-hole 82 may be any shape, such as a circle.

[0157] The through-hole 82 may extend to at least one of the liquid flow path intersection 66 of the liquid flow path section 60 and the liquid storage intersection 76 of the liquid storage section 70. In a second modified example shown in FIGS. 17 and 18 , one end of the through-hole 82 extends to the liquid flow path intersection 66 and is located at the liquid flow path intersection 66. The other end of the through-hole 82 extends to the liquid storage intersection 76. Note that the through-hole 82 does not have to be connected to the liquid flow path intersection 66 as long as it is connected to the liquid flow path mainstream groove 61 or the liquid flow path communication groove 65. Alternatively, the through-hole 82 does not have to be connected to the liquid storage intersection 76 as long as it is connected to the liquid storage mainstream groove 71 or the liquid storage communication groove 75. The flow path cross-sectional shape of the through-hole 82 may be rectangular as shown in FIGS. 17 and 18 , or may be formed in a curved shape such as a circle or an ellipse. The flow path cross-sectional shape of the through-hole 82 corresponds to the shape in a plan view.

[0158] As shown in FIG. 17, the width w10 of the through-hole 82 may be larger than the width w4 of the liquid flow path communication groove 65 (see FIG. 9). The width w10 corresponds to the dimension in the X direction. This allows the capillary force acting on the working fluid 2b in the through-hole 82 to be smaller than the capillary force acting on the working fluid 2b in the liquid flow path communication groove 65. In this case, it is possible to prevent the working fluid 2b from accumulating in the through-hole 82. In this case, the through-hole 82 is formed so as to cut out the protrusion 64. The width w10 of the through-hole 82 may be smaller than the width w7 of the liquid storage communication groove 75 (see FIG. 10). This allows the capillary force to act on the working fluid 2b in the through-hole 82, allowing the working fluid 2b to move to the liquid storage section 70. The width w10 of the through-hole 82 may be, for example, 10 μm to 100 μm. 18, an example is shown in which the through holes 82 are formed to extend beyond the liquid storage intersection portion 76 due to the relationship between the arrangement pitch of the liquid flow path mainstream grooves 61 in the Y direction and the arrangement pitch of the liquid storage mainstream grooves 71 in the Y direction. However, this is not limiting, and the through holes 82 may not extend beyond the liquid storage intersection portion 76, depending on the arrangement pitch of these grooves 61, 71.

[0159] As described above, according to the second modification, while the electronic device D is not generating heat, a portion of the working fluid 2b in the liquid flow path 60 can move through the through-holes 82 to the liquid storage portion 70. This increases the amount of working fluid 2b moving from the liquid flow path 60 to the liquid storage portion 70, thereby increasing the amount of working fluid 2b stored in the liquid storage portion 70. In particular, because the through-holes 82 are located inside the land portions 33 in a plan view, the flow resistance of the working fluid 2b from the liquid flow path 60 to the liquid storage portion 70 can be reduced. This reduces the amount of working fluid 2b remaining in the liquid flow path 60. Even if the working fluid 2b in the liquid flow path 60 freezes and expands, the expansion force can be weakened. As a result, deformation of the upper sheet 20 due to the force caused by the expansion can be suppressed. Furthermore, even if the working fluid 2b in the liquid storage portion 70 freezes and expands, the expansion force can be weakened. As a result, deformation of the lower sheet 10 due to the force caused by the expansion can be suppressed.

[0160] Moreover, according to the second modified example, the communication portion 80 includes a through-hole 82 that penetrates the sheet main body 31 and extends from the liquid flow path portion 60 to the liquid storage portion 70. This further reduces the flow path resistance of the working fluid 2b from the liquid flow path portion 60 to the liquid storage portion 70. Therefore, the amount of working fluid 2b remaining in the liquid flow path portion 60 can be further reduced. Even if the working fluid 2b in the liquid flow path portion 60 freezes and expands, the expansion force can be further weakened. Furthermore, according to the second modified example, the through-hole 82 extends to the liquid flow path intersection portion 66 and the liquid storage intersection portion 76, so that the flow path resistance of the working fluid 2b from the liquid flow path portion 60 to the liquid storage portion 70 can be further reduced.

[0161] (Third Modification) In the above-described embodiment, the protrusions 74 provided in the liquid storage unit 70 are formed in a rectangular shape with the X direction as the longitudinal direction in a plan view. However, this is not limiting, and the planar shape of the protrusions 74 is arbitrary.

[0162] For example, as shown in Fig. 19, the protrusions 74 may be formed in a circular shape in a plan view, or may be formed in an elliptical shape (not shown). In the example shown in Fig. 19, the protrusions 74 are arranged in parallel. More specifically, the protrusions 74 of the protrusion rows 73 adjacent to each other in the Y direction are also aligned in the X direction.

[0163] Furthermore, for example, the protrusions 74 may be formed in a square shape in a plan view as shown in Fig. 20. In the example shown in Fig. 20, the protrusions 74 are arranged in a staggered pattern, but they may also be arranged in parallel.

[0164] Furthermore, for example, as shown in Fig. 21, the convex portions 74 may be formed in a cross shape in a plan view. In the example shown in Fig. 21, the planar shape of the convex portions 74 is formed in a rounded cross shape. In addition, although the example shown in Fig. 21 shows an example in which the convex portions 74 are arranged in a staggered pattern, they may also be arranged in parallel. Furthermore, the convex portions 74 may be formed in a star-shaped polygonal shape in a plan view.

[0165] (Fourth Modification) In the above-described embodiment, an example has been described in which the liquid reservoir 70 is provided on the first main body surface 31a of each land portion 33 of the wick sheet 30. However, this is not limited to this, and the liquid reservoir 70 does not have to be provided on all land portions 33. For example, the liquid reservoir 70 may be provided on only one arbitrary land portion 33, or on several land portions 33. For example, if the planar shape of the electronic device D is small, the liquid reservoir 70 may be selectively provided on an arbitrary land portion 33 depending on the area covered by the electronic device D. The same applies to cases in which the vapor chamber 1 is not simply rectangular.

[0166] (Fifth Modification) 22, the liquid storage section 70 may be disposed in a region of the vapor chamber 1 that overlaps with the electronic device D in a plan view.

[0167] In the example shown in FIG. 22 , a liquid storage portion 70 is provided on some of the multiple lands 33. An electronic device D overlaps the multiple lands 33. The electronic device D is arranged across the multiple lands 33. Seven lands 33 are shown in FIG. 22 , and the electronic device D overlaps three of the lands 33. The electronic device D does not overlap the remaining four lands 33. The three lands 33 overlapping the electronic device D are referred to as overlapping lands 91 and 92, and of the four lands 33 not overlapping the electronic device D, the land 33 adjacent to the overlapping lands 91 and 92 is referred to as a first non-overlapping land 93. Of the four lands 33 not overlapping the electronic device D, the land 33 not adjacent to the overlapping lands 91 and 92 is referred to as a second non-overlapping land 94.

[0168] The first non-polymerized land portions 93 are arranged on both sides of the three polymerized lands 91, 92 in the Y direction. The second non-polymerized land portion 94 is arranged on the opposite side of the first non-polymerized land portion 93 from the polymerized lands 91, 92. The second non-polymerized lands 94 are arranged at the bottom and top in FIG. 22, and two first non-polymerized lands 93 are arranged between these two second non-polymerized lands 94. The three polymerized lands 91, 92 are arranged between the two first non-polymerized lands 93. In FIG. 22, the lowest polymerized land portion of the three polymerized lands 91, 92 (the second polymerized land portion 92 described below) and the lower first non-polymerized land portion 93 are adjacent to each other in the Y direction. Similarly, in FIG. 22, the uppermost overlapping land of the three overlapping lands 91, 92 (a second overlapping land 92 described later) and the upper first non-overlapping land 93 are adjacent to each other in the Y direction.

[0169] A liquid reservoir 70 is provided on each of the polymerized lands 91, 92. The liquid reservoirs 70 provided on the polymerized lands 91, 92 are arranged in areas that overlap with the electronic device D in a plan view. These liquid reservoirs 70 may extend outward beyond the electronic device D in the X direction. The liquid reservoirs 70 provided on the polymerized lands 91, 92 extend outward beyond the electronic device D on both sides in the X direction. In the example shown in FIG. 22 , the liquid reservoirs 70 provided on the polymerized lands 91, 92 extend outward beyond the electronic device D to the left and right.

[0170] The three polymerized lands 91, 92 include one first polymerized land 91 and two second polymerized lands 92. The second polymerized lands 92 are arranged on both sides of the first polymerized land 91 in the Y direction. The second polymerized lands 92 are adjacent to the first polymerized land 91 in the Y direction. The liquid storage section 70 provided in the first polymerized land 91 and the liquid storage section 70 provided in the second polymerized land 92 are adjacent to each other in the Y direction. The liquid storage section 70 provided in the first polymerized land 91 is located closer to the center of the electronic device D in the Y direction than the liquid storage section 70 provided in the second polymerized land 92 in a plan view. In other words, the liquid storage section 70 provided in the second polymerized land 92 is farther from the center of the electronic device D than the liquid storage section 70 provided in the first polymerized land 91. 22, the liquid storage section 70 provided in the first polymer land section 91 overlaps the center of the electronic device D. The length L1 in the X direction of the liquid storage section 70 provided in the first polymer land section 91 is longer than the length L2 in the X direction of the liquid storage section 70 provided in the second polymer land section 92. The liquid storage section 70 provided in the first polymer land section 91 protrudes outward from the electronic device D by a greater amount than the liquid storage section 70 provided in the second polymer land section 92. The lengths L1 and L2 may be the lengths in the X direction of the liquid storage mainstream grooves 71 of the liquid storage section 70. If the liquid storage section 70 includes multiple liquid storage mainstream grooves 71, the lengths L1 and L2 may be the maximum lengths of the liquid storage mainstream grooves 71.

[0171] A liquid reservoir 70 is provided in each of the first non-polymerization lands 93. The liquid reservoir 70 provided in the first non-polymerization lands 93 is disposed in a region different from the region overlapping with the electronic device D in a planar view. That is, the liquid reservoir 70 does not overlap with the electronic device D. The liquid reservoir 70 provided in the second polymerization land 92 and the liquid reservoir 70 provided in the first non-polymerization land 93 are adjacent to each other in the Y direction. The length L2 in the X direction of the liquid reservoir 70 provided in the second polymerization land 92 is longer than the length L3 in the X direction of the liquid reservoir 70 provided in the first non-polymerization land 93. Note that FIG. 22 shows an example in which the length L3 is equal to that of the electronic device D. However, this is not a limitation, and the liquid reservoir 70 may extend outward beyond the electronic device D in the X direction. Alternatively, the length of the liquid reservoir 70 in the X direction may be shorter than the length of the electronic device D in the X direction. The length L3 may be the length of the liquid storage main groove 71 of the liquid storage portion 70 in the X direction, similar to the lengths L1 and L2.

[0172] 22, the second non-polymerized land portion 94 does not necessarily have to be provided with the liquid storage portion 70. However, this is not limitative, and the second non-polymerized land portion 94 may also have the liquid storage portion 70.

[0173] As described above, according to the fifth modification, the liquid storage unit 70 is disposed in an area of ​​the vapor chamber 1 that overlaps with the electronic device D in a plan view. This allows the liquid storage unit 70 to be disposed in an area that is likely to receive heat from the electronic device D. Therefore, while the electronic device D is generating heat, the working liquid 2b in the liquid storage unit 70 can evaporate by receiving heat from the electronic device D. This allows the heat of the electronic device D to be further diffused, improving the cooling efficiency of the electronic device D.

[0174] Furthermore, according to the fifth modification, the liquid reservoir 70 protrudes outward in the X direction beyond the electronic device D. This allows the working liquid 2b in the liquid reservoir 70 to evaporate around the area overlapping with the electronic device D by utilizing heat transferred from the electronic device D. More specifically, in the area adjacent in the X direction to the area overlapping with the electronic device D, the working liquid 2b in the liquid reservoir 70 can evaporate by utilizing heat from the electronic device D. This increases the amount of evaporation of the working liquid 2b. As a result, the heat from the electronic device D can be further diffused, and the cooling efficiency of the electronic device D can be further improved.

[0175] Furthermore, according to the fifth modification, the liquid storage section 70 provided in the first overlap land section 91 is located closer to the center of the electronic device D in the Y direction in a plan view than the liquid storage section 70 provided in the second overlap land section 92. The length L1 in the X direction of the liquid storage section 70 provided in the first overlap land section 91 is longer than the length L2 in the X direction of the liquid storage section 70 provided in the second overlap land section 92. This allows the length in the X direction of the liquid storage section 70 located closer to the center of the electronic device D to be longer. This allows the amount of working fluid 2b filled in the liquid storage mainstream groove 71 that overlaps with the vicinity of the center of the electronic device D to be increased. As a result, the amount of evaporation of the working fluid 2b near the center of the electronic device D can be increased, allowing the vicinity of the center of the electronic device D to be cooled efficiently.

[0176] Furthermore, according to the fifth modification, a liquid reservoir 70 is provided in each of a pair of adjacent second overlapping lands 92 and first non-overlapping lands 93. The liquid reservoir 70 provided in the second overlapping land 92 is disposed in a region overlapping with the electronic device D, and the liquid reservoir 70 provided in the first non-overlapping land 93 is disposed in a region different from the region overlapping with the electronic device D. This allows the working liquid 2b in the liquid reservoir 70 to evaporate around the region overlapping with the electronic device D by utilizing heat transferred from the electronic device D. More specifically, in a region adjacent in the Y direction to the region overlapping with the electronic device D, the working liquid 2b in the liquid reservoir 70 can evaporate by utilizing heat from the electronic device D. This increases the amount of evaporation of the working liquid 2b. As a result, the heat of the electronic device D can be further diffused, and the cooling efficiency of the electronic device D can be further improved.

[0177] Furthermore, according to the fifth modification, the length L2 in the X direction of the liquid storage portion 70 provided in the second overlapping land portion 92 is longer than the length L3 in the X direction of the liquid storage portion 70 provided in the first non-overlapping land portion 93. This makes it possible to increase the length in the X direction of the liquid storage portion 70 that overlaps with the electronic device D. This allows for an increase in the amount of working liquid 2b filled in the liquid storage main groove 71 that overlaps with the electronic device D. As a result, the amount of evaporation of the working liquid 2b in the region overlapping with the electronic device D can be increased, allowing for efficient cooling of the electronic device D.

[0178] In the fifth modified example described above, the liquid storage section 70 provided in the second overlapping land section 92 entirely overlaps with the electronic device D in the Y direction. However, this is not limited to this, and the liquid storage section 70 provided in the second overlapping land section 92 may overlap with the electronic device D over a portion of the Y direction (see FIG. 23). In this case, the liquid storage section 70 does not overlap with the electronic device D over the remaining portion of the Y direction. Also, FIG. 22 shows an example in which the electronic device D protrudes outward in the Y direction from the liquid storage section 70 provided in the second overlapping land section 92. However, this is not limited to this, and the electronic device D may coincide with the edge of the second overlapping land section 92. In this case, the edge of the electronic device D overlaps with the edge of the wall surface 54a of the upper vapor flow path recess 54 on the second main body surface 31b.

[0179] In the fifth modified example described above, an example has been described in which the electronic device D overlaps the liquid storage portion 70 provided on three overlapping lands 91, 92. However, this is not a limitation, and the number of overlapping lands 91, 92 on which the liquid storage portion 70 overlapping the electronic device D is provided is arbitrary. Also, an example has been described in which two non-overlapping lands 93, 94 are provided on each side of the three overlapping lands 91, 92 in the Y direction. However, this is not a limitation, and the number of non-overlapping lands 93, 94 provided on each side of the three overlapping lands 91, 92 in the Y direction may be one, or three or more.

[0180] (Sixth Modification) 23, the vapor chamber 1 may be in thermal contact with a plurality of electronic devices D.

[0181] More specifically, as shown in Fig. 23, a plurality of electronic devices D are attached to the second main body surface 31b. Here, as an example, two electronic devices D1 and D2 are attached to the second main body surface 31b, but the number of electronic devices D may be three or more. The two electronic devices D are arranged in different regions in the X direction. The electronic device D on the left side in Fig. 23 is referred to as the first electronic device D1, and the electronic device D on the right side is referred to as the second electronic device D2.

[0182] The first body surface 31a may be provided with a plurality of liquid reservoirs 70 corresponding to the electronic devices D1 and D2, respectively. In this case, the liquid reservoirs 70 may be arranged in areas that overlap the corresponding electronic devices D1 and D2 in a plan view.

[0183] Some of the land portions 33 are provided with liquid reservoirs 70. Each of the electronic devices D1 and D2 overlaps with the land portions 33, similar to the example shown in FIG. 22 . The land portions 33 include three overlapping lands 91 and 92, two first non-overlapping lands 93, and two second non-overlapping lands 94, similar to the example shown in FIG. 22 . Each of the three overlapping lands 91 and 92 is provided with a liquid reservoir 70 that overlaps the first electronic device D1 and a liquid reservoir 70 that overlaps the second electronic device D2. Similarly to the example shown in FIG. 22 , the first non-overlapping land portion 93 is provided with a liquid reservoir 70 that overlaps the first electronic device D1. However, the first non-overlapping land portion 93 does not have a liquid reservoir 70 that overlaps the second electronic device D2. The second non-overlapping land portion 94 does not have a liquid reservoir 70.

[0184] The dimensions of the two electronic devices D1 and D2 in the X direction may be different from each other. In this case, the lengths of the two liquid storage sections 70 in the X direction may be different from each other. Note that FIG. 23 shows an example in which the lengths of the liquid storage sections 70 in the X direction are equal for each electronic device D. The liquid storage section 70 overlapping the first electronic device D1 will be described in more detail. The lengths L1 and L2 in the X direction of the liquid storage sections 70 provided in the overlapping lands 91 and 92 are equal to each other. The lengths L1 and L2 are also equal to the length L3 in the X direction of the liquid storage section 70 provided in the first non-overlapping land 93. However, this is not limited to this, and the lengths L1, L2, and L3 in the X direction of the liquid storage section 70 may be different for each land, as shown in FIG. 22. The same applies to the liquid storage section 70 overlapping the second electronic device D2.

[0185] As described above, according to the sixth modification, the vapor chamber 1 is in thermal contact with the electronic devices D1 and D2, and the first body surface 31a is provided with a plurality of liquid reservoirs 70 corresponding to the electronic devices D1 and D2. The liquid reservoirs 70 are arranged in areas that overlap the corresponding electronic devices D1 and D2 in a plan view of the vapor chamber 1. This allows each liquid reservoir 70 to be arranged in an area that is likely to receive heat from the corresponding electronic device D1 and D2. Therefore, while the electronic devices D1 and D2 are generating heat, the working liquid 2b in each liquid reservoir 70 can evaporate due to the heat from the electronic devices D1 and D2. This further dissipates the heat from the electronic devices D1 and D2, improving the cooling efficiency of the electronic devices D1 and D2.

[0186] Furthermore, according to the sixth modification, a plurality of liquid reservoirs 70 overlapping the corresponding electronic devices D1, D2 are provided on at least one of the plurality of lands 33. This allows the liquid reservoirs 70 to be provided in areas of the land 33 that overlap the corresponding electronic devices D1, D2. Therefore, each liquid reservoir 70 can be disposed in an area that is likely to receive heat from the corresponding electronic devices D1, D2.

[0187] In the sixth modification, the two electronic devices D1 and D2 do not necessarily generate heat at the same time. For example, if the first electronic device D1 generates heat and the second electronic device D2 stops generating heat, the working liquid 2b in the liquid reservoir 70 that overlaps the first electronic device D1 can evaporate due to the heat from the first electronic device D1. The working liquid 2b in the liquid reservoir 70 that overlaps the second electronic device D2 can continue to be stored.

[0188] In the sixth modified example described above, two liquid reservoirs 70 are provided on each of the three overlapping lands 91, 92. However, this is not a limitation, and the number of overlapping lands 91, 92 on which two liquid reservoirs 70 are provided is not limited to three and is arbitrary. For example, the number of overlapping lands 91, 92 may be one. For example, two liquid reservoirs 70 may be provided on the first overlapping land 91, and one liquid reservoir 70 may be provided on the second overlapping land 92. In this case, the first overlapping land 91 may be provided with a liquid reservoir 70 that overlaps the first electronic device D1 and a liquid reservoir 70 that overlaps the second electronic device D2. One of the second overlapping lands 92 may be provided with a liquid reservoir 70 that overlaps the first electronic device D1, but no liquid reservoir 70 that overlaps the second electronic device D2. A liquid reservoir 70 overlapping the second electronic device D2 may be provided on the other side of the second overlapping land 92, and no liquid reservoir 70 overlapping the first electronic device D1 may be provided. That is, the overlapping lands 91, 92 may be provided with at least one of a liquid reservoir 70 overlapping the first electronic device D1 and a liquid reservoir 70 overlapping the second electronic device D2.

[0189] In the sixth modified example described above, the first body surface 31a is provided with a plurality of liquid reservoirs 70 so as to overlap the corresponding electronic devices D1 and D2 in a plan view. However, this is not limiting. For example, if the first body surface 31a is provided with a liquid reservoir 70 that overlaps one of the two electronic devices D1 and D2, it is not necessary to provide a liquid reservoir 70 that overlaps the other electronic device. The same applies when the number of electronic devices D is three or more. That is, it is possible to provide a plurality of liquid reservoirs 70 on the first body surface 31a so as to overlap all of the electronic devices D. However, it is also possible that the first body surface 31a is provided with liquid reservoirs 70 that overlap some of the electronic devices D and not with liquid reservoirs 70 that overlap other electronic devices D.

[0190] (Second embodiment) Next, a wick sheet for a vapor chamber, a vapor chamber, and an electronic device according to a second embodiment of the present invention will be described with reference to FIGS.

[0191] The second embodiment shown in Figures 24 to 27 differs mainly in that the liquid storage section is arranged in a region different from the evaporation region in plan view, and other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 23. In Figures 24 to 27, the same parts as those of the first embodiment shown in Figures 1 to 23 are designated by the same reference numerals and detailed description thereof will be omitted.

[0192] In this embodiment, as shown in FIG. 24 , the liquid reservoir 70 according to this embodiment may be disposed on one side of the land portion 33 in the X direction. The liquid reservoir 70 may be formed on the one side of the center of the land portion 33 in the X direction. The liquid reservoir 70 may be disposed on the opposite side of the evaporation region SR, or may be disposed on the right side of the land portion 33 as shown in FIG. 24 . The liquid reservoir 70 is disposed in a region different from the evaporation region SR in a plan view. The liquid reservoir 70 is disposed in the condensation region CR. In this case, the liquid reservoir 70 is disposed in a region different from the region overlapping with the electronic device D. More specifically, as shown in FIGS. 24 and 25 , the liquid reservoir 70 is disposed on the part of the land portion 33 opposite the evaporation region SR in the X direction. The liquid storage mainstream groove 71 of the liquid reservoir 70 is continuously formed from the edge of the land portion 33 opposite the evaporation region SR in the X direction toward the edge on the evaporation region SR side to a predetermined position. 24, the liquid reservoir 70 is formed from the right edge toward the left edge to a predetermined position. In this way, the X-direction range of the liquid reservoir 70 is defined. The other configuration of the liquid reservoir 70 is similar to that of the liquid reservoir 70 in the first embodiment, so detailed description will be omitted here.

[0193] In a typical vapor chamber 1, as described above, the working fluids 2a and 2b circulate within the sealed space 3 while repeatedly undergoing phase changes, i.e., evaporation and condensation, to transport and release heat from the electronic device D. The circulation of the working fluids 2a and 2b can be formed throughout the entire vapor chamber 1. This allows the working vapor 2a to release heat throughout the entire vapor chamber 1, widening the heat release area. This improves the heat dissipation efficiency of the vapor chamber 1 and allows the electronic device D to be cooled efficiently. In this case, the temperature difference within the vapor chamber 1 can be reduced, and the temperature can be equalized.

[0194] However, when the heat generation amount of the electronic device D is large, as shown in FIG. 26, the working fluid 2b condensed in the condensation region CR is difficult to transport to the center of the evaporation region SR. In other words, because the heat generation amount of the electronic device D is large, the working fluid 2b is likely to evaporate before reaching the center of the evaporation region SR. As a result, a circulation flow of the working fluids 2a and 2b is formed in an area excluding the vicinity of the center of the evaporation region SR, and the temperature of the center of the evaporation region SR may rise. This may reduce the cooling efficiency of the electronic device D. As a result, a high-temperature region TH and a low-temperature region TL are formed in the vapor chamber 1, and the temperature difference may become large.

[0195] On the other hand, when the heat generation amount of the electronic device D is small, as shown in FIG. 27, a portion of the working fluid 2b condensed in the condensation region CR tends to accumulate in the liquid flow path section 60 of the evaporation region SR. That is, because the heat generation amount of the electronic device D is small, the amount of evaporation of the working fluid 2b in the evaporation region SR decreases. The transport amount of the working fluid 2b toward the evaporation region SR decreases, and the working fluid 2b tends to accumulate in the liquid flow path section 60 of the condensation region CR. As a result, the reflux of the working fluids 2a and 2b is formed in an area excluding the vicinity of the end on the evaporation region SR side (near the right end in FIG. 27), and the working fluid 2b near this end may accumulate in the liquid flow path section 60. This narrows the area from which the working vapor 2a releases heat, which may reduce the heat dissipation efficiency of the vapor chamber 1. As a result, a high-temperature region TH and a low-temperature region TL are formed in the vapor chamber 1, which may increase the temperature difference.

[0196] In contrast, in the vapor chamber 1 according to the present embodiment, while the electronic device D is generating heat, a portion of the working liquid 2b condensed in the condensation region CR is transported to the liquid reservoir 70 provided on the first main body surface 31a of the wick sheet 30, rather than to the evaporation region SR. The working liquid 2b is then stored in the liquid reservoir 70. Because the liquid reservoir 70 according to the present embodiment is disposed in the condensation region CR, the working liquid 2b in the liquid reservoir 70 is less likely to evaporate and is therefore stored in the liquid reservoir 70.

[0197] When the heat generation amount of the electronic device D is large, the working fluid 2b condensed in the condensation region CR can be transported to the center of the evaporation region SR. In other words, even when the heat generation amount of the electronic device D is large, not only the working fluid 2b in the liquid flow path section 60 but also the working fluid 2b stored in the liquid storage section 70 can be transported toward the center of the evaporation region SR, thereby increasing the amount of working fluid 2b transported to the evaporation region SR. This allows the working fluid 2b to reach the center of the evaporation region SR, and a circulation flow of the working fluids 2a and 2b can be formed throughout the entire vapor chamber 1. This reduces the temperature at the center of the evaporation region SR, improving the cooling efficiency of the electronic device D. As a result, the temperature difference in the vapor chamber 1 can be reduced, and the temperature can be equalized.

[0198] On the other hand, when the heat generation amount of the electronic device D is small, a portion of the working fluid 2b condensed in the condensation region CR can be stored in the liquid storage section 70, and the working fluid 2b can be prevented from accumulating in the liquid flow path section 60 of the evaporation region SR. This allows the circulation of the working fluids 2a, 2b to be formed throughout the entire vapor chamber 1. This increases the area from which the working vapor 2a releases heat, improving the heat dissipation efficiency of the vapor chamber 1. As a result, the temperature difference in the vapor chamber 1 can be reduced.

[0199] According to this embodiment, the second main body surface 31b of the sheet body 31 of the wick sheet 30 is provided with a liquid flow path 60 through which the working fluid 2b passes, and the liquid storage portion 70 is provided on the first main body surface 31a, which is located opposite the second main body surface 31b. The liquid storage portion 70 is located in a region different from the evaporation region SR in a plan view. This allows the working fluid 2b to be stored not only in the liquid flow path 60 but also in a dispersed manner in the liquid storage portion 70. When the electronic device D generates a large amount of heat, the working fluid 2b stored in the liquid storage portion 70 can be sent to the evaporation region SR, thereby increasing the range of circulation of the working fluids 2a and 2b. This improves the cooling efficiency of the electronic device D. Furthermore, when the electronic device D generates a small amount of heat, the working fluid 2b can be prevented from stagnation in the liquid flow path 60 of the evaporation region SR, thereby increasing the range of circulation of the working fluids 2a and 2b. This increases the area from which the working vapor 2a releases heat, thereby improving the heat dissipation efficiency of the vapor chamber 1. As a result, regardless of the amount of heat generated by the electronic device D, the performance degradation of the vapor chamber 1 can be suppressed.

[0200] Furthermore, according to this embodiment, as described above, the working fluid 2b can be stored in the liquid storage unit 70. As a result, while the electronic device D is not generating heat, the working fluid 2b can be stored not only in the liquid flow path unit 60 but also dispersedly in the liquid storage unit 70. Therefore, even if the working fluid 2b in the liquid flow path unit 60 freezes and expands in a temperature environment lower than the freezing point of the working fluid 2b, the expansion force acting on the upper sheet 20 can be reduced, and deformation of the upper sheet 20 can be suppressed. Furthermore, even if the working fluid 2b in the liquid storage unit 70 freezes and expands, the expansion force acting on the lower sheet 10 can be reduced, and deformation of the lower sheet 10 can be suppressed. As a result, deformation of the vapor chamber 1 can be suppressed.

[0201] Furthermore, according to this embodiment, the liquid storage unit 70 is provided with a plurality of protrusions 74 that protrude from the sheet body 31 of the wick sheet 30 and contact the lower sheet 10. The gap between a pair of adjacent protrusions 74 (corresponding to the width w6 of the liquid storage mainstream groove 71) is larger than the width w3 of the liquid flow path mainstream groove 61 of the liquid flow path unit 60. This makes it possible to reduce the capillary force acting on the working fluid 2b in the liquid storage unit 70 compared to the capillary force acting on the working fluid 2b in the liquid flow path unit 60 (in the liquid flow path mainstream groove 61). This reduces the amount of working fluid 2b moving to the liquid storage unit 70 while the electronic device D is generating heat. This prevents a decrease in the transport function of the working fluid 2b to the evaporation region SR, thereby preventing a decrease in heat transport efficiency. Furthermore, as described above, by making the gap between the protrusions 74 larger than the width w3 of the liquid flow path mainstream groove 61, the total volume of the space formed by each liquid storage mainstream groove 71 and each liquid storage communication groove 75 in the liquid storage unit 70 can be increased. This increases the amount of working fluid 2b stored in the liquid reservoir 70, and further prevents the working fluid 2b from accumulating in the liquid flow path 60 in the condensation region CR when the amount of heat generated by the electronic device D is small.

[0202] Furthermore, according to this embodiment, the liquid storage section 70 has liquid storage mainstream grooves 71 provided between adjacent convex portions 74 in the Y direction perpendicular to the X direction, which is the direction in which the liquid flow path mainstream grooves 61 of the liquid flow path section 60 extend, and the liquid storage mainstream grooves 71 extend in the X direction. This allows the working fluid 2b in the liquid storage section 70 to flow in the X direction, and the working fluid 2b flowing out of the liquid storage section 70 can have a propulsive force in the X direction. Therefore, the working fluid 2b flowing out of the liquid storage section 70 can be smoothly transported to the evaporation region SR.

[0203] Furthermore, according to this embodiment, the gap between a pair of adjacent protrusions 74 is smaller than the gap between a pair of adjacent lands 33 (corresponding to the width w2 of the through-hole 34). This allows capillary force to act on the working fluid 2b in the liquid storage portion 70. As a result, the working fluid 2b can be drawn into the liquid storage portion 70, and the working fluid 2b can be stored.

[0204] Furthermore, according to this embodiment, the liquid storage section 70 is provided on the first main body surface 31a of each land section 33. This allows the working fluid 2b to be stored in a dispersed manner in each liquid storage section 70. Therefore, when the amount of heat generated by the electronic device D is large, the amount of working fluid 2b sent to the evaporation region SR can be increased, further improving the cooling efficiency of the electronic device D. When the amount of heat generated by the electronic device D is small, the working fluid 2b can be further prevented from accumulating in the liquid flow path section 60, further improving the heat dissipation efficiency of the vapor chamber 1.

[0205] Furthermore, according to this embodiment, the liquid reservoir 70 is disposed on one side of the land portion 33 in the X direction. As a result, when the evaporation region SR is formed on one side of the vapor chamber 1 in the X direction, the liquid reservoir 70 can be disposed in a region different from the evaporation region SR. Therefore, when the amount of heat generated by the electronic device D is large, the amount of working liquid 2b sent to the evaporation region SR can be increased, further improving the cooling efficiency of the electronic device D. When the amount of heat generated by the electronic device D is small, the working liquid 2b can be further prevented from accumulating in the liquid flow path portion 60, further improving the heat dissipation efficiency of the vapor chamber 1.

[0206] In addition, in the present embodiment described above, similarly to the first embodiment, the first, second, third, and fourth modifications described as modifications of the first embodiment can be applied.

[0207] For example, in the second embodiment, by providing the communication section 80 as in the first modification, the working fluid 2b can move smoothly between the liquid flow path section 60 and the liquid storage section 70. This increases the amount of working fluid 2b moving from the liquid flow path section 60 to the liquid storage section 70, thereby increasing the amount of working fluid 2b stored in the liquid storage section 70. Furthermore, when the amount of heat generated by the electronic device D is large, the working fluid 2b stored in the liquid storage section 70 can be smoothly sent to the evaporation region SR. This effectively increases the range over which the working fluids 2a and 2b return. This further improves the cooling efficiency of the electronic device D. Furthermore, when the amount of heat generated by the electronic device D is small, this further prevents the working fluid 2b from accumulating in the liquid flow path section 60 of the evaporation region SR, thereby increasing the range over which the working fluids 2a and 2b return. This further improves the heat dissipation efficiency of the vapor chamber 1.

[0208] Furthermore, as in the first modified example, the communication portion 80 includes the communication recess 81, which reduces the flow path resistance of the working fluid 2b between the liquid flow path portion 60 and the liquid storage portion 70. This further improves the cooling efficiency of the electronic device D when the amount of heat generated by the electronic device D is large. Furthermore, the heat dissipation efficiency of the vapor chamber 1 further improves when the amount of heat generated by the electronic device D is small. Furthermore, according to the first modified example, the communication recess 81 extends to the liquid flow path communication groove 65 and the liquid storage communication groove 75, which further reduces the flow path resistance of the working fluid 2b between the liquid flow path portion 60 and the liquid storage portion 70.

[0209] For example, in the second embodiment, by including the through-hole 82 in the communication section 80 as in the second modification, the flow resistance of the working fluid 2b between the liquid flow section 60 and the liquid storage section 70 can be reduced. This can further improve the cooling efficiency of the electronic device D when the amount of heat generated by the electronic device D is large, and can further improve the heat dissipation efficiency of the vapor chamber 1 when the amount of heat generated by the electronic device D is small. Furthermore, according to the second modification, by extending the through-hole 82 to the liquid flow section intersection 66 and the liquid storage section 76, the flow resistance of the working fluid 2b between the liquid flow section 60 and the liquid storage section 70 can be further reduced.

[0210] Furthermore, the liquid reservoir 70 according to the present embodiment and the liquid reservoir 70 according to the first embodiment may be combined. In this case, two liquid reservoirs 70 are provided in each land portion 33 of the wick sheet 30. One liquid reservoir 70 is disposed in the evaporation region SR in a plan view, and the other liquid reservoir 70 is disposed in the condensation region CR in a plan view. The liquid reservoir 70 in the evaporation region SR and the liquid reservoir 70 in the condensation region CR may be spaced apart from each other in the X direction. In this case, it is possible to obtain both the effects obtained by the liquid reservoir 70 according to the first embodiment and the effects obtained by the liquid reservoir 70 according to the second embodiment.

[0211] The present invention is not limited to the above-described embodiments and modifications, and can be embodied by modifying the components within the scope of the gist of the present 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 the components shown in the embodiments and modifications.

Claims

1. A wick sheet for a vapor chamber, comprising: a seat body having a first body surface and a second body surface provided on the opposite side to the first body surface; a vapor flow path portion provided in the seat body and through which a gas of the working fluid passes; a first liquid flow path portion provided on the second main body surface, communicating with the vapor flow path portion and through which the liquid of the working fluid passes; a second liquid flow path portion provided on the first main body surface and communicating with the vapor flow path portion so that the liquid of the working fluid passes through; A wick sheet for a vapor chamber, wherein the capillary force acting on the liquid of the working fluid in the second liquid flow path portion is smaller than the capillary force acting on the liquid of the working fluid in the first liquid flow path portion.

2. The wick sheet for a vapor chamber according to claim 1 , wherein, in a plan view, an area in which the second liquid flow path portion is arranged is narrower than an area in which the first liquid flow path portion is arranged.

3. the seat body has a plurality of land portions that divide the steam flow path portion into a plurality of steam passages, The wick sheet for a vapor chamber according to claim 1 or 2, wherein the second liquid flow path portion is disposed on one side of the land portion in a direction in which the land portion extends.

4. the first liquid flow path portion includes a plurality of first main grooves, the second liquid flow path portion includes a plurality of second main grooves, 4. The wick sheet for a vapor chamber according to claim 1, wherein a flow path cross-sectional area of ​​the second main groove is larger than a flow path cross-sectional area of ​​the first main groove.

5. the first liquid flow path portion includes a plurality of first main grooves, the second liquid flow path portion includes a plurality of second main grooves, The wick sheet for a vapor chamber according to any one of claims 1 to 4, wherein a width of the second main groove is larger than a width of the first main groove.

6. the first liquid flow path portion includes a plurality of first main grooves, the second liquid flow path portion includes a plurality of second main grooves, The wick sheet for a vapor chamber according to any one of claims 1 to 5, wherein the depth of the second main groove is greater than the depth of the first main groove.

7. A wick sheet for a vapor chamber, comprising: a seat body having a first body surface and a second body surface provided on the opposite side to the first body surface; a vapor flow path portion provided in the seat body and through which a gas of the working fluid passes; a first capillary structure provided on the second body surface, communicating with the vapor flow path portion and through which the working fluid liquid passes; a second capillary structure provided on the first body surface, communicating with the vapor flow path portion and through which the liquid of the working fluid passes; A wick sheet for a vapor chamber, wherein the capillary force acting on the working fluid liquid in the second capillary structure is smaller than the capillary force acting on the working fluid liquid in the first capillary structure.

8. A wick sheet for a vapor chamber, comprising: a seat body having a first body surface and a second body surface provided on the opposite side to the first body surface; a vapor flow path portion provided in the seat body and through which a gas of the working fluid passes; a liquid flow path portion provided on the second main body surface and communicating with the vapor flow path portion through which the liquid of the working fluid passes; a liquid storage section provided on the first main body surface, communicating with the vapor flow path section and storing the liquid of the working fluid; A wick sheet for a vapor chamber, wherein, in a plan view, the area in which the liquid storage section is arranged is narrower than the area in which the liquid flow path section is arranged.

9. the seat body has a plurality of land portions that divide the steam flow path portion into a plurality of steam passages, The wick sheet for a vapor chamber according to claim 8 , wherein the liquid storage portion is disposed on one side of the land portion in the direction in which the land portion extends.

10. The first sheet, A second seat; A vapor chamber comprising: a wick sheet for a vapor chamber according to any one of claims 1 to 9, interposed between the first sheet and the second sheet.

11. Housing and an electronic device contained within the housing; An electronic device comprising: the vapor chamber of claim 10 in thermal contact with the electronic device.

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