Vapor chamber, electronic device, and metal sheet for vapor chamber

Abstract

To provide a vapor chamber which can improve a transport function for liquefied working fluid by securing a flow passage cross-sectional area of a liquid flow passage part and can improve heat transfer efficiency, an electronic apparatus, a metal sheet for the vapor chamber and a method for manufacturing the vapor chamber.SOLUTION: A liquid flow passage part of a vapor chamber according to the present invention includes a first main flow groove 31, a second main flow groove 32 and a third main flow groove 33. A first protrusion row including a plurality of first protrusions 41a arranged across first communication grooves 51 is provided between the first main flow groove 31 and the second main flow groove 32. A second protrusion row including a plurality of second protrusions 42a arranged across second communication grooves 52 is provided between the second main flow groove 32 and the third main flow groove 33. The second main flow groove 32 includes first intersection parts (P1) in which at least some of the first communication grooves (51) lie opposite the second protrusions (42a), and second intersection parts in which at least some of the second communication grooves (52) lie opposite the first protrusions (41a).SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a vapor chamber having a sealed space in which a working fluid is sealed, an electronic device, a metal sheet for a vapor chamber, and a method for manufacturing a vapor chamber.

Background Art

[0002] Devices that generate heat, such as a central processing unit (CPU), a light-emitting diode (LED), and a power semiconductor, which are used in mobile terminals such as mobile phones and tablet terminals, are cooled by heat dissipation members such as heat pipes (see, for example, Patent Documents 1 to 5). In recent years, due to the thinning of mobile terminals such as mobile phones, the thinning of heat dissipation members has also been demanded, and the development of a vapor chamber that can be made thinner than a heat pipe has been promoted. A working fluid is enclosed in the vapor chamber, and the working fluid absorbs the heat of the device and releases it to the outside, thereby cooling the device.

[0003] More specifically, the working fluid in the vapor chamber receives heat from the device at a portion (evaporation portion) close to the device and evaporates into vapor. Then, the vapor moves to a position away from the evaporation portion, is cooled, and condenses into a liquid state. In the vapor chamber, a liquid flow path portion as a capillary structure (wick) is provided, and the liquefied working fluid passes through this liquid flow path portion and is transported toward the evaporation portion, and again receives heat at the evaporation portion and evaporates. In this way, the working fluid refluxes in the vapor chamber while repeating a phase change, that is, evaporation and condensation, thereby transferring the heat of the device and increasing the heat dissipation efficiency.

[0004] By the way, the liquid flow path portion has a plurality of grooves extending in a first direction. The working fluid obtains a driving force toward the evaporation portion by capillary action and passes through the grooves toward the evaporation portion. In addition, in order to allow the working fluid to flow back and forth between adjacent grooves, other grooves extending in a second direction orthogonal to the first direction are provided. In this way, a plurality of grooves are formed in a lattice shape in the liquid flow path portion so that the working fluid is evenly distributed in the liquid flow path portion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when forming a plurality of grooves in a lattice pattern, problems may occur due to the pressure received from the outside air.

[0007] That is, the vapor chamber is composed of two metal sheets, and the above-described grooves are formed in at least one of the metal sheets. As a result, in the portion of the metal sheet where the grooves are formed, the thickness of the metal material is reduced. Since the space inside the liquid flow path portion is depressurized, the metal sheet receives pressure in the direction of concave inward from the outside air. For this reason, the metal sheet may be concave inward along the grooves. In particular, when attempting to thin the vapor chamber as described above, the thickness of the metal sheet becomes smaller, and it may be more likely to be concave.

[0008] At the intersection where the grooves orthogonal to each other intersect, when the metal sheet is recessed along the groove along the second direction, the recess can be formed so as to cross the groove along the first direction. In this case, the flow path cross-sectional area of the groove along the first direction becomes small, and the flow path resistance of the working fluid can increase. For this reason, the transport function of the liquid working fluid to the evaporation section can deteriorate, and the supply amount of the working fluid to the evaporation section can decrease. In this case, the amount of heat transported from the evaporation section decreases, and there arises a problem that the heat transport efficiency deteriorates.

[0009] The present invention has been made in consideration of such points, and an object thereof is to provide a vapor chamber, an electronic device, a metal sheet for a vapor chamber, and a method for manufacturing a vapor chamber that can secure the flow path cross-sectional area of the liquid flow path section, improve the transport function of the liquid working fluid, and improve the heat transport efficiency.

Means for Solving the Problems

[0010] The present invention is a vapor chamber in which a working fluid is enclosed, a first metal sheet, a second metal sheet provided on the first metal sheet, a sealed space provided between the first metal sheet and the second metal sheet, the sealed space having a vapor flow path section through which the vapor of the working fluid passes and a liquid flow path section through which the liquid working fluid passes, the liquid flow path section is provided on the surface of the first metal sheet on the side of the second metal sheet, the liquid flow path section has a first main flow groove, a second main flow groove, and a third main flow groove that each extend in a first direction and through which the liquid working fluid passes, the first main flow groove, the second main flow groove, and the third main flow groove are arranged in this order in a second direction orthogonal to the first direction, a first convex portion row including a plurality of first convex portions arranged in the first direction via a first connection groove is provided between the first main flow groove and the second main flow groove, a second convex portion row including a plurality of second convex portions arranged in the first direction via a second connection groove is provided between the second main flow groove and the third main flow groove, The first communication groove communicates the first main flow groove and the second main flow groove. The second communication groove communicates the second main flow groove and the third main flow groove. The second main flow groove includes a first intersection portion where at least a part of the first communication groove faces the second convex portion, and a second intersection portion where at least a part of the second communication groove faces the first convex portion, in a vapor chamber. is provided.

[0011] In the vapor chamber described above, the first intersection portion and the second intersection portion of the second main flow groove are adjacent to each other. It may be like this.

[0012] Also, in the vapor chamber described above, the second main flow groove includes a plurality of the first intersection portions and a plurality of the second intersection portions, and the first intersection portions and the second intersection portions of the second main flow groove are arranged alternately. It may be like this.

[0013] Also, in the vapor chamber described above, the liquid flow path portion further has a fourth main flow groove that extends in the first direction and through which the liquid working fluid passes, the fourth main flow groove is arranged on the side opposite to the side of the second main flow groove with respect to the third main flow groove, a third convex portion row including a plurality of third convex portions arranged in the first direction via a third communication groove is provided between the third main flow groove and the fourth main flow groove, the third communication groove communicates the third main flow groove and the fourth main flow groove, the third main flow groove includes a first intersection portion where at least a part of the second communication groove faces the third convex portion, and a second intersection portion where at least a part of the third communication groove faces the second convex portion. It may be like this.

[0014] Also, in the vapor chamber described above, The first intersection portion and the second intersection portion of the third main flow channel are adjacent to each other. This may be the case.

[0015] Also, in the vapor chamber described above, the third main flow channel includes a plurality of the first intersection portions and a plurality of the second intersection portions, and the first intersection portions and the second intersection portions of the third main flow channel are arranged alternately. This may be the case.

[0016] Also, in the vapor chamber described above, the second metal sheet has a flat contact surface that contacts the surface of the first metal sheet on the side of the second metal sheet and covers the second main flow channel. This may be the case.

[0017] Also, in the vapor chamber described above, the width of the second main flow channel may be larger than the width of the first convex portion and the width of the second convex portion. This may be the case.

[0018] Also, in the vapor chamber described above, the width of the first connection groove is larger than the width of the first main flow channel and the width of the second main flow channel, and the width of the second connection groove is larger than the width of the second main flow channel and the width of the third main flow channel. This may be the case.

[0019] Also, in the vapor chamber described above, the depth of the first connection groove is deeper than the depth of the first main flow channel and the depth of the second main flow channel, and the depth of the second connection groove is deeper than the depth of the second main flow channel and the depth of the third main flow channel. This may be the case.

[0020] Also, in the vapor chamber described above, The depth of the first intersection portion and the depth of the second intersection portion of the second main flow channel are deeper than the depth of the portion between the first convex portion and the second convex portion that are adjacent to each other in the second main flow channel. This may be the case.

[0021] Also, in the vapor chamber described above, The depth of the first intersection portion and the depth of the second intersection portion of the second main flow channel are deeper than the depth of the first connection groove and the depth of the second connection groove. This may be the case.

[0022] Also, in the vapor chamber described above, The first convex portion includes a pair of first convex portion end portions provided at both end portions in the first direction and a first convex portion intermediate portion provided between the pair of first convex portion end portions. The width of the first convex portion intermediate portion is smaller than the width of the first convex portion end portion. This may be the case.

[0023] Also, in the vapor chamber described above, A rounded curved portion is provided at the corner portion of the first convex portion. This may be the case.

[0024] Also, in the vapor chamber described above, The second metal sheet has a plurality of main flow channel convex portions that protrude from the surface of the second metal sheet on the side of the first metal sheet into the first main flow channel, the second main flow channel, and the third main flow channel of the first metal sheet, respectively. This may be the case.

[0025] Also, in the vapor chamber described above, The cross section of the main flow channel convex portion is formed in a curved shape. This may be the case.

[0026] Also, in the vapor chamber described above, The second metal sheet has a plurality of communication groove protrusions protruding from the surface of the second metal sheet on the side of the first metal sheet into the first communication groove and the second communication groove of the first metal sheet, respectively. It may be like this.

[0027] Also, in the vapor chamber described above, The cross section of the communication groove protrusion is formed in a curved shape. It may be like this.

[0028] Furthermore, the present invention A housing, A device housed in the housing, The vapor chamber described above that is in thermal contact with the device, and an electronic device comprising the same. is provided.

[0029] Furthermore, the present invention A metal sheet for a vapor chamber for a vapor chamber having a sealed space including a vapor flow path portion through which vapor of the working fluid passes and a liquid flow path portion through which the liquid working fluid passes, with the working fluid sealed therein, The first surface, A second surface provided on the side opposite to the first surface, and includes: The liquid flow path portion is provided on the first surface, The liquid flow path portion has a first main flow groove, a second main flow groove, and a third main flow groove each extending in a first direction through which the liquid working fluid passes, The first main flow groove, the second main flow groove, and the third main flow groove are arranged in this order in a second direction orthogonal to the first direction, A first convex portion row including a plurality of first convex portions arranged in the first direction via a first communication groove is provided between the first main flow groove and the second main flow groove, A second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove is provided between the second main flow groove and the third main flow groove, The first communication groove communicates the first main flow groove and the second main flow groove, The second communication groove communicates the second main flow groove and the third main flow groove. The second main flow groove includes a first intersection portion where at least a part of the first communication groove faces the second convex portion, and a second intersection portion where at least a part of the second communication groove faces the first convex portion, and is a metal sheet for a vapor chamber. to provide.

[0030] Also, the present invention is A sealed space provided between a first metal sheet and a second metal sheet and filled with a working fluid, the sealed space including a vapor flow path portion through which vapor of the working fluid passes and a liquid flow path portion through which the liquid working fluid passes, and a method for manufacturing a vapor chamber having the sealed space, A half-etching step of forming the liquid flow path portion on the surface of the first metal sheet on the side of the second metal sheet by half-etching, A joining step of joining the first metal sheet and the second metal sheet, the joining step of forming the sealed space between the first metal sheet and the second metal sheet, and a filling step of filling the working fluid into the sealed space. The liquid flow path portions each have a first main flow groove, a second main flow groove, and a third main flow groove that extend in a first direction and through which the liquid working fluid passes, The first main flow groove, the second main flow groove, and the third main flow groove are arranged in this order in a second direction orthogonal to the first direction, A first convex portion row including a plurality of first convex portions arranged in the first direction via a first communication groove is provided between the first main flow groove and the second main flow groove, A second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove is provided between the second main flow groove and the third main flow groove, The first communication groove communicates the first main flow groove and the second main flow groove, The second communication groove communicates the second main flow groove and the third main flow groove, The second main flow channel includes a first intersection part where at least a part of the first connection channel faces the second convex part, and a second intersection part where at least a part of the second connection channel faces the first convex part. A method for manufacturing a vapor chamber. is provided.

Advantages of the Invention

[0031] According to the present invention, it is possible to secure the flow path cross-sectional area of the liquid flow path part, improve the transport function of the liquid working fluid, and improve the heat transport efficiency.

Brief Description of the Drawings

[0032]

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Embodiments for Carrying Out the Invention

[0033] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0034] (First Embodiment) Using FIGS. 1 to 18, the vapor chamber, electronic device, metal sheet for vapor chamber, and manufacturing method of the vapor chamber according to the first embodiment of the present invention will be described. The vapor chamber 1 in the present embodiment is a device mounted on the electronic device E in order to cool the device D as a heat generating body housed in the electronic device E. Examples of the device D include electronic devices (devices to be cooled) that generate heat, such as a central processing unit (CPU), a light emitting diode (LED), and a power transistor, which are used in mobile terminals such as mobile phones and tablet terminals.

[0035] Here, first, the electronic device E on which the vapor chamber 1 according to the present embodiment is mounted will be described by taking a tablet terminal as an example. As shown in FIG. 1, the electronic device E (tablet terminal) includes a housing H, a device D housed in 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 in the housing H and is arranged so as to be in thermal contact with the device D. Thus, when the electronic device E is in use, the vapor chamber 1 can receive the heat generated by the device D. The heat received by the vapor chamber 1 is released to the outside of the vapor chamber 1 through the working fluid 2 described later. In this way, the device D is effectively cooled. When the electronic device E is a tablet terminal, the device D corresponds to a central processing unit or the like.

[0036] Next, the vapor chamber 1 according to the present embodiment will be described. The vapor chamber 1 has a sealed space 3 filled with a working fluid 2, and the working fluid 2 in the sealed space 3 repeats a phase change to effectively cool the device D of the electronic device E described above.

[0037] The vapor chamber 1 is generally formed in a thin flat plate shape. The planar shape of the vapor chamber 1 is arbitrary, and may be rectangular as shown in FIG. 2. In this case, the vapor chamber 1 has four linear outer edges 1a and 1b forming the outer contour in the plane. Two of these outer edges 1a are formed along the first direction X described later, and the remaining two outer edges 1b are formed along the second direction Y described later. The planar shape of the vapor chamber 1 may be, for example, a rectangle with one side being 1 cm and the other side being 3 cm, or a square with one side being 15 cm, and the planar dimensions of the vapor chamber 1 are arbitrary.

[0038] As shown in FIGS. 2 and 3, the vapor chamber 1 includes a lower metal sheet 10 (first metal sheet) having an upper surface 10a (first surface) and a lower surface 10b (second surface) provided on the side opposite to the upper surface 10a, and an upper metal sheet 20 (second metal sheet) provided on the lower metal sheet 10. Both the lower metal sheet 10 and the upper metal sheet 20 correspond to metal sheets for the vapor chamber. The upper metal sheet 20 has a lower surface 20a (surface on the side of the lower metal sheet 10) superposed on the upper surface 10a of the lower metal sheet 10 (the surface on the side of the upper metal sheet 20), and an upper surface 20b provided on the side opposite to the lower surface 20a. The device D to be cooled is attached to the lower surface 10b of the lower metal sheet 10 (especially, the lower surface of the evaporation section 11 described later).

[0039] The thickness of the vapor chamber 1 is, for example, from 0.1 mm to 1.0 mm. In FIG. 3, the case where the thickness T1 of the lower metal sheet 10 and the thickness T2 of the upper metal sheet 20 are equal is shown, but the present invention is not limited thereto, and the thickness T1 of the lower metal sheet 10 and the thickness T2 of the upper metal sheet 20 may not be equal.

[0040] A sealed space 3 filled with the working fluid 2 is formed between the lower metal sheet 10 and the upper metal sheet 20. In the present embodiment, the sealed space 3 mainly has a vapor flow path portion (a lower vapor flow path recess 12 and an upper vapor flow path recess 21 described later) through which the vapor of the working fluid 2 passes, and a liquid flow path portion 30 through which the mainly liquid working fluid 2 passes. Examples of the working fluid 2 include pure water, ethanol, methanol, acetone, and the like.

[0041] The lower metal sheet 10 and the upper metal sheet 20 are joined by diffusion bonding described later. In the forms shown in FIGS. 2 and 3, an example is shown in which both the lower metal sheet 10 and the upper metal sheet 20 are formed in a rectangular shape in plan view, but the present invention is not limited thereto. Here, the plan view means a state seen from a direction orthogonal to the surface (the lower surface 10b of the lower metal sheet 10) on which the vapor chamber 1 receives heat from the device D and the surface (the upper surface 20b of the upper metal sheet 20) that releases the received heat, and corresponds to, for example, a state of viewing the vapor chamber 1 from above (see FIG. 2) or a state of viewing it from below.

[0042] In addition, when the vapor chamber 1 is installed in a mobile terminal, depending on the posture of the mobile terminal, the vertical relationship between the lower metal sheet 10 and the upper metal sheet 20 may be disrupted. However, in the present embodiment, for the sake of convenience, the metal sheet that receives heat from the device D is referred to as the lower metal sheet 10, and the metal sheet that releases the received heat is referred to as the upper metal sheet 20, and the description will be made in a state where the lower metal sheet 10 is disposed on the lower side and the upper metal sheet 20 is disposed on the upper side.

[0043] As shown in FIG. 4, the lower metal sheet 10 has an evaporation section 11 where the working fluid 2 evaporates to generate vapor, and a lower vapor flow path recess 12 (first vapor flow path recess) provided on the upper surface 10a and formed in a rectangular shape in plan view. Among these, the lower vapor flow path recess 12 constitutes a part of the above-described sealed space 3 and is mainly configured such that the vapor generated in the evaporation section 11 passes through it.

[0044] The evaporation section 11 is disposed within the lower vapor flow path recess 12, and the vapor within the lower vapor flow path recess 12 diffuses in a direction away from the evaporation section 11, and most of the vapor is transported toward the peripheral portion having a relatively low temperature. Note that the evaporation section 11 is a portion where the working fluid 2 within the sealed space 3 evaporates by receiving heat from the device D attached to the lower surface 10b of the lower metal sheet 10. For this reason, the term “evaporation section 11” is not a concept limited to the portion overlapping with the device D, but is used as a concept including portions where the working fluid 2 can evaporate even if it does not overlap with the device D. Here, the evaporation section 11 can be provided at any location on the lower metal sheet 10, but in FIGS. 2 and 4, an example of being provided at the central portion of the lower metal sheet 10 is shown. In this case, the operation of the vapor chamber 1 can be stabilized regardless of the posture of the mobile terminal on which the vapor chamber 1 is installed.

[0045] In the present embodiment, as shown in FIGS. 3 and 4, a plurality of lower channel wall portions 13 (first channel wall portions) protruding upward (in a direction perpendicular to the bottom surface 12a) from the bottom surface 12a (described later) of the lower vapor flow channel recess 12 are provided in the lower vapor flow channel recess 12 of the lower metal sheet 10. In the present embodiment, an example is shown in which the lower channel wall portions 13 extend in an elongated shape along the first direction X (longitudinal direction, left-right direction in FIG. 4) of the vapor chamber 1. The lower channel wall portion 13 includes an upper surface 13a (first contact surface, protruding end surface) that contacts the lower surface 22a of the upper channel wall portion 22 described later. This upper surface 13a is a surface that is not etched by two etching processes described later and is formed on the same plane as the upper surface 10a of the lower metal sheet 10. Also, the lower channel wall portions 13 are spaced apart at equal intervals and arranged parallel to each other. In this way, the vapor of the working fluid 2 flows around each lower channel wall portion 13, and the vapor is configured to be transported toward the peripheral edge of the lower vapor flow channel recess 12, suppressing the vapor flow from being obstructed. Further, the lower channel wall portions 13 are arranged so as to overlap the corresponding upper channel wall portions 22 (described later) of the upper metal sheet 20 in a plan view, aiming to improve the mechanical strength of the vapor chamber 1. The width w0 of the lower channel wall portion 13 is, for example, 0.1 mm to 30 mm, preferably 0.1 mm to 2.0 mm, and the interval d between adjacent lower channel wall portions 13 is 0.1 mm to 30 mm, preferably 0.1 mm to 2.0 mm. Here, the width w0 means the dimension of the lower channel wall portion 13 in the second direction Y orthogonal to the first direction X of the lower channel wall portion 13, and corresponds to, for example, the vertical dimension in FIG. 4. Also, the height of the lower channel wall portion 13 (in other words, the depth of the lower vapor flow channel recess 12) h0 (see FIG. 3) is preferably smaller than the thickness T1 of the lower metal sheet 10 described later by 10 μm or more. In this case, the difference between the thickness T1 and the height h0, that is, the thickness of the metal material of the lower metal sheet 10 in the portion where the lower vapor flow channel recess 12 is formed can be made 10 μm or more. Therefore, the strength of the portion can be ensured, and deformation inwardly concave with respect to the pressure received from the outside air can be prevented. Such a height h0 may be 10 μm to 300 μm.For example, when the thickness T0 of the vapor chamber 1 is 0.5 mm and the thicknesses T1 of the lower metal sheet 10 and T2 of the upper metal sheet 20 are equal, the height h0 can be 200 μm.

[0046] As shown in FIGS. 3 and 4, a lower peripheral wall 14 is provided at the peripheral edge of the lower metal sheet 10. The lower peripheral wall 14 is formed so as to surround the sealed space 3, particularly the lower vapor flow path recess 12, and defines the sealed space 3. Further, lower alignment holes 15 for positioning the lower metal sheet 10 and the upper metal sheet 20 are provided at the four corners of the lower peripheral wall 14 in plan view, respectively.

[0047] In the present embodiment, the upper metal sheet 20 has substantially the same structure as the lower metal sheet 10 except that a liquid flow path portion 30 described later is not provided. The configuration of the upper metal sheet 20 will be described in more detail below.

[0048] As shown in FIGS. 3 and 5, the upper metal sheet 20 has an upper vapor flow path recess 21 (second vapor flow path recess) provided on the lower surface 20a. This upper vapor flow path recess 21 forms a part of the sealed space 3 and is mainly configured to diffuse and cool the vapor generated in the evaporation section 11. More specifically, the vapor in the upper vapor flow path recess 21 diffuses in a direction away from the evaporation section 11, and most of the vapor is transported toward the peripheral edge portion having a relatively low temperature. Further, as shown in FIG. 3, a housing member Ha that forms a part of a housing H (see FIG. 1) of a mobile terminal or the like is disposed on the upper surface 20b of the upper metal sheet 20. As a result, the vapor in the upper vapor flow path recess 21 is cooled by the outside through the upper metal sheet 20 and the housing member Ha.

[0049] In the present embodiment, as shown in FIGS. 2, 3, and 5, a plurality of upper channel wall portions 22 (second channel wall portions) protruding downward (in a direction perpendicular to the bottom surface 21a) from the bottom surface 21a of the upper vapor channel recess 21 are provided in the upper vapor channel recess 21 of the upper metal sheet 20. In the present embodiment, an example is shown in which the upper channel wall portions 22 extend in an elongated shape along the first direction X (the left-right direction in FIG. 5) of the vapor chamber 1. The upper channel wall portion 22 abuts on the upper surface 10a of the lower metal sheet 10 (more specifically, the upper surface 13a of the lower channel wall portion 13 described above) and includes a flat lower surface 22a (second abutting surface, protruding end surface) that covers the liquid channel portion 30. Further, the upper channel wall portions 22 are spaced apart at equal intervals and arranged parallel to each other. In this way, the vapor of the working fluid 2 flows around each upper channel wall portion 22, and the vapor is configured to be transported toward the peripheral edge of the upper vapor channel recess 21, suppressing the vapor flow from being obstructed. Further, the upper channel wall portion 22 is arranged so as to overlap the corresponding lower channel wall portion 13 of the lower metal sheet 10 in plan view, improving the mechanical strength of the vapor chamber 1. Note that it is preferable that the width and height of the upper channel wall portion 22 are the same as the width w0 and height h0 of the lower channel wall portion 13 described above. Here, the bottom surface 21a of the upper vapor channel recess 21 can also be referred to as a ceiling surface in the vertical arrangement relationship between the lower metal sheet 10 and the upper metal sheet 20 as shown in FIG. 3 and the like. However, since it corresponds to the inner surface of the upper vapor channel recess 21, it is referred to as the bottom surface 21a in this specification. It contacts and includes a flat lower surface 22a (second abutting surface, protruding end surface) that covers the liquid channel portion 30. Also, each upper channel wall portion 22 is spaced apart at equal intervals and arranged parallel to each other. In this way, the vapor of the working fluid 2 flows around each upper channel wall portion 22, and the vapor is configured to be transported toward the peripheral edge of the upper vapor channel recess 21, suppressing the vapor flow from being obstructed. Further, the upper channel wall portion 22 is arranged so as to overlap the corresponding lower channel wall portion 13 of the lower metal sheet 10 in plan view, improving the mechanical strength of the vapor chamber 1. Note that it is preferable that the width and height of the upper channel wall portion 22 are the same as the width w0 and height h0 of the lower channel wall portion 13 described above. Here, the bottom surface 21a of the upper vapor channel recess 21 can also be referred to as a ceiling surface in the vertical arrangement relationship between the lower metal sheet 10 and the upper metal sheet 20 as shown in FIG. 3 and the like. However, since it corresponds to the inner surface of the upper vapor channel recess 21, it is referred to as the bottom surface 21a in this specification.

[0050] As shown in FIGS. 3 and 5, an upper peripheral wall 23 is provided at the peripheral edge of the upper metal sheet 20. The upper peripheral wall 23 is formed so as to surround the sealed space 3, particularly the upper vapor channel recess 21, and defines the sealed space 3. Further, upper alignment holes 24 for positioning the lower metal sheet 10 and the upper metal sheet 20 are provided at the four corners of the upper peripheral wall 23 in plan view. That is, each upper alignment hole 24 is arranged so as to overlap the respective lower alignment holes 15 described above during temporary fixing to be described later, and the lower metal sheet 10 and the upper metal sheet 20 are configured to be positionable.

[0051] Such a lower metal sheet 10 and an upper metal sheet 20 are preferably joined to each other permanently by diffusion bonding. More specifically, as shown in FIG. 3, the upper surface 14a of the lower peripheral wall 14 of the lower metal sheet 10 abuts against the lower surface 23a of the upper peripheral wall 23 of the upper metal sheet 20, and the lower peripheral wall 14 and the upper peripheral wall 23 are joined to each other. As a result, a sealed space 3 in which the working fluid 2 is sealed is formed between the lower metal sheet 10 and the upper metal sheet 20. Further, the upper surface 13a of the lower flow path wall portion 13 of the lower metal sheet 10 abuts against the lower surface 22a of the upper flow path wall portion 22 of the upper metal sheet 20, and each lower flow path wall portion 13 and the corresponding upper flow path wall portion 22 are joined to each other. This improves the mechanical strength of the vapor chamber 1. In particular, since the lower flow path wall portions 13 and the upper flow path wall portions 22 according to the present embodiment are arranged at equal intervals, the mechanical strength at each position of the vapor chamber 1 can be equalized. Note that the lower metal sheet 10 and the upper metal sheet 20 may be joined by another method such as brazing as long as they can be joined permanently, rather than by diffusion bonding.

[0052] Further, as shown in FIG. 2, the vapor chamber 1 further includes an injection portion 4 for injecting the working fluid 2 into the sealed space 3 at one end of a pair of ends in the first direction X. The injection portion 4 has a lower injection protrusion 16 protruding from the end surface of the lower metal sheet 10 and an upper injection protrusion 25 protruding from the end surface of the upper metal sheet 20. A lower injection flow path recess 17 is formed on the upper surface of the lower injection protrusion 16, and an upper injection flow path recess 26 is formed on the lower surface of the upper injection protrusion 25. The lower injection flow path recess 17 communicates with the lower vapor flow path recess 12, and the upper injection flow path recess 26 communicates with the upper vapor flow path recess 21. The lower injection flow path recess 17 and the upper injection flow path recess 26 form an injection flow path for the working fluid 2 when the lower metal sheet 10 and the upper metal sheet 20 are joined. The working fluid 2 is injected into the sealed space 3 through the injection flow path. In the present embodiment, an example is shown in which the injection portion 4 is provided at one end of a pair of ends in the first direction X of the vapor chamber 1, but the present invention is not limited to this.

[0053] Next, the liquid flow path portion 30 of the lower metal sheet 10 will be described in more detail with reference to FIGS. 3, 4, 6, and 7.

[0054] As shown in FIGS. 3 and 4, a liquid flow path portion 30 through which the liquid working fluid 2 passes is provided on the upper surface 10a of the lower metal sheet 10 (more specifically, the upper surface 13a of each lower flow path wall portion 13). The liquid flow path portion 30 forms a part of the above-described sealed space 3 and communicates with the above-described lower vapor flow path recess 12 and upper vapor flow path recess 21.

[0055] As shown in FIG. 6, the liquid flow path portion 30 has a first main flow groove 31, a second main flow groove 32, a third main flow groove 33, and a fourth main flow groove 34. The first to fourth main flow grooves 31 to 34 each linearly extend in the first direction X so that the liquid working fluid 2 can pass through, and are arranged in this order in the above-described second direction Y. That is, the fourth main flow groove 34 is arranged on the side opposite to the side of the second main flow groove 32 with respect to the third main flow groove 33. The first to fourth main flow grooves 31 to 34 are mainly configured to transport the working fluid 2 condensed from the vapor generated in the evaporation portion 11 toward the evaporation portion 11.

[0056] A first convex portion row 41 is provided between the first main flow groove 31 and the second main flow groove 32. The first convex portion row 41 includes a plurality of first convex portions 41a arranged in the first direction X. In FIG. 6, each first convex portion 41a is formed in a rectangular shape such that the first direction X is the longitudinal direction in a plan view. A first communication groove 51 is interposed between adjacent first convex portions 41a. The first communication groove 51 is formed to extend in the second direction Y, communicates the first main flow groove 31 and the second main flow groove 32, and enables the working fluid 2 to flow back and forth between the first main flow groove 31 and the second main flow groove 32. The first communication groove 51 is a region between adjacent first convex portions 41a and is a region between the first main flow groove 31 and the second main flow groove 32.

[0057] A second convex portion row 42 is provided between the second main flow groove 32 and the third main flow groove 33. The second convex portion row 42 includes a plurality of second convex portions 42a arranged in the first direction X. In FIG. 6, each second convex portion 42a is formed in a rectangular shape in a plan view such that the first direction X is the longitudinal direction. A second connection groove 52 is interposed between adjacent second convex portions 42a. The second connection groove 52 is formed to extend in the second direction Y, communicates the second main flow groove 32 and the third main flow groove 33, and allows the working fluid 2 to flow back and forth between the second main flow groove 32 and the third main flow groove 33. The second connection groove 52 is an area between adjacent second convex portions 42a and is an area between the second main flow groove 32 and the third main flow groove 33.

[0058] The second main flow groove 32 includes a first intersection portion P1 where the first connection groove 51 communicates and a second intersection portion P2 where the second connection groove 52 communicates.

[0059] Among these, in the first intersection P1, at least a part of the first connection groove 51 faces the second convex portion 42a. As shown in FIG. 6, in the first intersection P1, the entire first connection groove 51 (the entire region in the width direction (first direction X) of the first connection groove 51) faces the second convex portion 42a. As a result, over the entire first intersection P1, the side wall 36 (the wall of the second convex portion 42a), which is on the side opposite to the side of the first connection groove 51, among the pair of side walls 35 and 36 along the first direction X of the second main flow groove 32, is arranged. In the form shown in FIG. 6, when viewed in the second direction Y, the first connection groove 51 is arranged so as to overlap the center of the second convex portion 42a in the first direction X. In this way, in the first intersection P1, the second main flow groove 32 and the first connection groove 51 intersect in a T shape. The first intersection P1 is a region between the main flow groove main body portions 31a to 34a adjacent to each other in the first direction X, and is also a region between the connection grooves 51 to 54 and the convex portions 41a to 44a adjacent to each other in the second direction Y. In other words, it is a region (that is, an overlapping region) where the main flow grooves 31 to 34 and the connection grooves 51 to 54 intersect. Here, the first main flow groove main body portions 31a to 34a constitute a part of the first to fourth main flow grooves 31 to 34, and are portions provided between the first intersection P1 and the second intersection P2, and are portions located between the convex portions 41a to 44a adjacent to each other.

[0060] Similarly, in the second intersection portion P2, at least a part of the second communication groove 52 faces the first convex portion 41a. As shown in FIG. 6, in the second intersection portion P2, the entire second communication groove 52 (the entire region in the width direction (the first direction X) of the second communication groove 52) faces the first convex portion 41a. As a result, over the entire second intersection portion P2, the side wall 35 (the wall of the first convex portion 41a) on the side opposite to the side of the second communication groove 52 among the pair of side walls 35 and 36 along the first direction X of the second main flow groove 32 is disposed. In the form shown in FIG. 6, when viewed in the second direction Y, the second communication groove 52 is disposed so as to overlap the center of the first convex portion 41a in the first direction X. In this way, in the second intersection portion P2, the second main flow groove 32 and the second communication groove 52 intersect in a T shape. The second intersection portion P2 is a region between the main flow groove main body portions 31a to 34a adjacent to each other in the first direction X and a region between the communication grooves 51 to 54 and the convex portions 41a to 44a adjacent to each other in the second direction Y. In other words, it is a region (i.e., an overlapping region) where the main flow grooves 31 to 34 and the communication grooves 51 to 54 intersect.

[0061] As described above, in the first intersection portion P1 of the second main flow groove 32, the first communication groove 51 faces the second convex portion 42a, and in the second intersection portion P2 of the second main flow groove 32, the second communication groove 52 faces the first convex portion 41a. As a result, the first communication groove 51 and the second communication groove 52 are not arranged in a straight line. That is, the first communication groove 51 communicating with one side of the second main flow groove 32 and the second communication groove 52 communicating with the other side are not arranged in a straight line.

[0062] In the present embodiment, the first convex portion 41a and the second convex portion 42a have the same shape, and the arrangement pitch of the first convex portion 41a and the arrangement pitch of the second convex portion 42a are the same. And the first convex portion 41a and the second convex portion 42a are arranged so as to be shifted from each other in the first direction X by a dimension that is half of this arrangement pitch.

[0063] In addition, in the present embodiment, the first intersection P1 and the second intersection P2 of the second main flow groove 32 are adjacent to each other. That is, no other intersection (for example, a third intersection P3 as shown in FIG. 14 described later) is interposed between the first intersection P1 and the second intersection P2. The second main flow groove 32 includes a plurality of first intersections P1 and a plurality of second intersections P2, and the first intersections P1 and the second intersections P2 are alternately arranged in the first direction X. That is, a pair of side walls 35, 36 of the second main flow groove 32 are intermittently formed, and the disconnection positions of the side walls 35, 36 are shifted from each other in the first direction X.

[0064] By the way, a third convex portion row 43 is provided between the third main flow groove 33 and the fourth main flow groove 34. This third convex portion row 43 includes a plurality of third convex portions 43a arranged in the first direction X, similar to the first convex portion row 41. A third communication groove 53 is interposed between adjacent third convex portions 43a. The third communication groove 53 is formed to extend in the second direction Y, communicates the third main flow groove 33 and the fourth main flow groove 34, and enables the working fluid 2 to flow back and forth between the third main flow groove 33 and the fourth main flow groove 34. The third communication groove 53 is a region between adjacent third convex portions 43a and is a region between the third main flow groove 33 and the fourth main flow groove 34.

[0065] The third main flow groove 33 includes a first intersection P1 where the second communication groove 52 communicates and a second intersection P2 where the third communication groove 53 communicates. Among these, in the first intersection P1, at least a part of the second communication groove 52 faces the third convex portion 43a. In FIG. 6, in the first intersection P1, the entire second communication groove 52 (the entire region in the width direction (the first direction X) of the second communication groove 52) faces the third convex portion 43a. As a result, along the first direction X of the third main flow groove 33, the side wall 36 (the wall of the third convex portion 43a) on the side opposite to the side of the second communication groove 52 exists over the entire first intersection P1 among the pair of side walls 35, 36. In the form shown in FIG. 6, when viewed in the second direction Y, the second communication groove 52 is arranged so as to overlap the center of the third convex portion 43a in the first direction X. In this way, in the first intersection P1, the third main flow groove 33 and the second communication groove 52 intersect in a T shape.

[0066] Similarly, in the second intersection portion P2, at least a part of the third communication groove 53 faces the second convex portion 42a. In FIG. 6, in the second intersection portion P2, the entire third communication groove 53 (the entire region in the width direction (the first direction X) of the third communication groove 53) faces the second convex portion 42a. As a result, over the entire second intersection portion P2, the side wall 35 (the wall of the second convex portion 42a) on the side opposite to the side of the third communication groove 53 among the pair of side walls 35, 36 along the first direction X of the third main groove 33 is disposed. In the form shown in FIG. 6, when viewed in the second direction Y, the third communication groove 53 is disposed so as to overlap the center of the second convex portion 42a in the first direction X. In this way, in the second intersection portion P2, the third main groove 33 and the third communication groove 53 intersect in a T shape.

[0067] That is, in the present embodiment, the first convex portion 41a, the second convex portion 42a, and the third convex portion 43a have the same shape, and the arrangement pitch of the first convex portion 41a, the arrangement pitch of the second convex portion 42a, and the arrangement pitch of the third convex portion 43a are the same. And the second convex portion 42a and the third convex portion 43a are displaced from each other in the first direction X by a dimension that is half of this arrangement pitch. As a result, the first convex portion 41a and the third convex portion 43a are disposed at the same position in the first direction X, and when viewed in the second direction Y, the first convex portion 41a and the third convex portion 43a overlap.

[0068] In the present embodiment, similar to the second main groove 32, the first intersection portion P1 and the second intersection portion P2 of the third main groove 33 are adjacent to each other. And the third main groove 33 includes a plurality of first intersection portions P1 and a plurality of second intersection portions P2, and the first intersection portions P1 and the second intersection portions P2 are alternately arranged in the first direction X. That is, the pair of side walls 35, 36 of the third main groove 33 are formed intermittently, and the breaking positions of the respective side walls 35, 36 are displaced from each other in the first direction X.

[0069] Since the first convex portion 41a, the second convex portion 42a, and the third convex portion 43a are arranged as described above, in this embodiment, the arrangement of the first convex portion 41a, the second convex portion 42a, and the third convex portion 43a is in a staggered pattern. As a result, the first communication groove 51, the second communication groove 52, and the third communication groove 53 are also arranged in a staggered pattern.

[0070] In FIG. 6, a set of main flow grooves when taking the above-described first to fourth main flow grooves 31 to 34 as one set is shown. A plurality of such sets may be provided, and as a whole, a large number of main flow grooves 31 to 34 may be formed on the upper surface 13a of the lower flow path wall portion 13. Note that the main flow grooves constituting the liquid flow path portion 30 do not necessarily need to be configured with the first to fourth main flow grooves 31 to 34 as one set. As long as at least three main flow grooves are formed, the number of main flow grooves is not limited to a multiple of 4 and is arbitrary.

[0071] In this case, on the side of the fourth main flow groove 34 opposite to the side of the third main flow groove 33, the above-described first main flow groove 31 is provided, and a fourth convex portion row 44 is provided between the fourth main flow groove 34 and the first main flow groove 31. Similar to the above-described second convex portion row 42, this fourth convex portion row 44 includes a plurality of fourth convex portions 44a arranged in the first direction X. The fourth convex portion 44a and the second convex portion 42a are arranged at the same position in the first direction X, and when viewed in the second direction Y, the fourth convex portion 44a and the second convex portion 42a overlap. A fourth communication groove 54 is interposed between adjacent fourth convex portions 44a. The fourth communication groove 54 is formed to extend in the second direction Y, communicates the fourth main flow groove 34 and the first main flow groove 31, and allows the working fluid 2 to flow back and forth between the fourth main flow groove 34 and the first main flow groove 31. The fourth communication groove 54 is the region between adjacent fourth convex portions 44a and is the region between the fourth main flow groove 34 and the first main flow groove 31.

[0072] The fourth main flow channel 34 has a first intersection part P1 and a second intersection part P2 similar to those of the second main flow channel 32. Here, in the first intersection part P1, a third communication channel 53 communicates with the fourth main flow channel 34, and in the second intersection part P2, a fourth communication channel 54 communicates with the fourth main flow channel 34. Also, the first main flow channel 31 has a first intersection part P1 and a second intersection part P2 similar to those of the third main flow channel 33. Here, in the first intersection part P1, the fourth communication channel 54 communicates with the first main flow channel 31, and in the second intersection part P2, the first communication channel 51 communicates with the first main flow channel 31. Since the first intersection part P1 and the second intersection part P2 in the first main flow channel 31 and the fourth main flow channel 34 are the same as those in the second main flow channel 32 and the third main flow channel 33, detailed description thereof is omitted here.

[0073] Each of the convex portions 41a to 44a may be arranged in a rectangular shape and in a staggered pattern over the entire liquid flow path portion 30 as described above.

[0074] Incidentally, it is preferable that the widths w1 (dimensions in the second direction Y) of the first to fourth main flow channels 31 to 34 are larger than the widths w2 (dimensions in the second direction Y) of the first to fourth convex portions 41a to 44a. In this case, the ratio of the first to fourth main flow channels 31 to 34 occupying the upper surface 13a of the lower flow path wall portion 13 can be increased. For this reason, the flow path density of the main flow channels 31 to 34 on the upper surface 13a can be increased, and the transport function of the liquid working fluid 2 can be improved. For example, the widths w1 of the first to fourth main flow channels 31 to 34 may be 30 μm to 200 μm, and the widths w2 of the first to fourth convex portions 41a to 44a may be 20 μm to 180 μm.

[0075] It is preferable that the depths h1 of the first to fourth main flow channels 31 to 34 are smaller than the depth h0 of the lower vapor flow path recess 12 described above. In this case, the capillary action of the first to fourth main flow channels 31 to 34 can be enhanced. For example, the depth h1 of the first to fourth main flow channels 31 to 34 is preferably about half of h0, and may be 5 μm to 180 μm.

[0076] Also, it is preferable that the widths w3 (dimensions in the first direction X) of the first to fourth connection grooves 51 to 54 are smaller than the widths w1 of the first to fourth main flow grooves 31 to 34. In this case, while the liquid working fluid 2 is being transported toward the evaporation section 11 in each of the main flow grooves 31 to 34, the flow of the working fluid 2 into the connection grooves 51 to 54 can be suppressed, and the transport function of the working fluid 2 can be improved. On the other hand, when dry-out occurs in any of the main flow grooves 31 to 34, the working fluid 2 can be moved from the adjacent main flow grooves 31 to 34 through the corresponding connection grooves 51 to 54, quickly eliminating the dry-out and ensuring the transport function of the working fluid 2. That is, if the first to fourth connection grooves 51 to 54 can communicate the adjacent main flow grooves 31 to 34 with each other, even if they are smaller than the width w1 of the main flow grooves 31 to 34, they can exhibit their functions. The widths w3 of such first to fourth connection grooves 51 to 54 may be, for example, 20 μm to 180 μm.

[0077] The depths h3 of the first to fourth connection grooves 51 to 54 may be shallower than the depths h1 of the first to fourth main flow grooves 31 to 34 according to their widths w3. For example, when the depth h1 of the first to fourth main flow grooves 31 to 34 is 50 μm, the depth h3 (not shown) of the first to fourth connection grooves 51 to 54 may be 40 μm.

[0078] Here, a method for checking the widths and depths of the main flow grooves 31 to 34 and the widths and depths of the connection grooves 51 to 54 from the completed vapor chamber 1 will be described later.

[0079] The cross-sectional shapes (cross-sections in the second direction Y) of the first to fourth main flow grooves 31 to 34 are not particularly limited, and can be, for example, rectangular, curved, semi-circular, or V-shaped. The same applies to the cross-sectional shapes (cross-sections in the first direction X) of the first to fourth connection grooves 51 to 54. In FIG. 7, an example is shown in which the cross-sections of the first to fourth main flow grooves 31 to 34 are formed in a rectangular shape.

[0080] Incidentally, the liquid flow path portion 30 described above is formed on the upper surface 13a of the lower flow path wall portion 13 of the lower metal sheet 10. On the other hand, in the present embodiment, the lower surface 22a of the upper flow path wall portion 22 of the upper metal sheet 20 is formed in a flat shape. As a result, each of the main flow grooves 31 to 34 of the liquid flow path portion 30 is covered with the flat lower surface 22a. In this case, as shown in FIG. 7, a pair of side walls 35 and 36 extending in the first direction X of the main flow grooves 31 to 34 and the lower surface 22a of the upper flow path wall portion 22 can form two angular portions 37 at right angles or acute angles, and the capillary action at these two angular portions 37 can be enhanced. That is, two angular portions 38 can also be formed by the bottom surface (the surface on the side of the lower surface 10b of the lower metal sheet 10) of the main flow grooves 31 to 34 and the pair of side walls 35 and 36 of the main flow grooves 31 to 34. However, when the main flow grooves 31 to 34 are formed by etching as described later, the angular portions 38 on the bottom surface side tend to be formed with rounded shapes. For this reason, by forming the lower surface 22a of the upper flow path wall portion 22 in a flat shape so as to cover the main flow grooves 31 to 34 and the communication grooves 51 to 54, the capillary action can be enhanced at the angular portions 37 on the side of the lower surface 22a of the upper flow path wall portion 22. In FIG. 7, for the sake of clarity of the drawing, only for the first main flow groove 31, the side walls 35, 36 and the angular portions 37, 38 are shown, and for the second to fourth main flow grooves 32 to 34, the side walls 35, 36 and the angular portions 37, 38 are omitted.

[0081] Note that the materials used for the lower metal sheet 10 and the upper metal sheet 20 are not particularly limited as long as they are materials with good thermal conductivity. For example, it is preferable that the lower metal sheet 10 and the upper metal sheet 20 are formed of copper (oxygen-free copper) or a copper alloy. Thereby, the thermal conductivity of the lower metal sheet 10 and the upper metal sheet 20 can be increased. Therefore, the heat dissipation efficiency of the vapor chamber 1 can be increased. Alternatively, if a desired heat dissipation efficiency can be obtained, other metal materials such as aluminum or other metal alloy materials such as stainless steel can also be used for these metal sheets 10 and 20.

[0082] Next, the operation of the present embodiment having such a configuration will be described. Here, first, the manufacturing method of the vapor chamber 1 will be described with reference to FIGS. 8 to 13, but the description of the half-etching process of the upper metal sheet 20 will be simplified. Note that FIGS. 8 to 13 show the same cross section as the cross-sectional view of FIG. 3.

[0083] First, as shown in FIG. 8, as a preparation step, a flat metal material sheet M is prepared.

[0084] Subsequently, as shown in FIG. 9, the metal material sheet M is half-etched to form a lower vapor flow path recess 12 that constitutes a part of the sealed space 3. In this case, first, a first resist film (not shown) is formed on the upper surface Ma of the metal material sheet M in a pattern corresponding to a plurality of lower flow path wall portions 13 and a lower peripheral wall 14 by photolithography technology. Subsequently, as a first half-etching step, the upper surface Ma of the metal material sheet M is half-etched. As a result, the portion of the upper surface Ma of the metal material sheet M corresponding to the resist opening (not shown) of the first resist film is half-etched, and a lower vapor flow path recess 12, a lower flow path wall portion 13, and a lower peripheral wall 14 as shown in FIG. 9 are formed. At this time, the lower injection flow path recess 17 shown in FIGS. 2 and 4 is also formed simultaneously, and the metal material sheet M is etched from the upper surface Ma and the lower surface so as to have an outer contour shape as shown in FIG. 4, and a predetermined outer contour shape is obtained. After the first half-etching step, the first resist film is removed. Note that half-etching means etching for forming a recess that does not penetrate the material. Therefore, the depth of the recess formed by half-etching is not necessarily limited to half of the thickness of the lower metal sheet 10. As the etching solution, for example, an iron chloride-based etching solution such as an aqueous solution of ferric chloride or an aqueous solution of copper chloride such as an aqueous solution of copper chloride can be used.

[0085] After the lower vapor flow path recess 12 is formed, as shown in FIG. 10, a liquid flow path portion 30 is formed on the upper surface 13a of the lower flow path wall portion 13.

[0086] In this case, first, a second resist film (not shown) is formed on the upper surface 13a of the lower channel wall portion 13 in a pattern corresponding to the first to fourth convex portions 41a to 44a of the liquid channel portion 30 by photolithography technology. Subsequently, as a second half-etching step, the upper surface 13a of the lower channel wall portion 13 is half-etched. As a result, the portion of the upper surface 13a corresponding to the resist opening (not shown) of the second resist film is half-etched, and the liquid channel portion 30 is formed on the upper surface 13a of the lower channel wall portion 13. That is, the convex portions 41a to 44a are formed on the upper surface 13a. The first to fourth main channels 31 to 34 and the first to fourth connecting channels 51 to 54 are defined by these convex portions 41a to 44a. After the second half-etching step, the second resist film is removed.

[0087] In this way, the lower metal sheet 10 with the liquid channel portion 30 formed thereon is obtained. Note that, as a second half-etching step which is a step different from the first half-etching step, by forming the liquid channel portion 30, it becomes possible to easily form the main channels 31 to 34 and the connecting channels 51 to 54 at a depth different from the depth h0 of the lower vapor channel recess 12. However, the lower vapor channel recess 12 and the main channels 31 to 34 and the connecting channels 51 to 54 may be formed in the same half-etching step. In this case, the number of half-etching steps can be reduced, and the manufacturing cost of the vapor chamber 1 can be reduced.

[0088] On the other hand, in the same manner as the lower metal sheet 10, the upper metal sheet 20 is half-etched from the lower surface 20a, and the upper vapor channel recess 21, the upper channel wall portion 22, and the upper peripheral wall 23 are formed. In this way, the above-described upper metal sheet 20 is obtained.

[0089] Next, as shown in FIG. 11, as a temporary fixing step, the lower metal sheet 10 having the lower steam flow path recess 12 and the upper metal sheet 20 having the upper steam flow path recess 21 are temporarily fixed. In this case, first, the lower metal sheet 10 and the upper metal sheet 20 are positioned by using the lower alignment holes 15 (see FIGS. 2 and 4) of the lower metal sheet 10 and the upper alignment holes 24 (see FIGS. 2 and 5) of the upper metal sheet 20. Subsequently, the lower metal sheet 10 and the upper metal sheet 20 are fixed. The fixing method is not particularly limited. For example, the lower metal sheet 10 and the upper metal sheet 20 may be fixed by performing resistance welding on the lower metal sheet 10 and the upper metal sheet 20. In this case, as shown in FIG. 11, it is preferable to perform spot resistance welding using the electrode bar 40. Laser welding may be performed instead of resistance welding. Alternatively, the lower metal sheet 10 and the upper metal sheet 20 may be ultrasonically joined and fixed by irradiating ultrasonic waves. Furthermore, an adhesive may be used, but it is preferable to use an adhesive having no organic components or having few organic components. In this way, the lower metal sheet 10 and the upper metal sheet 20 are fixed in a positioned state.

[0090] After temporary fixing, as shown in FIG. 12, as a permanent joining process, the lower metal sheet 10 and the upper metal sheet 20 are permanently joined by diffusion bonding. Diffusion bonding is a method in which the lower metal sheet 10 and the upper metal sheet 20 to be joined are brought into close contact with each other, and in a controlled atmosphere such as in a vacuum or an inert gas, pressure is applied in the direction of bringing the metal sheets 10 and 20 into close contact with each other and heated to utilize the diffusion of atoms occurring on the joining surface for joining. In diffusion bonding, the materials of the lower metal sheet 10 and the upper metal sheet 20 are heated to a temperature close to the melting point, but since it is lower than the melting point, it is possible to avoid the lower metal sheet 10 and the upper metal sheet 20 from melting and deforming. More specifically, the upper surface 14a of the lower peripheral wall 14 of the lower metal sheet 10 and the lower surface 23a of the upper peripheral wall 23 of the upper metal sheet 20 become the joining surface and are diffusion bonded. As a result, a sealed space 3 is formed between the lower metal sheet 10 and the upper metal sheet 20 by the lower peripheral wall 14 and the upper peripheral wall 23. Further, an injection channel for the working fluid 2 communicating with the sealed space 3 is formed by the lower injection channel recess 17 (see FIGS. 2 and 4) and the upper injection channel recess 26 (see FIGS. 2 and 5). Furthermore, the upper surface 13a of the lower channel wall portion 13 of the lower metal sheet 10 and the lower surface 22a of the upper channel wall portion 22 of the upper metal sheet 20 become the joining surface and are diffusion bonded, improving the mechanical strength of the vapor chamber 1. The liquid channel portion 30 formed on the upper surface 13a of the lower channel wall portion 13 remains as a channel for the liquid working fluid 2.

[0091] After permanent joining, as shown in FIG. 13, as an encapsulation process, the working fluid 2 is injected into the sealed space 3 from the injection portion 4 (see FIG. 2). At this time, first, the sealed space 3 is evacuated and depressurized, and then the working fluid 2 is injected into the sealed space 3. During injection, the working fluid 2 passes through the injection channel formed by the lower injection channel recess 17 and the upper injection channel recess 26. For example, the filling amount of the working fluid 2 may be 10% to 30% with respect to the total volume of the sealed space 3, although it also depends on the configuration of the liquid channel portion 30 inside the vapor chamber 1.

[0092] After the injection of the working fluid 2, the above-described injection channel is sealed. For example, the injection portion 4 may be irradiated with a laser to partially melt the injection portion 4 to seal the injection channel. By this, the communication between the sealed space 3 and the outside is blocked, and the working fluid 2 is enclosed in the sealed space 3. In this way, leakage of the working fluid 2 in the sealed space 3 to the outside is prevented. Note that, for sealing, the injection portion 4 may be caulked or brazed.

[0093] As described above, the vapor chamber 1 according to the present embodiment is obtained.

[0094] Next, a method of operating the vapor chamber 1, that is, a method of cooling the device D will be described.

[0095] The vapor chamber 1 obtained as described above is installed in a housing H such as a mobile terminal, and a device D such as a CPU, which is an object to be cooled, is attached to the lower surface 10b of the lower metal sheet 10. Since the amount of the working fluid 2 injected into the sealed space 3 is small, the liquid working fluid 2 in the sealed space 3 adheres to the wall surface of the sealed space 3, that is, the wall surface of the lower vapor flow path recess 12, the wall surface of the upper vapor flow path recess 21, and the wall surface of the liquid flow path portion 30 due to its surface tension.

[0096] When the device D generates heat in this state, the working fluid 2 present in the evaporation portion 11 of the lower vapor flow path recess 12 receives heat from the device D. The received heat is absorbed as latent heat and the working fluid 2 evaporates (vaporizes), generating vapor of the working fluid 2. Most of the generated vapor diffuses in the lower vapor flow path recess 12 and the upper vapor flow path recess 21 that constitute the sealed space 3 (see the solid arrows in FIG. 4). The vapor in the upper vapor flow path recess 21 and the lower vapor flow path recess 12 moves away from the evaporation portion 11, and most of the vapor is transported toward the peripheral portion of the vapor chamber 1 where the temperature is relatively low. The diffused vapor dissipates heat to the lower metal sheet 10 and the upper metal sheet 20 and is cooled. The heat received by the lower metal sheet 10 and the upper metal sheet 20 from the vapor is transmitted to the outside through the housing member Ha (see FIG. 3).

[0097] The steam loses the latent heat absorbed in the evaporation section 11 by dissipating heat to the lower metal sheet 10 and the upper metal sheet 20, and condenses. The working fluid 2 that has condensed into a liquid state adheres to the wall surface of the lower steam flow path recess 12 or the wall surface of the upper steam flow path recess 21. Here, since the working fluid 2 continues to evaporate in the evaporation section 11, the working fluid 2 in the portion of the liquid flow path section 30 other than the evaporation section 11 is transported toward the evaporation section 11 (see the dashed arrow in FIG. 4). As a result, the liquid working fluid 2 adhering to the wall surface of the lower steam flow path recess 12 and the wall surface of the upper steam flow path recess 21 moves toward the liquid flow path section 30 and enters the liquid flow path section 30. That is, it enters the first to fourth main flow grooves 31 to 34 through the first to fourth communication grooves 51 to 54, and the liquid working fluid 2 fills the main flow grooves 31 to 34 and the communication grooves 51 to 54. For this reason, the filled working fluid 2 obtains a driving force toward the evaporation section 11 by the capillary action of each of the main flow grooves 31 to 34, and is smoothly transported toward the evaporation section 11.

[0098] In the liquid flow path section 30, each of the main flow grooves 31 to 34 communicates with the other adjacent main flow grooves 31 to 34 via the corresponding communication grooves 51 to 54. As a result, the liquid working fluid 2 moves back and forth between the adjacent main flow grooves 31 to 34, and the occurrence of dry-out in the main flow grooves 31 to 34 is suppressed. For this reason, capillary action is imparted to the working fluid 2 in each of the main flow grooves 31 to 34, and the working fluid 2 is smoothly transported toward the evaporation section 11.

[0099] Further, since each of the main flow grooves 31 to 34 includes the first intersection portion P1 and the second intersection portion P2 described above, the capillary action acting on the working fluid 2 in each of the main flow grooves 31 to 34 is prevented from being lost. Here, for example, when the first communication groove 51 and the second communication groove 52 are arranged in a straight line via the second main flow groove 32, both of the pair of side walls 35, 36 do not exist at the intersection with the second main flow groove 32. In this case, at the intersection portion, the capillary action in the direction toward the evaporation section 11 is lost, and the driving force of the working fluid 2 toward the evaporation section 11 may be reduced.

[0100] In contrast, in the present embodiment, as described above, the first communication groove 51 communicating with the second main flow groove 32 on one side and the second communication groove 52 communicating with the second main flow groove 32 on the other side are not arranged in a straight line. In this case, as shown in FIG. 6, at the first intersection portion P1, among the pair of side walls 35 and 36 along the first direction X of the second main flow groove 32, the side wall 36 on the side opposite to the side of the first communication groove 51 is arranged. As a result, at the first intersection portion P1, it is possible to prevent the capillary action in the direction toward the evaporation portion 11 from being lost. Similarly, at the second intersection portion P2, since the side wall 35 on the side opposite to the side of the second communication groove 52 is arranged, it is possible to prevent the capillary action in the direction toward the evaporation portion 11 from being lost. Therefore, at each of the intersection portions P1 and P2, it is possible to suppress a reduction in capillary action, and it is possible to continuously apply capillary action to the working fluid 2 flowing toward the evaporation portion 11.

[0101] And in the present embodiment, the first intersection portion P1 and the second intersection portion P2 of the second main flow groove 32 are alternately arranged. That is, at the first intersection portion P1 of the second main flow groove 32, capillary action is applied to the working fluid 2 in the second main flow groove 32 by the side wall 36 on the side of the second communication groove 52, but at the second intersection portion P2, capillary action can be applied to the working fluid 2 in the second main flow groove 32 by the side wall 35 on the side of the first communication groove 51, which is opposite to the side wall 36. Therefore, the capillary action acting on the working fluid 2 in the second main flow groove 32 can be equalized in the width direction (second direction Y).

[0102] In the present embodiment, the first main flow groove 31, the third main flow groove 33, and the fourth main flow groove 34 each have the first intersection portion P1 and the second intersection portion P2 similar to those of the second main flow groove 32. As a result, it is possible to suppress a reduction in the capillary action applied to the working fluid 2 in the first to fourth main flow grooves 31 to 34.

[0103] The working fluid 2 that has reached the evaporation portion 11 is evaporated again by receiving heat from the device D. In this way, the working fluid 2 refluxes in the vapor chamber 1 while repeating phase changes, that is, evaporation and condensation, and transfers and releases the heat of the device D. As a result, the device D is cooled.

[0104] By the way, in the present embodiment, as described above, in the second main flow groove 32, the first connection groove 51 and the second connection groove 52 are not arranged in a straight line. For this reason, depending on the posture of the mobile terminal on which the vapor chamber 1 is installed, the second direction Y may be along the gravitational direction rather than the first direction X. In such a posture, if the first connection groove 51 and the second connection groove 52 are arranged in a straight line, a part of the working fluid 2 in each of the main flow grooves 31 to 34 is considered to flow toward one side in the second direction Y under the influence of gravity, and the working fluid 2 is biased toward that one side.

[0105] However, when each of the main flow grooves 31 to 34 includes the first intersection portion P1 and the second intersection portion P2 as in the present embodiment, it is possible to suppress the working fluid 2 from flowing linearly toward one side in the second direction Y. That is, while the working fluid 2 is flowing toward one side in the second direction Y, it can proceed toward the evaporation portion 11 through the main flow grooves 31 to 34, and it is possible to suppress the flow of the working fluid 2 toward the evaporation portion 11 from weakening. For this reason, even when the posture of the vapor chamber 1 is such that gravity acts in a direction that inhibits the transport function of the working fluid 2, the transport function of the liquid working fluid 2 can be improved.

[0106] By the way, the sealed space 3 is depressurized as described above. As a result, the lower metal sheet 10 and the upper metal sheet 20 are receiving pressure from the outside air in a direction of being recessed inward. Here, when the first connection groove 51 and the second connection groove 52 are arranged in a straight line via the second main flow groove 32, an intersection portion where the second main flow groove 32, the first connection groove 51, and the second connection groove 52 intersect in a cross shape is formed. In this case, along the groove extending in the second direction Y orthogonal to the first direction X, the lower metal sheet 10 and the upper metal sheet 20 may be recessed inward, and the recess may be formed so as to cross the second main flow groove 32. In this case, the flow path cross-sectional area of the second main flow groove 32 may become small, and the flow path resistance of the working fluid 2 may increase.

[0107] In contrast, in the present embodiment, at the first intersection P1 of the second main flow groove 32, the first connection groove 51 faces the second convex portion 42a. As a result, even when the lower metal sheet 10 and the upper metal sheet 20 are recessed inward along the first connection groove 51, it is possible to prevent the recess from crossing the second main flow groove 32. Therefore, the flow channel cross-sectional area of the second main flow groove 32 can be ensured, and it is possible to prevent the flow of the working fluid 2 from being obstructed. For example, in a vapor chamber for a mobile terminal that requires thinness, it may become difficult to suppress dent deformation due to its thinness. However, even when the vapor chamber 1 according to the present embodiment is applied to such a vapor chamber for a mobile terminal, according to the present embodiment, dent deformation can be effectively suppressed. For example, when the thickness (remaining thickness) of the portion of the lower metal sheet 10 where the main flow grooves 31 to 34 and the connection grooves 51 to 54 are formed is about 50 μm to 150 μm, in order to suppress dent deformation, it may be effective to arrange the first convex portions 41a to the fourth convex portions 44a in a staggered manner. Also, when oxygen-free copper is used as a material with good thermal conductivity, it may become difficult to suppress dent deformation due to the low mechanical strength of the material. However, even when the vapor chamber 1 according to the present embodiment is formed of oxygen-free copper, dent deformation can be effectively suppressed.

[0108] Thus, according to this embodiment, as described above, at the first intersection P1, the side wall 36 of the pair of side walls 35 and 36 of the second main flow channel 32, which is opposite to the side of the first connection groove 51, can be arranged. Therefore, even when the lower metal sheet 10 and the upper metal sheet 20 are recessed inward along the first connection groove 51 due to the pressure of the outside air, the recess can be prevented from crossing the second main flow channel 32. Similarly, at the second intersection P2, the side wall 35 of the pair of side walls 35 and 36 of the second main flow channel 32, which is opposite to the side of the second connection groove 52, can be arranged. Therefore, even when the lower metal sheet 10 and the upper metal sheet 20 are recessed along the first connection groove 51 due to the pressure of the outside air, the recess can be prevented from crossing the second main flow channel 32. For this reason, the flow path cross-sectional area of the second main flow channel 32 can be ensured, and the flow of the working fluid 2 can be prevented from being obstructed. As a result, the transport function of the liquid working fluid 2 can be improved, and the heat transport efficiency can be improved.

[0109] Further, according to this embodiment, the second main flow channel 32 of the liquid flow path portion 30 includes a first intersection P1 where the first connection groove 51 faces the second convex portion 42a, and a second intersection P2 where the second connection groove 52 faces the first convex portion 41a. As a result, at the first intersection P1, the side wall 36 of the pair of side walls 35 and 36 of the second main flow channel 32, which is opposite to the side of the first connection groove 51, can be arranged, and at the second intersection P2, the side wall 35 of the pair of side walls 35 and 36 of the second main flow channel 32, which is opposite to the side of the second connection groove 52, can be arranged. For this reason, capillary action can be continuously imparted to the working fluid 2 flowing toward the evaporation portion 11. In addition, at the first intersection P1 and the second intersection P2, the side walls 35 and 36 arranged on opposite sides of each other can impart capillary action to the working fluid 2 in the second main flow channel 32. Therefore, the capillary action imparted to the working fluid 2 in the second main flow channel 32 can be equalized in the second direction Y. As a result, it is possible to suppress a decrease in the propulsion of the working fluid 2 flowing toward the evaporation portion 11 at the intersections P1 and P2, improve the transport function of the liquid working fluid 2, and improve the heat transport efficiency.

[0110] Further, according to the present embodiment, the first intersection portion P1 and the second intersection portion P2 of the second main flow groove 32 are adjacent to each other. This can equalize the capillary action acting on the working fluid 2 in the second main flow groove 32 in the width direction.

[0111] Further, according to the present embodiment, a plurality of first intersection portions P1 and a plurality of second intersection portions P2 of the second main flow groove 32 are alternately arranged. This can further equalize the capillary action imparted to the working fluid 2 in the second main flow groove 32.

[0112] Further, according to the present embodiment, the liquid flow path portion 30 has a third main flow groove 33, and the third main flow groove 33 includes a first intersection portion P1 where the second connection groove 52 faces the third convex portion 43a, and a second intersection portion P2 where the third connection groove 53 faces the second convex portion 42a. Thus, in the same manner as the second main flow groove 32 described above, even when the lower metal sheet 10 and the upper metal sheet 20 are recessed inward by the pressure of the outside air, it is possible to prevent the recess from crossing the third main flow groove 33. In addition, the capillary action imparted to the working fluid 2 in the third main flow groove 33 can be equalized. Therefore, the flow path cross-sectional area of the third main flow groove 33 can be ensured. In particular, in the present embodiment, since the first main flow groove 31 and the fourth main flow groove 34 also include the same first intersection portion P1 and second intersection portion P2, the capillary action imparted to the working fluid 2 is equalized over the entire liquid flow path portion 30, and the flow path cross-sectional areas of the respective main flow grooves 31 to 34 can be ensured, and the transport function of the working fluid 2 can be further improved.

[0113] Further, according to the present embodiment, since the first intersection portion P1 and the second intersection portion P2 of the third main flow groove 33 are adjacent to each other, it is possible to further suppress the uneven application of the capillary action. In particular, since a plurality of first intersection portions P1 and a plurality of second intersection portions P2 of the third main flow groove 33 are alternately arranged, the capillary action imparted to the working fluid 2 in the third main flow groove 33 can be further equalized.

[0114] Also, according to the present embodiment, the lower surface 22a of the upper channel wall portion 22 of the upper metal sheet 20 that abuts against the upper surface 13a of the lower channel wall portion 13 is flat and covers the second main channel 32. As a result, in the cross section of each of the main channels 31 to 34 and each of the connecting channels 51 to 54, two angular portions 37 (see FIG. 7) that are right-angled or acute-angled can be formed, and the capillary action acting on the working fluid 2 in each of the main channels 31 to 34 and each of the connecting channels 51 to 54 can be enhanced.

[0115] Also, according to the present embodiment, the widths w1 of the first to fourth main channels 31 to 34 are larger than the widths w2 of the first to fourth convex portions 41a to 44a. As a result, the ratio of the first to fourth main channels 31 to 34 occupying the upper surface 13a of the lower channel wall portion 13 can be increased. Therefore, the transport function of the liquid working fluid 2 can be improved.

[0116] Furthermore, according to the present embodiment, the widths w3 of the first to fourth connecting channels 51 to 54 are smaller than the widths w1 of the first to fourth main channels 31 to 34. As a result, while the liquid working fluid 2 is being transported toward the evaporation portion 11 in each of the main channels 31 to 34, the flow of the working fluid 2 into the connecting channels 51 to 54 can be suppressed, and the transport function of the working fluid 2 can be improved. On the other hand, when dry-out occurs in any of the main channels 31 to 34, the working fluid 2 can be moved from the adjacent main channels 31 to 34 through the corresponding connecting channels 51 to 54, quickly eliminating the dry-out and ensuring the transport function of the working fluid 2.

[0117] In the above-described embodiment, an example has been described in which the entire first connection groove 51 faces the second convex portion 42a at the first intersection portion P1 of the second main flow groove 32, and the entire second connection groove 52 faces the first convex portion 41a at the second intersection portion P2. However, the present invention is not limited to this, and at the first intersection portion P1, a part of the first connection groove 51 (a part of the region in the width direction (first direction X) of the first connection groove 51) may face the second convex portion 42a. Further, at the second intersection portion P2, a part of the second connection groove 52 may face the first convex portion 41a. That is, when viewed in the second direction Y, if the first connection groove 51 and the second connection groove 52 do not entirely overlap (if the first connection groove 51 and the second connection groove 52 are not arranged in a straight line), they may partially overlap. Even in this case, on a part of the first intersection portion P1 in the first direction X, the side wall 36 of the second main flow groove 32 can be arranged, and on a part of the second intersection portion P2 in the first direction X, the side wall 35 of the second main flow groove 32 can be arranged. Therefore, it is possible to prevent the capillary action in the direction toward the evaporation portion 11 from being lost at the first intersection portion P1. The same applies to the first intersection portion P1 and the second intersection portion P2 in each of the first main flow groove 31, the third main flow groove 33, and the fourth main flow groove 34.

[0118] In the above-described embodiment, an example has been described in which the first to fourth main flow grooves 31 to 34 each include the first intersection portion P1 and the second intersection portion P2. However, the present invention is not limited to this, and at least one of the main flow grooves 31 to 34 in the liquid flow path portion 30 may include the first intersection portion P1 and the second intersection portion P2.

[0119] For example, the liquid flow path portion 30 may be configured as shown in FIG. 14. In the form shown in FIG. 14, the second main flow groove 32 and the fourth main flow groove 34 include a first intersection portion P1 and a second intersection portion P2 in the same manner as the form shown in FIG. 6. However, the first main flow groove 31 and the third main flow groove 33 do not include a first intersection portion P1 and a second intersection portion P2 as in the form shown in FIG. 6. That is, in the first main flow groove 31, a fourth communication groove 54 and a first communication groove 51 extending in the second direction Y are arranged in a straight line, and a third intersection portion P3 where the first main flow groove 31, the fourth communication groove 54, and the first communication groove 51 intersect in a cross shape is formed. Similarly, in the third main flow groove 33, a second communication groove 52 and a third communication groove 53 extending in the second direction Y are arranged in a straight line, and a third intersection portion P3 where the third main flow groove 33, the second communication groove 52, and the third communication groove 53 intersect in a cross shape is formed. Even in such a form, since the second main flow groove 32 and the fourth main flow groove 34 include the first intersection portion P1 and the second intersection portion P2, the transport function of the liquid working fluid 2 in the liquid flow path portion 30 can be improved.

[0120] In addition, in the above-described embodiment, an example in which a plurality of first intersection portions P1 and second intersection portions P2 are provided in each of the main flow grooves 31 to 34 and arranged alternately has been described. However, it is not limited to this. For example, if each of the main flow grooves 31 to 34 includes one first intersection portion P1 and one second intersection portion P2, the transport function of the working fluid 2 can be improved. Further, an example in which the first intersection portion P1 and the second intersection portion P2 are adjacent to each other in each of the main flow grooves 31 to 34 has been described, but it is not limited to this. For example, in each of the main flow grooves 31 to 34, between the first intersection portion P1 and the second intersection portion P2, the communication grooves 51 to 54 on both sides are arranged in a straight line, and an intersection portion (for example, P3 shown in FIG. 14) where the main flow grooves 31 to 34 and the communication grooves 51 to 54 intersect in a cross shape may be formed. Even in this case, the transport function of the liquid working fluid 2 in the liquid flow path portion 30 can be improved by the first intersection portion P1 and the second intersection portion P2.

[0121] In addition, in the above-described embodiment, an example in which the first to fourth main flow grooves 31 to 34 and the first to fourth connection grooves 51 to 54 are orthogonal to each other has been described. However, the present invention is not limited to this, and the first to fourth main flow grooves 31 to 34 and the first to fourth connection grooves 51 to 54 do not have to be orthogonal as long as they can intersect each other.

[0122] For example, as shown in FIG. 15, the directions in which the connection grooves 51 to 54 are aligned may be inclined with respect to the first direction X and the second direction Y, respectively. The inclination angle θ of the connection grooves 51 to 54 with respect to the first direction X in this case is arbitrary. In the example shown in FIG. 15, the flat plane shapes of the convex portions 41a to 44a are parallelograms. When such a shape is adopted for the rectangular vapor chamber 1, the four outer edges 1a and 1b (see FIG. 2) forming the outer contour of the vapor chamber 1 in the plane and the connection grooves 51 to 54 are no longer orthogonal. In this case, it is possible to prevent deformation so as to bend along the broken line extending in the second direction Y, and it is possible to prevent the grooves 31 to 34 and 51 to 54 of the liquid flow path portion 30 from being crushed.

[0123] In addition, the first to fourth main flow grooves 31 to 34 do not have to be formed linearly. For example, in FIG. 16, the main flow grooves 31 to 34 do not extend linearly but meander, and globally extend in the first direction X. More specifically, the pair of side walls 35 and 36 of the main flow groove 31 are formed such that the curved concave portions and the curved convex portions are alternately arranged and continuously and smoothly connected. When the main flow grooves 31 to 34 are formed as shown in FIG. 16, the contact area between the working fluid 2 and the convex portions 41a to 44a increases, and the cooling efficiency of the working fluid 2 can be improved.

[0124] In addition, in the above-described embodiment, an example in which the convex portions 41a to 44a are arranged in a staggered pattern in a rectangular shape over the entire fluid passage portion 30 has been described. However, the present invention is not limited to this, and at least a part of the convex portions 41a to 44a may be arranged in a shape as shown in FIG. 15 or FIG. 16 described above. Furthermore, at least two of the staggered arrangement shown in FIG. 6, the arrangement shown in FIG. 15, and the arrangement shown in FIG. 16 may be combined for the convex portions 41a to 44a.

[0125] In addition, in the above-described embodiment, an example in which the first convex portion 41a, the second convex portion 42a, the third convex portion 43a, and the fourth convex portion 44a have the same shape has been described. However, the present invention is not limited to this, and the first to fourth convex portions 41a to 44a may have different shapes from each other.

[0126] For example, as shown in FIG. 17, the lengths of the second convex portion 42a and the fourth convex portion 44a in the first direction X may be longer than those of the first convex portion 41a and the third convex portion 43a. In the form shown in FIG. 17, in the second main flow groove 32 and the fourth main flow groove 34, two first intersection portions P1 are interposed between the two second intersection portions P2. That is, the first intersection portion P1 and the second intersection portion P2 are not alternately arranged as shown in FIG. 6. Also, in the first main flow groove 31 and the third main flow groove 33, two second intersection portions P2 are interposed between the two first intersection portions P1, and the first intersection portion P1 and the second intersection portion P2 are not alternately arranged. Even in this case, the first intersection portion P1 and the second intersection portion P2 can improve the transport function of the liquid hydraulic fluid 2 in the fluid passage portion 30.

[0127] In addition, in the above-described embodiment, an example in which the upper channel wall portion 22 of the upper metal sheet 20 extends in an elongated shape along the first direction X of the vapor chamber 1 has been described. However, the present invention is not limited to this, and the shape of the upper channel wall portion 22 is arbitrary. For example, the upper channel wall portion 22 may be formed as a cylindrical boss. Even in this case, it is preferable that the upper channel wall portion 22 is arranged so as to overlap the lower channel wall portion 13 in a plan view, and the lower surface 22a of the upper channel wall portion 22 is brought into contact with the upper surface 13a of the lower channel wall portion 13.

[0128] In addition, in the above-described embodiment, an example in which the upper metal sheet 20 has the upper vapor channel recess 21 has been described. However, the present invention is not limited to this, and the upper metal sheet 20 may be formed in a flat plate shape as a whole and may not have the upper vapor channel recess 21. In this case, the lower surface 20a of the upper metal sheet 20 comes into contact with the upper surface 13a of the lower channel wall portion 13 as the second contact surface, and the mechanical strength of the vapor chamber 1 can be improved.

[0129] In addition, in the above-described embodiment, an example in which the lower metal sheet 10 has the lower vapor flow path recess 12 and the liquid flow path portion 30 has been described. However, the present invention is not limited to this. If the upper metal sheet 20 has the upper vapor flow path recess 21, the lower metal sheet 10 may not have the lower vapor flow path recess 12, and the liquid flow path portion 30 may be provided on the upper surface 10a of the lower metal sheet 10. In this case, as shown in FIG. 18, the region of the upper surface 10a where the liquid flow path portion 30 is formed may be formed not only in the region facing the upper flow path wall portion 22 but also in the region of the upper vapor flow path recess 21 excluding the upper flow path wall portion 22 among the regions facing the upper vapor flow path recess 21. In this case, the number of the main flow grooves 31 to 34 constituting the liquid flow path portion 30 can be increased, and the transport function of the liquid working fluid 2 can be improved. However, the region where the liquid flow path portion 30 is formed is not limited to the form shown in FIG. 18, and is arbitrary as long as the transport function of the liquid working fluid 2 can be ensured. Further, in the form shown in FIG. 18, the lower surface 22a (contact surface) of the upper flow path wall portion 22 of the upper metal sheet 20 is formed in a part of the region of the lower surface 20a of the upper metal sheet 20 in order to secure the vapor flow path, and the lower surface 22a of the upper flow path wall portion 22 comes into contact with a part of the region of the upper surface 10a of the lower metal sheet 10 where the liquid flow path portion 30 is formed.

[0130] In addition, in the above-described embodiment, an example in which the first to fourth main flow grooves 31 to 34 include the first intersection portion P1 and the second intersection portion P2 has been described. However, the present invention is not limited to this. Even if each of the main flow grooves 31 to 34 does not include the intersection portions P1 and P2, if the widths w1 of the first to fourth main flow grooves 31 to 34 are larger than the widths w2 of the first to fourth convex portions 41a to 44a, the ratio of the first to fourth main flow grooves 31 to 34 occupying the upper surface 13a of the lower flow path wall portion 13 can be increased. Also in this case, the transport function of the working fluid 2 can be improved, and the heat transport efficiency can be improved.

[0131] (Second Embodiment) Next, with reference to FIGS. 19 to 23, a vapor chamber, an electronic device, a metal sheet for a vapor chamber, and a method for manufacturing a vapor chamber according to a second embodiment of the present invention will be described.

[0132] In the second embodiment shown in FIGS. 19 to 23, the main difference is that the widths of the first to fourth communication grooves are larger than the widths of the first to fourth main flow grooves, and other configurations are substantially the same as those of the first embodiment shown in FIGS. 1 to 18. In FIGS. 19 to 23, the same parts as those of the first embodiment shown in FIGS. 1 to 18 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0133] As shown in FIG. 19, in the present embodiment, the widths w3' of the first to fourth communication grooves 51 to 54 are larger than the widths w1 of the first to fourth main flow grooves (more specifically, the widths of the first to fourth main flow groove main body portions 31a to 34a described later). The widths w3' of the communication grooves 51 to 54 may be, for example, 40 μm to 300 μm. In the present embodiment, as shown in FIGS. 20 and 21, an example in which the cross-sectional shapes of the respective main flow grooves 31 to 34 and the cross-sectional shapes of the respective communication grooves 51 to 54 are formed in a curved shape will be described. In this case, the widths of the grooves 31 to 34 and 51 to 54 are the widths of the grooves on the upper surface 13a of the lower flow path wall portion 13. Similarly, the widths of the convex portions 41a to 44a described later are the widths of the convex portions on the upper surface 13a.

[0134] Incidentally, also in the present embodiment, the lower surface 22a of the upper flow path wall portion 22 of the upper metal sheet 20 is formed in a flat shape. As a result, the first to fourth main flow grooves 31 to 34 of the liquid flow path portion 30 are covered with the flat lower surface 22a. In this case, as shown in FIG. 20, a pair of side walls 35 and 36 extending in the first direction X of the first to fourth main flow grooves 31 to 34 and the lower surface 22a of the upper flow path wall portion 22 can form two right-angled or acute-angled corners 37, and the capillary action at these two corners 37 can be enhanced. That is, even when the cross-sections of the first to fourth main flow grooves 31 to 34 are formed in a curved shape, the capillary action can be enhanced at the corners 37.

[0135] Similarly, the first to fourth communication grooves 51 to 54 of the liquid flow path portion 30 are covered by the flat lower surface 22a. In this case, as shown in FIG. 21, a pair of side walls 55, 56 extending in the second direction Y of the first to fourth communication grooves 51 to 54 and the lower surface 22a of the upper flow path wall portion 22 can form two right-angled or acute-angled corners 57, and the capillary action at these two corners 57 can be enhanced. That is, even when the cross-section of the first to fourth communication grooves 51 to 54 is formed in a curved shape, the capillary action can be enhanced at the corners 57.

[0136] Here, the liquid working fluid 2 condensed from the vapor enters the first to fourth main flow grooves 31 to 34 through the first to fourth communication grooves 51 to 54 as will be described later. Therefore, by enhancing the capillary action of the first to fourth communication grooves 51 to 54, the condensed liquid working fluid 2 can be smoothly introduced into the first to fourth main flow grooves 31 to 34. The condensed liquid working fluid 2 can smoothly enter not only the main flow groove 31 close to the vapor flow path recesses 12, 21 but also the first to fourth main flow grooves 31 to 34 far from the vapor flow path recesses 12, 21 due to the capillary action of the first to fourth communication grooves 51 to 54, and the transport function of the condensed liquid working fluid 2 can be improved. Also, by making the width w3' of the first to fourth communication grooves 51 larger than the width w1 of the first to fourth main flow grooves 31 to 34, the flow path resistance of the working fluid 2 in the first to fourth communication grooves 51 to 54 can be reduced, and in this regard as well, the condensed liquid working fluid 2 can be smoothly introduced into the first to fourth main flow grooves 31 to 34. Then, the working fluid 2 that has entered the first to fourth main flow grooves 31 to 34 can be smoothly transported toward the evaporation section 11 by the capillary action of the first to fourth main flow grooves 31 to 34. Therefore, the transport function of the liquid working fluid 2 can be improved as a whole for the liquid flow path portion 30.

[0137] In addition, both ends of the first to fourth convex portions 41a to 44a in the first direction X have a rounded shape in plan view. That is, each of the convex portions 41a to 44a is formed in a rectangular shape overall, but a rounded curved portion 45 is provided at its corner. As a result, the corners of each of the convex portions 41a to 44a are smoothly formed in a curved shape, and the flow path resistance of the liquid working fluid 2 is reduced. Note that at the right end and the left end of the convex portions 41a to 44a in FIG. 19, two curved portions 45 are provided respectively, and an example is shown in which a linear portion 46 is provided between these two curved portions 45. For this reason, the width w3' of the first to fourth communication grooves 51 to 54 is the distance between the linear portions 46 of the convex portions 41a to 44a adjacent to each other in the first direction X. As shown in FIG. 6, the same applies when the curved portion 45 is not formed on each of the convex portions 41a to 44a. However, the end shape of the convex portions 41a to 44a is not limited to this. For example, the entire end may be formed to curve (for example, in a semicircular shape) without providing the linear portion 46 at each of the right end and the left end. In this case, the width w3' of each of the communication grooves 51 to 54 is the minimum distance between the convex portions 41a to 44a adjacent to each other in the first direction X. Note that in FIG. 19, the curved portion 45 and the linear portion 46 are typically shown for the fourth convex portion 44a shown at the bottom most in order to clarify the drawing.

[0138] As shown in FIGS. 20 and 21, in the present embodiment, the depth h3' of the first to fourth communication grooves 51 to 54 is greater than the depth h1 of the first to fourth main flow grooves 31 to 34 (more specifically, the depth of the first to fourth main flow groove main body portions 31a to 34a described later). Here, as described above, when the cross-sectional shapes of the main flow grooves 31 to 34 and the cross-sectional shapes of the communication grooves 51 to 54 are formed in a curved shape, the depth of the grooves 31 to 34, 51 to 54 is the depth at the deepest position in the groove. The depth h3' of the first to fourth communication grooves 51 to 54 may be, for example, 10 μm to 250 μm.

[0139] In the present embodiment, as shown in FIG. 22, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the first to fourth main flow grooves 31 to 34 are deeper than the depth h1 of the portions of the main flow grooves 31 to 34 other than the first intersection portion P1 and other than the second intersection portion P2. That is, the first to fourth main flow grooves 31 to 34 further include first to fourth main flow groove main body portions 31a to 34a provided between the first intersection portion P1 and the second intersection portion P2. The first to fourth main flow groove main body portions 31a to 34a are portions located between adjacent convex portions 41a to 44a and are portions located between the adjacent first intersection portion P1 and the second intersection portion P2. The depths h1' of the first intersection portion P1 and the second intersection portion P2 are deeper than the depth h1 of the first to fourth main flow groove main body portions 31a to 34a. The depth h1' of the first intersection portion P1 is the depth at the deepest position in the first intersection portion P1, and the depth h1' of the second intersection portion P2 is the depth at the deepest position in the second intersection portion P2.

[0140] More specifically, as shown in FIGS. 19 and 22, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the first main flow groove 31 are deeper than the depth h1 of the portion (the first main flow groove main body portion 31a) between the fourth convex portion 44a and the first convex portion 41a of the first main flow groove 31. Similarly, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the second main flow groove 32 are deeper than the depth h1 of the portion (the second main flow groove main body portion 32a) between the first convex portion 41a and the second convex portion 42a of the second main flow groove 32. The depths h1' of the first intersection portion P1 and the second intersection portion P2 of the third main flow groove 33 are deeper than the depth h1 of the portion (the third main flow groove main body portion 33a) between the second convex portion 42a and the third convex portion 43a of the third main flow groove 33. The depths h1' of the first intersection portion P1 and the second intersection portion P2 of the fourth main flow groove 34 are deeper than the depth h1 of the portion (the fourth main flow groove main body portion 34a) between the third convex portion 43a and the fourth convex portion 44a of the fourth main flow groove 34.

[0141] Further, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the first to fourth main grooves 31 to 34 may be deeper than the depth h3' of the first to fourth connecting grooves 51 to 54. The depths h1' of such first intersection portion P1 and second intersection portion P2 may be, for example, 20 μm to 300 μm.

[0142] Also, as shown in FIG. 19, the first to fourth convex portions 41a to 44a are formed in a rectangular shape as a whole as described above, but are different from the planar shapes of the first to fourth convex portions 41a to 44a as shown in FIG. 6. That is, the first to fourth convex portions 41a to 44a include a pair of first to fourth convex portion end portions 41b to 44b provided on both sides in the first direction X, and first to fourth convex portion intermediate portions 41c to 44c provided between the pair of first to fourth convex portion end portions 41b to 44b. Among these, the width w4 of the first to fourth convex portion intermediate portions 41c to 44c is smaller than the width w2 of the first to fourth convex portion end portions 41b to 44b (corresponding to the width w2 of the first to fourth convex portions 41a to 44a described above).

[0143] More specifically, the width w4 of the middle portion 41c of the first convex portion is smaller than the width w2 of the end portion 41b of the first convex portion, and the walls of the first convex portion 41a (i.e., the side wall 36 of the first main flow groove 31 and the side wall 35 of the second main flow groove 32) are smoothly curved so as to be recessed toward the inside of the first convex portion 41a. For this reason, the width w4 of the middle portion 41c of the first convex portion is the minimum distance between the two walls. Similarly, the width w4 of the middle portion 42c of the second convex portion is smaller than the width w2 of the end portion 42b of the second convex portion, and the walls of the second convex portion 42a (i.e., the side wall 36 of the second main flow groove 32 and the side wall 35 of the third main flow groove 33) are smoothly curved so as to be recessed toward the inside of the second convex portion 42a. The width w4 of the middle portion 43c of the third convex portion is smaller than the width w2 of the end portion 43b of the third convex portion, and the walls of the third convex portion 43a (i.e., the side wall 36 of the third main flow groove 33 and the side wall 35 of the fourth main flow groove 34) are smoothly curved so as to be recessed toward the inside of the third convex portion 43a. The width w4 of the middle portion 44c of the fourth convex portion is smaller than the width w2 of the end portion 44b of the fourth convex portion, and the walls of the fourth convex portion 44a (i.e., the side wall 36 of the fourth main flow groove 34 and the side wall 35 of the first main flow groove 31) are smoothly curved so as to be recessed toward the inside of the fourth convex portion 44a. The widths w4 of the middle portions 41c to 44c of the first to fourth convex portions may be, for example, 15 μm to 175 μm.

[0144] As described above, the depths h3' of the first to fourth connection grooves 51 to 54 are deeper than the depth h1 of the first to fourth main flow groove main body portions 31a to 34a of the first to fourth main flow grooves 31 to 34, and the depths h1' of the first intersection portions P1 and the second intersection portions P2 of the first to fourth main flow grooves 31 to 34 are deeper than the depth h1 of the first to fourth main flow groove main body portions 31a to 34a. As a result, a buffer region Q deeper than the depth h1 of the first to fourth main flow groove main body portions 31a to 34a is formed in the region extending from the second intersection portion P2 to the first intersection portion P1 via the first to fourth connection grooves 51 to 54. This buffer region Q can store the liquid working fluid 2.

[0145] More specifically, for example, in the region extending from the second intersection P2 of the first main flow channel 31 to the first intersection P1 of the second main flow channel 32 via the first connection channel 51, a buffer region Q deeper than the depth h1 of the first main flow channel body 31a and the second main flow channel body 32a is formed. Usually, the liquid working fluid 2 is filled in each of the main flow channels 31 to 34 and each of the connection channels 51 to 54 of the liquid flow path portion 30. Therefore, since the depths (h1’ and h3’) of the buffer region Q are deeper than the depth h1 of the first to fourth main flow channel bodies 31a to 34a, it is possible to store a large amount of the working fluid 2 in the buffer region Q. As described above, since the working fluid 2 is filled in each of the main flow channels 31 to 34 and each of the connection channels 51 to 54, the working fluid 2 can be stored in the buffer region Q regardless of the attitude of the vapor chamber 1.

[0146] Similarly, in the region extending from the second intersection P2 of the second main flow channel 32 to the first intersection P1 of the third main flow channel 33 via the second connection channel 52, a buffer region Q deeper than the depth h1 of the second main flow channel body 32a and the third main flow channel body 33a is formed. In the region extending from the second intersection P2 of the third main flow channel 33 to the first intersection P1 of the fourth main flow channel 34 via the third connection channel 53, a buffer region Q deeper than the depth h1 of the third main flow channel body 33a and the fourth main flow channel body 34a is formed. In the region extending from the second intersection P2 of the fourth main flow channel 34 to the first intersection P1 of the first main flow channel 31 via the fourth connection channel 54, a buffer region Q deeper than the depth h1 of the fourth main flow channel body 34a and the first main flow channel body 31a is formed.

[0147] Note that a number of first intersection portions P1 and second intersection portions P2 are formed in each liquid flow path portion 30 of the vapor chamber 1. If the depth h1' of at least one of the intersection portions P1 and P2 is deeper than the depth h1 of the main flow groove main body portions 31a to 34a (or the depth h3' of the connection grooves 51 to 54), the storage performance of the working fluid 2 at the intersection portions P1 and P2 can be improved. Since this storage performance improves as the number of locations of the intersection portions P1 and P2 having a depth h1' deeper than the depth h1 of the main flow groove main body portions 31a to 34a increases, it is preferable that the depths h1' of all the intersection portions P1 and P2 have the same depth. However, it is obvious that the storage performance of the working fluid 2 can be improved even if the depth h1' of some of the intersection portions P1 and P2 is not deeper than the depth h1 of the main flow groove main body portions 31a to 34a due to manufacturing errors or the like. The same applies to the depth h3' of the connection grooves 51 to 54.

[0148] Here, a method for checking the widths, depths of the main flow grooves 31 to 34 and the widths, depths of the connection grooves 51 to 54 from the completed vapor chamber 1 will be described. Generally, the main flow grooves 31 to 34 and the connection grooves 51 to 54 are not visible from the outside of the vapor chamber 1. For this reason, a method of checking the widths and depths of the main flow grooves 31 to 34 and the connection grooves 51 to 54 from the cross-sectional shape obtained by cutting the completed vapor chamber 1 at a desired position can be mentioned.

[0149] Specifically, first, the vapor chamber 1 was cut into 10 mm square pieces with a wire saw to obtain samples. Subsequently, while degassing the samples under vacuum, they were resin-embedded so that resin would enter the vapor flow path recesses 12 and 21 and the liquid flow path portions 30 (main flow grooves 31 to 34 and connection grooves 51 to 54). Next, trimming was performed with a diamond knife so as to obtain a desired cross-section. At this time, using the diamond knife of a microtome (ultramicrotome manufactured by Leica Microsystems), trimming was performed up to a portion 40 μm away from the measurement target position. For example, assuming that the pitch of the connection grooves 51 to 54 is 200 μm, by cutting 160 μm from the connection grooves 51 to 54 adjacent to the connection grooves 51 to 54 that are the measurement targets, a portion 40 μm away from the connection grooves 51 to 54 that are the measurement targets can be specified. Next, by shaving the cut surface after trimming, a cut surface for observation was produced. At this time, using a cross-section polisher (manufactured by JOEL), the protrusion width was set to 40 μm, the voltage was set to 5 kV, and the time was set to 6 hours, and the cut surface was shaved by ion beam processing. Thereafter, the cut surface of the obtained sample was observed. At this time, using a scanning electron microscope (scanning electron microscope manufactured by Carl Zeiss), the voltage was set to 5 kV, the working distance was set to 3 mm, and the observation magnification was set to 500 times, and the cut surface was observed. In this way, the widths and depths of the main flow grooves 31 to 34 and the connection grooves 51 to 54 can be measured. Note that the observation magnification standard at the time of photography is Polaroid 545.

[0150] Incidentally, as described above, the widths w3' of the first to fourth connection grooves 51 to 54 are larger than the width w1 of the first to fourth main flow grooves 31 to 34. As a result, the buffer region Q is an area that opens wider than the first to fourth main flow groove main body portions 31a to 34a. For this reason, in the second half-etching process shown in FIG. 10, the etching liquid enters more into the buffer region Q than into the first to fourth main flow groove main body portions 31a to 34a. As a result, erosion by the etching liquid in the buffer region Q progresses, and the depth of the buffer region Q increases. Then, since the portions of the buffer region Q corresponding to the first intersection portion P1 and the second intersection portion P2 communicate with the first to fourth main flow groove main body portions 31a to 34a, the etching liquid can more easily enter than the first to fourth connection grooves 51 to 54. As a result, the depths h1' of the first intersection portion P1 and the second intersection portion P2 can be deeper than the depths h3' of the first to fourth connection grooves 51 to 54. In this way, a buffer region Q as shown in FIG. 22 is formed.

[0151] In addition, since a large amount of etching liquid enters the buffer region Q, erosion by the etching liquid progresses at the portions of the walls of the first to fourth convex portions 41a to 44a (the side walls 35 and 36 of the first to fourth main flow grooves 31 to 34) facing the first intersection portion P1 and the second intersection portion P2. As a result, the walls of the respective convex portions 41a to 44a are eroded so as to be gouged by the etching liquid, forming a smooth curved shape that is concave toward the inside of the respective convex portions 41a to 44a.

[0152] In the second half-etching step shown in FIG. 10, as described above, a second resist film is formed in a pattern on the upper surface 13a of the lower channel wall portion 13, and the etching liquid enters the resist opening of the second resist film to form the first to fourth main flow grooves 31 to 34 and the first to fourth connection grooves 51 to 54. Even when the resist opening is formed parallel to the first direction X and the second direction Y, since the widths w3' of the first to fourth connection grooves 51 to 54 are larger than the widths w1 of the first to fourth main flow grooves 31 to 34, the etching liquid can easily enter the buffer region Q. Therefore, the buffer region Q as described above can be formed.

[0153] In the vapor chamber 1 according to this embodiment, the vapor of the working fluid 2 diffused to the peripheral portion of the vapor chamber 1 is cooled and condensed. The condensed working fluid 2 in the liquid state enters the main flow channel 31 through the first to fourth connection grooves 51 to 54. Here, as described above, since the widths w3' of the first to fourth connection grooves 51 to 54 are larger than the width w1 of the first to fourth main flow channels 31 to 34, the flow path resistance of the working fluid 2 in each connection groove 51 to 54 is small. Therefore, the liquid working fluid 2 adhering to the wall surfaces of the vapor flow path recesses 12 and 21 smoothly enters the main flow channels 31 to 34 through the connection grooves 51 to 54. Then, the main flow channels 31 to 34 and the connection grooves 51 to 54 are filled with the liquid working fluid 2.

[0154] When the working fluid 2 filled in the main flow channels 31 to 34 is transported toward the evaporation section 11, a part of the working fluid 2 travels toward the evaporation section 11 while passing through the first intersection P1 and the second intersection P2. At the first intersection P1 and the second intersection P2, the working fluid 2 mainly obtains a driving force toward the evaporation section 11 by capillary action at the corner 37 formed by the side walls 35 and 36 of the first to fourth main flow channels 31 to 34 and the lower surface 22a of the upper flow path wall portion 22.

[0155] On the other hand, a part of the working fluid 2 traveling toward the evaporation section 11 is drawn into and stored in the buffer region Q formed by the first intersection P1 or the second intersection P2.

[0156] Here, when dry-out occurs in the first to fourth main flow channel main body portions 31a to 34a, the working fluid 2 stored in the buffer region Q moves toward the dry-out generation portion. More specifically, for example, when dry-out occurs in the first main flow channel main body portion 31a, the working fluid 2 moves from the buffer region Q closest to the dry-out generation portion to the dry-out generation portion by capillary action of the first main flow channel main body portion 31a. As a result, the dry-out generation portion is filled with the working fluid 2 and the dry-out is eliminated.

[0157] Also, in the first to fourth main flow channel body portions 31a to 34a, when bubbles due to its vapor are generated in the liquid working fluid 2, the bubbles are drawn into and held in the buffer region Q on the downstream side (the side of the evaporation section 11). Since the depth of the buffer region Q is deeper than the depth h1 of the first to fourth main flow channel body portions 31a to 34a, the bubbles drawn into the buffer region Q are suppressed from moving from the buffer region Q to the main flow channel body portions 31a to 34a. For this reason, the buffer region Q can capture the bubbles generated in the main flow channel body portions 31a to 34a, and it can be suppressed that the flow of the working fluid 2 to the evaporation section 11 is obstructed by the bubbles.

[0158] As described above, according to the present embodiment, the widths w3' of the first to fourth connection grooves 51 to 54 are larger than the widths w1 of the first to fourth main flow channels 31 to 34. Thereby, the flow path resistance of the working fluid 2 in each of the connection grooves 51 to 54 can be reduced. For this reason, the liquid working fluid 2 condensed from the vapor can smoothly enter each of the main flow channels 31 to 34. That is, not only the main flow channels 31 to 34 on the side closer to the vapor flow path recesses 12 and 21 but also the main flow channels 31 to 34 on the side farther from the vapor flow path recesses 12 and 21 can be smoothly entered, and the transport function of the condensed liquid working fluid 2 can be improved. As a result, the transport function of the liquid working fluid 2 can be improved, and the heat transport efficiency can be improved.

[0159] Further, according to the present embodiment, the depths h3' of the first to fourth communication grooves 51 to 54 are deeper than the depth h1 of the first to fourth main flow grooves 31 to 34. As a result, a buffer region Q for storing the working fluid 2 can be formed in each of the communication grooves 51 to 54. Therefore, when dry-out occurs in the main flow grooves 31 to 34, the working fluid 2 stored in the buffer region Q can be moved to the dry-out occurrence portion. For this reason, dry-out can be eliminated, and the transport function of the working fluid 2 in each of the main flow grooves 31 to 34 can be restored. Further, when bubbles are generated in the main flow grooves 31 to 34, the bubbles can be drawn into and captured by the buffer region Q. Also in this regard, the transport function of the working fluid 2 in each of the main flow grooves 31 to 34 can be restored.

[0160] Further, according to the present embodiment, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the first to fourth main flow grooves 31 to 34 are deeper than the depth h1 of the first to fourth main flow groove main body portions 31a to 34a. As a result, the buffer region Q can be extended to the first intersection portion P1 and the second intersection portion P2. Therefore, the storage amount of the working fluid 2 in the buffer region Q can be increased, and it is easier to further eliminate dry-out.

[0161] Further, according to the present embodiment, the depths h1' of the first intersection portion P1 and the second intersection portion P2 of the first to fourth main flow grooves 31 to 34 are deeper than the depths h3' of the first to fourth communication grooves 51 to 54. As a result, the depth of the buffer region Q can be increased on the side closer to the dry-out occurrence portion in the buffer region Q. Therefore, the stored working fluid 2 can be smoothly moved to the dry-out occurrence portion, and it is easier to further eliminate dry-out.

[0162] Further, according to the present embodiment, the widths w4 of the intermediate portions 41c to 44c of the first to fourth convex portions 41a to 44a are smaller than the widths w2 of the end portions 41b to 44b of the first to fourth convex portions. As a result, the planar areas of the first intersection portion P1 and the second intersection portion P2 can be increased. Therefore, the storage amount of the working fluid 2 in the buffer region Q can be increased, and it is easier to further eliminate dry-out.

[0163] Further, according to the present embodiment, rounded curved portions 45 are provided at the corners of the respective convex portions 41a to 44a. As a result, the corners of the respective convex portions 41a to 44a can be formed into a smooth curved shape, and the flow path resistance of the liquid working fluid 2 can be reduced.

[0164] (Third Embodiment) Next, with reference to FIGS. 23 to 25, a vapor chamber, a metal sheet for vapor chamber, and a method for manufacturing a vapor chamber according to the third embodiment of the present invention will be described.

[0165] In the third embodiment shown in FIGS. 23 to 25, the main difference is that main flow groove convex portions protrude into the first to fourth main flow grooves, and communication groove convex portions protrude into the first to fourth communication grooves. Other configurations are substantially the same as those of the second embodiment shown in FIGS. 19 to 22. In FIGS. 23 to 25, the same parts as those of the second embodiment shown in FIGS. 19 to 22 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0166] As shown in FIG. 23, in the present embodiment, the upper metal sheet 20 has a plurality of main flow groove convex portions 27 provided on the lower surface 20a. Each main flow groove convex portion 27 protrudes into the corresponding main flow grooves 31 to 34 of the first to fourth main flow grooves 31 to 34 of the lower metal sheet 10 from the lower surface 20a. The lower end of the main flow groove convex portion 27 is spaced apart from the bottom of the main flow grooves 31 to 34, and a flow path for the working fluid 2 is ensured. Further, each main flow groove convex portion 27 is formed to extend in the first direction X along the corresponding main flow grooves 31 to 34.

[0167] The cross-section of the main flow groove convex portion 27 is formed in a curved shape. Also, the side edges of the main flow groove convex portion 27 are in contact with or close to the side walls 35, 36 of the first to fourth main flow grooves 31 to 34. As a result, the corner portion 37 formed by the side walls 35, 36 of the first to fourth main flow grooves 31 to 34 and the lower surface 22a of the upper flow path wall portion 22 is formed in a wedge shape (or acute angle shape). In this way, the flow path cross-section (the flow path cross-section in the second direction Y) defined by the main flow grooves 31 to 34 and the main flow groove convex portion 27 is formed in a crescent shape as shown in FIG. 23.

[0168] Also, as shown in FIGS. 24 and 25, in the present embodiment, the upper metal sheet 20 has a plurality of connection groove convex portions 28 provided on the lower surface 20a. Each connection groove convex portion 28 protrudes from the lower surface 20a into the corresponding connection grooves 51 to 54 among the first to fourth connection grooves 51 to 54 of the lower metal sheet 10. The lower end of the connection groove convex portion 28 is spaced apart from the bottom of the connection grooves 51 to 54, and a flow path for the working fluid 2 is ensured. Also, each connection groove convex portion 28 is formed to extend in the second direction Y along the corresponding connection grooves 51 to 54. At the first intersection portion P1 and the second intersection portion P2 of the first to fourth main flow grooves 31 to 34, the above-described main flow groove convex portion 27 and the connection groove convex portion 28 intersect in a T shape.

[0169] The cross-section of the connection groove convex portion 28 is formed in a curved shape, similar to the main flow groove convex portion 27. Further, the side edges of the connection groove convex portion 28 are in contact with, or close to, a pair of side walls 55, 56 (see FIG. 19) extending in the second direction Y of the first to fourth connection grooves 51 to 54. As a result, a corner portion 57 formed by the side walls 55, 56 of the first to fourth connection grooves 51 to 54 and the lower surface 22a of the upper flow path wall portion 22 is formed in a wedge shape (or an acute angle shape). In this way, the flow path cross-section (the flow path cross-section in the first direction X) defined by the connection grooves 51 to 54 and the connection groove convex portion 28 is formed in a crescent shape as shown in FIG. 24. Further, the flow path cross-section in the second direction Y is formed such that the flow path cross-sections of the first to fourth connection grooves 51 to 54 in the second direction Y are interposed between the flow path cross-sections of the main flow grooves 31 to 34 shown in FIG. 23. Therefore, as shown in FIG. 25, it is formed in an elongated crescent shape. In FIG. 19, for the sake of clarity of the drawing, only the side walls of the third connection groove 53 are labeled with reference numerals 55, 56. The side walls 55, 56 correspond to the above-described linear portions 46 of the convex portions 41a to 44a.

[0170] The main flow groove convex portion 27 and the connection groove convex portion 28 can be formed, for example, by half-etching the upper metal sheet 20 to form the upper flow path wall portion 22 and the like, and then press-working the upper metal sheet 20 alone. Alternatively, in the permanent joining process shown in FIG. 12, the main flow groove convex portion 27 and the connection groove convex portion 28 can be formed by increasing the pressing force applied to the lower metal sheet 10 and the upper metal sheet 20. That is, by increasing the pressing force, a part of the upper flow path wall portion 22 of the upper metal sheet 20 can be made to enter into the first to fourth main flow grooves 31 to 34 and the first to fourth connection grooves 51 to 54, thereby forming the main flow groove convex portion 27 and the connection groove convex portion 28 having a curved cross-section.

[0171] Thus, according to this embodiment, the main flow groove protrusions 27 protrude from the lower surface 20a of the upper metal sheet 20 into the corresponding main flow grooves 31 to 34 among the first to fourth main flow grooves 31 to 34 of the lower metal sheet 10. As a result, the corner 37 formed by the side walls 35, 36 of the first to fourth main flow grooves 31 to 34 and the lower surface 22a of the upper flow path wall portion 22 can be made into a minute space defined by the side walls 35, 36 of the first to fourth main flow grooves 31 to 34 and the main flow groove protrusions 27. Therefore, the capillary action at the corner 37 can be enhanced. As a result, the transport function of the liquid working fluid 2 in each of the main flow grooves 31 to 34 can be improved, and the heat transport efficiency can be improved. In particular, even when the first intersection P1 and the second intersection P2 of each of the main flow grooves 31 to 34 are configured as a buffer region Q as shown in FIG. 19, a high propulsive force toward the evaporation section 11 can be imparted to the working fluid 2 at the first intersection P1 and the second intersection P2 by the capillary action of the main flow groove protrusions 27, and the transport function of the working fluid 2 can be effectively improved.

[0172] Also, according to this embodiment, the cross section of the main flow groove protrusion 27 is formed in a curved shape. As a result, the corner 37 can be shaped like the end of a crescent shape. Therefore, the capillary action at the corner 37 can be further enhanced.

[0173] Further, according to this embodiment, the communication groove protrusions 28 protrude from the lower surface 20a of the upper metal sheet 20 into the corresponding communication grooves 51 to 54 among the first to fourth communication grooves 51 to 54 of the lower metal sheet 10. As a result, the corner 57 formed by the side walls 55, 56 of the first to fourth communication grooves 51 to 54 and the lower surface 22a of the upper flow path wall portion 22 can be made into a minute space defined by the side walls 55, 56 of the first to fourth communication grooves 51 to 54 and the communication groove protrusions 28. Therefore, the capillary action at the corner 57 can be enhanced.

[0174] Here, as described above, the liquid working fluid 2 condensed from the vapor enters the first to fourth main flow grooves 31 to 34 through the first to fourth communication grooves 51 to 54. Therefore, by enhancing the capillary action of the first to fourth communication grooves 51 to 54, the condensed liquid working fluid 2 can be smoothly introduced into the first to fourth main flow grooves 31 to 34. The condensed liquid working fluid 2 can smoothly enter not only the main flow grooves 31 to 34 on the side closer to the vapor flow path recesses 12 and 21 but also the main flow grooves 31 to 34 on the side farther from the vapor flow path recesses 12 and 21 due to the capillary action of the first to fourth communication grooves 51 to 54, and the transport function of the condensed liquid working fluid 2 can be improved. Also, by making the width w3' of the first to fourth communication grooves 51 to 54 larger than the width w1 of the first to fourth main flow grooves 31 to 34, the flow path resistance of the working fluid 2 in the first to fourth communication grooves 51 to 54 can be reduced. Also in this regard, the condensed liquid working fluid 2 can be smoothly introduced into the first to fourth main flow grooves 31 to 34. Then, the working fluid 2 that has entered the first to fourth main flow grooves 31 to 34 can be smoothly transported toward the evaporation section 11 by the capillary action of the first to fourth main flow grooves 31 to 34. Therefore, the transport function of the liquid working fluid 2 can be improved for the entire liquid flow path section 30. Also, as described above, by enhancing the capillary action of the first to fourth communication grooves 51 to 54, when dryout occurs, the working fluid 2 can be made to flow back and forth between the first to fourth main flow grooves 31 to 34 by the capillary action of the first to fourth communication grooves 51 to 54, and the dryout can be eliminated.

[0175] Further, according to the present embodiment, the cross section of the communication groove convex portion 28 is formed in a curved shape. As a result, the corner portion 57 can be shaped like the end portion of a crescent moon. Therefore, the capillary action at the corner portion 57 can be further enhanced.

[0176] In the above-described embodiment, an example in which the cross-sections of the first to fourth main flow grooves 31 to 34 and the cross-sections of the first to fourth connecting grooves 51 to 54 are formed in a curved shape has been described. However, the present invention is not limited to this, and the cross-sections of the first to fourth main flow grooves 31 to 34 and the cross-sections of the first to fourth connecting grooves 51 to 54 may be formed in a rectangular shape as shown in FIG. 7. Even in this case, the capillary action at the corners 37 and 57 can be enhanced, and the liquid working fluid 2 transport function in the first to fourth main flow grooves 31 to 34 and the first to fourth connecting grooves 51 to 54 can be improved. In order to make the cross-section rectangular, the main flow grooves 31 to 34 and the connecting grooves 51 to 54 are preferably formed by press working or cutting working.

[0177] Also, in the above-described embodiment, an example in which the width w3' of the first to fourth connecting grooves 51 to 54 is larger than the width w1 of the first to fourth main flow grooves 31 to 34 has been described. However, the present invention is not limited to this, and the width w3' of each connecting groove 51 to 54 may not be larger than the width w1 of each main flow groove 31 to 34 as shown in FIG. 6. That is, the effect of enhancing the capillary action of the first to fourth main flow grooves 31 to 34 by the main flow groove convex portions 27 and enhancing the transport function of the liquid working fluid 2 in the main flow grooves 31 to 34 can be exerted regardless of the size relationship between the width w3' of the connecting grooves 51 to 54 and the width w1 of the main flow grooves 31 to 34. Similarly, the effect of enhancing the capillary action of the first to fourth connecting grooves 51 to 54 by the connecting groove convex portions 28 and enhancing the transport function of the condensed liquid working fluid 2 can also be exerted regardless of the size relationship between the width w3' of the connecting grooves 51 to 54 and the width w1 of the main flow grooves 31 to 34.

[0178] The present invention is not limited to the above-described embodiments and modifications as they are. In the implementation stage, the components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in the above-described embodiments and modifications. Some components may be deleted from all the components shown in the embodiments and modifications. Further, in each of the above-described embodiments and modifications, the configuration of the lower metal sheet 10 and the configuration of the upper metal sheet 20 may be interchanged.

Claims

1. A vapor chamber filled with a working fluid, a first metal sheet, a second metal sheet provided on the first metal sheet, a vapor flow path portion through which the vapor of the working fluid passes, and a liquid flow path portion through which the liquid working fluid passes, wherein the liquid flow path portion is provided on the surface of the first metal sheet on the side of the second metal sheet, the liquid flow path portion includes a first main flow groove extending in a first direction through which the liquid working fluid passes, a first convex portion row including a plurality of first convex portions provided adjacent to the first main flow groove and arranged in the first direction, and a second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove, the second communication groove communicates with the first main flow groove, the first main flow groove includes an intersection portion where the second communication groove faces the first convex portion, a vapor chamber, wherein the width of an intermediate portion of at least one of the first convex portions facing the intersection portion is smaller than the width of an end portion of the first convex portion not facing the intersection portion.

2. The first convex portions are arranged in the first direction via a first communication groove, the liquid flow path portion includes a second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove, a second main flow groove extending in the first direction through which the liquid working fluid passes, and a third convex portion row including a plurality of third convex portions arranged in the first direction via a third communication groove, the first convex portion row, the first main flow groove, the second convex portion row, the second main flow groove, and the third convex portion row are arranged in this order in a second direction orthogonal to the first direction, the first communication groove faces the second convex portion via the first main flow groove, the second communication groove faces the first convex portion via the first main flow groove, the vapor chamber according to claim 1, wherein the third communication groove faces the second communication groove via the second main flow groove.

3. The first convex portions are arranged in the first direction via a first communication groove, the vapor chamber according to claim 1, wherein the first communication groove extends in a direction inclined with respect to the first direction.

4. The first main flow groove extends while meandering in the first direction, the vapor chamber according to claim 1.

5. a housing, a device housed in the housing, and an electronic device comprising the vapor chamber according to any one of claims 1 to 4 in thermal contact with the device.

6. A vapor chamber metal sheet for a vapor chamber having a vapor flow path portion through which vapor of the working fluid is passed and a liquid flow path portion through which the liquid working fluid is passed, the vapor chamber metal sheet being sealed with the working fluid, a first surface, and a second surface provided on the side opposite to the first surface, wherein the liquid flow path portion is provided on the first surface, the liquid flow path portion includes a first main flow groove extending in a first direction through which the liquid working fluid passes, a first convex portion row including a plurality of first convex portions provided adjacent to the first main flow groove and arranged in the first direction, and a second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove, the second communication groove communicates with the first main flow groove, the first main flow groove includes an intersection portion where the second communication groove faces the first convex portion, a vapor chamber metal sheet, wherein the width of an intermediate portion of at least one of the first convex portions facing the intersection portion is smaller than the width of an end portion of the first convex portion not facing the intersection portion. **Claim 7**: The first convex portions are arranged in the first direction via a first communication groove, the liquid flow path portion includes a second convex portion row including a plurality of second convex portions arranged in the first direction via a second communication groove, a second main flow groove extending in the first direction through which the liquid working fluid passes, and a third convex portion row including a plurality of third convex portions arranged in the first direction via a third communication groove, the first convex portion row, the first main flow groove, the second convex portion row, the second main flow groove, and the third convex portion row are arranged in this order in a second direction orthogonal to the first direction, the first communication groove faces the second convex portion via the first main flow groove, the second communication groove faces the first convex portion via the first main flow groove, the vapor chamber metal sheet according to claim 6, wherein the third communication groove faces the second communication groove via the second main flow groove. **Claim 8**: The first convex portions are arranged in the first direction via a first communication groove, the vapor chamber metal sheet according to claim 6, wherein the first communication groove extends in a direction inclined with respect to the first direction. **Claim 9**: The first main flow groove extends while meandering in the first direction, the vapor chamber metal sheet according to claim 6.

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