Vapor chambers, electronic devices

Abstract

To provide a vapor chamber in which an optical identification structure acting on a front and rear surfaces as an ID is formed and which improves reading property of the optical identification structure when it is read by optical means such as visual observation, a camera, a scanner or a reader to enable stable quality management, thereby providing a vapor chamber with preferable quality.SOLUTION: A flat-plate-like vapor chamber including a flow channel for a fluid for transporting heat therein includes an optical identification structure acting as an ID and formed on a smooth surface straddling between part having an internal space of a surface of the vapor chamber and part free from any internal space.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a vapor chamber having an internal flow path for a fluid responsible for heat transport. [Background technology]

[0002] Devices that generate heat, such as central processing units (CPUs) used in mobile devices such as mobile terminals and tablet terminals, are cooled by heat dissipation members such as heat pipes (see, for example, Patent Document 1). In recent years, there has been a demand for thinner heat dissipation members in order to make mobile terminals thinner, and vapor chambers that can be made thinner than heat pipes have been developed.

[0003] A vapor chamber is a device that applies the heat transport mechanism of a heat pipe to a flat plate-shaped component (metal sheet). In other words, in a vapor chamber, a fluid that transports heat is sealed between two flat plate-shaped components that are opposed to each other and joined together, and this fluid circulates while undergoing a phase change, transporting and diffusing the heat in the heat source to cool the heat source.

[0004] For example, there is a form in which a vapor flow path and a condensate flow path are provided between the opposing flat plate-like members of a vapor chamber, and a fluid responsible for heat transport is sealed in these. When the vapor chamber is placed in a heat source, the fluid responsible for heat transport near the heat source receives heat from the heat source and evaporates, becoming a gas (steam) that travels through the vapor flow path. This allows the heat from the heat source to be smoothly transported to a position away from the heat source, resulting in the heat source being cooled. The gaseous fluid that transports heat from the heat source moves to a position away from the heat source, where it is cooled and condensed as heat is absorbed by the surroundings, changing its phase to a liquid state. The liquid fluid that has changed phase passes through the condensate flow path, returns to the position of the heat source, receives heat from the heat source again, and evaporates, changing to a gaseous state. By circulating as described above, the heat generated from the heat source is transported to a location away from the heat source, and the heat source is cooled.

[0005] The joining between the opposing plate-like members is often performed by diffusion bonding (see, for example, Patent Document 1), brazing (see, for example, Patent Document 2), or welding (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-205693 A [Patent Document 2] JP 2007-212028 A [Patent Document 3] JP 2012-132582 A Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, after joining the flat plate-shaped members, an optical identification structure acting as an ID may be formed on the front or back surface of each of the plate-shaped vapor chambers in the process of being formed. The ID information of the optical identification structure formed for each of the vapor chambers in the process of being formed is different from one another. This is because it is necessary to clearly distinguish each of the vapor chambers in the process of being formed in order to associate them with lot management, air pressure conditions when injecting a fluid responsible for heat transport, and inspection results for the amount of the fluid injected.

[0008] The optical identification structure is formed by inkjet printing or laser printing or engraving on the front or back surface of the vapor chamber during its formation, and the optical identification structure thus formed is often read by optical means such as visual inspection, a camera, a scanner, or a reader.

[0009] 12(a) shows a top view of an example in which an optical identification structure 901 acting as an ID is formed as a QR code (registered trademark) on the upper surface 920b of the upper metal sheet 920. A QR code, which is the optical identification structure 901, is formed for each vapor chamber 900, and the ID information possessed by each optical identification structure 901 (QR code) is individually different. This makes it possible to identify each vapor chamber 900 individually.

[0010] When the optical identification structure 901 is a QR code, it is usually preferable that the length of one side is 1 mm or more. This is because if each cell inside the QR code is a certain size or more, it is less susceptible to variations in the formation of the optical identification structure 901 that forms the QR code and the surface state of the upper surface 920b of the upper metal sheet 920 or the lower surface 910b of the lower metal sheet 910 on which it is formed, and more stable reading is possible.

[0011] If the optical identification structure 901 can be accurately read by visual inspection, a camera, a scanner, a reader, or other optical means, the ID information held by the optical identification structure 901 can reliably and easily associate the pressure conditions when injecting the fluid responsible for heat transport, the inspection results for the amount of the fluid injected, or the functional inspection results after sealing with each vapor chamber 900, or perform lot management. This prevents the outflow of defective products, enabling stable quality management and providing vapor chambers 900 of good quality. Even in electronic devices equipped with such vapor chambers 900, poor heat dissipation is suppressed, so that defects in the electronic devices can be suppressed. In addition, the position of the optical identification structure 901 makes it easy to distinguish the front and back or the top and bottom of the vapor chamber 900, facilitating process management.

[0012] As described above, when reading the optical identification structure 901 by optical means such as visual inspection, a camera, a scanner, or a reader, a problem may arise in that it becomes difficult to read the optical identification structure 901 due to the relationship between the optical identification structure 901 and the surface of the background member. The main cause of this is that the shape of the internal sealed space on the upper surface 920b of the upper metal sheet 920 on which the optical identification structure 901 is formed, or on the lower surface 910b of the lower metal sheet 910, forms a pattern that hinders reading by the optical means.

[0013] As described above, when the optical identification structure 901 is a QR code, the length of one side is usually 1 mm or more. Therefore, as shown in Fig. 12(a), the optical identification structure 901 does not fit only in the upper vapor passage recess 922 or only in the upper passage wall 923 in a plan view, but straddles the boundary between the upper vapor passage recess 922 and the upper passage wall 923, or the boundary between the upper vapor passage recess 922 and the upper peripheral wall 924, i.e., the contour of the upper vapor passage recess 922, or the contour is in the immediate vicinity of the optical identification structure 901. Fig. 12(b) shows a partial cross-sectional conceptual diagram of the vapor chamber 900 (upper metal sheet 920) cut in the short direction in the portion of the upper metal sheet 920 where the optical identification structure 901 acting as an ID is formed. Fig. 12(b) is a conceptual cross-sectional view, and therefore differs from the top view of Fig. 12(a) in the positions of the optical identification structure 901 and the upper steam flow path recess 922. As conceptually shown in Fig. 12(b), whether or not the upper steam flow path recess 922 is formed affects the upper surface 920b of the upper metal sheet 920. When reading the optical identification structure 901, the outline of the upper steam flow path recess 922 exists within the reading area, and this outline impedes reading by the optical means described above.

[0014] That is, as described above, the vapor chamber 900 is formed by bonding opposing flat plate-like members, and diffusion bonding may be used for the bonding. Diffusion bonding involves bonding the flat plate-like members together and applying pressure and heat, but in the vapor chamber in the process of being formed after diffusion bonding, the shape of the internal sealed space may form a pattern on the front or back surface of the vapor chamber, which may hinder reading by the optical means. The flat plate-like member has a groove that serves as a passage for the sealed space, i.e., the fluid that transports heat, formed therein, and the shape of the groove (presence or absence of the groove) formed on the inside of the flat plate-like member (the bonding surface side, the side opposite the front or back surface of the vapor chamber in the process of being formed) may also form a pattern on the opposite surface, i.e., the front or back surface of the vapor chamber in the process of being formed, which may hinder reading by the optical means. It is presumed that the influence of the shape of the groove (presence or absence of the groove) in the flat plate-like member extends to the opposite surface because the plate thickness of the flat plate-like member is very thin, especially in the portion where the groove is formed, and the degree of minute deformation of the flat plate-like member due to pressure during diffusion bonding is slightly different between the portion where the groove is formed and the portion where the groove is not formed. Brazing is also sometimes used for joining, but similar problems can occur, although the temperature and pressure are different.

[0015] In view of the above, the object of the present invention is to provide a vapor chamber of good quality by enabling stable quality control by improving the readability of the optical identification structure formed on the front or back surface of the vapor chamber, which acts as an ID, when the optical identification structure is read by optical means such as visual inspection, a camera, a scanner, or a reader. [Means for solving the problem]

[0016] The present invention is a flat vapor chamber having an internal flow path for a fluid responsible for heat transport, which, in a planar view, has a flow path region in which the flow path is formed and a peripheral region surrounding the flow path region, and an optical identification structure that acts as an ID is formed in the peripheral region.

[0017] In the above-mentioned invention, the optical identification structure acting as an ID may be formed via a base layer.

[0018] The present invention is a flat vapor chamber having an internal flow path for a fluid responsible for heat transport, in which an optical identification structure acting as an ID is formed via a base layer.

[0019] The present invention is a flat vapor chamber having an internal flow path for a fluid responsible for heat transport, in which an optical identification structure acting as an ID is formed on a smooth surface having a maximum height roughness Rz of 1 μm or less.

[0020] The present invention is a flat vapor chamber having an internal flow path for a fluid responsible for heat transport, in which an optical identification structure acting as an ID is formed on a smooth surface with a height difference of 30 μm or less between the parts with internal space and the parts without internal space.

[0021] The present invention is a method for manufacturing a flat vapor chamber having an internal flow path for a fluid responsible for heat transport and an optical identification structure that acts as an ID, the method for manufacturing a vapor chamber comprising, in order, a step of polishing a portion where the optical identification structure that acts as an ID is to be formed, and a step of forming the optical identification structure that acts as the ID in the polished portion.

[0022] In the above invention, it is more preferable that the method for manufacturing a vapor chamber is such that the step of polishing the portion forming the optical identification structure acting as the ID is a step of polishing the portion so that the maximum height roughness Rz is 1 μm or less.

[0023] In the above invention, it is more preferable that the method for manufacturing a vapor chamber is such that the step of polishing the portion forming the optical identification structure acting as an ID is a step of polishing so that the difference in height between the portion with internal space and the portion without internal space is 30 μm or less. Effect of the Invention

[0024] According to the present invention, in a vapor chamber having an optical identification structure formed on the front or back surface that acts as an ID, the readability of the optical identification structure when read by optical means such as visual inspection, a camera, a scanner, or a reader is improved, enabling stable management and thereby providing a vapor chamber of good quality. [Brief description of the drawings]

[0025] [Figure 1] 1A and 1B are a top view and a partial cross-sectional conceptual diagram showing a vapor chamber according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is a top view for explaining the internal structure of the vapor chamber shown in FIG. 1 . [Diagram 3] Cross-sectional view of the vapor chamber taken along line AA in Figure 2. [Figure 4] Top view of the lower metal sheet of Figure 2. [Diagram 5] 3 is a bottom view of the upper metal sheet of FIG. 2. [Figure 6] 5A and 5B are a top view and a partial cross-sectional conceptual diagram showing a vapor chamber according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a top view showing a vapor chamber according to another example of the second embodiment of the present invention. [Figure 8] 13A and 13B are a top view and a partial cross-sectional conceptual diagram showing a vapor chamber according to a third embodiment of the present invention. [Figure 9] 13A and 13B are a top view and a partial cross-sectional conceptual diagram showing a vapor chamber according to a fourth embodiment of the present invention. [Figure 10] FIG. 13 is a top view showing a vapor chamber according to another example of the fourth embodiment of the present invention. [Figure 11] 13A to 13C are conceptual diagrams, partially in cross section, showing a method for manufacturing a vapor chamber according to a fourth embodiment of the present invention. [Figure 12] (a) Top view and (b) partial cross-sectional schematic diagram showing a conventional vapor chamber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the scale and the aspect ratio are appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding.

[0027] (First embodiment) Fig. 1(a) shows a plan view (top view) of a vapor chamber 100 in a first embodiment of the present invention as seen from the upper side (surface). In the vapor chamber 100 in Fig. 1(a), an optical identification structure 101 acting as an ID is formed on the upper surface 120b of an upper metal sheet 120. In a plan view, the vapor chamber 100 has a flow path region in which a flow path, i.e., an upper vapor flow path recess 122 (lower vapor flow path recess 112), is formed, and a peripheral region surrounding the flow path region, i.e., a region in which an upper peripheral wall 124 (lower peripheral wall 114) is present, and in the first embodiment, the optical identification structure 101 is formed in the peripheral region (region in which the upper peripheral wall 124 is present).

[0028] In the case where the optical identification structure 101 is formed in the first embodiment shown in Fig. 1(a), the entire optical identification structure 101 is contained within the area (peripheral area) where the upper peripheral wall 124 exists. Fig. 1(b) shows a partial cross-sectional conceptual diagram of the vapor chamber 100 (upper metal sheet 120) cut in the short direction in the portion of the upper metal sheet 120 where the optical identification structure 101 acting as an ID is formed. Fig. 1(b) is a conceptual cross-sectional view, and therefore the positions of the optical identification structure 101 and the upper vapor flow path recess 122 are different from those in the top view of Fig. 1(a). Since the entire optical identification structure 101 is contained within the area where the upper peripheral wall 124 exists (the peripheral area, i.e., the area where the upper steam flow path recess 122 is not formed), there is almost no influence caused by the influence of the formation of the upper steam flow path recess 122 extending to the upper surface 120b of the upper metal sheet 120, as conceptually shown in Figure 1(b).

[0029] That is, the above-mentioned problem of the conventional technology, in which the contour shape of the upper vapor flow path recess 122 adversely affects the reading of the optical identification structure 101 as a background pattern, can be significantly suppressed. Therefore, the readability of the optical identification structure 101 is improved, and defective vapor chambers 100 can be identified reliably. This suppresses the outflow of defective products, enabling stable quality control, and making it possible to provide vapor chambers 100 of good quality. Therefore, even in electronic devices equipped with the vapor chamber 100 of the present invention, heat dissipation failure is suppressed, and therefore defects in the electronic devices can be suppressed. Furthermore, the position of the optical identification structure 101 makes it easy to distinguish between the front and back and the top and bottom of the vapor chamber 100, facilitating process management.

[0030] [Vapor chamber configuration] Here, the internal structure of the vapor chamber shown in FIG. 1(a) and the internal structure of the metal sheet for the vapor chamber constituting the vapor chamber will be described with reference to FIG. 2 to FIG. 5. For simplicity, the optical identification structure acting as the ID according to the present invention is omitted in the description of the structure. The vapor chamber 800 has a sealed space 808 filled with a working liquid 807 as a flow path, and is a device for cooling a device D (cooled device) that generates heat, such as a central processing unit (CPU) used in mobile terminals such as mobile terminals and tablet terminals, by repeating phase changes of the working liquid 807 in the sealed space 808. The vapor chamber 800 has a generally thin, flat plate shape.

[0031] As shown in Fig. 2 and Fig. 3, the vapor chamber 800 has a flat plate shape and includes a lower metal sheet 810 having a flat plate shape with an upper surface 810a, and an upper metal sheet 820 having a flat plate shape provided on the lower metal sheet 810. The lower metal sheet 810 and the upper metal sheet 820 each correspond to a metal sheet for a vapor chamber. The upper metal sheet 820 has a lower surface 820a (the surface on the side of the lower metal sheet 810) superimposed on the upper surface 810a (the surface on the side of the upper metal sheet 820) of the lower metal sheet 810. In the example shown in Fig. 2, a device D, which is an object to be cooled, is attached to the lower surface 810b of the lower metal sheet 810 (particularly, the lower surface of the evaporation section 811 described later).

[0032] A sealed space 808 containing a hydraulic fluid 807 is formed between the lower metal sheet 810 and the upper metal sheet 820. Examples of the hydraulic fluid 807 include pure water, ethanol, methanol, and acetone.

[0033] The lower metal sheet 810 and the upper metal sheet 820 are joined by diffusion bonding or brazing, which will be described later. In the embodiment shown in Fig. 2 and Fig. 3, the lower metal sheet 810 and the upper metal sheet 820 are both formed in a rectangular shape in a plan view, but the present invention is not limited to this.

[0034] Here, a planar view refers to a state in which the vapor chamber 800 is viewed from a direction perpendicular to the surface that receives heat from device D (the lower surface 810b of the lower metal sheet 810) and the surface that releases the received heat (the upper surface 820b of the upper metal sheet 820), and corresponds to, for example, the state in which the vapor chamber 800 is viewed from above (see Figure 2) or from below.

[0035] When the vapor chamber 800 is installed in a mobile terminal, the vertical relationship between the lower metal sheet 810 and the upper metal sheet 820 may be lost depending on the posture of the mobile terminal. However, in the present invention, the metal sheet that receives heat from the device D is referred to as the lower metal sheet 810, and the metal sheet that dissipates the received heat is referred to as the upper metal sheet 820, and the description will be given with the lower metal sheet 810 disposed on the lower side and the upper metal sheet 820 disposed on the upper side. In addition, regarding the front and back sides, of the front and back sides of the vapor chamber 800, which is a flat plate, either the upper surface 820b of the upper metal sheet 820 or the lower surface 810b of the lower metal sheet 810 is referred to as the front side, and the other is referred to as the back side.

[0036] 4, lower metal sheet 810 has evaporation section 811 where working fluid 807 evaporates to generate steam, and lower steam flow path recess 812 that is provided on upper surface 810a and has a rectangular shape in plan view. Of these, lower steam flow path recess 812 constitutes a part of sealed space 808 described above, and is configured mainly to allow steam generated in evaporation section 811 to pass through.

[0037] The evaporation section 811 is disposed in this lower vapor flow path recess 812, and the vapor in the lower vapor flow path recess 812 diffuses in a direction away from the evaporation section 811, and most of the vapor is transported to the peripheral portion having a relatively low temperature. The evaporation section 811 is a portion where the working liquid 807 in the sealed space 808 evaporates upon receiving heat from the device D attached to the lower surface 810b of the lower metal sheet 810. For this reason, the term evaporation section 811 is used as a concept that is not limited to the portion overlapping the device D, but also includes a portion where the working liquid 807 can evaporate even if it does not overlap the device D.

[0038] As shown in FIG. 3 and FIG. 4, a plurality of lower flow passage walls 813 are provided in a lower steam flow passage recess 812 of a lower metal sheet 810, protruding upward (perpendicular to the bottom surface 812a) from a bottom surface 812a (described later) of the lower steam flow passage recess 812. In this example, the lower flow passage walls 813 are shown to extend in an elongated shape along the longitudinal direction (left-right direction in FIG. 4) of the vapor chamber 800, and include an upper surface 813a that abuts against a lower surface 823a of an upper flow passage wall 823 (described later). In addition, each lower flow passage wall 813 is disposed parallel to each other at equal intervals. In this manner, the vapor of the working fluid 807 flows around each lower flow passage wall 813, and the vapor is transported to the peripheral portion of the lower steam flow passage recess 812, suppressing the flow of the vapor from being impeded. Moreover, the lower flow passage wall 813 is disposed so as to overlap the corresponding upper flow passage wall 823 (described later) of the upper metal sheet 820 in a plan view, thereby improving the mechanical strength of the vapor chamber 800. The width of the lower flow passage wall 813 is, for example, 100 μm to 1500 μm, and the interval between the adjacent lower flow passage walls 813 is preferably 100 μm to 2000 μm. Here, the width of the lower flow passage wall 813 means the dimension of the lower flow passage wall 813 in a direction perpendicular to the longitudinal direction of the lower flow passage wall 813, and corresponds to, for example, the dimension in the up-down direction in FIG. 4. Moreover, the height h0 of the lower flow passage wall 813 (in other words, the depth of the lower vapor flow passage recess 812) (see FIG. 3) is preferably 100 μm to 300 μm.

[0039] 3 and 4, a lower peripheral wall 814 is provided on the peripheral portion of the lower metal sheet 810. The lower peripheral wall 814 is formed so as to surround the sealed space 808, particularly the lower steam flow path recess 812, and defines the sealed space 808. Furthermore, lower alignment holes 815 for aligning the lower metal sheet 810 and the upper metal sheet 820 are provided at the four corners of the lower peripheral wall 814 in a plan view.

[0040] The upper metal sheet 820 has substantially the same structure as the lower metal sheet 810, except that it is not provided with a lower liquid flow path recess 818, which will be described later. The configuration of the upper metal sheet 820 will be described in more detail below.

[0041] As shown in FIG. 3 and FIG. 5, the upper metal sheet 820 has an upper steam flow path recess 822 provided on the lower surface 820a. This upper steam flow path recess 822 constitutes a part of the sealed space 808, and is configured so that the steam generated in the evaporation section 811 mainly passes through it and cools the steam. More specifically, the steam in the upper steam flow path recess 822 diffuses in a direction away from the evaporation section 811, and most of the steam is transported to the peripheral portion having a relatively low temperature. Also, as shown in FIG. 3, a housing member H constituting a part of the housing of a mobile terminal or the like is disposed on the upper surface 820b of the upper metal sheet 820. As a result, the steam in the upper steam flow path recess 822 is cooled by the outside air via the upper metal sheet 820 and the housing member H.

[0042] 2 and 5, the upper flow path wall 823, the upper peripheral wall 824, and the upper alignment hole 825 of the upper metal sheet 820 are arranged to overlap the corresponding lower flow path wall 813, the lower peripheral wall 814, and the lower alignment hole 815 of the lower metal sheet 810 in a plan view, respectively, thereby improving the mechanical strength of the vapor chamber 800. Note that the width and height of the upper flow path wall 823 are preferably the same as the width and height h0 of the lower flow path wall 813 described above.

[0043] The lower metal sheet 810 and the upper metal sheet 820 are permanently bonded to each other, preferably by diffusion bonding. More specifically, the lower peripheral wall 814 and the upper peripheral wall 824 are bonded to each other. As a result, a sealed space 808 in which the working fluid 807 is sealed is formed between the lower metal sheet 810 and the upper metal sheet 820. In addition, each lower flow path wall portion 813 and the corresponding upper flow path wall portion 823 are bonded to each other. As a result, the mechanical strength of the vapor chamber 800 is improved.

[0044] As shown in FIG. 2, the vapor chamber 800 further includes an injection section 809 for injecting the working fluid 807 into the sealed space 808 at one end of a pair of ends in the longitudinal direction. The injection section 809 has a lower injection protrusion 816 protruding from an end face of the lower metal sheet 810 and an upper injection protrusion 826 protruding from an end face of the upper metal sheet 820. A lower injection flow path recess 817 is formed on the upper surface of the lower injection protrusion 816, and an upper injection flow path recess 827 is formed on the lower surface of the upper injection protrusion 826. The lower injection flow path recess 817 communicates with the lower steam flow path recess 812, and the upper injection flow path recess 827 communicates with the upper steam flow path recess 822. The lower injection flow path recess 817 and the upper injection flow path recess 827 form an injection flow path for the working fluid 807 when the lower metal sheet 810 and the upper metal sheet 820 are joined together.

[0045] As shown in Fig. 4, a lower liquid flow path recess 818 through which the liquid working fluid 807 passes is provided on an upper surface 813a of each lower flow path wall 813. The lower liquid flow path recess 818 constitutes a part of the above-mentioned sealed space 808, and communicates with the above-mentioned lower steam flow path recess 812 and upper steam flow path recess 822. The lower liquid flow path recess 818 is mainly configured to transport the working fluid 807 condensed from the steam generated in the evaporation section 811 to the evaporation section 811. In this example, the lower liquid flow path recess 818 extends in an elongated shape along the longitudinal direction of the lower flow path wall 813 (the left-right direction in Fig. 3), and extends from one end to the other end in the longitudinal direction of the lower flow path wall 813. In this way, the liquid working fluid 807 condensed on the periphery of the lower vapor flow path recess 812 and the periphery of the upper vapor flow path recess 822 is transported to the evaporation section 811 by capillary action. A plurality of lower liquid flow path recesses 818 are formed on an upper surface 813a of one lower flow path wall section 813, and the lower liquid flow path recesses 818 are arranged parallel to one another at equal intervals. Although not shown, the lower liquid flow path recesses 818 also communicate with the lower vapor flow path recesses 812 in the evaporation section 811.

[0046] The material used for the lower metal sheet 810 and the upper metal sheet 820 is not particularly limited as long as it has good thermal conductivity, but for example, it is preferable that the lower metal sheet 810 and the upper metal sheet 820 are formed of copper or a copper alloy. This can increase the thermal conductivity of the lower metal sheet 810 and the upper metal sheet 820. Therefore, the heat transport efficiency of the vapor chamber 800 can be increased. However, without being limited to the above, for example, a metal material in which different metals are laminated, such as a clad material (SUS / Cu rolled laminate material) or a plated material (SUS / Cu plating, Ni plating / rolled copper), may be used. In these cases, the strength can be higher than when it is made of copper or a copper alloy. In addition, the materials of the lower metal sheet 810 and the upper metal sheet 820 may be different. Furthermore, the thickness T0 of the vapor chamber 800 is 0.1 mm to 1.0 mm. Although the thickness T1 of the lower metal sheet 810 and the thickness T2 of the upper metal sheet 820 are shown to be equal, this is not limited thereto, and the thickness T1 of the lower metal sheet 810 and the thickness T2 of the upper metal sheet 820 do not have to be equal.

[0047] Second embodiment Incidentally, even in the first embodiment in which the optical identification structure 101 is formed in the peripheral region (the region where the upper peripheral wall 124 exists), there are cases in which it is difficult to read the optical identification structure 101. This is thought to be because the boundaries (grain boundaries) of the crystal grains of the metal material that constitutes the surface of the vapor chamber 100 (the upper surface 120b of the upper metal sheet 120 or the lower surface 110b of the lower metal sheet 110) impede the reading of the optical identification structure 101. As the crystal grains become larger due to heating during diffusion bonding, the crystal grain boundaries also become clear, and it is thought that fine irregularities due to the grain boundaries on the surface impede reading.

[0048] The second embodiment deals with the problem that the optical identification structure 201 acting as an ID becomes difficult to read due to the grain boundaries. The second embodiment of the present invention will be described with reference to Figs. 6 and 7. In the second embodiment, the optical identification structure 201 is formed on the upper surface 220b of the upper metal sheet 220 (or the lower surface 210b of the lower metal sheet 210) via the base layer 204. As shown in the top view of Fig. 6(a) and Fig. 7, the base layer 204 is formed in the base layer formation region 203. The base layer formation region 203 is a region that coincides with the region where the optical identification structure 201 exists in a plan view, or a region that includes the coincident region and the surrounding region. The base layer formation region 203 coincides with the region where the optical identification structure 201 exists in the minimum case, and is the entire surface of the vapor chamber 200 (the upper surface 220b of the upper metal sheet 220 or the lower surface 210b of the lower metal sheet 210) in the maximum case, as shown in Fig. 7. In other words, the base layer formation region 203 only needs to include an area that, when viewed in a planar view, coincides with the area in which the optical identification structure 201 exists, and can be determined appropriately taking into consideration the readability of the optical identification structure 201 and the load of forming the base layer 204 (process time, material costs), etc.

[0049] 6(b) shows a conceptual partial cross-sectional view of the vapor chamber 200 (upper metal sheet 220) cut in the short direction in a portion of the upper metal sheet 220 where the optical identification structure 201 acting as an ID is formed. Since FIG. 6(b) is a conceptual cross-sectional view, the positions of the optical identification structure 201 and the upper vapor flow path recess 222 are different from those in the top view of FIG. 6(a). As conceptually shown in FIG. 6(b), the base layer 204 is formed so as to cover minute irregularities caused by the boundaries (grain boundaries) of the crystal grains of the metal material constituting the top surface 220b of the upper metal sheet 220, so that the influence of the minute irregularities is almost eliminated on the surface of the base layer 204 on which the optical identification structure 201 is formed (the top surface of the base layer 204 in FIG. 6(b)).

[0050] The underlayer 204 is not particularly limited as long as it has a function of reducing the problem of the crystal grain boundaries hindering reading when the optical identification structure 201 is read, but it is preferable that the difference between the underlayer 204 and the optical identification structure 201 is large when reading. In other words, it is sufficient that the underlayer 204 has a function of making the crystal grain boundaries difficult to recognize when reading, and it is preferable that the difference between the underlayer 204 and the optical identification structure 201 is large. One example of the underlayer 204 is a single-color printing ink having a large brightness difference with respect to the optical identification structure 201, which is uniformly formed in the underlayer formation region 203. In this case, since the surface of the vapor chamber 200 is covered with the printing ink, the crystal grain boundaries become difficult to read, that is, the factor of hindering reading due to the crystal grain boundaries is reduced, and since the brightness difference between the printing ink and the optical identification structure 201 is large, the readability of the optical identification structure 201 formed on the printing ink is improved. Furthermore, since the printing ink is formed uniformly (so-called solid) without a pattern, it is possible to prevent the printing ink from hindering the readability of the optical identification structure 201.

[0051] The method of forming the base layer 204 by the printing ink is not particularly limited as long as it can be formed on the surface (upper surface 220b) of the upper metal sheet 220 or the surface (lower surface 210b) of the lower metal sheet 210, and is, for example, printing by the inkjet method. If it is the inkjet method, printing can be easily performed even after the upper metal sheet 220 or the lower metal sheet 210 is divided into individual pieces. If it is in a roll or sheet state before being divided into individual pieces, offset printing, gravure printing, screen printing, etc. are also possible. Although the above description has been given of the case where the base layer 204 is a printing ink, this is not limited to this. What is appropriate as the base layer 204 largely depends on the reading method of the optical identification structure 201. The base layer 204 may be formed by a sublimation transfer method, a vapor deposition method, a sputtering method, or other methods.

[0052] In this embodiment, the optical identification structure 201 is formed on the surface of the vapor chamber 200 via the underlayer 204. Therefore, when reading the optical identification structure 201, the problem of the crystal grain boundaries hindering reading can be alleviated, and the readability is improved. Therefore, it is possible to more reliably identify defective vapor chambers 200. This prevents the outflow of defective products, enabling stable quality control, and it is possible to provide vapor chambers 200 of good quality. Therefore, even in electronic devices equipped with the vapor chamber 200 of the present invention, heat dissipation failure is suppressed, and therefore defects in the electronic devices can be suppressed. In addition, the position of the optical identification structure 201 makes it easy to distinguish between the front and back or the top and bottom of the vapor chamber 200, making process management easier.

[0053] Third embodiment Next, a third embodiment will be described. In the form in which the base layer 204 described in the second embodiment is formed, it is often not necessary to form the optical identification structure 201 in the peripheral region (the region in which the upper peripheral wall 224 exists). This is because the base layer 204 often simultaneously improves the above-mentioned conventional problem that the outline shape of the upper steam flow path recess 222 adversely affects the reading of the optical identification structure 201 as a background pattern.

[0054] As shown in Figures 8(a) and (b), in the third embodiment, the optical identification structure 301 acting as an ID does not have to be formed in the peripheral region as long as it is formed via the base layer 304. Figure 8(a) is a top view, and Figure 8(b) is a partial cross-sectional conceptual diagram of the vapor chamber 300 (upper metal sheet 320) cut in the short direction in the portion of the upper metal sheet 320 where the optical identification structure 301 acting as an ID is formed. Figure 8(b) is a conceptual cross-sectional view, and therefore the positions of the optical identification structure 301 and the upper vapor flow path recess 322 are different from those in the top view of Figure 8(a). 8(b), particularly when the thickness of the underlayer 304 is thick, even if there are irregularities in the contour shape of the upper vapor flow path recess 322 (lower vapor flow path recess 312) on the surface of the vapor chamber 300 (upper surface 320b of the upper metal sheet 320 or lower surface 310b of the lower metal sheet 310), the irregularities in the contour shape of the upper vapor flow path recess 322 (lower vapor flow path recess 312) hardly appear on the surface of the underlayer 304 (the surface opposite to the surface where the underlayer 304 contacts the surface of the vapor chamber 300 (upper surface 320b of the upper metal sheet 320)). That is, in the third embodiment, the underlayer 304 also has the effect of flattening the target surface on which the optical identification structure 301 is formed.

[0055] In the third embodiment, similarly to the second embodiment, the base layer forming region 303 only needs to include a region that coincides with the region where the optical identification structure 301 is present in a plan view, and may be formed on the entire surface of the vapor chamber 300 (upper surface 320b of the upper metal sheet 320, or lower surface 310b of the lower metal sheet 310) as shown in Fig. 7. The method of forming the base layer 304 is also similar to that exemplified in the second embodiment.

[0056] The third embodiment also has the above-mentioned effects described in the second embodiment. In addition, in the third embodiment, the optical identification structure 301 does not need to be formed in the peripheral region, so the degree of freedom in the formation position of the optical identification structure 301 is improved. Therefore, restrictions on the installation position, etc. of the device that forms the optical identification structure 301 and the device that reads it can be reduced, which has the effect of making it easier to select and install these devices.

[0057] (Fourth embodiment) A fourth embodiment of the present invention will be described with reference to Figs. 9 and 10. In the fourth embodiment, an optical identification structure 401 acting as an ID is formed on a smooth surface on the surface of the vapor chamber 400 (the upper surface 420b of the upper metal sheet 420 or the lower surface 410b of the lower metal sheet 410) where the height difference between the part with the internal space and the part without the internal space is 30 µm or less. As shown in the top view of Fig. 9(a) and Fig. 10, the smooth surface is formed in a smooth surface forming region 405. In a plan view, the smooth surface forming region 405 is a region that coincides with the region where the optical identification structure 401 exists, or a region that includes the coincident region and the surrounding region. When the smooth surface forming region 405 is at its minimum, it coincides with the region where the optical identification structure 401 exists, and when it is at its maximum, it is the entire surface of the vapor chamber 400 (the upper surface 420b of the upper metal sheet 420 or the lower surface 410b of the lower metal sheet 410) as shown in Fig. 10. That is, the smooth surface forming region 405 may include a region that coincides with the region in which the optical identification structure 401 exists in a plan view, and may be appropriately determined in consideration of the readability of the optical identification structure 401, the load (process time) for forming the smooth surface, etc. In this case, it is desirable that the maximum height roughness Rz is 1 μm or less.

[0058] FIG. 9(b) shows a conceptual partial cross-sectional view of the vapor chamber 400 (upper metal sheet 420) cut in the short direction at a portion of the upper metal sheet 420 where the optical identification structure 401 acting as an ID is formed. Since FIG. 9(b) is a conceptual cross-sectional view, the positions of the optical identification structure 401 and the upper steam flow path recess 422 are different from those of the top view of FIG. 9(a). As conceptually shown in FIG. 9(b), the fine irregularities caused by the boundaries (grain boundaries) of the crystal grains of the metal material constituting the upper surface 420b of the upper metal sheet 420 and the influence of the formation of the upper steam flow path recess 422 extending to the upper surface 420b of the upper metal sheet 420 are significantly reduced by the formation of a smooth surface. That is, by forming a smooth surface, the maximum height roughness Rz is 1 μm or less, and the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less.

[0059] The smooth surface formed in the smooth surface forming region 405 can be formed, for example, by polishing the surface (upper surface 420b) of the upper metal sheet 420 or the surface (lower surface 410b) of the lower metal sheet 410. Any of chemical polishing, electrolytic polishing, and mechanical polishing can be used as the polishing method. It is possible to polish only the smooth surface forming region 405 by masking the region not to be polished with a resist or the like and applying chemical polishing or electrolytic polishing. In mechanical polishing, after polishing with Emily paper, the grain size of the abrasive grains may be changed by buff polishing with alumina abrasive grains or the like. In each polishing method, the polishing conditions may be appropriately determined so that the maximum height roughness Rz is 1 μm or less and the height difference between the part with internal space and the part without internal space is 30 μm or less.

[0060] The height difference between the part with internal space and the part without internal space can be confirmed as follows: Using a laser microscope (Keyence Corporation, VK-X250), a profile is obtained with an objective lens of 20x magnification, and the height difference between the peripheral region without internal space and the part with internal space is measured.

[0061] The maximum height roughness Rz of the smooth surface forming region 405 can be measured based on "JIS B 0601:2001". An example of measurement when the smooth surface forming region 405 is formed on the surface (upper surface 420b) of the upper metal sheet 420 is shown below. A laser microscope (Keyence Corporation, VK-X250) is used, and the measurement direction is preferably a direction perpendicular to the upper steam flow passage recess 422 and the upper flow passage wall portion 423 that extend in an elongated shape along the longitudinal direction (left-right direction in FIG. 9) of the vapor chamber 400 in a plan view (the short side direction of the vapor chamber 400 in a plan view (the up-down direction in FIG. 9)). The maximum height roughness Rz of the smooth surface forming region 405 can be measured by setting the laser wavelength to 408 nm, the objective lens to 100x or 150x, and other parameters appropriately.

[0062] In the fourth embodiment, the optical identification structure 401 is formed on a smooth surface on the surface of the vapor chamber 400 (the upper surface 420b of the upper metal sheet 420, or the lower surface 410b of the lower metal sheet 410) with a height difference of 30 μm or less between a portion with an internal space and a portion without an internal space, so that it is possible to significantly suppress the above-mentioned problem that the outline shape of the upper vapor flow path recess 422 acts as a background pattern and adversely affects the reading of the optical identification structure 401. Therefore, unlike the first embodiment, it is not necessary to form the optical identification structure 401 in the peripheral region (the region where the upper peripheral wall 424 exists), and it can be formed in any position as in the third embodiment.

[0063] Furthermore, when the laser marking method is used and one side of the marking area is 1 mm or more and 3 mm or less, a smooth surface with a maximum height roughness Rz of 1 μm or less can be obtained. This polishing makes it possible to reduce the fine depressions caused by grain boundaries compared to the surface before polishing, and significantly reduces the above-mentioned problem that the grain boundaries act as a background pattern and adversely affect the reading of the optical identification structure 401.

[0064] Due to the above effects, even in the fourth embodiment, it is possible to reliably identify defective vapor chambers 400. This prevents the outflow of defective products, enabling stable quality control and providing vapor chambers 400 of good quality. Therefore, even in electronic devices equipped with the vapor chamber 400 of the present invention, heat dissipation failure is suppressed, so that defects in the electronic devices can be suppressed. Furthermore, the position of the optical identification structure 401 makes it easy to distinguish between the front and back and the top and bottom of the vapor chamber 400, facilitating process management.

[0065] In the smooth surface of the fourth embodiment, it is preferable that the difference in height between the portion with internal space and the portion without internal space is 30 μm or less, and the maximum height roughness Rz is 1 μm or less. However, it is also possible to satisfy only one of the conditions. That is, if the difference in height between the portion with internal space and the portion without internal space is 30 μm or less, the above-mentioned effect of significantly suppressing the adverse effects due to the contour shape of the upper steam flow path recess 422 can be obtained, and if the maximum height roughness Rz is 1 μm or less, the above-mentioned effect of significantly suppressing the adverse effects due to the grain boundaries can be obtained.

[0066] Next, an example of a manufacturing method of the vapor chamber 400 in the fourth embodiment will be outlined. The manufacturing method of the vapor chamber 400 in the fourth embodiment includes at least a step of polishing a portion where the optical identification structure 401 acting as an ID is to be formed, and a step of forming the optical identification structure 401 acting as an ID on the polished portion, in this order. FIG. 11 shows a partial cross-sectional conceptual diagram of a characteristic step in the fourth embodiment, among an example of a manufacturing method of the vapor chamber 400 in the fourth embodiment. FIG. 11 is a partial cross-sectional conceptual diagram of a portion of the upper metal sheet 420 where the optical identification structure 401 acting as an ID is formed, in which the vapor chamber 400 (upper metal sheet 420) is cut in the short direction, and although it is actually joined to the lower metal sheet 410, only the upper metal sheet 420 is shown.

[0067] As an example, first, a lower metal sheet 410 in which a lower vapor flow passage recess 412 and a lower liquid flow passage recess 418 are formed, and an upper metal sheet 420 in which an upper vapor flow passage recess 422 is formed are prepared.

[0068] In this case, first, a resist film R is formed on the upper surface of the metal material sheet M. For the resist film R, an electrodeposition resist material that can be attached by an electric field can be suitably used, but other materials such as a liquid resist material may also be used as long as the resist film R can be formed on the metal material sheet M.

[0069] Next, the resist film R is patterned. In the case of the lower metal sheet 410, resist openings corresponding to the lower vapor flow path recesses 412 and lower liquid flow path recesses 418 are formed in the resist film R by photolithography.

[0070] Subsequently, in a half-etching process, the opening portion of the resist film R is half-etched to form the lower vapor flow channel recess 412, the lower flow channel wall 413, and the lower peripheral wall 414. At this time, the lower liquid flow channel recess 418 is formed on the upper surface 413a of the lower flow channel wall 413. In addition, the lower injection flow channel recess 417 shown in FIG. 2 and FIG. 4 is also formed at the same time, and the metal material sheet M is etched from the upper surface and the lower surface so as to have an outer contour shape as shown in FIG. 2, and a predetermined outer contour shape is obtained. 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 limited to half the thickness of the lower metal sheet 410. For example, an iron chloride-based etching solution such as a ferric chloride aqueous solution, or a copper chloride-based etching solution such as a copper chloride aqueous solution can be used as the etching solution.

[0071] Thereafter, the resist film R is removed, and a lower metal sheet 410 is obtained in which a lower vapor flow path recess 412, a lower flow path wall 413, a lower peripheral wall 414 and a lower liquid flow path recess 418 are formed.

[0072] Meanwhile, in the same manner as the lower metal sheet 410, the upper metal sheet 420 is half-etched from the lower surface 420a to form the upper steam flow path recess 422, the upper flow path wall 423, and the upper peripheral wall 424. In this manner, the above-mentioned upper metal sheet 420 is obtained.

[0073] Next, the lower metal sheet 410 and the upper metal sheet 420 are bonded together. At this time, the lower alignment holes 415 and the upper alignment holes 425 are aligned and temporarily fixed, and in this state, pressure and heat are applied to permanently bond them by diffusion bonding.

[0074] In this case, first, the lower metal sheet 410 and the upper metal sheet 420 are aligned using the lower alignment hole 415 (see FIGS. 2 and 4) of the lower metal sheet 410 and the upper alignment hole 425 (see FIGS. 2 and 5) of the upper metal sheet 420. Next, the lower metal sheet 410 and the upper metal sheet 420 are temporarily fixed together. The method of temporarily fixing is not particularly limited, but for example, the lower metal sheet 410 and the upper metal sheet 420 may be temporarily fixed together by resistance welding the lower metal sheet 410 and the upper metal sheet 420. In this way, the lower metal sheet 410 and the upper metal sheet 420 are temporarily fixed together in an aligned state.

[0075] After the temporary fixing, the lower metal sheet 410 and the upper metal sheet 420 are permanently bonded by diffusion bonding (FIG. 11(a)). Diffusion bonding is a method in which the lower metal sheet 410 and the upper metal sheet 420 to be bonded are brought into close contact with each other, and in a controlled atmosphere such as a vacuum or an inert gas, the metal sheets 410, 420 are pressurized in a direction in which they are brought into close contact with each other and heated, thereby utilizing the diffusion of atoms that occurs at the bonding surfaces. In diffusion bonding, the materials of the lower metal sheet 410 and the upper metal sheet 420 are heated to a temperature close to the melting point, but lower than the melting point, so that it is possible to prevent the metal sheets 410, 420 from melting and deforming.

[0076] Next, the portion where the optical identification structure 401 is to be formed is polished. That is, chemical polishing is performed on the entire surface of either the upper surface 420b of the upper metal sheet 420 or the lower surface 410b of the lower metal sheet 410, so that the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less, and the maximum height roughness Rz is 1 μm or less. An example of chemical polishing on the entire surface is shown in FIG. 11(b), but if the smooth surface forming region 405 is not the entire surface, the region other than the smooth surface forming region 405 may be masked with a resist or the like before chemical polishing. The chemical polishing liquid may be appropriately selected from nitric acid-sulfuric acid-hydrochloric acid-based polishing liquid (commonly known as Kirinsu liquid), hydrogen peroxide-sulfuric acid-based polishing liquid, phosphoric acid-based polishing liquid, and the like. In addition, the processing time and liquid temperature are appropriately set so that the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less, and the maximum height roughness Rz is 1 μm or less.

[0077] Next, the optical identification structure 401 is formed on the polished portion. That is, the optical identification structure 401 is formed on a part of the smooth surface forming region 405 (FIG. 11(c)). The optical identification structure 401 in the present invention is formed as a structure that can optically read numbers, letters, symbols, two-dimensional codes such as QR codes, or bar codes, and is optically read by equipment such as a camera, scanner, or reader, or by visual inspection. The optical identification structure 401 is often formed by printing using an inkjet method, laser printing, engraving, etc., but the formation method is not limited to these as long as it is formed to be optically readable. As an example, a QR code is printed by an inkjet printer. The ID information held by the formed optical identification structure 401 is individually different. The ID information is used to clearly distinguish each of the vapor chambers in the process of being formed by associating lot management, air pressure conditions when injecting a fluid that carries heat transport, and inspection results for the amount of the fluid injected with each of the vapor chambers in the process of being formed.

[0078] Next, the sealed space 408 is depressurized, and then the working liquid 407 is injected into the sealed space 408 from the injection flow path formed by the lower injection flow path recess 417 and the upper injection flow path recess 427. The working liquid 407 is, for example, pure water. Then, for example, a laser is irradiated onto the injection part 409 to partially melt the injection part 409 and seal the injection flow path. This completes the vapor chamber 400.

[0079] As an example of utilizing the optical identification structure 401 in the above process, in the process of injecting the working liquid 407 and sealing, the optical identification structure 401 (QR code) is read by a scanner, and the amount of working liquid 407 injected, which may vary in each vapor chamber 400, and the actual measured value of the pressure in the sealed space 408 at the time of sealing are associated with each vapor chamber 400. When reading the optical identification structure 401 (QR code) with a scanner as described above, the surface on which the optical identification structure 401 is formed is entirely polished to be a smooth surface.

[0080] In addition, on the smooth surface, the difference in height between the portion with internal space and the portion without internal space is 30 μm or less. Therefore, it is possible to significantly suppress the above-mentioned problem that the outline shape of upper steam flow path recess 422 adversely affects the reading of optical identification structure 401 as a background pattern.

[0081] Moreover, the smooth surface has a maximum height roughness Rz of 1 μm or less, which has the effect of significantly suppressing the above-mentioned problem that the grain boundaries act as a background pattern and adversely affect the reading of the optical identification structure 401.

[0082] In the above process example, the above-mentioned effects allow for reliable identification of defective vapor chambers 400. This prevents the outflow of defective products, enabling stable quality control and providing vapor chambers 400 of good quality. Therefore, in electronic devices equipped with the vapor chamber 400 of the present invention, poor heat dissipation is prevented, and defects in the electronic devices can be prevented. Furthermore, the position of the optical identification structure 401 makes it easy to distinguish between the front and back and the top and bottom of the vapor chamber 400, facilitating process management.

[0083] Although the embodiments have been described above, the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0084] 100, 200, 300, 400, 800, 900 Vapor Chamber 101, 201, 301, 401, 901 Optical identification structure 203, 303 Base layer formation area 204, 304 Base layer 405 Smooth surface formation area 407, 807 Hydraulic Fluid 408, 808 Sealed space 409, 809 Injection part 110, 210, 310, 410, 810, 910 Lower metal sheet 810a top side 110b, 210b, 310b, 410b, 810b, 910b Bottom 811 Evaporation section 112, 312, 412, 812 Lower steam passage recess 812a Bottom 413, 813 Lower channel wall 413a, 813a top surface 114, 414, 814 Lower perimeter wall 415, 815 Lower alignment holes 816 Lower injection protrusion 417, 817 Lower injection channel recess 418, 818 Lower liquid flow passage recess 120, 220, 320, 420, 820, 920 Upper metal sheet 420a, 820a bottom side 120b, 220b, 320b, 420b, 820b, 920b Top 122, 222, 322, 422, 822, 922 Upper steam passage recess 423, 823, 923 Upper channel wall 823a Bottom side 124, 224, 424, 824, 924 Upper Peripheral Wall 425, 825 Upper alignment holes 826 Upper injection protrusion 427, 827 Upper injection channel recess D Device H Housing material M Metallic material sheet R resist film

Claims

1. A flat vapor chamber having a flow path for a fluid responsible for heat transport therein, an optical identification structure acting as an ID is formed on a surface of the vapor chamber; A vapor chamber, wherein the optical identification structure is formed on a smooth surface spanning a portion of the surface of the vapor chamber where there is a vapor passage and a portion where there is no vapor passage.

2. A flat vapor chamber having a flow path for a fluid responsible for heat transport therein, A vapor chamber in which an optical identification structure acting as an ID has a shape different from the contour shape of the flow path and is formed on a smooth surface having a maximum height roughness Rz of 1 μm or less.

3. A flat vapor chamber having a flow path for a fluid responsible for heat transport therein, an optical identification structure acting as an ID is formed on a surface of the vapor chamber; A vapor chamber, wherein the optical identification structure is formed on a smooth surface having a maximum height roughness Rz of 1 μm or less.

4. An electronic device equipped with a vapor chamber described in any one of claims 1 to 3.

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