JP7167601B2 - Vapor chamber and manufacturing method of vapor chamber - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor chamber having therein a fluid channel for heat transport, and a manufacturing method thereof.

Devices that generate heat, such as central processing units (CPUs) used in mobile terminals such as mobile terminals and tablet terminals, are cooled by heat-radiating members such as heat pipes (see, for example, Patent Document 1). In recent years, in order to reduce the thickness of mobile terminals and the like, there is a demand for reducing the thickness of heat-dissipating members, and the development of vapor chambers that can be made thinner than heat pipes is underway.

A vapor chamber is a device that applies the mechanism of heat transport by a heat pipe to a flat member (metal sheet). That is, in the vapor chamber, a fluid that transports heat is enclosed between flat plate-like members that are arranged facing each other and joined together. Transport and diffuse to cool the heat source.

For example, there is a form in which a vapor channel and a condensate channel are provided between opposed flat plate members of the vapor chamber, and a fluid responsible for heat transport is enclosed therein. When the vapor chamber is placed near the heat source, the fluid that transports heat near the heat source evaporates by receiving heat from the heat source, becomes gas (vapor), and moves through the vapor channel. This allows the heat from the heat source to be smoothly transported away from the heat source, thereby cooling the heat source.
The gaseous fluid that has transported the heat from the heat source moves to a position away from the heat source, where the heat is absorbed by the surroundings, where it is cooled, condensed, and undergoes a phase change to a liquid state. The liquid phase-changed fluid passes through the condensate flow path, returns to the position of the heat source, receives heat from the heat source, evaporates, and changes to a gaseous state.
The heat generated from the heat source is transported to a position away from the heat source by the circulation as described above, and the heat source is cooled.

The joining between the opposing plate-shaped 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). .

JP 2016-205693 A Japanese Unexamined Patent Application Publication No. 2007-212028 JP 2012-132582 A

By the way, an optical identification structure that acts as an ID may be formed on the front surface or the rear surface of each vapor chamber that is in the process of forming a flat plate after the flat members are joined. The ID information possessed by the formed optical identification structure is individually different for each of the vapor chambers in the process of formation. This is because it is necessary to clearly distinguish each of the vapor chambers in the process of formation in order to relate to lot management, atmospheric pressure conditions when injecting the fluid responsible for heat transport, and test results for the injection amount of the fluid.

The optical identification structure is formed by ink-jet printing, laser printing, or engraving on the front or back surface of the vapor chamber in the process of being formed, and the optical identification structure thus formed can be viewed visually, using a camera, a scanner, or the like. It is often read by optical means such as a reader.

FIG. 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. FIG. A QR code, which is an optical identification structure 901, is formed for each vapor chamber 900, and ID information possessed by each optical identification structure 901 (QR code) is individually different. Therefore, each vapor chamber 900 can be individually identified.

The optical identification structure 901, when it is a QR code, preferably has a side length of 1 mm or more. If each cell inside the QR code has a certain size or more, the change in the formation condition of the optical identification structure 901 forming the QR code, the upper surface 920b of the upper metal sheet 920 on which it is formed, or This is because the surface condition of the lower surface 910b of the lower metal sheet 910 does not affect the surface condition of the lower metal sheet 910, thereby enabling more stable reading.

If the optical identification structure 901 can be accurately read visually, by optical means such as a camera, a scanner, or a reader, the ID information possessed by the optical identification structure 901 can be used when injecting a fluid responsible for heat transport. The air pressure condition, the inspection result for the amount of injection of the fluid, or the function inspection result after hermetic sealing and each vapor chamber 900 are associated with each other, or lot management can be performed reliably and easily. By suppressing the outflow of defective products, stable quality control becomes possible, and the vapor chamber 900 of good quality can be provided. In an electronic device in which such a vapor chamber 900 is mounted, poor heat dissipation is also suppressed, so it is possible to suppress defects in the electronic device. Further, the position of the optical identification structure 901 makes it easy to distinguish between the front and back and top and bottom of the vapor chamber 900, which facilitates process management.

By the way, as described above, when the optical identification structure 901 is read visually, by an optical means such as a camera, a scanner, or a reader, the relationship between the optical identification structure 901 and the surface of the member serving as the background , the problem may arise that the optical identification structure 901 becomes difficult to read. The main reason for this is that the shape of the internal sealed space becomes a pattern on the upper surface 920b of the upper metal sheet 920 on which the optical identification structure 901 is formed or the lower surface 910b of the lower metal sheet 910, and the optical identification structure 901 is formed. to prevent reading by any means.

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 inside the upper steam channel recess 922 or inside the upper channel wall 923 in a plan view, and does not fit inside the upper steam channel recess 922 . and the upper steam channel wall portion 923, or the boundary between the upper steam channel recess 922 and the upper peripheral wall 924, that is, the contour of the upper steam channel recess 922, or the contour is immediately adjacent to the optical identification structure 901. will exist in FIG. 12(b) is a partial cross section of the vapor chamber 900 (upper metal sheet 920) cut in the lateral direction at the portion of the upper metal sheet 920 where the optical identification structure 901 acting as an ID is formed. A conceptual diagram is shown. Since FIG. 12(b) is a diagram conceptually showing a cross section, the positions of the optical identification structure 901 and the upper steam flow channel concave portion 922 are different from the top view of FIG. 12(a). there is As conceptually shown in FIG. 12( b ), the upper surface 920 b of the upper metal sheet 920 is affected by whether or not the upper steam flow passage recess 922 is formed. When reading the optical identification structure 901, the outline of the upper vapor channel recess 922 exists within the reading area, and the outline interferes with the reading by the optical means.

That is, as described above, the vapor chamber 900 is formed by bonding the opposed flat plate members, and diffusion bonding may be used for the bonding. Diffusion bonding is to pressurize and heat the above-mentioned flat plate-like members in close contact with each other. As a result, reading by the above optical means may be hindered. The flat plate-shaped member has a sealed space, that is, a groove that serves as a flow path for a fluid responsible for heat transport. If the shape of the groove (whether or not there is a groove) formed on the opposite side) becomes a pattern on the opposite side, that is, on the front or back side of the vapor chamber in the process of formation, which hinders reading by the above optical means There is The groove shape (whether or not there is a groove) in a flat plate member affects the opposite side because the plate thickness of the flat plate member is very thin especially in the part where the groove is formed, so during diffusion bonding It is presumed that the degree of fine deformation of the plate-like member due to pressure is slightly different between the grooved portion and the non-grooved portion. Also, brazing is sometimes used for joining, but the same problem may occur although the temperature and pressure are different.

In view of the above, an object of the present invention is to provide a vapor chamber in which an optical identification structure that acts as an ID is formed on the front or back surface, and the optical identification structure is visually observed, or optically detected by a camera, scanner, reader, or the like. To provide a vapor chamber of good quality by enabling stable quality control by enhancing readability when reading by means.

The present invention relates to a flat vapor chamber having a flow path for a fluid that transports heat therein, comprising a flow path area in which the flow path is formed and a peripheral edge area that surrounds the flow path area in a plan view. , and an optical identification structure acting as an ID is formed in the peripheral region of the vapor chamber.

In the above invention, the optical identification structure acting as an ID may be formed via an underlying layer.

The present invention is a flat vapor chamber having therein a 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.

The present invention is a flat vapor chamber having therein a flow path for a fluid responsible for heat transport, wherein 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. It is a formed vapor chamber.

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

The present invention is a method for manufacturing a planar vapor chamber having therein a flow path for a fluid responsible for heat transport and having an optical identification structure acting as an ID. A vapor chamber manufacturing method comprising, in order, a step of polishing a portion where an identification structure is to be formed, and a step of forming an optical identification structure acting as the ID on the polished portion.

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

In the above invention, the step of polishing the portion forming the optical identification structure acting as the ID is a step of polishing so that the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less. , a vapor chamber manufacturing method.

According to the present invention, in a vapor chamber in which an optical identification structure acting as an ID is formed on the front or back surface, when the optical identification structure is read visually, by a camera, a scanner, or by an optical means such as a reader. By improving the readability of the number, it is possible to perform stable management and thereby provide a vapor chamber of good quality.

BRIEF DESCRIPTION OF THE DRAWINGS (a) Top view and (b) partial cross-sectional conceptual diagram which show the vapor chamber by 1st Embodiment of this invention. FIG. 2 is a top view for explaining the internal structure of the vapor chamber shown in FIG. 1; A cross-sectional view of the vapor chamber of FIG. 2 along the line AA. FIG. 3 is a top view of the lower metal sheet of FIG. 2; FIG. 3 is a bottom view of the upper metal sheet of FIG. 2; (a) Top view and (b) partial cross-sectional conceptual view showing a vapor chamber according to a second embodiment of the present invention. FIG. 5 is a top view showing a vapor chamber according to another example of the second embodiment of the invention; (a) A top view and (b) a conceptual partial cross-sectional view showing a vapor chamber according to a third embodiment of the present invention. (a) A top view and (b) a conceptual partial cross-sectional view showing a vapor chamber according to a fourth embodiment of the present invention. FIG. 11 is a top view showing a vapor chamber according to another example of the fourth embodiment of the invention; FIG. 11 is a conceptual partial cross-sectional view showing a method of manufacturing a vapor chamber according to a fourth embodiment of the present invention; (a) Top view and (b) partial cross-sectional conceptual view showing a conventional vapor chamber.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, for the sake of ease of illustration and understanding, the scale and the ratio of vertical and horizontal dimensions are changed and exaggerated from the actual ones.

(First embodiment)
FIG. 1(a) shows a plan view (top view) of the vapor chamber 100 according to the first embodiment of the present invention as seen from above (surface). In the vapor chamber 100 of FIG. 1(a), an optical identification structure 101 is formed on the upper surface 120b of the upper metal sheet 120 to act as an ID. The vapor chamber 100 has, in plan view, a channel area in which an upper vapor channel recess 122 (lower steam channel recess 112) is formed, and a peripheral area surrounding the channel area, namely an upper peripheral wall 124 ( and a region where the lower peripheral wall 114) is present, and in the first embodiment, the optical identification structure 101 is formed in the peripheral region (the region where the upper peripheral wall 124 is present).

In the formation position of the optical identification structure 101 in the first embodiment shown in FIG. ing. FIG. 1(b) is a partial cross section of the vapor chamber 100 (upper metal sheet 120) cut in the lateral direction at the portion of the upper metal sheet 120 where the optical identification structure 101 acting as an ID is formed. A conceptual diagram is shown. Since FIG. 1(b) is a diagram showing a conceptual cross section, the positions of the optical identification structure 101 and the upper vapor channel recess 122 are different from the top view of FIG. 1(a). there is Since the entire optical identification structure 101 is contained within the region where the upper peripheral wall 124 exists (the peripheral region, that is, the region where the upper steam flow channel recess 122 is not formed), conceptually shown in FIG. 2, the formation of the upper steam channel recesses 122 hardly affects the upper surface 120b of the upper metal sheet 120. As shown in FIG.

That is, the conventional problem that the contour shape of the upper vapor channel concave portion 122 adversely affects reading of the optical identification structure 101 as a background pattern can be greatly suppressed. Therefore, the readability of the optical identification structure 101 is improved, and the defective vapor chamber 100 can be reliably identified. By suppressing the outflow of defective products, stable quality control becomes possible, and the vapor chamber 100 of good quality can be provided. Therefore, even in an electronic device in which the vapor chamber 100 of the present invention is mounted, heat radiation failure is suppressed, so that failure of the electronic device can be suppressed. Further, the position of the optical identification structure 101 makes it easy to distinguish between the front and back and top and bottom of the vapor chamber 100, which facilitates process control.

[Configuration of vapor chamber]
2 to 5, the internal structure of the vapor chamber shown in FIG. 1(a) and the internal structure of the vapor chamber metal sheet that constitutes the vapor chamber will be described. For simplicity, the description of the structure omits the optical identification structure that serves as the ID according to the present invention. The vapor chamber 800 has a sealed space 808 in which a working fluid 807 is enclosed as a flow path. It is a device for cooling a device D (device to be cooled) that generates heat such as a central processing unit (CPU) used. Vapor chamber 800 generally has a thin flat plate-like configuration.

As shown in FIGS. 2 and 3, the vapor chamber 800 has a flat shape, a lower metal sheet 810 having a flat shape with an upper surface 810a, and a lower metal sheet 810 provided on the lower metal sheet 810. and an upper metal sheet 820 having a flat plate-like configuration. Both the lower metal sheet 810 and the upper metal sheet 820 correspond to vapor chamber metal sheets. The upper metal sheet 820 has a lower surface 820a (the surface on the lower metal sheet 810 side) that overlaps the upper surface 810a of the lower metal sheet 810 (the surface on the upper metal sheet 820 side). A device D, which is an object to be cooled in the example shown in FIG.

Between the lower metal sheet 810 and the upper metal sheet 820, a sealed space 808 in which hydraulic fluid 807 is enclosed is formed. Examples of the working liquid 807 include pure water, ethanol, methanol, acetone, and the like.

The lower metal sheet 810 and the upper metal sheet 820 are joined by diffusion bonding or brazing, which will be described later. 2 and 3 show examples in which lower metal sheet 810 and upper metal sheet 820 are both rectangular in plan view, but are not limited to this.

Here, the plane view is a direction perpendicular to the surface of the vapor chamber 800 that receives heat from the 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). , which corresponds to, for example, a state in which the vapor chamber 800 is viewed from above (see FIG. 2) or a state in which it is viewed from below.

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 disrupted depending on the orientation of the mobile terminal. However, in the present invention, the metal sheet that receives heat from the device D is called the lower metal sheet 810, the metal sheet that releases the received heat is called the upper metal sheet 820, and the lower metal sheet 810 is on the lower side. are arranged, and the upper metal sheet 820 is arranged on the upper side. Regarding the front and back surfaces, of the front and back surfaces of the vapor chamber 800, which is flat, 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 surface, and the other is referred to as the back surface. called.

As shown in FIG. 4, the lower metal sheet 810 includes an evaporator 811 in which the working fluid 807 evaporates to generate steam, and a lower steam channel provided on the upper surface 810a and formed in a rectangular shape in plan view. and a recess 812 . Of these, the lower steam flow path concave portion 812 constitutes a part of the sealed space 808 described above, and is mainly configured so that the steam generated in the evaporating portion 811 passes therethrough.

The evaporator 811 is arranged in the lower steam channel recess 812, and the steam in the lower steam channel recess 812 diffuses away from the evaporator 811, and most of the steam is relatively It is transported to the cooler periphery. Note that the evaporating portion 811 is a portion where the working fluid 807 in the sealed space 808 evaporates by receiving heat from the device D attached to the lower surface 810b of the lower metal sheet 810 . Therefore, the term evaporating portion 811 is not limited to the portion overlapping the device D, but is used as a concept including a portion that does not overlap the device D but allows the working fluid 807 to evaporate.

As shown in FIGS. 3 and 4, in the lower steam channel recess 812 of the lower metal sheet 810, from the bottom surface 812a (described later) of the lower steam channel recess 812 upward (perpendicular to the bottom surface 812a) A plurality of projecting lower channel walls 813 are provided. In this example, the lower channel wall portion 813 extends in an elongated shape along the longitudinal direction of the vapor chamber 800 (horizontal direction in FIG. 4). 823 includes an upper surface 813a that abuts a lower surface 823a. In addition, the respective lower channel wall portions 813 are spaced apart at equal intervals and arranged parallel to each other. In this manner, the vapor of the working fluid 807 flows around each lower flow path wall portion 813 and is transported to the peripheral edge portion of the lower vapor flow path concave portion 812. Prevents obstruction of flow. In addition, the lower channel wall portion 813 is arranged so as to overlap the corresponding upper channel wall portion 823 (described later) of the upper metal sheet 820 in a plan view, thereby improving the mechanical strength of the vapor chamber 800. ing. The width of the lower channel wall portion 813 is, for example, 100 μm to 1500 μm, and the interval between adjacent lower channel wall portions 813 is preferably 100 μm to 2000 μm. Here, the width of the lower channel wall portion 813 means the dimension of the lower channel wall portion 813 in the direction perpendicular to the longitudinal direction of the lower channel wall portion 813. For example, the width of the lower channel wall portion 813 in FIG. Corresponds to the vertical dimension. Also, the height of the lower flow path wall portion 813 (in other words, the depth of the lower steam flow path concave portion 812) h0 (see FIG. 3) is preferably 100 μm to 300 μm.

As shown in FIGS. 3 and 4, the lower metal sheet 810 has a lower peripheral wall 814 around its periphery. A lower peripheral wall 814 is formed to surround the sealed space 808 , particularly the lower steam channel recess 812 , to define the sealed space 808 . 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 plan view.

The upper metal sheet 820 has substantially the same structure as the lower metal sheet 810, except that the lower liquid flow path recesses 818, which will be described later, are not provided. The configuration of upper metal sheet 820 will be described in more detail below.

As shown in FIGS. 3 and 5, the upper metal sheet 820 has upper steam channel recesses 822 provided in the lower surface 820a. The upper steam flow passage concave portion 822 constitutes a part of the sealed space 808 and is mainly configured so that the steam generated in the evaporating portion 811 passes through and cools the steam. More specifically, the steam in the upper steam channel recess 822 diffuses away from the evaporator 811, and most of the steam is transported to the relatively low-temperature periphery. Further, as shown in FIG. 3, on the upper surface 820b of the upper metal sheet 820 is arranged a housing member H that constitutes a part of the housing of a mobile terminal or the like. As a result, the steam in the upper steam passage recess 822 is cooled by the outside air through the upper metal sheet 820 and the housing member H.

2 and 5, upper channel walls 823, upper peripheral walls 824, and upper alignment holes 825 of upper metal sheet 820 are aligned with corresponding lower channel walls 813, 813, of lower metal sheet 810. They are arranged so as to overlap the lower peripheral edge wall 814 and the lower alignment hole 815 in plan view, thereby improving the mechanical strength of the vapor chamber 800 . The width and height of the upper channel wall portion 823 are preferably the same as the width and height h0 of the lower channel wall portion 813 described above.

Such lower metal sheet 810 and upper metal sheet 820 are permanently bonded together, preferably by diffusion bonding. More specifically, lower peripheral wall 814 and upper peripheral wall 824 are joined together. As a result, a sealed space 808 is formed between the lower metal sheet 810 and the upper metal sheet 820 in which the hydraulic fluid 807 is sealed. Also, each lower channel wall portion 813 and the corresponding upper channel wall portion 823 are joined to each other. This improves the mechanical strength of the vapor chamber 800 .

In addition, as shown in FIG. 2 , the vapor chamber 800 further includes an injection part 809 for injecting a hydraulic fluid 807 into the sealed space 808 at one of the pair of ends in the longitudinal direction. The injection part 809 has a lower injection projection 816 projecting from the end surface of the lower metal sheet 810 and an upper injection projection 826 projecting from the end surface of the upper metal sheet 820 . A lower injection channel recess 817 is formed on the upper surface of the lower injection projection 816 , and an upper injection channel recess 827 is formed on the lower surface of the upper injection projection 826 . The lower injection channel recess 817 communicates with the lower steam channel recess 812 , and the upper injection channel recess 827 communicates with the upper steam channel recess 822 . Lower injection channel recess 817 and upper injection channel recess 827 form injection channels for hydraulic fluid 807 when lower metal sheet 810 and upper metal sheet 820 are joined.

As shown in FIG. 4, the upper surface 813a of each lower flow path wall portion 813 is provided with a lower liquid flow path recess 818 through which the liquid working fluid 807 passes. The lower liquid flow channel recess 818 forms part of the sealed space 808 described above, and communicates with the lower steam flow channel recess 812 and the upper steam flow channel recess 822 described above. The lower liquid flow path recess 818 is mainly configured to transport the working liquid 807 condensed from the vapor generated in the evaporator 811 to the evaporator 811 . In this example, the lower liquid flow channel recessed portion 818 extends in an elongated shape along the longitudinal direction of the lower flow channel wall portion 813 (horizontal direction in FIG. 3). It extends from one end to the other end in the longitudinal direction of the channel wall portion 813 . In this manner, the liquid working fluid 807 condensed at the peripheral edge of the lower steam channel recess 812 and the peripheral edge of the upper steam channel recess 822 is transported to the evaporator 811 by capillary action. A plurality of lower liquid flow channel recesses 818 are formed on the upper surface 813a of one lower flow channel wall portion 813, and the respective lower liquid flow channel recesses 818 are spaced apart at regular intervals and parallel to each other. are placed. Although not shown, each of the lower liquid flow channel recesses 818 communicates with the lower steam flow channel recesses 812 also in the evaporating section 811 .

Materials used for the lower metal sheet 810 and the upper metal sheet 820 are not particularly limited as long as they have good thermal conductivity. It is preferable that it is made of an 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 enhanced. However, it is not limited to the above, and may be a metal material in which different metals are laminated, such as a clad material (SUS/Cu rolled laminated material) or a plated material (SUS/Cu plating, Ni plating/rolled copper). . In these cases, the strength can be increased compared to the case of forming from copper or a copper alloy. Moreover, 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, the thickness T1 of the lower metal sheet 810 and the thickness T2 of the upper metal sheet 820 are not limited to this. The thicknesses T2 need not be equal.

(Second embodiment)
By the way, 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), it may be difficult to read the optical identification structure 101 . The reason for this is that the boundaries (grain boundaries) of the crystal grains of the metal material forming 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) are optical identification structures. This is thought to be due to the inhibition of 101 reading. As the crystal grains become larger due to the heating during diffusion bonding, the crystal grain boundaries also become clear, and it is thought that fine unevenness due to the grain boundaries hinders reading in the surface layer.

The second embodiment addresses the problem of difficulty in reading the optical identification structure 201 acting as an ID due to the grain boundaries. 2nd Embodiment of this invention is described using FIG.6 and FIG.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) with an underlying layer 204 interposed therebetween. As shown in the top view of FIG. 6A and FIG. 7, the underlying layer 204 is formed in the underlying layer forming region 203 . The base layer forming area 203 is an area that matches the area where the optical identification structure 201 exists, or an area that includes the matching area and its surrounding area. The base layer formation region 203 coincides with the region where the optical identification structure 201 is present at the minimum, and at the maximum, as shown in FIG. The entire lower surface 210b) of the lower metal sheet 210. FIG. In other words, the base layer forming region 203 may include a region that matches the region where the optical identification structure 201 is present in plan view. (process time, material cost), etc. may be appropriately determined.

FIG. 6B shows a partial cross section of the vapor chamber 200 (upper metal sheet 220) cut in the lateral direction at the portion of the upper metal sheet 220 where the optical identification structure 201 acting as an ID is formed. A conceptual diagram is shown. Since FIG. 6(b) is a conceptual cross-sectional view, the positions of the optical identification structure 201 and the upper vapor channel recess 222 are different from the top view of FIG. 6(a). there is As conceptually shown in FIG. 6B, the base layer 204 is formed so as to cover the fine irregularities caused by the boundaries of crystal grains (crystal grain boundaries) of the metal material forming the upper surface 220b of the upper metal sheet 220. Therefore, the surface of the underlying layer 204 on which the optical identification structure 201 is formed (the upper surface of the underlying layer 204 in FIG. 6B) is hardly affected by the fine unevenness.

The underlayer 204 is not particularly limited as long as it has a function of reducing the problem that the crystal grain boundary hinders reading when reading the optical identification structure 201. However, in reading, A larger difference from the optical identification structure 201 is preferable. In other words, any material may be used as long as it has a function of making it difficult to recognize the crystal grain boundary during reading, and it is preferable that the difference from the optical identification structure 201 is large. As an example of the base layer 204 , a monochromatic printing ink having a large contrast with respect to the optical identification structure 201 is uniformly formed in the base layer 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 reading hindrance factor due to the crystal grain boundaries is reduced, and the contrast between the printing ink and the optical identification structure 201 is reduced. The large difference improves the readability of the optical identification structure 201 formed on the printing ink. In addition, since the printing ink is formed uniformly (so-called solid) without any pattern, it is possible to prevent the printing ink from interfering with the readability of the optical identification structure 201 .

The method of forming the base layer 204 using the printing ink is not particularly limited as long as it can be formed on the surface of the upper metal sheet 220 (upper surface 220b) or the surface of the lower metal sheet 210 (lower surface 210b). It is printed by With the inkjet method, printing can be easily performed even after the upper metal sheet 220 or the lower metal sheet 210 is separated into individual pieces. Offset printing, gravure printing, screen printing, etc. are also possible as long as it is in a roll state or a sheet state before being singulated. Although the case where the base layer 204 is printing ink has been described above, the present invention is not limited to this. What is suitable for the underlayer 204 depends largely on how the optical identification structure 201 is read. The underlying layer 204 may be formed by sublimation transfer, vapor deposition, sputtering, or other methods.

In this embodiment, an optical identification structure 201 is formed on the surface of the vapor chamber 200 with an underlying layer 204 interposed therebetween. Therefore, when the optical identification structure 201 is read, the problem that the crystal grain boundaries impede reading can be alleviated, and readability is improved. Therefore, the defective vapor chamber 200 can be identified more reliably. By suppressing the outflow of defective products, stable quality control becomes possible, and the vapor chamber 200 of good quality can be provided. Therefore, even in an electronic device in which the vapor chamber 200 of the present invention is mounted, heat radiation failure is suppressed, so that failure of the electronic device can be suppressed. Further, the position of the optical identification structure 201 makes it easy to distinguish between the front and back and top and bottom of the vapor chamber 200, which facilitates process management.

(Third embodiment)
Next, a third embodiment will be described. In the form in which the underlying layer 204 is formed as described in the second embodiment, it is often unnecessary to form the optical identification structure 201 in the peripheral region (the region where the upper peripheral wall 224 exists). This is probably because the underlying layer 204 often solves the conventional problem that the contour shape of the upper vapor passage concave portion 222 adversely affects the reading of the optical identification structure 201 as a background pattern. .

As shown in FIGS. 8A and 8B, in the third embodiment, if the optical identification structure 301 acting as an ID is formed through the base layer 304, it is not formed in the peripheral region. I don't mind. FIG. 8(a) is a top view, and FIG. 8(b) shows the vapor chamber 300 (upper metal sheet 320) in the portion of the upper metal sheet 320 where the optical identification structure 301 acting as an ID is formed. It is a partial cross-sectional conceptual diagram at the time of cutting|disconnecting in a transversal direction. Since FIG. 8(b) is a diagram showing a conceptual cross section, the positions of the optical identification structure 301 and the upper vapor channel recess 322 are different from the top view of FIG. 8(a). there is As conceptually shown in FIG. 8B, especially when the base layer 304 is thick, the surface of the vapor chamber 300 (the upper surface 320b of the upper metal sheet 320 or the lower surface 310b of the lower metal sheet 310) , the surface of the base layer 304 (the base layer 304 is the surface of the vapor chamber 300 (the surface of the upper metal sheet 320 On the surface opposite to the surface in contact with the upper surface 320b), the irregularities of the contour shape of the upper steam flow channel recess 322 (lower steam flow channel recess 312) hardly appear. That is, in the third embodiment, the underlying layer 304 also has the effect of flattening the target surface on which the optical identification structure 301 is formed.

In the third embodiment, as in the second embodiment, the base layer formation region 303 only needs to include a region that coincides with the region where the optical identification structure 301 exists in plan view, as shown in FIG. Alternatively, it may be formed on the entire surface of vapor chamber 300 (upper surface 320b of upper metal sheet 320 or lower surface 310b of lower metal sheet 310). Also, the method of forming the base layer 304 is the same as that exemplified in the second embodiment.

The third embodiment also has the effects described in the second embodiment. In addition, since the optical identification structure 301 does not need to be formed in the peripheral area in the third embodiment, the degree of freedom of the formation position of the optical identification structure 301 is improved. As a result, it is possible to reduce restrictions on the installation position and the like of the device that forms the optical identification structure 301 and the device that reads it.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. In the fourth embodiment, the optical identification structure 401 acting as an ID is a portion of 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) having an internal space, It is formed on a smooth surface with a height difference of 30 μm or less in a portion without an internal space. As shown in the top view of FIG. 9A and FIG. 10, the smooth surface is formed in the smooth surface forming region 405 . The smooth surface forming area 405 is an area that coincides with the area where the optical identification structure 401 exists, or an area obtained by adding the surrounding area to the corresponding area. The smooth surface forming area 405 coincides with the area where the optical identification structure 401 exists in the smallest case, and the surface of the vapor chamber 400 (upper surface 420b of the upper metal sheet 420, the upper surface 420b of the upper metal sheet 420, Alternatively, the entire lower surface 410 b) of the lower metal sheet 410 . That is, the smooth surface forming area 405 may include an area that matches the area where the optical identification structure 401 is present in plan view, and the readability of the optical identification structure 401 and the load that forms the smooth surface ( process time), etc., and may be appropriately determined. At this time, it is desirable that the maximum height roughness Rz is 1 μm or less.

FIG. 9B is a partial cross section of the vapor chamber 400 (upper metal sheet 420) cut in the lateral direction at the portion of the upper metal sheet 420 where the optical identification structure 401 acting as an ID is formed. A conceptual diagram is shown. Since FIG. 9(b) is a diagram showing a conceptual cross section, the positions of the optical identification structure 401 and the upper vapor channel recess 422 are different from the top view of FIG. 9(a). there is As conceptually shown in FIG. 9(b), fine unevenness caused by the boundaries of crystal grains (crystal grain boundaries) of the metal material forming the upper surface 420b of the upper metal sheet 420 and the upper vapor flow channel recessed portions 422 are formed. The influence of the formed influence reaching the upper surface 420b of the upper metal sheet 420 is greatly reduced by the formation of the smooth surface. That is, by forming a smooth surface, the maximum height roughness Rz is 1 μm or less, and the height difference between a portion with an internal space and a portion without an internal space is 30 μm or less.

The above smooth surface formed in the smooth surface forming region 405 can be formed, for example, by polishing the surface of the upper metal sheet 420 (upper surface 420b) or the surface of the lower metal sheet 410 (lower surface 410b). . Any of chemical polishing, electrolytic polishing, and mechanical polishing can be applied 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 emery paper, buffing with alumina abrasive grains or the like may be performed to change the grain size of the abrasive grains. 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 portion with the internal space and the portion without the internal space is 30 μm or less.

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

Also, 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. Using a laser microscope (Keyence Corporation, VK-X250), the direction of measurement is the longitudinal direction of the vapor chamber 400 in plan view (horizontal direction in FIG. 9). The direction perpendicular to the upper flow path wall portion 423 (the lateral direction of the vapor chamber 400 in plan view (vertical direction in FIG. 9)) is preferable. With a laser wavelength of 408 nm, an objective lens of 100 or 150 times, and other parameters appropriately set, the maximum height roughness Rz of the smooth surface forming region 405 can be measured.

In the fourth embodiment, the optical identification structure 401 is formed 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 an internal space and without an internal space. Since the portion is formed on a smooth surface with a height difference of 30 μm or less, the above-mentioned problem that the contour shape of the upper steam flow channel recessed portion 422 adversely affects the reading of the optical identification structure 401 as a background pattern can be greatly reduced. can be suppressed. Therefore, unlike the first embodiment, the optical identification structure 401 need not be formed in the peripheral region (the region where the upper peripheral wall 424 exists), and can be formed at any position as in the third embodiment. can.

Further, when one side of the printed area is 1 mm or more and 3 mm or less in the laser printing method, a smooth surface having a maximum height roughness Rz of 1 μm or less can be obtained. This polishing makes it possible to reduce fine dents caused by the crystal grain boundaries compared to the surface before polishing, and significantly solves the problem that the crystal grain boundaries adversely affect the reading of the optical identification structure 401 as a background pattern. can be suppressed.

Due to the above effect, the defective vapor chamber 400 can be reliably identified also in the fourth embodiment. By suppressing the outflow of defective products, stable quality control becomes possible, and the vapor chamber 400 of good quality can be provided. Therefore, even in an electronic device in which the vapor chamber 400 of the present invention is mounted, heat radiation failure is suppressed, so that failure of the electronic device can be suppressed. In addition, the position of the optical identification structure 401 facilitates distinguishing between the front and back and top and bottom of the vapor chamber 400, thereby facilitating process control.

In the smooth surface of the fourth embodiment, both 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. is preferred. However, it does not matter if only one of them is satisfied. That is, if the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less, it is possible to obtain the above-described effect that the adverse effect due to the contour shape of the upper steam flow passage concave portion 422 can be greatly suppressed. If the maximum height roughness Rz is 1 μm or less, it is possible to obtain the above-described effect that the adverse effects of grain boundaries can be greatly suppressed.

Next, an outline of an example of a method for manufacturing the vapor chamber 400 according to the fourth embodiment will be described. The manufacturing method of the vapor chamber 400 in the fourth embodiment includes a step of polishing a portion for forming an optical identification structure 401 acting as an ID, and forming the optical identification structure 401 acting as an ID on the polished portion. and at least in this order. FIG. 11 shows a conceptual partial cross-sectional view of a process characteristic of the fourth embodiment in one example of the method of manufacturing the vapor chamber 400 according to the fourth embodiment. FIG. 11 is a conceptual partial cross-sectional view when the vapor chamber 400 (upper metal sheet 420) is cut in the lateral direction at the portion of the upper metal sheet 420 where the optical identification structure 401 acting as an ID is formed. There is, in fact, joined to the lower metal sheet 410, but only the upper metal sheet 420 is shown.

As an example, first, a lower metal sheet 410 in which the lower steam channel recess 412 and the lower liquid channel recess 418 are formed, and an upper metal sheet 420 in which the upper steam channel recess 422 is formed are prepared.

In this case, first, a resist film R is formed on the upper surface of the metal material sheet M. As shown in FIG. For the resist film R, an electrodeposition resist material that can be adhered by an electric field can be preferably used. may

Subsequently, the resist film R is patterned. In the case of the lower metal sheet 410, resist openings corresponding to the lower vapor channel recesses 412 and resist openings corresponding to the lower liquid channel recesses 418 are formed in the resist film R by photolithography. be.

Subsequently, as a half-etching step, the opening portion of the resist film R is half-etched to form the lower steam channel recess 412 , the lower channel wall 413 and the lower peripheral wall 414 . At this time, a lower liquid flow path concave portion 418 is formed on the upper surface 413 a of the lower flow path wall portion 413 . 2 and 4 are also formed at the same time, and the metal material sheet M is etched from the upper and lower surfaces so as to have the contour shape shown in FIG. is obtained. Note that half-etching means etching for forming recesses that do 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 . As the etchant, for example, an iron chloride-based etchant such as an aqueous ferric chloride solution or a copper chloride-based etchant such as an aqueous copper chloride solution can be used.

After that, the resist film R is removed to obtain the lower metal sheet 410 in which the lower steam channel recess 412, the lower channel wall 413, the lower peripheral wall 414 and the lower liquid channel recess 418 are formed. .

On the other hand, 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 an upper steam channel recess 422, an upper channel wall 423 and an upper peripheral wall 424. Thus, the upper metal sheet 420 described above is obtained.

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

In this case, first, 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, Metal sheet 410 and upper metal sheet 420 are aligned. Subsequently, the lower metal sheet 410 and the upper metal sheet 420 are temporarily fixed. Although the method of temporary fixing is not particularly limited, for example, the lower metal sheet 410 and the upper metal sheet 420 are temporarily joined by resistance welding. You can stop. In this manner, the lower metal sheet 410 and the upper metal sheet 420 are temporarily fixed while being aligned.

After temporary fixing, the lower metal sheet 410 and the upper metal sheet 420 are permanently joined by diffusion bonding (FIG. 11(a)). In the diffusion bonding, the lower metal sheet 410 and the upper metal sheet 420 to be bonded are brought into close contact, and pressure is applied in a controlled atmosphere such as a vacuum or an inert gas in a direction to bring the metal sheets 410 and 420 into close contact. It is a method of bonding by heating together and utilizing diffusion of atoms occurring on the bonding surface. Diffusion bonding heats the material of the lower metal sheet 410 and the upper metal sheet 420 to a temperature close to, but below the melting point, thus avoiding melting and deformation of each metal sheet 410, 420.

Next, the portion where the optical identification structure 401 is to be formed is polished. That is, on either the upper surface 420b of the upper metal sheet 420 or the lower surface 410b of the lower metal sheet 410 or the entire surface of both surfaces, 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 is 30 μm or less. Chemical polishing is performed so that the roughness Rz is 1 μm or less. FIG. 11B shows an example of chemically polishing the entire surface. If the smooth surface forming region 405 is not the entire surface, chemical polishing is performed after masking the region other than the smooth surface forming region 405 with a resist or the like. Do it. The chemical polishing liquid may be appropriately selected from nitric acid-sulfuric acid-hydrochloric acid polishing liquid (commonly known as Kirin's liquid), hydrogen peroxide-sulfuric acid polishing liquid, phosphoric acid polishing liquid, and the like. 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.

Next, an optical identification structure 401 is formed on the polished portion. That is, the optical identification structure 401 is formed in 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 capable of optically reading numbers, letters, symbols, two-dimensional codes such as QR codes, or bar codes. It is read optically by a device such as a scanner or a reader, or visually. The optical identification structure 401 is often formed by printing by an inkjet method, laser printing, engraving, or the like. As an example, a QR code is printed with an inkjet printer. The ID information possessed by the formed optical identification structure 401 is individually different. The ID information is used for lot management, atmospheric pressure conditions when injecting the fluid responsible for heat transport, inspection results for the injection amount of the fluid, and the vapor chambers in the process of formation, so as to be clearly distinguished from each other. be done.

Next, the sealed space 408 is depressurized, and then the working fluid 407 is injected into the sealed space 408 from the injection channel formed by the lower injection channel recess 417 and the upper injection channel recess 427 . The working fluid 407 is, for example, pure water. After that, for example, the injection part 409 is irradiated with a laser to partially melt the injection part 409 to seal the injection channel. The vapor chamber 400 is thus completed.

As an example of utilizing the optical identification structure 401 in the above process, in the step of injecting the working liquid 407 and sealing, the optical identification structure 401 (QR code) is read with a scanner, and the vapor chamber 400 is changed. Each vapor chamber 400 is associated with the amount of hydraulic fluid 407 that may be injected and the measured value of the pressure in the sealed space 408 at the time of sealing. When the optical identification structure 401 (QR code) is read by the scanner, the entire surface on which the optical identification structure 401 is formed is polished to be a smooth surface.

On the smooth surface, the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less. Therefore, it is possible to greatly suppress the problem that the contour shape of the upper steam flow channel concave portion 422 adversely affects the reading of the optical identification structure 401 as a background pattern.

Moreover, on a smooth surface, the maximum height roughness Rz is 1 μm or less. Therefore, it is possible to greatly suppress the above-mentioned problem that the crystal grain boundary adversely affects reading of the optical identification structure 401 as a background pattern.

Also in the process example described above, the defective vapor chamber 400 can be reliably identified due to the effects described above. By suppressing the outflow of defective products, stable quality control becomes possible, and the vapor chamber 400 of good quality can be provided. Therefore, even in an electronic device in which the vapor chamber 400 of the present invention is mounted, heat radiation failure is suppressed, so that failure of the electronic device can be suppressed. In addition, the position of the optical identification structure 401 facilitates distinguishing between the front and back and top and bottom of the vapor chamber 400, thereby facilitating process control.

Although each embodiment has been described above, the present invention is not limited to each of the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

100, 200, 300, 400, 800, 900 vapor chamber 101, 201, 301, 401, 901 optical identification structure 203, 303 base layer formation region 204, 304 base layer 405 smooth surface formation region 407, 807 working liquid 408 , 808 sealed space 409, 809 injection part 110, 210, 310, 410, 810, 910 lower metal sheet 810a upper surface 110b, 210b, 310b, 410b, 810b, 910b lower surface 811 evaporator 112, 312, 412, 812 lower side Steam channel recess 812a Bottom surface 413, 813 Lower channel wall 413a, 813a Upper surface 114, 414, 814 Lower peripheral wall 415, 815 Lower alignment hole 816 Lower injection protrusion 417, 817 Lower injection channel recess 418, 818 Lower liquid flow path concave portion 120, 220, 320, 420, 820, 920 Upper metal sheet 420a, 820a Lower surface 120b, 220b, 320b, 420b, 820b, 920b Upper surface 122, 222, 322, 422, 822, 922 Upper steam channel recess 423, 823, 923 Upper channel wall 823a Lower surface 124, 224, 424, 824, 924 Upper peripheral wall 425, 825 Upper alignment hole 826 Upper injection protrusion 427, 827 Upper injection channel recess D Device H housing member M metal material sheet R resist film

Claims (8)

A flat vapor chamber having therein a fluid channel responsible for heat transport,
In plan view, having a channel region in which the channel is formed and a peripheral edge region surrounding the channel region,
A vapor chamber in which an optical identification structure acting as an ID is formed in said peripheral region. 2. The vapor chamber according to claim 1, wherein the optical identification structure acting as the ID is formed through an underlying layer. A flat vapor chamber having therein a fluid channel responsible for heat transport,
A vapor chamber in which an optical identification structure acting as an ID is formed through an underlying layer. A flat vapor chamber having therein a fluid channel responsible for heat transport,
A vapor chamber in which an optical identification structure acting as an ID is formed independently of the flow path and formed on a smooth surface having a maximum height roughness Rz of 1 μm or less. A flat vapor chamber having therein a fluid channel responsible for heat transport,
A vapor chamber 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 a portion with an internal space and a portion without an internal space. A method for manufacturing a planar vapor chamber having therein a fluid flow path responsible for heat transport and an optical identification structure acting as an ID is formed,
polishing a portion forming an optical identification structure acting as the ID;
and forming an optical identification structure acting as the ID on the polished portion. 7. The method of manufacturing a vapor chamber according to claim 6, wherein the step of polishing the portion forming the optical identification structure acting as the ID is a step of polishing so that the maximum height roughness Rz is 1 μm or less. . 3. The step of polishing the portion forming the optical identification structure acting as the ID is a step of polishing so that the height difference between the portion with the internal space and the portion without the internal space is 30 μm or less. The method for manufacturing the vapor chamber according to claim 6 or claim 7.

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