Boiling acceleration section and vapor chamber

Abstract

The present invention provides a boiling acceleration unit and a vapor chamber that can improve the boiling acceleration effect. [Solution] The boiling acceleration unit 1 comprises a base portion 2 and a plurality of fins 3 erected from the base portion 2. Each fin 3 has a main body portion 32 extending perpendicularly to the base portion 2 and an inclined portion 31 that is inclined relative to the main body portion 32 at the connection point with the base portion 2, and its entire surface is pear-skin shaped.

Description

[Technical Field]

[0001] This invention relates to a boiling acceleration unit and a vapor chamber. [Background technology]

[0002] Conventionally, a boiling transfer surface for a boiling cooler has been proposed in which the tip of a fin is bent and joined to an adjacent fin, and a small hole is formed at the top (see, for example, Patent Document 1). In the boiling transfer surface described in Patent Document 1, a cavity is formed between adjacent fins, making it easier for bubble nuclei to be generated within the cavity. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-75563 [Overview of the project] [Problems that the invention aims to solve]

[0004] In structures that promote boiling by forming cavities, the heat transfer coefficient can be increased by increasing the density of the cavities. However, in structures like the one described in Patent Document 1, the upper limit of the number of cavities is determined by the number of fins, making it difficult to achieve a density above a certain level, and further improvement of the boiling promotion effect was desired.

[0005] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a boiling acceleration unit and a vapor chamber that can improve the boiling acceleration effect. [Means for solving the problem]

[0006] To achieve the above objective, the boiling-promoting unit according to the present invention comprises a base portion and a plurality of fins erected from the base portion, wherein each fin has a main body portion extending perpendicularly to the base portion and an inclined portion that is inclined relative to the main body portion at the connection portion with the base portion, and its entire surface is pear-skin shaped.

[0007] In one aspect of the present invention, the boiling-promoting unit has a base that is formed in a plate shape and has a thickness of 0.5 mm or more.

[0008] A boiling-promoting unit according to one aspect of the present invention has a base portion comprising a fin arrangement region on which the fins are provided, and an edge portion formed around the fin arrangement region.

[0009] In one embodiment of the present invention, the boiling-promoting unit has a surface roughness Ra of 0.5 μm or more on the pear-skin surface of the fins.

[0010] In one aspect of the present invention, the boiling-promoting section is configured such that a plurality of fins are arranged in the direction of the plate thickness to form a fin group, and the plurality of fin groups are arranged in the direction in which the fins extend along the base portion.

[0011] In one aspect of the present invention, the boiling-promoting section has the base section and the plurality of fins formed integrally.

[0012] In one aspect of the present invention, the boiling-promoting section has a plurality of fins whose height decreases as they move toward one side in the direction extending along the base section.

[0013] In one aspect of the present invention, the boiling-promoting section has a plurality of fins with heights of 0.5 mm or more and 20 mm or less.

[0014] In one aspect of the present invention, the boiling-promoting section has a thickness of 1 mm or less for the plurality of fins.

[0015] To achieve the above object, the vapor chamber according to the present invention includes a vapor chamber body that is thermally connected to a heat source, and the boiling promotion part described above, and a soldering part for connecting the vapor chamber body and the boiling promotion part is provided.

[0016] To achieve the above object, the vapor chamber according to the present invention includes a vapor chamber body that is thermally connected to a heat source, and the boiling promotion part according to claim 1, and a welding part for connecting the vapor chamber body and the boiling promotion part is provided.

Effect of the Invention

[0017] According to the boiling promotion part and the vapor chamber according to the present invention, the boiling promotion effect can be improved.

Brief Description of the Drawings

[0018] [Figure 1] It is a side view schematically showing a cooling system provided with a boiling promotion part according to a first embodiment of the present invention. [Figure 2] It is a perspective view showing a boiling promotion part according to a first embodiment of the present invention. [Figure 3] It is a cross-sectional view showing a boiling promotion part according to a first embodiment of the present invention. [Figure 4] It is a perspective view showing a boiling promotion part according to a second embodiment of the present invention. [Figure 5] It is a perspective view showing a boiling promotion part according to an example and a modification of the present invention. [Figure 6] It is a graph showing the relationship between the heat flux and the heat transfer coefficient of the boiling promotion part according to an example and a modification of the present invention. [Figure 7] It is a graph showing the heat transfer coefficient when the heat flux of the boiling promotion part according to an example and a modification of the present invention is 25 W / cm2. [Figure 8] It is a graph showing the heat transfer coefficient at the critical heat flux point or the heat transfer coefficient reduction point of the boiling promotion part according to an example and a modification of the present invention. [Figure 9]This graph shows the heat transfer coefficient of the boiling acceleration section at a heat flux of 48 W / cm2 according to embodiments and modifications of the present invention. [Modes for carrying out the invention]

[0019] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic side view showing a cooling system 220 equipped with a boiling promotion unit 1 according to the first embodiment of the present invention, Figure 2 is a perspective view showing the boiling promotion unit 1, and Figure 3 is a cross-sectional view showing the boiling promotion unit 1.

[0020] As shown in Figures 1 to 3, the boiling accelerating unit 1 according to the first embodiment of the present invention comprises a base portion 2 and a plurality of fins 3 erected from the base portion 2. Each fin 3 has a main body portion 32 extending perpendicularly to the base portion 2 and an inclined portion 31 that is inclined relative to the main body portion 32 at the connection portion with the base portion 2, and its entire surface is pear-skin shaped.

[0021] The vapor chamber 10 comprises a vapor chamber body 11 that is thermally connected to a heat source 100, and a boiling accelerator 1. The vapor chamber body 11 and the boiling accelerator 1 are connected by a connecting portion 12, which is a soldered portion formed by soldering, or a welded portion formed by welding (preferably laser welding).

[0022] The vapor chamber 10 can be used in a cooling system 220, for example, as shown in Figure 1. The cooling system 220 comprises a cooling device 210 and a secondary refrigerant cooling section 221 to which a condensing pipe 204 extending from the cooling device 210 is connected, and a liquid-phase secondary refrigerant 202 flowing through the condensing pipe 204 circulates between the cooling device 210 and the secondary refrigerant cooling section 221. The cooling device 210 has a liquid-phase primary refrigerant 201 sealed and stored inside a container 200, and a condensing pipe 204 through which the liquid-phase secondary refrigerant 202 flows, penetrating a gas phase section 203 inside the container 200, and a heat source 100 is immersed in the liquid-phase primary refrigerant 201 sealed inside the container 200. When the vapor chamber 10 is immersed in the liquid-phase primary refrigerant 201, it is thermally connected to the heat source 100 which is immersed in the liquid-phase primary refrigerant 201.

[0023] The vapor chamber body 11 comprises a container with a cavity formed inside, a working fluid sealed in the cavity, and a vapor passage provided in the cavity through which the gaseous working fluid flows. The container is a thin, plate-shaped container.

[0024] The vapor chamber body 11 has a plate portion 111 extending along a predetermined plane and a protrusion 112 projecting from one surface of the plate portion, with a boiling accelerator 1 provided on the other surface of the plate portion 111. The vapor chamber body 11 is thermally connected to the heat source 100 by the protrusion 112 contacting the heat source 100. The internal space of the plate portion 111 and the internal space of the protrusion 112 are in communication with each other, forming a cavity in the container. The vapor chamber 10, equipped with such a vapor chamber body 11 and boiling accelerator 1, is a flat-type heat pipe.

[0025] The boiling-promoting section 1 comprises a base section 2 and a plurality of fins 3 integrated into one unit. The boiling-promoting section 1 is formed from a metal such as copper or a copper alloy, and the base section 2 and the fins 3, which are skived fins, are integrally formed by skiving the metal block.

[0026] As shown in Figure 2, the base portion 2 is formed in the shape of a rectangular plate, with fins 3 provided on one surface 2A, and the other surface 2B serving as a connecting surface to the plate portion 111 of the vapor chamber body 11. The above-mentioned connecting portion 12 is provided between the other surface 2B and the plate portion 111. From the viewpoint of workability when skiving, the thickness (plate thickness) of the base portion 2 is preferably 0.5 mm or more.

[0027] The fin 3 is formed in a plate shape that is erected from the base portion 2 and has a main body portion 32 and an inclined portion 31. The main body portion 32 extends perpendicularly or substantially perpendicularly to the plate-shaped base portion. The inclined portion 31 is provided at the connection point between the base portion 2 and the fin 3 and is inclined with respect to the main body portion 32. That is, the inclined portion 31 is inclined with respect to a direction perpendicular to the base portion 2. Thus, the fin 3 has a shape that protrudes from the base portion 2 inclined with respect to a vertical direction and then extends along that vertical direction. The inclination angle of the inclined portion 31 with respect to the main body portion 32 (the inclination angle with respect to a direction perpendicular to the base portion 2) is preferably, for example, 40 to 50°.

[0028] In the following explanation, for the sake of clarity, the direction along the base portion 2 of the plate-shaped fin 3 will be referred to as the extension direction of the fin 3, and the direction perpendicular to the base portion 2 will be referred to as the protrusion direction of the fin 3. Furthermore, the direction in which multiple fins 3 are aligned will be referred to as the parallel direction.

[0029] As a result of the inclined portion 31 described above, a triangular cross-sectional opposing space S1 is formed in the boiling promotion section 1 on the acute-angle side between the base section 2 and the inclined portion 31. The opposing space S1 is a region enclosed by one surface 2A of the base section 2, the acute-angle side surface of the inclined portion 31, and a line that virtually extends the main body section 32 toward the surface 2A.

[0030] The surface of fin 3 is given a textured finish, so that the entire surface of fin 3 is textured. A preferred method for applying the textured finish is, for example, wet etching, but sandblasting or sintering of metal powder (copper powder) may also be used. The surface roughness Ra of the textured surface can be appropriately selected depending on the operating conditions of the boiling accelerator 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. The surface roughness Ra of the textured surface is preferably 0.5 μm or more, as this creates fine cavities in the textured surface, facilitating the formation of boiling nuclei, as will be described later.

[0031] In particular, the main body portion 32 of the fin 3 extends along the long side direction of the rectangular base portion 2, and multiple fins 3 are arranged along the short side direction of the base portion 2. That is, the main body portion 32 of the fin 3 extends along a plane that includes both the long side direction of the base portion 2 and the direction perpendicular to the base portion 2.

[0032] The base portion 2 has a fin arrangement region 2C on one of its surfaces 2A, on which fins 3 are provided, and an edge portion 2D formed around the fin arrangement region 2C. The fin arrangement region 2C is formed in a rectangular shape. The edge portion 2D is an area where fins 3 are not provided, and is formed in a rectangular frame shape so as to surround the fin arrangement region 2C.

[0033] The vapor chamber 10 is installed in the cooling system 220 in such an orientation that the plate portion 111 of the vapor chamber body 11 and the base portion 2 of the boiling accelerator 1 extend along the vertical direction. In this case, the rectangular plate portion 111 and the base portion 2 are oriented so that their longer sides are aligned with the vertical direction. As a result, the multiple fins 3 are aligned along one direction in the horizontal plane, and the fins 3 extend along the vertical direction.

[0034] Here, the boiling and evaporation of the liquid-phase primary refrigerant 201 in the boiling acceleration unit 1 will be described. First, the heat generated from the heat source 100 is transferred to the boiling acceleration unit 1 via the vapor chamber body 11. In the boiling acceleration unit 1, heat conduction occurs from the base unit 2 to each of the multiple fins 3, and heat is mainly transferred from the surface of the fins 3 to the primary refrigerant 201, causing evaporation.

[0035] In this case, the opposing space S1 is formed by the inclined portion 31 as described above, and this opposing space S1 becomes a cavity, which contributes to promoting boiling and enables high heat transfer. In particular, the heat output of the heat source 100 is large and is likely to contribute to promoting boiling at high heat flux.

[0036] In the fins 3, at positions away from the base portion 2 (for example, at positions 1 mm or more away), the degree of superheating is lower compared to the opposing space S1 and its vicinity. However, because the surface of the fins 3 is a textured surface, the irregularities in the textured surface act as fine cavities, promoting boiling.

[0037] As described above, the primary refrigerant 201 that has boiled and evaporated becomes a gas and its density decreases, causing it to flow upward in the vertical direction. Since the fins 3 extend along the vertical direction, the gaseous primary refrigerant 201 passes between adjacent fins 3 and is discharged along the fins 3 in an upward vertical direction. This discharge of primary refrigerant 201 creates an upward vertical fluid flow, and new liquid-phase primary refrigerant 201 is supplied between adjacent fins 3. Therefore, even at high heat flux, it is easy to keep the surface of the fins 3 wet, suppressing burnout and maintaining nucleate boiling.

[0038] Next, we will explain the details of the dimensions of each part of fin 3. As shown in Figures 2 and 3, let H be the height of fin 3 (dimension in the protruding direction), T be the thickness of fin 3 (dimension in the parallel direction), and G be the gap between adjacent fins 3 (distance in the parallel direction).

[0039] The height H of the fins 3 can be appropriately selected depending on the operating conditions of the boiling accelerator 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. As described above, in order to maintain the surface of the fins 3 in a wet state, the height H of the fins 3 is preferably 0.5 mm or more, more preferably 1 mm or more, and even more preferably 2 mm or more. Also, in order to reduce the portion of the fins 3 that is far from the base portion 2 and has a low degree of superheating, the height H of the fins 3 is preferably 15 mm or less, and more preferably 8 mm or less. In this embodiment, the vapor chamber 10 is composed of a vapor chamber body 11 in which a working fluid is sealed in a cavity and thermally connected to the heat source 100, and a boiling accelerator 1. However, the vapor chamber may be composed without a vapor chamber body by having the heat source in direct contact with the boiling accelerator. In such a configuration, in order to secure a heat transfer area and to increase the heat flux at the CHF point, which will be described later, the height H of the fins may be made relatively high, for example, to 20 mm or less. Furthermore, the height H of multiple fins 3 is the same, and the height H of the fins 3 does not change depending on their position in the extension direction and remains constant.

[0040] The gap G can be appropriately selected depending on the operating conditions of the boiling acceleration unit 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. The gap G is preferably 0.06 mm or larger, and more preferably 0.08 mm or larger, from the standpoint of improving the heat transfer coefficient by utilizing the uneven surface of the pear-textured surface as a cavity, and facilitating passage when the evaporation rate of the primary refrigerant 201 increases. Furthermore, the gap G is preferably 1 mm or smaller from the standpoint of ensuring the density of the opposing space S1 as a cavity and improving the heat transfer coefficient.

[0041] The thickness T can be appropriately selected depending on the operating conditions of the boiling accelerator 1 and the physical properties of the refrigerant in the liquid phase into which the heat source 100 is immersed. From the viewpoint of processability when cutting and raising the fins 3 by skiving, the thickness T is preferably 0.06 mm or more, and more preferably 0.08 mm or more. Furthermore, from the viewpoint of ensuring the density of the fins 3 and improving the heat transfer coefficient, the thickness T is preferably 1 mm or less.

[0042] According to the boiling-promoting unit 1 of the first embodiment of the present invention described above, the boiling-promoting effect can be improved because the fin 3 has an inclined portion 31 and the entire surface of the fin 3 is a pear-skin surface. That is, although there is an upper limit to the number of cavities formed by the inclined portion 31, cavities can also be formed by the pear-skin surface, and compared to a configuration in which cavities are formed only by the shape of the fins, it is easier to form boiling nuclei and improve the boiling-promoting effect.

[0043] Furthermore, even if the density of the fine cavities formed by the pear-shaped surface is increased, the spaces are partitioned by fin 3, preventing bubbles from merging within these partitioned spaces. This suppresses burnout caused by bubbles becoming larger.

[0044] Furthermore, the base portion 2 having an edge portion 2D in addition to the fin arrangement region 2C improves machinability when skiving and also improves workability when attaching to other parts (e.g., vapor chamber or heat source).

[0045] Furthermore, since the base portion 2 and the multiple fins 3 are integrally formed, the number of parts can be reduced, and heat can be easily transferred between the base portion 2 and the fins 3.

[0046] Furthermore, since the boiling acceleration unit 1 is connected to the vapor chamber body 11 by a connecting part 12 which is a soldering or welding part, the boiling acceleration unit 1 can be molded independently of the vapor chamber body 11 and then joined to the vapor chamber body 11, thereby improving processability.

[0047] [Second Embodiment] A second embodiment of the present invention will be described with reference to the drawings. Figure 4 is a perspective view showing the boiling promotion unit 4 according to the second embodiment of the present invention. In the following, components having the same shape or function as those in the first embodiment will be denoted by the same reference numerals as in the first embodiment and their descriptions will be omitted. The differences from the first embodiment will be described in detail.

[0048] The boiling-promoting section 4 according to the second embodiment has a base section 2 and a plurality of fins 5. The fins 5 have a main body section and an inclined section, similar to the first embodiment, and their entire surface is a pear-skin texture. The plurality of fins 5 form first to third fin groups 51 to 53. In each of the first to third fin groups 51 to 53, the plurality of fins 5 are arranged in the direction of their plate thickness. The first to third fin groups 51 to 53 are arranged in this order in a predetermined direction, and this direction of arrangement coincides with the extension direction (vertical direction) of each fin 5.

[0049] In other words, the fin 3 of the first embodiment is divided into three parts in its extending direction, which corresponds to the fin 5 of the second embodiment 5. The number of divisions (number of fin groups) is not particularly limited and may be two or four or more.

[0050] According to the boiling promotion unit 4 of the second embodiment of the present invention described above, similar to the boiling promotion unit 1 of the first embodiment, the fin 5 has a main body portion and an inclined portion, similar to the first embodiment, and its entire surface is pear-skinned, thereby improving the boiling promotion effect.

[0051] Furthermore, since multiple fin groups 51-53 are aligned in the direction of extension of the fin 5, the primary refrigerant 201 in the gas phase can be discharged between the fin groups 51-53. This ensures discharge even when the fins 5 are provided on the base portion 2 over a wide area in the direction of extension, or when the height of the fins 5 is high, and facilitates the generation of fluid flow toward the upward in the vertical direction.

[0052] Although embodiments of the present invention have been described above, the present invention is not limited to the boiling-promoting unit according to the above embodiments, but includes all embodiments included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention.

[0053] For example, in the above embodiment, the height H of the fin 3 was assumed to be constant and not change with respect to its position in the extending direction. However, the fin may have a slope such that the height H of the fin decreases as it moves toward one side in the extending direction of the fin. In this case, the boiling promotion section is provided in the cooling system in such a orientation that the height H of the fin decreases as it moves toward the upward side in the vertical direction. With such a configuration, even when the extension dimension of the fin is large, the discharge of the primary refrigerant can be ensured, and it is easy to generate a fluid flow toward the upward side in the vertical direction.

[0054] [Examples] Examples and comparative examples of the present invention will now be described. The boiling acceleration unit 6 in Examples 1 to 7 and Comparative Examples 1 to 7 has a base portion 2 and a plurality of fins 7, as shown in Figure 5, and the height H, thickness T, and gap G of the fins 7 differ from each other in Examples 1 to 7 and Comparative Examples 1 to 7. The boiling acceleration unit 6 was oriented so that the base portion 2 extends along the vertical direction, similar to the first and second embodiments, and the heat transfer coefficient with respect to the heat flux was measured by heating the other side 2B of the base portion 2 (the vapor chamber body 11 side) with a heater.

[0055] Table 1 shows the height H, thickness T, and gap G for Examples 1 to 7. In Examples 1 to 7, the entire surface of the fin 7 is textured, while in Comparative Examples 1 to 7, the surface of the fin 7 is not textured. The dimensions of the fin 7 in Comparative Examples 1 to 7 are the same as the dimensions of the fin 7 in Examples 1 to 7. That is, if the dimensions of the fin 7 in Examples 1 to 7 are conditions A to F, then Comparative Examples 1 to 7 correspond to conditions A to F, respectively. Comparative Example 8 is a boiling accelerator that uses three metal meshes with a mesh count of #350 pressed together instead of fins 7.

[0056] [Table 1]

[0057] Figure 6 shows the measurement results of the heat transfer coefficient with respect to heat flux for Examples 1-7 and Comparative Examples 1-8. Furthermore, for Examples 2, 3, 7 and Comparative Examples 1-8, the heat flux was 25 W / cm². 2 The heat transfer coefficient (kW / m²) in this case 2 Figure 7 shows K), where the heat transfer coefficient at the critical heat flux point (CHF) or the heat flux at which the heat transfer coefficient begins to decrease (heat transfer coefficient decrease point) is (kW / m 2 Figure 8 shows the heat flux (K), which is 48 W / cm². 2 The heat transfer coefficient (kW / m²) in this case 2 Figure 9 shows K). Detailed numerical values ​​for Figures 7-9 are shown in Tables 2-4. The improvement rates in Tables 2-4 are based on Comparative Example 8.

[0058] [Table 2]

[0059] [Table 3]

[0060] [Table 4]

[0061] [Heat flux is 25W / cm 2 [Comparison at the time] In Examples 1-7, an improvement in heat transfer coefficient was observed compared to Comparative Example 8. In Comparative Examples 1-7, with the exception of Comparative Example 2, no improvement in heat transfer coefficient was observed compared to Comparative Example 8. Furthermore, the improvement rates of Examples 1-7 compared to Comparative Example 8 were higher than the improvement rates of Comparative Examples 1-7 compared to Comparative Example 8. That is, the heat flux was 25 W / cm². 2 In this experiment, simply changing the boiling-promoting section from mesh to fins did not significantly improve the heat transfer coefficient. However, an improvement in the heat transfer coefficient was observed when the fins were combined with a textured surface.

[0062] [Regarding the point of decrease in heat transfer coefficient] In Examples 2, 3, and 7, and Comparative Examples 1-7, the point at which the heat transfer coefficient drops was higher compared to Comparative Example 8. That is, changing the boiling acceleration section from mesh to fins resulted in a rise in the point at which the heat transfer coefficient drops. Furthermore, in Examples 2, 3, and 7, an improvement in heat transfer coefficient was confirmed compared to Comparative Example 8. In Comparative Examples 1-7, there was a mix of conditions where the heat transfer coefficient improved compared to Comparative Example 8 and conditions where it did not. Also, the improvement rate of Examples 2, 3, and 7 compared to Comparative Example 8 was higher than the improvement rate of Comparative Examples 1-7 compared to Comparative Example 8. That is, at the point of heat transfer coefficient drop, simply changing the boiling acceleration section from mesh to fins did not improve the heat transfer coefficient much, but an improvement in heat transfer coefficient was observed by changing to fins and then creating a textured surface.

[0063] [Heat flux is 48W / cm 2 [Comparison at the time] In Comparative Example 8, burnout occurred, whereas in Examples 1-7 and Comparative Examples 1-7, burnout did not occur. The heat transfer coefficients of Examples 3, 4, and 7 were higher than those of all Comparative Examples 1-7.

[0064] [Comparison with and without a textured surface] In the CHF or heat flux range below the heat transfer coefficient reduction point, as shown in Tables 2 and 3, for all Examples 1 to 7 where the entire surface of the fin 7 is a matte surface, an improvement in the heat transfer coefficient was observed for each of Comparative Examples 1 to 7 of the same dimensions without the matte finish. Thus, by making the entire fin 7 a matte surface, an improvement in the heat transfer coefficient was confirmed in the CHF or heat flux range below the heat transfer coefficient reduction point. Also, at a heat flux of 48 W / cm 2 in the heat flux, for Examples 3 to 7 where the entire surface of the fin 7 is a matte surface, an improvement in the heat transfer coefficient was observed for each of Comparative Examples 3 to 7 of the same dimensions without the matte finish. That is, under the conditions where the thickness T is 0.1 mm or more and the gap G is 0.1 mm, an improvement in the heat transfer coefficient was also confirmed in a relatively high heat flux range.

[0065] [Comparison between fin and mesh] In Comparative Example 8 using a metal mesh, a sharp decrease in the heat transfer coefficient was observed when the heat flux reached 28 W / cm 2 . In contrast, in Examples 1 to 7 and Comparative Examples 1 to 7 using fins, the heat transfer coefficient reduction point was 30 W / cm 2 or more, and the reduction rate of the heat transfer coefficient was extremely low. In Comparative Example 8, burnout occurred when the heat flux was 28 W / cm 2 or more, while in Examples 1 to 7 and Comparative Examples 1 to 7, burnout did not occur in all measurement ranges.

[0066] [Regarding the gap of the fin] Between Example 3 and Example 7, only the size of the gap G is different. Below a heat flux of 45 W / cm 2 , the heat transfer coefficient of Example 3 with a smaller gap G is higher. Above that heat flux, the heat transfer coefficient reverses, and the heat transfer coefficient of Example 7 with a larger gap G becomes relatively higher. Similarly, between Comparative Example 3 and Comparative Example 7, only the size of the gap G is different, and the same tendency was observed.

[0067] [Regarding the thickness of the fin] The only difference between Example 6 and Example 7 is the thickness T. In the entire heat flux range, Example 7, with its smaller thickness T, showed a higher heat transfer coefficient.

[0068] [Regarding fin thickness and gap] In Examples 1-6, the ratio of thickness T to gap G is 1:1. The heat flux is 48 W / cm². 2 In the following examples, the heat transfer coefficient was highest in Example 3, where the thickness T and gap G were 0.1 mm. As the thickness T and gap G decreased, the heat transfer coefficient decreased, and as the thickness T and gap G increased, the heat transfer coefficient increased. Also, the heat flux was 48 W / cm². 2 When the value increased above this, the difference in heat transfer coefficients between Examples 3-6 decreased. That is, when the heat flux was 48 W / cm², the difference in heat transfer coefficients between Examples 3 and 6 decreased. 2 In the range greater than this, as the thickness T and gap G increased, the heat transfer coefficient tended to decrease less even when the heat flux increased. [Explanation of Symbols]

[0069] 1,4,6…Boiling acceleration section, 2…Base section, 3,5,6…Fins, 31…Inclined section, 32…Main body section, 2C…Fin arrangement area, 2D…Edge section, 51~53…Fin group, 10…Vapor chamber, 11…Vapor chamber body, 12…Connection section (soldering section, welding section)

Claims

1. The base part, It comprises a plurality of fins erected from the base portion, The fin has a main body portion extending perpendicularly to the base portion and an inclined portion at the connection point with the base portion that is inclined relative to the main body portion, and its entire surface is a pear-skin textured surface.

2. The boiling-promoting part according to claim 1, wherein the base portion is formed in the shape of a plate and has a thickness of 0.5 mm or more.

3. The boiling accelerating unit according to claim 1 or 2, wherein the base portion comprises a fin arrangement region on which the fins are provided and an edge portion formed around the fin arrangement region.

4. The boiling accelerating unit according to claim 1 or 2, wherein the surface roughness Ra of the pear-shaped surface of the fin is 0.5 μm or more.

5. The aforementioned fins are arranged in multiples in the direction of their plate thickness to form a fin group. The boiling accelerating unit according to claim 1 or 2, wherein a plurality of fin groups are arranged in a direction in which the fins extend along the base portion.

6. The boiling promotion unit according to claim 1 or 2, wherein the base portion and the plurality of fins are integrally formed.

7. The boiling accelerating unit according to claim 1 or 2, wherein the height of the plurality of fins decreases as they move toward one side in the direction extending along the base portion.

8. The boiling accelerating unit according to claim 1 or 2, wherein the height of the plurality of fins is 0.5 mm or more and 20 mm or less.

9. The boiling accelerating unit according to claim 1 or 2, wherein the thickness of the plurality of fins is 1 mm or less.

10. The device comprises a vapor chamber body thermally connected to a heat source, and a boiling accelerator as described in claim 1, A vapor chamber provided with a soldering joint connecting the vapor chamber body and the boiling accelerator.

11. The device comprises a vapor chamber body thermally connected to a heat source, and a boiling accelerator as described in claim 1, A vapor chamber having a welded joint connecting the vapor chamber body and the boiling acceleration unit.

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