Heat dissipation member, illumination device, and method for manufacturing heat dissipation member

Abstract

A heat dissipation member (1) has first protrusions (31) each having a first surface (41), and second protrusions (32) each having a second surface (42) facing the first surface (41). The material of the first surface (41) is different from the material of the second surface (42). The emission spectrum of the material of the first surface (41) and the emission spectrum of the material of the second surface (42) each have an average emissivity of 0.5 or more in a wavelength region of 2.5-25 μm. In at least 30% of the wavelength region of 2.5-25 μm, the difference between the emissivity in the emission spectrum of the material of the first surface (41) and the emissivity in the emission spectrum of the material of the second surface (42) is 0.3 or more.

Description

Heat dissipation member, lighting device, and method for manufacturing heat dissipation member

[0001] The present disclosure relates to a heat dissipation member, a lighting device, and a method for manufacturing a heat dissipation member.

[0002] A heat dissipation member such as a heat sink that includes heat dissipation fins with low emissivity surfaces and heat dissipation fins with high emissivity surfaces has been proposed (see, for example, Patent Document 1).

[0003] JP 2014-41929 A

[0004] Normally, a low-emissivity surface reduces the amount of heat dissipation, which reduces the heat dissipation performance of the heat dissipation component. Enlarging the low-emissivity surface to increase the amount of heat dissipation also increases the size of the heat dissipation component. Therefore, with conventional technology, it is difficult to achieve both high heat dissipation performance and compactness.

[0005] An object of the present disclosure is to solve the above-mentioned problems and to provide a heat dissipation member, a lighting device, or a method for manufacturing a heat dissipation member that achieves both high heat dissipation performance and miniaturization.

[0006] A heat dissipation member according to an aspect of the present disclosure comprises: a first protrusion having a first surface; and a second protrusion having a second surface facing the first surface, wherein the material of the first surface is different from the material of the second surface, the radiation spectrum of the material of the first surface and the radiation spectrum of the material of the second surface each have an average emissivity of 0.5 or more in a wavelength range of 2.5 μm to 25 μm, and a difference between the emissivity of the radiation spectrum of the material of the first surface and the emissivity of the radiation spectrum of the material of the second surface is 0.3 or more in a range of 30% or more in the wavelength range of 2.5 μm to 25 μm. A lighting device according to an aspect of the present disclosure comprises: a light-emitting element; and the heat dissipation member that dissipates heat from the light-emitting element. A method for manufacturing a heat dissipation member according to one aspect of the present disclosure is a method for manufacturing a heat dissipation member having a first protrusion having a first surface and a second protrusion having a second surface facing the first surface, comprising: providing the first protrusion and the second protrusion on a base plate so that the second surface faces the first surface; forming the first surface from a material different from that of the second surface such that the radiation spectrum of the material of the first surface has an average emissivity of 0.5 or more in a wavelength range of 2.5 μm or more and 25 μm or less; and forming the second surface from a material different from that of the first surface such that the radiation spectrum of the material of the second surface has an average emissivity of 0.5 or more in a wavelength range of 2.5 μm or more and 25 μm or less, wherein a difference between the emissivity of the radiation spectrum of the material of the first surface and the emissivity of the radiation spectrum of the material of the second surface is 0.3 or more in a range of 30% or more in the wavelength range of 2.5 μm or more and 25 μm or less.

[0007] According to the present disclosure, it is possible to provide a heat dissipation member, a lighting device, or a method for manufacturing a heat dissipation member that achieves both high heat dissipation performance and miniaturization.

[0008] FIG. 1 is a perspective view showing a heat dissipation member according to embodiment 1. FIG. 2 is a cross-sectional view of the heat dissipation member shown in FIG. 1. FIG. 3 is a cross-sectional view of the heat dissipation member shown in FIG. 3. FIG. 4 is a flowchart showing an example of a manufacturing method for the heat dissipation member according to embodiment 1. FIG. 5 is a table showing the heat dissipation performance of examples and comparative examples of embodiment 1. FIG. 6 is a perspective view showing a heat dissipation member according to embodiment 2. FIG. 7 is a cross-sectional view showing a heat dissipation member according to embodiment 3. FIG. 8 is a perspective view showing a heat dissipation member according to embodiment 4. FIG. 9 is a cross-sectional view showing a lighting device according to embodiment 5.

[0009] <First Embodiment> Fig. 1 is a perspective view showing a heat dissipation member 1 according to a first embodiment. Fig. 2 is a cross-sectional view of the heat dissipation member 1 shown in Fig. 1. The heat dissipation member 1 according to the first embodiment will be described below with reference to the drawings. The heat dissipation member 1 has a base plate 2 and a plurality of protrusions 3 provided on the surface of the base plate 2.

[0010] Each protrusion 3 has a surface layer 4 including a heat-releasing surface. In the example shown in FIG. 1 , a first protrusion 31 and a second protrusion 32 among the multiple protrusions 3 are adjacent to each other. The first protrusion 31 has a first surface layer 4a including a heat-releasing first surface 41. The second protrusion 32 has a second surface layer 4b including a heat-releasing second surface 42. The second surface layer 4b faces the first surface layer 4a. Therefore, the second surface 42 of the second protrusion 32 faces the first surface 41 of the first protrusion 31.

[0011] The base plate 2 transfers the heat generated in the heat source to the first protrusion 31 and the second protrusion 32. It is preferable that the base plate 2 be in direct contact with the first protrusion 31 and the second protrusion 32.

[0012] The base plate 2 may be selected appropriately from any material that can form the protrusions 3, and examples thereof include metals such as aluminum, iron, and copper, aluminum nitride, silicon nitride, boron nitride, zinc oxide, aluminum oxide, crystalline silica, titanium oxide, and manganese ferrite (FeMn). ２ O ３ ), ferric oxide (Fe ２ O ３), resin materials such as epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, silicone resin, and polyimide resin, or materials in which ceramic powder is mixed as a filler into a resin material, etc. can be used.

[0013] The shape of the base plate 2 may be appropriately selected from shapes that can be used as the heat dissipation member 1, such as a disk, a flat plate, or a plate shaped in any desired manner to suit the usage environment. Similarly, the cross-sectional shape of the base plate 2 may be appropriately selected from shapes that can be used as the heat dissipation member 1, such as a plate with a uniform thickness, a curved plate, or a plate with varying thickness in different locations. The thickness of the base plate 2 is preferably 10 mm or less so as not to impede heat conduction between the surface on which the protrusions 3 are provided and the surface opposite. The thickness of the base plate 2 does not include the height of the protrusions 3.

[0014] The shape and size of the protrusions 3 may be appropriately selected so as to form the first surface layer 4 a and the second surface layer 4 b. For example, the first surface layer 4 a and the second surface layer 4 b can be easily formed by making the cross section of the protrusions 3 mountain-shaped as shown in Figures 1 and 2 and setting the height of the protrusions in the range of 1 mm to 10 mm.

[0015] The protrusions 3 may be arranged so that the first surface layer 4a and the second surface layer 4b face each other. For example, as shown in Figures 1 and 2, the first surface layer 4a may be formed on one side of the protrusion 3 and the second surface layer 4b may be formed on the other side, and the first surface layer 4a and the second surface layer 4b may be formed in the same arrangement pattern on adjacent protrusions 3, so that the first surface layer 4a and the second surface layer 4b face each other.

[0016] FIG. 3 is a perspective view showing another example of the heat dissipation member 1. FIG. 4 is a cross-sectional view of the heat dissipation member 1 shown in FIG. 3. As shown in FIGS. 3 and 4, a first surface layer 4a may be formed on both side surfaces of a protrusion 3 (specifically, a first protrusion 31), and a second surface layer 4b may be formed on both side surfaces of an adjacent protrusion 3 (specifically, a second protrusion 32), with the first protrusions 31 and the second protrusions 32 arranged alternately. This allows the first surface layer 4a and the second surface layer 4b to be arranged facing each other. The arrangement shown in FIG. 1 and the arrangement shown in FIG. 3 may be combined.

[0017] The material of the first surface 41 is different from the material of the second surface 42. Thus, the material of the first surface layer 4a is different from the material of the second surface layer 4b.

[0018] The radiation spectrum of the material of the first surface 41 and the radiation spectrum of the material of the second surface 42 each preferably have an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm. Similarly, the radiation spectrum of the first surface layer 4a and the radiation spectrum of the second surface layer 4b each preferably have an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm.

[0019] The material of the first surface layer 4a may be appropriately selected from materials having an average emissivity of 0.5 or more in the wavelength region of 2.5 μm or more and 25 μm or less, such as aluminum nitride, silicon nitride, boron nitride, zinc oxide, aluminum oxide, crystalline silica, titanium oxide, manganese ferrite (FeMn), ２ O ３ ), ferric oxide (Fe ２ O ３ ), resin materials such as epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, silicone resin, and polyimide resin, or a material in which a ceramic powder is mixed into a resin material as a filler can be used.

[0020] Furthermore, if the base plate 2 and the protrusions 3 are made of a ceramic material, a resin material, or a resin material mixed with ceramic powder as a filler, the base material of the protrusions 3 may be exposed and used as the first surface layer 4a.

[0021] The protrusions 3 may have a surface layer 4 and a support member that supports the surface layer 4. In this case, the support member is, for example, a metal member. When the base plate 2 and the protrusions 3 are made of metal, the first surface layer 4a may be formed by oxidizing the surface of the protrusions 3 using, for example, anodization, and then covering the metal surface with the generated metal oxide.

[0022] The material of the second surface layer 4b can be selected from the same materials as the material of the first surface layer 4a, and for example, a ceramic material, a resin material, or a resin material mixed with ceramic material powder as a filler can be used.

[0023] Furthermore, if the base plate 2 and the protrusions 3 are made of a ceramic material, a resin material, or a resin material mixed with ceramic powder as a filler, and the same material is not selected for the first surface layer 4a, the base material of the protrusions 3 may be exposed and used as the first surface layer 4a.

[0024] Furthermore, when the base plate 2 and the protrusions 3 are made of metal and the oxide thereof is not selected as the first surface layer 4a, the first surface layer 4a may be formed by oxidizing the surface of the protrusions 3 using, for example, anodization, and then covering the surface of the metal with the resulting metal oxide.

[0025] Emissivity refers to the ratio of the infrared radiation intensity of a substance to the infrared radiation intensity of a blackbody, and is measured using a Fourier transform infrared spectrophotometer. Average emissivity is the average of the emissivities in the wavelength range of 2.5 μm to 25 μm. The radiation spectrum represents the emissivity for each wavelength. The difference in emissivity represents the difference in emissivity between the first surface layer 4a and the second surface layer 4b at the same wavelength. It is preferable that the difference in emissivity between the radiation spectrum of the material of the first surface 41 and the radiation spectrum of the material of the second surface 42 be 0.3 or more in a range of 30% or more in the wavelength range of 2.5 μm to 25 μm.

[0026] The higher the emissivity, the better the heat dissipation performance. Therefore, if the average emissivity of at least one of the first surface layer 4a or the second surface layer 4b is 0.6 or higher, the heat dissipation performance can be improved further, and if it is 0.7 or higher, the heat dissipation performance can be improved even further.

[0027] Generally, a portion of the infrared radiation that strikes a material is absorbed and becomes heat. The absorption rate corresponds to the radiation spectrum of the material. Therefore, infrared radiation of wavelengths with a small difference in emissivity is absorbed by the opposing surfaces of the protrusions, degrading the heat dissipation performance of the heat dissipation component. For example, if the difference in emissivity is less than 0.3, the proportion of infrared radiation absorbed by the other protrusions increases, degrading the heat dissipation performance. Furthermore, if the area that can prevent mutual absorption of radiation is less than 30%, the proportion of infrared radiation absorbed by the other protrusions increases across the entire heat dissipation component, degrading the heat dissipation performance.

[0028] The greater the difference in emissivity and the wider the area of ​​the difference, the more the heat dissipation performance can be improved by preventing mutual absorption of radiation, so it is more preferable that the difference in emissivity is 50% or more. Furthermore, it is more preferable that the difference in emissivity is 0.4 or more, and even more preferable that it is 0.5 or more.

[0029] If the surface roughness Ra of the first surface layer 4a and the second surface layer 4b is less than 0.1 μm by mirror polishing or other methods, the emissivity and heat dissipation performance will decrease. Therefore, it is preferable that the surface roughness Ra of at least one of the first surface layer 4a or the second surface layer 4b be 0.1 μm or more. That is, it is preferable that the surface roughness Ra of at least one of the first surface 41 or the second surface 42 be 0.1 μm or more. It is more preferable that the surface roughness Ra of both the first surface layer 4a and the second surface layer 4b be 0.1 μm or more. That is, it is more preferable that the surface roughness Ra of both the first surface 41 and the second surface 42 be 0.1 μm or more.

[0030] When the first surface layer 4 a and the second surface layer 4 b are formed by surface coating, if the thickness is less than 10 μm, the emissivity and heat dissipation performance will decrease. Therefore, it is preferable that at least one of the first surface layer 4 a and the second surface layer 4 b has a film thickness of 10 μm or more.

[0031] The surface coating refers to forming the first surface layer 4a or the second surface layer 4b with a ceramic material, a resin material, a material in which a resin material is mixed with ceramic powder as a filler, or a metal oxide obtained by oxidizing the surface of the protrusion 3 using anodization or the like.

[0032] The base plate 2 and the protrusions 3 each preferably have a thermal conductivity of 20 W / mK or higher so as not to impede heat conduction, since they serve as a path for transmitting heat generated in the heat source to the first surface layer 4 a and the second surface layer 4 b. It is more preferable that the base plate 2 and the protrusions 3 each be made of a material with a thermal conductivity of 30 W / mK or higher.

[0033] 5 is a flowchart showing an example of a method for manufacturing the heat dissipation member 1 according to the first embodiment. The method for manufacturing the heat dissipation member 1 according to the present embodiment will be described with reference to the flowchart in FIG. 5. In step S1, a base plate 2 is prepared. The preparation method is selected according to the material. For example, a ceramic material, a resin material, or a material obtained by mixing a ceramic powder as a filler into a resin material is prepared, and the material is formed into a desired shape by a method such as cutting or machining.

[0034] In step S2, protrusions 3 are provided on the surface of the base plate 2. For example, the first protrusions 31 and the second protrusions 32 are provided on the surface of the base plate 2 so that the second surface 42 faces the first surface 41. Methods for providing the protrusions 3 include, for example, cutting the material that constitutes the base plate 2, or adhering the protrusions 3 to the base plate 2 after forming them into a desired shape by cutting or machining them in the same way as the base plate 2.

[0035] In step S3, a combination of the material of the first surface layer 4a including the first surface 41 and the material of the second surface layer 4b including the second surface 42 is determined. In this case, a material different from the material of the second surface layer 4b is selected as the material of the first surface layer 4a. Furthermore, the material of the first surface layer 4a including the first surface 41 is determined so that the radiation spectrum of the material of the first surface 41 has an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm. Similarly, the material of the second surface layer 4b including the second surface 42 is determined so that the radiation spectrum of the material of the second surface 42 has an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm.

[0036] In step S4, the first surface 41 is formed using a material different from the material of the second surface 42 so that the radiation spectrum of the material of the first surface 41 has an average emissivity of 0.5 or more in the wavelength region of 2.5 μm or more and 25 μm or less. For example, first, the first surface layer 4 a is formed on the first protrusion 31. Methods for forming the first surface layer 4 a include sintering a ceramic material on the surface, or applying a resin material or a resin material mixed with a filler using a spraying method, a dipping method, a brush coating method, a screen printing method, a transfer method, or the like.

[0037] When the first surface layer 4a is formed from the same material as the base plate 2 and the protrusions 3, the protrusions 3 may not be surface-coated, and the base material may be exposed to form the first surface layer 4a. When the base plate 2 and the protrusions 3 are made of metal, the first surface layer 4a may be formed by oxidizing the surface using anodizing or the like. When forming the first surface layer 4a, it is preferable not to form the first surface layer 4a on the surface on which the second surface layer 4b will later be formed, so as not to interfere with the formation of the second surface layer 4b. Examples of methods for this include covering the surface of the first surface layer 4a with masking tape or the like before forming the first surface layer 4a and then removing the masking tape, or forming the first surface layer 4a and then removing the portion covering the surface on which the second surface layer 4b will later be formed using sandblasting or the like.

[0038] In step S5, the second surface 42 is formed from a material different from that of the first surface 41 so that the radiation spectrum of the material of the second surface 42 has an average emissivity of 0.5 or greater in the wavelength region of 2.5 μm to 25 μm. For example, the second surface layer 4b is first formed on the surface facing the first surface layer 4a so as not to cover the first surface layer 4a. Any method may be used to form the second surface layer 4b on top of the first surface layer 4a without covering it. Examples of such a method include covering the surface of the first surface layer 4a with masking tape or the like, then forming the second surface layer 4b, and then peeling off the masking tape, or forming the second surface layer 4b and then removing the portion covering the first surface layer 4a by sandblasting or the like.

[0039] The method for forming the second surface layer 4b can be the same as the method for forming the first surface layer 4a, and examples thereof include sintering a ceramic material on the surface, or applying a resin material or a resin material mixed with a filler using a spraying method, a dipping method, a brush coating method, a screen printing method, a transfer method, or the like. Furthermore, when the second surface layer 4b is formed using the same material as the base plate 2 and the protrusions 3, the protrusions 3 may not be surface-coated, and the base material may be exposed to form the second surface layer 4b. When the base plate 2 and the protrusions 3 are made of metal, the surface may be oxidized using anodizing or the like to form the second surface layer 4b.

[0040] In steps S4 and S5, the first surface 41 and the second surface 42 are formed so that the difference in emissivity of the radiation spectrum between the material of the first surface 41 and the material of the second surface 42 is 0.3 or more in a range of 30% or more in the wavelength range of 2.5 μm or more and 25 μm or less.

[0041] <Examples> The advantages of the heat dissipation member 1 according to the present disclosure will be described with reference to Fig. 6. Fig. 6 is a table showing the heat dissipation performance of examples of embodiment 1 and comparative examples. Embodiment 1 is applied to examples 1 to 4, and embodiment 1 is not applied to comparative examples 1 and 2.

[0042] [Example 1] Example 1 is a sample in which the surface of an alumina base plate is cut to form protrusions with mountain-shaped cross sections, and the side surfaces of all the protrusions facing in the same direction are left as the first surface layer 4a, while the other side surfaces are coated with silicone resin.

[0043] [Example 2] Example 2 is a sample obtained in the same manner as Example 1, except that after applying the silicone resin, the surface to which the silicone resin was applied was roughened with a file to a surface roughness Ra of 0.1 μm.

[0044] Example 3 Example 3 is a sample obtained in the same manner as Example 1, except that the silicone resin was applied thickly to a film thickness of 10 μm.

[0045] Example 4 Example 4 is a sample obtained in the same manner as Example 1, except that high-purity alumina with a thermal conductivity of 20 W / mK was used as the material for the base plate.

[0046] Comparative Example 1 Comparative Example 1 is a sample obtained in the same manner as in Example 1, except that aluminum tape having an average emissivity of 0.1 was attached instead of the silicone resin.

[0047] Comparative Example 2 is a sample obtained in the same manner as in Example 1, except that a paint containing a mixture of alumina powder and silicone resin was applied instead of silicone resin. The region in which the difference in emissivity between the paint mixed with silicone resin is 0.3 or more is 20%.

[0048] The heat dissipation performance of the samples of Examples 1 to 4 and Comparative Examples 1 and 2 described above was evaluated as follows. In this evaluation method, the size of the heat dissipation member 1 was 50 mm x 50 mm, and the protrusions 3 were formed to a height of 5 mm. A ceramic heater was attached to the surface of the heat dissipation member 1 opposite the surface on which the protrusions 3 were provided. Power was applied to the ceramic heater of each sample, and the sample was left for several hours until the temperature of the sample and the ceramic heater reached a saturation temperature. The surface temperature of the ceramic heater was then measured using a thermocouple or the like.

[0049] The evaluation results for heat dissipation performance were based on the saturation temperature obtained for the sample of Example 1. If the saturation temperature obtained for each sample of Examples 2 to 4 and Comparative Examples 1 and 2 was lower than the saturation temperature of Example 1, it was rated as "excellent," if it was the same, it was rated as "good," and if it was higher, it was rated as "poor."

[0050] In the sample of Example 2, the surface roughness Ra of the silicone resin surface was set to 0.1 μm, which improved the heat dissipation performance and lowered the saturation temperature. In the sample of Example 3, the film thickness of the silicone resin was set to 10 μm, which improved the heat dissipation performance and lowered the saturation temperature. In the sample of Example 4, the thermal conductivity of the base plate was set to 20 W / mK, which improved the heat dissipation performance and lowered the saturation temperature.

[0051] In the sample of Comparative Example 1, the heat dissipation performance deteriorated and the saturation temperature increased because aluminum tape was used to set the average emissivity of either the first surface 41 or the second surface 42 to less than 0.5. In the sample of Comparative Example 2, paint containing a mixture of alumina powder and silicone resin was used, and when the area where the difference in emissivity between the first surface 41 and the second surface 42 was 0.3 or greater was less than 30%, the heat dissipation performance deteriorated and the saturation temperature increased.

[0052] According to the first embodiment, it is possible to provide a heat dissipation member 1 or a method for manufacturing a heat dissipation member 1 that achieves both high heat dissipation performance and miniaturization.

[0053] 7 is a perspective view showing a heat dissipation member 101 according to embodiment 2. The heat dissipation member 101 according to embodiment 2 will be described below with reference to the drawing. Note that components having the same functions as those described in embodiment 1 above are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0054] The heat dissipation member 101 has a base plate 2 and a plurality of protrusions 103 provided on the surface of the base plate 2. The plurality of protrusions 103 include first protrusions 31 and second protrusions 32. In the example shown in FIG. 7 , each protrusion 103 is a pyramidal protrusion. As described in the first embodiment, the first protrusion 31 has a first surface layer 4a including a first surface 41, and the second protrusion 32 has a second surface layer 4b including a second surface 42. The shape and size of each protrusion 103 may be appropriately selected so as to form the first surface layer 4a and the second surface layer 4b.

[0055] The protrusions 103 may be arranged so that the first surface layer 4 a and the second surface layer 4 b face each other. For example, as shown in Fig. 7, the protrusions 103 are arranged so that the side surface of one protrusion 103 (e.g., the first protrusion 31) is the first surface layer 4 a and the side surface of the adjacent protrusion 103 (e.g., the second protrusion 32) is the second surface layer 4 b.

[0056] According to the second embodiment, by using a combination of high-emissivity materials for both first surface 41 and second surface 42 but with different radiation spectra, it is possible to improve the heat dissipation performance from each surface while preventing the opposing surfaces from absorbing each other's radiation, thereby improving the heat dissipation performance of the entire heat dissipation member 101. Therefore, it is possible to reduce the volume required to achieve the heat dissipation performance required of heat dissipation member 101, and to provide a heat dissipation member 101 that combines high heat dissipation performance with compact size.

[0057] 8 is a cross-sectional view showing a heat dissipation member 201 according to embodiment 3. The heat dissipation member 201 according to embodiment 3 will be described below with reference to the drawings. Note that components having the same functions as those described in embodiment 1 above are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0058] The heat dissipation member 201 has a base plate 2 and a plurality of protrusions 203 provided on the surface of the base plate 2. The plurality of protrusions 203 include a first protrusion 31 and a second protrusion 32. In the example shown in FIG. 8 , each protrusion 203 is a plate-shaped protrusion. As described in the first embodiment, the first protrusion 31 has a first surface layer 4a including a first surface 41, and the second protrusion 32 has a second surface layer 4b including a second surface 42. The shape and size of each protrusion 203 may be appropriately selected so as to form the first surface layer 4a and the second surface layer 4b.

[0059] The protrusions 203 may be arranged so that the first surface layer 4 a and the second surface layer 4 b face each other. For example, as shown in Fig. 8, the protrusions 203 are arranged so that the side surface of one protrusion 203 (e.g., the first protrusion 31) is the first surface layer 4 a and the side surface of the adjacent protrusion 203 (e.g., the second protrusion 32) is the second surface layer 4 b.

[0060] According to the third embodiment, by using materials with high emissivity for both first surface 41 and second surface 42 but with different radiation spectra, it is possible to improve the heat dissipation performance from each surface while preventing the opposing surfaces from absorbing each other's radiation, thereby improving the heat dissipation performance of the entire heat dissipation member 201. Therefore, it is possible to reduce the volume required to achieve the heat dissipation performance required of heat dissipation member 201, and to provide heat dissipation member 201 that combines high heat dissipation performance with compact size.

[0061] 9 is a perspective view showing a heat dissipation member 301 according to embodiment 4. The heat dissipation member 301 according to embodiment 4 will be described below with reference to the drawings. Note that components having the same functions as those described in embodiment 1 above are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0062] The heat dissipation member 301 has a base plate 2 and a plurality of protrusions 303 provided on the surface of the base plate 2. The plurality of protrusions 303 include first protrusions 31 and second protrusions 32. In the example shown in FIG. 9 , each protrusion 303 is a cubic protrusion. As described in the first embodiment, the first protrusion 31 has a first surface layer 4a including a first face 41, and the second protrusion 32 has a second surface layer 4b including a second face 42. The shape and size of each protrusion 303 may be appropriately selected so as to form the first surface layer 4a and the second surface layer 4b.

[0063] The protrusions 303 may be arranged so that the first surface layer 4 a and the second surface layer 4 b face each other. For example, as shown in Fig. 9, the protrusions 303 are arranged so that the side surface of one protrusion 303 (e.g., the first protrusion 31) is the first surface layer 4 a and the side surface of the adjacent protrusion 303 (e.g., the second protrusion 32) is the second surface layer 4 b.

[0064] According to the fourth embodiment, by using a combination of high-emissivity materials for both first surface 41 and second surface 42 but with different radiation spectra, it is possible to improve the heat dissipation performance from each surface while preventing the opposing surfaces from absorbing each other's radiation, thereby improving the heat dissipation performance of the entire heat dissipation member 301. Therefore, it is possible to reduce the volume required to achieve the heat dissipation performance required of heat dissipation member 301, and to provide a heat dissipation member 301 that combines high heat dissipation performance with a compact size.

[0065] <Fifth Embodiment> Fig. 10 is a cross-sectional view showing a lighting device 5 according to a fifth embodiment. The lighting device 5 according to the fifth embodiment will be described below with reference to the drawings. The lighting device 5 according to the fifth embodiment has a heat dissipation member 51 and a light-emitting element 52 as a heat source. The heat dissipation member 51 is any one of the heat dissipation members 1, 101, 201, or 301 described in the first to fourth embodiments. The light-emitting element 52 is, for example, a light-emitting diode (LED). In this case, the lighting device 5 is an LED lighting device. The heat dissipation member 51 dissipates heat from the light-emitting element 52.

[0066] The heat dissipation member 51 and the light emitting element 52 may be connected in any manner so as to efficiently dissipate heat from the light emitting element 52. For example, the light emitting element 52 may be directly bonded to the heat dissipation member 51, screwed, or connected via a mounting jig made of a material with high thermal conductivity such as ceramic or metal.

[0067] The base plate 2 described in the first embodiment may be disposed between the heat dissipation member 51 and the light emitting element 52 .

[0068] According to the lighting device 5 of embodiment 5, since it has any of the heat dissipation members 1, 101, 201, or 301 described in embodiments 1 to 4, it is possible to provide a lighting device 5 that combines high heat dissipation performance with compact size.

[0069] The features of the above-described embodiments can be combined with each other.

[0070] REFERENCE SIGNS LIST 1, 51, 101, 201, 301 Heat dissipation member, 2 Base plate, 3, 103, 203, 303 Protrusion, 4 Surface layer, 4a First surface layer, 4b Second surface layer, 5 Lighting device, 31 First protrusion, 32 Second protrusion, 41 First surface, 42 Second surface, 52 Light-emitting element.

Claims

1. A heat dissipation component comprising: a first protrusion having a first surface; and a second protrusion having a second surface facing the first surface; the material of the first surface is different from the material of the second surface; the radiation spectrum of the material of the first surface and the radiation spectrum of the material of the second surface each have an average emissivity of 0.5 or greater in a wavelength range of 2.5 μm to 25 μm; and the difference in emissivity between the radiation spectrum of the material of the first surface and the radiation spectrum of the material of the second surface is 0.3 or greater in a range of 30% or greater in the wavelength range of 2.5 μm to 25 μm.

2. The heat dissipation member according to claim 1, wherein the surface roughness Ra of at least one of the first surface and the second surface is 0.1 μm or more.

3. The heat dissipation member according to claim 1, characterized in that the first protrusion has a first surface layer including the first surface, the second protrusion has a second surface layer including the second surface, and at least one of the first surface layer and the second surface layer has a film thickness of 10 μm or more.

4. A heat dissipation member according to any one of claims 1 to 3, further comprising a base plate that transfers heat to the first protrusions and the second protrusions, wherein the thermal conductivity of the base plate is 20 W / mK or more.

5. A lighting device comprising: a light-emitting element; and a heat dissipation member according to any one of claims 1 to 4 that dissipates heat from the light-emitting element.

6. A method for manufacturing a heat dissipation member having a first protrusion having a first surface and a second protrusion having a second surface facing the first surface, comprising: providing the first protrusion and the second protrusion on a base plate so that the second surface faces the first surface; forming the first surface from a material different from that of the second surface so that the radiation spectrum of the material of the first surface has an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm; and forming the second surface from a material different from that of the first surface so that the radiation spectrum of the material of the second surface has an average emissivity of 0.5 or more in the wavelength range of 2.5 μm to 25 μm, wherein the difference in emissivity between the radiation spectrum of the material of the first surface and the radiation spectrum of the material of the second surface is 0.3 or more in a range of 30% or more in the wavelength range of 2.5 μm to 25 μm.

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