Heat dissipation member and electronic device

Abstract

This heat dissipation member comprises: a base material having a first surface extending along an X direction and a Y direction intersecting each other, a second surface facing the first surface, and a side surface located between the first surface and the second surface and extending along a Z direction intersecting the X direction and the Y direction; a first plate material having a cooling fin and fixed to the first surface; and a second plate material fixed to the second surface. The base material has a structure in which graphite blocks are laminated in at least three layers in the Z direction. Of the graphite blocks adjacent to each other, one graphite block has a structure in which a plurality of layers of graphene are laminated in the X-direction, and the other graphite block has a structure in which a plurality of layers of graphene are laminated in the Y-direction.

Description

Heat dissipation member and electronic device

[0001] The present disclosure relates to a heat dissipation member and an electronic device.

[0002] Patent Document 1 describes an aluminum base plate that is provided with a plurality of aluminum pin fins as a heat dissipation member.

[0003] Patent No. 7241923

[0004] A heat dissipation member according to the present disclosure comprises: a base having a first surface extending along an X direction and a Y direction intersecting each other, a second surface opposite the first surface, and a side surface located between the first surface and the second surface and extending along a Z direction intersecting the X direction and the Y direction; a first plate material having cooling fins and fixed to the first surface; and a second plate material fixed to the second surface, wherein the base has a structure in which at least three layers of graphite blocks are stacked in the Z direction, and of the graphite blocks adjacent to each other, one graphite block has a structure in which a plurality of graphenes are stacked in the X direction, and the other graphite block has a structure in which a plurality of graphenes are stacked in the Y direction.

[0005] An electronic device according to the present disclosure includes the heat dissipation member described above and an electronic element connected to the second plate member.

[0006] 1A ; FIG. 1B is a perspective view of a heat dissipation member according to a first embodiment of the present disclosure; FIG. 1C is a perspective view of a heat dissipation member according to a first embodiment of the present disclosure, with a protective layer removed; FIG. 1D is a perspective view of a heat dissipation member according to a first embodiment of the present disclosure, with a substrate; FIG. 1E is a cross-sectional view taken along line A-A of FIG. 1A; FIG. 1F is a view illustrating properties of a graphite block; FIG. 1G is a cross-sectional view showing a third surface of the graphite block; FIG. 1H is a cross-sectional view showing a fourth surface of the graphite block; FIG. 1I is an exploded perspective view of a substrate; FIG. 1J is a perspective view of a first plate and cooling fins; FIG. 1J is a perspective view showing modified examples of the first plate and cooling fins; FIG. 1I is a view showing a first use example of a heat dissipation member; FIG. 1J is a view showing a second use example of a heat dissipation member; FIG. 1I is a perspective view of a heat dissipation member according to a second embodiment of the present disclosure; FIG. 1J is a perspective view of a heat dissipation member according to a second embodiment of the present disclosure, with a protective layer removed; FIG. 1J is a perspective view of a heat dissipation member according to a second embodiment of the present disclosure, with a substrate; FIG. 1I is an exploded perspective view of a substrate; FIG. 1J is a cross-sectional view of a heat dissipation member; FIG. 1I is a view illustrating a method for manufacturing a heat dissipation member according to the present disclosure; FIG. 1J is a view illustrating a method for manufacturing a heat dissipation member according to the present disclosure; 1A to 1C are diagrams illustrating a method for manufacturing a heat dissipation member according to the present disclosure.

[0007] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. Further improvement in heat dissipation performance is required for heat dissipation components. However, with metal heat dissipation components, the heat dissipation performance is determined by the thermal conductivity of the metal used, making it difficult to further improve the heat dissipation performance. An object of the present disclosure is to provide a heat dissipation component and an electronic device with improved heat dissipation performance.

[0008] 1A, 1B, and 1C are diagrams showing an example of a heat dissipation member 100 according to a first embodiment of the present disclosure, where Fig. 1A is a perspective view of the heat dissipation member 100, Fig. 1B is a perspective view of the configuration excluding the protective layer 150, and Fig. 1C is a perspective view of the substrate 110 (a perspective view of the configuration excluding the protective layer 150, the first plate member 120, the cooling fins 126, and the second plate member 130). Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1A. Fig. 3 is a diagram illustrating the properties of a graphite block 10.

[0009] The heat dissipation member 100 of one embodiment has high thermal conductivity and can quickly transfer heat received at the lower surface 102 to the upper surface 101. The heat dissipation member 100 may be a heat sink. The lower surface 102 of the heat dissipation member 100 may be thermally connected to a heat source (electronic element 350, 450, etc.).

[0010] The heat dissipation member 100 may include a base material 110. The base material 110 may have a first surface 111 extending along an X direction and a Y direction that intersect (e.g., are perpendicular to) each other, a second surface 112 located opposite the first surface 111, and a side surface 113 located between the first surface 111 and the second surface 112 and extending along a Z direction that intersects (e.g., is perpendicular to) the X direction and the Y direction. The heat dissipation member 100 may further include second bonding materials 140 located on the first surface 111 and the second surface 112, a first plate material 120 fixed to the first surface 111 via the second bonding material 140, a second plate material 130 fixed to the second surface 112 via the second bonding material 140, and a protective layer 150 covering the side surface 113.

[0011] <<Substrate>> The substrate 110 may have a structure in which a plurality of graphite blocks 10 are stacked in the Z direction. The graphite blocks 10 may have a structure in which a plurality of graphenes are stacked in the first direction A1. Graphene may be a sheet-like substance in which a honeycomb structure formed by bonding carbon atoms extends in a two-dimensional direction. Adjacent graphenes may be bonded to each other by intermolecular forces, which are van der Waals forces.

[0012] The surface of graphite block 10 may have a surface where graphene spreads in a two-dimensional direction and a surface where multiple graphene layers appear. Hereinafter, the surface where graphene spreads in a two-dimensional direction will be referred to as a "crystal surface," and the surface where graphene layers appear will be referred to as a "crystal layer surface." In the drawings, the "crystal surface" will be represented by a honeycomb pattern, and the "crystal layer surface" will be represented by a striped pattern.

[0013] Graphite block 10 may have anisotropy in its brittleness. For example, as anisotropy in its brittleness, graphite block 10 may have a tendency to easily cleave along a plane in which graphene extends, i.e., a plane intersecting first direction A1, as shown in FIG. 3 . Cleavage means breaking along a certain plane. FIG. 3 shows a state in which crack E1 has occurred due to cleavage.

[0014] Furthermore, as anisotropy of the brittleness, graphite block 10 may have a property in which, when stress is applied along the crystal plane, graphene located on the crystal plane is easily peeled off. Furthermore, graphite block 10 may have a property in which edge portions E2 (see FIGS. 4 and 5 ) of the graphene are weak and easily broken from edge portions E2.

[0015] The graphite block 10 may be made of a material whose main component is pyrolytic graphite. The term "main component" may mean a volume ratio of 80% or more. The pyrolytic graphite may be manufactured, for example, by depositing and laminating hydrocarbons, followed by pressure annealing.

[0016] <Each Surface of Graphite Block> Figure 4 is a cross-sectional view showing third surface 13 of graphite block 10. Figure 5 is a cross-sectional view showing fourth surface 14 of graphite block 10. Figure 4 shows part C1 of Figure 3, and Figure 5 shows part C2 of Figure 3. Graphite block 10 may be a rectangular parallelepiped, with two opposite surfaces being crystal planes and the remaining four surfaces being crystal layer planes.

[0017] The surfaces of graphite block 10 may include a first surface 11 extending along a first direction A1 and a second direction A2 that intersect (e.g., are perpendicular to) each other, a second surface 12 located opposite first surface 11, and a third surface 13 and a fourth surface 14 located between first surface 11 and second surface 12 and extending along a third direction A3 that intersects (e.g., is perpendicular to) first direction A1 and second direction A2. In graphite block 10, two third surfaces 13 located opposite each other may be crystal planes, and first surface 11, second surface 12, and two fourth surfaces 14 located opposite each other may be crystal layer planes. In other words, a side surface of graphite block 10 may include third surface 13 which is a crystal plane and fourth surface 14 which is a crystal layer plane.

[0018] The third surface 13, which is a crystal plane, may be a plane extending in two directions intersecting the first direction A1. The two directions may be a second direction A2 and a third direction A3 that are perpendicular to the first direction A1 and perpendicular to each other. The fourth surface 14, which is a crystal layer plane, may be a plane extending in the first direction A1 and the third direction A3. As shown in FIG. 4, the third surface 13 is a crystal plane where graphene peeling is likely to occur, and edge portions E2 of graphene that are prone to breakage may appear. As shown in FIG. 5, the fourth surface 14 has edge portions E2 of graphene that are prone to breakage. As shown in FIG. 2, a configuration in which the side surface 113 is covered with the protective layer 150 can reduce the occurrence of peeling or breakage and improve the toughness of the heat dissipation member 100.

[0019] The multiple graphite blocks 10 may be stacked in the Z direction with the third direction A3 parallel to the Z direction (i.e., the direction from the second plate member 130 to the first plate member 120). That is, adjacent graphite blocks 10 may be joined at the first surface 11 and the second surface 12, which are surfaces intersecting the third direction A3. The first surface 11 and the second surface 12 may be the crystal layer surface with the largest area among the four crystal layer surfaces and the crystal layer surface opposite to that surface. This configuration can improve the stability of the joining between the graphite blocks 10.

[0020] <Thermal Conductivity of Graphite Block> The graphite block 10 may have very high thermal conductivity in directions along the crystal planes. The thermal conductivity of the graphite block 10 in the second direction A2 and the third direction A3 may be 200 W / m·K or more, while the thermal conductivity in the first direction A1 may be lower than the thermal conductivity in the second direction A2 or the third direction A3, such as 7 W / m·K. That is, the graphite block 10 may have anisotropic thermal conduction. The thermal conductivity in the second direction A2 and the third direction A3 may be preferably 370 W / m·K or more, more preferably 450 W / m·K or more, and even more preferably 800 W / m·K or more. In one embodiment, the thermal conductivity of the graphite block 10 in the second direction A2 and the third direction A3 may be 1200 W / m·K or more, more specifically, approximately 1700 W / m·K.

[0021] <Surface Roughness of Graphite Block> As shown in FIG. 4 , in graphite block 10, the surface roughness of third surface 13, which is a crystal plane, may be smaller than the surface roughness of first surface 11, which is a crystal layer plane. Specifically, the surface roughness of first surface 11 may be 20 times or more, 10 times or more but less than 20 times, or 5 times or more but less than 10 times the surface roughness of third surface 13. The surface roughness refers to the arithmetic mean roughness Ra defined in JIS (Japanese Industrial Standards) B_0601:2001. With this configuration, as shown in FIG. 4 , the number of graphene edge portions E2 appearing on third surface 13 is reduced. Therefore, the brittleness of third surface 13 can be reduced.

[0022] As shown in Figures 4 and 5, in graphite block 10, the surface roughness of fourth surface 14, which is a crystal layer surface, may be greater than the surface roughness of third surface 13, which is a crystal surface. Specifically, the surface roughness of fourth surface 14 may be 20 times or more, 10 times or more but less than 20 times, or 5 times or more but less than 10 times the surface roughness of third surface 13. The surface roughness refers to the arithmetic mean roughness Ra described above. As shown in Figure 5, fourth surface 14 includes relatively large irregularities due to the above surface roughness. The irregularities may be fine irregularities.

[0023] <Thermal Expansion Characteristics of Graphite Block> The linear expansion coefficient of graphite block 10 may be highly anisotropic at first surface 11, second surface 12, and third surface 14. That is, graphite block 10 may have a very low linear expansion coefficient in a direction along a crystal plane. Specifically, the linear expansion coefficient of graphite block 10 may be 20 [10^-6 / K] or more in first direction A1 and 0.050 [10^-6 / K] or less in second direction A2 and third direction A3. Furthermore, the linear expansion coefficient of graphite block 10 may be 24 [10^-6 / K] or more in first direction A1. Furthermore, the linear expansion coefficient of graphite block 10 may be a value in the range of 27 [10^-6 / K] or less in first direction A1. The linear expansion coefficient of the graphite block 10 in the second direction A2 and the third direction A3 may be a negative value, specifically, may be −0.001 [10−6 / K] or less. The linear expansion coefficient of the graphite block 10 in the second direction A2 and the third direction A3 may be −1.0 [10−6 / K] or more.

[0024] <Stacking of Graphite Blocks> FIG. 6 is an exploded perspective view of the substrate 110. As shown in FIGS. 1, 2, and 6, multiple graphite blocks 10 may be arranged in parallel in the Z direction (i.e., the direction from the second plate member 130 to the first plate member 120). This configuration increases the design flexibility of the heat dissipation member 100, for example, by allowing the dimensions of the heat dissipation member 100 to be increased in the Z direction (the height direction of the heat dissipation member 100). When arranged in parallel in the Z direction, the multiple graphite blocks 10 may be arranged in one direction along a crystal plane, i.e., one of the second direction A2 and the third direction A3 (e.g., the third direction A3) having high thermal conductivity, parallel to the Z direction. This configuration enables rapid heat conduction from the second plate member 130 to the first plate member 120.

[0025] The multiple graphite blocks 10 may include at least a first graphite block 10a, a second graphite block 10b adjacent to the first graphite block 10a, and a third graphite block 10c adjacent to the second graphite block 10b and located on the opposite side of the first graphite block 10a.

[0026] The first direction A1 in which graphene is stacked does not have to coincide among the multiple graphite blocks 10. That is, the first direction A1a in the first graphite block 10a and the first direction A1b in the second graphite block 10b may intersect with each other. Furthermore, the first direction A1c in the third graphite block 10c and the first direction A1b in the second graphite block 10b may intersect with each other. Specifically, for example, as shown in FIG. 6 , the first graphite block 10a may be arranged such that the first direction A1a in which graphene is stacked is parallel to the Y direction. The second graphite block 10b may be arranged such that the first direction A1b in which graphene is stacked is parallel to the X direction. The third graphite block 10c may be arranged such that the first direction A1c in which graphene is stacked is parallel to the Y direction.

[0027] According to this configuration, when heat is conducted from a portion of the second plate 130 to the first plate 120, the heat spreads in the second direction A2a in the graphite block 10 closest to the second plate 130 and is then conducted to the next graphite block 10. Then, in the next graphite block 10, the heat spreads in the second direction A2b and is then conducted to the next graphite block 10. As a result, the heat is dispersed in the second directions A2a and A2b that intersect with each other. Therefore, the anisotropy of the thermal conduction of the base material 110 is reduced, and heat can be conducted through a larger area of ​​the base material 110. Therefore, efficient heat transfer performance can be achieved.

[0028] Furthermore, with this configuration, the orientations of the crystal planes do not coincide among the multiple graphite blocks 10. That is, with this configuration, the second direction A2a in the first graphite block 10a and the second direction A2b in the second graphite block 10b intersect with each other. Also, the second direction A2c in the third graphite block 10c and the second direction A2b in the second graphite block 10b intersect with each other. Therefore, the anisotropy of the linear expansion coefficient of the base material 110 is reduced. That is, with this configuration, the linear expansion coefficients of the upper surface 101 and the lower surface 102 of the heat dissipation member 100 can be made closer to isotropic values ​​compared to a configuration using only the graphite block 10. Therefore, when mounting components on the lower surface 102 of the heat dissipation member 100, the reliability of mounting can be improved. The same applies to the upper surface 101 of the heat dissipation member 100.

[0029] Furthermore, according to this configuration, of a pair of adjacent graphite blocks 10, the second direction A2 of one graphite block 10 and the second direction A2 of the other graphite block 10 intersect with each other, which reduces the application of a force by one graphite block 10 to the other graphite block 10 in a direction that causes the other graphite block 10 to cleave. In other words, the anisotropy of the brittleness of substrate 110 is reduced, so that substrate 110 is less likely to deform even if external forces are applied to substrate 110 in various directions. Therefore, substrate 110 with high toughness can be obtained.

[0030] The number of the graphite blocks 10 is not particularly limited, but may be three or more. That is, the base material 110 may include at least a first graphite block 10a, a second graphite block 10b, and a third graphite block 10c. This configuration increases the rigidity of the base material 110 compared to when the number of graphite blocks 10 constituting the base material 110 is less than three.

[0031] As shown in FIGS. 2 and 6 , multiple graphite blocks 10 may be bonded to each other via a first bonding material 20. The first bonding material 20 may be formed in a sheet shape during the manufacturing process of the substrate 110. In this configuration, the sheet-shaped first bonding material 20 may be sandwiched between the graphite blocks 10 and then subjected to a heating process and a cooling process to provide a brazing effect. With this configuration, even if the first surface 11 and the second surface 12 of the graphite blocks 10 have large areas, the adhesion between the graphite blocks 10 via the first bonding material 20 can be improved. The improved adhesion can reduce the thermal resistance between one graphite block 10 and the other graphite block 10 of a pair of adjacent graphite blocks 10 (e.g., adjacent in the Z direction) compared to a configuration in which a gap is present.

[0032] <First Plate and Second Plate> <Linear Expansion Coefficient of First Plate and Second Plate> The linear expansion coefficient of the first plate 120 may be highly isotropic compared to that of the graphite block 10. The linear expansion coefficients of the first plate 120 in the X direction and the Y direction may be smaller than the linear expansion coefficient of the graphite block 10 in the first direction A1. The linear expansion coefficients of the first plate 120 in the X direction and the Y direction may be larger than the linear expansion coefficient of the graphite block 10 in the second direction A2. The linear expansion coefficient of the first plate 120 in the Z direction may be larger than the linear expansion coefficient of the graphite block 10 in the third direction A3. The same applies to the second plate 130.

[0033] The linear expansion coefficients of the first plate member 120 and the second plate member 130 may be, for example, 4.0 [10^-6 / K] or more and less than 20 [10^-6 / K], or even 6.0 [10^-6 / K] or more and less than 18 [10^-6 / K]. The first plate member 120 and the second plate member 130 may be made of a material having a linear expansion coefficient of 4.0 [10^-6 / K] or more and less than 20 [10^-6 / K], such as a metal material such as copper or stainless steel, or a ceramic material such as aluminum nitride, alumina, or zirconia. Furthermore, for example, if the linear expansion coefficient of the graphite block 10 is 24 [10^-6 / K] or more in the first direction A1, the first plate member 120 and the second plate member 130 may be made of a metal material having a linear expansion coefficient greater than that of copper, such as aluminum.

[0034] The linear expansion coefficients of the first plate member 120 and the second plate member 130 are compared with the linear expansion coefficient of the graphite block 10 using the linear expansion coefficients measured while changing the temperature from 20°C to 100°C. The linear expansion coefficients are measured using a measurement method specified in JIS depending on the material. For example, if the first plate member 120 and the second plate member 130 are made of a metal material, the measurement method specified in JIS Z 2285:2003 is used. If the first plate member 120 and the second plate member 130 are made of a ceramic material, the measurement method specified in JIS R 1618:2002 is used. The linear expansion coefficient of the graphite block 10 is measured using the measurement method specified in JIS R 1618:2002, mutatis mutandis.

[0035] <Thermal Conductivity of First Plate and Second Plate> The thermal conductivity of the first plate 120 and the second plate 130 may be highly isotropic compared to that of the graphite block 10. Furthermore, the thermal conductivity of the first plate 120 and the second plate 130 may be higher than the thermal conductivity of the graphite block 10 in the first direction A1. With this configuration, when heat is applied to a portion of the second plate 130 from outside the heat dissipation member 100, the heat is isotropically dispersed in the second plate 130 and then conducted to the base material 110. Then, in the base material 110, the heat is quickly dispersed in the second direction A2 and the third direction A3, which have high thermal conductivity, in each graphite block 10. The heat is then conducted to the first plate 120 and isotropically dispersed in the first plate 120. As described above, even when heat is applied to a portion of the second plate 130, the heat can be dispersed over a wide area of ​​the base material 110. Therefore, the heat dissipation member 100 can achieve efficient heat transfer performance.

[0036] <Materials of First Plate and Second Plate> The material of the first plate 120 may be a copper-based metal or alloy, such as oxygen-free copper. This configuration provides high thermal conductivity for the first plate 120, enabling the heat dissipation member 100 to achieve more efficient heat transfer performance. The first plate 120 may be a metal with high thermal conductivity, such as aluminum. Even with this configuration, the high thermal conductivity allows the heat dissipation member 100 to achieve efficient heat transfer performance. From the viewpoint of heat transfer, copper has better properties than aluminum.

[0037] The first plate member 120 may be made of ceramics such as alumina ceramics, silicon nitride ceramics, and aluminum nitride ceramics. The use of ceramics can meet the requirement for insulation of the heat dissipation member 100. When ceramics is used, the material of the first plate member 120 may be alumina ceramics or silicon nitride ceramics. The use of such a material provides high rigidity that resists the residual stress of the graphite block 10. Furthermore, the material of the first plate member 120 may be silicon nitride ceramics. The use of such a material can impart high thermal conductivity to the first plate member 120 in addition to rigidity, thereby achieving more efficient heat transfer performance of the heat dissipation member 100.

[0038] The above-described materials for the first plate 120 can be similarly applied to the second plate 130. The second plate 130 also exhibits the same effects as when the above-described materials are applied to the first plate 120.

[0039] <Hardness of First Plate and Second Plate> The hardness of the first plate 120 and the second plate 130 may be higher than the hardness of the graphite block 10. With this configuration, even if an external force is applied to the first plate 120 and the second plate 130, the external force is dispersed and acts on the graphite block 10. Therefore, damage to the graphite block 10 inside the first plate 120 and the second plate 130 can be suppressed.

[0040] The hardness may be measured by Vickers hardness. The hardness of graphite block 10 may be 10 MPa or more and 40 MPa or less in Vickers hardness. The hardness of first plate member 120 and second plate member 130 may be preferably 10 times or more, more preferably 20 times or more, the hardness of graphite block 10. The hardness of first plate member 120 and second plate member 130 may be preferably 200 MPa or more in Vickers hardness, more preferably 500 MPa or more, and even more preferably 900 MPa or more in Vickers hardness.

[0041] The Vickers hardness of the first plate member 120 and the second plate member 130 can be measured using the measurement method specified in JIS Z 2244:2009. The Vickers hardness of the graphite block 10 is a value converted from the measurement results of a nanoindentation test with a load of 20 mN / 10 seconds. Examples of materials having a hardness 10 times or more that of the graphite block 10 include various metal materials such as copper, aluminum, and stainless steel, and ceramic materials such as aluminum nitride, alumina, and zirconia. Furthermore, materials having a hardness 10 times or more that of the graphite block 10 are not limited to metal materials and ceramic materials, and various materials such as resin materials may also be used. In this disclosure, the Vickers hardness is expressed as a value obtained by converting the unit HV into pressure.

[0042] <Joining of First Plate and Second Plate to Base Material> First plate 120 and second plate 130 may be joined to first surface 111 and second surface 112, respectively, of base material 110. First surface 111 and second surface 112 may be surfaces extending in first direction A1. With this configuration, first plate 120 and second plate 130 are joined to their crystal layer surfaces. Therefore, first plate 120 and second plate 130 can reduce the force applied to graphite block 10 in a direction that causes it to cleave.

[0043] If the first plate material 120 and the second plate material 130 were bonded to each other at their crystal planes, the graphene on the crystal planes would easily peel off due to stress generated during bonding. In this case, even during use, if external forces are applied to the first plate material 120 and the second plate material 130 from various directions, there is a risk that the first plate material 120 or the second plate material 130 will peel off together with the graphene on its surface. However, by bonding the first plate material 120 and the second plate material 130 to each other at their crystal layer planes, the peeling of the graphene can be suppressed. Therefore, the toughness of the heat dissipation member 100 can be improved.

[0044] Second surface 112 to which second plate 130 is bonded may be the crystal layer surface with the largest area among the four crystal layer surfaces of graphite block 10 adjacent to second plate 130. This configuration can improve the stability of mounting a heat source to heat dissipation member 100. When two surfaces located opposite each other are referred to as a pair of surfaces, a configuration may be adopted in which the plate is positioned on two pairs of surfaces (i.e., four surfaces) of graphite block 10 adjacent to the plate via second bonding material 140. In this case, the remaining pair of surfaces (i.e., two surfaces) may be covered with protective layer 150. The two pairs of surfaces on which the plate is positioned via second bonding material 140 may be crystal layer surfaces. The pair of surfaces covered with protective layer 150 may be crystal surfaces. This configuration also achieves the same effect of increasing the toughness of heat dissipation member 100 described above.

[0045] <First Plate and Cooling Fins> Fig. 7 is a perspective view of the first plate 120 and the cooling fins 126. Fig. 8 is a perspective view showing a modified example of the first plate and the cooling fins. The first plate 120 may have a plurality of cooling fins 126. As shown in Fig. 7, the cooling fins 126 may be formed separately from the first plate 120. Furthermore, the first plate 120 may be provided with holes 123 into which the cooling fins 126 can be inserted. Furthermore, the holes 123 may penetrate in the Z direction (the thickness direction of the first plate 120).

[0046] When the cooling fins 126 are inserted into the holes 123, gaps may be formed between the peripheries of the holes 123 and the side surfaces of the cooling fins 126. Specifically, as shown in Fig. 7 , when the shape of the holes 123 is circular in a plan view (when viewed from the Z direction) and the shape of the cooling fins 126 is cylindrical, the diameter of the holes 123 may be larger than the diameter of the cooling fins 126.

[0047] As shown in FIG. 2 , the cooling fins 126 may be bonded to the first plate member 120 via a third bonding material 128. The third bonding material 128 may be made of the same material as the second bonding material 140. Furthermore, the third bonding material 128 may be continuous with the second bonding material 140. The third bonding material 128 may be made of the same material as the first bonding material 20. If a gap is formed between the periphery of the hole 123 and the side surface of the cooling fin 126, the gap may be filled with the third bonding material 128. With this configuration, when the heat dissipation member 100 is used as a water-cooled heat sink, cooling water flowing on the first plate member 120 (between the cooling fins 126) can be prevented from penetrating into the interior of the heat dissipation member 100 (the substrate 110 side) through the gap between the hole 123 and the cooling fin 126.

[0048] The number of holes 123 and cooling fins 126 may be other than 12. The shape of the cooling fins 126 may be other than cylindrical. The shape of the holes 123 may be appropriately changed to match the shape of the cooling fins 126. Regardless of the shape of the cooling fins 126, a gap may be formed between the periphery of the holes 123 and the side of the cooling fins 126 when the cooling fins 126 are inserted into the holes 123. Specifically, as shown in FIG. 8 , the first plate member of the heat dissipation member 100 may be a first plate member 120A having a plurality of holes 123A that are rectangular in plan view, and the cooling fins of the first plate member may be plate-shaped cooling fins 126A that can be inserted into the holes 123A.

[0049] The material of the cooling fins 126 may or may not be the same as the material of the first plate 120. When the cooling fins 126 and the first plate 120 are formed separately, it is easy to make the material of the cooling fins 126 different from the material of the first plate 120. Furthermore, the thickness of the first plate 120 may be the same as the thickness of the second plate 130.

[0050] When the cooling fins 126 and the first plate 120 are integrally formed, the volume of the first plate 120 includes the volume of the cooling fins 126, and therefore the volume of the first plate 120 is larger than the volume of the second plate 130. Therefore, in this case, in the step of joining the first plate 120 and the second plate 130 to the graphite base material (heating step), the first plate 120 expands more than the second plate 130, making the graphite base material more susceptible to warping due to temperature changes. In contrast, by using, as the graphite base material, a substrate 110 having a structure in which at least three graphite blocks 10 are stacked in the Z direction, one of the adjacent graphite blocks 10 having a structure in which a plurality of graphenes are stacked in the X direction and the other graphite block 10 having a structure in which a plurality of graphenes are stacked in the Y direction, it is possible to suppress the occurrence of warping due to temperature changes.

[0051] Furthermore, when the cooling fins 126 and the first plate 120 are formed separately, i.e., when the cooling fins 126 are fixed to the first plate 120 via a bonding material (third bonding material 128), the volume of the first plate 120 does not include the volume of the cooling fins 126. Therefore, when the cooling fins 126 and the first plate 120 are formed separately, the difference in volume between the first plate 120 and the second plate 130 is smaller than when the cooling fins 126 and the first plate 120 are formed integrally. In other words, by forming the cooling fins 126 and the first plate 120 separately, the degree of expansion of the first plate 120 can be made closer to the degree of expansion of the second plate 130, so that warping due to temperature changes can be more effectively suppressed.

[0052] Furthermore, by forming a gap between the periphery of the hole 123 and the cooling fin 126 when the cooling fin 126 is inserted into the hole 123, expansion and contraction of the first plate 120 due to thermal changes can be prevented from being restricted by the cooling fin 126. Therefore, the effect of forming the cooling fin 126 and the first plate 120 as separate bodies can be fully exerted, and warping due to temperature changes can be more effectively prevented. Furthermore, by forming a gap between the periphery of the hole 123 and the cooling fin 126 when the cooling fin 126 is inserted into the hole 123, the cooling fin 126 can be maintained inserted into the hole 123 even if the first plate 120 and the cooling fin 126 expand during the process of joining the first plate 120 and the second plate 130 to the base material 110 (heating process).

[0053] It is also possible to join the cooling fins 126 to the upper surface 121 of the first plate 120 without providing the holes 123 in the first plate 120. However, in this case, there is a problem that it is difficult to position the cooling fins 126. In contrast, by providing the holes 123 in the first plate 120, it becomes possible to position the cooling fins 126 simply by inserting the cooling fins 126 into the holes 123, making it easier to position the cooling fins 126.

[0054] <<Second Bonding Material>> The first plate member 120 may be bonded to the first surface 111 via the second bonding material 140. The second plate member 130 may be bonded to the second surface 112 via the second bonding material 140. A brazing material or a solder may be applied to the second bonding material 140. The second bonding material 140 may be configured to cover the bonding surfaces of the first plate member 120 and the second plate member 130 (i.e., clad) during the manufacturing stage of the heat dissipation member 100. This configuration allows the bonding material after bonding to be made thinner. Therefore, the thermal resistance of the second bonding material 140 can be reduced.

[0055] The second bonding material 140 may be configured to be formed into a sheet shape during the manufacturing stage of the heat dissipation member 100. In this configuration, the sheet-shaped second bonding material 140 may be sandwiched between the first plate member 120 and the base material 110 and then subjected to a heating process and a cooling process to exert a brazing effect. The same applies to the second plate member 130. With this configuration, even if the first surface 111 and the second surface 112 of the base material 110 have large areas, the adhesion between the first plate member 120 and the base material 110 via the second bonding material 140 can be improved. Similarly, the adhesion between the second plate member 130 and the base material 110 via the second bonding material 140 can be improved. By improving the adhesion, the thermal resistance between the first plate member 120 and the base material 110 and the thermal resistance between the second plate member 130 and the base material 110 can be reduced compared to a configuration in which a gap is present.

[0056] The second bonding material 140 may be referred to as an intervening layer. The second bonding material 140 may be located only in a partial region of the first surface 111 and a partial region of the second surface 112. A thermally conductive grease or the like may be filled as an intervening layer in the range other than the region where the second bonding material 140 is located so as to prevent a gap from occurring between the first plate material 120 and the base material 110 or between the second plate material 130 and the base material 110.

[0057] <<Protective Layer>> Protective layer 150 may cover side surface 113 of substrate 110. Side surface 113 may include a first side surface 113a extending in the X direction and a second side surface 113b extending in the Y direction. As shown in FIGS. 1B , 1C , and 6 , among the side surfaces of graphite block 10, third surface 13, which is a crystal plane, and fourth surface 14, which is a crystal layer plane, may be located on first side surface 113a of substrate 110. Similarly, among the side surfaces of graphite block 10, third surface 13, which is a crystal plane, and fourth surface 14, which is a crystal layer plane, may be located on second side surface 113b of substrate 110. That is, the substrate 110 has a plurality of side surfaces 113 (for example, two first side surfaces 113a located opposite each other and two second side surfaces 113b located opposite each other), and each side surface 113 may have both a third surface 13 which is a crystal plane and a fourth surface 14 which is a crystal layer plane.

[0058] 1B and 1C, the third surfaces 13 of the first graphite block 10a and the third graphite block 10c and the fourth surface 14 of the second graphite block 10b are located on the first side surface 113a. Also, the fourth surfaces 14 of the first graphite block 10a and the third graphite block 10c and the third surface 13 of the second graphite block 10b are located on the second side surface 113b.

[0059] This configuration can prevent the protective layer 150 from peeling off from the substrate 110. As shown in FIGS. 4 and 5 , the fourth surface 14, which is a crystal layer surface, has more irregularities than the third surface 13, which is a crystal surface. On the fourth surface 14, a portion of the protective layer 150 is located within the recess F1 of the irregularities of the fourth surface 14. That is, the fourth surface 14, which is a crystal layer surface, has more irregularities that exert an anchoring effect than the third surface 13, which is a crystal surface. Therefore, by positioning the fourth surface 14 on each side surface 113 of the substrate 110, the anchoring effect works, improving the adhesion of the protective layer 150 to the side surface 113. This prevents the protective layer 150 from peeling off from the substrate 110. Furthermore, by positioning the protective layer 150 within the recess F1 of the irregularities, the thermal resistance between the protective layer 150 and the graphite block 10 can be reduced compared to a configuration in which a gap is generated in the recess F1.

[0060] The protective layer 150 may be a plating layer of nickel or gold, a resin film, or a ceramic film. By employing a plating layer, the protective layer 150 can have high thermal conductivity, contributing to the efficient heat transfer performance of the heat dissipation member 100. Furthermore, when the heat dissipation member 100 is required to have electrical conductivity, this requirement can be met. The protective layer 150 may also be made up of multiple layers. For example, the protective layer 150 may include a surface Au (gold) layer and an underlying Ni (nickel) layer. The metal layer used for the protective layer 150 is not limited to this, and various metals may be used.

[0061] The protective layer 150 may cover the side surface 113 as well as the side surface 122 of the first plate 120 (see FIGS. 1B and 2 ) and the side surface 132 of the second plate 130 (see FIGS. 1B and 2 ). The edges of the protective layer 150 are more susceptible to peeling than other portions. On the other hand, the side surface 122 of the first plate 120 and the side surface 132 of the second plate 130 are more likely to adhere the protective layer 150 with higher strength than the side surface 113 of the substrate 110. Therefore, by having the protective layer 150 cover a portion of the first plate 120 and the second plate 130, the edges of the protective layer 150 are located on the surfaces of the first plate 120 and the second plate 130, thereby preventing peeling of the protective layer 150. Furthermore, the protective layer 150 is continuous from the surfaces of the first plate 120 and the second plate 130 to the side surface 113 of the substrate 110. Therefore, peeling of the protective layer 150 can be suppressed, including the region of the side surface 113 of the substrate 110 .

[0062] The protective layer 150 may further cover a portion of the upper surface 121 of the first plate 120. The protective layer 150 may further cover a portion of the lower surface 131 of the second plate 130. The upper surface 121 of the first plate 120 is the surface opposite to the surface facing the base material 110. The lower surface 131 of the second plate 130 is the surface opposite to the surface facing the base material 110. Even with this configuration, peeling of the protective layer 150 can be suppressed as described above.

[0063] When the protective layer 150 covers the upper surface 121 of the first plate 120, the upper surface 101 of the heat dissipation member 100 may correspond to the surface of the protective layer 150. When the protective layer 150 does not cover the upper surface 121 of the first plate 120, the upper surface 101 of the heat dissipation member 100 may correspond to the upper surface 121 of the first plate 120. When the protective layer 150 covers the lower surface 131 of the second plate 130, the lower surface 102 of the heat dissipation member 100 may correspond to the surface of the protective layer 150. When the protective layer 150 does not cover the lower surface 131 of the second plate 130, the lower surface 102 of the heat dissipation member 100 may correspond to the lower surface 131 of the second plate 130.

[0064] The protective layer 150 may further cover a portion of the exposed surface of the cooling fin 126. The protective layer 150 may further cover a portion of the exposed surface of the third bonding material 128. Here, the exposed surface of the cooling fin 126 refers to a visible region of the cooling fin 126 in a state in which the cooling fin 126 is fixed to the first plate member 120 via the third bonding material 128. The exposed surface of the third bonding material 128 refers to a visible region of the solidified third bonding material 128 in a state in which the cooling fin 126 is fixed to the first plate member 120 via the third bonding material 128.

[0065] The protective layer 150 may further cover the entire exposed surface of the cooling fins 126, the entire exposed surface of the third bonding material 128, the entire side surface 122 and upper surface 121 of the first plate member 120, the entire side surface 113 of the base material 110, and the entire side surface 132 and lower surface 131 of the second plate member 130. Figures 1A and 2 show this configuration. With this configuration, the edge portions of the protective layer 150 are reduced (e.g., eliminated), thereby further suppressing peeling and damage of the protective layer 150. Furthermore, with this configuration, the complexity of the process of forming the protective layer 150 can be reduced.

[0066] When the protective layer 150 covers at least a portion of the lower surface 131 of the second plate 130, a material with high thermal conductivity, such as a metal plating layer, may be applied to the protective layer 150. With this configuration, even when a heat source comes into contact with the heat dissipation member 100 through the protective layer 150, heat can be quickly conducted to the second plate 130 through the protective layer 150.

[0067] The thermal conductivity of the protective layer 150 may be highly isotropic compared to that of the graphite block 10. The thermal conductivity of the protective layer 150 may be higher than the thermal conductivity of the graphite block 10 in the first direction A1. This configuration provides an effect of dispersing heat in the first direction A1 via the protective layer 150 at the fourth surface 14. Therefore, the addition of this dispersion effect allows the heat dissipation member 100 to achieve more efficient heat transfer performance.

[0068] 9A is a diagram showing a first example of use of the heat dissipation member 100, and Fig. 9B is a diagram showing a second example of use of the heat dissipation member 100. The heat dissipation member 100 may be replaced with the heat dissipation member 100A of the second embodiment described below.

[0069] The heat dissipation member 100 may be used as a water-cooled heat sink, as shown in Fig. 9A. Specifically, the electronic device 300 shown in Fig. 9A is an electronic device incorporating the heat dissipation member 100, and includes the heat dissipation member 100, a water-cooling jacket 310, a submount substrate 330 such as a circuit board, and an electronic element 350 such as a semiconductor chip. The heat dissipation member 100 is arranged so that the cooling fins 126 come into contact with the cooling water flowing inside the water-cooling jacket 310.

[0070] The submount substrate 330 may be mounted on the lower surface 102 of the heat dissipation member 100 via a bonding material 320 such as solder. The electronic element 350 may be mounted on the submount substrate 330 via a bonding material 340 such as solder. That is, the electronic element 350 and the second plate member 130 of the heat dissipation member 100 may be thermally connected via the submount substrate 330. With this configuration, heat from the electronic element 350, which is a heat source, can be quickly transferred to the heat dissipation member 100 via the submount substrate 330.

[0071] In the electronic device 300, heat from the electronic element 350 is first transferred to the second plate 130 of the heat dissipation member 100 via the submount substrate 330, and then transferred to the first plate 120 (including the cooling fins 126) of the heat dissipation member 100 via the base material 110 of the heat dissipation member 100. With this configuration, the heat from the electronic element 350 can be quickly transferred from the second plate 130 to the first plate 120 (including the cooling fins 126) via the base material 110 containing a carbon material, and can be released from the first plate 120 (including the cooling fins 126) to the cooling water flowing inside the water-cooled jacket 310.

[0072] The submount substrate 330 may be made of an insulating material such as a ceramic material. This configuration ensures insulation between the heat dissipation member 100 and the electronic element 350. The material of the submount substrate 330 may be silicon nitride ceramic. This configuration ensures insulation between the heat dissipation member 100 and the electronic element 350 and also provides high toughness to the submount substrate 330. Furthermore, this configuration provides high toughness to the submount substrate 330, making it easier to thin the submount substrate 330. The material of the submount substrate 330 may also be alumina ceramic. This configuration ensures insulation between the heat dissipation member 100 and the electronic element 350 and also provides high strength to the submount substrate 330. Therefore, it is easier to thin the submount substrate 330. The material of the submount substrate 330 may also be aluminum nitride ceramic. This configuration ensures insulation between the heat dissipation member 100 and the electronic element 350, and also provides high thermal conductivity to the submount substrate 330. Note that the submount substrate 330 may be made of a semiconductor material such as silicon carbide (SiC).

[0073] The heat dissipation member 100 may be used as an air-cooled heat sink as shown in Fig. 9B. Specifically, the electronic device 400 shown in Fig. 9B is an electronic device incorporating the heat dissipation member 100, and includes the heat dissipation member 100, a fan 410, a cap 430, an electronic element 450 such as a semiconductor chip, and a circuit board 460. The heat dissipation member 100 may be arranged so that the air from the fan 410 hits the cooling fins 126.

[0074] The cap 430 may be in contact with the lower surface 102 of the heat dissipation member 100 via a bonding material 420 such as highly thermally conductive grease. A metal material may be used for the cap 430. The electronic element 450 may be in contact with the cap 430 via a bonding material 440 such as highly thermally conductive grease. In other words, the electronic element 450 and the second plate member 130 of the heat dissipation member 100 may be thermally connected via the cap 430. With this configuration, heat from the electronic element 450, which is a heat source, can be quickly conducted to the heat dissipation member 100 via the cap 430.

[0075] In the electronic device 400, heat from the electronic element 450 is first transferred to the second plate 130 of the heat dissipation member 100 via the cap 430, and then transferred to the first plate 120 (including the cooling fins 126) of the heat dissipation member 100 via the substrate 110 of the heat dissipation member 100. This configuration allows the heat from the electronic element 450 to be quickly transferred from the second plate 130 to the first plate 120 (including the cooling fins 126) via the substrate 110 containing a carbon material, and then released from the first plate 120 (including the cooling fins 126) into the space between the first plate 120 and the fan 410. As a result, the heat from the electronic element 450 is released by the fan 410, for example, to the outside of the electronic device 400. The electronic element 450 may be mounted on a circuit board 460. The circuit board 460 may be an organic circuit board.

[0076] A heat source other than the electronic elements 350 and 450 may be mounted on the lower surface 102 of the heat dissipation member 100. That is, various heat sources, such as the electronic elements 350 and 450, a heat pipe for exhausting heat, and a heater for heating, can be mounted on the lower surface 102 of the heat dissipation member 100. As described above, the heat dissipation member 100 is a heat dissipation member containing highly thermally conductive graphite, and therefore has improved heat dissipation performance compared to heat dissipation members made of metal. Furthermore, since only the base material 110 of the heat dissipation member 100 is made of highly thermally conductive graphite, costs can be reduced compared to heat dissipation members made of graphite (heat dissipation members made entirely of highly thermally conductive graphite).

[0077] [Embodiment 2] Figures 10A, 10B, and 10C are diagrams showing an example of a heat dissipation member 100A according to embodiment 2 of the present disclosure. Figure 10A is a perspective view of the heat dissipation member 100A, Figure 10B is a perspective view of the configuration excluding the protective layer 150, and Figure 10C is a perspective view of the base material 110A (a perspective view of the configuration excluding the protective layer 150, the first plate material 120, the cooling fins 126, and the second plate material 130). Figure 11 is an exploded perspective view of the base material 110A. Figures 12A and 12B are cross-sectional views showing an example of the heat dissipation member 100A. The heat dissipation member 100A of embodiment 2 differs from embodiment 1 in the configuration of the base material 110A, but the other configurations may be similar to embodiment 1. The differences will be described in detail below.

[0078] Substrate 110A may have a structure in which a plurality of graphite blocks 10A are stacked in the Z direction. Graphite block 10A may include a plurality of rectangular graphite materials 16. Graphite material 16 refers to a structure that becomes a single piece when the bond to the surrounding area by the bonding material is released.

[0079] It is not easy to prepare a single large graphite block. In the second embodiment, by adopting a configuration in which graphite block 10A includes a plurality of graphite materials 16, it is possible to increase the dimensions of heat dissipation member 100A in the X direction or Y direction, thereby increasing the degree of freedom in designing heat dissipation member 100A.

[0080] The number of the plurality of graphite materials 16 is not particularly limited, but may be five or less. By setting the number to five or less, the proportion of regions with low thermal conductivity within the base material 110A can be reduced. The regions with low thermal conductivity are gaps G formed between a pair of adjacent graphite materials 16 or fourth bonding materials 17 located in gaps G.

[0081] As shown in Fig. 11 , the plurality of graphite materials 16 may be arranged side by side in the first direction A1 in which graphene is stacked. More specifically, as shown in Figs. 11 , 12A, and 12B, first graphite block 10aA may include a plurality of graphite materials 16 arranged side by side in first direction A1a and a fourth bonding material 17 positioned between adjacent pairs of graphite materials 16 and bonding the pair of graphite materials 16 together. Second graphite block 10bA may include a plurality of graphite materials 16 arranged side by side in first direction A1b and a fourth bonding material 17 positioned between adjacent pairs of graphite materials 16 and bonding the pair of graphite materials 16 together. Third graphite block 10cA may include a plurality of graphite materials 16 arranged side by side in first direction A1c and a fourth bonding material 17 positioned between adjacent pairs of graphite materials 16 and bonding the pair of graphite materials 16 together.

[0082] Gaps G are generated between the plurality of graphite materials 16. However, by arranging the plurality of graphite materials 16 in the first direction A1, it is possible to reduce the possibility that the gaps G will block the heat conduction path in the directions (second direction A2 and third direction A3) where the thermal conductivity of the graphite materials 16 is high. Therefore, it is possible to reduce the influence of the gaps G on the thermal conduction performance of the heat dissipation member 100A. Furthermore, as in the first embodiment, it is possible to generate a direction (i.e., the first direction A1) where the thermal conductivity is low throughout the graphite block 10A.

[0083] The gap G may be an air gap. Alternatively, the fourth bonding material 17 may be located in at least a portion of the gap G. Alternatively, the fourth bonding material 17 may almost fill the gap G (for example, the fourth bonding material 17 may be located in 90% or more of the cross section). The fourth bonding material 17 may be a brazing material, a solder material, or a resin material.

[0084] Fourth bonding material 17 may be made of the same material as second bonding material 140 that bonds first plate member 120 and second plate member 130 to base material 110A. Furthermore, fourth bonding material 17 may be continuous with second bonding material 140. Furthermore, fourth bonding material 17 may be made of the same material as third bonding material 128. Fourth bonding material 17 may be made of the same material as first bonding material 20 that bonds graphite blocks 10A together. Furthermore, fourth bonding material 17 may be continuous with first bonding material 20. Fourth bonding material 17 that is continuous with second bonding material 140 and fourth bonding material 17 that is continuous with first bonding material 20 may be made of the same material or different materials.

[0085] The facing direction of adjacent pairs of the plurality of graphite materials 16 is not limited to the above direction. The plurality of graphite materials 16 may be arranged so as to face each other in a direction different from the direction in which the graphene is stacked (for example, the second direction A2 or the third direction A3).

[0086] 13A, 13B, 14A, and 14B are diagrams illustrating an example of a method for manufacturing a heat dissipation member. The following describes a method for manufacturing the heat dissipation member 100A of embodiment 2. The manufacturing method includes a graphite processing step J1, a joining step J2, a cutting step J3, and a plating step J4.

[0087] In graphite processing step J1, graphite element 501 is cut using a processing machine such as a wire saw to produce a plurality of rectangular graphite materials 516. Graphite element 501 generally has two crystal planes, and the dimensions of the crystal planes are greater than the dimensions in the direction perpendicular to the crystal planes. Cut graphite material 516 may be cut so that the minimum width of the crystal planes is smaller than the minimum width of the cut surfaces (i.e., crystal layer surfaces).

[0088] In the bonding process J2, a plurality of graphite materials 516 are arranged in parallel and stacked in the orientation shown in embodiment 2. A first bonding material 502 is disposed between adjacent graphite materials 516 in the Z direction (stacking direction). A first plate material 520 and a second plate material 530 are then disposed between the plurality of graphite materials 516 with a second bonding material 140 (not shown) sandwiched therebetween. Cooling fins 126 are inserted into a plurality of holes formed in the first plate material 520. The first bonding material 502 and the second bonding material 140 are then bonded to each other by heating and cooling.

[0089] At this stage, the plurality of graphite materials 516 adjacent in the Z direction are bonded to one another by the first bonding material 502. The first bonding material 502 may infiltrate gaps G (see FIGS. 12A and 12B ) between the plurality of graphite materials 516 adjacent in a direction intersecting the Z direction, thereby bonding the plurality of graphite materials 516 to one another. This produces a graphite substrate. Also at this stage, the first plate material 520 and the second plate material 530 are bonded to the graphite substrate by the second bonding material 140, and the cooling fin 126 is bonded to the first plate material 520 by the third bonding material 128 (e.g., the third bonding material 128 is made of the same material as the second bonding material 140 and is continuous with the second bonding material 140). The second bonding material 140 may infiltrate into gaps G (see Figures 12A and 12B) between adjacent graphite materials 516 in a direction intersecting the Z direction, thereby bonding the graphite materials 516 to each other.

[0090] In the cutting process J3, the first plate material 520, the graphite substrate, and the second plate material 530, which are joined together, are cut to the dimensions of the first plate material 120, the substrate 110A, and the second plate material 130 of the heat dissipation member 100A using a processing machine such as a dicing machine or a wire saw.

[0091] In the plating step J4, plating is applied to the outside of the structure cut in the cutting step J3. The plating is performed so as to cover at least the side surface 113 of the base material 110A. The plating may be performed on the entire surface, including the outer surfaces of the first plate material 120 and the second plate material 130. As a result, the plated layer becomes the protective layer 150. The heat dissipation member 100A is manufactured by the above steps J1 to J4.

[0092] [Other Embodiments] The heat dissipation member is not limited to the above-described configuration. For example, in other embodiments, the linear expansion coefficients of the first and second plates may be greater than that of the graphite block in both the first and second directions. Resin materials such as ABS resin and polybutylene terephthalate (PBT) may be used as the materials for the first and second plates. When the linear expansion coefficient of the graphite block 10 is less than 24 [10^-6 / K] in the first direction A1, the first and second plates 120 and 130 may be made of a metal material, such as aluminum, whose linear expansion coefficient is greater than that of copper. Even in this case, the same or similar configuration as the above-described embodiment provides the same effects.

[0093] The above describes the embodiments of the present disclosure. However, the heat dissipation member of the present disclosure is not limited to the heat dissipation members 100 and 100A of the above-described embodiments. For example, the details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention. According to the present disclosure, a heat dissipation member with improved heat dissipation performance can be obtained.

[0094] An embodiment of the present disclosure is described below. In one embodiment, (1) a heat dissipation member includes: a base having a first surface extending in an X direction and a Y direction intersecting each other, a second surface opposite the first surface, and a side surface located between the first surface and the second surface and extending in a Z direction intersecting the X direction and the Y direction, a first plate member having a cooling fin and fixed to the first surface, and a second plate member fixed to the second surface, wherein the base has a structure in which at least three layers of graphite blocks are stacked in the Z direction, and among the adjacent graphite blocks, one graphite block has a structure in which a plurality of graphenes are stacked in the X direction, and the other graphite block has a structure in which a plurality of graphenes are stacked in the Y direction.

[0095] (2) In the heat dissipation member of (1) above, the cooling fins are fixed to the first plate member via a bonding material.

[0096] (3) In the heat dissipation member of (2) above, the first plate member has a hole into which the cooling fin can be inserted, there is a gap between the periphery of the hole and the cooling fin, and the bonding material fills the gap.

[0097] (4) In the heat dissipation member of any one of (1) to (3) above, the graphite block has a structure in which a plurality of strip-shaped graphite materials are arranged in parallel, and the parallel direction of the plurality of graphite materials is the same as the stacking direction of the graphene constituting the graphite materials.

[0098] (5) In the heat dissipation member according to any one of (1) to (4) above, the side surface is covered with a protective layer.

[0099] (6) In the heat dissipation member of any one of (1) to (5) above, the side surfaces include a first side surface extending along the X direction and a second side surface extending along the Y direction, a crystal layer surface of the one graphite block and a crystal layer surface of the other graphite block are located on the first side surface, and a crystal layer surface of the one graphite block and a crystal layer surface of the other graphite block are located on the second side surface.

[0100] (7) In the heat dissipation member according to any one of (1) to (6) above, the first plate member, the second plate member, and the cooling fins are made of metal.

[0101] In one embodiment, (8) an electronic device includes: the heat dissipation member according to any one of (1) to (7); and an electronic element connected to the second plate member.

[0102] The present disclosure can be used as a heat dissipation member and an electronic device.

[0103] REFERENCE SIGNS LIST 10, 10A Graphite block 16 Graphite material 100, 100A Heat dissipation member 110, 110A Base material 111 First surface 112 Second surface 113 Side surface 113a First side surface 113b Second side surface 120, 120A First plate material 126, 126A Cooling fin 123, 123A Hole 128 Third bonding material (bonding material) 130 Second plate material 150 Protective layer 300, 400 Electronic device 350, 450 Electronic element

Claims

1. A substrate having a first surface extending along the X and Y directions which intersect each other, a second surface facing the first surface, and a side surface located between the first surface and the second surface and extending along the Z direction which intersects the X and Y directions, A first plate material having cooling fins and fixed to the first surface, The system comprises a second plate material fixed to the second surface, The substrate has a structure in which graphite blocks are stacked in at least three layers in the Z direction. Among the graphite blocks adjacent to each other, One graphite block has a structure in which multiple graphenes are stacked in the X direction, The other graphite block is a heat dissipation member having a structure in which multiple graphenes are stacked in the Y direction.

2. The cooling fins are fixed to the first plate material via a bonding material. The heat dissipation member according to claim 1.

3. The first plate material is provided with a hole into which the cooling fins can be inserted. There is a gap between the periphery of the hole and the cooling fin. The aforementioned joining material fills the gap. The heat dissipation member according to claim 2.

4. The graphite block has a structure in which multiple strip-shaped graphite materials are arranged in parallel. The parallel orientation of the multiple graphite materials is the same as the stacking direction of the graphene constituting the graphite material. The heat dissipation member according to claim 1.

5. The aforementioned side is covered with a protective layer. The heat dissipation member according to claim 1.

6. The aforementioned side surface includes a first side surface extending along the X direction and a second side surface extending along the Y direction, The first side surface is located on the crystal layer surface of one graphite block and the crystal surface of the other graphite block. The second surface is located on the crystal plane of one graphite block and the crystal layer plane of the other graphite block. The heat dissipation member according to claim 5.

7. The first plate material, the second plate material, and the cooling fins are made of metal. The heat dissipation member according to claim 1.

8. The heat dissipation member according to claim 1, An electronic element connected to the second plate material, An electronic device equipped with the following features.