Heat transfer member and electronic apparatus

Abstract

To provide a heat transfer member having high heat transfer performance and toughness.SOLUTION: A heat transfer member comprises a plurality of graphite blocks having a structure in which a plurality of graphenes are laminated in a first direction and a protection structure for protecting the plurality of graphite blocks. The protection structure is physically and thermally connected to the plurality of graphite blocks. The graphite blocks have anisotropy of a heat transfer rate and a heat expansion rate. In the first direction, a heat transfer rate of the protection structure is larger than the heat transfer rate of the graphite block. In a direction crossing the first direction, a heat transfer rate of the graphite block is larger than the heat transfer rate of the protection structure. In the first direction, a heat expansion rate of the graphite block is larger than the heat expansion rate of the protection structure. In the direction crossing the first direction, the heat expansion rate of the protection structure is larger than the heat expansion rate of the graphite block. The protection structure has one plate material, and the plurality of graphite blocks are positioned side by side on one main surface of the plate material.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Conventionally, a technique using graphite as a heat transfer member has been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a material having high heat transfer performance, graphite blocks are known. However, a single graphite block has a problem of being brittle compared to metals such as copper.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a heat transfer member and an electronic device having high heat transfer performance and toughness.

Means for Solving the Problems

[0006] The heat transfer member of the present disclosure includes a plurality of graphite blocks and a protective structure. The graphite blocks have a structure in which a plurality of graphene sheets are stacked in a first direction. The protective structure protects the plurality of graphite blocks. The protective structure is physically and thermally connected to the plurality of graphite blocks. The graphite blocks have anisotropy in thermal conductivity and coefficient of thermal expansion. In the first direction, the thermal conductivity of the protective structure is greater than the thermal conductivity of the graphite blocks. In a direction orthogonal to the first direction, the thermal conductivity of the graphite blocks is greater than the thermal conductivity of the protective structure. In the first direction, the coefficient of thermal expansion of the graphite blocks is greater than the coefficient of thermal expansion of the protective structure. In a direction orthogonal to the first direction, the coefficient of thermal expansion of the protective structure is greater than the coefficient of thermal expansion of the graphite blocks. The protective structure has a single plate material. The plurality of graphite blocks are arranged side by side on one main surface of the plate material.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a heat transfer member and an electronic device having high heat transfer performance and toughness.

Brief Description of the Drawings

[0008]

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MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments for implementing the heat transfer member and the electronic device according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. Note that the present disclosure is not limited by these embodiments. Also, the respective embodiments can be appropriately combined as long as the processing contents do not conflict. In addition, in the following embodiments, the same parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0010] <Heat transfer member> First, the configuration of the heat transfer member 1 according to the embodiment will be described with reference to FIGS. 1 to 7. The heat transfer member 1 according to the embodiment (see FIG. 5) may include a plurality of graphite blocks 10. FIG. 1 is a perspective view showing an example of the configuration of the graphite block 10 according to the embodiment.

[0011] As shown in FIG. 1, the graphite block 10 may have a structure in which a plurality of graphene 11 are stacked in the first direction A1. The graphene 11 may be a sheet-like substance in which a honeycomb structure formed by bonding carbon atoms extends in a two-dimensional direction.

[0012] The graphene 11 may extend along a direction orthogonal to the first direction A1, for example, the second direction A2 and the third direction A3. In the graphite block 10, adjacent graphenes 11 may be bonded to each other by an intermolecular force that is a van der Waals force.

[0013] In each of the drawings referred to below, for the sake of easy understanding of the description, there may be cases where an orthogonal coordinate system composed of the first direction A1, the second direction A2, and the third direction A3 that are orthogonal to each other is shown.

[0014] The graphite block 10 may have a rectangular parallelepiped shape. The graphite block 10 may have a pair of first surfaces 10a, a pair of second surfaces 10b, and a pair of third surfaces 10c.

[0015] The first surface 10a may be a surface that intersects the first direction A1, for example, a surface orthogonal to the first direction A1. The first surface 10a may be a surface on which the graphene 11 spreads in a two-dimensional direction.

[0016] The second surface 10b is a surface that extends along the first direction A1, and may be, for example, a surface orthogonal to the third direction A3. The second surface 10b may be a surface on which layers of a plurality of graphenes 11 appear.

[0017] The third surface 10c is a surface that intersects the second surface 10b and extends along the first direction A1, and may be, for example, a surface orthogonal to the second direction A2. The third surface 10c may be a surface on which layers of a plurality of graphenes 11 appear, and may also be a surface having a smaller area than the second surface 10b.

[0018] Hereinafter, a surface on which the graphene 11 spreads in a two-dimensional direction, for example, the first surface 10a, is also referred to as a "crystal plane", and a surface on which layers of the graphene 11 appear, for example, the second surface 10b and the third surface 10c, are also referred to as "crystal layer planes". Also, in each drawing referred to below, the "crystal plane" is represented by a honeycomb pattern, and the "crystal layer plane" is represented by a striped pattern.

[0019] The graphite block 10 may have anisotropy in properties related to brittleness. As the anisotropy in properties related to brittleness, the graphite block 10 may have a property of being easily cleaved with respect to a surface on which the graphene 11 spreads in a two-dimensional direction, that is, a surface intersecting the first direction A1. Cleavage means cracking along a certain surface.

[0020] Furthermore, as the anisotropy in properties related to brittleness, the graphite block 10 may have a property that when stress is generated along the plane direction of the crystal plane, the graphene 11 located on the crystal plane is easily peeled off.

[0021] Furthermore, the graphite block 10 may have a property that the edge portion E1 of the graphene 11 shown in FIG. 2 is weak and is liable to break from the edge portion E1. FIG. 2 is an enlarged cross-sectional view showing an example of the configuration of the first surface 10a of the graphite block 10 according to the embodiment.

[0022] As a specific material, the main component of the graphite block 10 may be pyrolytic graphite. In the present disclosure, the "main component" means, for example, that the volume ratio is 50% or more.

[0023] Pyrolytic graphite may be manufactured, for example, as follows. For example, hydrocarbons are vapor-deposited and laminated, and then pyrolytic graphite is manufactured by performing a pressure annealing treatment.

[0024] The graphite block 10 may have anisotropy in thermal conductivity and thermal expansion coefficient. The graphite block 10 may have a very high thermal conductivity in the direction along the crystal plane, for example, the second direction A2 and the third direction A3.

[0025] The thermal conductivity of the second direction A2 and the third direction A3 in the graphite block 10 may be, for example, 200 W / m·K or more.

[0026] On the other hand, the thermal conductivity of the first direction A1 in the graphite block 10 may be a value lower than the thermal conductivity of the second direction A2 or the third direction A3, for example, 7 W / m·K.

[0027] The thermal conductivity of the second direction A2 and the third direction A3 in the graphite block 10 may preferably be 370 W / m·K or more, more preferably 450 W / m·K or more, and still more preferably 800 W / m·K or more.

[0028] In the embodiment, the thermal conductivity of the second direction A2 and the third direction A3 in the graphite block 10 may be 1200 W / m·K or more, and more specifically, about 1700 W / m·K.

[0029] Also, the graphite block 10 may have a very high coefficient of thermal expansion in the direction along the first direction A1. The coefficient of thermal expansion of the graphite block 10 in the first direction A1 may be, for example, 20×10 -6 / K or more. In the present disclosure, when simply described as "coefficient of thermal expansion", it means the coefficient of linear expansion.

[0030] The coefficient of thermal expansion of the graphite block 10 in the first direction A1 may preferably be 24×10 -6 / K. Also, the coefficient of thermal expansion of the graphite block 10 in the first direction A1 may be 27×10 -6 / K or less.

[0031] On the other hand, the coefficients of thermal expansion of the graphite block 10 in the directions along the crystal planes, for example, the second direction A2 and the third direction A3, may be lower values than the coefficient of thermal expansion in the first direction A1, for example, 0.050×10 -6 / K or the like.

[0032] In addition, the coefficients of thermal expansion of the graphite block 10 in the second direction A2 and the third direction A3 may be negative values. Specifically, they may be -0.001×10 -6 / K or less. The coefficients of thermal expansion of the graphite block 10 in the second direction A2 and the third direction A3 may be -0.01×10 -6 / K or more.

[0033] In the graphite block 10, the surface roughness of the first surface 10a which is a crystal plane may be smaller than the surface roughnesses of the second surface 10b and the third surface 10c which are crystal layer planes. Specifically, the surface roughnesses of the second surface 10b and the third surface 10c may be 20 times or more the surface roughness of the first surface 10a, or may be more than 10 times and less than 20 times, or may be more than 5 times and less than 10 times.

[0034] In the present disclosure, the "surface roughness" means the arithmetic mean roughness Ra defined in JIS_B_0601:2001.

[0035] In this way, by reducing the surface roughness of the first surface 10a, the edge portion E1 of the graphene 11 appearing on the first surface 10a (see FIG. 2) is reduced. Therefore, according to the embodiment, the brittleness of the first surface 10a can be reduced.

[0036] FIG. 3 is an enlarged cross-sectional view showing an example of the configuration of the second surface 10b and the third surface 10c of the graphite block 10 according to the embodiment. As shown in FIG. 3, the second surface 10b and the third surface 10c of the graphite block 10 may include relatively large irregularities due to the above surface roughness and may have recesses F1. In the present disclosure, the irregularities included in the second surface 10b and the third surface 10c may be fine irregularities.

[0037] FIG. 4 is a perspective view showing an example of the arrangement of a plurality of graphite blocks 10 included in the heat transfer member 1 according to the embodiment. As shown in FIG. 4, in the embodiment, the heat transfer member 1 (see FIG. 5) may have a plurality of, in the figure, three graphite blocks 10. Thereby, the degree of freedom in the design of the heat transfer member 1 can be increased.

[0038] Further, in the embodiment, as shown in FIG. 4, a plurality of graphite blocks 10 included in the heat transfer member 1 may be arranged in a row such that the first surfaces 10a (see FIG. 1) of each other face each other.

[0039] That is, in the heat transfer member 1 according to the embodiment, a plurality of graphite blocks 10 may be arranged in a row along the first direction A1. In the heat transfer member 1 according to the embodiment, the spaces between adjacent graphite blocks 10 may be in close contact with each other, or may have a slight gap.

[0040] In the present disclosure, the plurality of graphite blocks 10 may also be manufactured by cutting a graphite block of a larger size along the stacking direction of the graphene 11 using a processing machine such as a wire saw.

[0041] In each of the subsequent drawings, an example is shown in which a plurality of graphite blocks 10 of the same size are arranged side by side along the first direction A1. However, the present disclosure is not limited to such an example. For example, in the present disclosure, a plurality of graphite blocks 10 may be arranged side by side along the second direction A2 or the third direction A3.

[0042] Also, in the present disclosure, a plurality of graphite blocks 10 of different sizes may be arranged side by side. Further, in the present disclosure, the heat transfer member 1 may include two or four or more graphite blocks 10.

[0043] FIG. 5 is a perspective view showing an example of the configuration of the heat transfer member 1 according to the embodiment. FIG. 6 is a cross-sectional view taken along the line A-A shown in FIG. 5. As shown in FIGS. 5 and 6, the heat transfer member 1 according to the embodiment may include a plurality of graphite blocks 10, a protective structure 20, and a bonding material 30. Note that in FIG. 5, the illustration of the bonding material 30 is omitted.

[0044] The protective structure 20 protects the plurality of graphite blocks 10. The protective structure 20 may have a plate member 21A and a plate member 21B. The plate member 21B is an example of another plate member.

[0045] As shown in FIG. 6, the main surface 21A1 of the plate member 21A may be positioned to face a plurality of one second surfaces 10b that are substantially flush with each other among the plurality of graphite blocks 10. In other words, in the heat transfer member 1 according to the embodiment, a plurality of graphite blocks 10 may be arranged side by side on one main surface 21A1 of the plate member 21A.

[0046] This can reduce the application of force in the direction of splitting the graphite block 10, thus enabling the high toughness of the heat transfer member 1 to be realized. The plate member 21A may be joined to a plurality of one of the second surfaces 10b by the joining material 30, thereby being physically and thermally connected to the plurality of graphite blocks 10.

[0047] Also, in the embodiment, the plate member 21A and the plate member 21B may be positioned so as to sandwich the plurality of graphite blocks 10.

[0048] That is, the main surface 21B1 of the plate member 21B may be positioned to face a plurality of the other second surfaces 10b that are substantially flush with each other among the plurality of graphite blocks 10. In other words, in the heat transfer member 1 according to the embodiment, the plurality of graphite blocks 10 may be arranged side by side on one main surface 21B1 of the plate member 21B.

[0049] This can reduce the application of force in the direction of splitting the graphite block 10, thus enabling the high toughness of the heat transfer member 1 to be realized. The plate member 21B may be joined to the plurality of the other second surfaces 10b by the joining material 30, thereby being physically and thermally connected to the plurality of graphite blocks 10.

[0050] Also, in the heat transfer member 1 according to the embodiment, both the plate member 21A and the plate member 21B may be joined to the crystal plane of the plurality of graphite blocks 10. That is, in the embodiment, any one of the plurality of surfaces extending along the first direction A1 in the graphite block 10 may be positioned to face the main surface 21A1 of the plate member 21A or the main surface 21B1 of the plate member 21B.

[0051] This can reduce the application of force in the direction of splitting the graphite block 10, thus enabling the high toughness of the heat transfer member 1 to be realized.

[0052] In addition, by joining the plate members 21A and 21B to a crystal layer surface having a surface roughness greater than that of the crystal plane, since the bonding material 30 is located in the recess F1 (see FIG. 3) of the crystal layer surface, the anchor effect acts, and the adhesiveness of the plate members 21A and 21B to the graphite block 10 can be improved.

[0053] Therefore, according to the embodiment, it is possible to reduce the peeling of the plate members 21A and 21B from the graphite block 10. Further, since the bonding material 30 is located in the recess F1 of the unevenness, the thermal resistance between the plate members 21A and 21B and the graphite block 10 can be reduced as compared with a configuration in which a gap is generated in the recess F1.

[0054] In the embodiment, the plate member 21A may have high isotropy in thermal conductivity as compared with the graphite block 10. Further, in the first direction A1, the thermal conductivity of the plate member 21A may be greater than the thermal conductivity of the graphite block 10.

[0055] Also, in a direction orthogonal to the first direction A1, for example, in the second direction A2 and the third direction A3, the thermal conductivity of the graphite block 10 may be greater than the thermal conductivity of the plate member 21A.

[0056] According to this configuration, when heat is applied to a part of the plate member 21A from the outside of the heat transfer member 1, after this heat is isotropically dispersed in the plate member 21A, it is transmitted to the graphite block 10. Then, in the graphite block 10, this heat is quickly dispersed in the second direction A2 and the third direction A3 having high thermal conductivity.

[0057] In this way, in the heat transfer member 1 according to the embodiment, even when heat is applied to a part of the plate member 21A, the heat can be dispersed over a wide range of the graphite block 10. Therefore, according to the embodiment, high heat transfer performance of the heat transfer member 1 can be realized.

[0058] In addition, in the embodiment, the heat conductivity of the plate member 21B may have high isotropy as compared with the graphite block 10. Also, in the first direction A1, the heat conductivity of the plate member 21B may be greater than the heat conductivity of the graphite block 10.

[0059] Also, in the directions orthogonal to the first direction A1, for example, the second direction A2 and the third direction A3, the heat conductivity of the graphite block 10 may be greater than the heat conductivity of the plate member 21B.

[0060] With this configuration, when heat is applied from the outside of the heat transfer member 1 to a part of the plate member 21A and this heat is rapidly dispersed in the second direction A2 and the third direction A3 where the heat conductivity is high in the graphite block 10, this heat is conducted to the plate member 21B and is isotropically dispersed in the plate member 21B.

[0061] Furthermore, since a wide range of the plate member 21B is thermally connected to the support that supports the heat transfer member 1, heat can be released from a wide range of the plate member 21B. Therefore, according to the embodiment, high heat transfer performance of the heat transfer member 1 can be realized.

[0062] Materials having a heat conductivity of 20 W / m·K or more and less than 400 W / m·K may be used for the plate member 21A and the plate member 21B.

[0063] In addition, in the embodiment, the coefficient of thermal expansion of the plate member 21A may have high isotropy as compared with the graphite block 10. Also, in the first direction A1, the coefficient of thermal expansion of the graphite block 10 may be greater than the coefficient of thermal expansion of the plate member 21A.

[0064] Also, in the directions orthogonal to the first direction A1, for example, the second direction A2 and the third direction A3, the coefficient of thermal expansion of the plate member 21A may be greater than the coefficient of thermal expansion of the graphite block 10.

[0065] With this configuration, compared to the configuration of the graphite block 10 alone, the coefficient of thermal expansion of one of the second surfaces 1b of the heat transfer member 1 can be made closer to an isotropic value. Therefore, according to the embodiment, when mounting components on one of the second surfaces 1b of the heat transfer member 1, the reliability of the mounting can be improved.

[0066] Note that the heat transfer member 1 may have a rectangular parallelepiped shape and may have a pair of first surfaces 1a, a pair of second surfaces 1b, and a pair of third surfaces 1c. The first surface 1a may be a surface that intersects, for example, is orthogonal to the first direction A1 in the heat transfer member 1, or may be a surface corresponding to the first surface 10a of the graphite block 10.

[0067] The second surface 1b may be a surface that extends along the first direction A1 in the heat transfer member 1, or may be a surface corresponding to the plate member 21A or the plate member 21B. The third surface 1c may be a surface that intersects the second surface 1b and extends along the first direction A1 and has a smaller area than the second surface 1b, or may be a surface corresponding to the third surface 10c of the graphite block 10.

[0068] Also, in the embodiment, the plate member 21B may have high isotropy in the coefficient of thermal expansion compared to the graphite block 10. Also, in the first direction A1, the coefficient of thermal expansion of the graphite block 10 may be larger than the coefficient of thermal expansion of the plate member 21B.

[0069] Also, in a direction orthogonal to the first direction A1, for example, in the second direction A2 and the third direction A3, the coefficient of thermal expansion of the plate member 21B may be larger than the coefficient of thermal expansion of the graphite block 10.

[0070] With this configuration, compared to the configuration of the graphite block 10 alone, the coefficient of thermal expansion of the other second surface 1b of the heat transfer member 1 can be made closer to an isotropic value. Therefore, according to the embodiment, when mounting the other second surface 1b of the heat transfer member 1 on a support, the reliability of the mounting can be improved.

[0071] Further, in the heat transfer member 1 according to the embodiment, the plurality of graphite blocks 10 may be arranged in a row along the first direction A1. Thereby, it is possible to reduce the inhibition of heat conduction in the direction intersecting the first direction A1 of the heat transfer member 1 by the bonding material 30 or the gap between the adjacent graphite blocks 10.

[0072] Furthermore, when the plurality of graphite blocks 10 are arranged in a row along the first direction A1, when the plurality of graphite blocks 10 thermally expand along the first direction A1, the bonding material 30 or the gap between the adjacent graphite blocks 10 allows the deformation due to this thermal expansion to escape.

[0073] The coefficient of thermal expansion of the plate materials 21A and 21B may be, for example, 4.0×10 -6 / K or more and less than 20×10 -6 / K, and may further be 6.0×10 -6 / K or more and less than 18×10 -6 / K.

[0074] For the plate materials 21A and 21B, a material having a coefficient of thermal expansion 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 may be used.

[0075] The main components of the plate materials 21A and 21B may be a copper-based metal or alloy such as oxygen-free copper. With this configuration, the anisotropy of the coefficient of thermal expansion on the second surface 1b can be reduced. Furthermore, since high thermal conductivity can be obtained in the plate materials 21A and 21B, higher heat transfer performance of the heat transfer member 1 can be realized.

[0076] The main components of the plate members 21A and 21B may be metals with high thermal conductivity such as aluminum. Even with this configuration, anisotropy of the coefficient of thermal expansion can be reduced as in the case of copper. Furthermore, since high thermal conductivity can be obtained in the plate members 21A and 21B, higher heat transfer performance of the heat transfer member 1 can be realized.

[0077] The main components of the plate members 21A and 21B may be ceramics such as alumina, silicon nitride, or aluminum nitride. Even with this configuration, anisotropy of the coefficient of thermal expansion can be reduced as in the case of copper. Furthermore, by forming the plate members 21A and 21B of ceramics, when insulation is required for the heat transfer member 1, this requirement can be met.

[0078] The main components of the plate members 21A and 21B may be alumina or silicon nitride. By using these materials, high rigidity against the residual stress of the graphite block 10 can be obtained.

[0079] Furthermore, the main component of the plate members 21A and 21B may be silicon nitride. By using this material, high thermal conductivity characteristics can be imparted to the plate members 21A and 21B in addition to rigidity, and higher thermal performance of the heat transfer member 1 can be realized.

[0080] Also, for example, when the coefficient of thermal expansion of the graphite block 10 is 24×10 -6 / K or more in the first direction A1, a metal material having a coefficient of thermal expansion larger than that of copper such as aluminum may be used for the plate members 21A and 21B.

[0081] In the present disclosure, the comparison between the coefficients of thermal expansion of the plate members 21A and 21B and the coefficient of thermal expansion of the graphite block 10 may be made using the coefficients of thermal expansion measured with a temperature change from 20°C to 100°C.

[0082] In addition, in the present disclosure, for the measurement of the coefficient of thermal expansion, a measurement method specified in JIS according to the material may be used. For example, when the plate materials 21A and 21B are metal materials, the measurement method specified in JIS_Z_2285:2003 may be used. Further, when the plate materials 21A and 21B are ceramic materials, the measurement method specified in JIS_R_1618:2002 may be used.

[0083] The hardness of the plate materials 21A and 21B may be higher than the hardness of the graphite block 10. With this configuration, even when an external force is applied to the plate materials 21A and 21B, this external force is dispersed and acts on the graphite block 10. Therefore, it is possible to reduce the breakage of the graphite block 10 inside the plate materials 21A and 21B.

[0084] In the present disclosure, Vickers hardness may be used as the hardness. Further, in the present disclosure, the Vickers hardness may be shown as a value obtained by converting the unit HV into pressure.

[0085] The hardness of the graphite block 10 may be 10 MPa or more and 40 MPa or less in terms of Vickers hardness. The hardness of the plate materials 21A and 21B may preferably be 10 times or more, more preferably 20 times or more, the hardness of the graphite block 10.

[0086] Further, the hardness of the plate materials 21A and 21B may preferably be 200 MPa or more in terms of Vickers hardness, more preferably 500 MPa in terms of Vickers hardness, and even more preferably 900 MPa or more in terms of Vickers hardness.

[0087] The Vickers hardness of the plate materials 21A and 21B can be measured using the measurement method specified in JIS_Z_2244:2009. Further, the Vickers hardness of the graphite block 10 may be a value converted from the measurement result using a nanoindentation test with a load of 20 mN / 10 seconds.

[0088] Materials having a hardness of 10 times or more the hardness of the graphite block 10 are, for example, various metallic materials such as copper, aluminum, or stainless steel, or ceramic materials such as aluminum nitride, alumina, or zirconia.

[0089] In addition, in the present disclosure, materials having a hardness of 10 times or more the hardness of the graphite block 10 are not limited to metallic materials or ceramic materials, and may be various materials such as resin materials.

[0090] The thicknesses of the plate members 21A and 21B may be 0.1 mm or more. By the thicknesses of the plate members 21A and 21B being 0.1 mm or more, deterioration due to the influence of corrosion by the reducing action of components contained in the joining material 30, such as Sn, can be withstood.

[0091] Also, the thickness of the plate member 21A and the thickness of the plate member 21B may be substantially equal. Thereby, since the coefficient of thermal expansion of the pair of second surfaces 1b in the heat transfer member 1 can be made closer to an isotropic value, the occurrence of warping due to temperature change can be reduced. Therefore, according to the embodiment, the reliability of mounting can be improved.

[0092] As the joining material 30 for joining the plate members 21A and 21B, which have been described so far, to the plurality of graphite blocks 10 respectively, a brazing material or solder may be used.

[0093] The joining material 30 may be configured as a clad that is coated on the joining surface of the plate member 21A or the plate member 21B at the manufacturing stage of the heat transfer member 1. According to this configuration, the thickness of the joining material 30 after joining can be reduced. Therefore, according to the embodiment, the thermal resistance in the joining material 30 can be reduced.

[0094] The bonding material 30 may be formed in a sheet shape at the manufacturing stage of the heat transfer member 1. In this case, the sheet-shaped bonding material 30 may be sandwiched between the plate material 21A or the plate material 21B and the graphite block 10, and then may be configured to exert a brazing action through a heating process and a cooling process.

[0095] According to this configuration, even if the second surface 10b of the graphite block 10 has a large area, the adhesiveness between the plate material 21A or the plate material 21B and the graphite block 10 via the bonding material 30 can be improved.

[0096] And by improving the adhesiveness between the plate material 21A or the plate material 21B and the graphite block 10, the thermal resistance between the plate material 21A or the plate material 21B and the graphite block 10 can be reduced as compared with a configuration in which a gap is interposed.

[0097] The bonding material 30 may be located only in a partial region of the second surface 10b of the graphite block 10. A gap may be formed in a range other than the region where the bonding material 30 is located.

[0098] Further, as shown in FIG. 6, the bonding material 30 may also be located in a partial region of the gap between adjacent graphite blocks 10. Thereby, a plurality of graphite blocks 10 joined to the plate materials 21A and 21B can be supported more strongly.

[0099] Further, in the embodiment, the bonding material 30 may contain a metal element capable of forming a carbide. Thereby, the adhesiveness between the graphite block 10 and the bonding material 30 can be improved.

[0100] In the present disclosure, the metal element capable of forming a carbide may be, for example, Cr (chromium), V (vanadium), Mo (molybdenum), Ti (titanium), Nb (niobium), W (tungsten), or Zr (zirconium).

[0101] Note that the definition of "carbide" in the present disclosure refers to a compound of carbon and an element more electropositive than carbon. For example, the most typical carbide in steel materials is Fe3C (cementite), but when it comes to alloy steel, carbides other than cementite are formed.

[0102] Each of the above-described metal elements forms its own carbide in steel, so these are referred to as carbide-forming elements in steel. When multiple types of alloying elements are added simultaneously, various elements are dissolved in the carbide.

[0103] For example, Cr or Mn (manganese) is dissolved in Fe3C, and in high-speed steel, (Fe, W, Cr, V)6C is formed. These may be referred to as M3C carbide and M6C carbide. Note that Si, Al, Ni, etc. also form carbides, but these carbides are not formed in steel, so they are called non-carbide-forming elements.

[0104] FIG. 7 is a diagram for explaining the configuration near the interface between the graphite block 10 and the joining material 30 according to the embodiment. As shown in FIG. 7, in the embodiment, a diffusion layer 31 may be located at the interface between the graphite block 10 and the joining material 30.

[0105] And in this diffusion layer 31, metal elements capable of forming carbides contained in the joining material 30 may diffuse. Thereby, the adhesiveness between the graphite block 10 and the joining material 30 can be further improved.

[0106] Also, in the embodiment, the diffusion layer 31 may be located only on the graphite block 10 side of the interface between the graphite block 10 and the joining material 30. Thereby, the adhesiveness between the graphite block 10 and the joining material 30 can be further improved.

[0107] In addition, in the embodiments described so far, the protective structure 20 that protects the plurality of graphite blocks 10 is not limited to the plate members 21A and 21B. For example, the protective structure 20 may include a protective layer in addition to the plate members 21A and 21B. Such a protective layer may be a plating layer or a resin layer.

[0108] By using a plating layer as the protective layer of the protective structure 20, a protective layer having high thermal conductivity can be realized, which can contribute to the high heat transfer performance of the heat transfer member 1. Furthermore, when electrical conductivity is required for the heat transfer member 1, it can meet this requirement.

[0109] The protective layer of the protective structure 20 may be located, for example, at least partially on a pair of first surfaces 1a of the heat transfer member 1 or at least partially on a pair of third surfaces 1c. On the first surface 1a of the heat transfer member 1, the first surface 10a of the graphite block 10 is located.

[0110] And as shown in FIG. 2, the first surface 10a is a crystal plane where graphene 11 is likely to peel off, and the edge portion E1 of graphene 11 that is likely to be damaged may appear. Therefore, by positioning the protective layer of the protective structure 20 on the first surface 1a of the heat transfer member 1, the occurrence of peeling or breakage of graphene 11 can be reduced, and high toughness of the heat transfer member 1 can be realized.

[0111] In addition, the protective layer of the protective structure 20 may be located on the side surface of the plate member 21A or the side surface of the plate member 21B in addition to the exposed surfaces of the plurality of graphite blocks 10 exposed from the plate members 21A and 21B.

[0112] The side surfaces of the plate member 21A and the side surface of the plate member 21B are more likely to adhere to the protective layer with higher strength than the exposed surfaces of the graphite blocks 10. Therefore, by positioning the protective layer on the side surface of the plate member 21A or the side surface of the plate member 21B, peeling of the protective layer can be reduced.

[0113] Further, the protective layer of the protection structure 20 may be located at least in part on the surface of the plate member 21A opposite to the main surface 21A1, or may be located at least in part on the surface of the plate member 21B opposite to the main surface 21B1. Also with this configuration, peeling of the protective layer can be reduced.

[0114] Further, the protective layer of the protection structure 20 may be located on all of the exposed surfaces of the plurality of graphite blocks 10, all of the side surfaces of the plate member 21A, all of the side surfaces of the plate member 21B, all of the surfaces of the plate member 21A opposite to the main surface 21A1, and all of the surfaces of the plate member 21B opposite to the main surface 21B1. That is, the protective layer of the protection structure 20 may collectively cover the structure composed of the plurality of graphite blocks 10, the plate member 21A, the plate member 21B, and the bonding material 30.

[0115] With this configuration, for example, the edges of the protective layer are reduced or eliminated, so that peeling and breakage of the protective layer can be further reduced. Further, with this configuration, the complexity of the process of forming the protective layer can be reduced.

[0116] When the protective layer of the protection structure 20 is located at least in part on the surface of the plate member 21A opposite to the main surface 21A1 or at least in part on the surface of the plate member 21B opposite to the main surface 21B1, a material with high thermal conductivity such as a metal plating layer may be used for the protective layer.

[0117] With this configuration, when a heat source contacts the protective layer of the heat transfer member 1, heat can be quickly conducted to the plate member 21A or the plate member 21B through such a protective layer.

[0118] The thermal conductivity of the protective layer of the protection structure 20 may have high isotropy as compared with the graphite block 10. The thermal conductivity of the protective layer may be higher than the thermal conductivity of the graphite block 10 in the first direction A1.

[0119] With this configuration, the effect of dispersing heat in the first direction A1 through the protective layer on the third surface 1c can be obtained. Therefore, by adding this dispersing effect, higher heat transfer performance of the heat transfer member 1 can be realized.

[0120] <Electronic device> FIG. 8 is a side view showing an example of the configuration of the electronic device 100 according to the embodiment. As shown in FIG. 8, the electronic device 100 may include a heat transfer member 1, an electronic element 101, and a module substrate 102. The electronic element 101 is an example of a heat source, and the module substrate 102 is an example of a support.

[0121] The electronic element 101 may be mounted on one second surface 1b of the heat transfer member 1 via a bonding material 103 such as solder. That is, the electronic element 101 may be thermally connected to the heat transfer member 1 via the bonding material 103. With this configuration, the heat of the electronic element 101 can be quickly conducted from one second surface 1b to the other second surface 1b of the heat transfer member 1.

[0122] The other second surface 1b of the heat transfer member 1 may be supported by the module substrate 102 via a bonding material 104 such as solder. And the other second surface 1b of the heat transfer member 1 may be thermally connected to a heat sink (not shown) via the module substrate 102.

[0123] With this configuration, the heat of the electronic element 101 can be quickly conducted to the module substrate 102 and the heat sink through the heat transfer member 1 and released from the heat sink.

[0124] Also, in the embodiment, in the first direction A1, the coefficient of thermal expansion of the graphite block 10 (see FIG. 6) may be larger than the coefficient of thermal expansion of the module substrate 102.

[0125] In the embodiment, by having the plate material 21B positioned between the plurality of graphite blocks 10 and the module substrate 102, the difference in the coefficient of thermal expansion between the graphite block 10 and the module substrate 102 can be reduced. Therefore, according to this configuration, high toughness of the electronic device 100 can be realized.

[0126] FIG. 9 is a side view showing another example of the configuration of the electronic device 100 according to the embodiment. As shown in FIG. 9, the electronic device 100 may include a heat transfer member 1, an electronic element 101, and a heat sink 110. The heat sink 110 is another example of a support.

[0127] The electronic element 101 may be mounted on one second surface 1b of the heat transfer member 1 via a bonding material 103 such as solder. That is, the electronic element 101 may be thermally connected to the heat transfer member 1 via the bonding material 103. With this configuration, the heat of the electronic element 101 can be quickly conducted from one second surface 1b to the other second surface 1b of the heat transfer member 1.

[0128] The other second surface 1b of the heat transfer member 1 may be supported by the heat sink 110 via a bonding material 111 such as solder. That is, the other second surface 1b of the heat transfer member 1 may be thermally connected to the heat sink 110.

[0129] With this configuration, the heat of the electronic element 101 can be quickly conducted to the heat sink 110 via the heat transfer member 1 and released from the heat sink 110.

[0130] Further, in the embodiment, in the first direction A1, the coefficient of thermal expansion of the graphite block 10 (see FIG. 6) may be larger than the coefficient of thermal expansion of the heat sink 110.

[0131] In the embodiment, by positioning the plate member 21B between the plurality of graphite blocks 10 and the heat sink 110, the difference in the coefficient of thermal expansion between the graphite block 10 and the heat sink 110 can be reduced. Therefore, according to this configuration, high toughness of the electronic device 100 can be realized.

[0132] Note that in the present disclosure, the heat source that is thermally connected to the heat transfer member 1 is not limited to the electronic element 101. For example, various objects such as a heat pipe for exhaust heat or a heater for heating can be applied as the heat source.

[0133] Also, in the present disclosure, the support that supports the heat transfer member 1 is not limited to the module substrate 102 or the heat sink 110. For example, when a heater is applied as the heat source, an object to be heated may be arranged as the support on the second surface 1b opposite to the second surface 1b where the heat source is located in the heat transfer member 1. With this configuration, the heat variation in each part of the heater can be equalized, and heat can be transferred to the object to be heated.

[0134] <Another Embodiment> Next, the configuration of the heat transfer member 1 according to another various embodiments will be described with reference to FIGS. 10 to 13. FIG. 10 is a cross-sectional view showing an example of the configuration of the heat transfer member 1 according to another embodiment 1.

[0135] As shown in FIG. 10, in another embodiment 1, the position of the bonding material 30 is different from that in the above-described embodiment. Specifically, in another embodiment 1, the bonding material 30 may be located in all regions in the gap between the graphite blocks 10 adjacent to each other.

[0136] Thereby, the plurality of graphite blocks 10 joined to the plate member 21A and the plate member 21B can be supported more firmly.

[0137] FIG. 11 is a perspective view showing an example of the configuration of the heat transfer member 1 according to another embodiment 2. FIG. 12 is a cross-sectional view taken along the line B-B shown in FIG. 11. As shown in FIGS. 11 and 12, in another embodiment 2, the configuration of the protection structure 20 is different from that of the above-described embodiment. Specifically, in another embodiment 2, the protection structure 20 may have a plate material 21A.

[0138] The main surface 21A1 of the plate material 21A may be positioned to face a plurality of one second surfaces 10b that are substantially flush in the plurality of graphite blocks 10. In other words, in the heat transfer member 1 according to another embodiment 2, the plurality of graphite blocks 10 may be arranged side by side on one main surface 21A1 of the plate material 21A.

[0139] Thereby, since the force in the direction of splitting the graphite block 10 can be reduced, high toughness of the heat transfer member 1 can be realized. The plate material 21A may be joined to a plurality of one second surfaces 10b by a joining material 30, thereby being physically and thermally connected to the plurality of graphite blocks 10.

[0140] Further, in the heat transfer member 1 according to another embodiment 2, the plate material 21A may be joined to the crystal plane of the plurality of graphite blocks 10. That is, in another embodiment 2, any one of the plurality of surfaces extending along the first direction A1 in the graphite block 10 and the main surface 21A1 of the plate material 21A may be positioned to face each other.

[0141] Thereby, since the force in the direction of splitting the graphite block 10 can be reduced, high toughness of the heat transfer member 1 can be realized.

[0142] Further, since the plate material 21A is joined to the crystal plane having a larger surface roughness than the crystal plane, the joining material 30 is located in the recess F1 (see FIG. 3) of the crystal plane, so that the anchor effect works and the adhesiveness of the plate material 21A to the crystal plane can be improved.

[0143] Therefore, according to another Embodiment 2, it is possible to reduce the peeling of the plate member 21A from the graphite block 10. Further, since the bonding material 30 is located in the concave portion F1 of the unevenness, it is possible to reduce the thermal resistance between the plate member 21A and the graphite block 10 as compared with a configuration in which a gap is generated in the concave portion F1.

[0144] Further, in another Embodiment 2, the plate member 21A may have high isotropy in thermal conductivity as compared with the graphite block 10. Also, in the first direction A1, the thermal conductivity of the plate member 21A may be greater than the thermal conductivity of the graphite block 10.

[0145] Also, in the directions orthogonal to the first direction A1, for example, the second direction A2 and the third direction A3, the thermal conductivity of the graphite block 10 may be greater than the thermal conductivity of the plate member 21A.

[0146] According to this configuration, when heat is applied to a part of the plate member 21A from the outside of the heat transfer member 1, this heat is isotropically dispersed in the plate member 21A and then transmitted to the graphite block 10. Then, in the graphite block 10, this heat is quickly dispersed in the second direction A2 and the third direction A3 with high thermal conductivity.

[0147] Thus, in the heat transfer member 1 according to another Embodiment 2, even when heat is applied to a part of the plate member 21A, the heat can be dispersed over a wide range of the graphite block 10. Therefore, according to another Embodiment 2, high heat transfer performance of the heat transfer member 1 can be realized.

[0148] Further, in another Embodiment 2, the plate member 21A may have high isotropy in the coefficient of thermal expansion as compared with the graphite block 10. Also, in the first direction A1, the coefficient of thermal expansion of the graphite block 10 may be greater than the coefficient of thermal expansion of the plate member 21A.

[0149] Further, in the directions orthogonal to the first direction A1, for example, the second direction A2 and the third direction A3, the coefficient of thermal expansion of the plate member 21A may be greater than the coefficient of thermal expansion of the graphite block 10.

[0150] Thereby, compared with the configuration of the graphite block 10 alone, the coefficient of thermal expansion of one second surface 1b of the heat transfer member 1 can be made closer to an isotropic value. Therefore, according to the embodiment, when mounting components on one second surface 1b of the heat transfer member 1, the reliability of the mounting can be improved.

[0151] Further, in another embodiment 2, the bonding material 30 may be located in a partial region in the gap between the adjacent graphite blocks 10. Thereby, the plurality of graphite blocks 10 bonded to the plate member 21A can be supported more firmly.

[0152] Note that, in another embodiment 2, the protection structure 20 for protecting the plurality of graphite blocks 10 is not limited to the plate member 21A. For example, the protection structure 20 may include a protective layer in addition to the plate member 21A. Such a protective layer may be a plating layer or a resin layer.

[0153] By using a plating layer as the protective layer of the protection structure 20, a protective layer having high thermal conductivity can be realized, which can contribute to the high heat transfer performance of the heat transfer member 1. Further, when electrical conductivity is required for the heat transfer member 1, this requirement can be met.

[0154] The protective layer of the protection structure 20 may be located at least in part on the second surface 1b of the heat transfer member 1 opposite to the second surface 1b where the plate member 21A is located.

[0155] Further, the protective layer of the protection structure 20 may be located at least in part on one pair of first surfaces 1a and one pair of third surfaces 1c of the heat transfer member 1. By the protective layer of the protection structure 20 being located on the first surface 1a of the heat transfer member 1, the occurrence of peeling or breakage of the graphene 11 can be reduced, and high toughness of the heat transfer member 1 can be realized.

[0156] Further, the protective layer of the protection structure 20 may be located on the side surface of the plate member 21A in addition to the exposed surfaces of the plurality of graphite blocks 10 exposed from the plate member 21A. The side surface of the plate member 21A is easier to adhere to the protective layer with higher strength than the exposed surface of the graphite block 10. Therefore, by positioning the protective layer on the side surface of the plate member 21A, peeling of the protective layer can be reduced.

[0157] Further, the protective layer of the protection structure 20 may be located on at least a part of the surface opposite to the main surface 21A1 of the plate member 21A. Also with this configuration, peeling of the protective layer can be reduced.

[0158] Further, the protective layer of the protection structure 20 may be located on all of the exposed surfaces of the plurality of graphite blocks 10, all of the side surfaces of the plate member 21A, and all of the surfaces opposite to the main surface 21A1 of the plate member 21A. That is, the protective layer of the protection structure 20 may collectively cover the structure composed of the plurality of graphite blocks 10, the plate member 21A, and the bonding material 30.

[0159] With this configuration, for example, the edges of the protective layer are reduced or eliminated, so that peeling and breakage of the protective layer can be further reduced. Furthermore, with this configuration, the complexity of the process of forming the protective layer can be reduced.

[0160] When the protective layer of the protection structure 20 is located on at least a part of the surface opposite to the main surface 21A1 of the plate member 21A, a material with high thermal conductivity such as a metal plating layer may be used for the protective layer. With this configuration, even when a heat source is in contact with the heat transfer member 1 through the protective layer, heat can be quickly conducted to the plate member 21A through the protective layer.

[0161] FIG. 13 is a cross-sectional view showing an example of the configuration of the heat transfer member 1 according to another embodiment 3. As shown in FIG. 13, in another embodiment 3, the position of the bonding material 30 is different from that in the above-described another embodiment 2. Specifically, in another embodiment 3, the bonding material 30 may be located in all regions in the gaps between adjacent graphite blocks 10.

[0162] As a result, a plurality of graphite blocks 10 joined to the plate material 21A can be supported more firmly.

[0163] Next, the configuration of the heat transfer member 1 according to another embodiment 4 will be described with reference to FIGS. 14 to 16. In another embodiment 4, the heat transfer member 1 may have a graphite base 200 which is a structure including a plurality of graphite blocks 10. FIG. 14 is a perspective view showing an example of the configuration of the graphite base 200 according to another embodiment 4.

[0164] As shown in FIG. 14, the graphite base 200 may be, for example, a structure including a plurality of graphite blocks 10 arranged along a first direction A1. In the example shown in FIG. 14, the graphite base 200 has three graphite blocks 10. The adjacent graphite blocks 10 along the first direction A1 may be joined by a joining material 210.

[0165] The joining material 210 may be a brazing material or solder. The joining material 210 may contain a metal element capable of forming a carbide. That is, the joining material 210 may be the same joining material as the above-described joining material 30.

[0166] The graphite base 200 may have a first surface 201 and a second surface 202 located opposite to the first surface 201. In FIG. 14, the first surface 201 is a surface including one second surface 10b of a plurality of graphite blocks 10 located substantially in a plane, and the second surface 202 may be a surface including the other second surface 10b of a plurality of graphite blocks 10 located substantially in a plane.

[0167] In the graphite base 200, the direction of the plurality of graphite blocks 10 in the first direction A1 may be parallel to the first surface 201, and the direction of the plurality of graphite blocks 10 in the third direction A3 may be orthogonal to the first surface 201.

[0168] The thickness of the graphite block 10 in the direction orthogonal to the first surface 201, that is, along the third direction A3, may be, for example, 0.5 mm or more. Or, for example, it may be 0.5 mm or more. According to such a configuration, the toughness of the graphite block 10 can be enhanced.

[0169] The thickness of the graphite block 10 along the third direction A3 may be, for example, 15 mm or less. Or, for example, it may be 10 mm or less.

[0170] FIG. 15 is a perspective view showing an example of the configuration of the heat transfer member 1 according to another embodiment 4. FIG. 16 is a cross-sectional view taken along the arrow of the C-C line shown in FIG. 15. As shown in FIGS. 15 and 16, in another embodiment 4, the heat transfer member 1 may have a protective structure 20 that protects the graphite substrate 200. Specifically, the heat transfer member 1 may have a plate member 21A located on the first surface 201 and a plate member 21B located on the second surface 202.

[0171] The plate member 21A and the plate member 21B in another embodiment 4 may be made of, for example, ceramics. Specifically, the plate member 21A and the plate member 21B may be, for example, silicon nitride. Or, the plate member 21A and the plate member 21B may be, for example, aluminum nitride or alumina. Hereinafter, such a plate member 21A is also referred to as the first insulating substrate 21A, and such a plate member 21B is also referred to as the second insulating substrate 21B.

[0172] The thickness of the first insulating substrate 21A and the second insulating substrate 21B may be, for example, 0.1 mm or more. More preferably, for example, it may be 0.2 mm or more. According to such a configuration, the insulation property of the heat transfer member 1 can be enhanced.

[0173] The thickness of the first insulating substrate 21A and the second insulating substrate 21B may be, for example, 0.4 mm or less. According to such a configuration, the thermal conductivity of the heat transfer member 1 can be enhanced.

[0174] The main surface 21A1 of the first insulating substrate 21A may be joined to the first surface 201 of the graphite substrate 200 by a joining material 60. Also, the main surface 21B1 of the second insulating substrate 21B may be joined to the second surface 202 of the graphite substrate 200 by the joining material 60. Thereby, the first insulating substrate 21A and the second insulating substrate 21B may be physically and thermally connected to the graphite substrate 200.

[0175] The joining material 60 may be a brazing material or solder. The joining material 60 may contain a metal element capable of forming a carbide. That is, the joining material 60 may be the same joining material as the above-described joining material 30 and the above-described joining material 210.

[0176] The surface roughness of the first insulating substrate 21A and the second insulating substrate 21B may be, for example, 0.03 μm or more. More preferably, it may be, for example, 0.05 μm or more. According to such a configuration, when the first insulating substrate 21A and the second insulating substrate 21B are joined to the graphite substrate 200 by the joining material 60, they can be joined more firmly by the anchor effect.

[0177] The surface roughness of the first insulating substrate 21A and the second insulating substrate 21B may be, for example, 1.0 μm or less. More preferably, it may be, for example, 0.8 μm or less. According to such a configuration, since a gap is less likely to occur between the first insulating substrate 21A and the second insulating substrate 21B and the joining material 60, the thermal conductivity of the heat transfer member 1 can be increased.

[0178] The heat transfer member 1 may have a first metal electrode 40 located on the main surface 21A2 of the first insulating substrate 21A. The number of the first metal electrodes 40 may be plural. In another embodiment 4, the heat transfer member 1 may have four first metal electrodes 40. The first metal electrode 40 may be, for example, a thin plate having a quadrangular shape in plan view. Also, the first metal electrode 40 may be, for example, a copper electrode.

[0179] Note that the first metal electrode 40 has a higher thermal conductivity than the first insulating substrate 21A. That is, the first metal electrode 40 is superior in in-plane heat uniformity to the first insulating substrate 21A.

[0180] The first metal electrode 40 may be joined to the main surface 21A2 by a joining material such as a brazing material or solder (not shown). With this configuration, the first metal electrode 40 may be physically and thermally connected to the first insulating substrate 21A. Such a joining material may be the same joining material as the above-described joining materials 30, 60, and 210.

[0181] According to the heat transfer member 1 having the first metal electrode 40, for example, when heat is applied from the outside on the first surface 201 side of the heat transfer member 1, such heat is uniformly conducted in-plane to the first insulating substrate 21A via the first metal electrode 40. Thereby, heat can be dispersed over a wide range of the graphite substrate 200. Therefore, the heat transfer performance of the heat transfer member 1 can be enhanced.

[0182] Also, although not specifically described hereinafter, a semiconductor element 70 described hereinafter may be connected to the first metal electrode 40. According to the heat transfer member 1 having the first metal electrode 40, such a semiconductor element 70 can be simply connected to the heat transfer member 1.

[0183] The heat transfer member 1 may have a second metal electrode 50 located on the main surface 21B2 of the second insulating substrate 21B. The number of the second metal electrodes 50 may be plural. In another embodiment 4, the heat transfer member 1 may have four second metal electrodes 50. The second metal electrode 50 may be, for example, a thin plate having a quadrangular shape in plan view. The second metal electrode 50 may be, for example, a copper electrode.

[0184] Note that the second metal electrodes 50 may be respectively located at positions opposite to the first metal electrode 40. Also, the second metal electrode 50 has a higher thermal conductivity than the second insulating substrate 21B. That is, the second metal electrode 50 is superior in in-plane heat uniformity to the second insulating substrate 21B.

[0185] The second metal electrode 50 may be joined onto the main surface 21B2 by a joining material such as a brazing material or solder (not shown). With this configuration, the second metal electrode 50 may be physically and thermally connected to the second insulating substrate 21B. Such a joining material may be the same joining material as the above-described joining materials 30, 60, and 210.

[0186] According to the heat transfer member 1 having the second metal electrode 50, for example, heat conducted from the outside on the first surface 201 side of the heat transfer member 1 through the graphite substrate 200 and the second insulating substrate 21B can be uniformly dispersed in the in-plane direction at the second metal electrode 50. Thereby, heat can be effectively radiated through the second metal electrode 50. Therefore, the heat dissipation performance of the heat transfer member 1 can be enhanced.

[0187] Also, although not specifically described hereinafter, a cooling member 80 (to be described later) may be connected to the second metal electrode 50. According to the heat transfer member 1 having the second metal electrode 50, such a cooling member 80 can be easily connected to the heat transfer member 1.

[0188] Note that, although the example in the case where the second metal electrode 50 is located on the second insulating substrate 21B has been described so far, the present invention is not limited thereto, and the second metal electrode 50 may be directly located on the second surface 202 of the graphite substrate 200. That is, the heat transfer member 1 may have a configuration without the second insulating substrate 21B.

[0189] In such a case, the second metal electrode 50 may be joined to the second surface 202 by a joining material such as a brazing material or solder (not shown). Such a joining material may contain a metal element capable of forming a carbide.

[0190] Also, in such a case, the portion of the graphite block 10 exposed in the graphite substrate 200 may be coated with, for example, a metal plating. Specifically, the second surface 202 and the surface of the graphite substrate 200 located between the first surface 201 and the second surface 202 may be coated with a metal plating or the like. Thereby, the diffusion of the fragments of the graphite block 10 can be reduced.

[0191] Further, in such a case, when the second metal electrode 50 is located on the second surface 202, the deformation due to the thermal stress of the heat transfer member 1 is reduced. For example, when only the first surface 201 is fixed by the first insulating substrate 21A, the graphite substrate 200 is likely to warp. If the second metal electrode 50 is located on the second surface 202, the concentration of the thermal stress in the graphite substrate 200 is alleviated, so that the occurrence of warping is reduced.

[0192] Next, the configuration of the electronic device 300 according to another embodiment 4 will be described with reference to FIGS. 17 and 18. FIG. 17 is a perspective view showing an example of the configuration of the electronic device 300 according to another embodiment 4. FIG. 18 is a cross-sectional view taken along the line D-D shown in FIG. 17. As shown in FIGS. 17 and 18, the electronic device 300 may include a heat transfer member 1, a semiconductor element 70, and a cooling member 80.

[0193] As shown in FIG. 17, in the electronic device 300, the first metal electrode 40 of the heat transfer member 1 and the semiconductor element 70 may be thermally connected. The semiconductor element 70 may be, for example, a SiC element, a GaN element, or the like. The first metal electrode 40 and the semiconductor element 70 may be joined by a joining material (not shown) such as solder.

[0194] Also, as shown in FIG. 18, in the electronic device 300, the second metal electrode 50 of the heat transfer member 1 and the cooling member 80 may be thermally connected. The cooling member 80 may be, for example, a metal plate or the like through which a cooling medium such as water can flow inside. The second metal electrode 50 and the cooling member 80 may be joined by a joining material (not shown) such as solder.

[0195] According to the electronic device 300, by using the heat transfer member 1 according to another embodiment 4, the semiconductor element 70 can be quickly cooled. Specifically, the electronic device 300 may be mounted on, for example, a power device module or the like.

[0196] According to the electronic device 300, for example, by placing the semiconductor element 70 on the surface of the first metal electrode 40, the semiconductor element 70 can be cooled. Therefore, the semiconductor element 70 can be cooled with a simpler configuration compared to, for example, the case of directly cooling the semiconductor element 70.

[0197] In recent years, the practical application of SiC elements, GaN elements, etc. as semiconductor elements mounted on, for example, power device modules has been progressing. Such next-generation semiconductor elements can be miniaturized compared to conventional semiconductor elements such as Si elements, while the heat generation amount per unit volume is large. For this reason, improvement of cooling efficiency is required in next-generation semiconductor elements.

[0198] The electronic device 300 can effectively cool even such next-generation semiconductor elements, that is, semiconductor elements that require higher cooling performance than before.

[0199] Specifically, according to the electronic device 300, in a power device module or the like that mounts the above-mentioned next-generation semiconductor element, by effectively cooling the semiconductor element, the operating temperature of such a module can be kept, for example, at 175°C or lower. The 175°C mentioned here is, for example, the upper limit standard value of the operating temperature of a general electrical element including a semiconductor element. Therefore, by using the electronic device 300, it becomes possible to use general electrical elements in a power device module or the like.

[0200] Next, the configuration of the heat transfer member 1 according to another embodiment 5 will be described with reference to FIG. 19. FIG. 19 is a perspective view showing an example of the configuration of the heat transfer member 1 according to another embodiment 5. As shown in FIG. 19, the graphite substrate 200 in another embodiment 5 may be a laminate in which a plurality of graphite blocks 10 are laminated.

[0201] According to such a configuration, the thickness of the graphite substrate 200 along the direction orthogonal to the first surface 201 can be easily adjusted.

[0202] Specifically, as shown in FIG. 19, the graphite substrate 200 according to another embodiment 5 includes a first layer 203 including a plurality, for example, three graphite blocks 10 arranged along the first direction A1, and a plurality, for example, four graphite blocks 10 arranged along the first direction A1 And a third layer 205 including a plurality of, for example, three graphite blocks 10 arranged along the first direction A1.

[0203] In FIG. 19, the first direction A1 of the graphite blocks 10 in the first layer 203 and the third layer 205 is, for example, in the X-axis direction. Also, the first direction A1 of the graphite blocks 10 in the second layer 204 is, for example, in the Y-axis direction.

[0204] The graphite substrate 200 may be, for example, a laminate in which the first layer 203, the second layer 204, and the third layer 205 are laminated along the negative Z-axis direction. The adjacent graphite blocks 10 along the lamination direction (negative Z-axis direction) may be joined by a joining material 60. That is, the joining material 60 may be located between the first layer 203 and the second layer 204, and between the second layer 204 and the third layer 205.

[0205] In the graphite substrate 200 according to another Embodiment 5, the first surface 201 is a surface including a plurality of second surfaces 10b of the first layer 203, and the second surface 202 is a surface including a plurality of second surfaces 10b of the third layer 205. In the graphite substrate 200, the orientation of the plurality of graphite blocks 10 in the first direction A1 is parallel to the first surface 201.

[0206] As shown in FIG. 19, the orientations of the adjacent graphite blocks 10 along the stacking direction of the graphite substrate 200 may be shifted by 90° in the first direction A1. That is, the first layer 203 and the second layer 204 may be stacked in a state where the orientations in the first direction A1 are rotated 90° with respect to each other. Similarly, the second layer 204 and the third layer 205 may be stacked in a state where the orientations in the first direction A1 are rotated 90° with respect to each other.

[0207] According to such a configuration, when the graphite substrate 200 is a laminate of a plurality of graphite blocks 10, it is possible to reduce the anisotropy of heat conduction in the direction parallel to the stacking direction, that is, in the XY plane direction in FIG. 19.

[0208] Specifically, the graphite substrate 200 can preferably conduct heat along the Y-axis direction in the first layer 203 and the third layer 205, and can preferably conduct heat along the X-axis direction in the second layer 204. Thereby, the graphite substrate 200 can disperse heat isotropically as a whole.

[0209] As described above, the present disclosure has been described in detail. However, the present disclosure is not limited to the above-described embodiments, and various changes and improvements are possible without departing from the gist of the present disclosure.

[0210] It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. In fact, the above-described embodiments can be embodied in various forms. Also, the above embodiments may be omitted, replaced, or changed in various forms without departing from the scope and gist of the appended claims.

[0211] Note that the present technology can also be configured as follows. (A1) A plurality of graphite blocks having a structure in which a plurality of graphenes are laminated in a first direction, A protective structure for protecting the plurality of graphite blocks, comprising: The protective structure is physically and thermally connected to the plurality of graphite blocks, The graphite block has anisotropy in thermal conductivity and coefficient of thermal expansion, In the first direction, the thermal conductivity of the protective structure is greater than that of the graphite block, In a direction orthogonal to the first direction, the thermal conductivity of the graphite block is greater than that of the protective structure, In the first direction, the coefficient of thermal expansion of the graphite block is greater than that of the protective structure, In a direction orthogonal to the first direction, the coefficient of thermal expansion of the protective structure is greater than that of the graphite block, The protective structure has a single plate material, The plurality of graphite blocks are arranged side by side on one main surface of the plate material Heat transfer member. (A2) The plurality of graphite blocks are arranged in a row along the first direction The heat transfer member according to (A1). (A3) The graphite block has a rectangular parallelepiped shape and is positioned so that any one of a plurality of surfaces extending along the first direction faces one main surface of the plate material The heat transfer member according to (A1) or (A2). (A4) The protective structure has another plate material, The plate material and the other plate material are positioned so as to sandwich the plurality of graphite blocks The heat transfer member according to any one of (A1) to (A3). (A5) The plate material is joined to the graphite block by a joining material containing a metal element capable of forming a carbide. The heat transfer member according to any one of (A1) to (A4). (A6) The joining material is located between the adjacent graphite blocks. The heat transfer member according to (A5). (A7) The heat transfer member according to any one of (A1) to (A6), a heat source thermally connected to the heat transfer member, a support for supporting the heat transfer member, and in the first direction, the thermal expansion coefficient of the graphite block is greater than that of the support. An electronic device.

[0212] In addition, the present technology can also adopt the following configuration. (B1) A structure including a plurality of graphite blocks having a structure in which a plurality of graphites are laminated in a first direction, a graphite substrate having a first surface, a first insulating substrate that protects the graphite substrate on the first surface and is physically and thermally connected to the graphite substrate, a first metal electrode located on the first insulating substrate and physically and thermally connected to the first insulating substrate and a plurality of the graphite blocks are heat transfer members whose orientation in the first direction is parallel to the first surface. (B2) The graphite substrate has a second surface located opposite to the first surface, The heat transfer member according to (B1), further comprising a second metal electrode located on the second surface and physically and thermally connected to the graphite substrate. (B3) The graphite substrate has a second surface located opposite to the first surface, A second insulating substrate that is physically and thermally connected to the graphite substrate on the second surface; The heat transfer member according to (B1), further comprising a second metal electrode that is located on the second insulating substrate and is physically and thermally connected to the second insulating substrate. (B4) The heat transfer member according to any one of (B1) to (B3), wherein the graphite substrate is a laminate in which a plurality of the graphite blocks are laminated along a direction orthogonal to the first surface. (B5) The heat transfer member according to (B4), wherein the directions of the adjacent graphite blocks along the lamination direction of the laminate are shifted by 90°. (B6) The heat transfer member according to any one of (B1) to (B5), wherein the graphite substrate, the first insulating substrate, and the first insulating substrate and the first metal electrode are joined by a joining material containing a metal element. (B7) The heat transfer member according to (B4) or (B5), wherein the adjacent graphite blocks along the lamination direction of the laminate are joined by a joining material containing a metal element. (B8) The graphite block has anisotropy in thermal conductivity and thermal expansion coefficient, In the first direction, the thermal conductivity of the first insulating substrate is greater than the thermal conductivity of the graphite block, In a direction orthogonal to the first direction, the thermal conductivity of the graphite block is greater than the thermal conductivity of the first insulating substrate, In the first direction, the thermal expansion coefficient of the graphite block is greater than the thermal expansion coefficient of the first insulating substrate, In a direction orthogonal to the first direction, the thermal expansion coefficient of the first insulating substrate is greater than the thermal expansion coefficient of the graphite block. The heat transfer member according to any one of (B1) to (B7). (B9) The first metal electrode is the heat transfer member according to any one of (B1) to (B8), which is thermally connected to the semiconductor element. (B10) The second metal electrode is the heat transfer member according to any one of (B1) to (B9), which is thermally connected to the cooling member. (B11) The thickness of the graphite block along the direction perpendicular to the first surface is 0.5 mm or more and 15 mm or less, which is the heat transfer member according to any one of (B1) to (B10). (B12) The thickness of the first insulating substrate is 0.1 mm or more and 0.4 mm or less, which is the heat transfer member according to any one of (B1) to (B11). (B13) The surface roughness of the first insulating substrate is 0.03 μm or more and 1.0 μm or less, which is the heat transfer member according to any one of (B1) to (B12).

Explanation of Reference Signs

[0213] 1 Heat transfer member 1a First surface 1b Second surface 1c Third surface 10 Graphite block 10a First surface 10b Second surface 10c Third surface 20 Protection structure 21A Plate material, first insulating substrate 21A1 Main surface 21A2 Main surface 21B Plate material (an example of another plate material), second insulating substrate 21B1 Main surface 21B2 Main surface 30 Bonding material 31 Diffusion layer 40 First metal electrode 50 Second metal electrode 60 Bonding material 70 Semiconductor element 80 Cooling member 100 Electronic device 101 Electronic element (an example of a heat source) 102 Module Substrate (an example of a support) 110 Heat Sink (an example of a support) 200 Graphite Substrate 201 First Surface 202 Second Surface 210 Bonding Material 300 Electronic Device A1 First Direction A2 Second Direction A3 Third Direction

Claims

1. A plurality of graphite blocks each having a structure in which a plurality of graphenes are stacked in a first direction; A protective structure for protecting the plurality of graphite blocks; Comprising: The protective structure is physically and thermally connected to the plurality of graphite blocks; The graphite block has anisotropy in thermal conductivity and thermal expansion coefficient; In the first direction, the thermal conductivity of the protective structure is greater than the thermal conductivity of the graphite block; In a direction orthogonal to the first direction, the thermal conductivity of the graphite block is greater than the thermal conductivity of the protective structure; In the first direction, the thermal expansion coefficient of the graphite block is greater than the thermal expansion coefficient of the protective structure; In a direction orthogonal to the first direction, the thermal expansion coefficient of the protective structure is greater than the thermal expansion coefficient of the graphite block; The protective structure has one plate material; The plurality of graphite blocks are arranged side by side on one main surface of the plate material Heat transfer member.

2. The plurality of graphite blocks are arranged in a row along the first direction The heat transfer member according to claim 1.

3. The graphite block has a rectangular parallelepiped shape and is positioned such that any one of a plurality of surfaces extending along the first direction faces one main surface of the plate material The heat transfer member according to claim 1 or 2.

4. The protective structure has another plate material; The plate material and the another plate material are positioned so as to sandwich the plurality of graphite blocks The heat transfer member according to claim 1 or 2.

5. The plate material is joined to the graphite block by a bonding material containing a metal element capable of forming a carbide The heat transfer member according to claim 1 or 2.

6. The bonding material is positioned between adjacent graphite blocks The heat transfer member according to claim 5.

7. The heat transfer member according to claim 1 or 2; A heat source thermally connected to the heat transfer member; A support for supporting the heat transfer member; Comprising: In the first direction, the thermal expansion coefficient of the graphite block is greater than the thermal expansion coefficient of the support Electronic device.

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