Graphite composite and method for producing graphite composite

Abstract

In order to realize a graphite composite that has excellent thermal diffusion ability, is resistant to cracking of anisotropic graphite, has excellent heat resistance, and has a small degree of warpage, the present invention uses a graphite composite (103) provided with: anisotropic graphite (1) having a crystal orientation plane (20) of a graphite layer disposed parallel to the XZ plane in an XYZ space and having a first main surface (30) and a second main surface (31) that are parallel to the XY plane; a first metal layer (3) on the first main surface and a second metal layer (4) on the second main surface that have a specific thickness; and an adhesive layer (11) and a reinforcing layer (10) that are parallel to the YZ plane.

Description

Graphite composite and method for producing the graphite composite

[0001] The present invention relates to a graphite composite and a method for producing the graphite composite.

[0002] Graphite is widely used as an element for transferring and dissipating heat generated in electronic equipment and devices.

[0003] In particular, anisotropic graphite, which has a graphite structure in which six-membered rings of carbon atoms are connected by covalent bonds and in which the graphite structures are bonded together by van der Waals forces, has high thermal conductivity, and therefore has attracted attention as an element that can effectively transfer and dissipate heat generated from electronic devices and electronic equipment.

[0004] For example, Patent Document 1 discloses anisotropic graphite, anisotropic graphite composites, and a manufacturing method thereof, which are heat transfer elements having excellent heat transfer performance and long-term reliability. In the technology described in Patent Document 1, a titanium-containing metal layer, an inorganic material layer, and the like are formed on the main surface of anisotropic graphite.

[0005] WO2019 / 188915 A1

[0006] Although the above-described conventional techniques are excellent, there is room for improvement in the conventional techniques in terms of simultaneously achieving improved heat diffusion capability, making the anisotropic graphite less likely to crack, improving heat resistance, and reducing the degree of warpage.

[0007] An object of one aspect of the present invention is to provide a graphite composite having excellent thermal diffusion capability, anisotropic graphite that is less likely to crack, excellent heat resistance, and a small degree of warping.

[0008] A graphite composite according to one embodiment of the present invention is a graphite composite comprising: anisotropic graphite, the crystal orientation plane of which is arranged parallel to the X-Z plane, where the X axis is an X axis, the Y axis is orthogonal to the X axis, and the Z axis is perpendicular to the X-Y plane; the anisotropic graphite having a first main surface parallel to the X-Y plane and a second main surface opposite the first main surface; a first metal layer provided on the first main surface of the anisotropic graphite; a second metal layer provided on the second main surface of the anisotropic graphite; and an adhesive layer and a reinforcing layer provided on at least one of the surfaces of the anisotropic graphite parallel to the Y-Z plane, wherein the first metal layer and the second metal layer have thicknesses of 2 μm to 50 μm, and the adhesive layer contains a resin.

[0009] A method for producing a graphite composite according to one embodiment of the present invention is a method for producing a graphite composite comprising anisotropic graphite, the crystal orientation plane of which is oriented parallel to the X-Z plane, the anisotropic graphite having a first main surface parallel to the X-Y plane and a second main surface opposite the first main surface, where X axis, Y axis orthogonal to the X axis, and Z axis perpendicular to the X-Y plane are defined as the X axis, Y axis perpendicular to the X-axis, and Z axis perpendicular to the X-Y plane, the method comprising: a reinforcing step of forming a reinforcing layer on at least one of the surfaces of the anisotropic graphite parallel to the Y-Z plane, the reinforcing step bonding the anisotropic graphite and the reinforcing layer together via an adhesive layer; and a metal layer forming step of forming a first metal layer and a second metal layer, respectively, on the first main surface and the second main surface of the anisotropic graphite on which the reinforcing layer has been formed, wherein the first metal layer and the second metal layer have thicknesses of 2 μm to 50 μm, and the adhesive layer contains a resin.

[0010] According to one aspect of the present invention, it is possible to provide a graphite composite having excellent thermal diffusion ability, anisotropic graphite that is less likely to crack, excellent heat resistance, and a small degree of warping.

[0011] The present invention relates to a graphite composite having a heat transfer performance evaluation test and a graphite composite having a heat transfer coefficient evaluation test.

[0012] An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0013] [1. Basic Principle of the Present Invention] As described above, in the technology described in Patent Document 1, a titanium-containing metal layer, an inorganic material layer, and the like are formed on the main surface of anisotropic graphite. The inorganic material layer disposed on the main surface of the anisotropic graphite tends to inhibit the excellent heat diffusion ability of the anisotropic graphite. Furthermore, anisotropic graphite has the property of being easily cracked along the crystal orientation plane of the graphite layer.

[0014] The present inventors have discovered the following (i) to (iv) and have completed the present invention.

[0015] (i) The uniquely arranged reinforcing layer makes the anisotropic graphite less likely to crack.

[0016] (ii) Because the reinforcing layer is provided, the layer surrounding the anisotropic graphite can be made thinner and the configuration of the layer surrounding the anisotropic graphite can be simplified, thereby improving the heat diffusion capacity of the graphite composite.

[0017] (iii) The thin layer surrounding the anisotropic graphite makes the anisotropic graphite even more resistant to cracking.

[0018] (iv) The degree of warping of the anisotropic graphite can be reduced by using an adhesive layer having a unique arrangement and composition. Here, the layer surrounding the anisotropic graphite is, for example, a metal layer such as a first metal layer and a second metal layer. Furthermore, simplifying the configuration of the layer surrounding the anisotropic graphite can mean, for example, that the configuration provided on the main surface of the anisotropic graphite is limited to the first metal layer and the second metal layer.

[0019] According to one aspect of the present invention, it is possible to provide a graphite composite having excellent thermal diffusion ability, anisotropic graphite that is less likely to crack, excellent heat resistance, and a small degree of warping. Such effects according to one aspect of the present invention may also contribute to the achievement of, for example, Goal 12 of the Sustainable Development Goals (SDGs) proposed by the United Nations, "Ensure sustainable consumption and production patterns."

[0020] 2. Graphite Composite A graphite composite according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of a graphite composite according to one embodiment of the present invention.

[0021] Graphite composite 103 according to one embodiment of the present invention is a graphite composite comprising: anisotropic graphite 1, in which crystal orientation plane 20 of the graphite layer is arranged parallel to the X-Z plane, where X axis, Y axis orthogonal to the X axis, and Z axis perpendicular to the X-Y plane are taken as the axes; first main surface 30 parallel to the X-Y plane and second main surface 31 opposite first main surface 30; first metal layer 3 provided on first main surface 30 of anisotropic graphite 1; second metal layer 4 provided on second main surface 31 of anisotropic graphite 1; and adhesive layer 11 and reinforcing layer 10 provided on at least one of the surfaces of anisotropic graphite 1 parallel to the Y-Z plane, wherein first metal layer 3 and second metal layer 4 have thicknesses of 2 μm to 50 μm, and adhesive layer 11 contains a resin.

[0022] As shown in 101 in Fig. 1 , a graphite composite according to one embodiment of the present invention includes anisotropic graphite 1. As shown in 101 in Fig. 1 , anisotropic graphite 1 is formed by arranging crystal orientation plane 20 of a graphite layer parallel to the X-Z plane, and has first main surface 30 parallel to the X-Y plane and second main surface 31 opposite to first main surface 30.

[0023] Anisotropic graphite 1 may have a block-like shape (e.g., a cube or a rectangular parallelepiped) in which multiple layers (i.e., graphite layers) having a graphite structure in which six-membered rings are connected by covalent bonds are stacked. Anisotropic graphite 1 may be stacked such that the layers having the graphite structure are in direct contact with each other, or may be stacked via an adhesive (e.g., adhesive, double-sided tape) between them. Block-like anisotropic graphite has high thermal conductivity in directions parallel to the crystal orientation planes 20 of the graphite layers (e.g., the X-axis direction and the Z-axis direction). The "anisotropy" of anisotropic graphite 1 means that, due to the orientation of the graphite layers, the thermal conductivity of anisotropic graphite 1 differs significantly in directions parallel to the crystal orientation planes 20 of the graphite layers (e.g., the X-axis direction and the Z-axis direction) and in a direction perpendicular to the crystal orientation planes 20 of the graphite layers (e.g., the Y-axis direction). Such anisotropic graphite 1 can be suitably produced using a known method such as the method described in the above-mentioned Patent Document 1.

[0024] The thermal conductivity of anisotropic graphite 1 in the X-axis direction and the Z-axis direction may be, for example, 1000 W / mK or more. The upper limits of the thermal conductivity of anisotropic graphite 1 in the X-axis direction and the Z-axis direction are not particularly limited, but may be 2000 W / mK or less. On the other hand, the thermal conductivity of anisotropic graphite 1 in the Y-axis direction may be, for example, 0.3 W / mK or more and 20 W / mK or less.

[0025] First main surface 30 is a surface parallel to the X-Y plane, and second main surface 31 is a surface opposite first main surface 30 parallel to the X-Y plane (in other words, a surface parallel to the X-Y plane). Therefore, anisotropic graphite 1 can efficiently transport heat along the Z-axis direction (e.g., from first main surface 30 to second main surface 31) and / or along the X-axis direction.

[0026] The thickness of the anisotropic graphite 1 (thickness in the Z-axis direction) is not limited, but is preferably 0.3 mm to 5.0 mm, more preferably 0.5 mm to 3.0 mm, and most preferably 0.7 mm to 2.0 mm. With this configuration, a thin heat transfer element capable of efficiently transporting heat can be realized.

[0027] The thickness of the anisotropic graphite 1 in the X-axis direction and the Y-axis direction is not limited and can be set appropriately depending on the intended use. The thickness of the anisotropic graphite in the X-axis direction and the Y-axis direction can be, for example, 10 mm to 80 mm, or 10 mm to 50 mm.

[0028] As shown in FIG. 1 , a graphite composite 103 according to one embodiment of the present invention includes a first metal layer 3 provided on a first main surface 30 of anisotropic graphite 1, and a second metal layer 4 provided on a second main surface 31 of anisotropic graphite 1.

[0029] As described above, in anisotropic graphite 1, heat is efficiently transported along the Z-axis direction, and therefore, first metal layer 3 and second metal layer 4 can efficiently transfer heat from anisotropic graphite 1 to other components.

[0030] Furthermore, first metal layer 3 and second metal layer 4 cover at least a portion of the surface of anisotropic graphite 1, thereby preventing graphite powder from falling off anisotropic graphite 1. If graphite powder can be prevented from falling off anisotropic graphite 1, then when a graphite composite according to one embodiment of the present invention is placed in an electronic device, for example, it is possible to prevent short circuits in electronic circuits caused by the graphite powder.

[0031] Furthermore, first metal layer 3 and second metal layer 4 can make anisotropic graphite 1 even more difficult to crack.

[0032] The first metal layer 3 and the second metal layer 4 may be provided so as to be in direct contact with the anisotropic graphite 1, or may be provided so as not to be in direct contact with the anisotropic graphite 1. The first metal layer 3 and the second metal layer 4 are preferably provided so as to be in direct contact with the anisotropic graphite 1. With this configuration, heat can be directly transferred between the anisotropic graphite 1 and the first metal layer 3 and the second metal layer 4, thereby realizing a thin heat transfer element that can efficiently transport heat. Furthermore, with this configuration, the first metal layer 3 and the second metal layer 4 can more reliably cover at least a portion of the surface of the anisotropic graphite 1 and can more reliably make the anisotropic graphite 1 less susceptible to cracking.

[0033] The configuration of the first metal layer 3 and the second metal layer 4 is not particularly limited, but is preferably a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plated layer, or a metal layer containing a metallic brazing material, and more preferably a plated layer. The plated layer may be a combination of a metal layer and an inorganic material layer. This configuration allows the first metal layer 3 and the second metal layer 4 to be thin, thereby realizing a thin heat transfer element that can efficiently transport heat. Furthermore, this configuration allows the first metal layer 3 and the second metal layer 4 to be formed on the anisotropic graphite 1 without any other intervening structure.

[0034] The materials for the first metal layer 3 and the second metal layer 4 are not particularly limited, but preferably contain at least one selected from the group consisting of copper, nickel, and gold. Of these materials, copper is more preferred. With this configuration, a heat transfer element that is both cost-effective and provides efficient heat transfer can be realized.

[0035] The thickness (thickness in the Z-axis direction) of the first metal layer 3 and the second metal layer 4 can be 2 μm to 50 μm, preferably 3 μm to 30 μm, and more preferably 5 μm to 10 μm. With this configuration, a heat transfer element capable of more efficient heat transport can be realized.

[0036] As shown in FIG. 1 , in graphite composite 103 according to one embodiment of the present invention, third metal layer 5 and fourth metal layer 6 are preferably provided on both surfaces of the outermost layers of anisotropic graphite 1 that are parallel to the XZ plane.

[0037] Since at least a portion of the surface of anisotropic graphite 1 is covered with third metal layer 5 and fourth metal layer 6, graphite powder can be prevented from falling off from anisotropic graphite 1.

[0038] Additionally, third metal layer 5 and fourth metal layer 6 can make anisotropic graphite 1 even more difficult to crack.

[0039] Third metal layer 5 and fourth metal layer 6 may be provided so as to be in direct contact with anisotropic graphite 1, or so as not to be in direct contact with anisotropic graphite 1. Third metal layer 5 and fourth metal layer 6 are preferably provided so as to be in direct contact with anisotropic graphite 1. With this configuration, third metal layer 5 and fourth metal layer 6 can more reliably cover at least a portion of the surface of anisotropic graphite 1, and can more reliably make anisotropic graphite 1 less susceptible to cracking.

[0040] The configurations of the third metal layer 5 and the fourth metal layer 6 may be similar to those of the first metal layer 3 and the second metal layer 4 .

[0041] The thicknesses (thickness in the Y-axis direction) of third metal layer 5 and fourth metal layer 6 are not particularly limited, but are preferably 2 μm to 50 μm, more preferably 3 μm to 30 μm, and most preferably 5 μm to 10 μm. This configuration not only prevents graphite powder from falling off anisotropic graphite 1, but also enables the realization of a thin heat transfer element.

[0042] As shown in Figure 1, graphite composite 103 according to one embodiment of the present invention includes reinforcing layer 10 provided on at least one of the surfaces parallel to the Y-Z plane of anisotropic graphite 1. In graphite composite 103 according to one embodiment of the present invention, reinforcing layer 10 is preferably provided on both of the surfaces parallel to the Y-Z plane of anisotropic graphite 1. Reference numeral 102 in Figure 1 schematically shows a configuration in which first metal layer 3, second metal layer 4, third metal layer 5, and fourth metal layer 6 are not provided.

[0043] Anisotropic graphite has the property of being easily cracked along the XZ plane (crystal orientation plane 20). Therefore, by providing reinforcing layer 10 on at least one of the surfaces parallel to the YZ plane, anisotropic graphite 1 can be made less likely to crack.

[0044] The reinforcing layer may also be formed on the X-Z plane. That is, a graphite composite according to one embodiment of the present invention may include a reinforcing layer provided on at least one of the surfaces of the anisotropic graphite parallel to the X-Z plane (or on both of the surfaces parallel to the X-Z plane).

[0045] The configuration outside the X-Z plane of the anisotropic graphite can be the same as the configuration outside the Y-Z plane of the anisotropic graphite, such as a configuration including reinforcing layer 10, a configuration including reinforcing layer 10 and adhesive layer 11, or a configuration including reinforcing layer 10, adhesive layer 11, and a seventh metal layer.

[0046] The thickness of reinforcing layer 10 (thickness in the X-axis direction) is not limited, but is preferably 50 μm to 500 μm, more preferably 100 μm to 400 μm, and most preferably 150 μm to 300 μm. This configuration not only makes anisotropic graphite 1 less likely to crack, but also enables the realization of a thin heat transfer element.

[0047] The thickness of reinforcing layer 10 in the Y-axis direction and the Z-axis direction is not limited, and can be set appropriately in accordance with the size of anisotropic graphite 1 .

[0048] The material of the reinforcing layer 10 is not particularly limited, but preferably includes at least one selected from the group consisting of resin, metal, and ceramic. Examples of the resin include acrylic resin, polypropylene, polyethylene, polyethylene terephthalate, polycarbonate, modified resins containing various additives, and elastomers. Examples of the metal include gold, silver, copper, nickel, aluminum, molybdenum, tungsten, alloys containing these, and metallic brazing filler metals. Examples of the ceramic include alumina, zirconia, silicon carbide, silicon nitride, boron nitride, and aluminum nitride. This configuration provides the advantage of making the anisotropic graphite 1 less likely to crack. From the perspective of further achieving this advantage, polycarbonate and polyethylene terephthalate are more preferred among the resins, copper and aluminum are more preferred among the metals, and alumina and silicon carbide are more preferred among the ceramics.

[0049] As shown in Fig. 1 , a graphite composite according to one embodiment of the present invention includes adhesive layer 11 between anisotropic graphite 1 and reinforcing layer 10. According to this configuration, anisotropic graphite 1 and reinforcing layer 10 can be bonded together via adhesive layer 11.

[0050] The adhesive layer 11 contains a resin. The resin is not limited and may be, for example, at least one selected from the group consisting of a thermosetting resin and a thermoplastic resin. More specifically, the resin may be at least one selected from the group consisting of an acrylic resin, a silicone resin, an epoxy resin, an ester resin, a phenolic resin, a polyimide resin, and a urethane resin. The resin may also be at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin. The adhesive layer 11 may contain components other than resin.

[0051] The thickness of adhesive layer 11 (thickness in the X-axis direction) is not limited, but is preferably 5 μm to 500 μm, more preferably 8 μm to 100 μm, and most preferably 8 μm to 50 μm. This configuration not only enables anisotropic graphite 1 and reinforcing layer 10 to be firmly bonded together, but also enables a thin heat transfer element to be realized.

[0052] The thickness of adhesive layer 11 in the Y-axis direction and the Z-axis direction is not limited, and can be set appropriately in accordance with the size of anisotropic graphite 1 .

[0053] Graphite composite 103 according to one embodiment of the present invention may include fifth metal layer 7 on the outer side of reinforcing layer 10 (in other words, on the side of reinforcing layer 10 opposite adhesive layer 11).

[0054] Since fifth metal layer 7 covers at least a portion of the surface of reinforcing layer 10 (in other words, at least a portion of the surface of anisotropic graphite 1), it is possible to better prevent graphite powder from falling off from anisotropic graphite 1.

[0055] Furthermore, fifth metal layer 7 can make anisotropic graphite 1 even more difficult to crack.

[0056] The configuration of the fifth metal layer 7 is not particularly limited, but may be the same as that of the first metal layer 3 and the second metal layer 4 .

[0057] The thickness of fifth metal layer 7 (thickness in the X-axis direction) is not particularly limited, but is preferably 2 μm to 50 μm, more preferably 3 μm to 50 μm, and most preferably 5 μm to 10 μm. This configuration not only prevents graphite powder from falling off anisotropic graphite 1, but also enables the realization of a thin heat transfer element.

[0058] The thickness of fifth metal layer 7 in the Y-axis direction and the Z-axis direction is not limited, and can be set appropriately in accordance with the size of anisotropic graphite 1 .

[0059] 2. Manufacturing Method of Graphite Composite A manufacturing method of a graphite composite 103 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Note that the contents already explained in the above section [1. Graphite Composite] will not be explained here.

[0060] A manufacturing method of graphite composite 103 according to one embodiment of the present invention is a manufacturing method of graphite composite 103 including anisotropic graphite 1, in which, when taken as an X axis, a Y axis orthogonal to the X axis, and a Z axis perpendicular to the X-Y plane, crystal orientation plane 20 of the graphite layer is oriented parallel to the X-Z plane, and the anisotropic graphite has first main surface 30 parallel to the X-Y plane and second main surface 31 opposite first main surface 30, the manufacturing method including: a reinforcing step of forming reinforcing layer 10 on at least one of the surfaces of anisotropic graphite 1 parallel to the Y-Z plane, the reinforcing step bonding anisotropic graphite 1 and reinforcing layer 10 via adhesive layer 11; and a metal layer forming step of forming first metal layer 3 and second metal layer 4 on first main surface 30 and second main surface 31 of anisotropic graphite 1 on which reinforcing layer 10 has been formed, respectively, wherein first metal layer 3 and second metal layer 4 have thicknesses of 2 μm to 50 μm, and adhesive layer 11 contains a resin.

[0061] The reinforcing step is a step of forming reinforcing layer 10 on at least one of the surfaces of anisotropic graphite 1 parallel to the YZ plane (or on both of the surfaces of anisotropic graphite 1 parallel to the YZ plane) (see step 1 in FIG. 2).

[0062] The specific configuration of the reinforcing step is not particularly limited, and for example, anisotropic graphite 1 and reinforcing layer 10 may be bonded together via adhesive layer 11. Note that as a method for bonding anisotropic graphite 1 and reinforcing layer 10 together via adhesive layer 11, any known method may be used as appropriate depending on the raw material of adhesive layer 11.

[0063] The adhesive layer 11 contains a resin. The resin is not limited and may be, for example, at least one selected from the group consisting of a thermosetting resin and a thermoplastic resin. More specifically, the resin may be at least one selected from the group consisting of an acrylic resin, a silicone resin, an epoxy resin, an ester resin, a phenolic resin, a polyimide resin, and a urethane resin. The resin may also be at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin. The adhesive layer 11 may contain components other than resin.

[0064] The method for manufacturing graphite composite 103 according to one embodiment of the present invention preferably includes, after the reinforcing step, a cutting step of cutting reinforcing layer 10 and anisotropic graphite 1 (in other words, a composite of reinforcing layer 10 and anisotropic graphite 1).

[0065] In the cutting step, for example, the composite of reinforcing layer 10 and anisotropic graphite 1 can be cut along cutting plane 50 parallel to the XY plane (see steps 2 and 3 in FIG. 2 ). This configuration allows a plurality of precursors of graphite composite 103 to be obtained from one large block. Furthermore, a plurality of graphite composites 103 can be efficiently produced from the precursors.

[0066] The specific steps of the cutting step are not particularly limited, and examples thereof include cutting with a wire saw, cutting with a mold, and cutting with a laser. Of these, cutting with a wire saw is preferred because it has the advantage of improving productivity.

[0067] The metal layer forming step is a step of forming a first metal layer 3 and a second metal layer 4 on the first main surface 30 and the second main surface 31, respectively, of anisotropic graphite 1 on which reinforcing layer 10 has been formed (see step 4 in Figure 2).

[0068] In the metal layer forming step, it is preferable to simultaneously form the first metal layer 3 and the second metal layer 4. According to this configuration, the graphite complex can be produced efficiently.

[0069] In the metal layer forming step, the first metal layer 3, the second metal layer 4, the third metal layer 5, and the fourth metal layer 6 may be formed simultaneously. Furthermore, in the metal layer forming step, in addition to the first metal layer 3 to the fourth metal layer 6, a fifth metal layer 7 may also be formed simultaneously. Furthermore, in the metal layer forming step, the fifth metal layer may be formed simultaneously with the first metal layer and the second metal layer without forming the third metal layer and / or the fourth metal layer. This configuration allows for efficient production of a graphite composite that can better prevent graphite powder from falling off from anisotropic graphite 1.

[0070] The method for forming the first metal layer 3, the second metal layer 4, the third metal layer 5, the fourth metal layer 6, and the fifth metal layer 7 is not particularly limited, and any known method can be used as appropriate depending on the raw materials of these metal layers. Examples of such methods include plating, attaching a metal film with an adhesive, metal vapor deposition, and sputtering. According to this configuration, metal layers such as the first metal layer 3 and the second metal layer 4 can be formed directly on a structure such as anisotropic graphite 1.

[0071] When a reinforcing layer 10 is provided on anisotropic graphite 1 after a metal layer has been formed on the anisotropic graphite 1 by plating or the like, the anisotropic graphite 1 needs to be placed in a plating tank while being held by a holding tool during the plating process. Examples of the metal layer include a first metal layer 3, a second metal layer 4, a third metal layer 5, a fourth metal layer 6, and a fifth metal layer 7. In this case, portions of the surface of anisotropic graphite 1 that are in contact with the holding tool are likely to have no metal layer formed thereon. This can cause a problem in that graphite powder is likely to fall off from anisotropic graphite 1. Another problem can arise in that anisotropic graphite 1 is prone to cracking due to vibrations or the like that occur when the metal layer is formed.

[0072] The above-mentioned problems can be solved by performing the metal layer forming step after the reinforcing step.

[0073] One embodiment of the present invention includes the inventions described in [1] to

[50] below.

[0074] [1] A graphite composite comprising: anisotropic graphite, the crystal orientation plane of which is arranged parallel to the X-Z plane, where X axis, Y axis orthogonal to the X axis, and Z axis perpendicular to the X-Y plane are defined; the anisotropic graphite having a first main surface parallel to the X-Y plane and a second main surface opposite to the first main surface; a first metal layer provided on the first main surface of the anisotropic graphite; a second metal layer provided on the second main surface of the anisotropic graphite; and an adhesive layer and a reinforcing layer provided on at least one of the surfaces of the anisotropic graphite parallel to the Y-Z plane, wherein the first metal layer and the second metal layer have thicknesses of 2 μm to 50 μm, and the adhesive layer contains a resin.

[0075] [2] The graphite complex according to [1], wherein the thickness of the anisotropic graphite in the X-axis direction and the Y-axis direction is 10 mm to 80 mm.

[0076] [3] The graphite complex according to [1] or [2], wherein the thickness of the anisotropic graphite in the Z-axis direction is 0.3 mm to 5.0 mm.

[0077] [4] The graphite complex according to any one of [1] to [3], wherein the reinforcing layer has a thickness of 50 μm to 500 μm.

[0078] [5] The graphite composite according to any one of [1] to [4], wherein the resin contained in the adhesive layer is at least one selected from the group consisting of a thermosetting resin and a thermoplastic resin.

[0079] [6] The graphite composite according to any one of [1] to [5], wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, an epoxy resin, an ester resin, a phenolic resin, a polyimide resin, and a urethane resin.

[0080] [7] The graphite composite according to any one of [1] to [6], wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin.

[0081] [8] The graphite composite according to any one of [1] to [7], wherein the first metal layer and the second metal layer are in direct contact with the anisotropic graphite.

[0082] [9] The graphite composite according to any one of [1] to [8], wherein the first metal layer and the second metal layer are a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metal-based brazing filler metal.

[0083]

[10] The graphite composite according to any one of [1] to [9], wherein the first metal layer and the second metal layer contain at least one metal selected from the group consisting of copper, nickel, and gold.

[0084]

[11] The graphite complex according to any one of [1] to

[10] , wherein the thickness of the first metal layer and the second metal layer in the Z-axis direction is 2 μm to 50 μm.

[0085]

[12] The graphite composite according to any one of [1] to

[11] , wherein the reinforcing layer contains at least one material selected from the group consisting of a resin, a metal, and a ceramic.

[0086]

[13] The graphite composite according to any one of [1] to

[12] , wherein the reinforcing layers are provided on both surfaces of the anisotropic graphite that are parallel to the YZ plane.

[0087]

[14] The graphite complex according to any one of [1] to

[13] , wherein the thickness of the reinforcing layer in the X-axis direction is 50 μm to 500 μm.

[0088]

[15] The graphite composite according to any one of [1] to

[14] , wherein a third metal layer and a fourth metal layer are provided on both surfaces of the outermost layer of the anisotropic graphite that are parallel to the XZ plane.

[0089]

[16] The graphite composite according to

[15] , wherein the third metal layer and the fourth metal layer are in direct contact with the anisotropic graphite.

[0090]

[17] The graphite composite according to

[15] or

[16] , wherein the third metal layer and the fourth metal layer are a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metal-based brazing filler metal.

[0091]

[18] The graphite composite according to any one of

[15] to

[17] , wherein the third metal layer and the fourth metal layer contain at least one metal selected from the group consisting of copper, nickel, and gold.

[0092]

[19] The graphite complex according to any one of

[15] to

[18] , wherein the thickness of the third metal layer and the fourth metal layer in the Y-axis direction is 2 μm to 50 μm.

[0093]

[20] The graphite complex according to any one of [1] to

[19] , further comprising a fifth metal layer on the outside of the reinforcing layer.

[0094]

[21] The graphite composite according to

[20] , wherein the fifth metal layer is a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metallic brazing filler metal.

[0095]

[22] The graphite composite according to

[20] or

[21] , wherein the fifth metal layer contains at least one selected from the group consisting of copper, nickel, and gold.

[0096]

[23] The graphite complex according to any one of

[20] to

[22] , wherein the thickness of the fifth metal layer in the X-axis direction is 2 μm to 50 μm.

[0097]

[24] A method for producing a graphite composite including anisotropic graphite, the crystal orientation plane of which is arranged parallel to the X-Z plane, where X axis, Y axis orthogonal to the X axis, and Z axis perpendicular to the X-Y plane are defined as the X axis, and the anisotropic graphite has a first main surface parallel to the X-Y plane and a second main surface opposite to the first main surface, the method comprising: a reinforcing step of forming a reinforcing layer on at least one of the surfaces of the anisotropic graphite parallel to the Y-Z plane, the reinforcing step bonding the anisotropic graphite and the reinforcing layer via an adhesive layer; and a metal layer forming step of forming a first metal layer and a second metal layer, respectively, on the first main surface and the second main surface of the anisotropic graphite on which the reinforcing layer has been formed, wherein the first metal layer and the second metal layer have thicknesses of 2 μm to 50 μm, and the adhesive layer contains a resin.

[0098]

[25] The method for producing a graphite composite according to

[24] , wherein the thickness of the anisotropic graphite in the X-axis direction and the Y-axis direction is 10 mm to 80 mm.

[0099]

[26] The method for producing a graphite composite according to

[24] or

[25] , wherein the thickness of the anisotropic graphite in the Z-axis direction is 0.3 mm to 5.0 mm.

[0100]

[27] The method for producing a graphite composite according to any one of

[24] to

[26] , wherein the reinforcing layer has a thickness of 50 μm to 500 μm.

[0101]

[28] The method for producing a graphite composite according to any one of

[24] to

[27] , further comprising, after the reinforcing step, a cutting step of cutting the reinforcing layer and the anisotropic graphite.

[0102]

[29] The method for producing a graphite composite according to any one of

[28] , wherein the cutting step is a step of cutting the reinforcing layer and the anisotropic graphite along a cutting plane parallel to an XY plane.

[0103]

[30] The method for producing a graphite composite according to either

[28] or

[29] , wherein the cutting step is a step of cutting the reinforcing layer and the anisotropic graphite by a method selected from the group consisting of cutting with a wire saw, cutting with a die, and cutting with a laser.

[0104]

[31] The method for producing a graphite composite according to any one of

[24] to

[30] , wherein the resin contained in the adhesive layer is at least one selected from the group consisting of a thermosetting resin and a thermoplastic resin.

[0105]

[32] The method for producing a graphite composite according to any one of

[24] to

[31] , wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, an epoxy resin, an ester resin, a phenolic resin, a polyimide resin, and a urethane resin.

[0106]

[33] The method for producing a graphite composite according to any one of

[24] to

[32] , wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin.

[0107]

[34] The method for producing a graphite composite according to any one of

[24] to

[33] , wherein the first metal layer and the second metal layer are formed simultaneously in the metal layer forming step.

[0108]

[35] The method for producing a graphite composite according to any one of

[24] to

[34] , wherein in the metal layer forming step, the first metal layer and the second metal layer are formed so as to be in direct contact with the anisotropic graphite.

[0109]

[36] The method for producing a graphite composite according to any one of

[24] to

[35] , wherein the first metal layer and the second metal layer are a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metal-based brazing filler metal.

[0110]

[37] The method for producing a graphite composite according to any one of

[24] to

[36] , wherein the first metal layer and the second metal layer contain at least one metal selected from the group consisting of copper, nickel, and gold.

[0111]

[38] The method for producing a graphite composite according to any one of

[24] to

[37] , wherein the thickness of the first metal layer and the second metal layer in the Z-axis direction is 2 μm to 50 μm.

[0112]

[39] The method for producing a graphite composite according to any one of

[24] to

[38] , wherein the reinforcing layer contains at least one material selected from the group consisting of a resin, a metal, and a ceramic.

[0113]

[40] The method for producing a graphite composite according to any one of

[24] to

[39] , wherein in the reinforcing step, the reinforcing layers are provided on both surfaces of the anisotropic graphite that are parallel to the YZ plane.

[0114]

[41] The method for producing a graphite composite according to any one of

[24] to

[40] , wherein the reinforcing layer has a thickness in the X-axis direction of 50 μm to 500 μm.

[0115]

[42] The method for producing a graphite composite according to any one of

[24] to

[41] , wherein the metal layer-forming step further comprises forming a third metal layer and a fourth metal layer on both sides of an outermost layer of the anisotropic graphite that is parallel to the XZ plane.

[0116]

[43] The method for producing a graphite composite according to

[42] , wherein in the metal layer forming step, the third metal layer and the fourth metal layer are formed so as to be in direct contact with the anisotropic graphite.

[0117]

[44] The method for producing a graphite composite according to

[42] or

[43] , wherein the third metal layer and the fourth metal layer are a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metal-based brazing filler metal.

[0118]

[45] The method for producing a graphite composite according to any one of

[42] to

[44] , wherein the third metal layer and the fourth metal layer contain at least one metal selected from the group consisting of copper, nickel, and gold.

[0119]

[46] The method for producing a graphite composite according to any one of

[42] to

[45] , wherein the thickness of the third metal layer and the fourth metal layer in the Y-axis direction is 2 μm to 50 μm.

[0120]

[47] The method for producing a graphite composite according to any one of

[42] to

[46] , wherein the metal layer forming step further comprises forming a fifth metal layer on the outer side of the reinforcing layer.

[0121]

[48] ​​The method for producing a graphite composite according to

[47] , wherein the fifth metal layer is a metal vapor deposition layer, a metal layer formed by sputtering, a metal layer formed by thermal spraying, a plating layer, or a metal layer containing a metal-based brazing filler metal.

[0122]

[49] The method for producing a graphite composite according to

[47] or

[48] , wherein the fifth metal layer contains at least one selected from the group consisting of copper, nickel, and gold.

[0123]

[50] The method for producing a graphite composite according to any one of

[47] to

[49] , wherein the fifth metal layer has a thickness in the X-axis direction of 2 μm to 50 μm.

[0124] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these.

[0125] <Production of Anisotropic Graphite and Graphite Composite> (Graphite Composite (A): Example 1) 4,500 sheets of polyimide film each having a size of 100 mm x 100 mm x 25 μm in thickness were laminated. ２ A graphite block (90 mm x 90 mm, thickness 45 mm) was produced by heat-treating the sample in an argon atmosphere up to 2900°C while pressing the sample at a pressure of 1000 kJ / cm2. The thermal conductivity of the obtained graphite block was 1500 W / mK in a direction parallel to the crystal orientation plane and 5 W / mK in a direction perpendicular to the crystal orientation plane.

[0126] The obtained graphite block (90 mm × 90 mm, thickness 45 mm) was cut with a wire saw to obtain anisotropic graphite 1. When the crystal orientation plane of anisotropic graphite 1 was placed parallel to the X-axis, the length of the side parallel to the X-axis was 39.6 mm, the length of the side parallel to the Y-axis was 29.99 mm, and the length of the side parallel to the Z-axis was 80 mm.

[0127] Next, oxygen-free copper as reinforcing layer 10, measuring 29.99 mm x 80 mm x 150 μm thick, was bonded to both surfaces of anisotropic graphite 1 parallel to the YZ plane via acrylic double-sided tape as adhesive layer 11, measuring 29.99 mm x 80 mm x 50 μm.

[0128] This method yielded a composite having a side parallel to the X axis of 40 mm, a side parallel to the Y axis of 29.99 mm, and a side parallel to the Z axis of 80 mm.

[0129] The composite was then cut parallel to the X-Y plane using a wire saw to obtain composites of any desired thickness. The obtained composite was then plated to deposit a 5 μm thick layer of copper on the surface, yielding a metal-coated graphite composite (A). This coating corresponds to the first metal layer 3 and the second metal layer 4.

[0130] The center of 301 in Figure 3 shows an outline of the configuration of graphite composite (A), and the dimensions of graphite composite (A) are given below: - Size of anisotropic graphite 1 in the X-Y plane: 39.6 mm x 29.99 mm, - Thickness of anisotropic graphite 1 in the Z-axis direction: 0.99 mm, - Thickness of first metal layer 3 and second metal layer 4 in the Z-axis direction: 5 μm, - Thickness of adhesive layer 11 in the X-axis direction: 50 μm, - Thickness of adhesive layer 11 in the Z-axis direction: 0.99 mm, - Thermal conductivity of adhesive layer 11: 0.2 W / mK, - Thickness of reinforcing layer 10 in the X-axis direction: 150 μm, - Thickness of reinforcing layer 10 in the Z-axis direction: 0.99 mm.

[0131] Example 2 A graphite composite (B) was obtained in the same manner as in Example 1, except that a silicone double-sided tape was used instead of the acrylic double-sided tape.

[0132] Example 3 A graphite composite (C) was obtained in the same manner as in Example 1, except that an epoxy resin tape was used instead of the acrylic double-sided tape and the copper plate was adhered at 180°C.

[0133] Example 4 A graphite composite (D) was obtained in the same manner as in Example 1, except that an acrylic plate was used for the reinforcing layer instead of the oxygen-free copper plate.

[0134] Example 5 A graphite composite (E) was obtained in the same manner as in Example 2, except that an acrylic plate was used for the reinforcing layer instead of the oxygen-free copper plate.

[0135] Example 6 A graphite composite (F) was obtained in the same manner as in Example 3, except that an acrylic plate was used for the reinforcing layer instead of the oxygen-free copper plate.

[0136] Example 7 A graphite composite (G) was obtained in the same manner as in Example 1, except for the following (i).

[0137] (i) A graphite block (200 mm x 200 mm, 40 mm thick) was prepared by alternately laminating 36 μm thick graphite sheets manufactured by Kaneka Corporation and 5 μm thick double-sided acrylic tape. The thermal conductivity of the obtained graphite block was 1500 W / mK in the direction parallel to the crystal orientation plane and 3 W / mK in the direction perpendicular to the crystal orientation plane.

[0138] Example 8 A graphite complex (H) was obtained in the same manner as in Example 7, except that a silicone double-sided tape was used instead of the acrylic double-sided tape.

[0139] Example 9 A graphite composite (I) was obtained in the same manner as in Example 7, except that an epoxy resin tape was used instead of the acrylic double-sided tape and the copper plate was adhered at 180°C.

[0140] Example 10 A graphite composite (J) was obtained in the same manner as in Example 1, except for the following (ii).

[0141] (ii) A graphite block (200 mm x 200 mm, 40 mm thick) was produced by alternately laminating 36 μm thick graphite sheets manufactured by Kaneka Corporation and 5 μm thick polyester adhesive, followed by heat pressing at 260°C, 5 MPa, and 5 minutes. The thermal conductivity of the resulting graphite block was 1500 W / mK in the direction parallel to the crystal orientation plane, and 5 W / mK in the direction perpendicular to the crystal orientation plane.

[0142] Example 11 A graphite composite (K) was obtained in the same manner as in Example 10, except that a silicone double-sided tape was used instead of the acrylic double-sided tape.

[0143] Example 12 A graphite composite (L) was obtained in the same manner as in Example 10, except that an epoxy resin tape was used instead of the acrylic double-sided tape and the copper plate was adhered at 180°C.

[0144] Example 13 A graphite composite (M) was obtained in the same manner as in Example 1, except that the copper plating thickness was set to 20 μm.

[0145] Comparative Example 1 A graphite composite (N) was obtained in the same manner as in Example 1, except for the following (iii) and (iv).

[0146] (iii) Instead of the acrylic double-sided tape, a titanium-based active silver solder having a thickness of 10 μm was used.

[0147] (iv) 100 kg / m from the side of the reinforcing layer 10 on both sides ２ In this state, the composite of the anisotropic graphite 1, the adhesive layer 11, and the reinforcing layer 10 is subjected to a load of 1×10 －３ The bond was achieved by heating at 850°C for 30 minutes in a vacuum environment of 100 Pa.

[0148] Comparative Example 2 A graphite complex (O) was obtained in the same manner as in Example 1, except that no copper plate was attached as a reinforcing plate and copper plating was deposited directly on the side surface.

[0149] Comparative Example 3 A graphite composite (P) was obtained in the same manner as in Comparative Example 1, except for the following (v).

[0150] (v) Instead of copper plating, a titanium-based active silver solder having a thickness of 10 μm was used on the main surface, and the oxygen-free copper plate was soldered to a pressure of 100 kg / m ２ With a weight of 1 x 10 －３ The bond was achieved by heating at 850°C for 30 minutes in a vacuum environment of 100 Pa.

[0151] Comparative Example 4 A graphite composite (Q) was obtained in the same manner as in Example 1, except that, instead of copper plating, an oxygen-free copper plate was attached to the main surface using a 50 μm-thick double-sided acrylic tape at room temperature.

[0152] <Evaluation of Strength> A three-point bending test was performed at 50 mm / min using a three-point bending device (IMADA), and the stress at the time when the test sample broke was measured. A stress of 20 N or more was judged as "excellent," a stress of 12 N or more as "good," a stress of 8 N or more as "fair," and a stress of less than 8 N as "fail." Here, the strength evaluation results are "fail" meaning not good, "fair" meaning better than "fail," "good" meaning better than "fair," and "excellent" meaning better than "good," i.e., the best.

[0153] <Evaluation of Heat Resistance> The test sample was heated in an oven for 30 minutes, and the temperature at which the external shape changed was measured. Those that showed no change even at 500°C were judged as "excellent," those that showed no change even at 300°C as "good," and those that showed no change even at 200°C as "passable." Here, the evaluation results for heat resistance are as follows: "passable" means good, "good" means better than "passable," and "excellent" means better than "good," i.e., the best.

[0154] <Evaluation of Thermal Diffusivity> The thermal diffusivity of the test sample in the thickness direction was measured using a xenon flash analyzer LFA467 manufactured by Netzsch. ２ / s or more is rated "Excellent", and thermal diffusivity is 4cm ２ / s or more is rated as "good" and the thermal diffusivity is 4cm ２ / s was judged to be "poor." Here, for the thermal diffusivity evaluation results, "poor" means not good, "good" means better than "poor," and "excellent" means better than "good," i.e., the best.

[0155] <Warpage Evaluation> Using a VR-5000 manufactured by Keyence Corporation, the difference between the maximum height and the minimum height of the main surface of the test sample (maximum height - minimum height) was measured and used as the warpage of the test sample. Warpage of less than 0.05 mm was judged as "excellent", warpage of less than 0.1 mm as "good", warpage of less than 0.15 mm as "passable", and warpage of 0.15 mm or more as "fail". Here, the warpage evaluation results are as follows: "fail" means not good, "fair" means better than "fail", "good" means better than "fair", and "excellent" means better than "good", i.e., the best.

[0156] [Test Results] The test results are shown in Table 1 below. As is clear from Table 1, the graphite composite of the present invention was evaluated as being good in all of the categories of "strength," "heat resistance," "thermal diffusivity," and "warpage." That is, it was demonstrated that the graphite composite of the present invention has excellent thermal diffusivity, the anisotropic graphite is less likely to crack, the heat resistance is excellent, and the degree of warpage is small.

[0157] The present invention can be applied to heat transfer elements, and more particularly to heat transfer elements used in electronic equipment and electronic devices.

[0158] REFERENCE SIGNS LIST 1 Anisotropic graphite 3 First metal layer 4 Second metal layer 5 Third metal layer 6 Fourth metal layer 7 Fifth metal layer 10 Reinforcing layer 11 Adhesive layer 15 Copper plate 20 Crystal orientation plane 30 First main surface 31 Second main surface 50 Cut surface 100 Heat source 103 Graphite composite 110 Adhesive 120 Test sample 130 Solder layer 140 Copper plate 150 Heat transfer coefficient

Claims

1. When taking the X-axis, the Y-axis orthogonal to the X-axis, and the Z-axis perpendicular to the X-Y plane, the crystal orientation plane of the graphite layer is arranged parallel to the X-Z plane, and has an anisotropic graphite having a first main surface parallel to the X-Y plane and a second main surface facing the first main surface; a first metal layer provided on the first main surface of the anisotropic graphite; a second metal layer provided on the second main surface of the anisotropic graphite; an adhesive layer and a reinforcing layer provided on at least one surface of the surface parallel to the Y-Z plane in the anisotropic graphite, wherein the thicknesses of the first metal layer and the second metal layer are 2 μm to 50 μm, and the adhesive layer is a graphite composite containing a resin.

2. The graphite composite according to claim 1, wherein the thickness in the X-axis direction and the thickness in the Y-axis direction of the anisotropic graphite are 10 mm to 80 mm, and the thickness in the Z-axis direction is 0.3 mm to 5.0 mm.

3. The graphite composite according to claim 1, wherein the thickness of the reinforcing layer is 50 μm to 500 μm.

4. The graphite composite according to claim 1, wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin.

5. The graphite composite according to claim 1, wherein the first metal layer and the second metal layer are in direct contact with the anisotropic graphite.

6. The graphite composite according to claim 1, wherein the first metal layer and the second metal layer contain at least one selected from the group consisting of copper, nickel, and gold.

7. The graphite composite according to claim 1, wherein the reinforcing layer contains at least one selected from the group consisting of a resin, a metal, and a ceramic.

8. The graphite composite according to claim 1, wherein the reinforcing layer is provided on both surfaces of the surface parallel to the Y-Z plane in the anisotropic graphite.

9. The graphite composite according to claim 1, wherein a third metal layer and a fourth metal layer are respectively provided on both surfaces of the outermost layer of the surface parallel to the X-Z plane in the anisotropic graphite.

10. The graphite composite according to claim 9, wherein the third metal layer and the fourth metal layer are in direct contact with the anisotropic graphite.

11. Further, the graphite composite according to claim 1, comprising a fifth metal layer outside the reinforcing layer.

12. When an X-axis, a Y-axis orthogonal to the X-axis, and a Z-axis perpendicular to the X-Y plane are defined, a method for manufacturing a graphite composite including anisotropic graphite in which the crystal orientation plane of the graphite layer is arranged parallel to the X-Z plane, and having a first main surface parallel to the X-Y plane and a second main surface facing the first main surface, the method comprising: a reinforcing step of forming a reinforcing layer on at least one surface of the anisotropic graphite parallel to the Y-Z plane, the reinforcing step of bonding the anisotropic graphite and the reinforcing layer via an adhesive layer; and a metal layer forming step of forming a first metal layer and a second metal layer on the first main surface and the second main surface of the anisotropic graphite on which the reinforcing layer is formed, wherein the thicknesses of the first metal layer and the second metal layer are 2 μm to 50 μm, and the adhesive layer contains a resin, the method for manufacturing a graphite composite.

13. The method for manufacturing a graphite composite according to claim 12, further comprising a cutting step of cutting the reinforcing layer and the anisotropic graphite after the reinforcing step.

14. The method for manufacturing a graphite composite according to claim 12, wherein the resin contained in the adhesive layer is at least one selected from the group consisting of an acrylic resin, a silicone resin, and an epoxy resin.

15. The method for manufacturing a graphite composite according to claim 12, wherein in the metal layer forming step, the first metal layer and the second metal layer are formed simultaneously.

16. The method for manufacturing a graphite composite according to claim 12, wherein in the metal layer forming step, a third metal layer and a fourth metal layer are further formed on both surfaces of the outermost layer of the anisotropic graphite parallel to the X-Z plane.

17. The method for manufacturing a graphite composite according to claim 16, wherein in the metal layer forming step, a fifth metal layer is further formed outside the reinforcing layer.

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