Anisotropic graphite composite and its manufacturing method

Abstract

The present invention addresses the problem of providing an anisotropic graphite composite excellent in heat transfer efficiency. The problem is solved by an anisotropic graphite composite (100), in which: (a) anisotropic graphite (10), which comprises a graphite layer having a crystal orientation plane (11) arranged parallel to an X-Y plane, and (b) an adhesive layer (20), which contains a metal and / or a resin, are alternately laminated in the Z-axis direction and are bonded to each other; and a thermal resistance value, measured on a surface parallel to the X-Z plane or the Y-Z plane of the composite (100), is 10 mm2 K / W or less.

Description

[Technical Field]

[0001] The present invention relates to an anisotropic graphite composite and a method for producing the same. [Background technology]

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

[0003] In particular, anisotropic graphite, which has a graphite structure in which six-membered rings are connected by covalent bonds and each graphite structure is bonded by van der Waals forces, has high thermal conductivity. Anisotropic graphite is useful as a heat transfer element that suppresses hot spots that occur in electronic devices and electronic components, which are heat sources, and efficiently transfers heat from the heat source to a cooler.

[0004] Furthermore, anisotropic graphite is structurally brittle and prone to crumbling. To solve this strength issue, a technique has been proposed in which an anisotropic graphite composite formed by laminating anisotropic graphite with layers made of metal, resin, etc. is used as a heat transfer element. For example, Patent Document 1 proposes a technique in which an inorganic material layer is formed on the surface of anisotropic graphite. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 5930604 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-described conventional anisotropic graphite composites have room for improvement in terms of heat transfer efficiency.

[0007] In view of the above circumstances, an object of one aspect of the present invention is to provide an anisotropic graphite composite having excellent heat transfer efficiency and a method for producing the same. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have completed the present invention. That is, one embodiment of the present invention is a graphite composite including (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, wherein an X axis, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the XY plane are defined, and the crystal orientation plane of the graphite layer in the anisotropic graphite is arranged parallel to the XY plane, and (a) the anisotropic graphite and (b) the adhesive layer containing a metal and / or a resin are alternately stacked in the Z axis direction and bonded to each other, and the thermal resistance value measured on a surface of the composite parallel to the XZ plane or the YZ plane is 10 mm 2 It is an anisotropic graphite composite with a K / W or less.

[0009] Another embodiment of the present invention is a method for producing an anisotropic graphite composite including (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, wherein an X axis, a Y axis orthogonal to the X axis, and a Z axis perpendicular to the XY plane are defined, and the crystal orientation plane of the graphite layer in the anisotropic graphite is oriented parallel to the XZ plane, the method comprising: a bonding step of alternately stacking and bonding the (a) anisotropic graphite and the (b) adhesive layer containing a metal and / or a resin in the Z axis direction; a cutting step of cutting the resulting bonded body; and a surface peeling step of peeling off a surface parallel to the XZ plane or the YZ plane of the bonded body obtained in the cutting step after cutting. [Effects of the Invention]

[0010] According to one embodiment of the present invention, it is possible to provide an anisotropic graphite composite having excellent heat transfer performance and long-term reliability as a heat transfer element, and a method for manufacturing the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a general configuration of an anisotropic graphite composite according to one embodiment of the present invention. [Figure 2] FIG. 1 shows images of the surfaces of anisotropic graphite composites according to examples of the present invention and comparative examples, observed with a scanning electron microscope (SEM). [Figure 3] FIG. 10 is a diagram showing an image of a cross section of a joined body of anisotropic graphite according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] One 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 appropriately 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. Anisotropic graphite composite] An anisotropic graphite composite according to one embodiment of the present invention (hereinafter, may be referred to as "the composite") is a graphite composite including (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, wherein an X axis, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the XY plane are defined, and the crystal orientation plane of the graphite layer in the anisotropic graphite is arranged parallel to the XY plane, and (a) the anisotropic graphite and (b) the adhesive layer containing a metal and / or a resin are alternately stacked in the Z axis direction and bonded to each other, and the thermal resistance value measured on a surface of the composite parallel to the XZ plane or the YZ plane is 10 mm 2 K / W or less.

[0014] The composite has the above-described structure and therefore has excellent heat transfer efficiency.

[0015] <1-1. Structure of anisotropic graphite composite> The structure of this composite will be described in detail with reference to Fig. 1. Fig. 1 is a schematic diagram showing the general configuration of this composite. As shown in Fig. 1, this composite 100 includes (a) anisotropic graphite 10 and (b) adhesive layer 20 containing a metal and / or resin. When an X axis, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the XY plane are defined, crystal orientation plane 11 of the graphite layer in (a) anisotropic graphite 10 is arranged parallel to the XY plane, and (a) anisotropic graphite 10 and (b) adhesive layer 20 containing a metal and / or resin are alternately stacked in the Z axis direction and bonded to each other.

[0016] (thickness of anisotropic graphite composite) The thickness of the composite is not particularly limited, but is preferably 1 mm or less, and more preferably 0.5 mm or less. By controlling the thickness of the composite to 1 mm or less, an anisotropic graphite composite with superior heat transfer efficiency can be provided. The lower limit of the thickness of the composite is not particularly limited, but may be, for example, 0.01 mm or more. In this specification, the thickness of the composite refers to the thickness in the direction perpendicular to the cut surface formed in the cutting step described below (for example, when a cut surface parallel to the XZ plane is formed, it is the thickness in the Y-axis direction, and when a cut surface parallel to the YZ plane is formed, it is the thickness in the X-axis direction).

[0017] The thickness of the (a) anisotropic graphite in the Z-axis direction (the thickness of each layer of the (a) anisotropic graphite) in the composite is not particularly limited, but is preferably 10 μm to 1 mm from the viewpoint of providing a composite with better heat transfer efficiency, more preferably 50 μm to 500 μm, and even more preferably 50 μm to 300 μm.

[0018] The thickness in the Z-axis direction of the (b) metal and / or resin-containing adhesive layer in this composite (thickness per layer of the (b) metal and / or resin-containing adhesive layer) is not particularly limited, but is preferably 0.1 μm to 1 mm from the viewpoint of providing a composite with better heat transfer efficiency, more preferably 0.5 μm to 300 μm, and even more preferably 1.0 μm to 150 μm or less.

[0019] <1-2.(a) Anisotropic graphite> The composite contains (a) anisotropic graphite. In this specification, anisotropic graphite has a block-like structure in which many layers (in other words, graphite layers) having a graphite structure in which six-membered carbon rings are connected by covalent bonds are stacked. The block-like (a) anisotropic graphite has high thermal conductivity in a direction parallel to the crystal orientation plane of the graphite layer. The "anisotropy" of anisotropic graphite means that, due to the orientation of the graphite layers, the thermal conductivity of the anisotropic graphite differs greatly in the directions parallel to and perpendicular to the crystal orientation plane of the graphite layer.

[0020] Anisotropic graphite (a) according to one embodiment of the present invention has a block-like shape in which many layers (i.e., graphite layers) having a graphite structure in which six-membered rings are connected by covalent bonds are stacked. The anisotropic graphite (a) in the block shape has high thermal conductivity in a direction parallel to the crystal orientation plane of the graphite layers.

[0021] The type of anisotropic graphite (a) according to one embodiment of the present invention is not particularly limited as long as it has high thermal conductivity in the plane direction of the graphite structure in which six-membered rings are connected by covalent bonds. Specifically, examples of anisotropic graphite (a) that can be used include polymer-decomposed anisotropic graphite obtained by decomposing (e.g., pyrolyzing) a polymer, graphene oxide, HOPG (Highly Oriented Pyrolytic Graphite), pyrolytic anisotropic graphite obtained by heat-treating Kish graphite, extruded anisotropic graphite obtained by extruding expanded graphite, and molded anisotropic graphite obtained by molding expanded graphite. (a) Anisotropic graphite has high thermal conductivity in the plane direction of the graphite structure in which six-membered rings are connected by covalent bonds, and anisotropic graphite composites containing (a) anisotropic graphite have superior heat transfer performance. Therefore, it is preferable to use polymer-decomposed anisotropic graphite or pyrolytic anisotropic graphite as the (a) anisotropic graphite, and it is more preferable to use polymer-decomposed anisotropic graphite.

[0022] (Method for producing anisotropic graphite) The method for producing (a) anisotropic graphite according to one embodiment of the present invention is not particularly limited, and may, for example, be a so-called polymer pyrolysis method in which a polymer film (e.g., a polyimide film) is heat-treated in an inert gas atmosphere or under reduced pressure. Such a polymer pyrolysis method makes it possible to produce polymer-decomposed anisotropic graphite. A more specific example of a method for producing (a) anisotropic graphite using a polymer pyrolysis method includes a carbonization step in which a polymer film (e.g., a polyimide film) is heat-treated at a temperature of about 1400°C to obtain a carbonaceous film, a graphitization step in which the carbonaceous film obtained in the carbonization step is heat-treated at a temperature of about 2900°C to graphitize it, thereby obtaining a film-like anisotropic graphite, and a rolling step in which the obtained film-like anisotropic graphite is rolled.

[0023] (carbonization process) (a) The carbonization step in the method for producing anisotropic graphite is a step in which a polymer film is heat-treated at a temperature of about 1400° C. to carbonize it. The carbonization step is preferably carried out in a vacuum atmosphere, under reduced pressure, or in an inert gas, and nitrogen is preferably used as the inert gas.

[0024] The temperature (maximum temperature) at which the polymer film is heat-treated in the carbonization step is, for example, preferably 1200°C to 1600°C, and more preferably 1300°C to 1500°C.

[0025] (Graphitization process) (a) The graphitization process of anisotropic graphite is a process in which the carbonaceous film obtained in the carbonization process is heat-treated at a temperature of about 2900° C. The graphitization process is preferably carried out under reduced pressure or in an inert gas, and argon or helium can be suitably used as the inert gas, with argon containing a small amount of helium being more suitably used.

[0026] In the graphitization step, the temperature (maximum temperature) at which the carbonaceous film obtained in the carbonization step is heat-treated is, for example, preferably 2400° C. or higher, preferably 2600° C. or higher, preferably 2800° C. or higher, preferably 2900° C. or higher, or preferably 3000° C. or higher. There is no particular limitation on the upper limit of the maximum temperature, but it is preferably 3300° C. or lower, and more preferably 3200° C. or lower.

[0027] (Rolling process) (a) The rolling step in the method for producing anisotropic graphite is a step of rolling the film of anisotropic graphite obtained in the graphitization step. In this specification, the film of anisotropic graphite obtained in the graphitization step and before being subjected to the rolling step may be referred to as the anisotropic graphite film before rolling, and the film of anisotropic graphite after being subjected to the rolling step may be referred to as the anisotropic graphite film after rolling.

[0028] In the rolling step, the method for rolling the anisotropic graphite film is not particularly limited, and examples thereof include a method of applying pressure using a single plate press or a roll press.

[0029] <1-3.(b) Adhesive layer containing metal and / or resin> The composite includes (b) an adhesive layer containing a metal and / or a resin. In this specification, the "(b) adhesive layer containing a metal and / or a resin" may be referred to as the "(b) adhesive layer."

[0030] (b) The adhesive layer may contain only a metal, may contain only a resin, or may contain both a metal and a resin.

[0031] The metal that can be contained in the (b) adhesive layer is not particularly limited, but is preferably one or more selected from nickel, titanium, iron, chromium, tungsten, and stainless steel, as these metals are partially compatible with graphite at high temperatures and have good adhesive properties. Among these, nickel is particularly preferred as the metal contained in the (b) adhesive layer, as it has strong adhesive strength and excellent heat transfer performance.

[0032] (b) The resin that can be contained in the adhesive layer is not particularly limited, but is preferably one or more resins selected from acrylic resins, silicone resins, urethane resins, polyimide resins, polyamideimide resins, and epoxy resins, because they have the advantage of easily adhering to graphite.

[0033] <1-4. Physical properties of anisotropic graphite composites> (thermal resistance value) The thermal resistance of this composite is 10mm 2 K / W or less. The thermal resistance of the anisotropic graphite composite is 10 mm 2 K / W or less means that the composite has excellent heat transfer efficiency. The method for measuring the thermal resistance of the anisotropic graphite composite in this specification is as described in the Examples.

[0034] The thermal resistance of this composite is 10mm 2 There is no particular limitation as long as the heat transfer efficiency is 9 mm / W or less. However, from the viewpoint of providing a composite having a better heat transfer efficiency, 2 K / W or less is preferable, and 8 mm 2 K / W or less is more preferable, and 7 mm 2 K / W or less is more preferable, and 6.5 mm 2 The lower limit of the thermal resistance of the composite is particularly preferably 1 mm 2 It can be more than K / W.

[0035] 2. Method for producing anisotropic graphite composite A method for producing an anisotropic graphite composite according to one embodiment of the present invention (hereinafter, sometimes referred to as "this production method") will be described. This production method is a method for producing a composite of anisotropic graphite including (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, where the X axis, the Y axis perpendicular to the X axis, and the Z axis perpendicular to the XY plane are defined, and the crystal orientation plane of the graphite layer in the anisotropic graphite is parallel to the XY plane, and the method includes the following steps: a bonding step of alternately stacking and bonding (a) anisotropic graphite and (b) adhesive layers containing a metal and / or a resin in the Z axis direction; a cutting step of cutting the resulting bonded body; and a surface peeling step of peeling off the surface of the bonded body obtained in the cutting step that is parallel to the XZ plane or the YZ plane.

[0036] Specific embodiments of (a) anisotropic graphite and (b) adhesive layer containing a metal and / or a resin used in this production method are as described above in the section [1. Anisotropic graphite composite].

[0037] <2-1. Adhesion process> This manufacturing method includes a bonding step in which (a) anisotropic graphite and (b) adhesive layers containing a metal and / or a resin are alternately stacked in the Z-axis direction and bonded together. The bonding step can also be said to be a step of obtaining a bonded body of anisotropic graphite to be subjected to the cutting step, in other words, a bonded body before cutting.

[0038] In the bonding step, there is no particular limitation on the method for bonding a laminate (hereinafter sometimes simply referred to as a "laminate") formed by alternately stacking (a) anisotropic graphite and (b) adhesive layers containing a metal and / or resin in the Z-axis direction. However, a method of applying a load to the laminate to apply pressure along the Z-axis direction and heating the laminate (hereinafter referred to as "Method A") can be suitably applied.

[0039] (Lamination method) In method A, when a metal forming an adhesive layer containing a (b) metal and / or a resin is laminated on an anisotropic graphite (a), the metal can be laminated by (i) directly laminating the metal on the anisotropic graphite (a). More specifically, the metal may be laminated on the anisotropic graphite (a) by a coating method, a vacuum deposition method, a CVD method, a sputter deposition method, or the like, or a sheet-shaped metal sheet may be laminated on the anisotropic graphite (a).

[0040] Furthermore, in method A, when (b) a resin forming an adhesive layer containing a metal and / or a resin is laminated with (a) anisotropic graphite, the resin may be laminated by applying it to (a) anisotropic graphite, or a sheet-shaped resin sheet may be laminated.

[0041] (pressure) In Method A, the pressure to be applied to the laminate is not particularly limited as long as it can bond (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or resin. For example, the pressure may be 0.05 to 10 kg / cm. 2 It is preferable to apply pressure to the laminate with a load of 0.1 to 5 kg / cm 2 It is more preferable to pressurize the laminate with a load of 1000 kJ / cm.sup.2 or more. Pressurizing with the above pressure can provide an anisotropic graphite composite having excellent adhesive strength between the anisotropic graphite particles.

[0042] (heating) In Method A, the laminate is preferably heated in a vacuum, in an inert gas such as nitrogen and / or argon, in a reducing gas such as hydrogen, or in a mixed gas of an inert gas and a reducing gas. In particular, heating in Method A is preferably performed in an inert gas, because this allows the laminate to be produced without destroying the crystal structure of the anisotropic graphite, thereby providing an anisotropic graphite composite with excellent thermal conductivity.

[0043] In Method A, the temperature to which the laminate is heated is not particularly limited, but is preferably 700 to 1700° C., and more preferably 1000 to 1600° C. Heating at the above temperatures can provide an anisotropic graphite composite having excellent adhesive strength between the anisotropic graphite particles.

[0044] <2-2. Cutting process> This manufacturing method includes a cutting step of cutting the bonded body obtained in the bonding step before cutting. The cutting step can also be considered a step of obtaining a cut bonded body, which is a bonded body of anisotropic graphite that is subjected to the surface peeling step. The cutting step can also be considered a step of cutting the bonded body along a plane parallel to the XZ plane or YZ plane of the bonded body (i.e., so that a cut surface parallel to the XZ plane or YZ plane is formed) so that the thickness of the cut bonded body in a direction perpendicular to the XZ plane or YZ plane (in other words, perpendicular to the cut surface) becomes a desired thickness.

[0045] In the cutting step, the method for cutting the bonded body before cutting is not particularly limited, and any known technique such as a diamond cutter, a wire saw, or machining can be appropriately selected. In particular, it is preferable to cut the bonded body before cutting using a wire saw in the cutting step, since this makes it easy to provide a thinner (thin film) bonded body and an anisotropic graphite composite.

[0046] When the bonded body before cutting is cut using a wire saw in the cutting step, it is preferable to cut the bonded body before cutting under conditions of a cutting speed of 1.0 mm / min or less and 0.01 mm / min or more, and more preferably under conditions of a cutting speed of 0.5 mm / min or less and 0.01 mm / min or more, because this reduces the formation of saw marks (irregularities) on the cut surface (surface parallel to the XZ plane or YZ plane) of the bonded body after cutting and makes the cut surface smoother, thereby providing an anisotropic graphite composite with better heat transfer efficiency.

[0047] <2-3. Surface peeling process> This manufacturing method includes a surface peeling step of peeling a surface parallel to the XZ plane or the YZ plane of the cut bonded body obtained in the cutting step. Here, the surface parallel to the XZ plane or the YZ plane of the cut bonded body refers to the surface (cut surface) of the bonded body cut in the cutting step. The surface peeling step can also be said to be a step of obtaining a surface-peeled anisotropic graphite composite. The "anisotropic graphite composite" obtained by this manufacturing method refers to this surface-peeled anisotropic graphite composite.

[0048] In the surface peeling step, the method for peeling the surface of the bonded body after cutting is not particularly limited, but an example is a method in which an easily peelable adhesive tape is adhered to the surface of the anisotropic graphite composite before surface peeling (a surface parallel to the XZ plane or the YZ plane) and then the adhesive tape is peeled off. The adhesive tape that can be used in this method is not particularly limited, and any common adhesive tape can be used, but suitable examples include mending tape manufactured by 3M that has an acrylic adhesive layer, and polyimide tape that has a silicone adhesive layer.

[0049] In the course of intensive research to provide an anisotropic graphite composite with excellent heat transfer efficiency, the present inventors discovered that in a conventional anisotropic graphite composite (manufactured without a surface exfoliation step), on the XZ or YZ plane surface that comes into contact with a heat source, (i) the edges of each graphite layer forming the anisotropic graphite composite present on the surface are covered with fine deposits, and (ii) the edges are oriented in a direction approximately parallel to the XZ or YZ plane. The present inventors believed that the above (i) and (ii) reduced the heat transfer efficiency of conventional anisotropic graphite composites, and conducted further intensive research to provide an anisotropic graphite composite that does not suffer from the above (i) and (ii). As a result, the inventors have found that by further carrying out a surface peeling step after the cutting step, (I) fine deposits present on the surface of the anisotropic graphite composite before the surface peeling can be removed, and (II) an anisotropic graphite composite can be provided in which the edges of each graphite layer forming the anisotropic graphite composite are oriented in a substantially vertical direction, and that this anisotropic graphite composite after the surface peeling has excellent heat transfer efficiency, thereby completing the present invention.

[0050] In other words, the anisotropic graphite composite (present composite) obtained by the present production method can be said to be an anisotropic graphite composite in which (I) there are almost no fine deposits on the surface in the XZ plane or the YZ plane, and (II) the ends of each graphite layer forming the anisotropic graphite composite are oriented in a substantially vertical direction.

[0051] The state of the edges of each graphite layer forming the anisotropic graphite composite can be observed using, for example, a scanning electron microscope (SEM).

[0052] [3. Other] An embodiment of the present invention may include the following configuration.

[0053] [1] A graphite composite comprising (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, the composite having an X axis, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the XY plane, the crystal orientation plane of the graphite layer in the anisotropic graphite being arranged parallel to the XY plane, the anisotropic graphite and the adhesive layer containing a metal and / or a resin being alternately stacked in the Z axis direction and bonded to each other, and the thermal resistance value measured on a surface of the composite parallel to the XZ plane or the YZ plane is 10 mm 2 K / W or less, anisotropic graphite composite.

[0054] [2] The anisotropic graphite composite according to [1], wherein the metal is at least one selected from the group consisting of nickel, titanium, iron, chromium, tungsten, and stainless steel.

[0055] [3] The anisotropic graphite composite according to [1], wherein the resin is at least one selected from the group consisting of acrylic resin, silicone resin, urethane resin, polyimide resin, polyamide-imide resin, and epoxy resin.

[0056] [4] The thermal resistance value is 8 mm 2 The anisotropic graphite composite according to any one of [1] to [3], wherein the anisotropic graphite composite has a viscosity of 1000 kJ / W or less.

[0057] [5] The anisotropic graphite composite according to any one of [1] to [4], wherein the anisotropic graphite (a) is polymer-decomposed anisotropic graphite or pyrolytic anisotropic graphite.

[0058] [6] A method for producing an anisotropic graphite composite including (a) anisotropic graphite and (b) an adhesive layer containing a metal and / or a resin, wherein an X axis, a Y axis perpendicular to the X axis, and a Z axis perpendicular to the XY plane are defined, and the crystal orientation plane of the graphite layer in the anisotropic graphite is arranged parallel to the XZ plane, the method comprising: a bonding step of alternately stacking and bonding (a) anisotropic graphite and (b) the adhesive layer containing a metal and / or a resin in the Z axis direction; a cutting step of cutting the resulting bonded body; and a surface peeling step of peeling off a surface parallel to the XZ plane or the YZ plane of the bonded body obtained in the cutting step after cutting.

[0059] [7] The method for producing an anisotropic graphite composite according to [6], wherein the cutting step includes cutting the anisotropic graphite composite using a wire saw at a cutting speed of 1.0 mm / min or less.

[0060] [8] The method for producing an anisotropic graphite composite according to [6] or [7], wherein the metal is at least one selected from nickel, titanium, iron, chromium, tungsten, and stainless steel.

[0061] [9] The method for producing an anisotropic graphite composite according to any one of [6] to [8], wherein the resin is at least one selected from an acrylic resin, a silicone resin, a urethane resin, a polyimide resin, a polyamide-imide resin, and an epoxy resin.

[0062]

[10] The method for producing an anisotropic graphite composite according to any one of [6] to [9], wherein the anisotropic graphite (a) is polymer-decomposed anisotropic graphite or pyrolytic anisotropic graphite. [Example]

[0063] Hereinafter, one embodiment of the present invention will be described in detail with reference to examples and comparative examples, but the technical scope of the present invention is not limited to these examples.

[0064] [Method for measuring thermal resistance] The thermal resistance of each composite and adhesive bond obtained in the Examples and Comparative Examples was measured as follows: A sample measuring 10 mm long x 10 mm wide was cut from the composite or adhesive bond obtained, having any thickness. The thermal resistance (thickness direction thermal resistance of the composite or adhesive bond) of the obtained sample was measured using a resin thermal resistance measuring device (manufactured by Hitachi Technology and Services Co., Ltd.) by clamping the sample between probes at a sample temperature of 50°C and a constant load of 20 N.

[0065] Example 1 A 75 μm thick polyimide film (Apical NPI manufactured by Kaneka) measuring 250 mm length × 310 mm width and a 200 μm thick natural graphite sheet measuring 260 mm length × 320 mm width were alternately laminated in 100 sheets each to obtain a 27.5 mm thick laminate. A graphite weight was placed on the obtained laminate, and a 5 g / cm 2 The polyimide film was carbonized by heating it to 1400°C at a heating rate of 0.5°C / min and holding it at 1400°C for 10 minutes, thereby obtaining a carbonized film.

[0066] Next, the obtained carbonized film was laminated again with 100 natural graphite sheets, each 200 μm thick and 260 mm long x 320 mm wide, to obtain a laminate with a thickness of 27.5 mm. A graphite weight was placed on the obtained laminate, and a weight of 5 g / cm was applied. 2 The carbonized film was graphitized by placing it in a graphitization furnace under a load of 1000 kJ / min, raising the temperature to 2900°C at a heating rate of 3.3°C / min, and holding it at 2900°C for 10 minutes, thereby obtaining an anisotropic graphite film.

[0067] One hundred of the obtained anisotropic graphite films (thickness: 300 μm) were stacked, and the stack was sandwiched between a polyimide film, a Teflon (registered trademark) film, a cushioning rubber material, and an iron plate on the top and bottom. The stack was then rolled using a single-plate press at room temperature under a pressure of 20 MPa to obtain a rolled anisotropic graphite film (thickness: 200 μm).

[0068] The rolled anisotropic graphite film was cut into 400 sheets measuring 40 mm long x 40 mm wide. These 400 anisotropic graphite films were alternately stacked with 399 sheets of nickel foil, each 5 μm thick and 40 mm long x 40 mm wide, to obtain a laminate. This laminate was heated in argon gas at 0.4 kg / cm 2 While applying a pressure of 1000 kJ / s, the temperature was raised to 1340°C at a heating rate of 2.0°C / min and held at 1340°C for 30 minutes to bond the anisotropic graphite film and nickel foil by heat fusion, producing an anisotropic graphite / nickel bonded body A-1 (thickness: 60 mm, size: length 40 mm × width 40 mm) in which adhesive layers made of anisotropic graphite and nickel were alternately laminated. For the obtained bonded body A-1, the plane parallel to the crystal orientation plane of the graphite layer of the anisotropic graphite was defined as the XY plane, and the thickness direction was defined as the Z axis.

[0069] The obtained bonded body A was cut in a direction parallel to the Y-Z plane using a wire saw (Takatori Corporation, Model WSD-K2) at a cutting speed of 0.5 mm / min to obtain an anisotropic graphite / nickel bonded body B-1 (bonded body after cutting) with a thickness of 0.25 mm (X axis) and a size of 40 mm (Y axis) x 60 mm (Z axis) (cutting step). Furthermore, this bonded body B-1 was cut into samples with a thickness of 0.25 mm (X axis) and a size of 10 mm (Y axis) x 10 mm (Z axis). The thermal resistance value (thermal resistance value in the X axis direction) of the obtained bonded body B-1 sample was measured, and the thermal resistance value was 10.8 mm. 2 The surface of the bonded body B-1 parallel to the YZ plane was observed using a scanning electron microscope (SEM). An image obtained by SEM at 500x magnification is shown in Figure 2 (top). As shown in Figure 2 (top), on the surface of the bonded body B-1 parallel to the YZ plane, the edges of the graphite forming each graphite layer were covered with fine deposits, and further, these edges were oriented in a direction approximately parallel to the YZ plane.

[0070] For the sample of the above-mentioned bonded body B-1, mending tape (manufactured by 3M) was attached to both surfaces parallel to the YZ plane and then carefully peeled off to obtain an anisotropic graphite / nickel composite C-1 (graphite composite after surface peeling) (surface peeling step). The thermal resistance value (thermal resistance value in the X-axis direction) of the obtained composite C-1 was measured, and the thermal resistance value was 5.7 mm. 2 The surface of composite C-1 parallel to the YZ plane was observed using a scanning electron microscope (SEM). An image obtained by SEM at 500x magnification is shown in Figure 2 (lower). As shown in Figure 2 (lower), on the surface of composite C-1 parallel to the YZ plane, the ends of the graphite particles forming each graphite layer were oriented in a direction approximately perpendicular to the YZ plane.

[0071] Example 2 The bonded body A-1 obtained in Example 1 was cut in a direction parallel to the Y-Z plane using a wire saw (Model WSD-K2, manufactured by Takatori Corporation) at a cutting speed of 0.5 mm / min to obtain an anisotropic graphite / nickel bonded body B-2 having a thickness of 0.30 mm (X axis) and a size of 40 mm (Y axis) x 60 mm (Z axis) (cutting step). Visual inspection of the cut surface of the obtained bonded body B-2 revealed no saw marks from the wire saw. Furthermore, this bonded body B-2 was cut into samples having a thickness of 0.30 mm (X axis) and a size of 10 mm (Y axis) x 10 mm (Z axis). The thermal resistance value (thermal resistance value in the X axis direction) of the obtained bonded body B-2 sample was measured, and the thermal resistance value was 15.0 mm. 2 It was K / W.

[0072] For the sample of the above-mentioned bonded body B-2, mending tape (manufactured by 3M) was attached to both surfaces parallel to the YZ plane and then carefully peeled off to obtain an anisotropic graphite / nickel composite C-2 (graphite composite after surface peeling) (surface peeling step). The thermal resistance value (thermal resistance value in the X-axis direction) of the obtained composite C-2 was measured, and the thermal resistance value was 6.2 mm. 2The results are shown in Table 1. The surface of composite C-2 parallel to the YZ plane was also observed using a scanning electron microscope (SEM). On the surface of composite C-2 parallel to the YZ plane, the ends of the graphite particles forming each graphite layer were oriented in a direction approximately perpendicular to the YZ plane (not shown).

[0073] (Comparative Example 1) The bonded body A-1 obtained in Example 1 was cut at a perpendicular angle to the X-axis using a wire saw (Model WSD-K2, manufactured by Takatori Corporation) at a cutting speed of 1.5 mm / min to obtain an anisotropic graphite / nickel bonded body B-3 having a thickness of 0.40 mm (X-axis) and a size of 40 mm (Y-axis) x 60 mm (Z-axis). The cut surface of the obtained bonded body B-3 was visually inspected, and the results are shown in Figure 3. As shown in Figure 3, saw marks from the wire saw were observed on the cut surface of the bonded body B-3. Furthermore, this bonded body B-3 was cut into samples having a thickness of 0.40 mm (X-axis) and a size of 10 mm (Y-axis) x 10 mm (Z-axis). The thermal resistance value (thermal resistance value in the X-axis direction) of the obtained bonded body B-3 sample was measured, and the thermal resistance value was 24.6 mm. 2 It was K / W.

[0074] 〔summary〕 The composites of Examples 1 and 2 obtained through the cutting process and the surface peeling process both had a thermal resistance of 10 mm 2 K / W or less, which indicates that the composite has excellent heat transfer performance. On the other hand, Comparative Example 1 indicates that the heat transfer performance of the composite obtained is poor when the surface peeling step is not performed. [Industrial Applicability]

[0075] According to one embodiment of the present invention, an anisotropic graphite composite having excellent heat transfer efficiency can be provided. Such an anisotropic graphite composite can be suitably used in fields such as electronic devices and electronic components. [Explanation of symbols]

[0076] 10 Anisotropic graphite 11 Crystal orientation of graphite layers in anisotropic graphite 20 Adhesive layer 100 Anisotropic graphite composite

Claims

1. An anisotropic graphite composite comprising: (a) anisotropic graphite; and (b) an adhesive layer comprising a metal and / or a resin, The X axis, the Y axis perpendicular to the X axis, and the Z axis perpendicular to the XY plane, (a) the crystal orientation plane of the graphite layer in the anisotropic graphite is arranged parallel to the XY plane; the (a) anisotropic graphite and the (b) adhesive layer containing a metal and / or a resin are alternately stacked in the Z-axis direction and adhered to each other; The thermal resistance value measured on a surface of the anisotropic graphite composite parallel to the XZ plane or the YZ plane is 10 mm ２ K / W or less of anisotropic graphite composite.

2. The adhesive layer contains a metal or a metal and a resin, 2. The anisotropic graphite composite according to claim 1, wherein the metal is at least one selected from the group consisting of nickel, titanium, iron, chromium, tungsten, and stainless steel.

3. The adhesive layer comprises a resin or a metal and a resin, 2. The anisotropic graphite composite according to claim 1, wherein the resin is at least one selected from the group consisting of an acrylic resin, a silicone resin, a urethane resin, a polyimide resin, a polyamide-imide resin, and an epoxy resin.

4. The thermal resistance value is 8 mm ２ 2. The anisotropic graphite composite of claim 1, wherein the anisotropic graphite composite has a viscosity of 1000 kJ / s or less.

5. 2. The anisotropic graphite composite according to claim 1, wherein the anisotropic graphite (a) is polymer-decomposed anisotropic graphite or pyrolytic anisotropic graphite.

6. 1. A method for producing an anisotropic graphite composite, comprising: (a) anisotropic graphite; and (b) an adhesive layer comprising a metal and / or a resin, the method comprising: The X axis, the Y axis perpendicular to the X axis, and the Z axis perpendicular to the XY plane, (a) the crystal orientation plane of the graphite layer in the anisotropic graphite is arranged parallel to the XY plane; a bonding step of alternately stacking and bonding the (a) anisotropic graphite and the (b) adhesive layer containing a metal and / or a resin in the Z-axis direction; a cutting step of cutting the bonded body obtained in the bonding step; a surface peeling step of peeling off a surface parallel to the XZ plane or the YZ plane of the bonded body after cutting obtained in the cutting step.

7. The cutting step includes:

7. The method for producing an anisotropic graphite composite according to claim 6, further comprising the step of cutting the bonded body using a wire saw at a cutting speed of 1.0 mm / min or less.

8. The adhesive layer contains a metal or a metal and a resin, 7. The method for producing an anisotropic graphite composite according to claim 6, wherein the metal is at least one selected from the group consisting of nickel, titanium, iron, chromium, tungsten, and stainless steel.

9. The adhesive layer comprises a resin or a metal and a resin, 7. The method for producing an anisotropic graphite composite according to claim 6, wherein the resin is at least one selected from the group consisting of an acrylic resin, a silicone resin, a urethane resin, a polyimide resin, a polyamide-imide resin, and an epoxy resin.

10. 7. The method for producing an anisotropic graphite composite according to claim 6, wherein the anisotropic graphite (a) is polymer-decomposed anisotropic graphite or pyrolytic anisotropic graphite.

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