JP2005272164A - High thermal conductive member, method of manufacturing the same and heat radiation system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high thermal conductive member having thermal conductivity improved in the layer direction and enhanced tensile strength while keeping thermal conductive characteristic in the plane direction which graphite has. <P>SOLUTION: The high thermal conductive member comprises carbon (C) as main composition and has the efficient thermal conductive characteristic in the layer direction because a carbon structure 3 comprising a carbon fiber assembled body is arranged in a graphite structure 1 having an a-b axis almost aligned in the direction (plane direction) parallel to the main surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a highly thermally conductive member whose main composition is carbon (C) and a method for producing the same. Specifically, to improve the characteristics of the thermal conductive member made of a graphite structure having anisotropy in thermal conductivity, while maintaining high thermal conductivity in the direction parallel to the main surface (plane direction), The present invention relates to a highly thermally conductive member having a relatively high thermal conductivity in a direction (layer direction) perpendicular to a main surface and having a high degree of design freedom of a member such as thickness and tensile strength, and a method for manufacturing the same.

  2. Description of the Related Art In recent years, with the performance enhancement, miniaturization, and densification of electronic devices, it has become a problem how to dissipate heat generated from the devices and the electronic devices that constitute them. In particular, heat countermeasures for CPUs and semiconductor lasers, which are the heart of computers, are in an urgent need.

  In order to efficiently perform cooling, it is important to combine convection, radiation, and conduction well. However, in order to cool the electronic components, etc., it is mainly necessary to conduct heat to a low temperature region and cool it by heat conduction. It is valid.

  Conventionally, as a heat dissipation method for electronic devices / components, a heat radiator made of a metal having high thermal conductivity, such as copper (Cu) or aluminum (Al), has been often used. However, as device miniaturization and further heat generation increase, high thermal conductivity members with higher thermal conductivity and higher geometric shape are desired. Further, if the thickness and tensile strength are increased, it becomes an ideal high thermal conductive member.

  Against such a background, graphite made of carbon (C) has excellent heat resistance, chemical resistance, high conductivity, and also has characteristics such as high thermal conductivity. Expected.

  Graphite is a material having a crystal structure as shown in FIG. 3, and has a structure in which a six-membered planar structure (graphene structure) 5 composed of carbon (C) atoms 4 is laminated in layers. From this crystal structure, various characteristics of graphite are characterized by two directions, that is, a direction perpendicular to the graphene structure 5 (c-axis direction) and a direction parallel to the graphene structure 5 (ab-axis direction). Is suggested.

  For example, in an ideal graphite crystal, the thermal conductivity κ⊥ of the plane perpendicular to the graphene structure 5 (c-axis direction, hereinafter referred to as “layer direction”) is not so high as 10 W / m · K or less. The thermal conductivity κ‖ of the plane parallel to structure 5 (ab-axis direction, hereinafter referred to as “plane direction”) exceeds 1000 W / m · K, and copper (κ (Cu) to 350-400 W / m · K) It has been reported that it has a thermal conductivity more than twice that of aluminum and more than four times that of aluminum (κ (Al) to 200-250 W / m · K). Therefore, various graphite thermal conductors have been proposed so far, taking advantage of the high thermal conductivity in the plane direction.

  For example, Patent Documents 1 to 4 and the like report a heat conducting member that has improved heat conduction characteristics by dispersing graphite powder in a silicone resin or a polymer matrix. FIG. 9 shows a schematic configuration image of a conventional heat conductive member (conventional example 1) disclosed therein. In Conventional Example 1, the thermal conductivity (κ to several tens of W / m · K) of the member can be improved by dispersing / orienting the graphite powder 10 having a high surface direction thermal conductivity in the matrix 9 such as a polymer. Has been reported.

  Patent Document 5 reports a member obtained by compression molding flaky graphite particles together with a polymer binder, and Patent Document 6 reports a member obtained by hot pressing a composite of metal powder and a crystalline carbon material. Has been. FIG. 10 shows a schematic configuration image of the conventional heat conductive member (conventional example 2) disclosed therein. In this conventional example 2, by compressing and molding graphite powder 12 having a high surface direction heat conductivity or a metal / graphite powder mixture, a heat conductive member 11 made of graphite having a high heat conductivity (κ‖ = 400˜ 970W / m · K) has been reported.

  Further, Patent Document 7 discloses a sheet-like heat conduction member made of a single graphite having high in-plane orientation. FIG. 11 shows a schematic configuration image of a conventional heat conductive member (conventional example 3) disclosed in this document. In Conventional Example 3, a thermally conductive member (κ‖ = 600 to 1000 W / m · K) made of a graphite structure 13 having a high in-plane orientation of the graphene layer 14 produced by a method of firing an organic polymer sheet. ) Has been reported.

As described above, the thermal conductive member using graphite as the thermal conductive material has points such as thermal conductivity and flexibility in shape as compared with the conventional member made of copper (Cu) or aluminum (Al). It has the characteristics of being excellent.
JP 09-283955 A JP 2002-299534 A JP 2002-363421 A JP 2003-105108 A JP-A-11-001621 JP-A-10-168502 Japanese Patent Application Laid-Open No. 07-109171 Japanese Patent Application Laid-Open No. 07-138838

  However, the conventional heat conductive member using graphite as shown in the conventional example has the following problems.

  In the configuration of Conventional Example 1 as shown in Patent Documents 1 to 4, since the graphite powder 10 having high thermal conductivity is certainly dispersed in the matrix 9, the thermal conductivity can be improved. There is a problem that it is difficult to obtain high thermal conductivity as a whole because the thermal conductivity of the matrix itself made of the resin or polymer constituting the material is low. That is, according to the reports so far, there is a problem that the thermal conductive member of about several tens of W / m · K is the limit, and it is insufficient for use in heat countermeasures that will be required in the future. Furthermore, since graphite is dispersed in a low thermal conductivity matrix to improve the thermal characteristics, it is essential to mix a relatively large amount of graphite powder with respect to the whole, so that there is a problem that the moldability is poor.

  Further, in the configuration of Conventional Example 2 as shown in Patent Document 5 or 6, since the member 11 is composed mainly of graphite powder 12 having high thermal conductivity, the thermal conductivity in the plane direction is improved. However, there is a problem that it is difficult to stably realize the high thermal conductivity inherent in graphite as a member because the influence and orientation of the contact heat resistance between particles are not sufficient. In addition, since the in-plane orientation of the graphite particles is made uniform by compression molding, there is a problem that it is difficult to improve the thermal conductivity in the layer direction. Further, in the conventional example 2, since it is generally necessary to compression-mold the powder body, there is a problem that it is difficult in terms of the degree of freedom of shape and ease of manufacture.

  Further, in the configuration of Conventional Example 3 shown in Patent Document 7, since it is composed of single crystal graphite having very high in-plane orientation, it has very high thermal conductivity in the plane direction. As described above, since the crystal structure of graphite has a remarkable anisotropy, there has been a problem that the thermal conductivity in the layer direction can be obtained only a few tenths of that. Therefore, it is a very high-performance heat conduction member for the purpose of transferring heat only in the direction of the member surface. However, in the future, the trend toward higher functionality / high density of equipment / devices will develop. There is a problem that improvement of heat conduction characteristics including the layer direction is necessary.

  Therefore, in order to solve the problems of the prior art, the present invention provides a high thermal conductivity member that improves the thermal conductivity in the layer direction while maintaining the high thermal conductivity in the plane direction of graphite, and the thickness of the member. The purpose is to increase the degree of freedom in design such as tensile strength.

  In order to solve the above-described conventional problems, the high thermal conductivity member of the present invention is a high thermal conductivity member whose main composition is carbon (C), and is a in a direction (plane direction) parallel to the main surface. This is because a carbon structure composed of a carbon fiber aggregate is disposed in a graphite structure in which the -b axis is substantially oriented.

  With this configuration, there is a carbon structure composed of carbon fiber aggregates appropriately disposed inside the graphite structure while maintaining the high thermal conductivity in the plane direction of the graphite structure as a base material, so that the layer direction ( Heat also efficiently propagates through this carbon structure in the thickness direction). As a result, it is possible to improve the layer direction thermal conductivity κ⊥ as compared with the case of the graphite structure alone, and it is possible to contribute to an increase in the tensile strength and thickness of the member.

  In the configuration of the present invention, since the shape of the high thermal conductivity member is a film shape, space saving properties and shape diversity are increased, so that applicability (degree of freedom) as a thermal conductive member can be expanded. Therefore, it is preferable.

  Further, in the configuration of the present invention, it is preferable that the pore structure is included in the graphite structure because flexibility and compressibility can be imparted as a high thermal conductive member to be obtained. The flexibility in the present specification indicates the bending resistance to the bending process, and it is possible to dramatically improve the number of bending resistances by enclosing holes as in the configuration of the present invention. . In addition, the compressibility indicates a deformability with respect to the compression process, and by including a hole as in the configuration of the present invention, it is possible to increase the degree of adhesion with a heat source or the like and suppress the thermal resistance. Become. As a result, the density of the obtained high thermal conductivity member is about 0.30 g / cm3 to 2.00 g / cm3, which can be made lighter than the conventional heat radiating material.

  In the configuration of the present invention, the carbon structure composed of the carbon fiber aggregate is in the form of a mesh, a woven fabric, or a non-woven fabric, so that the carbon structure having a desired form can be easily arranged in the graphite structure. It becomes possible.

  In the structure of the present invention, the carbon structure comprising the carbon fibers contained in the graphite structure is a mesh-like structure in which carbon fibers selected from a diameter of φ0.5 μm to φ500 μm are arranged at intervals selected from 0.01 μm to 10 mm. Because of the woven or non-woven structure, it is easy to arrange a carbon structure that enhances the thermal conductivity in the layer direction while maintaining the crystallinity (orientation) of the graphite structure as the base material. This is preferable.

  Moreover, in the structure of this invention, since the said carbon structure is a structure which laminated | stacked mesh shape, woven fabric shape, or nonwoven fabric-like carbon, since it becomes easy to raise design freedom, such as thickness, it is preferable.

  Further, in the configuration of the present invention, the thermal conductivity κ 方向 in the direction parallel to the main surface (plane direction) is in the range of 400 W / m · K or more and 1500 W / m · K or less, and in the vertical direction (layer Direction) is in the range of 10 W / m · K or more and 150 W / m · K or less, which is preferable because it can be used even when it is difficult to apply the conventional heat dissipation material. More preferably, the surface direction thermal conductivity κ‖ is 700 W / m · K or more and 1500 W / m · K or less, and the layer direction thermal conductivity κ⊥ is 50 W / m · K or more, 150 W / m · K or less.

  Moreover, the manufacturing method of the high heat conductive member of this invention is a manufacturing method of the high heat conductive member which a main component consists of carbon (C), Comprising: (1) The solution which forms a 1st organic polymer body is prepared. A step, (2) impregnating or coating a carbon structure comprising a carbon fiber aggregate with a solution for forming the first organic polymer, and (3) forming the first organic polymer. A step of solidifying the solution to be formed; (4) a step of converting the first organic polymer into a second organic polymer to be a carbon precursor by a reaction process such as heat dehydration; And baking the second organic polymer in a predetermined atmosphere according to a predetermined temperature profile.

  With this configuration, it is possible to easily produce a graphite structure as a base material with high orientation, and it is possible to easily arrange a carbon structure made of a carbon fiber aggregate in a desired state.

  Moreover, the manufacturing method of the high heat conductive member of this invention is a manufacturing method of the high heat conductive member which a main component consists of carbon (C), Comprising: (1) The solution which forms a 1st organic polymer body is prepared. A step, (2) impregnating or coating a polymer structure comprising a fibrous polymer aggregate with a solution for forming the first organic polymer, and (3) the first organic polymer. A step of solidifying a solution for forming a body, and (4) a step of converting the first organic polymer into a second organic polymer to be a carbon precursor by a reaction process such as heat dehydration, 5) A step of baking the second organic polymer in a predetermined atmosphere according to a predetermined temperature profile.

  With this configuration, it is possible to easily produce a graphite structure as a base material with high orientation, and it is possible to easily arrange a carbon structure made of a carbon fiber aggregate in a desired state.

  In the production method of the present invention, since the solution for forming the first organic polymer is a polyamic acid solution, it is easy to handle and can form a highly oriented graphite structure. preferable.

  In the production method of the present invention, the second organic polymer is preferably polyimide (PI), so that it is easy to handle and can form a highly oriented graphite structure.

  Further, in the production method of the present invention, the temperature process of the firing step is pre-baked at a predetermined temperature selected from a temperature range of 1000 ° C. to 1500 ° C., and at a predetermined temperature selected from a temperature range of 2000 ° C. to 3000 ° C. The step of firing is preferable because a graphite structure having higher in-plane orientation than the second organic polymer can be formed.

  In the production method of the present invention, the polymer structure composed of the fibrous polymer aggregate is preferably polyimide (PI), which makes it possible to form a highly oriented carbon structure.

  In the heat dissipation system of the present invention, the heat generation source and the heat dissipation member are thermally connected via the high thermal conductivity member described above.

  With this configuration, it is possible to design a heat dissipation system having a high degree of freedom in the shape of the heat dissipation system and excellent heat dissipation characteristics.

  As described above, according to the high thermal conductivity member of the present invention, the structure in which the carbon structure composed of the carbon fiber aggregate that supplements the layer direction thermal conductivity is arranged in the graphite structure having a high surface direction thermal conductivity. Since it applied, the high heat conductive member which has a high heat conductive function as a whole can be provided. Furthermore, since a mesh-like woven fabric or non-woven fabric structure made of a carbon structure is incorporated in the graphite structure, it becomes possible to increase the degree of design freedom such as member thickness and tensile strength.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a schematic perspective view (a) and a schematic sectional view (b) of a high thermal conductivity member in an embodiment of the present invention. The high thermal conductivity member is basically composed of a graphite structure 1 in which the ab axis is substantially oriented in a direction parallel to the main surface (plane direction), and substantially uniform in the graphite structure 1. And the carbon structure 3 disposed in the. In the figure, two layers of carbon structures 3 are shown as stacked, but this is not restrictive, and one layer may be used, or three or more layers may be stacked. When a plurality of layers are included, the carbon structures 3 may be in close contact with each other, or may be appropriately dispersed and disposed inside the graphite structure 1.

  The graphite structure 1 has a structure in which the graphene layer 2 having a carbon six-membered ring structure is laminated in a layered manner with a correlation as described above. Specifically, when this graphite structure 1 is evaluated by an X-ray diffraction method, the distance d between crystal planes is in the range of d = 0.335 to 0.340 nm (reported value of single crystal graphite: 0.335 nm), and ( It is preferable to use one having no diffraction peak other than the (002) plane and its higher order peak. FIG. 4 shows a typical X-ray diffraction pattern of the graphite structure 1. Also for the crystallinity (orientation), a half width of 1 ° or less with respect to the main peak near 26.5 ° shown in FIG. 4 is preferably applied. The plane direction thermal conductivity κ‖ of the graphite structure 1 alone exhibiting such crystallinity (orientation) is generally 400 W / m · K or more although it depends on the production method and the like. A graphite structure of> 400 W / m · K is suitable.

  As described above, the graphite structure 1 used for the base material in the present invention can be any single crystal graphite as long as it has a high thermal conductivity in the plane direction. Highly oriented graphite having a structure close to a single crystal, which is obtained by a method of graphitizing by pyrolyzing) by baking treatment, is preferred. Therefore, in the following embodiment, an example using a graphite structure 1 obtained by firing a film-like organic polymer material will be mainly described.

  In the carbon structure 3 applied in the present invention, heat propagating through the graphite structure 1 is thermally connected not only in the plane direction but also between the graphene layer structures, and heat is also propagated in the layer direction (thickness direction). It has a function to make it. At the same time, the tensile strength of the entire high thermal conductivity member can be increased and the thickness can be increased. Therefore, it is a member having high thermal conductivity in the plane direction and the layer direction and having an excellent balance in which the thickness and tensile strength are increased.

  The carbon structure 3 composed of the carbon fiber aggregate used in the present invention is not particularly limited as long as it has a relatively high thermal conductivity. For example, carbon fiber (trade name: Torayca cloth, type: Carbon Fabrics manufactured by Toray Industries, Inc.) ) Etc. can be used. The shape may be any carbon fiber in a mesh, woven or non-woven shape. For example, a carbon fiber having a diameter selected from a range of φ0.5 μm to φ500 μm is selected from 0.01 μm to 10 mm. A mesh shape knitted at a selected interval, a woven fabric shape of similar carbon fibers knitted at a density of about 10 fibers / cm to 10,000 fibers / cm, or a nonwoven fabric structure in which similar carbon fibers are intertwined are suitable. It is.

  Further, as the carbon structure 3 made of the carbon fiber aggregate used in the present invention, it is not necessary to use the carbon fiber itself, and in the firing process in which the base material is graphitized, it changes to the carbon structure having the thermal conductivity. A fibrous polymer material can also be used as a raw material. For example, a fibrous polyimide having a diameter of several to several tens of μm in a mesh shape, or a woven or non-woven fabric made of fibrous polyimide may be used as a raw material, and the carbon structure may be formed by firing. .

(Embodiment 2)
FIG. 2 shows a schematic perspective view (a) and a schematic sectional view (b) of a high thermal conductivity member in another embodiment of the present invention. The structure is basically the same as that of the first embodiment, but in this embodiment, the graphite structure 1 in which the ab axis is substantially oriented in a direction parallel to the main surface (plane direction). The carbon structure 3 is disposed only on one side. In the figure, two layers of carbon structures 3 are shown as stacked, but this is not restrictive, and one layer may be used, or three or more layers may be stacked.

  As the carbon structure 3 used in the present embodiment, the woven or non-woven carbon structure mainly described in the first embodiment is suitable.

(Embodiment 3)
Although there are several means for producing a high thermal conductivity member having the above-mentioned configuration, from the viewpoint of ease of production and obtained characteristics, the carbon structure (for example, TORAYCA cloth) is a polymer that is easily graphitized. The best method is to form a composite structure in which a carbon structure is arranged in a graphite structure by impregnating or applying a solution and baking. Therefore, this example will be described in this embodiment.

  There is a large method for obtaining a high thermal conductive member composed of a composite structure of graphite and a carbon structure using an organic polymer material as a starting material. Step (I) An organic polymer material is impregnated or coated on a carbon structure. It comprises a step of disposing a carbon structure in the molecular body, and a step (II) of firing it to graphitize the organic polymer.

  First, the step of forming an organic polymer body in which the carbon structure in step (I) is disposed will be described. The organic polymer body in which the carbon structure 3 composed of the carbon fiber aggregate is arranged is impregnated or applied to the carbon structure 3 with the first organic polymer solution mixed in the solvent to obtain a predetermined shape, It can be obtained by synthesizing a second organic polymer that is easily graphitized through a reaction process such as a heat dehydration reaction. At this time, a catalyst may be used as necessary.

  In this step, the first organic polymer material dissolved in the solvent is solidified by volatilizing the solvent, and further heated and dehydrated to form the second organic polymer. At that time, the degree of molecular arrangement of the polymer can be controlled by the organic polymer material used. Specifically, the composition of the polymer raw material and the solvent, which are solid components, is determined so that a polymer having a predetermined orientation and having the carbon structure 3 disposed thereon is obtained. If necessary, a catalyst, a viscosity modifier or the like is added to the solution prepared to the composition and stirred, and the desired use form is obtained by casting / coating. By volatilizing the solvent in this state, the first organic polymer solution is solidified. The temperature condition during the production may be near room temperature, which is a normal working temperature, but may be heated to a temperature below the boiling point of the solvent as necessary.

  Further, the obtained first organic polymer material is changed into a second organic polymer material that becomes a carbon precursor by a reaction process such as heat dehydration. In general, heat treatment is performed in a nitrogen atmosphere or a vacuum atmosphere, or dehydration is performed by a chemical reaction, but the optimum method differs depending on the organic polymer material to be formed. From the viewpoint of ease of production, those capable of carrying out the reaction process by a method of heating in a temperature range of about 100 to 400 ° C. are preferable. Further, in order to control the orientation, stretching may be performed simultaneously.

  The organic polymer material applicable in the present invention is only required to be able to form a highly oriented graphite structure by firing treatment, such as polyimide (PI), polyamide (PA), polyphenylene terephthalamide (PPTA), polyphenylene oxadiazole. (POD), polybenzothiazole (PBT), polybenzobisthiazole (PBBO), polyphenylenebenzimidazole (PBI), polyphenylenebenzobisimidazole (PPBI), polythiazole (PT), polyparaphenylene vinylene (PPV), etc. be able to. Of these, polyimide is preferred.

  As the solvent, it is sufficient that the first organic polymer material is dissolved, and general organic solvents such as dimethylacetamide and N-methylpyrrolidone can be used alone or in combination.

  In addition, a filler such as calcium hydrogen phosphate may be appropriately mixed in order to relax the chargeability of the organic polymer formed.

  Next, the step (II) for obtaining oriented graphite from the second organic polymer in which the obtained carbon structure is arranged will be described.

  First, the second organic polymer that is the carbon precursor prepared in the above step is pre-fired, and components other than carbon (C) contained in the organic polymer (oxygen (O), nitrogen (N) , Hydrogen (H), etc.) are removed. The treatment temperature and treatment time depend on the shape and size of the sample to be fired, but are generally 1000 to 1500 ° C. and 0.5 to 5 in an argon (Ar) or nitrogen (N2) atmosphere or a mixed atmosphere thereof. It's time. The heating rate is preferably in the range of 1 to 15 ° C./min, particularly in the range of 3 to 10 ° C./min. Moreover, it is preferable to cool in the range of 5-20 degreeC / min as a temperature-fall rate after a preliminary baking process, especially the range of 5-10 degreeC / min.

  Under the above conditions, the plane direction thermal conductivity and the degree of orientation of the graphite structure 1 obtained after the main firing treatment can be increased.

  The pre-fired sample is fully fired at a predetermined temperature selected from a temperature range of 2000 to 3000 ° C. in order to make the portion other than the carbon structure 3 into oriented graphite in earnest. At that time, the degree of orientation of the resulting graphite structure 1 can be increased by performing an intermediate treatment (generally 2000 to 2400 ° C.) that is held at a predetermined heating temperature. Specifically, it is heated from room temperature to a predetermined intermediate temperature at a heating rate of 5 to 10 ° C./min, held for about 1 hour, then heated again and fired. The main firing conditions are approximately in the temperature range of 2000 to 3000 ° C. and heating for about 0.5 to 10 hours. The cooling after the main baking treatment is preferably performed in the range of 5 to 20 ° C./min, particularly in the range of 5 to 10 ° C./min as the temperature lowering rate. FIG. 5 shows a schematic diagram of a reaction that may occur in the above baking step.

  Through the steps as described above, the graphite structure 1 having a high surface direction thermal conductivity of the present invention can be formed, and further, the layer direction thermal conductivity is obtained by the action of the carbon structure 3 arranged in the structure. Is also improved. At the same time, the tensile strength is improved by incorporating the carbon structure from the graphite alone. Furthermore, by stacking the carbon structure 3 and the graphite layer, a very thick heat conduction member can be manufactured.

  Furthermore, in the graphite structure 1 in which the carbon structure 3 obtained by this method is disposed, by adjusting the firing conditions (mainly the heating rate), or by appropriately mixing the filler and performing a firing treatment, While the graphene structure 2 is oriented two-dimensionally, it is possible to produce a structure in which many fine pores are included inside the structure. Due to the pore region, the density of the portion of the graphite structure 1 to be formed can be made smaller (0.30 to 2.00 g / cm 3) than the original graphite value (˜2.26 g / cm 3). By setting it as such a structure, the obtained high heat conductive member has a softness | flexibility, and even if it bends, it becomes a structure which does not generate | occur | produce a cutting | disconnection etc. easily, and deform | transforms moderately also to compression. Such characteristics have the effect of increasing the degree of design freedom when used as a thermally conductive member and reducing the thermal contact resistance with the heat source.

(Embodiment 4)
As described in the third embodiment, the high thermal conductivity member of the present invention can be produced using a material that has already been carbonized as the carbon structure 3, but in the graphitization process of the step (II), At the same time, the polymer structure disposed inside is carbonized to form the carbon structure 3, whereby a composite structure in which the carbon structure 3 is disposed in the graphite structure 1 can be formed. Therefore, this example will be described in this embodiment.

  The basic manufacturing process is exactly the same as in the third embodiment.

  First, as step (I), a first organic polymer solution dissolved in a solvent is impregnated or applied to a polymer structure composed of a fibrous polymer aggregate that can be carbonized by a baking treatment, Then, a second organic polymer that is easily graphitized is synthesized by solidifying by volatilizing the solvent and passing through a reaction process such as a heat dehydration reaction.

  Examples of the polymer structure material comprising a fibrous polymer aggregate that can be used in the present invention include polyimide (PI), polyamide (PA), polyphenylene terephthalamide (PPTA), polyphenylene oxadiazole (POD), Examples thereof include polybenzothiazole (PBT), polybenzobisthiazole (PBBO), polyphenylenebenzimidazole (PBI), polyphenylenebenzobisimidazole (PPBI), polythiazole (PT), polyparaphenylene vinylene (PPV), and the like. Among these, polyimide is suitable, and Kapton manufactured by Toray DuPont and processed into a fibrous form can be used.

  The next step (II) is exactly the same. As described above, in this step, the region of the second organic polymer body becomes the graphite structure 1 having a high surface direction thermal conductivity, and the polymer structure disposed inside is also carbonized. Depending on the case, since it is graphitized, the laminar thermal conductivity can be improved by the action of the carbon structure 3 arranged in the graphite structure 1.

  Hereinafter, the present invention will be specifically described by way of examples.

(Example 1)
A description will be given of an example in which a polyimide structure having a carbon structure disposed therein is prepared by adopting polyimide as an organic polymer material as a raw material and firing it. FIG. 6 shows the main process diagram.

  First, a polyamic acid solution was prepared as a polyimide precursor organic polymer solution. The procedure involves adding 5.00 g of bis (4-aminophenyl) ether, 120 ml of dimethylacetamide, and 5.45 g of pyromellitic anhydride in a dry box filled with nitrogen (N2) gas to a round bottom flask. By mixing and stirring for about 3 hours, a polyamic acid solution as the first organic polymer material was synthesized.

  A mesh (size: 30 mm × 30 mm, thickness: 100 μm) made of carbon fiber was immersed in the synthesized polyamic acid solution. In this example, a carbon mesh in which carbon yarns produced by twisting about 1000 carbon fibers having a diameter of about 7 μm and arranged at intervals of about 2 mm was used. Specifically, the polyamic acid solution was placed in a chalet having an inner diameter of φ60 mm, and a carbon mesh was placed therein, so that the polyamic acid was present almost equally up and down with the carbon mesh in the center. In this case, the thickness of the solution layer was about 500 μm.

  The sample thus produced was dried in a nitrogen atmosphere for about 1 hour, then dried in a vacuum oven for 2 hours (room temperature), and further heated to 100 ° C. and heat-treated for 1 hour. As a result, the solvent component of the solution was removed by evaporation, and a polyamic acid film having a carbon mesh disposed therein was formed.

  Further, the obtained sample was placed in a glass tube oven, decompressed to a vacuum, and then heat treated at 300 ° C. for 1 hour to polyimidize the polyamic acid.

  When the obtained carbon mesh was peeled off from the petri dish and the thickness was measured with a micrometer, it was about 380 μm.

  The polyimide obtained in the above steps was put in an electric furnace and fired. FIG. 7A shows the temperature profile of the pre-baking employed in this example.

  First, as pre-baking, the temperature was increased from room temperature to 1200 ° C. in an Ar atmosphere at a rate of temperature increase of 3 ° C./min, and the pre-baking temperature was maintained at 1200 ° C. for 3 hours. The rate of temperature increase may be determined in consideration of the type and shape of the organic polymer film to be baked, but generally the range of 15 ° C / min or less is good, and in this example 3 ° C / min was adopted. . After the firing treatment, it was cooled to room temperature at a rate of 5 ° C./min. In general, the cooling rate during cooling does not need to be controlled as strictly as the heating rate, but is preferably 10 ° C./min or less, and 5 ° C./min was adopted in this example.

  In this pre-baking step, the organic polymer portion is thermally decomposed and nitrogen, oxygen, and hydrogen are released, so that the weight of the polyimide portion becomes 50 to 60% of the initial value and changes to a carbon film. Therefore, there is no influence on the carbon mesh arranged inside.

  After pre-baking under the above conditions, the sample was further transferred to an ultra-high temperature furnace to perform main baking. The temperature profile is shown in FIG. In this example, the temperature was increased up to 1000 ° C. at a rate of temperature increase of 10 ° C./min, and thereafter, 5 ° C./min was set at an intermediate treatment temperature of 2200 ° C. for 1 hour. Further, the heating rate was 5 ° C./min up to the main firing temperature of 2700 ° C., and the holding time at 2700 ° C. was 3 hours. The cooling after holding the main firing temperature was 5 ° C / min until 2200 ° C, then 10 ° C / min until 1300 ° C and 20 ° C / min until room temperature.

  The film thickness of the graphite structure 1 in which the carbon mesh thus obtained is arranged is about 300 μm. When the cross section of the structure obtained with a scanning electron microscope (SEM) is observed, the carbon structure 3 It was confirmed that the graphene structure 2 was laminated in a layered manner around the graphite structure 1. Further, it was confirmed that many fine pore regions exist in the portion of the graphite structure 1 other than the carbon structure 3. Although the formation mechanism is not clear, it is thought to be due to the main firing program. Furthermore, it was also observed that three carbon structures were firmly arranged between the upper and lower graphene structures 2 oriented in the plane direction.

  Further, as a result of evaluating the crystal structure of the graphite structure 1 including the formed carbon structure 3 by X-ray diffraction, graphite (002) equivalent to FIG. 4 and its higher order peak were observed, and the carbon structure 3 It was found that a graphite structure having a sufficiently high orientation in the plane direction was obtained even in the case of containing.

  The heat conduction characteristics of the graphite structure 1 including the carbon structure 3 obtained by the above process were evaluated. As a result, the surface direction thermal conductivity κ‖ was 500 W / m · K slightly lower than that of the graphite sheet (about 600 W / m · K) produced without including the carbon structure 3, but the layer direction ( (Thickness direction) The thermal conductivity κ⊥ was 25 W / m · K, which is several times the conventional value.

  Therefore, by arranging the carbon structure 3 in the highly oriented graphite structure 1, the graphite structure 1 having high thermal conductivity in the plane direction and further improved thermal conductivity in the layer direction can be obtained. It was confirmed.

  In addition, the high thermal conductivity member produced in this example has a large number of fine pore regions in the graphitized region, and the carbon structure 3 also has a mesh shape. A highly thermally conductive member having a high compressibility was obtained. At the same time, since the carbon structure 3 is disposed inside, a thick heat conductive member, which has been difficult to produce in the past, can be formed, and the tensile strength is also increased.

(Example 2)
A description will be given of the results when the interval of the mesh structure is changed when a highly thermally conductive member made of the graphite structure 1 in which the carbon structure 3 is disposed in the same process as in Example 1.

  In this example, a carbon structure 3 was produced by knitting the carbon yarn used in Example 1 with a mesh interval of 1 to 4 mm, and the thermal conductivity in the plane direction and the layer direction was evaluated.

  These carbon meshes were immersed and placed in the polyamic acid as the first organic polymer solution, and a highly heat conductive member made of the graphite structure 1 in which the carbon mesh was placed in the same process was formed.

  As a result of evaluating the thermal conductivity characteristics of the obtained sample, the surface direction thermal conductivity κ⊥ showed 480 to 600 W / m · K in proportion to the mesh interval, whereas the layer direction thermal conductivity κ⊥ was A value of 20-80 W / m · K was shown in inverse proportion to the mesh spacing. That is, when the graphite structure 1 is produced by changing the interval between the carbon meshes in the range of 1 to 4 mm, it is desirable that the mesh interval is wide with respect to the heat conduction in the plane direction, and the interval in the layer direction is relatively narrow. It was confirmed that this was preferable. However, in any case, the heat conduction in the layer direction is improved as compared with the case where the carbon structure 3 is not included, and the carbon structure 3 efficiently propagates the heat conduction in the layer direction in the graphite structure 1. Was confirmed.

(Example 3)
In the same process as in Example 1, when producing a high thermal conductivity member composed of the graphite structure 1 with the carbon structure 3 disposed therein, the upper surface (one side) of the graphite structure 1 is made of woven carbon as a base material. The results when

  In Examples 1 and 2, the graphite structure 1 was formed on the upper and lower surfaces using a mesh-like carbon structure. However, in this example, the carbon structure 3 was disposed only on the upper surface (surface, one side) of the graphite structure 1. did. That is, the polymer solution was applied to the upper surface of a carbon woven fabric having a thickness of 100 μm, and the graphite structure 1 was produced in the same process. In this example, it is considered that a part of the polymer applied to the upper surface is impregnated inside the carbon woven fabric.

  As a result of evaluating the thermal conductivity characteristics of the obtained sample, the surface direction thermal conductivity κ‖ showed about 500 W / m · K as in Example 1, but the layer direction thermal conductivity κ⊥ was 20 to A value of 50 W / m · K was obtained.

Example 4
The carbon precursor organic polymer material used in Example 1 was polyimide, but it was confirmed that the graphite structure 1 could be produced by the same manufacturing method as described above using other organic polymer materials. did. Specifically, in addition to polyimide (PI), polyamide (PA), polyphenylene terephthalamide (PPTA), polyphenylene oxadiazole (POD), polybenzothiazole (PBT), polybenzobisthiazole (PBBO), polyphenylene benzimidazole ( A graphite structure 1 in which a carbon structure 3 is arranged inside is obtained using an organic polymer material such as PBI), polyphenylenebenzobisimidazole (PPBI), polythiazole (PT), polyparaphenylene vinylene (PPV).

(Example 5)
In the same process as in Example 1, a fibrous polymer structure that can be carbonized during the firing process was used when a highly thermally conductive member composed of the graphite structure 1 with the carbon structure 3 disposed therein was produced. The case results are described below.

  In this example, a polymer structure in which a fibrous polyimide having a diameter of about 10 μm is twisted to form a mesh is immersed in a polyamic acid solution to form a polyamic acid film having a polymer mesh disposed therein, and then a polyamide is formed. The acid was polyimideized.

  The polyimide obtained in the above steps was put in an electric furnace and fired. The temperature profile employed in this example is the same as that in Example 1.

  As a result, first, in the pre-baking process, the second organic polymer portion was pyrolyzed and changed into a carbon film, and the polymer mesh portion disposed inside was also carbonized.

  Further, in the firing process, the second organic polymer portion is changed to the graphite structure 1 in which the graphene structure 2 is laminated in layers, and the portion where the polymer mesh is carbonized is further carbonized, and partially Was confirmed to be graphitized having a layered structure.

  The heat conduction characteristics of the graphite structure 1 including the carbon structure 3 obtained by the above process were evaluated. As a result, the surface direction thermal conductivity κ‖ was 500 to 550 W / m · K, which is slightly lower than that of the graphite sheet prepared without including the carbon structure (about 600 W / m · K), but the layer direction (Thickness direction) Thermal conductivity κ⊥ was 50-100 W / m · K.

  Therefore, by arranging the carbon structure 3 in the highly oriented graphite structure 1, the graphite structure 1 having high thermal conductivity in the plane direction and further improved thermal conductivity in the layer direction can be obtained. It was confirmed.

(Example 6)
A heat dissipation system was prototyped using a high thermal conductivity member made of the graphite structure 1 in which the carbon structure obtained in Example 1 was placed, and its thermal resistance was measured. FIG. 8A shows a structure in which the high heat conductive member 7 of the present invention is brought into close contact between the heat source 6 and the heat radiating member 8 to radiate heat. For comparison, a case where a copper plate or highly oriented graphite (PGS graphite sheet manufactured by Matsushita) was applied was also evaluated. The measurement was performed under constant pressure (10N / cm2).

  As a result, the thermal resistance in the case of the copper plate is 1.0 ° C./W, and in the highly oriented graphite sheet, it was about 0.4 ° C./W, whereas when using the highly thermally conductive member of the present invention, It was confirmed that the thermal resistance characteristics were improved by 0.3 ° C / W.

  In addition, in the configuration of FIG. 8B and the configuration in which a part of the high thermal conductivity member 7 is bent in FIG.

  The highly thermally conductive member of the present invention is not only useful as a heat dissipation system material used in parts requiring heat countermeasures such as various electronic devices / devices represented by CPUs and lasers, but can be processed into various forms. As a result, it can be applied to a wide variety of applications such as a substrate stage and a mask stage, for example, where temperature uniformity is required.

Schematic of high thermal conductivity member of the present invention Schematic of another high thermal conductivity member of the present invention Diagram showing the crystal structure of graphite The figure which shows the typical X-ray-diffraction pattern of the orientation graphite structure 1 Schematic diagram showing the process from organic polymer film to oriented graphite structure Production process diagram of graphite structure with carbon structure inside The figure which shows the example of the temperature program of the baking process in Example 1. The figure which shows the example of the thermal radiation system using the high thermal conductive member of this invention Schematic diagram of Conventional Example 1 Schematic diagram of Conventional Example 2 Schematic diagram of Conventional Example 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Graphite structure 2 Graphene structure 3 Carbon structure 4 Carbon atom 5 Graphene structure 6 Heat source 7 High thermal conductivity member 8 Heat dissipation member

Claims (14)

A high thermal conductivity member whose main composition is carbon (C),
A highly thermally conductive member in which a carbon structure composed of a carbon fiber aggregate is disposed in a graphite structure in which ab axes are substantially oriented in a direction parallel to the main surface (plane direction). The high thermal conductivity member according to claim 1,
A shape of the high thermal conductivity member is a film shape. The high thermal conductivity member according to claim 1,
A highly thermally conductive member characterized in that a pore region is included inside the graphite structure. The high thermal conductivity member according to claim 1,
A high thermal conductivity member, wherein the carbon structure composed of the carbon fiber aggregate is in a mesh shape, a woven fabric shape or a non-woven fabric shape. The high thermal conductivity member according to claim 1,
The carbon structure composed of the carbon fiber aggregate has a mesh-like, woven-like or non-woven-like structure in which carbon fibers selected from a diameter of φ0.5 μm to φ500 μm are arranged at intervals selected from 0.01 μm to 10 mm. A highly thermally conductive member characterized by that. The high thermal conductivity member according to claim 1,
The high thermal conductivity member, wherein the carbon structure has a structure in which mesh-like, woven or non-woven carbon is laminated. In the high thermal conductivity member according to claim 1,
Thermal conductivity κ‖ in the direction parallel to the main surface (plane direction) is in the range of 400 W / m · k or more and 1500 W / m · K or less, and in the perpendicular direction (layer direction) A high thermal conductivity member, wherein κ⊥ is in the range of 10 W / m · k to 150 W / m · k. A method for producing a high thermal conductivity member comprising carbon (C) as a main component,
(1) preparing a solution for forming the first organic polymer,
(2) impregnating or applying a solution for forming the first organic polymer to a carbon structure composed of a carbon fiber aggregate;
(3) solidifying a solution for forming the first organic polymer;
(4) a step of converting the first organic polymer into a second organic polymer to be a carbon precursor by a reaction process such as heat dehydration;
(5) A method for producing a high thermal conductivity member comprising a step of firing the second organic polymer in a predetermined atmosphere according to a predetermined temperature profile. A method for producing a high thermal conductivity member comprising carbon (C) as a main component,
(1) preparing a solution for forming the first organic polymer,
(2) impregnating or applying a solution for forming the first organic polymer to a polymer structure composed of a fibrous polymer aggregate;
(3) solidifying a solution for forming the first organic polymer;
(4) a step of converting the first organic polymer into a second organic polymer to be a carbon precursor by a reaction process such as heat dehydration;
(5) A method for producing a high thermal conductivity member comprising a step of firing the second organic polymer in a predetermined atmosphere according to a predetermined temperature profile. In the manufacturing method of the high thermal conductivity member according to claim 8 and 9,
The method for producing a high thermal conductivity member, wherein the solution for forming the first organic polymer is a polyamic acid solution. In the manufacturing method of the high thermal conductivity member according to claim 8 and 9,
The method for producing a high thermal conductivity member, wherein the second organic polymer is polyimide (PI). In the manufacturing method of the high thermal conductivity member according to claim 8 and 9,
The temperature process of the baking step is a step of pre-baking at a predetermined temperature selected from a temperature range of 1000 ° C. to 1500 ° C .;
A method for producing a highly thermally conductive member comprising a step of main firing at a predetermined temperature selected from a temperature range of 2000 ° C to 3000 ° C. In the manufacturing method of the high thermal conductivity member according to claim 9,
A method for producing a high thermal conductivity member, wherein the polymer structure composed of an aggregate of fibrous polymers is polyimide (PI). A heat dissipating system in which a heat source and a heat dissipating member are thermally connected via the high thermal conductivity member according to claim 1.

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