JP2005213459A - High thermal conductive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal conductive material having a metal-level high thermal conductivity and a polymeric resin-level lightness at a low cost. <P>SOLUTION: In the high thermal conductive material, carbon fibers 2a arranged in one direction are impregnated in a polymer matrix material 4 and further thermal conductive fillers 3 are contained in the polymer matrix material. The carbon fiber has a thermal conductivity of 300 W/mK or more and the thermal conductive filler is desirably a spherical aluminum oxide powder having an average grain size of 1 to 35μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a composite material that takes advantage of the high thermal conductivity of carbon fiber, and can be used as a material for heat dissipation / heat conduction in electronic equipment and a housing material for electronic equipment. The present invention relates to a high thermal conductive carbon fiber composite material.

  In recent years, as represented by a CPU, the speed of semiconductor elements has been increased, and accordingly, the heat generated by electronic components has been increasing. On the other hand, miniaturization and high-density mounting are progressing in electronic devices incorporating electronic components, particularly electronic devices such as notebook computers, mobile phones, and portable information terminals suitable for mobile or ubiquitous. Therefore, how to remove the heat generated in the device without increasing the size and weight of the device is a big problem compared to the conventional case.

For such problems, countermeasures are usually taken using a radiator, a radiator plate and a radiator sheet, and a method for increasing the heat conductivity of the material constituting the radiator, radiator plate and radiator sheet is proposed. I came. Among these, carbon fibers and graphitized carbon are variously disclosed to be useful for increasing the thermal conductivity of metals and polymers. For example, Patent Document 1 discloses a heat dissipation composite material of high thermal conductivity carbon fiber and epoxy resin. However, in this example, the carbon fiber alone has a thermal conductivity higher than that of a metal of 620 W / mK, while the heat dissipation composite material can only achieve a thermal conductivity of 220 W / mK, comparable to aluminum. Patent Document 2 proposes a heat dissipation material in which various metals are impregnated with carbon fiber, graphitized carbon fiber, and silicon carbide. In this example, 265 W / mK is obtained when the carbon fiber is impregnated with aluminum, and 510 W / mK and 525 W / mK are obtained when the graphitized carbon fiber is impregnated with aluminum and oxygen-free copper, respectively. However, when carbon fiber is used, it is only an increase of 35 W / mK compared to the thermal conductivity of 230 W / mK with aluminum alone. In addition, when graphitized carbon fiber is used, thermal conductivity exceeding copper (390 W / mK) is achieved, but graphitized carbon fiber is expensive, and heat dissipation materials using this are also expensive. I cannot help it. In any of the examples, since the metal is used for the matrix, the demand for weight reduction of the electronic device cannot be satisfied. Patent Document 3 discloses a heat conductive sheet in which graphitized carbon fibers are magnetically oriented in a polymer. In this example, the thermal conductivity is only 2.56 W / mK despite the addition of aluminum oxide and aluminum hydroxide powder in addition to the graphitized carbon fibers that are costly. This is because short fibers are used as carbon fibers, and even though they can be used as heat radiating sheets, they cannot be used because they have too low thermal conductivity as heat radiators or other heat conductive materials. Further, in Patent Document 4, as a molded product such as a heat exchanger tube having excellent mechanical strength in addition to thermal conductivity, a thermosetting resin containing graphite powder is impregnated into carbon fibers aligned in one direction. Thermally conductive molded products have been proposed. However, even in this example, the thermal conductivity is only 2.4 to 9.9 W / mK. Therefore, even if it can be used as a molded product such as a heat exchanger tube for a heat exchanger, it cannot be used because it has a low thermal conductivity as a heat radiator or other heat conduction material for electronic equipment.
JP 2000-124369 A JP 2003-309232 A JP 2003-200437 A Japanese Patent Laid-Open No. 5-17593

  Therefore, an object of the present invention is to provide a low-cost thermal conductive member that is as light as a polymer resin while having a high thermal conductivity equivalent to that of a metal.

  In order to solve the above-mentioned problems of the prior art, the present invention is a high heat treatment in which a long fiber bundle of carbon fibers having high thermal conductivity is impregnated into a matrix of a polymer resin and processed by adding a thermal conductive filler. Conductive composite material.

  That is, the present invention is characterized in that carbon fibers aligned in one direction are contained in a polymer matrix material, and further a thermally conductive filler is contained in the polymer matrix material. It is achieved by the material.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the high heat conductive composite material which has high heat conductivity like a metal, and the lightness like a resin at low cost. In addition, the high thermal conductive composite material of the present invention is excellent in high thermal conductivity, low cost, light weight and excellent in strength. Therefore, heat dissipation / heat conduction materials in electronic devices, housing materials for electronic devices, etc. It can be used widely.

  In the high thermal conductivity (composite) material of the present invention, carbon fibers aligned in one direction are contained in a polymer matrix material, and further, a thermally conductive filler is contained in the polymer matrix material. It is a feature.

  The present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view schematically showing an embodiment of the structure of a high thermal conductive composite material according to the present invention. FIG. 1A is a schematic view showing a section cut along a plane perpendicular to the direction of carbon fibers aligned in one direction, and FIG. 1B is a plane parallel to the carbon fiber direction. FIG.1 (c) is an expanded sectional view of one carbon fiber aligned in one direction in Fig.1 (a).

  As shown in FIG. 1, the high thermal conductive composite material 1 of the present invention is impregnated with a polymer matrix material 4 with high thermal conductivity carbon fibers 2 aligned in one direction. The filler 3 is contained. In addition, as shown in FIG.1 (c), one carbon fiber is comprised from the long fiber bundle of the carbon fiber arranged in one direction. In this long fiber bundle, a plurality of carbon fiber filaments 2a are bundled. Further, the polymer matrix material 4 may be impregnated between the carbon fiber filaments 2a in the long fiber bundle.

  Next, FIG. 2 shows an example of a heat conduction path as to how heat is conducted in the high heat conduction composite material of the present invention.

  In the example shown in FIG. 2, the heat received by the high heat conductive composite material 1 from the heating element 5 such as an electronic component in the electronic device is conducted through the following paths (the heat conduction paths are indicated by arrows in the figure). .

  A path indicated by (1) in the figure; it conducts through the high thermal conductivity carbon fiber 2 in the fiber direction.

  A route indicated by (2) in the figure; the polymer matrix material 4 is conducted through the thermally conductive filler 3.

  The route passing from (3) to (2) in the figure; after conducting in the fiber direction through the high thermal conductive carbon fiber 2, it is conducted to the polymer matrix material 4 and then through the thermally conductive filler 3 to the polymer. Conducts through the matrix material 4.

  The route passing from (3) to (4) in the figure; after conducting through the high thermal conductive carbon fiber 2 in the fiber direction, the high thermal conductive carbon fiber 2 adjacent through the polymer matrix material 4 and the thermal conductive filler 3 Conducts in the fiber direction.

  A route passing from (2) to (4) in the figure; after conducting in the polymer matrix material 4 through the heat conductive filler 3, it is conducted to the high thermal conductivity carbon fiber 2 and conducted in the fiber direction.

  As described above, the addition of the heat conductive filler 3 in the polymer matrix material 4 not only increases the heat conduction in the polymer matrix material 4 which is not inherently high in thermal conductivity, but also inherently in the fiber direction. Compared with this, heat conduction in the direction perpendicular to the low fibers is also promoted. As a result, the thermal conductivity in the fiber direction is greatly improved as compared with the case where the polymer matrix material is simply impregnated with the high thermal conductivity carbon fiber. Note that some heat conduction paths are conducted in the direction perpendicular to the fiber direction of the carbon fiber, and finally radiated. However, the heat conductivity is much smaller than that in the fiber direction, and is shown in the figure. Absent.

  The raw material which comprises the high heat conductive composite material by this invention is demonstrated.

(A) Carbon fiber aligned in one direction The carbon fiber is not particularly limited, and a PAN-based (PAN: polyacrylonitrile), pitch-based or other known carbon fiber having a high thermal conductivity is appropriately selected. Can be used. In particular, it is preferable to use pitch-based carbon fibers (thermal conductivity> 300 W / mK) that are excellent in thermal conductivity.

  From this viewpoint, the thermal conductivity of the carbon fiber is preferably 300 W / mK or more, more preferably 500 W / mK or more. In addition, although it does not restrict | limit in particular regarding an upper limit, the thing of about 600 W / mK has been developed and such a thing can also be used. However, the thermal conductivity of the carbon fiber can be used if it is about 200 W / mK depending on the intended use. That is, in the present invention, as shown in Table 1 to be described later, an excellent thermal conductivity as a composite material can be expressed without losing the high thermal conductivity of the carbon fiber as much as possible. This is because it can.

  The fiber diameter of the carbon fiber is not particularly limited, and may be determined in consideration of the required strength and the like according to the purpose of use, and a fiber having an arbitrary thickness is used according to the purpose. be able to. Preferably about 5-10 micrometers is used.

  The blending amount of the carbon fiber may be appropriately selected according to the thermal conductivity of the carbon fiber alone to be used and the thermal conductivity aimed for as the heat conductive composite material, but the volume content is 40% to 70%, preferably 55 to 55%. 65%. When the amount of carbon fiber is less than 40% in volume content, there are many low thermal conductive resin parts (polymer matrix material), so the thermal conductivity of the whole material is lowered and heat cannot be sufficiently dissipated. There is a fear. On the other hand, when the blending amount of the carbon fiber exceeds 70% in volume content, a molded body cannot be formed, and physical or mechanical strength is lowered, and there is a possibility that it is cracked or broken.

  Moreover, a part of the carbon fibers aligned in one direction may be oriented in another direction without being aligned in one direction. This is because there is no problem in the path for dispersing heat shown in FIG. 2 even if a part extends in a direction other than the fiber direction (for example, the width direction). Preferably, it is desirable that the entire carbon fibers are aligned in one direction because the thermal conductivity can be increased. That is, when the carbon fibers are aligned in one direction, heat is conducted in the direction in which the carbon fibers are aligned as shown in FIG. 2, and the heat conduction in the direction perpendicular to the carbon fibers is small. Therefore, the carbon fiber aligned in one direction of the highly heat-conductive material of the present invention is continuous over both ends of the material, and as shown in FIG. 2, the end surface of one end generates heat like an electronic component of an electronic device. It is desirable to arrange it so as to face the body. In the present invention, carbon fibers aligned in one direction may be impregnated into a polymer matrix material containing a thermally conductive filler to form a prepreg, and after impregnation, the carbon fiber is molded and cured into a desired shape. A molding material may be used, and if necessary, this may be cut in a direction orthogonal to the fiber direction of the carbon fiber so that the end of the carbon fiber is exposed at the cut end. In the present invention, for the purpose of improving the strength and adhesiveness of the end portion of the molding material, an appropriate coating material (such as an appropriate adhesive material) may be coated to form a thin film. This is not excluded.

(B) Polymer Matrix Material As the polymer matrix material, a generally known thermosetting resin or thermoplastic resin can be appropriately selected and used according to the intended use. Among these, examples of the thermosetting resin include epoxy resin, polyimide resin, bismaleimide resin, unsaturated polyester resin, vinyl ester resin, phenol resin, polyamide resin, urea resin, silicone resin, urethane resin, and the like. Examples of the thermoplastic resin include polyethylene resin and polypropylene resin. From the viewpoint of mechanical properties, carbon fiber impregnation, moldability, heat resistance, adhesion to fibers, and the like, an epoxy resin is preferred.

  As the high thermal conductive material, a so-called prepreg in which carbon fibers aligned in one direction are pre-impregnated in a polymer matrix material such as an epoxy resin can be used. The prepreg means impregnation in advance. In the present invention, the prepreg is an intermediate material for molding in which a carbon fiber aligned in one direction is impregnated with a resin (polymer matrix material). In general, a composite material can be obtained by heating and curing a laminate of this prepreg and winding. Furthermore, a prepreg made of a thermoplastic resin using a thermoplastic resin can also be used.

  The highly heat-conductive material of the present invention can be used as a molded composite material (also simply referred to as a molding material or a high heat-conductive composite material) such as a material for heat dissipation / heat conduction in electronic equipment or a housing material for electronic equipment. In addition to lightweight, high-strength composite materials with excellent strength, intermediate molding materials such as the above-mentioned prepreg used for molding materials such as heat dissipation and heat conduction materials in electronic devices and housing materials for electronic devices Materials are also included.

  The blending amount of the polymer matrix material is 22 to 45% by volume, preferably 26 to 34% by volume. If the amount of the polymer matrix material is less than 22% by volume, the physical or mechanical strength may be reduced, and there is a risk of cracking or breakage. If it exceeds 45% by volume, the thermal conductivity is reduced. The desired thermal conductivity may not be obtained.

(C) Thermally conductive filler In the present invention, the polymer matrix material newly contains a thermally conductive filler. Examples of the thermally conductive filler include aluminum oxide, boron nitride, silicon nitride, silicon carbide, etc., which are usually excellent in thermal conductivity, carbon short fibers, graphitized carbon, etc. Is preferred.

  The shape of the aluminum oxide powder is preferably spherical because it is non-spherical and has poor dispersibility in the matrix material. In addition, regarding the shape of the other thermally conductive filler, since non-spherical shape has poor dispersibility in the matrix material, it is preferably spherical. Here, the term “spherical” refers to particles having an average circularity of 0.4 or more, more preferably 0.8 or more, which form the powder. Here, the circularity is defined by, for example, connecting edge points of the binarized particle image with the particle projection image as defined in the flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. When the length of the obtained outline is (A) and the perimeter of the equivalent circle is (B), it is expressed by (B) / (A).

  The average spherical diameter of the spherical heat conductive filler is preferably 1 to 35 μm, and more preferably 3 to 10 μm. If it is less than 1 μm or exceeds 35 μm, the dispersibility in the matrix material is poor, and if it is less than 1 μm, the cost also increases.

  The compounding quantity of the said heat conductive filler is 7-15 volume%, Preferably it is 9-11 volume%. When the blending amount of the heat conductive filler is less than 7% by volume, the thermal conductivity is not improved so much, and when it exceeds 15% by volume, the dispersibility of the filler in the matrix material is deteriorated.

  In addition to the essential components (a) to (c) described above, the high thermal conductive material of the present invention may appropriately include other components as long as it does not affect the effects of the present invention. . Moreover, the sum total of the compounding quantity of the structural component of the high heat conductive material of this invention is 100 volume%.

  Next, the use of the high thermal conductive material of the present invention will be described below with reference to the drawings.

  FIG. 3 schematically shows an example of the orientation of the carbon fibers in the high heat conductive composite material when the high heat conductive composite material according to the present invention is used as a heat dissipation / heat conductive material or housing material for electronic equipment. FIG. FIG. 4 shows a case where the high heat conductive composite material according to the present invention is formed into a sheet shape, and is superposed by stacking (stacking) sequentially so that the fiber directions of the carbon fibers in the high heat conductive composite sheet material intersect. It is the schematic which represented typically one example of the mode of orientation of each carbon fiber in a high heat conductive composite sheet laminated material and each high heat conductive composite sheet material when it was set as the conductive composite sheet laminated material.

  As shown in FIG. 2, the high thermal conductivity material of the present invention is formed by disposing one end side 1 a of carbon fibers aligned in one direction as a material for heat dissipation / heat conduction in an electronic device or a housing material for an electronic device. By disposing the heat generating element 5 in the vicinity of the heat generating element 5 such as an electronic component in the apparatus (more preferably, disposing the other end 1b of the carbon fiber so as to face the outside 6 of the electric apparatus), The generated heat can be conducted to the outside 6 of the electronic device along the heat conduction path shown in FIG. 2 and efficiently radiated.

  Therefore, for example, when used as a material for heat dissipation / heat conduction in an electronic device or a housing material for an electronic device, as shown in FIG. 3, the fiber direction of the carbon fiber in the high heat conduction material 33 (see FIG. The high heat conductive material 33 is indicated by a solid line 33a) from the heating element 32 of an electronic component or the like (for example, CPU) mounted on the printed circuit board 31 in the electronic device through the casing 34 of the electronic device. In order to increase both the thermal conductivity and the mechanical strength, it is desirable to orient at an angle to the outside 35 of the device. Here, the fiber direction of the carbon fibers in the high heat conductive material 33 is obliquely arranged as long as a part or all of the entire path from the heating element 32 to the outside 35 of the electronic device is inclined. . In such electronic devices, electronic components are often mounted on the printed circuit board at high density from the viewpoint of reduction in size and weight. In such a case, in order to accommodate the highly heat-conductive material in the electronic device, it is preferable to use a film having flexibility so that it can be packed in a limited gap. Even in such a case, as described above with reference to FIG. 2, it is possible to form heat conduction paths (five paths shown in FIG. 2) from the heating element to the casing of the device (and thus the outside). Thus, it can be said that it is sufficient that the carbon fibers aligned in one direction are continuous from the heating element to the casing (and thus the outside) of the device. That is, it is possible to maintain the various heat conduction paths described with reference to FIG. 2 without any problem even if the highly heat-conductive material sheet or film is curved or twisted by a component in the electronic device during the process. Yes, it can transfer the heat received from the heating element and effectively radiate it outside the electronic device. In addition, in FIG. 3, although the highly heat-conductive material sheet | seat thru | or film of the composite material which shape | molded the carbon fiber of the single layer or multiple layers arranged in one direction is represented, in this invention, what is restrict | limited to this aspect at all is not. For example, it goes without saying that the same effect can be obtained even when a highly heat-conductive material sheet or multilayer film of a composite material formed by multilayer molding as shown in FIG. 4 is used. This is because in addition to the upper and lower surfaces of the housing of the electronic device, the side surfaces thereof can be effectively utilized to dissipate heat. For example, in addition to phone / email transmission / reception functions, in addition to megapixel digital camera functions, video functions, high-speed Internet connection functions that can support video transmission / reception, digital TV reception functions, GPS functions, etc. Numerous functions are packed, such as high capacity with a small hard desk. For this reason, in such electronic devices, ultra-high-density mounting is being promoted by using a multilayer printed circuit board or multilayer mounting on a printed circuit board. Along with this, the number of parts that become heating elements (built-in batteries and hard desks can also become heating elements through continuous use) increases, or the super-high performance of the parts that become heating elements (for example, the CPU) itself The amount of heat generated tends to increase as a result of the conversion. In such a case, a highly heat-conductive material sheet or a multilayer film that exhibits the above effects can be used effectively.

  Further, in the present invention, a material having a large heat radiation area, such as a housing material for an electronic device, can be used to radiate heat more effectively as shown in FIG. Are formed into a sheet shape (or film shape), and the fiber directions of the carbon fibers in these sheet materials (or film materials) 41 and 42 (sheet materials 41 and 42). In order to intersect with each other at a certain angle (shown as solid lines 41a and 42a) (in FIG. 4, an example of intersecting with an angle of 90 degrees is shown) It is good also as a desired high heat conductive composite sheet laminated material 43 by laminating | stacking and shape | molding. Alternatively, one layer or multiple layers of carbon fibers aligned in one direction in advance and one layer or multiple layers of carbon fibers aligned in one direction at a certain angle are stacked on top of each other to form multiple layers. Materials may be used. Also at this time, at least one layer of carbon fibers in the multilayered sheet material (or film material) forms a heat conduction path as shown in FIGS. 2 and 3 from the heating element to the outside of the electronic device. Further, they may be aligned and oriented (see FIG. 3).

  Furthermore, in the high thermal conductive composite sheet laminated material laminated in multiple layers, a new path similar to the thermal conduction path via (3) to (4) in FIG. 2 is formed. For example, if it demonstrates using the highly heat-conductive composite sheet laminated material 43 shown in FIG. 4, the heat received from heat generating bodies (not shown; refer to FIG. 2) such as electronic components in the electronic device will generate heat at one end. After conducting in the fiber direction 41a in the high thermal conductivity composite sheet material 41 (one or more layers of carbon fibers aligned in one direction) connected to the body, the polymer matrix material 41b in the sheet material 41, thermal conductivity Through a filler (not shown; see FIG. 2), it conducts in the fiber direction 42a through the adjacent high thermal conductive composite sheet material 42 (one or more layers of carbon fibers aligned in another direction). By such heat conduction, heat sequentially propagates in the sheet material stacking direction to form a new heat conduction path. Thereby, in addition to the upper and lower surfaces of the housing of the electronic device, the side surfaces thereof can be effectively utilized to dissipate heat. Similarly, a new path similar to the path heat conduction path via (2) to (4) in FIG. 2 is formed. For example, if it demonstrates using the highly heat-conductive composite sheet laminated material 43 shown in FIG. 4, the heat received from heat generating bodies (not shown; refer to FIG. 2) such as electronic components in the electronic device will generate heat at one end. Thermally conductive filler (not shown; see FIG. 2) in the polymer matrix material 41b in the high thermal conductive composite sheet material 41 (one or more layers of carbon fibers aligned in one direction) connected to the body Then, it is conducted to the adjacent high thermal conductive composite sheet material 42 (one or more layers of carbon fibers aligned in one direction) and conducted to the fiber direction 42a. Also by such heat conduction, heat sequentially propagates in the sheet material lamination direction to form a new heat conduction path. Also by this, in addition to the upper surface and the lower surface of the casing of the electronic device, the side surface portion can be effectively used to dissipate heat.

  In these cases, the lamination of the sheet material may be performed by forming each layer and then joining with an adhesive or the like. However, using a prepreg for each sheet material, these are sequentially laminated (under pressure if necessary) ) Heat curing may be used. By carrying out like this, since joining between each sheet material becomes strong, it is preferred.

  Such a highly heat conductive material such as a sheet material can be bonded by bonding with an adhesive or by fusing using ultrasonic waves. An adhesive is used for the adhesion, but it is preferable to use a heat conductive adhesive containing alumina, carbon, silver or the like. In addition, when connecting this high heat conductive material to a heat generating body, a housing | casing, etc., it can join by adhere | attaching by adhesion | attachment with an adhesive agent, or an ultrasonic wave. In this case as well, an adhesive is used for bonding, but it is preferable to use a heat conductive adhesive containing alumina, carbon, silver, or the like.

  As for the use of the highly heat-conductive material of the present invention, as described above, in addition to electronic devices incorporating electronic components, particularly laptop computers, mobile phones and portable information terminals suitable for mobile or ubiquitous, DVD recorders and DVDs Materials for heat dissipation and heat conduction in electronic devices such as players (including air cooling system materials), housing materials for electronic devices, DVD optical pickup base materials such as DVD recorders and players, and air cooling fan outer frame materials .

  Next, the present invention will be described more specifically with reference to examples and comparative examples.

Examples 1-3 and Comparative Examples 1-7
As the carbon fibers, two types (310 W / mK, 500 W / mK) of high thermal conductivity pitch-based carbon fibers (for example, manufactured by Nippon Graphite Fiber Co., Ltd.) having different thermal conductivities were used. As the heat conductive filler, spherical aluminum oxide (for example, manufactured by Micron Corporation) powder having an average particle diameter of 3 μm was used. Epoxy resin was used as the polymer matrix material.

  First, 50% by weight of aluminum oxide is added to the epoxy resin. A prepreg was prepared using the carbon fibers aligned in one direction with this. Next, the obtained prepreg was laminated and cured by applying pressure and temperature in an autoclave.

  As shown in Table 1, the blending amount of carbon fiber in each sample of the obtained high heat conductive material is 55% (Examples 1 and 2, Comparative Examples 1 and 2) to 62% (Example 3). ).

  Moreover, the compounding quantity of the polymer matrix material (epoxy resin) in each sample of the obtained high heat conductive material is 34 volume% (Examples 1 and 2), 28.5 volume% (Example 3), 45 volume. % (Comparative Examples 1 and 2), and the amount of heat conductive filler (aluminum oxide powder) was 11 volume% (Examples 1 and 2), 9.5 volume% (Example 3), and 0 volume%. (Comparative Examples 1 and 2).

  Table 1 shows the results of measurement of thermal conductivity and specific gravity using each sample of the high thermal conductivity material. The thermal conductivity was measured by a laser flash method. In the table, for comparison, as Comparative Examples 3 to 7, numerical values of three kinds of high heat conductive metals, aluminum oxide alone, and high heat conductive resin PPS (polyphenylene sulfide) are also listed.

  According to this result, as in Examples 2 and 3, by using a carbon fiber having a thermal conductivity of 500 W / mK and further adding an appropriate amount of aluminum oxide powder as a thermal conductive filler, Thermal conductivity of 1.3 to 1.4 times that of certain aluminum (Comparative Example 4) and 760 to 850 times that of typical high thermal conductive resin PPS (Comparative Example 7) was obtained. In general, it is known that the thermal conductivity of a composite material composed of two kinds of materials is based on a composite rule of λ = V (1) λ (1) + V (2) λ (2). Here, λ is the thermal conductivity, V is the volume fraction, and the numbers in () represent the materials constituting the composite material. In Examples 1 to 3 of Table 1 to which aluminum oxide powder was added as a heat conductive filler, the thermal conductivity of the epoxy resin which is a polymer matrix material was 0.26 W / mK, which is extremely higher than that of carbon fiber and aluminum oxide. Since it is small, the thermal conductivity can be regarded as a composite material composed of two kinds of materials.

  Therefore, assuming that the thermal conductivity of the high thermal conductive composite material of the present invention follows the above composite rule, the thermal conductivities of Examples 1 to 3 are 179 W / mK, 283 W / mK, and 318 W / mK, respectively. However, as shown in Table 1, the actual measurement value greatly exceeds that. Moreover, when compared with Comparative Examples 1 and 2 to which no aluminum oxide was added, the thermal conductivity could be improved by 55 W / mK. This is a value far exceeding the thermal conductivity of aluminum oxide alone (36 W / mK), and the presence of aluminum oxide promotes the heat conduction between carbon fibers and, in turn, the heat conduction in the fiber direction of the carbon fibers. It can be seen that the thermal conductivity is much higher. On the other hand, the specific gravity was 2/3 that of aluminum, which was as light as a resin.

It is the cross-sectional schematic which represented typically one Embodiment of the structure of the high heat conductive (composite) material by this invention. FIG. 1A is a schematic view showing a section cut along a plane perpendicular to the direction of carbon fibers aligned in one direction, and FIG. 1B is a plane parallel to the carbon fiber direction. FIG.1 (c) is an expanded sectional view of one carbon fiber aligned in one direction in Fig.1 (a). It is the cross-sectional schematic which represented typically the example of the heat conduction path | route how heat is conducted in the high heat conductive composite material in this invention. A cross section schematically showing an example of the orientation of carbon fibers in a high heat conductive composite material when the high heat conductive composite material in the present invention is used as a heat dissipation / heat conductive material or a housing material of an electronic device. FIG. The highly heat-conductive composite material according to the present invention is formed into a sheet shape, and the high-heat-conductive composite sheet is laminated by stacking (stacking) sequentially so that the fiber directions of the carbon fibers in the high heat-conductive composite sheet material intersect. It is the schematic which typically represented one example of the mode of orientation of each carbon fiber in a high heat conductive composite sheet laminated material and each high heat conductive composite sheet material when it was set as material.

Explanation of symbols

1 High thermal conductivity materials,
1a One end side of carbon fibers aligned in one direction,
1b The other end of the carbon fibers aligned in one direction,
2 High thermal conductivity carbon fiber,
2a carbon fiber filament,
3 thermally conductive filler,
4 polymer matrix material,
5 heating element,
6 Outside of electronic equipment,
31 Printed circuit board,
32 heating elements (CPU etc.),
33 High thermal conductivity materials,
33a Fiber orientation of carbon fibers aligned in one direction,
34 Electronic equipment housing,
35 Outside electronic equipment,
41, 42 High thermal conductivity composite sheet material,
41a, 42a Fiber directions of carbon fibers aligned in one direction,
41b polymer matrix material,
43 High thermal conductivity composite sheet laminate material.

Claims (8)

  A highly thermally conductive material characterized in that carbon fibers aligned in one direction are contained in a polymer matrix material, and further, a thermally conductive filler is contained in the polymer matrix material.   The high thermal conductivity material according to claim 1, wherein the carbon fiber has a thermal conductivity of 300 W / mK or more.   The high heat conductive material according to claim 1 or 2, wherein the heat conductive filler is an aluminum oxide powder having an average particle size of 1 to 35 µm.   The shape of the said heat conductive filler is spherical shape, The high heat conductive material of any one of Claims 1-3 characterized by the above-mentioned.   The high thermal conductive material according to claim 1, which is a molding intermediate material or a molded composite material.   One or more layers of carbon fibers aligned in one direction have a certain angle, and one or more layers of carbon fibers aligned in another direction are alternately stacked to form a multilayer. The highly heat-conductive material according to any one of claims 1 to 5.   7. One end of carbon fiber aligned in one direction in the high thermal conductivity material which is the molded composite material according to claim 1-5, or high thermal conductivity which is the multilayer molded composite material according to claim 6. An electronic device characterized in that one end of a certain layer of carbon fibers aligned in one direction in the material is oriented toward an electronic component that generates heat in the device.   The electronic device according to claim 7, wherein the high heat conductive material is used as a material for heat dissipation / heat conduction in the electronic device and / or a housing material for the electronic device.

Images