Method for producing thermally conductive molded body

Abstract

The present invention provides a method for manufacturing a thermally conductive molded body having a high-density carbon fiber bundle and a high thermal conductivity coefficient. The method comprises: preparing a carbon fiber bundle (2) filled with a resin liquid; inserting the carbon fiber bundle (2) filled with a resin liquid (3) into a shrinkable tube (5) and shrinking the tube (5); and solidifying the resin liquid (3) filled between the carbon fibers.

Description

Technical Field

[0001] The present technology relates to a method for producing a thermally conductive molded body that is disposed between a heat generating portion and a heat dissipating component inside an electronic device to promote heat dissipation. Background Art

[0002] In recent years, electronic devices have become increasingly smaller, but their power consumption has not changed as expected due to the diversity of their applications. As a result, more attention has been paid to heat dissipation measures within the devices.

[0003] As heat dissipation countermeasures in the above-mentioned electronic devices, heat sinks, heat pipes or heat sinks made of metal materials with high thermal conductivity such as copper and aluminum are widely used. These heat dissipation components with excellent thermal conductivity are arranged in a manner close to electronic components such as semiconductor packages that are heat generating parts in electronic devices in order to achieve heat dissipation effects or temperature relaxation in the device. In addition, these heat dissipation components with excellent thermal conductivity are arranged in a range from electronic components that are heat generating parts to low temperature locations.

[0004] Heat-conducting sheets and heat-conducting grease are used in heat-generating parts of electronic devices. For example, Patent Document 1 discloses a technology of a heat-conducting sheet used between a semiconductor such as a CPU and a heat sink.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-35580

[0008] In such a thermally conductive sheet, a fibrous thermally conductive filler is often used as a thermally conductive medium for conducting heat from a heat generating portion to a heat dissipating component, and among these, thermally conductive sheets using carbon fibers are widely used.

[0009] Carbon fiber has high thermal conductivity and excellent heat dissipation, but when it is made into a carbon fiber bundle, it has poor flexibility and may be entrained with air bubbles when the binder resin is filled by capillary action. When air bubbles are entrained between carbon fibers, a high-density carbon fiber bundle cannot be formed, which may hinder heat conduction. Summary of the invention

[0010] Therefore, an object of the present technology is to provide a method for producing a thermally conductive molded body having a high-density carbon fiber bundle and a high thermal conductivity.

[0011] Solutions for solving problems

[0012] In order to solve the above-mentioned problems, the manufacturing method of the thermally conductive molded body of the present technology includes: a process of preparing a carbon fiber bundle filled with a resin liquid; a process of inserting the carbon fiber bundle filled with the above-mentioned resin liquid into a shrinkable tube and shrinking the above-mentioned tube; and a process of solidifying the above-mentioned resin liquid filled between the above-mentioned carbon fibers.

[0013] Effects of the Invention

[0014] According to the present technology, by shrinking the shrinkable tube, the excess resin liquid in the resin liquid filled between the carbon fibers can be squeezed out. Then, by solidifying the resin liquid in the solidification step after squeezing out the excess resin liquid, the sheet shape is maintained by the resin liquid filled and solidified between the carbon fibers, and the excess resin liquid is removed, so that a thermally conductive molded body and a thermally conductive sheet in which the carbon fibers are densely filled can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a perspective view showing the appearance of a part of a thermally conductive molded body to which the present technique is applied.

[0016] Figure 2 This is a cross-sectional view showing an example of a semiconductor device using a thermally conductive sheet.

[0017] Figure 3 This is a diagram showing a process of immersing a carbon fiber bundle in a resin liquid to impregnate carbon fibers with the resin liquid.

[0018] Figure 4 This is a diagram showing the process of making a carbon fiber bundle by immersing carbon fiber yarns in a resin solution.

[0019] Figure 5 This is a diagram showing the step of inserting a carbon fiber bundle impregnated with a resin liquid into a shrinkable tube.

[0020] Figure 6 This is a perspective view showing a step of obtaining a thermally conductive sheet by slicing a thermally conductive molded body.

[0021] Figure 7 This is a perspective view showing the appearance of a shrinkable tube having holes formed on the outer peripheral surface.

[0022] Figure 8 This is an external perspective view showing a step of sandwiching a mesh member between a tube and a carbon fiber bundle.

[0023] Fig. 9 This is a side view showing a state where the carbon fiber bundle is inserted into a plurality of tubes shorter than the carbon fiber bundle.

[0024] Description of reference numerals:

[0025] 1: carbon fiber, 2: carbon fiber bundle, 3: resin liquid, 5: tube, 10: thermally conductive molded body, 11: thermally conductive sheet. DETAILED DESCRIPTION

[0026] Hereinafter, the manufacturing method of the thermally conductive molded body using the present technology will be described in detail with reference to the accompanying drawings. It should be noted that the present technology is not limited to the following embodiments, and various changes can be made without departing from the main purpose of the present technology. In addition, the accompanying drawings are schematic, and the ratios of various dimensions are sometimes different from the actual ones. The specific dimensions should be determined with reference to the following description. In addition, of course, the drawings also contain parts with different dimensional relationships and ratios.

[0027] [Thermal conductive molded body]

[0028] like Figure 1 As shown in FIG. 1 , a thermally conductive molded body 10 to which the present technology is applied is formed by solidifying a resin liquid 3 filled between carbon fibers of a carbon fiber bundle 2. In the thermally conductive molded body 10, carbon fibers 1 are densely filled and are integrated by the solidified resin liquid. The thermally conductive molded body 10 is sliced ​​into sheets and used as a thermally conductive sheet 11 sandwiched between a heat source and a heat dissipation member of a semiconductor device or the like (see FIG. 1 ). Figure 2 ).

[0029] The method for manufacturing a thermally conductive molded body using the present technology includes: Figure 3 , Figure 4 As shown, the process of preparing a carbon fiber bundle filled with resin liquid; Figure 5 As shown, the process includes inserting the carbon fiber bundle 2 filled with the resin liquid 3 into the shrinkable tube 5 and shrinking the tube 5; and curing the resin liquid 3 filled between the carbon fibers.

[0030] like Figure 3 As shown in (A) to (C) of FIG. 1 , a carbon fiber bundle filled with a resin liquid can be formed by preparing a carbon fiber bundle 2 in which a plurality of carbon fibers 1 are oriented in the same direction and bundled, and filling the spaces between the carbon fibers of the carbon fiber bundle 2 with a resin liquid 3 .

[0031] In addition, if Figure 4 As shown in (A) and (B), a carbon fiber bundle filled with resin liquid can be formed by a step of immersing carbon fiber 1 in resin liquid 3 and a step of forming a carbon fiber bundle 2 in which the carbon fibers 1 immersed in the resin liquid 3 are oriented in the same direction and bundled.

[0032] [Carbon Fiber]

[0033] The carbon fiber 1 contained in the thermally conductive sheet 11 of the present invention is oriented in a manner throughout the thickness direction of the sheet and is a material that bears thermal conductivity. There is no particular restriction on the type of carbon fiber 1, and it can be appropriately selected according to the purpose. For example, asphalt-based, PAN-based, carbon fibers that graphitize PBO fibers, and carbon fibers synthesized by arc discharge, laser evaporation, CVD (chemical vapor deposition), CCVD (catalytic chemical vapor deposition), etc. can be used. Among them, from the viewpoint of obtaining high thermal conductivity, carbon fibers that graphitize PBO fibers and asphalt-based carbon fibers are more preferred.

[0034] In addition, the carbon fiber 1 may be used after a part or all of it has been subjected to surface treatment as required. Examples of the surface treatment include oxidation treatment, nitridation treatment, nitration treatment, sulfonation treatment, or treatment of attaching or bonding metals, metal compounds, organic compounds, etc. to the functional groups introduced to the surface by these treatments or to the surface of the carbon fiber. Examples of the functional groups include hydroxyl groups, carboxyl groups, carbonyl groups, nitro groups, amino groups, etc.

[0035] The carbon fiber 1 is preferably formed by twisting a plurality of carbon fibers together to form a thin and long filamentary carbon fiber filament. Alternatively, the carbon fiber 1 may be formed by twisting a plurality of carbon fiber filaments together to form a longer and stronger carbon fiber filament. In the method for manufacturing a thermally conductive molded body using the present technology, Figure 3 As shown in (A) to (C), such a bundle of carbon fibers or carbon fiber yarns is prepared, and the carbon fiber bundle 2 is immersed in a resin liquid 3 described later to fill the spaces between the carbon fibers with the resin liquid 3. The carbon fiber bundle 2 is integrated by solidifying the resin liquid 3 filled between the carbon fibers.

[0036] In addition, the method for producing a thermally conductive molded body using the present technology can be as follows: Figure 4 As shown in (A) and (B) of , a carbon fiber bundle filled with resin liquid 3 is formed by a process of immersing carbon fiber 1 in resin liquid 3 and a process of forming carbon fiber bundle 2 in which carbon fiber 1 immersed in resin liquid 3 is oriented in the same direction and bundled. After immersing carbon fiber 1 in resin liquid 3 to make it adhere, a carbon fiber bundle 2 in which carbon fiber 1 is oriented in the same direction and bundled is formed, and a carbon fiber bundle 2 in which the resin liquid 3 is filled inside the carbon fiber bundle 2 can be obtained. The carbon fiber 1 immersed in the resin liquid 3 can be a slender filamentary carbon fiber filament formed by twisting a plurality of carbon fibers, or a longer and stronger carbon fiber filament formed by twisting a plurality of carbon fiber filaments. The carbon fiber bundle 2 is integrated by solidifying the resin liquid 3 filled between the carbon fibers.

[0037] It should be noted that the length of the carbon fiber bundle 2 is not particularly limited and can be appropriately selected, and can be set to a range of 3 cm to 100 cm as an example.

[0038] [Resin liquid]

[0039] The resin liquid 3 filled between the carbon fibers of the carbon fiber bundle 2 is a binder resin that binds the densely filled carbon fibers 1 to maintain the sheet shape of the thermally conductive sheet 11. The resin liquid 3 has a polymer matrix component and may contain an inorganic filler and other components as appropriate.

[0040] There is no particular limitation on the type of the polymer matrix component contained in the thermally conductive sheet 11, and a known polymer matrix component can be appropriately selected. For example, a thermosetting polymer can be cited as one of the polymer matrix components.

[0041] As the thermosetting polymer, for example, crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenolic resin, unsaturated polyester, diallyl phthalate resin, silicone resin, polyurethane, polyimide silicone, thermosetting polyphenylene ether, thermosetting modified polyphenylene ether, etc. can be listed. These can be used alone or in combination of two or more.

[0042] It should be noted that, as the cross-linked rubber, for example, natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, fluororubber, urethane rubber, acrylic rubber, polyisobutylene rubber, silicone rubber, etc. can be listed. These can be used alone or in combination of two or more.

[0043] Among these thermosetting polymers, silicone resin is preferably used from the viewpoints of excellent molding processability and weather resistance and good adhesion and conformability to electronic components. The silicone resin is not particularly limited, and the type of silicone resin can be appropriately selected according to the purpose.

[0044] From the viewpoint of obtaining the above-mentioned molding processability, weather resistance, and tight adhesion, the silicone resin is preferably a silicone resin composed of a main agent of liquid silicone gel and a curing agent. As such silicone resins, for example, addition reaction type liquid silicone resins, heat-curable millable silicone resins using peroxide for vulcanization, etc. can be cited. Among them, as a heat dissipation component of an electronic device, the heat-generating surface of the electronic component and the heat sink surface are required to have tight adhesion, so addition reaction type liquid silicone resins are particularly preferred.

[0045] As the addition reaction type liquid silicone resin, it is preferable to use a two-component addition reaction type silicone resin containing polyorganosiloxane having a vinyl group as a main agent and polyorganosiloxane having a Si—H group as a curing agent.

[0046] In addition, the content of the polymer matrix component and the inorganic filler and other components appropriately contained in the thermal conductive sheet 11 is not particularly limited and can be appropriately selected according to the purpose. From the perspectives of achieving high-density filling of the carbon fibers 1, ensuring high thermal conductivity, discharging the remaining resin liquid 3 contained between the carbon fibers with the shrinkage strength of the shrinkable tube 5, bonding the carbon fibers to maintain the sheet shape after the resin liquid 3 is cured, and ensuring the adhesion of the sheet, it is preferably about 10% to 50% by volume. That is, it is preferred that the thermal conductive sheet 11 contain 50 to 90% by volume of carbon fibers.

[0047] [Thermal conductive filler]

[0048] To further improve thermal conductivity, the thermally conductive sheet 11 may contain other thermally conductive fillers. The type of thermally conductive filler is not particularly limited as long as it is a material with high thermal conductivity, and examples thereof include metals such as silver, copper, and aluminum, and ceramics such as alumina, aluminum nitride, silicon carbide, and graphite.

[0049] It should be noted that the thermally conductive filler may be used alone or in combination of two or more. In addition, when two or more thermally conductive fillers are used, they may all be fibrous thermally conductive fillers, or a fibrous thermally conductive filler and a thermally conductive filler of another shape may be used in combination.

[0050] [Inorganic fillers]

[0051] The thermally conductive sheet 11 may further contain an inorganic filler. By containing an inorganic filler, the thermal conductivity of the thermally conductive sheet 11 can be further improved, and the strength of the sheet can be improved. As the inorganic filler, there is no particular restriction on the shape, material, average particle size, etc., and it can be appropriately selected according to the purpose. As the shape, for example, spherical, elliptical, blocky, granular, flat, needle-shaped, etc. can be listed. Among them, from the perspective of filling, spherical and elliptical shapes are preferred, and spherical shapes are particularly preferred.

[0052] As the material of the inorganic filler, for example, aluminum nitride (AlN), silicon dioxide, aluminum oxide (aluminum oxide), boron nitride, titanium dioxide, glass, zinc oxide, silicon carbide, silicon (silicon), silicon oxide, metal particles, etc. can be listed. These can be used alone or in combination of two or more. Among them, aluminum oxide, boron nitride, aluminum nitride, zinc oxide, and silicon dioxide are preferred. In terms of thermal conductivity, aluminum oxide and aluminum nitride are particularly preferred.

[0053] In addition, the inorganic filler may be a surface-treated inorganic filler. When the inorganic filler is treated with a coupling agent as the surface treatment, the dispersibility of the inorganic filler is improved, and the flexibility of the thermally conductive sheet is improved.

[0054] The average particle size of the inorganic filler can be appropriately selected according to the type of inorganic material. When the inorganic filler is alumina, the average particle size is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm, and particularly preferably 4 μm to 5 μm. When the average particle size is less than 1 μm, the viscosity increases and it may become difficult to mix. On the other hand, when the average particle size exceeds 10 μm, the thermal resistance of the thermal conductive sheet may increase.

[0055] Furthermore, when the inorganic filler is aluminum nitride, the average particle size is preferably 0.3 μm to 6.0 μm, more preferably 0.3 μm to 2.0 μm, and particularly preferably 0.5 μm to 1.5 μm. When the average particle size is less than 0.3 μm, the viscosity becomes high and may become difficult to mix. When the average particle size exceeds 6.0 μm, the thermal resistance of the thermal conductive sheet may become high.

[0056] It should be noted that the average particle size of the inorganic filler can be measured by, for example, a particle size distribution meter or a scanning electron microscope (SEM).

[0057] [Other ingredients]

[0058] In addition to the above-mentioned polymer matrix component and inorganic filler, the thermal conductive sheet 11 may also contain other components as appropriate according to the purpose. As other components, for example, magnetic metal powder, thixotropy imparting agent, dispersant, curing accelerator, retarder, slight viscosity imparting agent, plasticizer, flame retardant, antioxidant, stabilizer, colorant, etc. can be listed.

[0059] These polymer matrix components and appropriately contained inorganic fillers and other components are mixed to prepare resin liquid 3. It should be noted that there is no particular limitation on the steps of mixing the components for preparation, and for example, the resin liquid 3 can be prepared by adding inorganic fillers, magnetic metal powder, and other components to the polymer matrix component and mixing them.

[0060] [Tube]

[0061] The shrinkable tube 5 into which the carbon fiber bundle 2 filled with the resin liquid 3 is inserted is formed of a material that can shrink by heating and its own tension. The tube 5 shrinks after the carbon fiber bundle 2 is inserted, and squeezes out the excess resin liquid 3 in the resin liquid 3 filled between the carbon fibers.

[0062] The shape of the tube 5 may be any tubular shape having an opening for inserting the carbon fiber bundle 2, but a cylindrical shape is preferred because the pressure due to contraction is evenly applied to the carbon fiber bundle 2.

[0063] As the material of the heat shrinkable tube 5, for example, a known material such as vinyl chloride, silicone rubber, fluorine-based polymer, polyolefin resin, etc. can be used.

[0064] The heat treatment of the tube 5 can be performed by a known method such as an oven, a belt conveyor oven, a gas torch, an industrial dryer, etc. Here, the heat shrinkable tube 5 needs to shrink before the resin liquid 3 filled between the carbon fibers is solidified. This is because if the resin liquid 3 solidifies first, the shrinkage of the tube 5 will be hindered and the excess resin liquid 3 cannot be squeezed out. Therefore, the heating temperature and heating time of the heat shrinkable tube 5 are set according to the shrinkage speed of the heat shrinkable tube 5, the curing conditions of the resin liquid 3, etc., and as an example, it is set to 100°C and 1 hour.

[0065] Note that, for the same reason, the heat shrinkable tube 5 in which the carbon fiber bundle 2 is inserted is not immersed in the resin liquid 3. This is because if the tube 5 is cured by the resin liquid 3, shrinkage is inhibited.

[0066] When a tube of a type that expands its opening by its own tension is used as the shrinkable tube 5, the carbon fiber bundle 2 can be shrunk by releasing the tension after the carbon fiber bundle 2 is inserted.

[0067] [Process for producing thermally conductive molded body]

[0068] Next, each manufacturing process of the thermally conductive molded body is described. As described above, the manufacturing method of the thermally conductive molded body using the present technology includes: a process of preparing a carbon fiber bundle 2 filled with a resin liquid; a tube shrinking process of inserting the carbon fiber bundle 2 filled with a resin liquid 3 into a shrinkable tube 5 and shrinking the tube 5; and a curing process of curing the resin liquid 3 filled between the carbon fibers.

[0069] like Figure 3 As shown in (A) to (C) of FIG. 1 , a carbon fiber bundle filled with a resin liquid can be formed by preparing a carbon fiber bundle 2 in which a plurality of carbon fibers 1 are oriented in the same direction and bundled, and filling the spaces between the carbon fibers of the carbon fiber bundle 2 with a resin liquid 3 .

[0070] The carbon fiber bundle forming step is a step of forming a bundle of carbon fibers 1. For example, it can be formed by twisting a plurality of carbon fibers to form elongated filamentary carbon fiber yarns, appropriately twisting a plurality of carbon fiber yarns to form long and strong carbon fiber yarns, and then bundling such carbon fiber yarns.

[0071] The resin liquid filling step is a step of filling the resin liquid 3 between the carbon fibers constituting the carbon fiber bundle 2, for example, Figure 3 As shown in FIG. 1 , the carbon fiber bundle 2 can be immersed in a container containing the resin liquid 3 so that the carbon fiber bundle 2 is impregnated with the resin liquid 3. Figure 3As shown in (B), the carbon fiber bundle 2 is immersed in the resin solution 3 from one end side in the orientation direction of the fibers, so that mixing of bubbles can be prevented and the air in the carbon fiber bundle 2 can be discharged from the other end side in the orientation direction of the fibers.

[0072] In addition, if Figure 4 As shown in (A) and (B) of , a carbon fiber bundle filled with resin liquid can be formed by a process of immersing carbon fiber 1 in resin liquid 3 and a process of forming carbon fiber bundle 2 in which carbon fiber 1 immersed in resin liquid 3 is oriented in the same direction and bundled. For the impregnation process of impregnating carbon fiber 1 into resin liquid 3, a plurality of carbon fibers can be twisted to form elongated filamentary carbon fiber filaments, and after appropriately twisting a plurality of carbon fiber filaments to form long and tough carbon fiber filaments, such carbon fiber filaments can be sequentially conveyed into a container filled with resin liquid 3 for continuous impregnation. For the formation process of carbon fiber bundle 2, it can be formed by orienting carbon fiber filaments coated with resin liquid 3 in the same direction and bundling them.

[0073] In addition, the filling of the resin liquid 3 between the carbon fibers can be performed by continuously and sequentially conveying a long aggregate of a plurality of carbon fiber bundles into a container containing the resin liquid 3, thereby continuously impregnating. Alternatively, the filling of the resin liquid 3 between the carbon fibers can be performed by spreading the resin liquid 3 on the carbon fiber filaments or the carbon fiber bundles 2, etc.

[0074] like Figure 5 As shown, the tube shrinking step is a step of inserting the carbon fiber bundle 2 filled with the resin liquid 3 from the opening of the shrinkable tube 5 to shrink the tube 5. As described above, when a heat-shrinkable tube 5 is used, a heating treatment is performed, and when a tube 5 that shrinks by tension is used, the tension is released to shrink it. In this way, the carbon fiber bundle 2 can be compressed, and the excess resin liquid 3 can be squeezed out from between the carbon fibers, so that the carbon fibers can be filled with high density.

[0075] In addition, in the resin liquid filling process, if the carbon fiber bundle 2 is only immersed in a container filled with resin liquid 3, sometimes the spaces between the carbon fibers are not fully filled with the resin liquid 3. However, through the tube shrinkage process, the resin liquid 3 filled between the carbon fibers fully reaches every corner of the carbon fiber bundle 2, and the resin liquid 3 can be reliably filled between the carbon fibers.

[0076] Then, the resin liquid 3 filled between the carbon fibers is cured by the curing step, thereby obtaining the thermally conductive molded body 10. As described above, when the heat-shrinkable tube 5 is used, the tube shrinking step and the curing step are performed simultaneously by performing the heating treatment, and the heating temperature and the heating time are set according to the shrinking speed of the heat-shrinkable tube 5, the curing conditions of the resin liquid 3, etc., so that the heat-shrinkable tube 5 shrinks before the resin liquid 3 filled between the carbon fibers is cured. When the tube 5 of the type that expands and contracts by the tension of the tube 5 itself is used, after the carbon fiber bundle 2 is inserted, the tension is released to perform the tube shrinking step, and then the resin liquid 3 is cured to obtain the thermally conductive molded body 10.

[0077] The heat conductive molded body 10 is formed by cutting the tube 5 with a cutter or the like to remove the tube 5. Figure 6 As shown, the thermally conductive molded body 10 is sliced ​​into sheets in a direction intersecting the orientation direction of the carbon fibers before or after the tube 5 is removed, thereby forming a thermally conductive sheet 11 sandwiched between a heat source and a heat dissipation member such as a semiconductor device.

[0078] It should be noted that the carbon fibers 1 contained in the thermally conductive sheet 11 are oriented in the thickness direction of the sheet. In addition, the thermally conductive sheet 11 is sliced ​​into sheets by the thermally conductive molded body 10, and the integrity achieved by twisting the carbon fibers and carbon fiber filaments is eliminated, but the integrity as a sheet is ensured by filling the resin liquid 3 between the carbon fibers and carbon fiber filaments and solidifying them.

[0079] The thickness of the thermally conductive sheet 11 is not particularly limited and can be appropriately changed according to the location where the sheet is used, and can be in the range of 0.2 mm to 5 mm when the sheet's adhesion and strength are taken into consideration. It should be noted that in addition to the thermally conductive sheet 11, the thermally conductive molded body 10 can also be used for other purposes by adjusting the thickness and shape of the slices.

[0080] According to the above process, by shrinking the shrinkable tube 5, the excess resin liquid 3 in the resin liquid 3 filled between the carbon fibers can be squeezed out. Then, after squeezing out the excess resin liquid 3, by solidifying the resin liquid 3 in the solidification process, the sheet shape is maintained by the resin liquid 3 filled and solidified between the carbon fibers, and the excess resin liquid 3 is removed, so that the thermal conductive sheet 11 in which the carbon fibers 1 are densely filled can be manufactured.

[0081] [Semiconductor devices]

[0082] Here, a description will be given of an example of use of the heat conductive sheet 11. The heat conductive sheet 11 is mounted on a semiconductor device built into various electronic devices and is sandwiched between a heat source and a heat dissipation member. Figure 2 An example of a semiconductor device is shown. Figure 2The semiconductor device 50 shown has at least an electronic component 51, a heat spreader 52, and a heat conductive sheet 11 sandwiched between the heat spreader 52 and the electronic component 51. The semiconductor device 50 has high heat dissipation performance by using the heat conductive sheet 11 densely filled with carbon fibers having excellent thermal conductivity.

[0083] There is no particular limitation on the electronic component 51, and it can be appropriately selected according to the purpose, for example, a CPU, an MPU, a graphic computing element, an image sensor, etc. There is no particular limitation on the heat spreader 52 as long as it is a component for dissipating the heat generated by the electronic component 51, and it can be appropriately selected according to the purpose. The thermal conductive sheet 11 is clamped between the thermal spreader 52 and the electronic component 51. In addition, the thermal conductive sheet 11 is clamped between the thermal spreader 52 and the heat sink 53, thereby constituting a heat dissipation component for dissipating the heat of the electronic component 51 together with the thermal spreader 52.

[0084] The installation location of the heat conducting sheet 11 is not limited to between the heat spreader 52 and the electronic component 51, or between the heat spreader 52 and the heat sink 53, and can be appropriately selected according to the configuration of the electronic device or semiconductor device. In addition, as a heat dissipation component, in addition to the heat spreader 52 and the heat sink 53, any component that conducts heat generated from a heat source and dissipates it to the outside can be used, for example, a heat sink, a cooler, a die pad, a printed circuit board, a cooling fan, a Peltier element, a heat pipe, a metal cover, an electronic device housing, etc.

[0085] [Modification 1]

[0086] like Figure 7 As shown, the tube 5 may be provided with a plurality of holes 6 on the side. The holes 6 are sized to be not filled when the tube 5 is shrunk. By providing the holes 6, when the tube 5 is shrunk, the excess resin liquid 3 can be discharged from the holes 6. The holes 6 are formed at least near the center of the tube 5 in the longitudinal direction, and are preferably formed throughout the entire tube 5.

[0087] In a case where the cylindrical tube 5 is provided with only openings for inserting the carbon fiber bundle 2 at both ends in the long dimension direction, when pressure is applied to the entire carbon fiber bundle 2 due to contraction, the remaining portion of the resin liquid 3 filled in the ends of the carbon fiber bundle 2 in the long dimension direction is discharged from the openings, but the resin liquid 3 filled near the center of the carbon fiber bundle 2 takes time to be discharged, and there is a possibility that the discharge may be insufficient.

[0088] Therefore, by providing a plurality of holes 6 on the side surface of the tube 5, the excess resin liquid 3 can be efficiently discharged, and the remaining portion near the center can be prevented from being solidified while remaining without being discharged.

[0089] In addition, if Figure 8 As shown, a mesh member 9 may be interposed between the tube 5 and the carbon fiber bundle. In this way, the remaining portion of the resin liquid 3 can also be discharged from the carbon fiber bundle 2. The mesh member 9 may be pre-set on the inner wall of the tube 5, or may be wound around the outer periphery of the carbon fiber bundle 2 and then inserted into the tube 5.

[0090] From the viewpoint of reliably discharging the excess of the resin liquid 3 , the mesh member 9 is preferably used together with the tube 5 having the holes 6 formed in the side surface as described above.

[0091] [Modification 2]

[0092] in addition, Figure 5 The tube 5 shown has a length greater than the entire length of the carbon fiber bundle 2, and the carbon fiber bundle 2 is inserted throughout its entire length, but it may also be Fig. 9 As shown, the tube 5 has a shorter length than the carbon fiber bundle 2. For the carbon fiber bundle 2, a portion of the length direction of the carbon fiber bundle 2 is inserted into the tube 5, so that it is inserted into a plurality of tubes 5 that are relatively shorter than the carbon fiber bundle 2. Fig. 9 In the structure shown, the carbon fiber bundle 2 can be compressed by contracting the tubes 5 , and the excess resin liquid 3 can be squeezed out from between the tubes 5 .

[0093] [Example]

[0094] Next, examples of the present technology will be described.

[0095] [Example 1]

[0096] In Example 1, XN100 (manufactured by Nippon Graphite Fiber Corporation) was used as the long-fiber carbon fiber to form a carbon fiber bundle. The thermal conductivity of the carbon fiber is 900 W / mK, and the carbon fiber density is 2.22 g / cm 3 . The ends of the carbon fiber bundle are bound and immersed in a container containing a two-component addition reaction type silicone resin (resin liquid), and the silicone resin is filled between the carbon fibers. Then, the carbon fiber bundle filled with silicone resin is placed in a heat shrinkable tube with an inner diameter of 50.8mm and a length of 200mm and left to stand in an oven. The heating conditions are set to 100°C and 1 hour. The size of the heat shrinkable tube after curing is an inner diameter of 40mm. A portion of the remaining silicon seeps out from the end of the heat shrinkable tube and solidifies.

[0097] The obtained thermally conductive molded body was cut into a quadrangular prism shape and then sliced ​​into 2.0 mm thick slices to obtain a thermally conductive sheet. When the cross section of the thermally conductive sheet was observed, it was confirmed that the carbon fibers were dense and had good thermal properties.

[0098] [Comparative Example 1]

[0099] In Comparative Example 1, XN100 (manufactured by Nippon Graphite Fiber Corporation) was used as the long-fiber carbon fiber to form a carbon fiber bundle. The thermal conductivity of the carbon fiber is 900 W / mK, and the carbon fiber density is 2.22 g / cm 3 The ends of the carbon fiber bundle were tied and immersed in a container containing a two-component addition reaction type silicone resin (resin liquid) to fill the silicone resin between the carbon fibers. Then, the carbon fiber bundle filled with silicone resin was placed in an oven. The heating conditions were set to 100°C for 1 hour.

[0100] The obtained thermally conductive molded body was cut into a quadrangular prism shape and then sliced ​​into 2.0 mm thick slices to obtain a thermally conductive sheet. When the cross section of the thermally conductive sheet was observed, there were areas where the carbon fibers were sparse and areas where they were dense, and therefore good thermal properties could not be obtained.

[0101] In summary, in Example 1, by placing the carbon fiber bundle filled with silicone resin in a shrinkable tube and applying pressure to squeeze out excess resin liquid, a thermally conductive sheet with high density of carbon fiber filling and excellent thermal conductivity is obtained.

[0102] On the other hand, in Comparative Example 1, since the carbon fiber bundle filled with silicone resin was directly cured, there were portions where the carbon fibers were dense and portions where they were sparse in the thermal conductive sheet, and the thermal resistance increased.

Claims

1. A method for producing a thermally conductive molded body, wherein: include: A step of preparing a carbon fiber bundle filled with a resin liquid; A step of inserting the carbon fiber bundle filled with the resin liquid into a shrinkable tube and then shrinking the tube; as well as a step of solidifying the resin liquid filled between the carbon fibers, Here, tension is applied to the opening of the shrinkable tube to expand the opening to be larger than the outer diameter of the carbon fiber bundle filled with the resin liquid, and after the carbon fiber bundle is inserted, the tension is released to shrink the tube.

2. A method for producing a thermally conductive molded body, wherein: include: A step of preparing a carbon fiber bundle filled with a resin liquid; A step of inserting the carbon fiber bundle filled with the resin liquid into a shrinkable tube and then shrinking the tube; as well as a step of solidifying the resin liquid filled between the carbon fibers, The tube is provided with a plurality of holes on the side.

3. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: The carbon fiber bundle filled with the resin liquid is formed by the step of preparing a carbon fiber bundle in which carbon fibers are oriented in the same direction and the step of filling the spaces between the carbon fibers of the carbon fiber bundle with the resin liquid.

4. The method for producing a thermally conductive molded body according to claim 3, wherein: The carbon fiber bundle is immersed in a resin liquid and pulled up from the resin liquid, so that the resin liquid is filled between the carbon fibers.

5. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: The carbon fiber bundle filled with the resin liquid is formed by the step of immersing the carbon fibers in the resin liquid and the step of forming a carbon fiber bundle in which the carbon fibers immersed in the resin liquid are oriented in the same direction and bundled.

6. The method for producing a thermally conductive molded body according to claim 2, wherein: The tube is formed of a heat shrink material, The tube is shrunk by heating it.

7. The method for producing a thermally conductive molded body according to claim 2, wherein: Tension is applied to the opening of the shrinkable tube to expand the opening to be larger than the outer diameter of the carbon fiber bundle filled with the resin liquid, and after the carbon fiber bundle is inserted, the tension is released to shrink the tube.

8. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: include: A cutting step of cutting the thermally conductive molded body in a direction intersecting with the orientation direction of the carbon fibers after the resin liquid is cured.

9. The method for producing a thermally conductive molded body according to claim 8, wherein: In the cutting step, the thermally conductive molded body is cut into sheets.

10. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: include: A step of removing the tube after the resin liquid is cured.

11. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: A mesh member is sandwiched between the tube and the carbon fiber bundle.

12. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: The tube has a length greater than the entire length of the carbon fiber bundle, The carbon fiber bundle is inserted into the tube over the entire length of the carbon fiber bundle.

13. The method for producing a thermally conductive molded body according to claim 1 or 2, wherein: The tube has a length shorter than that of the carbon fiber bundle, Regarding the carbon fiber bundle, a portion of the carbon fiber bundle in the longitudinal direction is inserted into the tube.

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