Heat dissipation sheet and method for manufacturing the same

Abstract

The present invention provides a heat-dissipating sheet that has excellent heat dissipation properties and is compact, particularly in the thickness direction, and a method for manufacturing the heat-dissipating sheet. The heat-dissipating sheet 1 of the present invention comprises a substrate 4, a heat-dissipating section 2 that is provided on one side of the substrate 4 and has straight fibers 21 that stand along the thickness direction of the substrate 4, and a fiber fixing layer 3 that is provided on one side of the substrate 4 and supports and fixes the straight fibers 21 with their base ends embedded therein, and the heat-dissipating section 2 has, in a plan view of the substrate 4, a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present.

Description

[Technical Field]

[0001] The present invention relates to a heat-dissipating sheet and a method for manufacturing the heat-dissipating sheet. [Background technology]

[0002] 2. Description of the Related Art Personal computers equipped with semiconductor devices, electronic components such as various sensors, generate a large amount of heat, and so in the past, heat dissipation sheets have been provided for the semiconductor devices in order to dissipate this generated heat.

[0003] This heat dissipation sheet is typically made primarily of a metal material such as aluminum, aluminum alloy, or copper, and has a structure with multiple rectangular fins standing upright from a rectangular base, giving it a comb-like cross-sectional shape (see, for example, Patent Document 1).

[0004] However, in order to achieve excellent heat dissipation efficiency in a heat dissipation sheet made primarily of such metal material, it is necessary to space long fins in the thickness direction (vertical direction) at a predetermined interval and erect them from the bottom, which poses the problem of increasing the sheet's size, particularly in the thickness direction.

[0005] In recent years, there has been a demand for miniaturization of semiconductor devices, and as a result, the heat dissipation sheets used in semiconductor devices also need to be miniaturized. However, as mentioned above, heat dissipation sheets primarily made of metal are not suitable for this miniaturization. As a result, it is sometimes impossible to secure space for the heat dissipation sheet, and even if space is secured, new space must be created to secure it, which results in a poor overall appearance of the electronic component equipped with the semiconductor device on which the heat dissipation sheet is formed. Furthermore, if the heat dissipation sheet is miniaturized, its heat dissipation performance becomes insufficient. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-71643 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a heat dissipation sheet that has excellent heat dissipation properties and is compact, particularly in the thickness direction, and a method for manufacturing the heat dissipation sheet. [Means for solving the problem]

[0008] Such objectives are as follows: (1) 9 This is achieved by the present invention described in (1) a substrate; a heat dissipation portion provided on one surface of the base material, having heat dissipation properties, and having straight fibers standing along the thickness direction of the base material; a fiber fixing layer provided on one surface of the base material, which supports and fixes the base ends of the straight fibers in an embedded state; The heat dissipation portion has, in a plan view of the base material, a first region in which the straight fibers are present and a second region in which the straight fibers are not present. death, In a plan view of the base material, the fiber fixing layer is present in a region overlapping with the second region. A heat dissipation sheet characterized by:

[0011] ( 2 The second region has an elongated shape in a plan view of the base material. To the above (1) The heat dissipation sheet described above.

[0012] ( 3 The width W of the second region is 200 μm or more and 1000 μm or less. (1) above The heat dissipation sheet according to claim 1.

[0013] ( 4 The ratio T / W of the thickness T of the heat dissipation portion to the width W of the second region is 0.4 or more and 5.0 or less. (3) above The heat dissipation sheet according to claim 1.

[0014] ( 5 The density of the straight fibers in the first region is 10,000 fibers / cm 2 Over 1 million strands / cm 2 is (1) to (3) above 10. The heat dissipation sheet according to any one of the preceding items. (6) The fiber fixing layer contains a photocurable resin. (1) to (3) above 10. The heat dissipation sheet according to any one of the preceding items.

[0015] ( 7 a first step of preparing a laminate having a substrate and a fiber fixing layer before curing provided on one surface side of the substrate; a second step of embedding straight fibers in the fiber fixing layer by electrostatic force so as to stand upright along the thickness direction of the base material to form a heat dissipation portion; a third step of curing the fiber fixing layer before curing; and a fourth step of removing a portion of the fiber fixing layer so as to form a first region in which the straight fibers are present and a second region in which the straight fibers are not present in the heat dissipation section when viewed in a plane of the substrate.

[0016] ( 8 a first step of preparing a laminate having a substrate and a fiber fixing layer before curing provided on one surface side of the substrate; a second step of embedding straight fibers in the fiber fixing layer by electrostatic force so as to stand upright along the thickness direction of the base material to form a heat dissipation portion; a third step of curing the fiber fixing layer before curing, The method for manufacturing a heat dissipation sheet is characterized in that in the second step, a first region in which the straight fibers are present and a second region in which the straight fibers are not present are formed in the heat dissipation section when viewed in a plane of the substrate. (9) preparing a laminate including a substrate and a fiber fixing layer before hardening that is provided on one surface of the substrate and has adhesiveness; a step of deactivating the tackiness of a portion of the fiber fixing layer before hardening; a step of embedding straight fibers in an uncured portion of the fiber fixing layer by electrostatic force so as to stand upright along the thickness direction of the base material to form a heat dissipation portion; and curing the fiber fixing layer before curing, A method for manufacturing a heat dissipation sheet, characterized in that in the process of forming the heat dissipation section, the straight fibers are embedded only in the portion of the fiber fixing layer before hardening, so that a first region in which the straight fibers are present is formed in the heat dissipation section, and the straight fibers are not embedded in the portion of the fiber fixing layer where the adhesiveness has been deactivated, so that a second region in which the straight fibers are not present is formed in the heat dissipation section. [Effects of the Invention]

[0017] According to the present invention, a heat dissipation sheet can be made that has excellent heat dissipation properties and is compact, particularly in the thickness direction (thinning). Therefore, when provided to a miniaturized semiconductor device, space for arranging the heat dissipation sheet can be easily secured, improving the overall appearance of the electronic component including the semiconductor device provided with the heat dissipation sheet and further reducing its weight. In particular, the heat dissipation section has a second region where no straight fibers are present, thereby improving the breathability of this region. This further enhances the heat dissipation properties of the heat dissipation section. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view showing a first embodiment of the heat dissipation sheet of the present invention. [Figure 2] FIG. 2 is a side view illustrating a method for manufacturing the heat dissipation sheet shown in FIG. [Figure 3] FIG. 3 is a side view showing a second embodiment of the heat dissipation sheet of the present invention. [Figure 4] FIG. 4 is a side view illustrating a method for manufacturing the heat dissipation sheet shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description of the heat-dissipating sheet and the method for manufacturing the heat-dissipating sheet of the present invention will now be given based on preferred embodiments shown in the accompanying drawings.

[0020] First Embodiment Figure 1 is a side view showing a first embodiment of the heat dissipation sheet of the present invention. In the following description, the upper side in Figure 1 will be referred to as "top" and the lower side as "bottom." The drawings used (including Figure 1 and the figures shown below) are enlarged or reduced as appropriate so that the parts being described can be recognized.

[0021] <Heat dissipation sheet 1> In this embodiment, the heat dissipation sheet 1 has a substrate 4, a fiber fixing layer 3 provided on the upper surface (one surface) of the substrate 4, and a heat dissipation section 2 formed on the upper surface (the surface opposite the substrate 4) of the fiber fixing layer 3. In this heat dissipation sheet 1, the heat dissipation section 2 includes a plurality of thermally conductive straight fibers 21, and the straight fibers 21 are configured so that their base ends are embedded and fixed in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3, and their tip ends are erected in the heat dissipation section 2 on the opposite side to the fiber fixing layer 3.

[0022] By configuring the heat dissipation sheet 1 in this way, it is possible to achieve miniaturization, particularly miniaturization (thinning) in the thickness direction (vertical direction). Therefore, when the heat dissipation sheet 1 is provided to correspond to a miniaturized semiconductor device, it is easy to ensure space for arranging the heat dissipation sheet 1. Therefore, the overall appearance of the electronic component including the semiconductor device provided with the heat dissipation sheet 1 is improved, and furthermore, the weight can be reduced.

[0023] Each part constituting the heat dissipation sheet 1 will be described below. <<Base material>> The base material 4 has an overall flat plate-like shape, i.e., a planar shape when viewed from above. The fiber fixing layer 3 and the heat dissipation section 2 are arranged in this order from the base material 4 side, and support the fiber fixing layer 3 and the heat dissipation section 2.

[0024] Examples of the main material of the substrate 4 include resin materials such as polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polypropylene, polyamide, polyimide, polycarbonate, and polyarylate, and glass materials such as soda glass and quartz glass, and one or more of these may be used in combination.

[0025] In addition to the main material as described above, the substrate 4 may further contain a particulate thermally conductive material for the purpose of improving the thermal conductivity of the substrate 4. This thermally conductive material is not particularly limited, and examples thereof include carbon-based materials such as graphite, ceramic materials such as silica, alumina, and silicon nitride, and metal-based materials such as aluminum and copper, and one or more of these may be used in combination.

[0026] The thermal conductivity of base material 4 is not particularly limited, but is preferably about 0.2 W / m·K or more and 400 W / m·K or less, and more preferably about 12 W / m·K or more and 400 W / m·K or less. This allows heat generated in the semiconductor device on which heat dissipation sheet 1 is provided to be conducted (transmitted) to heat dissipation portion 2 via base material 4 with excellent thermal conductivity.

[0027] The average thickness of the substrate 4 is not particularly limited, but is preferably about 9 μm to 200 μm, and more preferably about 12 μm to 70 μm, which reliably supports the fiber fixing layer 3 and the heat dissipation portion 2 while reliably preventing the heat dissipation sheet 1 from becoming too large in the thickness direction (vertical direction).

[0028] <<Fiber fixing layer>> The fiber fixing layer 3 has an overall layered shape and a planar shape in plan view similar to that of the substrate 4, and has the function of fixing the straight fibers 21 on the upper surface side (one side) of the fiber fixing layer 3 by fixing the base ends of the straight fibers 21 in an embedded state along their thickness direction (vertical direction).

[0029] When the straight fibers 21 are fixed by the fiber fixing layer 3 by embedding the base ends of the straight fibers 21 in the fiber fixing layer 3 using an electrostatic flocking method described below, the fiber fixing layer 3 is preferably configured with an adhesive layer containing an adhesive as a main material. As a result, the straight fibers 21 can be reliably fixed by the fiber fixing layer 3 by solidifying or curing the adhesive layer after embedding the base ends of the straight fibers 21 in the fiber fixing layer 3 configured with the adhesive layer using the electrostatic flocking method.

[0030] Examples of such adhesives include silicone-based, urethane resin-based, epoxy-based, polyolefin-based, chlorinated polyolefin-based, acrylic-based, cyanoacrylate-based, rubber-based, polyester-based, polyimide-based, and phenol-based adhesives, adhesives containing various thermosetting resins, and adhesives containing various photocurable resins.

[0031] In addition to the adhesive as the main material as described above, the fiber fixing layer 3 may further contain a particulate heat-conducting material for the purpose of improving the thermal conductivity of the fiber fixing layer 3. As this heat-conducting material, the same materials as those listed for the substrate 4 can be used.

[0032] The thermal conductivity of this fiber fixing layer 3 is not particularly limited, but is preferably about 0.2 W / m·K or more and 400 W / m·K or less, and more preferably about 0.6 W / m·K or more and 24 W / m·K or less. This allows the heat generated in the semiconductor device on which the heat dissipation sheet 1 is provided to be conducted (transmitted) to the heat dissipation part 2 side via the fiber fixing layer 3 with excellent thermal conductivity.

[0033] The average thickness of the fiber fixing layer 3, i.e., the average thickness in the region where the straight fibers 21 are not embedded, is not particularly limited, but is preferably about 5 μm to 100 μm, and more preferably about 10 μm to 70 μm. This allows the fiber fixing layer 3 to reliably fix the straight fibers 21 in the heat dissipation section 2 in an upright state with their tips facing upward (the side opposite to the fiber fixing layer 3).

[0034] In addition, various additives such as plasticizers, tackifiers, thickeners, fillers, antioxidants, preservatives, anti-mold agents, dyes, pigments, etc. may be added to the above-mentioned base material 4 and fiber fixing layer 3, respectively, as needed.

[0035] <<Heat dissipation section>> The heat dissipation section 2 is provided on the substrate 4 via the fiber fixing layer 3, and when the heat dissipation sheet 1 is provided corresponding to the semiconductor device, the heat generated in the semiconductor device is transmitted through the substrate 4 and the fiber fixing layer 3, and then this heat dissipation section 2 has the function of dissipating the heat outside the semiconductor device and the heat dissipation sheet 1, i.e., to the outside air.

[0036] In the present invention, the heat dissipation section 2 includes a plurality of straight fibers 21 that are thermally conductive, i.e., have heat dissipation properties. The heat dissipation section 2 has a planar shape in a plan view and has thermal conductivity. As shown in Fig. 1, the straight fibers 21 are configured to stand in the thickness direction with their base ends embedded and fixed in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3, and their tip ends facing upward (opposite the fiber fixing layer 3).

[0037] By configuring the heat dissipation section 2 in this way, it is possible to reduce the size of the heat dissipation sheet 1, particularly in the thickness direction, while increasing the contact area between the heat dissipation section 2 (straight fibers 21) and the outside of the semiconductor device and heat dissipation sheet 1, i.e., the outside air. Therefore, heat generated in the semiconductor device can be dissipated via the heat dissipation sheet 1 with excellent heat dissipation efficiency.

[0038] The straight fibers 21 are not particularly limited, and examples thereof include short fibers such as glass fibers, carbon fibers, polyamide fibers (nylon 6 fibers, nylon 46 fibers, nylon 66 fibers, aramid fibers, etc.), modified polyphenylene ether (modified PPE) fibers, poly-p-phenylenebenzobisoxazole (PBO) fibers, polyvinyl alcohol (PVA) fibers, polyolefin fibers (polyethylene fibers, polypropylene fibers, etc.), plastic fibers such as polyimide fibers, inorganic fibers such as carbon fibers and basalt fibers, natural fibers such as cotton, hemp, and wool, and metal fibers such as stainless steel fibers, and one or more of these may be used in combination.

[0039] The straight fibers 21 preferably have a thermal conductivity of 0.2 W / m·K or more and 900 W / m·K or less, and more preferably 10 W / m·K or more and 700 W / m·K or less. The straight fibers 21 also preferably have a thermal emissivity of 0.7 or more, and more preferably 0.8 or more. By using straight fibers 21 whose thermal conductivity and thermal emissivity are within the above ranges, heat generated in the semiconductor device can be dissipated via the heat dissipation sheet 1 (straight fibers 21) with greater heat dissipation efficiency.

[0040] Furthermore, the conductivity of the straight fibers 21 is not particularly limited, but in applications where insulation is important, an electrical resistivity of 100 kΩ·m or more is preferable. This ensures that insulation is maintained in the heat dissipation section 2 when the heat dissipation sheet 1 is provided for a semiconductor device. Furthermore, the heat dissipation section 2 made of the straight fibers 21 can be reliably formed using the electrostatic flocking method described below.

[0041] Considering the thermal conductivity, thermal emissivity, and electrical conductivity of the straight fibers 21 as described above, the straight fibers 21 are preferably at least one of carbon fibers, aramid fibers, nylon 6 fibers, stainless steel fibers, and PBO fibers, etc., and PBO fibers, etc. are more preferably used when ensuring insulation.

[0042] In the heat dissipation portion 2, the length of the straight fibers 21 protruding from the fiber fixing layer 3 on the tip side thereof is preferably 70 μm or more and 7000 μm or less, and more preferably 150 μm or more and 5000 μm or less.

[0043] The straight fibers 21 preferably have a thickness of 0.9 μm or more and 20 μm or less, and more preferably 4 μm or more and 20 μm or less.

[0044] Furthermore, when the length of the straight fiber 21 protruding from the fiber fixing layer 3 is L [μm] and the thickness is t [μm], the aspect ratio L / t is preferably 10 or more and 400 or less, and more preferably 20 or more and 100 or less.

[0045] By setting the length L, thickness T, and aspect ratio L / t of the straight fibers 21 within the above ranges, it is possible to reliably achieve a reduction in the thickness of the heat dissipation section 2 and therefore the heat dissipation sheet 1, while dissipating the heat generated in the semiconductor device through the heat dissipation sheet 1 with better heat dissipation efficiency.

[0046] Here, the heat dissipation part 2 has, in a plan view of the base material 4, a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present. In this specification, "the straight fibers 21 are not present" means that the density of the straight fibers 21 (average density in the entire area of ​​the second region 2B) is 1000 fibers / cm 2 It says that the following is true.

[0047] The first regions 2A and the second regions 2B are alternately arranged in the horizontal direction in FIG. 1. Each of the first regions 2A has the same width, and each of the second regions 2B has the same width. However, each of the first regions 2A may have a different width. Also, each of the second regions 2B may have a different width.

[0048] The first region 2A and the second region 2B are elongated and extend from the front to the depth of the page in FIG. 1. That is, the second region 2B is elongated when the base material 4 is viewed in a plan view. Therefore, the second region 2B can be said to be a groove extending from the front to the depth of the page in FIG. 1. This configuration can improve the breathability of the second region 2B. That is, it is possible to create an air flow in the second region 2B. As a result, the heat of the straight fibers 21 in the first region 2A is efficiently dissipated by the air flowing in the second region 2B. This can further improve the heat dissipation properties of the heat dissipation sheet 1 as a whole.

[0049] The density of the straight fibers 21 in the first region 2A is 10,000 fibers / cm 2 Over 1 million strands / cm 2 It is preferable that the density is 20,000 fibers / cm or less. 2 Over 500,000 strands / cm 2 It is more preferable that the density is equal to or less than this. This allows the heat dissipation properties in the first region 2A to be sufficiently improved. In particular, in the present invention, the second region 2B is formed, and the total number of straight fibers 21 tends to be smaller compared to a heat dissipation sheet whose entire area is the first region 2A. Therefore, by providing the straight fibers 21 at the above-mentioned density, the heat dissipation properties in the first region 2A can be improved and a decrease in the heat dissipation properties of the heat dissipation sheet 1 as a whole can be prevented.

[0050] The width W (average width) of the second region 2B is preferably 200 μm or more and 1000 μm or less, and more preferably 300 μm or more and 800 μm or less, which can more reliably improve the breathability of the second region 2B.

[0051] The ratio T / W of the thickness T (average thickness) [μm] of the heat dissipation portion 2 to the width W (average width) [μm] of the second region is preferably 0.4 or more and 5.0 or less, and more preferably 0.8 or more and 3.0 or less. This more reliably improves the breathability of the second region 2B and sufficiently improves the heat dissipation properties of the first region 2A. This further improves the heat dissipation properties of the heat dissipation sheet 1.

[0052] In addition, the area occupied by the first regions 2A in the total area of ​​the heat dissipation sheet 1 in a plan view (the sum of the areas of the first regions 2A) is defined as S1 [cm 2 ], and the area occupied by the second regions 2B in the total area of ​​the heat dissipation sheet 1 in a plan view (the sum of the areas of the second regions 2B) is S2 [cm 2 When S2 / S1 is 0.1 or more and 0.9 or less, and more preferably 0.2 or more and 0.8 or less, S2 / S1 is preferably 0.1 or more and 0.9 or less, and more preferably 0.2 or more and 0.8 or less. This makes it possible to more reliably improve the heat dissipation properties of the heat dissipation sheet 1.

[0053] It is particularly preferable that S2 / S1 is 0.2 or more and 0.8 or less, and the ratio T / W is 0.8 or more and 3.0 or less, which can more reliably improve the heat dissipation properties of the heat dissipation sheet 1.

[0054] In this embodiment, the fiber fixing layer 3 is not present in the region overlapping with the second region 2B in a plan view of the base material 4. That is, the fiber fixing layer 3 is patterned to correspond to the first region 2A and the second region 2B. This allows the second region 2B to be deeper, thereby further improving breathability.

[0055] As described above, the heat dissipation sheet 1 includes a substrate 4, a heat dissipation section 2 provided on one side of the substrate 4, the heat dissipation section 2 having straight fibers 21 extending along the thickness direction of the substrate 4, and a fiber fixing layer 3 provided on one side of the substrate 4 for supporting and fixing the base ends of the straight fibers 21 embedded therein. The heat dissipation section 2 has, in a plan view of the substrate 4, a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present. This allows the heat dissipation sheet 1 to have excellent heat dissipation properties and be compact, particularly in the thickness direction (thinning). Therefore, when the heat dissipation sheet 1 is provided to a miniaturized semiconductor device, space for the heat dissipation sheet can be easily secured, improving the overall appearance of an electronic component including a semiconductor device provided with the heat dissipation sheet 1 and further reducing its weight. In particular, since the heat dissipation part 2 has the second region 2B where the straight fibers 21 are not present, the breathability of this region can be improved. Therefore, the heat dissipation property of the heat dissipation part 2 can be further improved.

[0056] The locations, numbers and shapes of the first regions 2A and second regions 2B are not limited to the illustrated configuration.

[0057] It is preferable that such straight fibers 21 are implanted in the fiber fixing layer 3 using an electrostatic flocking method, that is, the straight fibers 21 are embedded by electrostatic force. The electrostatic flocking method makes it possible to relatively easily form straight fibers 21 having the above-described configuration. Therefore, the following describes, as an example, a method for manufacturing a heat dissipation sheet 1 having a heat dissipation portion 2, in which a heat dissipation portion 2 made of straight fibers 21 is formed using the electrostatic flocking method.

[0058] <Method of manufacturing the heat dissipation sheet 1> Fig. 2 is a side view for explaining a manufacturing method for manufacturing the heat dissipation sheet shown in Fig. 1. In the following description, the upper side in Fig. 2 will be referred to as "upper" and the lower side as "lower".

[0059] Before describing the method for manufacturing the heat-dissipating sheet 1, the heat-dissipating sheet manufacturing apparatus used in the method for manufacturing the heat-dissipating sheet 1 will be described below.

[0060] The heat-dissipating sheet manufacturing apparatus 100 shown in FIG. 2 includes an electrode plate 110, a counter electrode plate 120, and a DC voltage generator .

[0061] The electrode plate 110 is negatively charged by a DC voltage generator 130 serving as a voltage application means.

[0062] This electrode plate 110 has a holder 115 on the surface (underside) facing the counter electrode plate 120, and is configured so that the holder 115 can hold (place) the substrate 4 on which the fiber fixing layer 3 is formed, with the fiber fixing layer 3 facing the counter electrode plate 120.

[0063] The counter electrode plate 120 is positively charged by a DC voltage generator 130 serving as a voltage application means, and is disposed opposite the electrode plate 110 .

[0064] The counter electrode plate 120 is configured so that the straight fibers 21 for forming the heat dissipation portion 2 can be placed on the surface (upper surface) on the electrode plate 110 side. The positive and negative polarities of the electrode plate 110 and the counter electrode plate 120 may be reversed.

[0065] The DC voltage generator 130 is a voltage application means for applying a voltage to the electrode plate 110 and the counter electrode plate 120, and is electrically connected via wiring so that the electrode plate 110 side is the negative electrode and the counter electrode plate 120 side is the positive electrode.

[0066] The thermally conductive sheet 1 is manufactured by the thermally conductive sheet manufacturing method using the thermally conductive sheet manufacturing apparatus 100 as described above.

[0067] The method for manufacturing the heat dissipation sheet includes a first step of holding a substrate 4 having a fiber fixing layer 3 before solidification or hardening in a holder 115 and placing straight fibers 21 on a counter electrode plate 120; a second step of operating a DC voltage generator 130 to negatively charge the electrode plate 110 and positively charge the counter electrode plate 120, causing the straight fibers 21 to fly from the counter electrode plate 120 to the electrode plate 110, thereby implanting the straight fibers 21 into the fiber fixing layer 3; a third step of solidifying or curing the fiber fixing layer 3 with the implanted straight fibers 21, thereby fixing the straight fibers 21 to the fiber fixing layer 3; and a fourth step of removing a portion of the fiber fixing layer 3 so as to form a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present in the heat dissipation section 2 when viewed in a plane of the substrate 4.

[0068] Each step for manufacturing the heat dissipation sheet 1 will be described in detail below. [A] First, the substrate 4 having the fiber fixing layer 3 before solidification or hardening is held by a holder 115, and the straight fibers 21 are placed on the counter electrode plate 120 (first step).

[0069] In this first step, first, a laminate 5 is prepared, which includes a substrate 4 and a pre-solidified or pre-cured fiber fixing layer 3 (adhesive layer) provided on one surface of the substrate 4. Then, the laminate 5 is held by a holder 115 so that the fiber fixing layer 3 faces the counter electrode plate 120. In addition, the straight fibers 21 are placed on the counter electrode plate 120.

[0070] As a result, as shown in FIG. 2(a), the pre-solidified or pre-cured fiber fixing layer 3 and the straight fibers 21 are arranged opposite each other with a space between the electrode plate 110 and the counter electrode plate 120.

[0071] [B] Next, the DC voltage generator 130 is activated to negatively charge the electrode plate 110 and positively charge the counter electrode plate 120, causing the straight fibers 21 to fly from the counter electrode plate 120 to the electrode plate 110, thereby implanting the straight fibers 21 into the fiber fixing layer 3 (second step).

[0072] This second step is performed by operating DC voltage generator 130 to apply a voltage between electrode plate 110 and counter electrode plate 120, thereby negatively charging electrode plate 110 and positively charging counter electrode plate 120, thereby generating an electrostatic field between electrode plate 110 and counter electrode plate 120.

[0073] At this time, the straight fibers 21 placed on the counter electrode plate 120 are positively charged due to the counter electrode plate 120 being positively charged. Because the electrode plate 110 is negatively charged due to the positive charging of the straight fibers 21, the straight fibers 21 fly in the electrostatic field toward the electrode plate 110.

[0074] At this time, the straight fiber 21 flies in the space (electrostatic field) between the electrode plate 110 and the counter electrode plate 120 in the vertical direction with the base end facing the electrode plate 110 and the tip end facing the counter electrode plate 120.

[0075] The holder 115 on the electrode plate 110 side holds the substrate 4 with the pre-solidified or pre-cured fiber fixing layer 3, with the fiber fixing layer 3 facing the counter electrode plate 120. Therefore, as shown in FIG. 2(b), the straight fibers 21 flying from the counter electrode plate 120 side are fixed (implanted) to the surface of the fiber fixing layer 3 opposite the substrate 4, with part of their base ends piercing (embedding) into the fiber fixing layer 3.

[0076] The straight fibers 21 continue to fly from the opposing electrode plate 120 toward the electrode plate 110 until the planting density of the straight fibers 21 in the fiber fixing layer 3 reaches a predetermined density, and then the operation of the DC voltage generator 130 is stopped (see Figure 2(c)).

[0077] [C] Next, the fiber fixing layer 3 with the implanted straight fibers 21 is solidified or cured to fix the straight fibers 21 to the fiber fixing layer 3 (third step).

[0078] As a result, the fiber fixing layer 3 before solidification or hardening solidifies or hardens, so that the straight fibers 21 are fixed with their base ends embedded in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3. As a result, on the side of the fiber fixing layer 3 opposite the substrate 4, as shown in Fig. 2(c), a heat dissipation section 2 is formed in which the straight fibers 21 are arranged upright in the vertical direction with the tip ends of the straight fibers 21 facing downward (opposite the fiber fixing layer 3).

[0079] When the fiber fixing layer 3 is configured as an adhesive layer containing a solidifying or thermosetting adhesive, this third step is carried out by heating the fiber fixing layer 3. When the fiber fixing layer 3 is configured as an adhesive layer containing a light-setting adhesive, this third step is carried out by irradiating the fiber fixing layer 3 with light. By solidifying or curing the fiber fixing layer 3, the straight fibers 21 are fixed by the fiber fixing layer 3 with the base ends of the straight fibers 21 embedded in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3.

[0080] [D] Next, a portion of the solidified or hardened fiber fixing layer 3 is removed together with the straight fibers 21 to form the first region 2A and the second region 2B in the heat dissipation section 2. That is, the portion of the fiber fixing layer 3 corresponding to the second region 2B is removed together with the straight fibers 21 (fourth step). This results in the heat dissipation sheet 1 shown in FIG. 1.

[0081] The removal of the fiber fixing layer 3 in this fourth step may be chemical or physical. Examples of chemical removal include methods using a stripping agent or oxygen plasma. Through the steps described above, the heat dissipation sheet 1 is manufactured.

[0082] Thus, the method for manufacturing the heat dissipation sheet 1 includes the following steps: a first step of preparing a laminate 5 having a substrate 4 and an uncured fiber fixing layer 3 provided on one side of the substrate 4; a second step of forming the heat dissipation section 2 by embedding straight fibers 21 in the fiber fixing layer 3 using electrostatic force so that they stand along the thickness direction of the substrate 4; a third step of curing the uncured fiber fixing layer 3; and a fourth step of removing a portion of the fiber fixing layer 3 so as to form a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present in the heat dissipation section 2 in a plan view of the substrate 4. This makes it possible to easily and accurately manufacture a heat dissipation sheet 1 that has high heat dissipation properties while being compact, particularly in the thickness direction (thinner).

[0083] Second Embodiment Next, a second embodiment of the heat dissipation sheet of the present invention will be described.

[0084] Fig. 3 is a side view showing a second embodiment of the heat-dissipating sheet of the present invention, Fig. 4 is a side view for explaining a manufacturing method for manufacturing the heat-dissipating sheet shown in Fig. 3.

[0085] The following description of the heat dissipating sheet 1A of the second embodiment will focus on the differences from the heat dissipating sheet 1 of the first embodiment, and a description of similar points will be omitted.

[0086] <Heat dissipation sheet 1A> In the heat dissipation sheet 1A of this embodiment, the fiber fixing layer 3 is present in the region overlapping with the second region 2B in a plan view of the substrate 4. That is, the second region 2B is configured so that only the straight fibers 21 are absent. With this configuration, the thickness of the fiber fixing layer 3 can be made uniform in the surface direction of the heat dissipation sheet 1. Therefore, in addition to the effects described above, excellent durability can be exhibited.

[0087] <Method of manufacturing the heat dissipation sheet 1A> Each step for producing the heat dissipation sheet 1A will be described in detail below. [A] First, as shown in Figure 4(a), a substrate 4 having a fiber fixing layer 3 before solidification or hardening is held in a holder 115, and straight fibers 21 are placed on a counter electrode plate 120 (first step).

[0088] In this first step, first, a laminate 5 is prepared, which includes a substrate 4 and a pre-solidified or pre-cured fiber fixing layer 3 (adhesive layer) provided on one surface of the substrate 4. Then, the adhesiveness of a portion 31 of the fiber fixing layer 3 corresponding to the second region 2B is deactivated.

[0089] In this embodiment, the fiber fixing layer 3 preferably contains a photocurable resin, which makes it possible to deactivate (cure) the adhesiveness of the portion 31 corresponding to the second region 2B by a simple method of exposing the portion 31 to light and irradiating the other portion with light using a mask that covers the other portion.

[0090] Such a laminate 5 is held by a holder 115 so that the fiber fixing layer 3 faces the counter electrode plate 120. In addition, the straight fibers 21 are placed on the counter electrode plate 120, and the second and third steps are carried out in the same manner as in the first embodiment.

[0091] 4(b) and 4(c), in the second step, the straight fibers 21 flying from the counter electrode plate 120 side are implanted with their base ends piercing only the unhardened portion 31. That is, a first region 2A is formed in the portion 31, and the straight fibers 21 do not pierce the other regions, forming second regions 2B.

[0092] Then, the heat dissipation sheet 1A can be obtained by carrying out the third step in the same manner as in the first embodiment. In this manner, in this embodiment, the first region 2A and the second region 2B are formed in the second step.

[0093] The second and third steps may be performed without deactivating the adhesiveness of the portion 31. In this case, in the second step, the fibers are implanted in a state in which a mask that covers the portion of the fiber fixing layer 3 corresponding to the second region 2B and has an opening in the portion corresponding to the first region 2A is placed on the counter electrode plate 120 side of the fiber fixing layer 3. In either case, the first region 2A and the second region 2B can be formed in the second step.

[0094] Thus, the method for manufacturing the heat dissipation sheet 1A includes a first step of preparing a laminate 5 having a substrate 4 and an uncured fiber fixing layer 3 provided on one side of the substrate 4, a second step of forming a heat dissipation section 2 by embedding straight fibers 21 in the fiber fixing layer 3 using electrostatic force so that they stand along the thickness direction of the substrate 4, and a third step of curing the uncured fiber fixing layer 3. In the second step, in a plan view of the substrate 4, a first region 2A where the straight fibers 21 are present and a second region 2B where the straight fibers 21 are not present are formed in the heat dissipation section 2. This makes it possible to easily and accurately manufacture a heat dissipation sheet 1 that has high heat dissipation properties while being compact, particularly in the thickness direction (thinner thickness).

[0095] Although the heat-dissipating sheet and the method for manufacturing the heat-dissipating sheet of the present invention have been described above, the present invention is not limited to this.

[0096] For example, in the heat dissipation sheet of the present invention, each component can be replaced with any component that can exert a similar function, or any component can be added.

[0097] Furthermore, in the method for producing a heat-dissipating sheet of the present invention, each step can be replaced with any step that can exert a similar function, or any step can be added. [Industrial Applicability]

[0098] According to the present invention, it is possible to provide a heat dissipation sheet that has excellent heat dissipation properties and is compact, particularly in the thickness direction. Therefore, the present invention has industrial applicability. [Explanation of symbols]

[0099] 1 Heat dissipation sheet 1A Heat Dissipation Sheet 2 Heat dissipation part 2A 1st area 2B 2nd area 21 Straight fibers 3. Fiber fixing layer 31 parts 4 Base material 5. Laminate 100 Heat dissipation sheet manufacturing equipment 110 Electrode plate 115 Holder 120 Counter electrode plate 130 DC voltage generator T Thickness

Claims

1. Substrate and A heat dissipation section is provided on one side of the substrate, has heat dissipation properties, and has straight fibers that are erected along the thickness direction of the substrate, The substrate comprises a fiber fixing layer provided on one side of the substrate, which supports and fixes the base end of the straight fiber in an embedded state, The heat dissipation portion has, in a plan view of the substrate, a first region in which the straight fibers are present and a second region in which the straight fibers are not present. A heat dissipation sheet characterized in that, in a plan view of the substrate, the fiber fixing layer is present in the region that overlaps with the second region.

2. The heat dissipation sheet according to claim 1, wherein the second region has an elongated shape in a plan view of the substrate.

3. The heat dissipation sheet according to claim 1, wherein the width W of the second region is 200 μm or more and 1000 μm or less.

4. The heat dissipation sheet according to claim 3, wherein the ratio T / W of the thickness T of the heat dissipation portion to the width W of the second region is 0.4 or more and 5.0 or less.

5. The density of straight fibers in the first region is 10,000 fibers / cm². ２ Over 1 million units / cm ２ The heat dissipation sheet according to any one of claims 1 to 3 below.

6. The heat dissipation sheet according to any one of claims 1 to 3, wherein the fiber fixing layer comprises a photocurable resin.

7. A first step is to prepare a laminate having a base material and a fiber fixing layer provided on one side of the base material before curing, A second step involves embedding straight fibers in the fiber fixing layer by electrostatic force so that they are erected along the thickness direction of the substrate to form a heat dissipation section. A third step of curing the fiber fixing layer before hardening, A method for manufacturing a heat dissipation sheet, comprising a fourth step of removing a portion of the fiber fixing layer so that, in a plan view of the substrate, a first region in which the straight fibers exist and a second region in which the straight fibers do not exist are formed in the heat dissipation portion.

8. A first step is to prepare a laminate having a base material and a fiber fixing layer provided on one side of the base material before curing, A second step involves embedding straight fibers in the fiber fixing layer by electrostatic force so that they are erected along the thickness direction of the substrate to form a heat dissipation section. The process includes a third step of curing the fiber fixing layer before hardening, A method for manufacturing a heat dissipation sheet, characterized in that, in the second step, a first region in which the straight fibers are present and a second region in which the straight fibers are not present are formed in the heat dissipation portion of the substrate in a plan view.

9. A step of preparing a laminate having a base material and a fiber fixing layer provided on one side of the base material and having adhesive properties before curing, A step of deactivating the tackiness of a portion of the fiber fixing layer before hardening, The process of forming a heat dissipation section in the portion of the fiber-fixed layer before hardening by embedding straight fibers in an upright position along the thickness direction of the substrate using electrostatic force, The process includes a step of curing the fiber fixing layer before hardening, A method for manufacturing a heat dissipation sheet, characterized in that, in the step of forming the heat dissipation portion, the straight fibers are embedded only in the portion of the fiber fixing layer before hardening, so that a first region where the straight fibers are present is formed in the heat dissipation portion, and the straight fibers are not embedded in the portion of the fiber fixing layer where the adhesiveness has been deactivated, so that a second region where the straight fibers are absent is formed in the heat dissipation portion.

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