Heat dissipation sheet

Abstract

The present invention provides a heat dissipation sheet that has excellent heat dissipation properties and is miniaturized, particularly in the thickness direction. The heat dissipation sheet 1 of the present invention comprises a fiber fixing layer 3 as an adhesive layer having adhesive properties, and a heat dissipation layer 2 provided on one side of the fiber fixing layer 3 and having straight fibers 21 having heat dissipation properties. The base ends of the straight fibers 21 are embedded in the fiber fixing layer 3 from one side and fixed to the fiber fixing layer 3, and the other side of the fiber fixing layer 3 is used to be attached to a semiconductor device, which is an example of an object.

Description

[Technical Field]

[0001] This invention relates to a heat dissipation sheet. [Background technology]

[0002] Personal computers equipped with semiconductor devices, as well as electronic components such as various sensors, generate a large amount of heat. Therefore, heat dissipation sheets have traditionally been provided for semiconductor devices to dissipate this heat.

[0003] As such, heat dissipation sheets are typically made primarily of metal materials such as aluminum, aluminum alloys, or copper, and have been proposed to have a structure in which multiple rectangular fins are erected from a rectangular base, resulting in a comb-like cross-sectional shape (see, for example, Patent Document 1).

[0004] However, in heat dissipation sheets made primarily of metal materials, achieving excellent heat dissipation efficiency requires long fins in the thickness direction (vertical direction) spaced apart at predetermined intervals and erected vertically on the bottom surface. This leads to the problem of increasing the size of the sheet, particularly in the thickness direction.

[0005] Furthermore, in recent years, there has been a demand for miniaturization of semiconductor devices, and consequently, the heat dissipation sheets provided on these devices also need to be miniaturized. However, as mentioned above, heat dissipation sheets made primarily of metal are not suitable for such miniaturization. As a result, it may be impossible to secure space for the heat dissipation sheet, or even if space can be secured, it may be necessary to create additional space to accommodate it, leading to a problem where the overall appearance of the electronic component equipped with the semiconductor device having the heat dissipation sheet deteriorates. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-71643 [Overview of the project] [Problems that the invention aims to solve]

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

[0008] These objectives are achieved by the present invention as described in (1) to (7) below. (1) An adhesive layer having adhesive properties, The adhesive layer comprises a heat dissipation layer provided on one side of the adhesive layer and having straight fibers that have heat dissipation properties, The straight fibers are fixed to the adhesive layer by embedding their base ends from one side of the adhesive layer. The other side of the adhesive layer is used to adhere to an object, When the thickness of the adhesive layer is T1, and the length of the portion of the straight fibers embedded in the adhesive layer is L1, then L1 / T1 is between 0.3 and 1. The aforementioned T1 is between 10 μm and 1000 μm. the law of nature, In a plan view, it has a first region where the straight fibers exist and a second region where the straight fibers do not exist. In a plan view, the adhesive layer is present in the first and second regions. A heat dissipation sheet characterized by the following features.

[0009] (2) The heat dissipation sheet according to (1) above, wherein the elastic modulus of the adhesive layer at room temperature is 0.1 MPa or more and 10 MPa or less.

[0010] (3) The heat dissipation sheet according to (1) or (2) above, wherein the elastic modulus of the adhesive layer at high temperatures is 0.01 MPa or more and 5 MPa or less.

[0011] (4) The heat dissipation sheet according to any one of (1) to (3) above, wherein the thermal conductivity of the adhesive layer is 0.2 W / m·K or more and 1 W / m·K or less.

[0012] (5) The heat dissipation sheet according to any one of (1) to (4) above, wherein the adhesive layer contains a thermosetting component. (6) The heat dissipation sheet according to any one of (1) to (4) above, wherein the adhesive layer contains a photocurable component.

[0014] ( 7 ) The heat dissipation sheet according to any one of (1) to ( 6 ) above, further comprising a release sheet provided on the other surface side of the adhesive layer.

Advantages of the Invention

[0015] According to the present invention, the heat dissipation sheet can be provided with excellent heat dissipation performance and can be miniaturized, particularly in the thickness direction (thinning). Therefore, when provided corresponding to a miniaturized semiconductor device, it is possible to easily secure a space for arranging this heat dissipation sheet, improve the overall appearance of the electronic component including the semiconductor device provided with the heat dissipation sheet, and further, it can be made lighter in weight.

Brief Description of the Drawings

[0016] [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 for explaining a manufacturing method of manufacturing the heat dissipation sheet shown in FIG. 1. [Figure 3] FIG. 3 is a side view showing a second embodiment of the heat dissipation sheet of the present invention.

Embodiments for Carrying Out the Invention

[0017] [[ID=​​​​​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 part of Figure 1 will be referred to as "top" and the lower part as "bottom". Also, the drawings used (including Figure 1 and the drawings shown below) have been enlarged or reduced as appropriate so that the parts being described are recognizable.

[0019] The following describes the various components that make up the heat dissipation sheet 1. <Heat dissipation sheet> <<Base material (release sheet)>> The base material 4 is a release sheet, and the fiber fixing layer 3 and the heat dissipation layer 2 are provided in that order from the base material 4 side, supporting the fiber fixing layer 3 and the heat dissipation layer 2 (see Figure 1(a)). When using the heat dissipation sheet 1, the fiber fixing layer 3 is peeled off from the base material 4 (see Figure 1(b)), and the fiber fixing layer 3 is attached to the object (hereinafter described as a semiconductor device) for use. That is, the surface of the base material 4 facing the fiber fixing layer 3 has a release agent layer.

[0020] Examples of the main materials for this base material 4 include resin materials such as polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polypropylene, polyamide, polyimide, polycarbonate, and polyarylate, as well as glass materials such as soda glass and quartz glass. One or more of these can be used in combination.

[0021] The average thickness of the base material 4 is not particularly limited, but is preferably about 9 μm to 200 μm, and more preferably about 12 μm to 70 μm. This allows the fiber fixing layer 3 to be stably supported before peeling it off, suppresses excessive deformation, and prevents the fiber fixing layer 3 from unintentionally detaching from the base material 4.

[0022] The release agent layer provided on the fiber fixing layer 3 side of the base material 4 contains a release agent. Examples of release agents include polyolefins such as polyethylene resin, thermoplastic elastomers such as olefin-based thermoplastic elastomers, fluororesins such as tetrafluoroethylene, and mixtures thereof.

[0023] Among these, polyethylene resin and olefin-based thermoplastic elastomers are preferred release agents for use in the release agent layer. When the release agent layer is composed of such release agents, it does not contain silicone compounds that can adversely affect relays, etc. Therefore, by composing the release agent layer with polyethylene resin and olefin-based thermoplastic elastomers, it is possible to prevent the formation of an environment within the adhesive body in which silicone compounds can migrate from the release agent layer to the fiber fixing layer (adhesive layer). Furthermore, by composing the release agent layer with polyethylene resin and olefin-based thermoplastic elastomers, it becomes unnecessary to use silicone resin at the manufacturing site when manufacturing the adhesive body, thus preventing silicone compounds from adhering to the surface of the adhesive sheet substrate or release sheet substrate. In addition to the above effects, the use of olefin-based thermoplastic elastomers and polyethylene resin in the release agent layer provides excellent release properties. Therefore, the release operation can be easily performed.

[0024] <<Fiber fixing layer (adhesive layer)>> The fiber fixing layer 3 has a layered overall shape and a planar shape similar to the base material 4. It has the function of fixing the straight fibers 21 on the upper surface (one side) of the fiber fixing layer 3 by fixing the base end of the straight fibers 21 in an embedded state along its thickness direction (vertical direction).

[0025] The fiber fixing layer 3 is fixed to the straight fibers 21 by embedding the proximal ends of the straight fibers 21 into the fiber fixing layer 3 using an electrostatic flocking method described later. This ensures that the straight fibers 21 are securely fixed to the fiber fixing layer 3.

[0026] Examples of the fiber fixing layer 3 include a photocurable adhesive layer and a thermosetting adhesive layer. Examples of the photocurable adhesive layer include an ultraviolet-curable adhesive layer that hardens upon irradiation with ultraviolet light, and an electron-beam-curable adhesive layer that hardens upon irradiation with an electron beam, and may include a photopolymerization initiator, etc. Examples of the ultraviolet-curable adhesive layer or electron-beam-curable adhesive layer include an adhesive layer containing a base resin, a radiation-polymerizable compound, and a radiation polymerization initiator, etc.

[0027] Examples of the base resin contained in the photocurable adhesive layer include acrylic resins, silicone resins, polyester resins, polyvinyl acetate resins, polyvinyl ether resins, styrene elastomer resins, polyisoprene resins, polyisobutylene resins, and urethane resins, which are known as components of adhesive layers.

[0028] Among these, the base resin is preferably an acrylic resin with excellent heat resistance. The acrylic resin is preferably a polymer (homopolymer or copolymer) in which the main component as a monomer is an alkyl (meth)acrylate.

[0029] The base resin contained in the photocurable adhesive layer may be of one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

[0030] Examples of radiation-polymerizable compounds include low molecular weight compounds having two or more polymerizable carbon-carbon double bonds in one molecule that can be three-dimensionally crosslinked by irradiation with energy rays such as ultraviolet rays or electron beams. Specific examples of such compounds include those described in Japanese Patent Application Publication No. 2022-141213.

[0031] Examples of radiation polymerization initiators include those described in Japanese Patent Application Publication No. 2022-141213. The photocurable adhesive layer may contain additives such as tackifiers and crosslinking agents.

[0032] Thus, by including a photocurable component, the fiber fixing layer 3 (adhesive layer) can have its durability after curing enhanced. In particular, as will be described later, this is advantageous in manufacturing.

[0033] On the other hand, examples of thermosetting adhesive layers include adhesive layers containing a base resin and thermosetting components.

[0034] Examples of the base resin included in the thermosetting adhesive layer include the same as the base resin included in the photocurable adhesive layer described above.

[0035] The base resin contained in the thermosetting adhesive layer may be of one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

[0036] Examples of the thermosetting components included in the thermosetting adhesive layer include various thermosetting resins such as epoxy resins, phenolic resins, urea resins, urethane resins, and melamine resins.

[0037] The thermosetting component contained in the thermosetting adhesive layer may be one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected according to the purpose.

[0038] Thus, by including a thermosetting component in the fiber fixing layer 3 (adhesive layer), the durability after curing can be particularly enhanced.

[0039] The fiber fixing layer 3, which is composed of such an adhesive layer, may further contain a particulate thermal conductive material for the purpose of improving the thermal conductivity of the fiber fixing layer 3.

[0040] Furthermore, the base material 4 and the fiber fixing layer 3 described above may each contain various additives as needed, such as plasticizers, tackifiers, thickeners, fillers, antioxidants, preservatives, fungicides, dyes, and pigments.

[0041] The thermal conductivity of the fiber fixing layer 3 (adhesive layer) is not particularly limited, but is preferably 0.2 W / m·K or more and 1 W / m·K or less, and more preferably 0.4 W / m·K or more and 1 W / m·K or less. This allows the heat generated in the semiconductor device provided with the heat dissipation sheet 1 to be conducted (transferred) to the heat dissipation layer 2 side via the fiber fixing layer 3 with excellent thermal conductivity.

[0042] When the thickness (average thickness) of the fiber fixing layer 3 is T1, and the length (average length) of the portion of the straight fiber 21 embedded in the fiber fixing layer 3 is L1, it is preferable that L1 / T1 is between 0.3 and 1, and more preferably between 0.8 and 1. This allows the straight fiber 21 to be fixed more reliably and stably in an upright position.

[0043] The thickness T1 of the fiber fixing layer 3 is not particularly limited, but is preferably 10 μm or more and 1000 μm or less, and more preferably 50 μm or more and 300 μm or less. This allows the straight fibers 21 to be fixed more reliably and stably in an upright position. In particular, in the present invention, the fiber fixing layer 3 is directly attached to the object to which heat is dissipated, so it is effective to set the characteristics of the fiber fixing layer 3 as described above.

[0044] The length L1 of the portion of the straight fiber 21 embedded in the fiber fixing layer 3 is not particularly limited, but is preferably 3 μm to 1000 μm, and more preferably 10 μm to 100 μm. This ensures that the straight fiber 21 is stably fixed by the fiber fixing layer 3 in an upright position.

[0045] The elastic modulus of the fiber fixing layer 3 at room temperature (25°C) is preferably 0.1 MPa to 10 MPa, and more preferably 0.2 MPa to 9 MPa. This allows the fiber fixing layer 3 to fix the straight fibers 21 more stably and for a longer period of time, and to exhibit excellent adhesion to semiconductor devices. In particular, in the present invention, the fiber fixing layer 3 is directly attached to the object that dissipates heat, so setting the characteristics of the fiber fixing layer 3 as described above is effective.

[0046] The modulus of elasticity at room temperature can be obtained, for example, by preparing a fiber-fixed layer 3 with a width of 4 mm and a length of 20 mm in accordance with JIS K7244-4, and measuring it at room temperature using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5 °C / min.

[0047] The elastic modulus of the fiber fixing layer 3 at high temperatures (75°C) is preferably 0.01 MPa to 5 MPa, and more preferably 0.05 MPa to 4 MPa. This allows the fiber fixing layer 3 to fix the straight fibers 21 more stably and for a longer period of time even at high temperatures, and to exhibit excellent adhesion to semiconductor devices that tend to generate heat.

[0048] The modulus of elasticity at high temperatures can be obtained, for example, by preparing a fiber-fixed layer 3 with a width of 4 mm and a length of 20 mm in accordance with JIS K7244-4, and measuring it at high temperature (75°C) using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min.

[0049] The elastic modulus of the fiber-fixed layer 3 at room temperature (25°C) and the elastic modulus of the fiber-fixed layer 3 at high temperature (75°C) shall be the values ​​after curing. Even when curing is performed after attachment to a semiconductor device, the values ​​shall be those after curing.

[0050] <<Heat dissipation layer>> The heat dissipation layer 2 is provided on the substrate 4 via the fiber fixing layer 3. When a heat dissipation sheet 1 is provided in conjunction with a semiconductor device, the heat generated by the semiconductor device is transferred through the substrate 4 and the fiber fixing layer 3, and then the heat dissipation layer 2 has the function of dissipating the heat to the outside of the semiconductor device and the heat dissipation sheet 1, i.e., to the outside air.

[0051] In this invention, the heat dissipation layer 2 comprises a plurality of straight fibers 21 that have thermal conductivity, i.e., heat dissipation properties. The heat dissipation layer 2 has a planar shape, and as shown in Figure 1, the base ends of the straight fibers 21 are embedded and fixed in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3, with the tip end facing upwards (opposite side from the fiber fixing layer 3), and the layers are erected in the thickness direction.

[0052] By configuring the heat dissipation layer 2 in this way, it is possible to miniaturize the heat dissipation sheet 1, especially in the thickness direction, while increasing the contact area between the semiconductor device and the outside of the heat dissipation sheet 1, i.e., the outside air, and the heat dissipation layer 2 (straight fibers 21). As a result, the heat generated in the semiconductor device can be dissipated through the heat dissipation sheet 1 with excellent heat dissipation efficiency.

[0053] The straight fibers 21 are not particularly limited and include, for example, glass fibers, carbon fibers, polyamide fibers (nylon 6 fibers, nylon 66 fibers, nylon 46 fibers, aramid fibers, etc.), modified polyphenylene ether (modified PPE) fibers, poly-p-phenylene benzobisoxazole (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. One or more of these can be used in combination.

[0054] The straight fibers 21 are preferably such that their thermal conductivity is 0.2 W / m·K or more and 900 W / m·K or less, and more preferably 10 W / m·K or more and 900 W / m·K or less. Furthermore, their thermal emissivity is preferably 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 range, the heat generated in the semiconductor device can be dissipated through the heat dissipation sheet 1 (straight fibers 21) with better heat dissipation efficiency.

[0055] Furthermore, while the conductivity of the straight fibers 21 is not particularly limited, in applications where insulation is important, it is preferable that the electrical resistivity be 100 kΩ·m or higher. This ensures reliable insulation in the heat dissipation layer 2 when the heat dissipation sheet 1 is provided in accordance with the semiconductor device. In addition, the heat dissipation layer 2 composed of straight fibers 21 can be reliably formed using the electrostatic flocking method described later.

[0056] Considering the thermal conductivity, thermal emissivity, and electrical conductivity of the straight fiber 21 as described above, at least one of the following is preferred as the straight fiber 21: carbon fiber, aramid fiber, nylon 6 fiber, stainless steel fiber, and PBO fiber. When insulation is to be ensured, PBO fiber is preferably used.

[0057] In the heat dissipation layer 2, the length of the portion of the straight fiber 21 that protrudes from the fiber fixing layer 3 at its tip is preferably 70 μm or more and 7000 μm or less, and more preferably 150 μm or more and 5000 μm or less.

[0058] Furthermore, the straight fibers 21 are preferably 0.9 μm or more and 20 μm or less in thickness, and more preferably 4 μm or more and 20 μm or less.

[0059] Furthermore, when the length of the portion 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 to 400, and more preferably 20 to 100.

[0060] Furthermore, in a plan view of the fiber-fixed layer 3, the density of the region where the straight fibers 21 are embedded in the fiber-fixed layer 3 is 0.05 cm². 2 / cm 2 More than 0.7cm 2 / cm 2 Preferably, it is 0.1 cm 2 / cm 2 More than 0.5cm 2 / cm 2 The following is more preferable.

[0061] By setting the length L, thickness T, aspect ratio (L / T), and density of the straight fibers 21 within the specified range, it is possible to reliably reduce the thickness of the heat dissipation layer 2 and, consequently, the heat dissipation sheet 1, while dissipating the heat generated in the semiconductor device through the heat dissipation sheet 1 with superior heat dissipation efficiency.

[0062] As described above, the heat dissipation sheet 1 comprises a fiber fixing layer 3 as an adhesive layer having adhesive properties, and a heat dissipation layer 2 provided on one side of the fiber fixing layer 3 and having straight fibers 21 that have heat dissipation properties. The base ends of the straight fibers are embedded in the fiber fixing layer 3 from one side and fixed to the fiber fixing layer 3, and the other side of the fiber fixing layer 3 is used to be attached to a semiconductor device, which is an example of an object. With this configuration, the heat dissipation sheet 1 can be made even thinner. In addition, since the fiber fixing layer 3 is directly attached to the object to be heated, the heat dissipation performance is also improved. Thus, according to the present invention, it is possible to achieve both thinning and improved heat dissipation performance.

[0063] As a result, when a heat dissipation sheet 1 is provided to accommodate a miniaturized semiconductor device, it is easy to secure space for the heat dissipation sheet 1. Therefore, the overall appearance of the electronic component equipped with the heat dissipation sheet 1 can be improved, and furthermore, it can be made lighter.

[0064] Furthermore, the heat dissipation sheet 1 further includes a base material 4, which serves as a release sheet, provided on the other side (the lower side in Figure 1) of the fiber fixing layer 3, which serves as an adhesive layer. This protects the fiber fixing layer 3 with the base material 4 before it is attached to a semiconductor device, which is an example of an object, and prevents the adhesive strength of the fiber fixing layer 3 from being unintentionally reduced.

[0065] Furthermore, it is preferable that the elastic modulus of the fiber fixing layer 3 at room temperature (25°C) is 0.2 MPa or more and 9 MPa or less, the elastic modulus of the fiber fixing layer 3 at room temperature (75°C) is 0.05 MPa or more and 4 MPa or less, and the thickness T1 of the fiber fixing layer 3 is 10 μm or more and 100 μm or less. As a result, due to the synergistic effect of these factors, the straight fibers 21 can be fixed more stably and for a longer period of time both at room temperature and at high temperatures, and excellent adhesion can be achieved to semiconductor devices that tend to generate heat. In addition, durability can be improved. In particular, in the present invention, since the fiber fixing layer 3 is directly attached to the object that dissipates heat, setting the characteristics of the fiber fixing layer 3 as described above is very effective.

[0066] In such a heat dissipation sheet 1, it is preferable that the straight fibers 21 are electrostatically flocked onto the fiber fixing layer 3. Electrostatic flocking allows for the relatively easy formation of straight fibers 21 having the above-described structure. Therefore, as an example of a method for manufacturing a heat dissipation sheet 1 having a heat dissipation layer 2, the case in which electrostatic flocking is used to form the heat dissipation layer 2 composed of straight fibers 21 is described below.

[0067] (Method for manufacturing heat dissipation sheet 1) Figure 2 is a side view illustrating the manufacturing method for the heat dissipation sheet shown in Figure 1. In the following explanation, the upper part of Figure 2 will be referred to as "top" and the lower part as "bottom".

[0068] In the following, before explaining the manufacturing method of the heat dissipation sheet 1, we will first describe the heat dissipation sheet manufacturing apparatus used in the manufacturing method of the heat dissipation sheet 1.

[0069] The heat dissipation sheet manufacturing apparatus 100 shown in Figure 2 includes an electrode plate 110, a counter electrode plate 120, and a DC voltage generator 130.

[0070] The electrode plate 110 is charged with a negative charge by the DC voltage generator 130, which is used as a voltage application means.

[0071] The electrode plate 110 is provided with a holder 115 on the side (bottom surface) facing the opposing electrode plate 120. The holder 115 is configured to hold (place) the base material 4, on which the fiber fixing layer 3 is formed, with the fiber fixing layer 3 facing the opposing electrode plate 120.

[0072] The opposing electrode plate 120 is positively charged by the DC voltage generator 130, which is used as a voltage application means, and is positioned opposite the electrode plate 110.

[0073] The opposing electrode plate 120 is configured such that straight fibers 21 for forming the heat dissipation layer 2 can be placed on the surface (upper surface) facing the electrode plate 110. Note that the positive and negative terminals of the electrode plate 110 and the opposing electrode plate 120 may be reversed.

[0074] The DC voltage generator 130 is a voltage application means for applying voltage to the electrode plate 110 and the counter electrode plate 120, and is electrically connected via wiring such that the electrode plate 110 side is the negative electrode and the counter electrode plate 120 side is the positive electrode.

[0075] The heat dissipation sheet 1 is manufactured by the heat dissipation sheet manufacturing method using the heat dissipation sheet manufacturing apparatus 100 described above.

[0076] The method for manufacturing a heat dissipation sheet includes a preparation step of holding a base material 4 equipped with a fiber fixing layer 3 before hardening in a holder 115 and placing straight fibers 21 on a counter electrode plate 120; an electrostatic flocking step of charging the electrode plate 110 with a negative charge and the counter electrode plate 120 with a positive charge by operating a DC voltage generator 130, 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; and a fixing step of solidifying or hardening the fiber fixing layer 3 on which the straight fibers 21 have been implanted, thereby fixing the straight fibers 21 to the fiber fixing layer 3.

[0077] The following details each step in the manufacturing process of the heat dissipation sheet 1. [A] First, a base material 4 having a fiber fixing layer 3 before solidification or hardening is held in a holder 115, and straight fibers 21 are placed on the counter electrode plate 120 (preparation step).

[0078] In this preparation step, first, a base material 4 equipped with a fiber fixing layer 3 (adhesive layer) before solidification or hardening is prepared, and then this base material 4 is held in a holder 115 so that the fiber fixing layer 3 faces the opposing electrode plate 120. Also, the straight fibers 21 are placed on the opposing electrode plate 120.

[0079] As a result, as shown in Figure 2(a), the fiber-fixed layer 3 before solidification or hardening and the straight fibers 21 are positioned opposite each other with a space in between between the electrode plate 110 and the opposing electrode plate 120.

[0080] [B] Next, the DC voltage generator 130 is activated to charge the electrode plate 110 with a negative charge and the counter electrode plate 120 with a positive charge, 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 (implantation process).

[0081] This hair implantation process is carried out by operating a DC voltage generator 130 to apply a voltage between the electrode plate 110 and the counter electrode plate 120, thereby charging the electrode plate 110 with a negative charge and the counter electrode plate 120 with a positive charge, thereby generating an electrostatic field between the electrode plate 110 and the counter electrode plate 120.

[0082] In this process, the straight fiber 21 placed on the counter electrode plate 120 becomes positively charged due to the counter electrode plate 120 becoming positively charged. Because the electrode plate 110 is negatively charged due to the positive charge on the straight fiber 21, the straight fiber 21 flies through the electrostatic field towards the electrode plate 110.

[0083] At this time, the straight fiber 21 is elongated, but it flies along the vertical direction within the space (electrostatic field) between the electrode plate 110 and the counter electrode plate 120, with its base end facing the electrode plate 110 and its tip end facing the counter electrode plate 120.

[0084] Furthermore, the holder 115 on the electrode plate 110 side holds a base material 4 equipped with a fiber fixing layer 3 before solidification or hardening, with the fiber fixing layer 3 facing the opposing electrode plate 120. As a result, as shown in Figure 2(b), straight fibers 21 flying from the opposing electrode plate 120 side are fixed (implanted) to the side of the fiber fixing layer 3 opposite to the base material 4 by piercing (embedding) a portion of their base end into the fiber fixing layer 3.

[0085] The flight of these straight fibers 21 from the opposing electrode plate 120 toward the electrode plate 110 is carried out until the density of the straight fibers 21 implanted in the fiber fixing layer 3 reaches a predetermined density, after which the operation of the DC voltage generator 130 is stopped (see Figure 2(c)).

[0086] [C] Next, the straight fibers 21 are fixed to the fiber fixing layer 3 by solidifying or hardening the fiber fixing layer 3 in which the straight fibers 21 have been implanted (fixing step).

[0087] As a result, before the fiber fixing layer 3 solidifies or cures, the straight fibers 21 are fixed in a state of being embedded in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3 at their base ends. As a result, on the side opposite to the base material 4 of the fiber fixing layer 3, as shown in Fig. 2(c), a heat dissipation layer 2 is formed in which the straight fibers 21 stand upright in the vertical direction with the tip sides of the straight fibers 21 facing downward (opposite to the fiber fixing layer 3).

[0088] This fixing step is carried out by heating the fiber fixing layer 3 when the fiber fixing layer 3 is composed of a curable or thermosetting adhesive layer. Also, when the fiber fixing layer 3 is composed of a photocurable adhesive layer, this fixing step is carried out by irradiating the fiber fixing layer 3 with light. Due to the solidification or curing of the fiber fixing layer 3, the straight fibers 21 are fixed by the fiber fixing layer 3 in a state where the base ends of the straight fibers 21 are embedded in the fiber fixing layer 3 along the thickness direction (vertical direction) of the fiber fixing layer 3. Through the above steps, the heat dissipation sheet 1 is manufactured. [[ID=B]]

[0089] <Second Embodiment> Next, a second embodiment of the heat dissipation sheet of the present invention will be described. Fig. 3 is a side view showing a second embodiment of the heat dissipation sheet of the present invention.

[0090] Hereinafter, the heat dissipation sheet 1 of the second embodiment will be described focusing on the differences from the heat dissipation sheet 1 of the first embodiment, and the description of the same matters will be omitted.

[0091] The heat dissipation sheet 1 has 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 a plan view of the heat dissipation sheet 1. In the first embodiment, it can be said that the entire area is the first region 2A in a plan view of the heat dissipation sheet 1.

[0092] The density of the straight fibers 21 in the first region 2A is not particularly limited, but is 10,000 fibers / cm 2 or more and 1,000,000 fibers / cm 2 or less.

[0093] The density of straight fibers 21 in the second region 2B is not particularly limited, but is 0 fibers / cm 2 Over 10,000 strands / cm 2 The following applies:

[0094] In this embodiment, the first region 2A and the second region 2B are elongated in shape, extending from the foreground to the depth direction in Figure 3. Therefore, the second region 2B can be described as a groove extending from the foreground to the depth direction in Figure 3.

[0095] This configuration allows for improved airflow in the second region 2B. Specifically, it allows for the formation of airflow in the second region 2B. As a result, the heat from the straight fibers 21 in the first region 2A is efficiently dissipated by the air flowing into the second region 2B. Therefore, the overall heat dissipation performance of the heat dissipation sheet 1 can be further enhanced.

[0096] Note that the formation locations, number, and shape of the first region 2A and the second region 2B are not limited to the configuration shown in the figure.

[0097] The heat dissipation sheet 1 of this embodiment can be manufactured by arranging masks corresponding to the first region 2A and the second region 2B below the fiber fixing layer 3 in Figure 2(b) and operating the DC voltage generator 130.

[0098] Furthermore, regions where the fiber-fixed layer 3 exists and regions where it does not exist may be formed, corresponding to the first region 2A and the second region 2B.

[0099] Furthermore, in the heat dissipation sheet 1 of the first embodiment, the fiber fixing layer 3 may be removed along with the straight fibers 21 corresponding to the first region 2A and the second region 2B.

[0100] The heat dissipation sheet of the present invention has been described above, but the present invention is not limited thereto.

[0101] For example, in the heat dissipation sheet of the present invention, each component can be replaced with any component capable of performing a similar function, or any component can be added. Furthermore, an adhesive layer may be provided on the side of the fiber fixing layer 3 that is attached to the object. [Industrial applicability]

[0102] According to the present invention, it is possible to provide a heat dissipation sheet that has excellent heat dissipation properties and is miniaturized, particularly in the thickness direction. Therefore, the present invention has industrial applicability. [Explanation of Symbols]

[0103] 1. Heat dissipation sheet 2 Heat dissipation layer 2A 1st area 2B 2nd area 3. Fiber immobilization layer 4 Base material 21 Straight fibers 100 Heat dissipation sheet manufacturing equipment 110 Electrode plate 115 Holder 120 Counter electrode plate 130 DC Voltage Generator T1 Thickness L1 Length

Claims

1. An adhesive layer having adhesive properties, The adhesive layer comprises a heat dissipation layer provided on one side of the adhesive layer and having straight fibers that have heat dissipation properties, The straight fibers are fixed to the adhesive layer by embedding their base ends from one side of the adhesive layer. The other side of the adhesive layer is used to adhere to an object, When the thickness of the adhesive layer is T1, and the length of the portion of the straight fibers embedded in the adhesive layer is L1, then L1 / T1 is 0.3 or more and 1 or less. The aforementioned T1 is 10 μm or more and 1000 μm or less. In a plan view, it has a first region where the straight fibers are present and a second region where the straight fibers are not present. A heat dissipation sheet characterized in that the adhesive layer is present in the first region and the second region in a plan view.

2. The heat dissipation sheet according to claim 1, wherein the elastic modulus of the adhesive layer at room temperature is 0.1 MPa or more and 10 MPa or less.

3. The heat dissipation sheet according to claim 1, wherein the elastic modulus of the adhesive layer at high temperatures is 0.01 MPa or more and 5 MPa or less.

4. The heat dissipation sheet according to any one of claims 1 to 3, wherein the thermal conductivity of the adhesive layer is 0.2 W / m·K or more and 1 W / m·K or less.

5. The heat dissipation sheet according to any one of claims 1 to 3, wherein the adhesive layer comprises a thermosetting component.

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

7. The heat dissipation sheet according to any one of claims 1 to 3, further comprising a release sheet provided on the other side of the adhesive layer.

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