JP4530283B2 - Thermally conductive sheet and method for producing the same - Google Patents

Description

  The present invention relates to a thermally conductive sheet used when an electronic component generating a large amount of heat is mounted on a cooling unit such as a heat sink or a radiator, and a method for manufacturing the same.

Conventionally, when electronic parts with large heat generation such as power transistors and power modules (hereinafter referred to as exothermic electronic parts) are attached to heat sinks and radiators, heat generated by exothermic electronic parts is eliminated. Thermally conductive material used to efficiently transmit heat to heat sinks and radiators is a sheet of heat-dissipating grease in which liquid metal is mixed with metal oxide, etc., and metal oxide in heat-dissipating compound or silicone rubber. Thermally conductive heat dissipating members molded into the above have been proposed (Patent Documents 1 and 2 below).
JP-A-9-207275 JP-A-10-183110

  However, grease, compounds and heat dissipation sheets made of liquid silicone resin and silicone rubber fill the interior of electronic equipment, where low-molecular siloxanes volatilize when the heat dissipation member is heated by heat generated by the operation of heat-generating electronic components. Recently, the volatile low molecular weight silicone is likely to cause a so-called silicone trouble and has been avoided. Therefore, in recent years, many heat radiating members made of materials other than silicone have been used.

  In order to solve the above-mentioned problems, the present invention uses a polymer composition that does not have the risk of breaching out low molecular weight substances such as monomers and oligomers, has high thermal conductivity, good dimensional stability, is soft, and has load characteristics. Provided are a heat conductive sheet and a method for producing the same, which are less likely to crack.

The thermally conductive sheet of the present invention is a thermally conductive sheet for mounting in the gap between the heat-generating electronic component and the radiator, and the inner layer or one surface of the sheet is an acrylic heavy material containing a thermally conductive filler. It is a solventless adhesive elastic body layer mainly composed of coalesced, and at least one surface layer portion selected from the upper and lower surfaces of the sheet is at least one selected from acrylic polymer, urethane acrylate, epoxy acrylate, and polyester acrylate. A solvent-free cured thin film layer containing a polymer, wherein the cured thin film layer is integrated on one side or both sides of the elastic body layer .

The method for producing a heat conductive sheet according to the present invention is a method for producing a heat conductive sheet mainly composed of an acrylic polymer blended with a heat conductive filler, from an upper release film and a lower release film. The surface of at least one selected film is uniformly coated with a solvent-free cured thin film layer material containing at least one polymer selected from acrylic polymer, urethane acrylate, epoxy acrylate, and polyester acrylate. When one film has the cured thin film material layer, the other film is a release film, and an acrylic polymer in which a thermally conductive filler is blended between the upper film and the lower film A sheet base material of the main component is supplied, formed into a sheet of a predetermined thickness, and then only the surface layer portion of the sheet is cured. By peeling the film after, the inner layer or one surface is tacky elastic solventless, on at least one surface portion selected from the top and bottom surfaces of the sheet, by integrating the cured film layer, A heat conductive sheet according to claim 1 is produced.

  According to the present invention, a heat conductive sheet mainly composed of an acrylic polymer containing a heat conductive filler, the inner layer or one surface of the sheet is a solventless adhesive elastic body, and the sheet By integrating a cured thin film layer on at least one surface layer selected from the upper and lower surfaces, there is no risk of breaching out low molecular weight substances such as monomers and oligomers, and high thermal conductivity and dimensional stability. It is possible to provide a heat conductive sheet that is good, soft, has good load characteristics, and is less likely to crack, and a method for producing the same. Further, by forming a cured thin film layer on at least one side surface layer portion or embedding a sheet-like reinforcing material, the elongation when the product is peeled off from the release paper is considerably reduced, and the handleability is improved. Furthermore, when the ratio of the modified acrylate and the acrylic monomer or the ratio of the modified acrylate and the acrylic polymer is set to an appropriate ratio, the sheet does not break when the sheet is bent.

  The heat conductive sheet of the present invention is mainly composed of an acrylic polymer blended with a heat conductive filler. Here, the main component means 20% by mass or more when the entire organic component is 100% by mass. By using an acrylic polymer as a base resin, there is no fear that a low molecular weight substance such as a monomer or an oligomer will be bleached out. This is a property of the acrylic polymer itself.

  Moreover, the inner layer or one surface of the heat conductive sheet of the present invention is a solvent-free adhesive elastic body. Here, the term “solvent-free” means that no organic solvent is positively added. The water | moisture content of the grade which adsorb | sucks the water | moisture content in air may be contained. Thereby, when it affixes on heat generating bodies, such as an electronic component, it can deform | transform freely in a thickness direction and can be affixed on a heat generating body without a clearance gap, heat conductivity is high, and heat dissipation can also be made high. A cured thin film layer is integrated with at least one surface layer portion selected from the upper and lower surfaces of the sheet. As a result, the inner layer or one surface is soft like a fresh rice bowl, but the surface layer has a hard thin film layer, so that it becomes easy to handle.

  The method for producing a heat conductive sheet according to the present invention is a method in which a thin film of a material for a heat conductive cured thin film layer is attached to the surface layer of a soft sheet base material by a so-called transfer method, and only the surface layer of the sheet is cured. A heat conductive sheet is obtained. That is, a heat conductive cured thin film layer material is uniformly applied in a thin film shape on a release resin film, and a sheet base material of an acrylic polymer main component containing a heat conductive filler is supplied to the application surface. Then, from above, the release resin film or the heat conductive cured thin film layer material is uniformly applied in a thin film shape to form a sheet having a predetermined thickness, and then the sheet. The film is peeled off after curing only the surface layer part.

  The thickness of each of the cured thin film layer or the thermally conductive cured thin film layer integrated on one side or both sides of the thermal conductive sheet is preferably in the range of 0.001 mm to 0.50 mm, the total thickness of the thermal conductive sheet Is preferably 0.10 mm to 10 mm. Further, a sheet-like reinforcing material is embedded in the vicinity of the upper and lower single-sided surface layers, but the thickness of the heat conductive sheet is equal to or greater than the thickness of the sheet-like reinforcing material. preferable.

Hereinafter, each material and manufacturing process will be described.
(1) Thermally conductive sheet base material mainly composed of an acrylic polymer blended with a thermally conductive filler An acrylic polymer as a main component of the thermal conductive sheet base material includes an acrylic group as a functional group, An oligomer or polymer having at least two methacrylic groups alone, an acrylic group as a functional group, a mixture of an oligomer and a monomer having at least two methacrylic groups, an acrylic group as a functional group, and at least two methacrylic groups A mixture of one or more polymers and monomers, a polymer having at least two acrylic groups or methacryl groups as functional groups, a mixture of oligomers and monomers, and the like are preferably used.

The thermally conductive sheet base material is an acrylic polymer, and is a blend of 50 parts by mass to 3000 parts by mass of a thermally conductive substance with respect to 100 parts by mass, and preferably the filling amount of the thermally conductive substance is 500 parts by mass. It is preferable that it is a part-2500 mass parts. The viscosity of the blend in that case is preferably in the range of 10,000 to 3000000 cP.
(2) Thermally conductive filler As the thermally conductive filler to be blended in the thermally conductive sheet base material of the present invention, metals such as aluminum, copper and silver, metal oxides such as alumina, magnesia and silica, aluminum nitride and boron nitride One or two or more powders, fibers, needles, flakes, spheres, etc. selected from silicon nitride and the like. In the present invention, a metal oxide is preferred. The thermally conductive filler may be surface-treated with a known silane coupling agent selected according to the material. The filler preferably has an average particle diameter of 0.2 to 100 [mu] m in the case of particles, and is preferably in a range generally conforming to this for other shapes.
(3) Material of cured thin film layer The material of the cured thin film layer of the present invention is urethane acrylate, epoxy acrylate, or polyester acrylate as an oligomer or polymer having at least two acrylic groups and methacryl groups . These can be appropriately used as a commercially available simple substance or a mixture of two or more kinds . The material for the thin film cured layer is solventless, and the viscosity thereof is preferably 50 to 20000 cP, more preferably 1000 to 10,000 cP.
(4) Film with cured thin film layer The creation of the cured thin film layer is performed by applying the cured thin film layer material onto the resin film whose surface has been previously released by the knife coater method, bar coater method, gravure coater method, multi-stage roll coater method, etc. A film with a uniform thin film applied is prepared.
(5) Transfer integration In the present invention, the surface of the cured thin film layer uniformly formed is filled with a heat conductive sheet base material, and after the base material is cured, the film is peeled off, A method of transferring and integrating the cured thin film layer material on the surface is preferable. The molding method includes press molding, coating molding, calendar molding, and the like, but any processing method can be arbitrarily selected depending on the viscosity of the compound.
(6) Sheet-like reinforcing material The sheet-like reinforcing material is included in the inner layer of the heat conductive sheet and reinforces the sheet to suppress significant deformation. Examples of the sheet-like reinforcing material include glass fiber. Carbon fiber and other inorganic fibers, polyester fibers, nylon fibers and other synthetic resin fibers such as plain weave (Plain), twill weave (Swil), satin weave (Satin), leno weave (Leno), and weave weave (Mock Lene) A woven or non-woven fabric. It may be surface-treated with a known silane coupling agent selected according to these materials. It is preferable that the sheet-like reinforcing material of the present invention is completely contained in the inner layer or one side so as not to be exposed from the inner layer or one side of the heat conductive sheet. When the reinforcing material is exposed on the surface, the heat conductive sheet becomes uneven, and the heat generating electronic component and the heat sink and the heatsink are not sufficiently adhered to each other, creating a gap between the components, and efficiently generating the heat generated by the heat generating electronic component. It often becomes difficult to transmit to a heat sink or heat radiator.
(7) Material of thermally conductive cured thin film layer The material of the thermally conductive cured thin film layer according to a preferred embodiment of the present invention is an oligomer having at least two acrylic groups or methacryl groups, or urethane as a polymer. There are acrylate, epoxy acrylate, and polyester acrylate. These are usually commercially available, and a single substance or a mixture of two or more kinds can be suitably used. Further, the thermally conductive material blended in the cured thin film layer is one or two selected from metals such as aluminum, copper and silver, metal oxides such as alumina, magnesia and silica, aluminum nitride, boron nitride and silicon nitride. It is a substance such as powdery, fibrous, needle-like, flake-like, spherical, etc. more than seeds. In the present invention, the particle diameter of the metal oxide is preferably 0.2 to 8 μm. The heat conductive material may be surface-treated with a known silane coupling agent selected according to the respective materials. The material for the thin film cured layer is solvent-free, and the viscosity thereof is preferably 50 to 20000 cP, more preferably 1000 to 10,000 cP.
(8) Film with thermally conductive cured thin film layer The thermally conductive cured thin film layer is prepared by applying a thermally conductive cured thin film layer material onto a resin film that has been previously subjected to a release treatment using a knife coater method, a bar coater method, or a gravure. A film with a uniform thin film applied is prepared by a coater method, a multi-stage roll coater method or the like. Next, the surface of the uniformly formed material of the thermally conductive thin film layer is filled with a base material of an acrylic polymer main component blended with a thermally conductive filler, and after the composition is cured, the release treatment is performed. A method of peeling off the film and transferring the heat conductive cured thin film layer onto the surface of the heat conductive sheet and integrating them is preferable. The molding method includes press molding, coating molding, calendar molding, and the like, but any processing method can be arbitrarily selected depending on the viscosity of the compound. In any case, the film on which the cured thin film layer is placed is preferably a polyester film surface-treated with a fluorine compound or a silicone compound, or a polypropylene film.
(9) Release film For the release film, a fluorine film, a polyester film surface-treated with a silicone compound, a polypropylene film, a fluorine film, or the like is appropriately selected and used.
(10) Protective film It is preferable that the other surface of the heat conductive sheet without the cured thin film layer is covered with an embossed protective film or the like. An embossed film is a film having a surface with irregularities. Depending on the difference in adhesive strength of the heat conductive sheet, the unevenness density is adjusted and used appropriately. Is that of such sheet has been subjected to ship drugs surface. The material may be anything as long as it is a resin film, but a polyethylene resin or polypropylene resin film having a thickness of about 30 μm to 80 μm is preferable. The unevenness on the surface is preferably different by 120 μm or more.

  FIG. 1A is a cross-sectional view showing an embodiment of a thermally conductive sheet according to the present invention. As shown in FIG. 1A, the thermally conductive sheet is composed of a solventless adhesive elastic body layer 1 mainly composed of an acrylic polymer blended with a thermally conductive filler, and a cured thin film blended with a thermally conductive filler. And layer 2. That is, the thin-film cured layer 2 is formed on the single-sided surface layer portion of the solventless adhesive elastic body layer 1. FIG. 1B shows an example in which a cured thin film layer 2 is formed on both surface layers of a solventless adhesive elastic body layer 1.

  FIG. 2A is a cross-sectional view showing an embodiment of another thermally conductive sheet according to the present invention. As shown in FIG. 2A, the thermally conductive sheet is composed of a solventless adhesive elastic body layer 1 mainly composed of an acrylic polymer blended with a thermally conductive filler, a sheet-like reinforcing material 3, and a surface layer thereof. It consists of a cured thin film layer 2 containing a thermally conductive filler. The sheet-like reinforcing material 3 is embedded in the solventless adhesive elastic body layer 1.

  FIG. 2B is a cross-sectional view showing an example of still another thermally conductive sheet according to the present invention. As shown in FIG. 2B, the thermally conductive sheet is a solventless adhesive elastic body layer 1 mainly composed of an acrylic polymer blended with a thermally conductive filler, a sheet-like reinforcing material 3, and its surface layer. And a cured thin film layer 2 on the back surface of the solventless adhesive elastic body layer 1. The sheet-like reinforcing material 3 uses a network-like structure made of polyester fiber, heat-resistant nylon fiber, aramid fiber, cotton fiber, etc., but polyester fiber or heat-resistant nylon fiber is preferable from the viewpoint of heat resistance.

[Measuring method]
Next, the measurement method of each test measured by the Example and comparative example of this invention is demonstrated.
(1) Elongation In this measurement, the lateral elongation (degree of deformation) of the sheet was measured. Using a cutting machine accurately from a test sheet with a thickness of 0.5 mm, half-cut on the release sheet (does not cut the release sheet, only the test sheet made of a heat conductive sheet), and length: 25 mm, width The test sheet was peeled off from the release sheet with a finger and taken out, and accurately measured to obtain the elongation of the sample sheet.
(2) Hardness Using a test sheet having a thickness of 3.0 mm, the hardness was measured according to JIS-K7312 (physical test method for thermosetting polyurethane elastomer molding).
(3) Load The load referred to here is a compressive force when the sheet is compressed and deformed. The purpose of measuring the load is to indicate the degree of compressive deformation of the sheet when the cured thin film is included. The higher the load, the more difficult it is to deform. For measurement, a test sheet having a thickness of 3.0 mm is cut into a rectangular shape of 25 mm in length and 25 mm in width, and then bonded to the center of an aluminum plate (length: 27 mm, width: 27 mm, height: 3 mm) almost exactly. . Next, the load was measured by compressing the test sheet to 50% at a speed of 5 mm / min with an apparatus in which a load cell of 200 kgf was attached to MODEL310N (compression load measuring apparatus) manufactured by Aiko Engineering Co., Ltd.
(4) Thermal resistance value in the thickness direction of the entire sheet The thermal resistance value was measured with a test sheet having a thickness of 0.5 mm. The thermal resistance measuring device 10 is as shown in FIG. 3 (plan view seen from above) and FIG. 4 (side sectional view). First, a sample 11 punched into a predetermined shape is prepared, and this is referred to as a transistor 12. It was inserted between the radiator 13 (15 is a radiation fin) and attached. For the attachment, a M3 screw 14 was tightened with a predetermined torque (5 kg-cm) using a torque screwdriver. After the attachment, DC10V, 2A (20 W) was applied to the transistor 12, and after 3 minutes, the transistor temperature To and the radiator temperature Tf were measured by a temperature sensor attached at predetermined positions. Next, it calculated from the temperature of two points by an equation. Transistor: 2SC2245 Fuji Electric Co., Ltd., radiator: 40CH104L-90-K, manufactured by Ryosan Co., Ltd., temperature sensor: 2SC1-OHK300, manufactured by Chino Co., Ltd. It calculated | required with the thermal-resistance calculation formula.
Thermal resistance calculation formula θ = (Tc−Tf) / PC
θ: Thermal resistance value (° C / W)
Tc: transistor temperature (° C.)
Tf: Heatsink temperature (° C)
PC: Electric power applied to transistor (5) Evaluation method of presence / absence of cracking Judgment was made by whether or not the test sheet would break along a metal sheet having a diameter of 4 mm along with a test sheet having a thickness of 0.5 mm.
(6) Adhesive force It was set as the measurement by JIS-Z-0237 (adhesive tape / adhesive sheet test method).
(7) Detachability In this test, the ease of removal was measured when the sheet was compressed and deformed. A test sheet having a thickness of 3.00 mm was cut into a rectangular shape with a length of 50 mm and a width of 50 mm, and then bonded to the center of an aluminum plate (length: 55 mm, width: 55 mm, height: 3 mm) almost exactly. Next, the load was released by compressing the test sheet to 50% (1.50 mm) at a speed of 5 mm / min with an apparatus in which a load cell of 200 kgf was attached to MODEL310N (compression load measuring device) manufactured by Aiko Engineering Co., Ltd. Later, it was judged whether the aluminum plate could be removed by hand.

  Next, examples and comparative examples will be described.

1. Test-1 (Examples 1-4, Comparative Example 1)
(1) Preparation of thermal conductive sheet base material 100 parts by mass of acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer) and 20 parts by mass of acrylic monomer (FA-511A / product name, manufactured by Hitachi Chemical Co., Ltd.) 300 parts by mass of aluminum oxide (AS30 / product name, manufactured by Showa Denko), 2 parts by mass of iron black, vulcanizing agent (t-amylperoxy-2-ethylhexanate / chemical name, manufactured by Kayaku Akzo) 1.0 The heat conductive sheet base material was created by kneading the mass part with a mixer. The thermal conductivity is 0.8 W / mK.
(2) Preparation of cured thin film layer As a material of the cured thin film layer, urethane acrylate (Aronix M-1200 / product name, manufactured by Toagosei Co., Ltd.) is coated on a polyester film having a thickness of 0.10 mm which has been subjected to fluorine release treatment. A thin film was uniformly applied to a thickness of 2 μm using a machine to prepare a film with a cured thin film layer. Hereinafter, this film is referred to as “film 1”.
(3) Release film As the release film, a polyester film having a thickness of 0.10 mm and surface-treated with a fluorine compound was used.
(4) Preparation of sheet-like reinforcing material The sheet-like reinforcing material is made so that oil and fat, dirt, etc. do not adhere to the surface of a polyester fiber mesh (C33 A2-100E11 / product name, thickness 0.16 mm, manufactured by Unitika Glass Fiber Co., Ltd.). And cut into a predetermined size.

Example 1
After a heat conductive sheet base material is placed on the film 1, a release film is placed on the upper part, and after being sandwiched, it is heated / pressed press molded at 120 ° C. for 30 minutes, and the thickness is 0.5 mm. A sheet (A1) in which a cured thin film layer was integrated on one side having a thickness of 3.0 mm was prepared.

(Example 2)
After placing the sheet-like reinforcing material on the film 1 and placing the heat conductive sheet base material, the release film is placed on the film 1 to form a sandwich, and then heated and pressure press-molded at 120 ° C. for 30 minutes to obtain a thickness of 0. A sheet (A2) in which a sheet-like reinforcing material having a thickness of 5 mm and a thickness of 3.0 mm was included and a cured thin film layer was integrally formed on one side was prepared.

(Example 3)
After the heat conductive sheet base material is placed on the film 1, the film 1 is placed, sandwiched, and heated and pressed under pressure at 120 ° C. for 30 minutes, on both sides having a thickness of 0.5 mm and a thickness of 3.0 mm. A sheet (A3) in which the cured thin film layer was integrally formed was prepared.

Example 4
After placing the sheet-like reinforcing material on the film 1 and placing the heat conductive sheet base material, the film 1 is placed on the film 1 to form a sandwich, and heated and pressure-pressed at 120 ° C. for 30 minutes, thickness 0.5 mm And a sheet (A4) in which a sheet-shaped reinforcing material having a thickness of 3.0 mm was included and a cured thin film layer was integrally formed on both sides.

(Comparative Example 1)
After placing the heat conductive sheet base material on the release film, and then putting the same release film in a sandwich state, it was heated and pressed under pressure at 120 ° C. for 30 minutes, and the thickness was 0.5 mm. A 3.0 mm sheet (B1) was prepared.

  The results are shown in Table 1.

  As is apparent from Table 1, the sheet having the cured thin film layer integrally formed on the surface was excellent in handleability. Further, by providing the surface reinforcing layer, the elongation when the sheet was peeled from the release paper could be considerably reduced. Furthermore, when a thin film cured layer was prepared by mixing a modified acrylate and an acrylic monomer or a mixture of a modified acrylate and an acrylic polymer, the elongation when the sheet was peeled off was almost zero. Also, the sheet did not break when bent.

  Compared with Comparative Example 1, Examples 1 to 5 had a considerably small elongation when the sheet was peeled from the release paper, and the handleability was good.

2. Test-2 (Examples 5 to 12 and Comparative Example 2)
(1) Preparation of heat conductive sheet base material A heat conductive sheet base material was prepared in the same manner as in Test-1.
(2) Creation of a film having a cured thin film layer In order to test by changing the material of the cured thin film layer integrated with the surface layer portion, the following film 2 to film 9 were created [film 2] urethane acrylate (Aronix M- 1200 / product name (manufactured by Toagosei Co., Ltd.) was formed on a polyester film having a thickness of 0.10 mm which had been subjected to a fluorine release treatment, and a film 2 was formed by uniformly applying a thin film to a thickness of 2 μm using a coating machine.
[Film 3] Film 3 is prepared by uniformly applying a thin film to a thickness of 2 μm with a coating machine on a polyester film with a thickness of 0.10 mm obtained by subjecting epoxy acrylate (8101 / trade name, manufactured by Nippon Iupika Co., Ltd.) to a fluorine release treatment. did.
[Film 4] Film 4 in which a polyester acrylate (M-8060 / trade name, manufactured by Toagosei Co., Ltd.) is coated with a thin film uniformly to a thickness of 2 μm with a coating machine on a polyester film having a thickness of 0.10 mm subjected to fluorine release treatment. It was created.
[Film 5] A solution obtained by uniformly mixing 80 parts by mass of urethane acrylate (Aronix M-1200 / product name, manufactured by Toagosei Co., Ltd.) and 20 parts by mass of phenoxy acrylate (Osaka Organic Chemical Co., Ltd.) is subjected to fluorine release treatment. A film 5 in which a thin film was uniformly applied to a thickness of 2 μm by a coating machine on a polyester film having a thickness of 0.10 mm was prepared.
[Film 6] Thickness obtained by subjecting a solution in which 80 parts by mass of epoxy acrylate (8101 / trade name, manufactured by Nippon Iupika Co., Ltd.) and 20 parts by mass of phenoxy acrylate (Osaka Organic Chemical Co., Ltd.) were uniformly mixed to a fluorine mold release treatment A film 6 was prepared by uniformly applying a thin film with a thickness of 2 μm on a 0.10 mm polyester film with a coating machine.
[Film 7] A solution in which 80 parts by mass of polyester acrylate (M-8060 / trade name, manufactured by Toagosei Co., Ltd.) and 20 parts by mass of phenoxy acrylate (Osaka Organic Chemical Co., Ltd.) were uniformly mixed was subjected to a fluorine release treatment. A film 7 in which a thin film was uniformly applied to a thickness of 2 μm with a coating machine on a polyester film having a thickness of 0.10 mm was prepared.
[Film 8] A solution obtained by uniformly mixing 80 parts by mass of an acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer Co., Ltd.) and 20 parts by mass of phenoxyacrylate (Osaka Organic Chemical Co., Ltd.) was subjected to fluorine release treatment. A film 8 in which a thin film was uniformly applied to a thickness of 2 μm on a polyester film having a thickness of 0.10 mm with a coating machine was prepared.
[Film 9] A solution obtained by uniformly mixing 80 parts by mass of an acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer Co., Ltd.) and 20 parts by mass of urethane acrylate (Aronix M-1200 / product name, manufactured by Toagosei Co., Ltd.) A film 9 in which a thin film was uniformly applied to a thickness of 2 μm by a coating machine on a 0.10 mm thick polyester film subjected to a fluorine release treatment was prepared.
[Release Film] As the release film, a polyester film having a thickness of 0.10 mm and surface-treated with a fluorine compound was used.

(Example 5)
After a heat conductive sheet base material is placed on the film 2 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A5) in which a cured thin film layer was integrated on one side of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 6)
After a heat conductive sheet base material is placed on the film 3 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A6) in which a cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 7)
After a heat conductive sheet base material is placed on the film 4 and then a release film is placed on the top to form a sandwich, after heating and pressure press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A7) in which a cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 8)
After a heat conductive sheet base material is placed on the film 5 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A8) in which a cured thin film layer was integrated on one side of 0.5 mm and a thickness of 3.0 mm was prepared.

Example 9
After a heat conductive sheet base material is placed on the film 6 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A9) in which a cured thin film layer was integrated on one side of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 10)
After a heat conductive sheet base material is placed on the film 7 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A10) in which a cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 11)
After a heat conductive sheet base material is placed on the film 8 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A11) in which a cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 12)
After a heat conductive sheet base material is placed on the film 9, a release film is placed on the top to form a sandwich, and after heating and pressure press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A12) in which a cured thin film layer was integrated on one side of 0.5 mm and a thickness of 3.0 mm was prepared.

(Comparative Example 2)
After placing the heat conductive sheet base material on the release film and putting the same release film on top to make a sandwich, heat and pressure press molding at 120 ° C for 30 minutes and thickness 0.5mm and thickness A 3.0 mm sheet (B2) was prepared.

  The results are shown in Table 2.

  As is apparent from Table 2, the example product of the present invention was able to reduce the elongation of the sheet when the sheet of each example was peeled off from the release film by integrating the cured thin film layer. Thereby, the deformation | transformation of the sheet | seat was able to be prevented.

  In addition, a sheet integrated with a cured thin film layer made of a mixture of modified acrylate and acrylic monomer or acrylic polymer (8: 2) has an elongation of almost “0” when the sheet is peeled off from the release film. Yes, the sheet did not break even when bent. This confirmed that the handleability was good. Among these, sample Nos. 9 to 12 were used. A9 to A12 were highly resistant to cracking when the sheet was bent.

  In addition, the sample Nos. A6 to A8 formed a cured thin film layer using only the modified acrylate. Since the modified acrylate has many functional groups in the molecule, the crosslink density of the cured thin film layer is increased and the cured thin film layer is easily broken. In A9 to A12, when the acrylic monomer or acrylic rubber was added to the modified acrylate to lower the crosslink density of the cured thin film layer, the cured thin film layer became flexible and hardly cracked.

  Sample No. of Comparative Example 2 B2 is an example in which a sample was prepared only with a heat conductive sheet base material. Sample No. of Comparative Example 2 B2 was not preferable because the sheet stretched and deformed. On the other hand, the sample Nos. The sheets A9 to A12 were deformed in the thickness direction, but did not extend in the lateral direction, and the form stability was good.

3. Test-3 (Examples 13 to 20 and Comparative Examples 3 and 4)
(1) Preparation of heat conductive sheet base material A heat conductive sheet base material was prepared in the same manner as in Test-1.
(2) Film with heat-conducting cured thin film layer In order to test by changing the material of the heat-conducting cured thin film layer integrated with the surface layer part, film 14 was created from the following film 11 [film 11]
Urethane acrylate (Aronix M-1200 / product name, manufactured by Toagosei Co., Ltd.) 100 parts by mass, aluminum oxide (AL-43L / product name, manufactured by Showa Denko Co., Ltd.) 200 parts by mass, iron black 2 parts by mass, vulcanizing agent (T-aluminum peroxy-2-ethylhexanate / chemical name, manufactured by Kayaku Akzo Co., Ltd.) After thoroughly mixing 1 part by mass with a mixer, it was coated on a 0.10 mm thick polyester film that had been subjected to fluorine release treatment. A film 11 having a uniform thin film applied to a thickness of 2 μm was prepared using a machine.
[Film 12]
100 parts by mass of polyester acrylate (M-6100 / trade name, manufactured by Toagosei Co., Ltd.) and 200 parts by mass of aluminum oxide (AL-43L / product name, manufactured by Showa Denko KK), 2 parts by mass of iron black, vulcanizing agent ( (T-aluminum peroxy-2-ethylhexanate / chemical name, manufactured by Kayaku Akzo Co., Ltd.) After mixing 1 part by mass with a mixer, a coating machine was applied on a polyester film having a thickness of 0.10 mm that had been subjected to fluorine release treatment. A film 12 having a uniform thin film applied to a thickness of 2 μm was prepared.
[Film 13]
30 parts by mass of acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer Co., Ltd.) and 70 parts by mass of urethane acrylate (Aronix M-1100 / product name, manufactured by Toagosei Co., Ltd.) and aluminum oxide (AL-43L / product name / 200 parts by mass of Showa Denko Co., Ltd., 2 parts by mass of iron black, and 1 part by mass of a vulcanizing agent (t-aluminum peroxy-2-ethylhexanate / chemical name, manufactured by Kayaku Akzo Co., Ltd.) were sufficiently mixed with a mixer. Thereafter, a film 13 was prepared by uniformly applying a thin film to a thickness of 2 μm with a coating machine on a polyester film having a thickness of 0.10 mm subjected to a fluorine release treatment.
[Film 14]
30 parts by mass of acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer) and 70 parts by mass of polyester acrylate (M-6100 / product name, manufactured by Toagosei Co., Ltd.) and aluminum oxide (AL-43L / product name, Showa) After fully mixing 200 parts by mass of Denko Co., Ltd.), 2 parts by mass of iron black, and 1 part by mass of a vulcanizing agent (t-aluminum peroxy-2-ethylhexanate / chemical name, manufactured by Kayaku Akzo Co., Ltd.) with a mixer. Then, a film 14 in which a thin film was uniformly applied to a thickness of 2 μm by a coating machine on a 0.10 mm-thick polyester film subjected to fluorine release treatment was prepared.
[Film 15]
A polyester film having a thickness of 0.10 mm and surface-treated with a fluorine compound was used.
[Creation of sheet reinforcement]
The sheet-like reinforcing material is cut to a predetermined size so that oils and dirt do not adhere to the surface of the polyester fiber mesh (C33 A2-100E11 / product name, thickness 0.16 mm, manufactured by Unitika Glass Fiber Co., Ltd.). Created.
[Release film]
As the release film, a 0.10 mm thick polyester film surface-treated with a fluorine compound was used.

(Example 13)
After placing the sheet-like reinforcing material on the film 11 and placing the heat conductive sheet base material, and further putting the release film on the upper part to make a sandwich state, after heating and pressure press molding at 120 ° C. for 30 minutes The upper and lower films were peeled off to create a sheet (A13) in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Example 14)
After a heat conductive sheet base material is placed on the film 11 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A14) in which a thermally conductive thin film layer was integrated on one side of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 15)
After placing the sheet-like reinforcing material on the film 12, after placing the heat conductive sheet base material, and further putting the release film on the top to make a sandwich state, after heating and pressure press molding at 120 ° C for 30 minutes The upper and lower films were peeled off to prepare a sheet (A15) in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Example 16)
After a heat conductive sheet base material is placed on the film 12 and a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A16) was prepared in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Example 17)
After placing the sheet-like reinforcing material on the film 13 and placing the heat conductive sheet base material, and further putting the release film on the upper part to make a sandwich state, after heating and pressure press molding at 120 ° C. for 30 minutes The upper and lower films were peeled off to produce a sheet (A17) in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Example 18)
After a heat conductive sheet base material is placed on the film 13 and then a release film is placed on the top to form a sandwich, after heating and press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A18) in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Example 19)
After placing the sheet-like reinforcing material on the film 14 and then placing the heat conductive sheet base material, and then putting the release film on the upper part to make a sandwich state, after heating and pressure press molding at 120 ° C. for 30 minutes The upper and lower films were peeled off to produce a sheet (A19) in which a thermally conductive thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Example 20)
After a heat conductive sheet base material is placed on the film 14 and then a release film is placed on the top to form a sandwich, after heating and pressure press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (A20) in which a thermally conductive cured thin film layer was integrated on one side having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Comparative Example 3)
After placing the sheet-like reinforcing material on the film 15 and placing the heat conductive sheet base material, and further putting the release film on the upper part to make a sandwich state, after heating and pressure press molding at 120 ° C. for 30 minutes The upper and lower films were peeled off to prepare a sheet (B3) having a thickness of 0.5 mm and a thickness of 3.0 mm.

(Comparative Example 4)
After a heat conductive sheet base material is placed on the film 15 and a release film is placed on the top to form a sandwich, after heating and pressure press molding at 120 ° C. for 30 minutes, the upper and lower films are peeled off. A sheet (B4) having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Comparative Example 5)
A heat conductive sheet base material is placed on the release film later, a release film is placed on the upper part to form a sandwich, 120 ° C for 30 minutes heating and pressure press molding, and then the upper and lower films are peeled off. A sheet (B5) having a thickness of 0.5 mm and a thickness of 3.0 mm was prepared.

(Comparative Example 6)
A vulcanizing agent (t-amyl peroxy) was added to 10 parts by mass of acrylic polymer (JDX-P1020 / product name, manufactured by Johnson Polymer Co., Ltd.) and 90 parts by mass of ester acrylate (Aronix M-8530 / product name, manufactured by Toagosei Chemical Co., Ltd.). (2-ethylhexanate / chemical name, manufactured by Kayaku Akzo Co., Ltd.) 1.0 part by mass was kneaded with a mixer. After making it into a sandwich state with a release film, it was subjected to heating and pressure press molding at 120 ° C. for 30 minutes, and then the upper and lower films were peeled off to prepare a sheet (B6) having a thickness of 0.5 mm and a thickness of 3.0 mm.

  The above results are shown in Table 3-4.

  As apparent from Table 3-4, Sample Nos. A13-20 was able to make the adhesive force almost "0" by forming a cured thin film layer. Thereby, it is possible to easily disconnect each other even after being sandwiched between the heat-generating electronic component and the radiator. Furthermore, the thermal resistance value (° C./W) was further improved by imparting thermal conductivity to the cured thin film layer.

FIG. 1A is a cross-sectional view showing an embodiment of a thermal conductive sheet according to the present invention, which is an example in which a cured thin film layer is formed on one surface of a solventless adhesive elastic body layer. FIG. 1B shows an example in which a cured thin film layer is formed on both sides. FIG. 2A is a cross-sectional view showing an embodiment of another thermally conductive sheet according to the present invention, in which a sheet-like reinforcing material is embedded inside the surface of the solventless adhesive elastic layer, and a cured thin film is formed on the surface layer thereof. This is an example in which a layer is formed. FIG. 2B shows an example in which a cured thin film layer is formed on both surfaces. FIG. 3 is a plan view showing thermal resistance measurement methods in the examples of the present invention and comparative examples. FIG. 4 is a side sectional view of the same.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solvent-free adhesive elastic body layer 2 Hardened thin film layer 3 Sheet-like reinforcing material 10 Thermal resistance measuring device 11 Sample 12 Transistor 13 Radiator 14 Screw 15 Radiation fin To Transistor temperature Tf Radiator temperature

Claims (10)

A thermally conductive sheet for mounting in a gap between a heat-generating electronic component and a radiator ,
The inner layer or one side of the sheet is a solventless adhesive elastic body layer mainly composed of an acrylic polymer blended with a heat conductive filler ,
At least one surface layer portion selected from the upper and lower surfaces of the sheet is a solventless cured thin film layer containing at least one polymer selected from acrylic polymer, urethane acrylate, epoxy acrylate, and polyester acrylate,
A thermally conductive sheet , wherein the cured thin film layer is integrated on one side or both sides of the elastic layer .   The thickness of the said heat conductive sheet is the range of 0.10-10 mm, The thickness of the said thin film hardened layer is the range of 0.001-0.50 mm, The heat conductive sheet of Claim 1. The heat conductive sheet according to claim 1 or 2, wherein the sheet constituting the inner layer or one side has a viscosity in the range of 1 x 10 ^{4 to} 3 x 10 ⁶ cP.   The thermally conductive sheet according to any one of claims 1 to 3, wherein the thermally conductive sheet is blended in a range of 50 to 3000 parts by mass of a thermally conductive filler with respect to 100 parts by mass of an acrylic polymer. .   The thermal conductivity of the thermal conductive sheet is 0.5 to 5.0 W / m · K, and the thermal conductivity of the thermally conductive cured thin film layer is 0.20 to 2.5 W / m · K. The heat conductive sheet in any one of Claims 1-4.   The heat conductive sheet according to any one of claims 1 to 5, wherein the hardness of the acrylic polymer main component sheet containing the heat conductive filler is in a range of 5 to 95 with an ASKER C hardness meter.   The heat conductive sheet according to any one of claims 1 to 6, further comprising a sheet-like reinforcing material embedded in one surface layer portion of the upper and lower surfaces of the sheet.   The thermally conductive sheet according to claim 7, wherein the sheet-like reinforcing material is embedded in a range of more than 0 mm and a depth of 1.00 mm from the surface, and the thickness of the sheet is 0.10 mm to 10.0 mm.   The thermally conductive sheet according to claim 7 or 8, wherein the sheet-like reinforcing material is a network-like structure formed of at least one fiber selected from synthetic fibers and natural fibers. A method for producing a thermally conductive sheet mainly composed of an acrylic polymer blended with a thermally conductive filler,
On the surface of at least one film selected from the upper release film and the lower release film, a solventless cured thin film layer material containing at least one polymer selected from acrylic polymer, urethane acrylate, epoxy acrylate, and polyester acrylate is provided. Apply a uniform thin film to form a cured thin film material layer,
When one film has the cured thin film material layer, the other film is a release film,
Between the upper film and the lower film, supplying a sheet base material of an acrylic polymer main component blended with a heat conductive filler, molded into a sheet of a predetermined thickness,
Then, after curing only the surface layer portion of the sheet, by peeling off the film,
The inner layer or one surface is tacky elastic solventless, on at least one surface portion selected from the top and bottom surfaces of the sheet, by integrating the cured film layer, according to claim 1 A method for producing a thermally conductive sheet, characterized in that a thermally conductive sheet is produced.

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