Multi-layer structure

Abstract

To provide a multilayer structure which can suppress adhesion of a heat dissipation sheet on a sheet member arranged on the heat dissipation sheet.SOLUTION: A multilayer structure 1 includes a film 20, a heat dissipation sheet 10 which is mounted on one main surface 20a of the film 20 and contains heat conductive particles and a resin, and spacers 30 which are arranged side by side with the heat dissipation sheet 10 on the one main surface 20a of the film, wherein the spacer 30 regulates contact between the sheet member arranged on the heat dissipation sheet 10, and the heat dissipation sheet 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multilayer structure provided with a heat dissipation sheet.

Background Art

[0002] A multilayer structure in which devices are temporarily attached in a row to a long tape-shaped film is known as a conventional technique (see, for example, Patent Document 1). In this multilayer structure, a device is peeled off from the film by a device mounting feeder having a knife edge, and suction, transfer, and adhesion are performed by a transfer head. Thereby, the assembly of the device can be automated.

[0003] A heat dissipation sheet mainly has a function of being disposed between a heat generating body such as a semiconductor package and a heat dissipation body such as aluminum or copper, and quickly transferring the heat generated by the heat generating body to the heat dissipation body (see, for example, Patent Documents 2 and 3). Similar to the above device, the assembly of the heat dissipation sheet can be automated by packaging the heat dissipation sheet in a multilayer structure in which the heat dissipation sheet is temporarily attached in a row to a long tape-shaped film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the multilayer structure of the heat dissipation sheet is in the form of taping in which a long tape-shaped film with the heat dissipation sheet temporarily attached in a row is wound around a reel, there has been a problem that the heat dissipation sheet temporarily attached to the film may adhere to the back surface of the film. Therefore, an object of the present invention is to provide a multilayer structure of a heat dissipation sheet that can suppress the adhesion of the heat dissipation sheet to the back surface of the film even when films on which the heat dissipation sheet is placed overlap each other by winding a long tape-shaped film around a reel or the like.

Means for Solving the Problems

[0006] As a result of intensive studies, the present inventor has found that the above problems can be solved by providing a predetermined spacer on the film on which the heat dissipation sheet is placed, and has completed the following invention. The present invention provides the following [1] to

[17] . [1] A multilayer structure comprising a film, a heat dissipation sheet placed on one main surface of the film and containing heat conduction particles and a resin, and a spacer arranged on the one main surface of the film so as to be aligned with the heat dissipation sheet, wherein the spacer regulates the contact between a sheet member disposed on the heat dissipation sheet and the heat dissipation sheet. [2] The multilayer laminate is wound in a roll shape, and the spacer regulates the contact between the main surface of the film opposite to the one main surface of the film and the heat dissipation sheet. The multilayer structure according to [1] above. [3] The multilayer structure according to [1] or [2] above, wherein the spacer is placed on the one main surface of the film. [4] The multilayer structure according to any one of [1] to [3] above, wherein the difference (d1 - d2) between the thickness (d1) of the spacer and the thickness (d2) of the heat dissipation sheet is 25 to 1,750 μm. [5] The multilayer structure according to any one of [1] to [4] above, wherein the 25% compressive strength of the spacer is 30 to 300 kPa. [6] The film is a long tape-shaped film having a length direction and a width direction, A plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval. The spacer is the multilayer structure according to any one of [1] to [5] above, provided continuously or intermittently in the length direction on one or both sides of the heat dissipation sheets arranged in the length direction. [7] The film is a long tape-shaped film having a length direction and a width direction. A plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval. The spacer is the multilayer structure according to any one of [1] to [6] above, surrounding each of the heat dissipation sheets. [8] The film is a long tape-shaped film having a length direction and a width direction. A plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval. The spacer is the multilayer structure according to any one of [1] to [5] above, provided in the interval between adjacent heat dissipation sheets. [9] The multilayer structure according to any one of [1] to [8] above, wherein the spacer is a foam.

[10] The multilayer structure according to [9] above, wherein the foam is a polyolefin-based resin foam or a polyurethane-based resin foam.

[11] The multilayer structure according to any one of [1] to

[10] above, wherein the Asker C hardness of the surface of the heat dissipation sheet is 15 or more.

[12] The multilayer structure according to any one of [1] to

[11] above, wherein the tensile strength of the heat dissipation sheet is 0.05 MPa or more.

[13] The multilayer structure according to any one of [1] to

[12] above, wherein the 30% compression strength of the heat dissipation sheet is 2000 kPa or less.

[14] The multilayer structure according to any one of [1] to

[13] above, wherein the resin of the heat dissipation sheet is an elastomer resin, a silicone resin, or an acrylic resin.

[15] The multilayer structure according to any one of [1] to

[14] above, wherein the heat conduction particles of the heat dissipation sheet include at least one kind of heat conduction particle selected from the group consisting of boron nitride and aluminum nitride.

[16] The heat conduction particles include a heat conductive plate-shaped filler. The multilayer structure according to any one of [1] to

[15] above, wherein the major axis of the heat conductive plate-like filler is oriented at an angle of 60° or more with respect to the main surface of the heat dissipation sheet.

[17] The multilayer structure according to any one of [1] to

[16] above, wherein the heat dissipation sheet can be picked up by vacuum adsorption.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a multilayer structure capable of suppressing the adhesion of the heat dissipation sheet to the sheet member disposed on the heat dissipation sheet.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, a multilayer structure 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1(a) is a perspective view of the multilayer structure according to an embodiment of the present invention, and FIG. 1(b) is a cross-sectional view taken along line AA of the multilayer structure according to an embodiment of the present invention shown in FIG. 1(a). Note that the multilayer structure of the present invention is not limited to the multilayer structure 1 according to an embodiment of the present invention described below.

[0010] The multilayer structure 1 according to an embodiment of the present invention includes a film 20, a heat dissipation sheet 10 placed on one main surface (first main surface 20a) of the film 20 and containing heat conduction particles and resin, and a spacer 30 arranged on one main surface (first main surface 20a) of the film 20 so as to be aligned with the heat dissipation sheet 10. The spacer 30 restricts the contact between the sheet member disposed on the heat dissipation sheet 10 and the heat dissipation sheet 10.

[0011] In the present embodiment, the multilayer structure 1 is wound around a reel 40 and wound into a roll shape. Therefore, on the heat conductive sheet 10 of the multilayer structure 1 in the present embodiment, the film 20 is disposed as a sheet member, and the spacer 30 restricts the heat dissipation sheet 10 on one main surface 20a of the wound film 20 from contacting the main surface 20b (second main surface 20b, also referred to as "back surface") on the opposite side of the film 20. With such a configuration, the spacer 30 prevents the heat dissipation sheet 10 from adhering to the second main surface (back surface) 20b of the film 20 even when the multilayer structure 1 is wound and the films 20 are overlapped.

[0012] As shown in FIG. 1(a), the film 20 is a long tape-shaped film having a length direction (L direction) and a width direction (W direction). A plurality of heat dissipation sheets 10 are placed on the film 20, and the plurality of heat dissipation sheets 10 are arranged side by side in the length direction (L direction) at a predetermined interval. The spacer 30 continuously extends in the length direction (L direction) on both sides of the heat dissipation sheets 10 arranged in the length direction (L direction). Thereby, when the films 20 on which the heat dissipation sheets 10 are placed are overlapped, it is possible to more reliably suppress the heat dissipation sheet 10 from adhering to the back surface (second main surface 20b) of the film 20.

[0013] [Heat dissipation sheet] As described above, the heat dissipation sheet 10 contains heat conductive particles and a resin.

[0014] (Heat conductive particles) The heat conductive particles are not particularly limited as long as they are particles with high thermal conductivity. However, from the viewpoint of effectively improving the thermal conductivity of the heat dissipation sheet with a small usage amount, the heat conductive particles are preferably heat conductive plate-like fillers. The heat conductive plate-like filler is a heat conductive plate-like filler having a shape with a maximum length / thickness greater than 2.0. Examples of the material of the heat conductive filler include carbides, nitrides, oxides, hydroxides, metals, carbon-based materials, and the like.

[0015] Examples of the carbides include silicon carbide, boron carbide, aluminum carbide, titanium carbide, tungsten carbide, and the like. Examples of the nitrides include silicon nitride, boron nitride, aluminum nitride, gallium nitride, chromium nitride, tungsten nitride, magnesium nitride, molybdenum nitride, lithium nitride, and the like. Examples of the oxides include iron oxide, silicon oxide (silica), aluminum oxide (alumina) (including hydrated products of aluminum oxide such as boehmite), magnesium oxide, titanium oxide, cerium oxide, zirconium oxide, and the like. Further, as the oxides, transition metal oxides such as barium titanate, and furthermore, those doped with metal ions, such as indium tin oxide, antimony tin oxide, and the like can be mentioned. Examples of the hydroxides include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and the like. Examples of the metals include copper, gold, nickel, tin, iron, or their alloys. Examples of the carbon-based materials include carbon black, graphite, diamond, fullerene, carbon nanotube, carbon nanofiber, nano horn, carbon microcoil, nano coil, and the like. Among those described above, it is preferably at least one selected from the group consisting of boron nitride and aluminum nitride.

[0016] These thermally conductive plate-like fillers can be used alone or in combination of two or more. From the viewpoint of thermal conductivity, it is preferably at least one of boron nitride and exfoliated graphite. Further, in applications where electrical insulation is required, boron nitride is more preferable.

[0017] The average particle size of the thermally conductive plate-like filler is not particularly limited, but is preferably 1 to 400 μm, more preferably 5 to 300 μm. The average particle size of the thermally conductive plate-like filler is determined by laser diffraction particle size distribution measurement and represents the particle size at which the integrated particle amount is 50% on a volume basis. The aspect ratio of the thermally conductive plate-like filler is 2 or more as described above, but is preferably 3 or more. Here, the aspect ratio of the plate-like thermally conductive particles means the ratio of the maximum length to the thickness of the particles (maximum length / thickness). The aspect ratio may be determined as an average value by observing a sufficient number (for example, 250) of thermally conductive particles with a scanning electron microscope.

[0018] As the thermally conductive plate-like filler, commercially available products or processed products thereof can be used. Examples of commercially available products include commercially available products of boron nitride particles. Specific examples of commercially available products of boron nitride particles include the "PT" series (for example, "PT-110", etc.) manufactured by Momentive Performance Materials Japan, the "Show BN UHP" series (for example, "Show BN UHP-1", etc.) manufactured by Showa Denko KK, "XGP", "SGP", "MGP", and "GP" manufactured by Denka Co., Ltd., and the like.

[0019] When the heat-conductive particles contain heat-conductive plate-like fillers, in the heat dissipation sheet 10, the heat-conductive plate-like fillers in the resin are preferably oriented at an angle of 60° or more with respect to the major surface 10a of the heat dissipation sheet 10 in the direction of their major axes. When the major axes of the heat-conductive particles are oriented at an angle of 60° or more with respect to the major surface 10a of the heat dissipation sheet 10, the thermal conductivity in the thickness direction of the heat dissipation sheet 10 can be increased. From the viewpoint of increasing the thermal conductivity in the thickness direction of the heat dissipation sheet 10, it is more preferable that the major axes of the heat-conductive plate-like fillers are oriented at an angle of 70° or more with respect to the major surface 10a of the heat dissipation sheet 10, and it is even more preferable that they are oriented at an angle of 80° or more. The method for obtaining the above angle is not particularly limited. For example, in the heat dissipation sheet 10, a thin film section of the central portion in the thickness direction is prepared in the direction in which the heat-conductive plate-like fillers are most oriented, usually in the direction parallel to the resin flow direction during molding, and the heat-conductive plate-like fillers are observed with a scanning electron microscope (SEM) at a magnification of 3,000 times. The above angle can be obtained by measuring the angle formed by the major axis of the observed heat-conductive plate-like fillers and the surface constituting the major surface 10a in the heat dissipation sheet 10. In this specification, an angle of 60° or more means that the average value of the values measured as described above is an angle of 60° or more, and it does not deny the existence of heat-conductive particles with an orientation angle of less than 60°. When the formed angle exceeds 90°, its supplementary angle is taken as the measured value.

[0020] In the heat conduction sheet of the present invention, fillers other than the heat-conductive plate-like fillers may be used as the heat-conductive particles, and the heat-conductive plate-like fillers and fillers other than the heat-conductive plate-like fillers may be contained. Further, the heat conduction sheet may contain only fillers other than the heat-conductive plate-like fillers without containing the heat-conductive plate-like fillers as the heat-conductive particles. Examples of fillers other than the heat-conductive plate-like filler include spherical fillers. The material of the spherical filler is as described above, but preferably, alumina, carbon black, natural silica, dry synthetic silica, wet synthetic silica, calcium carbonate (patelite), glass beads, silica beads, spherical metal fillers, etc. may be mentioned. These fillers may be used alone or in combination of two or more kinds.

[0021] The content of the heat-conductive particles in the heat-dissipating sheet 10 is preferably 50 to 1,000 parts by mass, more preferably 100 to 500 parts by mass, and even more preferably 150 to 450 parts by mass with respect to 100 parts by mass of the resin.

[0022] (Resin) The resin is not particularly limited, and various resins such as polyolefin resins, polyamide resins, polyester resins, polystyrene resins, polyvinyl chloride resins, polyvinyl acetate resins, ABS resins, acrylic resins, silicone resins, and elastomer resins can be used. Among these resins, at least one resin selected from the group consisting of acrylic resins, silicone resins, and elastomer resins is preferable, and elastomer resins are more preferable. By using an acrylic resin or a silicone resin, appropriate surface adhesion strength of the heat-dissipating sheet to the film can be obtained without forming an adhesive layer on the film. In addition, by using an elastomer resin, mechanical strength such as the tensile strength of the heat-dissipating sheet can be improved.

[0023] Examples of the elastomer resin include acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber, ethylene-propylene rubber, natural rubber, polyisoprene rubber, polybutadiene rubber, hydrogenated polybutadiene rubber, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, and the like. Among these elastomer resins, hydrogenated polybutadiene rubber is preferred.

[0024] The type of the acrylic resin is not particularly limited, but it is a polymer obtained by polymerizing monomers including acrylate, methacrylate, and both of them. Hereinafter, one or both of acrylate and methacrylate are collectively referred to as (meth)acrylate. The acrylic resin usually has a structural unit derived from an alkyl (meth)acrylate. As the alkyl (meth)acrylate, those having 12 or less carbon atoms in the alkyl group are usually used, and those having 3 to 12 carbon atoms in the alkyl group are preferably used. Specifically, alkyl (meth)acrylates such as n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, and n-decyl (meth)acrylate can be mentioned. Only one type of acrylic resin may be used, or a plurality of types may be used in combination.

[0025] The type of silicone resin is not particularly limited, and either a condensation-curing type silicone resin or an addition-reaction curing type silicone resin may be used, but an addition-reaction curing type silicone resin is preferred. The silicone resin is preferably obtained by crosslinking a silicone compound with a crosslinking agent and curing it. As the silicone compound, it is preferable to use an organopolysiloxane having two or more alkenyl groups such as a vinyl group, and an organopolysiloxane having vinyl groups at both ends is more preferable. Examples of the organopolysiloxane having vinyl groups at both ends include vinyl-terminated polydimethylsiloxane, vinyl-terminated polyphenylmethylsiloxane, vinyl-terminated dimethylsiloxane-diphenylsiloxane copolymer, vinyl-terminated dimethylsiloxane-phenylmethylsiloxane copolymer, vinyl-terminated dimethylsiloxane-diethylsiloxane copolymer, and the like. The crosslinking agent is not limited as long as it can crosslink the above-described silicone compound, and examples thereof include compounds having two or more hydrosilyl groups (SiH). Among them, a polyorganosiloxane having two or more hydrosilyl groups (hereinafter also referred to as "hydrosilyl group-containing polyorganosiloxane") is preferable. Examples of the hydrosilyl group-containing polyorganosiloxane include methylhydrosiloxane-dimethylsiloxane copolymer, polymethylhydrosiloxane, polyethylhydrosiloxane, methylhydrosiloxane-phenylmethylsiloxane copolymer, and the like. These may or may not contain a hydrosilyl group at the terminal, and for example, both ends may be blocked by a trimethylsilyl group, a triethylsilyl group, or the like. The silicone resin may be used alone or in combination of multiple types.

[0026] Further, the resin preferably includes a resin that is liquid at normal temperature. Further, it may include both a resin that is liquid at normal temperature and a solid resin, but it is more preferably composed only of a resin that is liquid at normal temperature. By including a liquid resin, the kneading load with the heat-conductive particles during the production of the heat dissipation sheet can be reduced, so that the heat-conductive particles are easily dispersed uniformly and the thermal conductivity is improved. Note that the resin that is liquid at normal temperature means a resin that is liquid under the conditions of 20°C and 1 atmospheric pressure (1.01×10 -1 MPa). As the liquid resin, for example, the liquid forms of the above-described resins can be used. Suitable specific examples include liquid acrylonitrile-butadiene rubber, liquid ethylene-propylene copolymer, liquid natural rubber, liquid polyisoprene rubber, liquid polybutadiene rubber, liquid hydrogenated polybutadiene rubber, liquid styrene-butadiene block copolymer, liquid hydrogenated styrene-butadiene block copolymer, liquid acrylic resin, liquid silicone resin, and the like.

[0027] (Thermal conductivity of the heat dissipation sheet) From the viewpoint of improving the heat dissipation performance of the heat dissipation sheet 10, the thermal conductivity in the thickness direction of the heat dissipation sheet 10 is preferably 3 W / m·K or more, more preferably 5 W / m·K or more, and still more preferably 8 W / m·K or more. Further, the thermal conductivity in the thickness direction of the heat dissipation sheet 10 is usually 100 W / m·K or less, preferably 70 W / m·K or less. The thermal conductivity of the heat dissipation sheet 10 can be measured by the method described in the examples.

[0028] (Asker C hardness of the surface of the heat dissipation sheet) The Asker C hardness of the surface of the heat dissipation sheet 10 is, for example, 10 or more, preferably 15 or more, more preferably 25 or more, and even more preferably 35 or more. When the Asker C hardness of the surface of the heat dissipation sheet 10 is 15 or more, when the heat dissipation sheet 10 is picked up by vacuum adsorption using a vacuum nozzle, it is possible to suppress the occurrence of scratches on the surface of the heat dissipation sheet. The Asker C hardness of the surface of the heat dissipation sheet 10 is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less. When the Asker C hardness of the surface of the heat dissipation sheet 10 is 70 or less, the flexibility of the heat dissipation sheet 10 is improved. The Asker C hardness of the surface of the heat dissipation sheet 10 can be measured by the method described in the examples.

[0029] (Tensile strength of the heat dissipation sheet) The tensile strength of the heat dissipation sheet 10 is, for example, 0.03 MPa or more, preferably 0.05 MPa or more. When the tensile strength of the heat dissipation sheet 10 is 0.05 MPa or more, when the heat dissipation sheet 10 is picked up by vacuum adsorption using a vacuum nozzle, it is possible to suppress the deformation of the heat dissipation sheet. From such a viewpoint, the tensile strength of the heat dissipation sheet 10 is more preferably 0.1 MPa or more, even more preferably 0.2 MPa or more, and even more preferably 0.45 MPa or more. Also, from the viewpoint of the flexibility of the heat dissipation sheet 10, the tensile strength of the heat dissipation sheet 10 is preferably 2.0 MPa or less, more preferably 1.5 MPa or less, and even more preferably 1.0 MPa or less. The tensile strength of the heat dissipation sheet 10 can be measured by the method described in the examples.

[0030] (30% compression strength of the heat dissipation sheet) The 30% compression strength of the heat dissipation sheet 10 is, for example, 2500 kPa or less, preferably 2000 kPa or less. When the 30% compression strength of the heat dissipation sheet 10 is 2000 kPa or less, the flexibility of the heat dissipation sheet 10 becomes even better. From such a viewpoint, the 30% compression strength of the heat dissipation sheet 10 is more preferably 1500 kPa or less, and even more preferably 1000 kPa or less. Also, from the viewpoint of improving the handleability of the heat dissipation sheet 10, the 30% compression strength of the heat conduction sheet of the present invention is preferably 100 kPa or more, more preferably 200 kPa or more, and even more preferably 500 kPa or more. The 30% compression strength of the heat dissipation sheet 10 can be measured by the method described in the examples.

[0031] (Size of the heat dissipation sheet) The size of the heat dissipation sheet 10 can be appropriately changed according to the device mounted on the heat dissipation sheet 10. The length of the heat dissipation sheet in the longitudinal direction (L direction) is usually 0.5 to 100 mm, and the length in the width direction (W direction) is usually 0.5 to 100 mm. Also, the thickness of the heat dissipation sheet 10 is usually 50 to 10,000 μm, preferably 100 to 8,000 μm. The shape of the heat dissipation sheet 10 is not particularly limited, but a rectangular shape or a square shape etc. is preferable.

[0032] (Surface adhesion strength) The surface adhesion strength of the heat dissipation sheet 10 to the film 20 is preferably 1.0 N / mm or less. When the surface adhesion strength of the heat dissipation sheet 10 to the film 20 is 1.0 N / mm or more, the heat dissipation sheet 10 placed on the film 20 can be more reliably picked up from the film 10 by vacuum adsorption. From such a viewpoint, the surface adhesion strength of the heat dissipation sheet 10 to the film 20 is more preferably 0.8 N / mm or less, and even more preferably 0.6 N / mm or less. Further, the surface adhesion strength of the heat dissipation sheet 10 to the film 20 is preferably 0.05 N / mm or more. When the surface adhesion strength of the heat dissipation sheet 10 to the film 20 is 0.05 N / mm or more, the heat dissipation sheet 10 can be more reliably temporarily adhered to the film 20. From such a viewpoint, the surface adhesion strength of the heat dissipation sheet 10 to the film 20 is more preferably 0.07 N / mm or more, and even more preferably 0.09 N / mm or more. The surface adhesion strength of the heat dissipation sheet 10 to the film 20 can be measured by the method described in the examples.

[0033] (Method for manufacturing heat dissipation sheet) The method for manufacturing the heat conduction sheet of the present invention is not particularly limited. For example, it includes a kneading step of kneading a resin and heat conduction particles to produce a heat conductive resin composition, and a laminating step of laminating the heat conductive resin composition to produce a laminate.

[0034] In this embodiment, the heat conduction sheet 1 is obtained by using a method including the following <kneading step> and <laminating step>. Furthermore, if necessary, it is also possible to use a <slicing step> and a <crosslinking step>.

[0035] <Kneading step> Knead the heat conduction particles and the resin to produce a heat conductive resin composition. The above kneading is preferably performed, for example, by kneading a resin and heat conduction particles under heating using a twin-screw kneader such as a plastomill or a twin-screw extruder, whereby a heat conductive resin composition in which the heat conduction particles are uniformly dispersed in the resin can be obtained.

[0036] <Laminating Process> In the laminating process, the thermally conductive resin composition obtained in the kneading process is laminated in multiple layers to produce a laminate. As a lamination method, for example, after laminating the thermally conductive resin composition produced in the kneading process in multiple layers to produce a laminate, hot pressing is performed. Then, further, the processes of cutting, laminating, and the above hot pressing are repeated to increase the number of layers of the laminate. A method can be used.

[0037] Thus, according to the method of narrowing the length in the width direction of the thermally conductive resin layer by multiple moldings, the molding pressure in each molding can be made smaller compared to the case of performing molding in one time. Therefore, phenomena such as the destruction of the laminated structure due to molding can be avoided.

[0038] As another lamination method, for example, an extruder equipped with a multi-layer forming block can be used, and the multi-layer forming block can be prepared to obtain a laminate by co-extrusion molding.

[0039] Specifically, the thermally conductive resin composition obtained in the kneading process is introduced into both the first extruder and the second extruder, and the thermally conductive resin composition is simultaneously extruded from the first extruder and the second extruder. The thermally conductive resin compositions extruded from the first extruder and the second extruder are sent to a feed block. In the feed block, the thermally conductive resin compositions extruded from the first extruder and the second extruder merge. Thereby, a two-layer body in which the thermally conductive resin composition is laminated can be obtained. Next, the above two-layer body is transferred to a multi-layer forming block, and after being divided into a plurality of parts along a plurality of surfaces that are parallel to the extrusion direction and perpendicular to the lamination surface, they are laminated to produce a laminate. In this lamination process, when the thermally conductive particles contain thermally conductive plate-like fillers, the long axis of the thermally conductive plate-like fillers can be oriented along one direction in the plane direction of each layer of the laminate. Therefore, the thermally conductive plate-like fillers can be oriented at a high angle of 60° or more with respect to the main surface of the heat dissipation sheet by going through the slicing process described later.

[0040] <Slicing process> The laminate obtained in the lamination process is laminated to a desired height as needed, pressure is applied to bond them together, and then sliced in a direction parallel to the lamination direction to produce the heat dissipation sheet 10.

[0041] <Crosslinking process> In the crosslinking process, the heat dissipation sheet 10 is irradiated with ionizing radiation to crosslink the heat dissipation sheet 10. Thereby, the adhesiveness of the heat dissipation sheet 10 can be suppressed. Examples of the ionizing radiation include light, γ-rays, electron beams, etc. The irradiation dose of the ionizing radiation is preferably 50 to 800 kGy at an accelerating voltage of 100 to 1,000 kV, and more preferably 100 to 700 kGy at an accelerating voltage of 200 to 800 kV. The crosslinking process is preferably performed when the resin is an elastomer resin.

[0042] By going through the above process, a heat dissipation sheet 10 in which the major axis of the heat conduction particles is oriented at an angle of 60° or more with respect to the main surface 10a of the heat dissipation sheet 10 can be obtained.

[0043] [Spacer] As described above, the spacer 30 regulates the contact between the heat dissipation sheet 10 and the sheet member (in this embodiment, the film 20 itself) disposed on the film.

[0044] (Thickness) The thickness (d1) of the spacer 30 is preferably greater than the thickness (d2) of the heat dissipation sheet. By making the thickness (d1) greater than the thickness (d2), it becomes easier to regulate the contact between the sheet member (film 20) disposed on the film 20 and the heat dissipation sheet 10. The difference (d1 - d2) between the thickness (d1) of the spacer 30 and the thickness (d2) of the heat dissipation sheet is not particularly limited as long as it can regulate the contact between the sheet member (film 20) and the heat dissipation sheet 10. The difference (d1 - d2) between the thickness (d1) of the spacer 30 and the thickness (d2) of the heat dissipation sheet is, for example, 25 to 2,500 μm, preferably 25 to 1,750 μm. When the difference (d1 - d2) between the thickness (d1) of the spacer 30 and the thickness (d2) of the heat dissipation sheet is 25 μm or more, contact between the heat dissipation sheet 10 and the sheet member (film 20) can be prevented. For example, when the film 20 with the heat dissipation sheet 10 placed thereon is wound around the reel 40, it is possible to more reliably suppress the heat dissipation sheet 10 from adhering to the back surface (main surface 20b) of the film 20. When the difference (d1 - d2) between the thickness (d1) of the spacer 30 and the thickness (d2) of the heat dissipation sheet is 1,750 μm or less, the occurrence of winding defects such as winding nests and peakings can be suppressed, and the film 20 provided with the spacer 30 can be wound around the reel 40 or the like. From such a viewpoint, the difference (d1 - d2) between the thickness (d1) of the spacer 30 and the thickness (d2) of the heat dissipation sheet is more preferably 40 to 1,600 μm, and even more preferably 50 to 1,500 μm.

[0045] (Width of the spacer) The width of the spacer 30 is not particularly limited as long as it can regulate the contact between the sheet member (film 20) disposed on the film 20 and the heat dissipation sheet 10, but is, for example, 1 to 500 mm.

[0046] (25% Compressive strength) The 25% compressive strength of the spacer 30 is not particularly limited as long as it can regulate the contact between the sheet member (film 20) disposed on the film 20 and the heat dissipation sheet 10. The 25% compressive strength of the spacer 30 is, for example, 30 to 400 kPa, preferably 30 to 300 kPa. When the 25% compressive strength of the spacer 30 is 30 kPa or more, when the film 20 provided with the spacer 30 is wound around the reel 40, it is possible to more reliably suppress the spacer 30 from being crushed and the heat dissipation sheet 10 from adhering to the back surface 20b of the film 20. When the 25% compressive strength of the spacer 30 is 300 kPa or less, it is possible to suppress the occurrence of winding defects such as winding nests and peakings, and wind the film 20 provided with the spacer 30 around the reel 40. Further, the film 20 provided with the spacer 30 can be stably unwound from the reel 40. From such a viewpoint, the 25% compressive strength of the spacer 30 is more preferably 35 to 270 kPa, and even more preferably 40 to 250 kPa. The 25% compressive strength of the spacer 30 can be measured by the method described in the examples.

[0047] (Foam) The material of the spacer 30 is not particularly limited as long as it can regulate the contact between the sheet member (film 20) disposed on the film 20 and the heat dissipation sheet 10. From the viewpoint of being able to easily increase the thickness of the spacer 30 and the viewpoint of being able to make the spacer 30 light, the spacer 30 is preferably a foam. From the viewpoints of excellent elasticity, relatively high strength, and low manufacturing cost, among foams, polyolefin-based resin foams and polyurethane-based resin foams are preferable, and polyurethane-based resin foams are more preferable.

[0048] [Film] The film 20 is not particularly limited as long as it is normally used in the form of taping of the device. Films normally used in the form of taping include, for example, polyester films such as polystyrene film and polyethylene terephthalate film, polycarbonate film, polyolefin films such as polyethylene film and polypropylene film. Among these films, polyethylene terephthalate film and polyethylene film are preferred, and polyethylene terephthalate film is more preferred.

[0049] (Thickness of the film) At the knife edge, in order to enable the heat dissipation sheet 10 to be more reliably peeled off from the film 20, it is preferable that the film 20 can follow the shape of the knife edge used when peeling the heat dissipation sheet 10 from the film 20. Also, in order to make the film 20 follow the shape of the knife edge, tension is applied to the film 20, so it is preferable that the film 20 is not easily cut by the knife edge. From such a viewpoint, the thickness of the film 20 is, for example, 5 to 250 μm, preferably 20 to 200 μm, more preferably 50 to 200 μm, and even more preferably 50 to 150 μm. Note that if the film 20 does not sufficiently follow the shape of the knife edge, the heat dissipation sheet 10 may not be peeled off from the film 20.

[0050] (Width of the film) The width of the film 20 is not particularly limited, but is, for example, 1 to 500 mm.

[0051] (Young's modulus of the film) The Young's modulus of the film is not particularly limited, but is, for example, 1 to 10,000 MPa. Further, from the viewpoint of enabling the film 20 to follow the shape of the knife edge used when peeling the heat dissipation sheet 10 from the film 20, the Young's modulus of the film 20 is preferably 1 to 6,000 MPa, more preferably 100 to 5,000 MPa, and still more preferably 1,000 to 4,500 MPa. The Young's modulus of the film 20 can be measured by the method described in the examples.

[0052] (Unevenness of the film) The film 20 may be provided with unevenness on the main surface 20a of the film on which the heat dissipation sheet 10 is placed. The unevenness may be formed, for example, by embossing. Thereby, the surface adhesion strength of the heat dissipation sheet 10 to the film 20 can be adjusted more accurately. For example, the surface adhesion strength of the heat dissipation sheet 10 to the film 20 can be adjusted by adjusting the depth of the concave portion, the area of the concave portion, etc. of the film 20 formed by embossing. For example, from the viewpoint of setting the surface adhesion strength of the heat dissipation sheet 10 to the film 20 to 1.0 N / mm or less, the depth of the concave portion on the main surface 20a is preferably 5 to 80 μm, more preferably 10 to 70 μm, and still more preferably 20 to 60 μm. Further, from the viewpoint of setting the surface adhesion strength of the heat dissipation sheet 10 to the film 20 to 1.0 N / mm or less, the ratio of the occupied area of the concave portion to the entire area of the film on the main surface 20a of the film 20 is preferably 5 to 95%, more preferably 10 to 90%, and still more preferably 20 to 80%. The depth of the concave portion and the ratio of the occupied area of the concave portion can be measured, for example, by surface shape analysis with a laser microscope.

[0053] (Adhesive layer) In order to adhere the heat dissipation sheet 10, or the heat dissipation sheet 10 and the spacer 30, to the film 20, an adhesive layer (not shown) may be formed on the surface of the film 20. Examples of the adhesive layer include a rubber-based adhesive layer, an acrylic-based adhesive layer, a silicone-based adhesive layer, and a urethane-based adhesive layer. Among these adhesive layers, from the viewpoints of excellent adhesiveness and availability at low cost, an acrylic-based adhesive layer and a rubber-based adhesive layer are preferable, and a rubber-based adhesive layer is more preferable. Examples of the rubber-based adhesive used for the rubber-based adhesive layer include a natural rubber-based adhesive, a styrene-butadiene (SBR)-based adhesive, a recycled rubber-based adhesive, a polyisobutylene rubber-based adhesive, a butyl rubber-based adhesive, and a block copolymer-based adhesive. The thickness of the adhesive layer is, for example, 1 to 200 μm, preferably 5 to 100 μm.

[0054] In addition, when the heat dissipation sheet 10 has adhesiveness, it is not necessary to provide an adhesive layer on the surface of the film 20. Further, when the heat dissipation sheet 10 has strong adhesiveness, a release layer may be provided on the surface of the film 20 so that the heat dissipation sheet 10 can be easily peeled off from the film 20. Further, when the adhesive layer is not provided, in order to weaken the adhesive force between the heat dissipation sheet 10 and the film 20, it is preferable to provide irregularities on the main surface 20a of the film 20 as described above.

[0055] (Usage method of the multilayer structure) The multilayer structure 1 according to an embodiment of the present invention is, for example, unwound from a reel 40, and the heat dissipation sheet 10 placed on the film 20 is picked up by a vacuum nozzle. The unwound film 20 may be folded back at an acute angle in the traveling direction by a knife edge, and it is also preferable that the heat dissipation sheet 10 is peeled off from the film 20 by the folding and the peeled heat dissipation sheet 10 is picked up by a vacuum nozzle. Since the heat dissipation sheet 10 does not have rigidity like a semiconductor device, it is appropriately picked up by being adsorbed by the vacuum nozzle while being peeled off by the knife edge.

[0056] (Manufacturing method of the multilayer structure) The manufacturing method of the multilayer structure 1 according to an embodiment of the present invention is not particularly limited. The multilayer structure 1 can be produced, for example, by providing a spacer on a film having an adhesive layer formed on its surface and then disposing a heat dissipation sheet on the film. Further, the multilayer structure 1 according to an embodiment of the present invention may be produced, for example, as follows. As shown in Fig. 2(a), a heat dissipation composition sheet-shaped molded body 50 of the heat dissipation composition constituting the heat dissipation sheet is attached to a film having an adhesive layer formed on its surface. Next, as shown in Fig. 2(b), the heat dissipation composition sheet-shaped molded body 50 is punched out (half cut) excluding the film so that a portion 51 corresponding to the contour of the heat dissipation sheet is cut. Next, as shown in Fig. 2(c), unnecessary portions of the heat dissipation composition sheet-shaped molded body 50 are removed to form a heat dissipation sheet 10 on the film 20. Then, as shown in Fig. 2(d), a spacer 30 may be attached to a region of the film 20 where unnecessary portions of the heat dissipation composition sheet-shaped molded body have been removed to produce the multilayer structure 1 according to an embodiment of the present invention. In this manufacturing method, the formation of the adhesive layer may be omitted.

[0057] [Modification example of the multilayer structure according to an embodiment of the present invention] The multilayer structure 1 according to an embodiment of the present invention can be modified as follows. (Modification example 1) The spacer 30 of the multilayer structure 1 according to an embodiment of the present invention continuously extended in the length direction on both sides of the heat dissipation sheets 10 arranged in the length direction. However, like the multilayer structure 1A shown in Fig. 3(a), the spacer 30A may continuously extend in the length direction on one side of the heat dissipation sheets 10 arranged in the length direction.

[0058] (Modification example 2) The spacer 30 of the multilayer structure 1 according to an embodiment of the present invention continuously extended in the longitudinal direction on both sides of the heat dissipation sheets 10 arranged in the longitudinal direction. However, like the multilayer structure 1B shown in FIG. 3(b) and the multilayer structure 1C shown in FIG. 3(c), the spacers 30B and 30C may be intermittently arranged along the longitudinal direction on both sides of the heat dissipation sheets 10 arranged in the longitudinal direction. Note that the spacers 30B and 30C may be intermittently arranged along the longitudinal direction on one side of the heat dissipation sheets 10 arranged in the longitudinal direction. However, it is preferable that the spacers 30B and 30C are intermittently arranged along the longitudinal direction on both sides of the heat dissipation sheets 10 arranged in the longitudinal direction.

[0059] (Modification Example 3) The spacer 30 of the multilayer structure 1 according to an embodiment of the present invention continuously extended in the longitudinal direction on both sides of the heat dissipation sheets 10 arranged in the longitudinal direction. However, like the multilayer structure 1D shown in FIG. 4(a), the spacer 30D may be provided in the interval between adjacent heat dissipation sheets 10. In this case, the spacer 30D may extend in the width direction and be provided in each of the intervals between adjacent heat dissipation sheets 10 arranged in the longitudinal direction. Also, like the multilayer structure 1E shown in FIG. 4(b), the spacer 30E does not have to be provided in all the intervals, and may extend in the width direction in the intervals between adjacent heat dissipation sheets 10 and be provided, for example, in every other interval among the intervals arranged in the longitudinal direction. Further, although not shown, the spacer may extend in the width direction in the intervals between adjacent heat dissipation sheets and be provided in every other two or more intervals among the intervals between adjacent heat dissipation sheets 10 arranged in the longitudinal direction.

[0060] (Modification Example 4) The spacer 30 of the multilayer structure 1 according to one embodiment of the present invention continuously extended in the longitudinal direction on both sides of the heat dissipation sheets 10 arranged in the longitudinal direction. However, like the multilayer structure 1F shown in FIG. 5, the spacer 30F may surround each heat dissipation sheet 10. In this case, by arranging the spacer 30F on the film prior to the heat dissipation sheet 10 during the manufacture of the multilayer structure, alignment of the heat dissipation sheet 10 becomes easy, and the heat dissipation sheet 10 can be arranged at a predetermined position with little error. Therefore, it becomes possible to surely perform picking up of the heat dissipation sheet 10 and the like.

[0061] (Modification 5) The spacer 30 of the multilayer structure 1 according to one embodiment of the present invention was placed on the first main surface 20a of the film 20. However, the spacer may be in another form as long as it can be arranged so as to be aligned with the heat dissipation sheet on the first main surface 20a of the film 20. For example, as shown in FIG. 6, the spacer 30G may be placed on the second main surface 20b of the film 20. In this case, when the film 20 is wound up in a roll shape, the spacer 30G is arranged so as to be aligned with the heat dissipation sheet 10 on the first main surface 20a of the film 20. And the spacer 30G can regulate the heat dissipation sheet 10 placed on the first main surface 20a of the film 20 from contacting the film 20 itself (that is, the second main surface 20b of the film).

[0062] (Modification 6) The multilayer structure 1 according to one embodiment of the present invention was in the form of taping. However, the form of the multilayer structure according to one embodiment of the present invention is not particularly limited as long as it is a form of a multilayer structure including a heat dissipation sheet, a film, and a spacer. For example, like the multilayer structure 1H shown in FIG. 7, it may be in the form of a tray in which the heat dissipation sheets 10 are arranged in the vertical and horizontal directions. In this case, spacers may be provided on another multilayer structure (sheet member). For example, spacers 30H may be provided on the main surface 20b opposite to the main surface on which the heat dissipation sheet 10 of another multilayer structure 1H is provided. According to such a configuration, when the multilayer structure 1H is stacked on another multilayer structure 1H, the spacer 30H can regulate the contact between the heat dissipation sheet 10 and the film 20H of the other multilayer structure 1H.

[0063] The multilayer structure according to an embodiment of the present invention and Modifications 1 to 6 of the multilayer structure according to an embodiment of the present invention can be arbitrarily combined. From the viewpoint of stability when unwinding from a reel, it is preferable to arrange spacers on both sides of each of the heat dissipation sheets 10 and sandwich the heat dissipation sheet 10 with the spacers arranged on both sides. That is, compared with the mode in which the heat dissipation sheet 10 is not sandwiched by the spacers as shown in FIGS. 3(a) and 3(c), or the mode in which a plurality of heat dissipation sheets 10 are sandwiched by the spacers as shown in FIG. 4(b), as shown in FIGS. 2(d), 4(a), 5, and 3(b), by arranging each heat dissipation sheet 10 to be sandwiched by the spacers, it becomes easier to ensure the stability when unwinding from the reel.

[0064] The multilayer structure according to an embodiment of the present invention and Modifications 1 to 6 of the multilayer structure according to an embodiment of the present invention are merely examples of the multilayer structure of the present invention. Therefore, the multilayer structure of the present invention is not limited to the multilayer structure according to an embodiment of the present invention and Modifications 1 to 6 of the multilayer structure according to an embodiment of the present invention.

Example

[0065] Examples of the present invention will be described below. However, the present invention is not limited to the examples.

[0066] (Example 1) (Fabrication of heat dissipation sheet) 100 parts by mass of hydrogenated polybutadiene rubber (trade name "L-1203", manufactured by Kuraray Co., Ltd., liquid), 340 parts by mass of boron nitride (manufactured by Denka Co., Ltd., trade name "SGP", plate-like (scaly), average particle diameter 18 μm, aspect ratio 81) were melt-kneaded, and then extruded with an extruder for manufacturing a multilayer molding block. A multilayer molding block with a thickness of 1,000 μm per layer (width of the heat-conductive resin layer is 1,000 μm) and 10 layers laminated was obtained. The multilayer molding block was sliced so that the plane perpendicular to the laminated surface became the sheet surface, and a heat dissipation sheet having a thickness of 1,000 μm was obtained. The obtained heat dissipation sheet was irradiated with an electron beam of an acceleration voltage of 750 kV at 150 kGy, and further irradiated with an electron beam of an acceleration voltage of 300 kV at 600 kGy to obtain a heat dissipation sheet.

[0067] (Fabrication of Multilayer Structure) A raw roll of film (polyethylene terephthalate, trade name "Lumirror #100-S10", manufactured by Toray Industries, Inc., thickness: 100 μm, Young's modulus: 4,100 MPa) was prepared. Using a slitter, the raw roll was cut into a width of 100 mm to produce a long tape-like film. A rubber-based adhesive (trade name "Olivine BPS5079-1", manufactured by Toyochem Co., Ltd.) was applied to the surface of this tape-like film and dried at a temperature of 100 °C to produce a film having an adhesive layer with a thickness of 10 μm on the surface.

[0068] The heat dissipation sheet was attached to the entire surface of this film. Next, using a die cutter, the film with the heat dissipation sheet attached was half-cut into a size of 2.0 mm × 2.0 mm. Then, the unnecessary portion of the heat dissipation sheet was peeled off from the film to produce a film having a plurality of heat dissipation sheets with a size of 2.0 mm × 2.0 mm arranged in the length direction on the surface.

[0069] A raw roll of foam (polyolefin-based foam, trade name "WL10", manufactured by Sekisui Chemical Co., Ltd., thickness: 1,050 μm, 25% compressive strength: 50 kPa) was prepared. Using a slitter, the raw roll was cut into a width of 100 mm to produce a tape-shaped foam. At intervals between adjacent heat dissipation sheets arranged in the length direction of the film, the tape-shaped foam was attached so as to extend in the width direction within each interval. Then, the heat dissipation sheet and the film with the long tape-shaped foam attached were passed through a pressure roller having a linear pressure of 30 kPa and wound onto a reel to produce the multilayer structure of Example 1. As the planar shape of the multilayer structure, the opening shape determined by the arrangement relationship of the spacers with respect to the heat dissipation sheet was as shown in Fig. 4(a).

[0070] (Example 2) Instead of the raw roll of polyolefin-based foam, a raw roll of foam (polyurethane-based foam, trade name "H-32", manufactured by Rogers Inoaak Co., Ltd., thickness: 1,500 μm, 25% compressive strength: 140 kPa) was used. Otherwise, the multilayer structure of Example 2 was produced in the same manner as the multilayer structure of Example 1.

[0071] (Example 3) Instead of the raw roll of polyolefin-based foam, a raw roll of foam (polyurethane-based foam, trade name "H-32", manufactured by Rogers Inoaak Co., Ltd., thickness: 2,500 μm, 25% compressive strength: 140 kPa) was used. Otherwise, the multilayer structure of Example 2 was produced in the same manner as the multilayer structure of Example 1.

[0072] (Example 4) (Production of heat dissipation sheet) A heat dissipation sheet was produced in the same manner as the above heat dissipation sheet, except that the thickness of the heat dissipation sheet was changed from 1,000 μm to 2,000 μm.

[0073] (Production of multilayer structure) A heat dissipation sheet with a thickness changed from 1,000 μm to 2,000 μm was used, and instead of the raw roll of polyolefin foam, a raw roll of foam (polyurethane foam, trade name "L-24", manufactured by Rogers Inoaak Co., Ltd., thickness: 2,100 μm, 25% compression strength: 40 kPa) was used. Otherwise, the multilayer structure of Example 4 was produced in the same manner as the multilayer structure of Example 1.

[0074] (Example 5) A heat dissipation sheet manufactured in the same manner as in Example 4 was used, and instead of the raw roll of polyolefin foam, a raw roll of foam (polyurethane foam, trade name "H-48", manufactured by Rogers Inoaak Co., Ltd., thickness: 2,100 μm, 25% compression strength: 250 kPa) was used. Otherwise, the multilayer structure of Example 5 was produced in the same manner as the multilayer structure of Example 1.

[0075] (Example 6) Instead of the raw roll of polyolefin foam, a raw roll of foam (polyurethane foam, trade name "H-32", manufactured by Rogers Inoaak Co., Ltd., thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. Otherwise, the multilayer structure of Example 6 was produced in the same manner as the multilayer structure of Example 1.

[0076] (Example 7) Instead of the raw roll of polyolefin foam, a raw roll of foam (polyurethane foam, trade name "H-32", manufactured by Rogers Inoaak Co., Ltd., thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. And the attachment position of the tape-shaped foam on the film was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet became as shown in Fig. 2(d) as the planar shape of the multilayer structure. Otherwise, the multilayer structure of Example 7 was produced in the same manner as the multilayer structure of Example 1.

[0077] (Example 8) Instead of using a roll of the polyolefin-based foam stock, a roll of foam stock (a polyurethane-based foam, product name "H-32", manufactured by Rogers Corporation, thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. And the position where the tape-shaped foam is attached to the film, as the planar shape of the multilayer structure, was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet is as shown in Fig. 5. Otherwise, the multilayer structure of Example 8 was produced in the same manner as the multilayer structure of Example 1.

[0078] (Example 9) Instead of using a roll of the polyolefin-based foam stock, a roll of foam stock (a polyurethane-based foam, product name "H-32", manufactured by Rogers Corporation, thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. And the position where the tape-shaped foam is attached to the film, as the planar shape of the multilayer structure, was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet is as shown in Fig. 3(b). Otherwise, the multilayer structure of Example 8 was produced in the same manner as the multilayer structure of Example 1.

[0079] (Example 10) Instead of using a roll of the polyolefin-based foam stock, a roll of foam stock (a polyurethane-based foam, product name "H-32", manufactured by Rogers Corporation, thickness: 3,000 μm, 25% compression strength: 140 kPa) was used. Otherwise, the multilayer structure of Example 10 was produced in the same manner as the multilayer structure of Example 1.

[0080] (Example 11) Using a heat dissipation sheet manufactured in the same manner as in Example 4, instead of using a roll of the polyolefin-based foam stock, a roll of foam stock (a polyurethane-based foam, product name "HH-48", manufactured by Rogers Corporation, thickness: 2,100 μm, 25% compression strength: 390 kPa) was used. Otherwise, the multilayer structure of Example 11 was produced in the same manner as the multilayer structure of Example 1.

[0081] (Example 12) Instead of using a roll of polyolefin foam stock, a roll of foam stock (a polyurethane foam, product name "H-32", manufactured by Rogers Enochac Co., Ltd., thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. Then, the position where the tape-shaped foam is attached to the film, as the planar shape of the multilayer structure, was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet is as shown in Fig. 3(a). Otherwise, the multilayer structure of Example 12 was produced in the same manner as the multilayer structure of Example 1.

[0082] (Example 13) Instead of using a roll of polyolefin foam stock, a roll of foam stock (a polyurethane foam, product name "H-32", manufactured by Rogers Enochac Co., Ltd., thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. Then, the position where the tape-shaped foam is attached to the film, as the planar shape of the multilayer structure, was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet is as shown in Fig. 4(b). Otherwise, the multilayer structure of Example 13 was produced in the same manner as the multilayer structure of Example 1.

[0083] (Example 14) Instead of using a roll of polyolefin foam stock, a roll of foam stock (a polyurethane foam, product name "H-32", manufactured by Rogers Enochac Co., Ltd., thickness: 1,500 μm, 25% compression strength: 140 kPa) was used. Then, the position where the tape-shaped foam is attached to the film, as the planar shape of the multilayer structure, was changed so that the opening shape determined by the relationship of the arrangement of the spacers with respect to the heat dissipation sheet is as shown in Fig. 3(c). Otherwise, the multilayer structure of Example 14 was produced in the same manner as the multilayer structure of Example 1.

[0084] (Comparative Example 1) A raw roll of foam (polyolefin-based foam, trade name "WL10", manufactured by Sekisui Chemical Co., Ltd., thickness: 1,020 μm, 25% compression strength: 50 kPa) was used. By reducing the thickness of the spacer, the spacer could no longer regulate the contact between the sheet member disposed on the heat dissipation sheet and the heat dissipation sheet. Otherwise, a multilayer structure of Comparative Example 1 was produced in the same manner as the multilayer structure of Example 1.

[0085] (Comparative Example 2) Using a heat dissipation sheet manufactured in the same manner as in Example 4, a raw roll of foam (polyurethane-based foam, trade name "LE-20", manufactured by Rogers Inoaak Co., Ltd., thickness: 2,100 μm, 25% compression strength: 20 kPa) was used instead of the raw roll of polyolefin-based foam. By changing the material of the spacer, the spacer could no longer regulate the contact between the sheet member disposed on the heat dissipation sheet and the heat dissipation sheet. Otherwise, a multilayer structure of Comparative Example 2 was produced in the same manner as the multilayer structure of Example 1.

[0086] (Evaluation of Heat Dissipation Sheet) (1) Measurement of the Orientation Angle of Thermally Conductive Particles The cross-section of the heat dissipation sheet was observed with a scanning electron microscope (S-4700 manufactured by Hitachi, Ltd.). From the observation image at a magnification of 3000 times, for any 20 thermally conductive particles, the angle formed with the sheet surface was measured, and the average value was taken as the orientation angle.

[0087] (2) Measurement of Thermal Conductivity A 25 mm square heat dissipation sheet was sandwiched between a ceramic heater and a water-cooled heat dissipation plate and heated. After 20 minutes had passed, the temperature T1 of the ceramic heater and the temperature T2 of the water-cooled heat dissipation plate were measured, and the applied power W of the ceramic heater, the thickness t of the heat dissipation sheet, and the area S of the heat dissipation sheet were substituted into the following formula to calculate the thermal conductivity λ. λ = t × W / {S × (T1 - T2)} (3) 30% Compression Strength The 30% compression strength of the obtained heat dissipation sheet was measured using "RTG-1250" manufactured by A&D Company. The sample dimensions were adjusted to 2 mm × 15 mm × 15 mm, the measurement temperature was 23°C, and the compression rate was 1 mm / min for the measurement. (4) Tensile strength The tensile strength of the obtained heat dissipation sheet was measured using "RTG-1250" manufactured by A&D Company. The sample dimensions were 1.5 mm × 10 mm × 60 mm, the measurement temperature was 23°C, and the tensile rate was 500 mm / min for the measurement. (5) Asker C hardness The heat dissipation sheets with a size of 25 mm square were laminated so that the thickness was 10 mm or more, and measured at 23°C using an Asker rubber hardness tester type C (manufactured by Kobunshi Keiki Co., Ltd.). (6) Surface adhesion strength The surface adhesion strength of the heat dissipation sheet was measured according to the following (i) to (iii). (i) A T-shaped aluminum jig (A5052) 213 consisting of a polycarbonate plate 211 with a thickness of 10 mm and a size of 50 mm × 50 mm, a flat plate portion 213a (size 25 mm × 25 mm), and a plate-like member 213b (length 25 mm) fixed vertically upward from the center of the flat plate portion 213a was prepared (see Fig. 8). Furthermore, a double-sided adhesive tape 212 (product name "Double Tack Tape No. 570E", manufactured by Sekisui Chemical Co., Ltd.), and a sample of the heat dissipation sheet 10 temporarily adhered on the film 20 were prepared (see Fig. 8). (ii) As shown in Fig. 8, the heat dissipation sheet 10 and the film 20 were respectively attached to the polycarbonate plate 211 and the flat plate portion 213a of the T-shaped aluminum jig 213 using the double-sided adhesive tape 212. (iii) After curing at 23°C for 1 hour in the state of (ii) above, the polycarbonate plate was fixed to a tensile testing machine (manufactured by A&D, tensilon RTG-1310), the T-shaped aluminum jig 13 was pulled upward at 1.0 mm / min, and the stress (N / mm 2It was measured. The measurement was performed under the conditions of a chuck distance of 0.17 mm and a gauge distance of 0.17 mm. If peeling occurred at locations other than the above, such as the interface of the double-sided adhesive tape 212, a double-sided adhesive tape with stronger adhesive strength was used. And in this measurement, the maximum value of the stress was defined as the "surface adhesion strength".

[0088] (Evaluation of the spacer) (1) 25% Compressive strength The 25% compressive strength of the obtained spacer was measured using "RTG-1250" manufactured by A&D Company. The sample dimensions were adjusted to 2 mm × 15 mm × 15 mm, and the measurement was carried out at a measurement temperature of 23°C and a compression rate of 1 mm / min. (2) Opening shape The opening shape is the planar shape of the location on the heat dissipation sheet where the spacer is not arranged, and the relationship between the arrangement of the spacer with respect to the heat dissipation sheet was classified as follows. Opening shape A: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 4(a). Opening shape B: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 2(d). Opening shape C: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 5. Opening shape D: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 3(b). Opening shape E: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 3(a). Opening shape F: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 4(b). Opening shape G: The relationship between the arrangement of the spacer with respect to the heat dissipation sheet is the shape shown in Fig. 3(c).

[0089] (Evaluation of the film) (1) Young's modulus In an atmosphere of 23°C, a film with a width of 25 mm was pulled using "RTG-1250" manufactured by A&D Company under the conditions of a tensile speed of 300 mm / min and a chuck interval of 100 mm, and the Young's modulus (tensile elastic modulus) was obtained from the tangent of the rising part of the stress of its S-S curve.

[0090] (Evaluation of Multilayer Structure) (1) Transfer Evaluation on the Back of the Film The film was unwound from the reel, and it was checked whether the heat dissipation sheet was attached to the back of the film. A: No heat dissipation sheet was attached to the back of the film. B: There was a heat dissipation sheet attached to the back of the film. (2) Winding Defect Evaluation It was checked whether the film was wound onto the reel without winding defects. A: No winding defect. B: There was a winding defect. (3) Conveyance Stability When the film was unwound from the reel using a feeder for film carrier parts (manufactured by Mitsui Kinzoku Kiso Kogyo Co., Ltd.), it was checked whether it could be unwound stably. A: The unwinding of the film was stable. B: The unwinding of the film was unstable. (4) Film Peeling Evaluation at the Knife Edge Using a feeder for film carrier parts (manufactured by Mitsui Kinzoku Kiso Kogyo Co., Ltd.), it was checked whether the heat dissipation sheet was peeled off from the film at the knife edge part. A: All heat dissipation sheets were peeled off from the film. B: There was a heat dissipation sheet that was not peeled off from the film. (5) Pick-up Evaluation Using a feeder for film carrier parts (manufactured by Mitsui Kinzoku Kiso Kogyo Co., Ltd.), it was checked whether the heat dissipation sheet could be picked up from the film using a suction nozzle. A: The heat dissipation sheet could be picked up. B: The heat dissipation sheet could not be picked up. (6) Presence or Absence of Scratches on the Surface after Picking up the Heat Dissipation Sheet Using a feeder for film carrier parts (manufactured by Mitsui Kinzoku Kiso Kogyo Co., Ltd.), the presence or absence of scratches on the surface of the heat dissipation sheet after picking up using a suction nozzle was visually checked. A: There were no scratches on the surface of the heat dissipation sheet. B: There was a scratch on the surface of the heat dissipation sheet. (7) Presence or absence of deformation of the heat dissipation sheet after pickup. Using a feeder for film carrier parts (manufactured by Mitsui Kinzoku Kiso Kogyo Co., Ltd.), the presence or absence of deformation of the heat dissipation sheet after pickup using a suction nozzle was examined. A: There was no deformation of the heat dissipation sheet. B: There was deformation of the heat dissipation sheet. (8) Comprehensive evaluation A: The transfer evaluation was A, and all other evaluations were also A. B: The transfer evaluation was A, and at least one of the other evaluations was B. C: The transfer evaluation was B.

[0091]

Table 1

[0092]

Table 2

[0093]

Table 3

[0094] From the above examples and comparative examples, it was found that by providing the multilayer structure with a spacer that regulates the contact between the sheet member disposed on the heat dissipation sheet and the heat dissipation sheet, it is possible to suppress the adhesion of the heat dissipation sheet to the sheet member.

Explanation of reference signs

[0095] 1, 1A~1H Multilayer structure 10 Heat dissipation sheet 20, 20H Film (sheet member) 30, 30A~30H Spacer 40 Reel 50 Heat dissipation composition sheet-shaped molded body 211 Polycarbonate plate 212 Double-sided adhesive tape 213 T-shaped aluminum jig

Claims

1. A multilayer structure comprising a film, a heat dissipation sheet placed on one main surface of the film and containing heat conduction particles and a resin, and a spacer arranged on the one main surface of the film so as to be aligned with the heat dissipation sheet, wherein the spacer restricts contact between a sheet member disposed on the heat dissipation sheet and the heat dissipation sheet, the difference (d1 - d2) between the thickness (d1) of the spacer and the thickness (d2) of the heat dissipation sheet is 25 μm or more, and the 25% compressive strength of the spacer is 30 kPa or more.

2. The multilayer structure according to claim 1, wherein the multilayer structure is wound into a roll shape, and the spacer restricts contact between the main surface of the film opposite to the one main surface of the film and the heat dissipation sheet.

3. The multilayer structure according to claim 1 or 2, wherein the spacer is placed on the one main surface of the film.

4. The multilayer structure according to any one of claims 1 to 3, wherein the difference (d1 - d2) between the thickness (d1) of the spacer and the thickness (d2) of the heat dissipation sheet is 1750 μm or less.

5. The multilayer structure according to any one of claims 1 to 4, wherein the 25% compressive strength of the spacer is 300 kPa or less.

6. The film is a long tape-shaped film having a length direction and a width direction, a plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval, and the spacer is provided continuously or intermittently in the length direction on one side or both sides of the heat dissipation sheets arranged in the length direction. The multilayer structure according to any one of claims 1 to 5.

7. The film is a long tape-shaped film having a length direction and a width direction, a plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval, and the spacer surrounds each of the heat dissipation sheets. The multilayer structure according to any one of claims 1 to 5.

8. The film is a long tape-shaped film having a length direction and a width direction, a plurality of the heat dissipation sheets are arranged in the length direction at a predetermined interval, and the spacer is provided in the interval between adjacent heat dissipation sheets. The multilayer structure according to any one of claims 1 to 5.

9. The multilayer structure according to any one of claims 1 to 8, wherein the spacer is a foam.

10. The multilayer structure according to claim 9, wherein the foam is a polyolefin-based resin foam or a polyurethane-based resin foam.

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