Thermally conductive adhesive sheet

Abstract

Provided is a thermally conductive adhesive sheet having excellent peel strength.　One embodiment of the present invention is a thermally conductive adhesive sheet comprising a thermally conductive sheet layer and an adhesive layer provided on at least one main surface of the thermally conductive sheet layer. The adhesive layer includes an adhesive agent layer formed by an adhesive agent. The thermally conductive adhesive sheet satisfies at least either condition (i) or condition (ii). (i) [The elastic modulus of the adhesive agent layer at 25°C] > [the elastic modulus of the thermally conductive sheet layer at 25°C] (ii) [The elastic modulus of the adhesive agent layer at 80°C] > [the elastic modulus of the thermally conductive sheet layer at 80°C]

Description

Thermally conductive adhesive sheet

[0001] The present invention relates to a thermally conductive adhesive sheet.

[0002] Conventionally, a technique has been developed for further improving heat dissipation by interposing a thermally conductive adhesive sheet between a heat-generating member and a heat-dissipating member.

[0003] For example, Patent Document 1 discloses a thermally conductive sheet for electronic devices, which includes a foam sheet and an adhesive material provided on at least one surface of the foam sheet.

[0004] JP 2017-79264 A

[0005] However, when a thermally conductive sheet according to the prior art is attached to a heat dissipation member or the like, it is prone to peeling off due to an external impact.

[0006] Therefore, an object of the present invention is to provide a thermally conductive adhesive sheet that has excellent peel strength.

[0007] The present inventors have conducted extensive research and found that the above-mentioned problems can be solved by a thermally conductive adhesive sheet that combines a specific thermally conductive sheet layer and an adhesive layer.

[0008] One aspect of the present invention is a thermally conductive adhesive sheet comprising a thermally conductive sheet layer and an adhesive layer provided on at least one main surface of the thermally conductive sheet layer, the adhesive layer including an adhesive layer formed from an adhesive, and satisfying at least one of the following conditions (i) and (ii): (i) [Modulus of elasticity of the adhesive layer at 25°C] > [Modulus of elasticity of the thermally conductive sheet layer at 25°C], and (ii) [Modulus of elasticity of the adhesive layer at 80°C] > [Modulus of elasticity of the thermally conductive sheet layer at 80°C].

[0009] The thermally conductive sheet layer preferably has a modulus of elasticity at 25° C. of 10.0 MPa to 500.0 MPa.

[0010] The shear strength measured under the following measurement conditions is preferably 0.5 MPa or more. (Measurement Conditions) Shear strength is measured using a universal tensile tester. A thermally conductive adhesive sheet (20 mm wide x 20 mm long) is sandwiched on both sides between a stainless steel plate (30 mm wide x 30 mm long x 1 mm thick) and an alumina plate (20 mm wide x 20 mm long x 1 mm thick), and heated and pressed at 120°C and a pressure of 1.0 MPa for 15 minutes to prepare a test specimen. One end of the stainless steel plate is gripped with the lower chuck of the universal tensile tester (RTF-1310 manufactured by A&D Co., Ltd.), and the end face of the test specimen facing the lower chuck is pressed with a stainless steel jig at a test speed of 2 mm / min. The shear strength is the maximum load value at which the test specimen breaks. The ratio of the thickness of the adhesive layer to the thickness of the thermally conductive sheet layer (thickness of the adhesive layer / thickness of the thermally conductive sheet layer) is preferably 0.05 to 0.50. The adhesive layer is preferably provided on both main surfaces of the thermally conductive sheet layer. The thermal conductivity of the thermally conductive adhesive sheet is preferably 0.4 W / (m·K) to 10 W / (m·K). The breakdown voltage of the thermally conductive adhesive sheet is preferably 600 V or higher. The adhesive layer preferably comprises a support layer and the adhesive layer is provided on both main surfaces of the support layer. The following condition (iii) is preferably satisfied: (iii) [Elastic modulus of the support layer at 25°C]>[Elastic modulus of the adhesive layer at 25°C] The ratio of the elastic modulus of the support layer at 25°C to the elastic modulus of the adhesive layer at 25°C (elastic modulus of the support layer / elastic modulus of the adhesive layer) is preferably greater than 2 and less than 100. The thickness of the support layer is preferably 5 μm to 50 μm. The thickness of the adhesive layer is preferably 1 μm to 20 μm.

[0011] Another aspect of the present invention is a member for semiconductor manufacturing equipment, comprising the thermally conductive adhesive sheet.

[0012] According to the present invention, a thermally conductive adhesive sheet having excellent peel strength is provided.

[0013] Figure 1 shows a conceptual side view of a double-sided thermally conductive adhesive sheet, Figure 2 shows a conceptual side view of a single-sided thermally conductive adhesive sheet, and Figure 3 shows a conceptual side view of an adhesive layer.

[0014] In this specification, when an upper limit value and a lower limit value are separately described, it is considered that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0015] In this specification, unless otherwise specified, various measurements are carried out at room temperature (25° C.).

[0016] The structure, physical properties / characteristics, production method, and uses of the thermally conductive adhesive sheet will be described below, but the present invention is not limited thereto.

[0017] 1 and 2 show conceptual side views of a thermally conductive adhesive sheet according to the present disclosure. The thermally conductive adhesive sheet comprises a thermally conductive sheet layer and an adhesive layer provided on at least one main surface of the thermally conductive sheet layer. Furthermore, as will be described later, the adhesive layer includes at least an adhesive layer (a layer formed from an adhesive).

[0018] The thermally conductive adhesive sheet may be a double-sided adhesive type in which adhesive layers are provided on both main surfaces of the thermally conductive sheet layer, as shown in Fig. 1, or a single-sided adhesive type in which an adhesive layer is provided on only one main surface of the thermally conductive sheet layer, as shown in Fig. 2. The thermally conductive adhesive sheet is preferably a double-sided adhesive type as shown in Fig. 1. When the thermally conductive adhesive sheet is a single-sided type, a layer other than the thermally conductive sheet layer may be provided on the surface of the thermally conductive adhesive sheet other than the surface on which the adhesive layer is provided.

[0019] The thermally conductive sheet layer and adhesive layer constituting the thermally conductive adhesive sheet preferably satisfy at least one of the following conditions (i) and (ii), and more preferably satisfy both of the following conditions (i) and (ii): (i) [Modulus of elasticity of adhesive layer at 25°C]>[Modulus of elasticity of thermally conductive sheet layer at 25°C] (ii) [Modulus of elasticity of adhesive layer at 80°C]>[Modulus of elasticity of thermally conductive sheet layer at 80°C]

[0020] More specifically, the ratio of the elastic modulus of the adhesive layer at 25°C to the elastic modulus of the thermally conductive sheet layer at 25°C (elastic modulus of adhesive layer / elastic modulus of thermally conductive sheet layer) is preferably greater than 1.0 and less than 50.0, more preferably greater than 1.0 and less than 30.0, even more preferably greater than 1.0 and less than 10.0, and particularly preferably greater than 1.0 and less than 5.0.

[0021] Furthermore, the ratio of the elastic modulus of the adhesive layer at 80°C to the elastic modulus of the thermally conductive sheet layer at 80°C (elastic modulus of adhesive layer / elastic modulus of thermally conductive sheet layer) is preferably greater than 1.0 and not greater than 100.0, more preferably greater than 1.0 and not greater than 50.0, even more preferably greater than 1.0 and not greater than 20.0, and particularly preferably greater than 1.0 and not greater than 10.0.

[0022] Because the elastic modulus of the thermally conductive sheet layer and the elastic modulus of the adhesive layer are in this relationship, when the thermally conductive adhesive sheet is attached to an adherend (a heat-generating body or a heat-dissipating body), the adhesion (following ability) to the adherend and impact absorption are improved, which makes it easier to improve shear strength.

[0023] In the case of a double-sided adhesive type in which adhesive layers are provided on both main surfaces of the thermally conductive sheet layer, when it is stated that "the thermally conductive adhesive sheet satisfies at least one of condition (i) and condition (ii)," only one combination of adhesive layer and thermally conductive sheet layer may satisfy at least one of condition (i) and condition (ii), but it is preferable that both combinations of adhesive layer and thermally conductive sheet layer satisfy at least one of condition (i) and condition (ii).

[0024] Here, the elastic modulus of the thermally conductive sheet layer, adhesive layer, thermally conductive adhesive sheet, and support layer is measured according to the following method. (Measurement Method) The elastic modulus is measured using a universal tensile tester. A test specimen measuring 25 mm wide x 150 mm long is prepared. The distance between the upper and lower chucks of the universal tensile tester (RTF-1310 manufactured by A&D Co., Ltd.) is set to 100 mm, and both ends of the test specimen are gripped so that the length of the test specimen is the same as the distance between the chucks. A tensile test is performed at a test speed of 1 mm / min, and the obtained value is taken as the elastic modulus. For each test specimen, the elastic modulus is measured at two points: in one measurement direction and in a measurement direction perpendicular to the measurement direction, and the average value is taken as the elastic modulus.

[0025] The total thickness of the thermally conductive adhesive sheet varies depending on the thickness of the thermally conductive sheet layer, the thickness of the adhesive layer, and the number of layers stacked, and is not particularly limited. The total thickness of the thermally conductive adhesive sheet is, for example, 10 μm to 2000 μm, 10 μm to 1000 μm, or 50 μm to 800 μm. More specifically, the total thickness of the thermally conductive adhesive sheet is preferably 100 μm to 700 μm, more preferably 100 μm to 600 μm, and even more preferably 150 μm to 300 μm.

[0026] Next, the thermally conductive sheet layer and adhesive layer that constitute the thermally conductive adhesive sheet will be described.

[0027] <<Thermal Conductive Sheet Layer>> The thermal conductive sheet layer is a layer formed from a thermal conductive sheet.

[0028] The thermally conductive sheet layer is generally made of a sheet-like member containing a polymer material and a thermally conductive material dispersed in the polymer material.

[0029] The thermal conductivity of the thermally conductive sheet layer is not particularly limited and can be adjusted appropriately depending on the application. For example, the thermally conductive sheet layer may have a thermal conductivity of 1.0 W / (m·K) or more.

[0030] Examples of polymer materials that can constitute the thermally conductive sheet layer include resin materials such as acrylic resin, polyamide resin, polyimide resin, polyester resin, polyolefin resin, polyurethane resin, epoxy resin, and silicone resin; and elastomers such as rubber-based elastomers (fluororubber, silicone rubber, etc.).

[0031] Examples of thermally conductive materials that can form the thermally conductive sheet layer include metal materials such as copper, aluminum, gold, and silver; resin materials coated with these metal materials; carbon materials such as carbon fiber, CNT, graphene, graphite, and carbon black; metal oxides such as silicon oxide (silica), aluminum oxide (alumina), and magnesium oxide; metal nitrides such as silicon nitride, aluminum nitride, and boron nitride; metal carbides such as silicon carbide; and metal hydroxides such as magnesium hydroxide. Two or more types of thermally conductive materials may be combined. For example, examples of thermally conductive materials include those containing carbon fiber and a thermally conductive material other than carbon fiber (thermally conductive filler, thermally conductive fiber).

[0032] The elastic modulus of the thermally conductive sheet layer at 25°C is not particularly limited, but is preferably 5.0 MPa or more, 10.0 MPa or more, 20.0 MPa or more, or 50.0 MPa or more, and is preferably 500.0 MPa or less, 200.0 MPa or less, 150.0 MPa or less, or 100.0 MPa or less. More specifically, the elastic modulus of the thermally conductive sheet layer at 25°C is preferably 10.0 MPa to 200.0 MPa, more preferably 20 to 150.0 MPa, and even more preferably 50 MPa to 150.0 MPa.

[0033] The elastic modulus of the thermally conductive sheet layer at 80°C is not particularly limited, but is preferably 1.0 MPa or more, 2.0 MPa or more, 5.0 MPa or more, or 10.0 MPa or more, and is preferably 400.0 MPa or less, 200.0 MPa or less, 150.0 MPa or less, or 100.0 MPa or less. More specifically, the elastic modulus of the thermally conductive sheet layer at 80°C is preferably 2.0 MPa to 200.0 MPa, more preferably 5.0 to 150.0 MPa, and even more preferably 10.0 MPa to 150.0 MPa.

[0034] The elastic modulus of the thermally conductive sheet layer can be adjusted by changing the type of resin material or the ratio of the resin material to the thermally conductive material. It is also possible to adjust the elastic modulus of the thermally conductive sheet layer by adjusting the orientation of the thermally conductive material in the thermally conductive sheet layer or by localizing the thermally conductive material in the thermally conductive sheet layer.

[0035] As described above, the thermally conductive sheet layer preferably satisfies the following conditions: [Modulus of elasticity of adhesive layer at 25°C] > [Modulus of elasticity of thermally conductive sheet layer at 25°C] and / or [Modulus of elasticity of adhesive layer at 80°C] > [Modulus of elasticity of thermally conductive sheet layer at 80°C]. In other words, the thermally conductive sheet layer is preferably configured to have a lower modulus of elasticity than the adhesive layer. One form of a thermally conductive sheet layer with such a low modulus of elasticity is a sheet-like member obtained by slicing (by cutting the fibers) a block of resin containing fibrous thermally conductive material. This sheet-like member has a structure in which the fiber axis of the thermally conductive material is aligned perpendicular to the sheet surface, thereby reducing the modulus of elasticity. Examples of such sheet-like members include those disclosed in, for example, Japanese Patent Application Laid-Open No. 2022-119196. Another form of a thermally conductive sheet layer with such a low modulus of elasticity is a sheet-like member obtained by slicing a laminate of multiple sheets containing fibrous thermally conductive material oriented in the resin. As such a sheet-like member, those disclosed in JP 2018-127530 A, JP 2021-158274 A, etc. can be used.

[0036] The thickness of the thermally conductive sheet layer is not particularly limited, but is preferably 10 μm to 1000 μm, 50 μm to 800 μm, or 100 μm to 600 μm. From the viewpoint of achieving a good balance between thermal conductivity and adhesiveness, the thickness of the thermally conductive sheet layer is preferably 50 μm to 800 μm, more preferably 100 μm to 600 μm, and even more preferably 100 μm to 300 μm.

[0037] The thermally conductive sheet layer may contain other components, such as dispersants, curing agents, tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, and colorants.

[0038] <<Adhesive Layer>> Fig. 3 shows a conceptual side view of the adhesive layer. The adhesive layer includes an adhesive layer. The adhesive layer may be, for example, (Configuration 1) a double-sided tape type having a support layer and adhesive layers provided on both main surfaces of the support layer as shown in Fig. 3, or (Configuration 2) a substrateless type formed only by an adhesive layer. From the viewpoint of improving insulation properties, the adhesive layer is preferably a double-sided tape type.

[0039] The elastic modulus of the adhesive layer at 25° C. is not particularly limited, but is preferably 10.0 MPa or more, 20.0 MPa or more, or 50.0 MPa or more, and is preferably 500.0 MPa or less, 200.0 MPa or less, or 100.0 MPa or less. More specifically, the elastic modulus of the adhesive layer at 25° C. is preferably 10.0 MPa or more and 500.0 MPa or less, more preferably 20.0 MPa or more and 200.0 MPa or less, and even more preferably 50.0 MPa or more and 100.0 MPa or less.

[0040] The elastic modulus of the adhesive layer at 80°C is not particularly limited, but is preferably 10.0 MPa or more, 20.0 MPa or more, or 50.0 MPa or more, and is preferably 500.0 MPa or less, 200.0 MPa or less, or 100.0 MPa or less. More specifically, the elastic modulus of the adhesive layer at 80°C is preferably 10.0 MPa or more and 500.0 MPa or less, more preferably 20.0 MPa or more and 200.0 MPa or less, and even more preferably 50.0 MPa or more and 100.0 MPa or less.

[0041] The thickness of the adhesive layer varies depending on the layer structure of the adhesive layer and is not particularly limited. The thickness of the adhesive layer is, for example, preferably 1 μm to 200 μm, more preferably 1 μm to 100 μm, even more preferably 1 μm to 50 μm, and even more preferably 1 μm to 25 μm. By setting the thickness to such a range, the thermal conductivity is likely to be improved.

[0042] The ratio of the thickness of the adhesive layer to the thickness of the thermally conductive sheet layer (thickness of the adhesive layer / thickness of the thermally conductive sheet layer) is preferably 0.05 to 0.50, or 0.05 to 0.25. By setting the thickness ratio in this range, the thermal conductivity is likely to be improved.

[0043] When the adhesive layer has a multi-layer structure, the thickness of the adhesive layer refers to the total thickness of all layers (for example, the support layer and adhesive layer) that constitute the adhesive layer.

[0044] <Adhesive Layer> The adhesive layer is composed of an adhesive. The adhesive constituting the adhesive layer is not particularly limited, and examples thereof include an acrylic adhesive, an epoxy adhesive, a urethane adhesive, a polyimide adhesive, and a silicone adhesive. From the viewpoint of heat resistance, etc., the adhesive constituting the adhesive layer is preferably a polyimide adhesive.

[0045] The adhesive layer is preferably formed of a thermosetting adhesive. When the adhesive layer is formed of a thermosetting adhesive, it is easy to achieve both peel strength and insulating properties. When the adhesive layer is formed of a thermosetting adhesive, the elastic modulus of the adhesive layer at 25°C and the elastic modulus of the adhesive layer at 80°C described above refer to the elastic modulus of the adhesive layer after the thermosetting adhesive is heat-cured at 120°C for 15 minutes.

[0046] The adhesive layer is a layer obtained by applying an adhesive to a support layer (and drying it as needed) or by applying a film-like adhesive to a support layer. Such an adhesive layer is cured as needed after the thermally conductive adhesive sheet is applied to the adherend.

[0047] The adhesive layer may contain other components, such as a thermally conductive material, a dispersant, a curing agent, a tackifier, a plasticizer, a flame retardant, an antioxidant, a stabilizer, a colorant, and a binder component.

[0048] The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm to 50 μm, more preferably 1 μm to 20 μm, even more preferably 1 μm to 15 μm, even more preferably 1 μm to 10 μm, and particularly preferably 1 μm to 8 μm. By setting the thickness to such a range, thermal conductivity is likely to be improved.

[0049] <Support Layer> The support layer is usually a resin film. Examples of resins constituting the resin film include polyethylene terephthalate, triacetyl cellulose, polyethylene naphthalate, polymethyl methacrylate, polycarbonate, polyimide, polyethylene, polypropylene, polyvinyl alcohol, and polyvinyl chloride. From the viewpoint of improving the dielectric breakdown voltage resistance, the support layer is preferably a polyimide-based film.

[0050] The thickness of the support layer is not particularly limited, but is preferably 1 μm to 100 μm, more preferably 5 μm to 50 μm, even more preferably 5 μm to 30 μm, and even more preferably 5 μm to 15 μm. By setting the thickness to such a range, it is easy to achieve both a high breakdown voltage and thermal conductivity.

[0051] Here, it is preferable that the adhesive layer and the support layer satisfy the following condition (iii): (iii) [Modulus of elasticity of support layer at 25°C]>[Modulus of elasticity of adhesive layer at 25°C]

[0052] More specifically, the ratio of the elastic modulus of the support layer at 25°C to the elastic modulus of the adhesive layer at 25°C (elastic modulus of support layer / elastic modulus of adhesive layer) is not particularly limited, but is preferably greater than 1, 2 or more, or 5 or more, and is preferably 1000 or less, 500 or less, 100 or less, 20 or less, or 10 or less. More specifically, this ratio is preferably greater than 1 and 1000 or less, more preferably 2 to 500, even more preferably 2 to 100, even more preferably 2 to 20, and particularly preferably 2 to 10.

[0053] The modulus of elasticity of the support layer at 25° C. is not particularly limited, but is preferably 20 MPa to 10,000 MPa.

[0054] When the modulus of elasticity of the adhesive layer and the modulus of elasticity of the support layer are in this relationship, the shear strength and other properties of the thermally conductive adhesive sheet are likely to be improved.

[0055] <<<Physical Properties / Characteristics>>> <<Shear Strength>> The thermally conductive adhesive sheet is not particularly limited, but the shear strength measured under the following measurement conditions is preferably 0.5 MPa or more, more preferably 1.0 MPa or more, and even more preferably 1.2 MPa or more. (Measurement Conditions) Shear strength is measured using a universal tensile tester. A thermally conductive adhesive sheet (20 mm wide x 20 mm long) is sandwiched on both sides between a stainless steel plate (30 mm wide x 30 mm long x 1 mm thick) and an alumina plate (20 mm wide x 20 mm long x 1 mm thick), and heated and pressed at 120°C and a pressure of 1.0 MPa for 15 minutes to prepare a test piece. One end of the stainless steel plate was gripped with the lower chuck of a universal tensile testing machine (RTF-1310 manufactured by A&D Co., Ltd.), and the end face of the test piece facing the lower chuck was pressed into the test piece with a stainless steel jig at a test speed of 2 mm / min. The maximum load at which the test piece broke was taken as the shear strength.

[0056] <<Thermal Conductivity>> The thermal conductive adhesive sheet is not particularly limited, but the thermal conductivity measured under the following measurement conditions is preferably 0.4 W / (m·K) to 10 W / (m·K), more preferably 0.6 W / (m·K) to 10 W / (m·K), even more preferably 0.8 W / (m·K) to 10 W / (m·K), even more preferably 1.0 W / (m·K) to 10 W / (m·K), and particularly preferably 1.2 W / (m·K) to 10 W / (m·K). (Measurement Conditions) Thermal conductivity is measured using a steady-state method. A test piece is prepared by punching out a 50 mm diameter circle from the measurement object. The test piece is measured using a steady-state thermal conductivity measuring device (GH-1, manufactured by Advance Riko Co., Ltd.), and the obtained measured value is the thermal conductivity.

[0057] <<Breakdown Voltage>> The breakdown voltage of the thermally conductive adhesive sheet, measured under the following measurement conditions, is preferably 600 V or higher, and more preferably 1000 V or higher. (Measurement Conditions) The breakdown voltage is measured in accordance with JIS C 2110-1. The thermally conductive adhesive sheet is subjected to a constant voltage for 60 seconds to evaluate for the presence or absence of breakdown, and the maximum voltage at which the thermally conductive adhesive sheet does not experience breakdown is taken as the breakdown voltage. Note that, as a voltage condition, for example, the initial voltage is 100 V, and the test is performed while increasing the voltage in increments of 100 V.

[0058] <<<Manufacturing Method>>> The thermally conductive adhesive sheet can be manufactured by a conventionally known method, for example, by preparing an adhesive layer in advance and attaching the adhesive layer to the main surface of the thermally conductive sheet, or by applying an adhesive (or an adhesive solution prepared by diluting the adhesive with an organic solvent) to the main surface of the thermally conductive sheet and drying as needed (and further laminating a support layer or another adhesive layer as needed).

[0059] <<<Applications>>> The thermally conductive adhesive sheet according to the present disclosure is preferably used in applications where it is attached to a heat dissipation member (or heat-generating member), and more preferably used in applications where it is interposed between a heat dissipation member and a heat-generating member. Examples of heat dissipation members include heat sinks. Examples of heat-generating members include semiconductor elements, laser elements, coils, power devices, electrostatic chucks, motors, etc. More specifically, the thermally conductive adhesive sheet according to the present disclosure is preferably applied to members constituting semiconductor devices, laser light irradiation devices, semiconductor manufacturing equipment, etc. In other words, the technology according to the present disclosure may provide a member for a semiconductor device, a member for a laser light irradiation device, or a member for a semiconductor manufacturing equipment that includes a thermally conductive adhesive sheet.

[0060] The thermally conductive adhesive sheet according to the present disclosure is used by adhering it to a heat dissipation member (or a heat-generating member) and then curing the adhesive layer as necessary.

[0061] <<<Raw Materials>>> <<Adhesive Layer>> <Adhesives> (Adhesive 1: Polyimide-based adhesive) Polyimide resin (SMP-5008PGA, manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass (Adhesive 2: Polyimide-based adhesive) Polyimide resin (SMP-5008PGA, manufactured by Shin-Etsu Chemical Co., Ltd.) 20 parts by mass Bisphenol A-type epoxy resin (JER828, manufactured by Mitsubishi Chemical Corporation) 77 parts by mass Curing agent (Curesol 2E4MZ, manufactured by Shikoku Chemical Co., Ltd.) 3 parts by mass (Adhesive 3: Olefin-based adhesive) Olefin resin (Tuftec H1041, manufactured by Asahi Kasei Chemicals Corporation) 100 parts by mass

[0062] <Support layer> Polyimide film (Kapton 20EN, 50EN, 100EN, 200EN, manufactured by DuPont-Toray Co., Ltd.) Elastic modulus at 25°C: 5000 MPa (The thickness of the support layer is shown in Tables 1 and 2.)

[0063] <<Thermal Conductive Sheet Layer>> Sheets 1 to 5 were manufactured as thermal conductive sheet layers. The thermal conductivity of Sheets 1 to 5 was 1.0 W / (m·K) or more. The manufacturing method for each sheet is described below. The thickness of each sheet was adjusted to the values ​​shown in Tables 1 and 2.

[0064] <Sheet 1> (Raw materials for sheet 1) Fluororubber (Viton A-100, manufactured by Chemours) 45 parts by mass Pitch-based carbon fiber having an average fiber length of 120 μm 45 parts by mass Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diameter 15 nm, length 10 μm) 10 parts by mass (Preparation of sheet 1) A solution obtained by dissolving and dispersing each raw material in 300 parts by mass of isophorone was poured into a hollow rectangular prism-shaped Teflon (registered trademark) resin mold (100 mm x 50 mm) and heated at 120 ° C for 1 hour under reduced pressure conditions, followed by heating and drying at 200 ° C for 1 hour to produce a molded product. The molded product was removed from the resin mold and then cut with a slicer to a predetermined thickness to obtain sheet 1.

[0065] <Sheets 2 to 4> Sheets 2 to 4 were produced in the same manner as Sheet 1, except that the raw materials were changed. The raw materials used in the production of Sheets 2 to 4 are shown below. (Raw materials for sheet 2) Fluoro rubber (Viton A-100, manufactured by Chemours) 70 parts by mass Pitch-based carbon fiber having an average fiber length of 120 μm 20 parts by mass Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diameter 15 nm, length 10 μm) 15 parts by mass (Raw materials for sheet 3) Fluoro rubber (Viton A-100, manufactured by Chemours) 80 parts by mass Pitch-based carbon fiber having an average fiber length of 120 μm 5 parts by mass Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diameter 15 nm, length 10 μm) 15 parts by mass (Raw materials for sheet 4) Fluoro rubber (Viton A-500, manufactured by Chemours) 20 parts by mass Pitch-based carbon fiber having an average fiber length of 120 μm 75 parts by mass Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diameter 15 nm, length 10 μm) 5 parts by mass

[0066] <Sheet 5> (Raw materials for sheet 5) Silicone resin (one-component liquid silicone) containing alkenyl groups at both ends of the molecular chain 44.5 parts by mass Platinum catalyst 0.5 parts by mass Pitch-based carbon fiber with an average fiber length of 120 μm 45 parts by mass Carbon nanotubes (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., diameter 15 nm, length 10 μm) 10 parts by mass (Preparation of sheet 5) The solution in which each raw material was kneaded and dispersed was poured into a hollow rectangular prism-shaped Teflon (registered trademark) resin mold (100 mm × 50 mm), heated under reduced pressure at 120 ° C. for 1 hour to harden, and a molded body was produced. After removing the molded body from the resin mold, it was cut with a slicer to a predetermined thickness to obtain sheet 1.

[0067] <<<Production of Thermally Conductive Adhesive Sheets>>> <<Examples 1, 3-14, Comparative Example 1>> Tables 1 and 2 show the combinations of raw materials used. An adhesive solution was prepared by dissolving and mixing adhesives (Adhesives 1 to 3) in 300 parts by mass of tetrahydrofuran. The adhesive solution was applied to both main surfaces of the support layer and dried at 150°C for 3 minutes to produce a double-sided adhesive tape having a support and adhesive layers on both sides of the support layer. Next, double-sided adhesive tape was attached to both main surfaces of the thermally conductive sheet layer to produce the thermally conductive adhesive sheets of Examples 1, 3-14, and Comparative Example 1. The thickness of each layer is as shown in Tables 1 and 2. <<Example 2>> Table 1 shows the combinations of raw materials used. An adhesive solution was prepared by dissolving and mixing Adhesive 1 in 300 parts by mass of tetrahydrofuran. The adhesive solution was applied to a release-treated PET film and dried at 150°C for 3 minutes to produce an adhesive sheet with a single adhesive layer. Next, the obtained adhesive sheets were attached to both main surfaces of the thermally conductive sheet layer, and the release-treated PET film was peeled off to produce the thermally conductive adhesive sheet according to Example 2. The thickness of each layer is as shown in Table 1.

[0068] <<<Physical Properties / Evaluation>>> Based on the methods described above, the modulus of elasticity of each adhesive layer at 25°C and 80°C, and the modulus of elasticity of each thermally conductive sheet at 25°C and 80°C were measured. Note that the modulus of elasticity of each adhesive layer in Examples 1, 3 to 14 and Comparative Example 1 was measured using a single-layer pressure-sensitive adhesive layer obtained by forming an adhesive layer under the same conditions as the manufacturing method of each adhesive layer, except that the support layer was changed to a release-treated PET film, and then peeling off the film.

[0069] The shear strength, thermal resistance, and breakdown voltage of the thermally conductive adhesive sheets were measured according to the methods described above, and evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 1 and 2.

[0070] (Shear strength) ⊚: Shear strength is 1.2 MPa or more. ◯: Shear strength is 0.8 MPa or more and less than 1.2 MPa. Δ: Shear strength is 0.5 MPa or more and less than 0.8 MPa. ×: Shear strength is less than 0.5 MPa.

[0071] (Thermal conductivity) ◎: The thermal conductivity value is 1.0 W / (m·K) or more. ◯: The thermal conductivity value is 0.7 W / (m·K) or more and less than 1.0 W / (m·K). △: The thermal conductivity value is 0.4 W / (m·K) or more and less than 0.7 W / (m·K). ×: The thermal conductivity value is less than 0.4 W / (m·K).

[0072] (Breakdown voltage) ⊚: Breakdown voltage is 1000V or more. ◯: Breakdown voltage is 600V or more and less than 1000V. ×: Breakdown voltage is less than 600V.

[0073] For shear strength, thermal resistance, and breakdown voltage, samples with an x ​​rating were judged to be unsatisfactory.

[0074]

[0075]

[0076] The thermally conductive adhesive sheet according to the present invention has excellent peel strength and is therefore preferably used for application to heat dissipation components such as heat sinks, or heat-generating components such as semiconductor elements, laser elements, coils, power devices, and motors. CROSS-REFERENCE TO RELATED APPLICATIONS

[0077] This application claims priority based on Japanese Patent Application No. 2023-170431, filed with the Japan Patent Office on September 29, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A thermally conductive adhesive sheet comprising a thermally conductive sheet layer and an adhesive layer provided on at least one main surface of the thermally conductive sheet layer, the adhesive layer including an adhesive layer formed from an adhesive, and satisfying at least one of the following conditions (i) and (ii): (i) [Modulus of elasticity of the adhesive layer at 25°C]>[Modulus of elasticity of the thermally conductive sheet layer at 25°C] (ii) [Modulus of elasticity of the adhesive layer at 80°C]>[Modulus of elasticity of the thermally conductive sheet layer at 80°C] 2. The thermally conductive adhesive sheet according to claim 1, wherein the thermally conductive sheet layer has an elastic modulus of 10.0 MPa to 500.0 MPa at 25°C.

3. The thermally conductive adhesive sheet according to claim 1, wherein the shear strength measured under the following measurement conditions is 0.5 MPa or more. (Measurement conditions) The shear strength is measured using a universal tensile tester. A thermally conductive adhesive sheet (20 mm wide x 20 mm long) is sandwiched between a stainless steel plate (30 mm wide x 30 mm long x 1 mm thick) and an alumina plate (20 mm wide x 20 mm long x 1 mm thick) on both sides, and heated and pressed for 15 minutes at 120°C and a pressure of 1.0 MPa to prepare a test piece. One end of the stainless steel plate is held by the lower chuck of the universal tensile tester (RTF-1310, manufactured by A&D Co., Ltd.), and the end surface of the test piece facing the lower chuck is pressed with a stainless steel jig at a test speed of 2 mm / min. The maximum load at which the test piece breaks is taken as the shear strength.

4. The thermally conductive adhesive sheet according to claim 1, wherein the ratio of the thickness of the adhesive layer to the thickness of the thermally conductive sheet layer (thickness of the adhesive layer / thickness of the thermally conductive sheet layer) is 0.05 to 0.

50.

5. The thermally conductive adhesive sheet according to claim 1, wherein said adhesive layer is provided on both main surfaces of said thermally conductive sheet layer.

6. The thermally conductive adhesive sheet according to claim 1, having a thermal conductivity of 0.4 W / (m·K) to 10 W / (m·K).

7. The thermally conductive adhesive sheet according to claim 1, having a dielectric breakdown voltage of 600 V or more.

8. A thermally conductive adhesive sheet according to any one of claims 1 to 7, wherein the adhesive layer comprises a support layer and the adhesive layer provided on both main surfaces of the support layer.

9. The thermally conductive adhesive sheet according to claim 8, which satisfies the following condition (iii): (iii) [the elastic modulus of the support layer at 25° C.]>[the elastic modulus of the adhesive layer at 25° C.] 10. The thermally conductive adhesive sheet according to claim 8, wherein the ratio of the elastic modulus of the support layer at 25°C to the elastic modulus of the adhesive layer at 25°C (elastic modulus of the support layer / elastic modulus of the adhesive layer) is greater than 2 and less than 100.

11. The thermally conductive adhesive sheet according to claim 8, wherein the thickness of the support layer is from 5 μm to 50 μm.

12. The thermally conductive adhesive sheet according to claim 8, wherein the adhesive layer has a thickness of 1 μm to 20 μm.

13. A component for semiconductor manufacturing equipment, comprising the thermally conductive adhesive sheet according to claim 1.

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