Thermally conductive silicone gel composition, thermally conductive silicone sheet, and method for manufacturing the same

Abstract

(A) an organopolysiloxane containing at least two alkenyl groups in one molecule, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms, (C) a platinum group metal-based curing catalyst: a catalyst amount, and for every 100 parts by mass of the total of components (A)-(C), (D) 200-600 parts by mass of aluminum hydroxide particles which are thermally conductive particles, and when this is used as a parameter, (D-1) more than 40 mass% and less than 75 mass% of aluminum hydroxide particles with a particle diameter (D50) of 30 μm or more, and (D-2) more than 25 mass% and less than 60 mass% of aluminum hydroxide particles with a particle diameter (D50) of less than 30 μm, and the relative permittivity at a frequency of 1 MHz of the mutual dielectric bridge method is 5.0 or less, and the Shore-OO hardness is 5 to 60. Thus, a silicone gel composition is provided that uses a material not subject to GHS classification, has high safety, flexibility, low dielectric constant, and is also thermally conductive.

Description

Technology Field

[0001] The present invention relates to a thermally conductive silicone gel composition that is desirable for interposing between a heat-generating part and a heat dissipator, such as in electrical or electronic components. More preferably, the invention relates to a silicone gel composition that is low dielectric constant and also thermally conductive, a thermally conductive silicone sheet, and a method for manufacturing the same. Background Technology

[0002] Recent improvements in the performance of semiconductors, such as CPUs, are remarkable, and consequently, the amount of heat generated is also increasing significantly. Therefore, heat sinks are installed in electronic components that generate heat, and thermally conductive silicone gels are used between heat sources, such as semiconductors, and heat sinks. Due to the miniaturization, high performance, and high integration of devices, thermally conductive silicone gels are required to possess properties such as electromagnetic wave absorption and noise prevention in addition to thermal conductivity. Furthermore, due to recent global environmental issues, a system (Globally Harmonized System of Classification and Labelling of Chemicals; hereinafter referred to as "GHS") related to classification criteria and labeling methods (such as SDS) for the hazardous nature of substances to be handled is also required. Thermally conductive fillers such as alumina, crystalline silica, and magnesium oxide fall under the GHS and are considered undesirable. Patent Document 1 proposes a low dielectric constant sheet formed by adding crystalline silica particles and aluminum hydroxide particles to an acrylic resin. Patent documents 2 to 4 propose adding alumina particles and a plurality of types of aluminum hydroxide particles to an organopolysiloxane to form a thermally conductive silicon composition. Prior art literature

[0003] Japanese Published Patent No. 2020-077777 Japanese Patent No. 5304588 Japanese Published Patent No. 2020-002236 Japanese Published Patent No. 2020-066713 The problem to be solved

[0004] However, Patent Document 1 contains crystalline silica and is a material subject to GHS classification, and Patent Documents 2 to 4 contain alumina particles and are materials subject to GHS classification, and there is no problem with making them low dielectric constant sheets.

[0005] To solve the above-mentioned conventional problems, the present invention provides a silicone gel composition, a thermally conductive silicone sheet, and a method for manufacturing the same, which uses a material not subject to GHS classification, has high safety, flexibility, low dielectric constant, and is also thermally conductive. means of solving the problem

[0006] The thermally conductive silicone gel composition of the present invention is,

[0007] (A) As a component, an organopolysiloxane comprising at least two alkenyl groups in one molecule

[0008] (B) As a component, an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms

[0009] (C) As a component, platinum group metal-based hardening catalyst: amount of catalyst

[0010] For a total of 100 parts by mass of the above (A)-(C) components,

[0011] (D) As a component, it comprises 200 to 600 parts by mass of aluminum hydroxide particles which are thermally conductive particles, and when the aluminum hydroxide particles are 100% by mass,

[0012] (D-1) Aluminum hydroxide particles with a median diameter (D50) of 30 µm or more, exceeding 40 mass% and less than 75 mass%

[0013] (D-2) Contains 25 mass% or more and 60 mass% or less of aluminum hydroxide particles with a median diameter (D50) of less than 30㎛, and

[0014] Based on JIS K6911:2006, it is characterized by having a relative permittivity of 5.0 or less at a frequency of 1 MHz of the mutual induction bridge method and a Shore-OO hardness of 5 to 60.

[0015] The thermally conductive silicone sheet of the present invention is formed by sheet molding the above-mentioned thermally conductive silicone gel composition.

[0016] The method for manufacturing a thermally conductive silicone sheet according to the present invention is,

[0017] (A) Component: Organopolysiloxane containing at least two alkenyl groups in one molecule

[0018] (B) Component: Organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms

[0019] (C) Component: Platinum group metal-based hardening catalyst: Catalyst amount and,

[0020] For a total of 100 parts by mass of the above (A)-(C) components,

[0021] (D) Component: Contains 200 to 600 parts by mass of aluminum hydroxide particles which are thermally conductive particles, and when the aluminum hydroxide particles are 100% by mass,

[0022] (D-1) Aluminum hydroxide particles with a median diameter (D50) of 30 µm or more, exceeding 40 mass% and less than 75 mass%

[0023] (D-2) Aluminum hydroxide particles with a median diameter (D50) of less than 30㎛: 25 mass% or more and 60 mass% or less

[0024] The method is characterized by mixing, sheet forming, and curing, and, in accordance with JIS K6911:2006, manufacturing a thermally conductive silicon sheet having a relative permittivity of 5.0 or less at a frequency of 1 MHz of the cross-dielectric bridge method and a Shore-OO hardness of 5 to 60. Effects of the invention

[0025] The present invention can provide a silicone gel composition, a thermally conductive silicone sheet, and a method for manufacturing the same, which contains the above (A)-(D) components, uses a material not subject to GHS classification by having a relative permittivity of 5.0 or less at a frequency of 1 MHz of the cross-dielectric bridge method in accordance with JIS K6911:2006 and a Shore-OO hardness of 5 to 60, has high safety, flexibility, low permittivity, and is also thermally conductive. Brief explanation of the drawing

[0026] [Fig. 1] Fig. 1 (A)-(B) is an explanatory diagram showing a method for measuring the thermal conductivity of a sample in one embodiment of the present invention. Specific details for implementing the invention

[0027] The component (A) of the present invention is an organopolysiloxane containing at least two alkenyl groups in one molecule. This component is a component that serves as the base polymer of a silicone gel composition. Preferably, it has at least two alkenyl groups in one molecule and has a viscosity of 100 to 10,000 Pa·s. The viscosity is the value obtained after 30 seconds using a Type B rotational viscometer at a rotational speed of 20 rpm and 23°C.

[0028] The component (B) of the present invention is an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms. This component is a crosslinking component of a silicone gel composition. Preferably, it contains an amount such that the number of moles of hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups derived from component (A). The number of moles is more preferably 0.1 to 4.0 times, and even more preferably 0.1 to 3.0 times.

[0029] The (C) component of the present invention is a platinum group metal-based curing catalyst. This catalyst is an addition curing reaction catalyst. The content is sufficient as the amount of catalyst, and specifically, it is preferably 0.1 to 1,000 ppm in terms of mass equivalent of platinum group metal elements with respect to the (A) component.

[0030] The (D) component of the present invention is aluminum hydroxide particles of thermally conductive particles.

[0031] Component (D) is included in an amount of 200 to 600 parts by mass per 100 parts by mass of the total of components (A)-(C), and the aluminum hydroxide particles have multiple types of median diameters (D50), and when the total of components (D) is 100% by mass,

[0032] (D-1) Aluminum hydroxide particles with a median diameter (D50) of 30 µm or more, exceeding 40 mass% and less than 75 mass%

[0033] (D-2) Aluminum hydroxide particles with a median diameter (D50) of less than 30㎛ make up 25% or more and 60% or less.

[0034] Preferably, component (D-1) is greater than 45 mass% and less than 75 mass%, and component (D-2) is greater than 25 mass% and less than 55 mass%. By using aluminum hydroxide particles with different median diameters (D50) in this way, small particles exist between large particles, and the material is packed in a state close to close packing, and the thermal conductivity is increased. The particle diameter was set to D50 (median diameter), which is 50% of the cumulative particle size distribution based on volume in the particle size distribution measurement by laser diffraction light scattering method. As an example of this measuring instrument, there is the laser diffraction / scattering particle distribution measuring device LA-950S2 manufactured by Horiba Seisakusho Co., Ltd.

[0035] The thermally conductive silicone gel composition of the present invention, in accordance with JIS K6911:2006, has a relative permittivity of 5.0 or less at a frequency of 1 MHz for the cross-dielectric bridge method, preferably 4.8 or less. As a result, electromagnetic wave absorption and noise prevention properties are good. The lower limit of the relative permittivity is 2.6 or more, preferably 3.0 or more.

[0036] The thermally conductive silicone gel composition of the present invention has a Shore-OO hardness of 5 to 60, preferably 10 to 55. This allows for flexibility. Flexibility improves the adhesion between a heating element, such as a semiconductor, and a heat dissipator, and is desirable as a Thermal Interface Material (TIM).

[0037] The thermally conductive silicone gel composition of the present invention may further add a surface treatment agent for thermally conductive particles as component (E). Surface treatment agents include titanate-based coupling agents, aluminate-based coupling agents, stearic acid-based coupling agents, epoxy-based silane coupling agents, alkyl-based silane coupling agents, etc. Among these, alkyl-based silane coupling agents are preferred, and R a Si(OR') 4-a At least one silane coupling agent selected from an alkoxysilane compound represented by (where R is an unsubstituted or substituted organic group having 6 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1), its partial hydrolysate, and an alkoxy group-containing silicone comprising an unsubstituted or substituted organic group having 6 to 12 carbon atoms is preferred. Examples include silane compounds such as hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, and dodecyltriethoxysilane. The above silane compounds may be used in combination of one or more types. As a surface treatment agent, an alkoxysilane and a single-terminated silanosiloxane may be used together. The surface treatment referred to herein includes adsorption in addition to covalent bonding.

[0038] The surface treatment agent may be pretreated by mixing it with the thermally conductive particles in advance (pretreatment method), or it may be added when mixing the matrix resin and the thermally conductive particles [integral blend method]. In both treatment methods, it is preferable to add 0.01 to 10 parts by mass of the surface treatment agent per 100 parts by mass of the thermally conductive particles. Surface treatment has the effect of making it easier to fill into the matrix resin.

[0039] In the thermally conductive silicone gel composition of the present invention, other components may be incorporated as needed. For example, an addition reaction control agent such as 1-ethynyl-1-cyclohexanol, a heat resistance enhancer such as Bengala, titanium oxide, or cerium oxide, a flame retardant, a flame retardant aid, etc. may be added. Organic or inorganic particle pigments may be added for the purpose of coloring or color adjustment. As a material added for the purpose of filler surface treatment, an alkoxy group-containing silicone may be added.

[0040] In addition, as component (F), thermally conductive particles other than component (D) above that are not subject to GHS classification may be included. For example, it is preferable to add hexagonal boron nitride, aluminum nitride, amorphous silica, calcium carbonate, etc. Since alumina particles, crystalline silica particles, and magnesium oxide particles are subject to GHS classification, it is preferable not to add them.

[0041] The thermal conductivity of the above thermally conductive silicone gel composition is preferably 2.0 W / mK or less, more preferably 0.5 to 2.0 W / mK, and even more preferably 0.7 to 1.8 W / mK. By doing so, it is possible to provide a silicone gel composition that balances safety, flexibility, low dielectric constant, and thermal conductivity using a material not subject to GHS classification.

[0042] The specific gravity of the above thermally conductive silicone gel composition is preferably 2.2 or less, and more preferably 2.0 or less. This results in a lightweight TIM material. The lower limit of the specific gravity of the above composition is preferably 1.2 or more, and more preferably 1.4 or more.

[0043] The thermally conductive silicone gel composition of the present invention is preferably a sheet-molded thermally conductive silicone sheet. If it is sheet-molded, it is preferred for TIM applications.

[0044] The method for manufacturing a thermally conductive silicone sheet of the present invention involves mixing the above components (A), (B), (C), and (D) and other components added as needed, forming a sheet, and curing it, and, in accordance with JIS K6911:2006, manufacturing a thermally conductive silicone sheet having a relative permittivity of 5.0 or less at a frequency of 1 MHz of a cross-dielectric bridge method and a Shore-OO hardness of 5 to 60.

[0045] It is preferable to form a sheet by mixing the above raw material components, placing them on a polyethylene terephthalate (PET) film, rolling to form a sheet, and curing at 80 to 120°C for 5 to 40 minutes.

[0046] <Example>

[0047] The present invention will be explained with reference to the following examples. The present invention is not limited to the examples. Various parameters were measured by the following methods.

[0048] Thermal conductivity

[0049] The thermal conductivity of the thermally conductive grease was measured by a hot disk (in accordance with ISO / CD 22007-2). As shown in (A) of FIG. 1, this thermal conductivity measuring device (1) places a polyimide film sensor (2) between two samples (3a, 3b), applies constant power to the sensor (2) to generate a constant amount of heat, and analyzes the thermal characteristics from the temperature rise value of the sensor (2). The sensor (2) has a tip (4) with a diameter of 7 mm and, as shown in (B) of FIG. 1, has a double helix structure of electrodes, and an electrode (5) for applied current and an electrode (6) for resistance value (temperature measuring electrode) are arranged at the bottom. The thermal conductivity is calculated by the following equation (Equation 1).

[0050] [Number 1]

[0051]

[0052] Non-permittivity

[0053] In accordance with JIS K6911:2006, the relative permittivity at a frequency of 1 MHz using the mutual dielectric bridge method was measured using a sheet with a thickness of 2 mm.

[0054] <Shore-OO 경도>

[0055] In accordance with ASTM D2240, four sheets of 3 mm thickness were stacked and measured using an automatic dumeter stand.

[0056] (Example 1)

[0057] 1. Ingredients

[0058] A two-component room-temperature curing silicone polymer was used as components (A) to (C). In component A of this two-component room-temperature curing silicone polymer, component (A) and component (C) were added in advance, and in component B, component (A) and component (B) were added in advance.

[0059] Liquid A viscosity: 3000 mPas

[0060] Liquid B viscosity: 1000 mPas

[0061] A total of 100 parts by mass of a two-component room-temperature curing silicone polymer

[0062] (D) component

[0063] (D-1) Aluminum hydroxide particles with a median diameter (D50) of 55㎛, “No surface treatment” (Hygilite H-10, manufactured by Showa Denko Co., Ltd.): 240 weight

[0064] (D-2a) Aluminum hydroxide particles with a median diameter (D50) of 4 µm (CL-303, manufactured by Sumitomo Chemical Co., Ltd., treated with an epoxy silane coupling agent): 100 parts by weight

[0065] 2. Mixing and molding methods

[0066] The above raw material components were mixed, placed on a PET film, rolled to form a sheet, and cured at 100°C for 10 minutes. The thickness of the thermally conductive silicone sheet was set to 2 mm and 3 mm.

[0067] The thermally conductive silicon sheet obtained as described above was evaluated. The conditions and results are summarized in Table 1 below.

[0068] (Example 2)

[0069] 150 parts by mass of component (D-1),

[0070] (D-2b) 100 parts by mass of aluminum hydroxide particles “no surface treatment” (Hygillite H-32, manufactured by Showa Denko Co., Ltd.) having a median diameter (D50) of 10㎛,

[0071] (F) 100 parts by mass of amorphous silica with a median diameter (D50) of 7 μm

[0072] Except for the part that was done, it was carried out in the same way as Example 1.

[0073] (Example 3)

[0074] 92 parts by mass of component (D-1),

[0075] 118 parts by mass of component (D-2a)

[0076] Except for the part that was done, it was carried out in the same way as Example 1.

[0077] (Example 4)

[0078] A two-component room-temperature curing silicone polymer is used as components (A) to (C), and

[0079] Liquid A viscosity: 300 mPas,

[0080] Liquid B viscosity: 300 mPas

[0081] A total of 100 parts by mass,

[0082] 250 parts by mass of component (D-1),

[0083] 130 parts by mass of component (D-2a),

[0084] (D-2c) 70 parts by mass of aluminum hydroxide particles with a median diameter (D50) of 18 μm that have been titanate-coupled (manufactured by Showa Denko Co., Ltd., trade name "Hyzilite H-31T"),

[0085] (E) 1 part by mass of decyltrimethoxysilane as component

[0086] Except for the part that was done, it was carried out in the same way as Example 1.

[0087] The above conditions and results are summarized in Table 1.

[0088] [Table 1]

[0089]

[0090] (Comparative Examples 1–5)

[0091] Except for what is shown in Table 2 below, the procedure was carried out in the same manner as Example 1.

[0092] [Table 2]

[0093]

[0094] (Note: Comparative Examples 1 and 2 could not be filled with (D-1) and (D-2), making sheet molding impossible.)

[0095] From the above results, it was confirmed that Examples 1 to 4 use materials not subject to GHS classification and are silicone gel compositions with balanced safety, flexibility, low dielectric constant, and thermal conductivity.

[0096] [Industrial Applicability]

[0097] The thermally conductive silicone gel composition of the present invention is preferred for interposing between a heat-generating part and a heat dissipator, such as in electrical and electronic components. Explanation of the symbols

[0098] 1 : Thermal conductivity measuring device 2 : Sensor 3a, 3b: Samples 4: Tip of the sensor 5: Electrode for applied current 6 : Electrode for resistance (electrode for temperature measurement)

Claims

Claim 1 (A) Component: an organopolysiloxane containing at least two alkenyl groups in one molecule; (B) Component: an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to a silicon atom; and (C) component: platinum group metal-based hardening catalyst: includes an amount of catalyst, and for every 100 parts by mass of the total of components (A)-(C), (D) component: includes 200 to 600 parts by mass of aluminum hydroxide particles which are thermally conductive particles, and when the aluminum hydroxide particles are set to 100 mass%, (D-1) aluminum hydroxide particles having a median diameter (D50) of 30 μm or more that is 50% of the cumulative particle size distribution by volume in the measurement of particle size distribution by laser diffraction light scattering method, contain more than 40 mass% and less than 75 mass%, and (D-2) aluminum hydroxide particles having a median diameter (D50) of less than 30 μm that is 50% of the cumulative particle size distribution by volume in the measurement of particle size distribution by laser diffraction light scattering method, contain 25 mass% or more and 60 mass% or less, and in accordance with JIS K6911:2006, mutually A thermally conductive silicone gel composition having a relative permittivity of 5.0 or less at a frequency of 1 MHz of the mutual induction bridge method and a Shore-OO hardness of 5 to 60. Claim 2 In claim 1, the organopolysiloxane of component (A) is a thermally conductive silicone gel composition having a viscosity of 100 to 10,000 Pa·s. Claim 3 A thermally conductive silicone gel composition according to claim 1, wherein the organohydrogenpolysiloxane of component (B) is in an amount such that the number of moles of hydrogen atoms directly bonded to silicon atoms is 0.1 to 5.0 times the number of moles of alkenyl groups derived from component (A). Claim 4 A thermally conductive silicone gel composition according to claim 1, further comprising, as component (E), a surface treatment agent for thermally conductive particles. Claim 5 A thermally conductive silicone gel composition according to claim 4, wherein the surface treatment agent is at least one coupling agent selected from titanate-based coupling agents, aluminate-based coupling agents, stearic acid-based coupling agents, epoxy-based silane coupling agents, and alkyl-based silane coupling agents. Claim 6 In claim 5, the alkyl-based silane coupling agent is R a Si(OR') 4-a A thermally conductive silicone gel composition comprising at least one silane coupling agent selected from an alkoxysilane compound represented by (R is an unsubstituted or substituted organic group having 6 to 12 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1), a partial hydrolyzate thereof, and an alkoxy group-containing silicone comprising an unsubstituted or substituted organic group having 6 to 12 carbon atoms. Claim 7 In claim 4, the surface treatment agent is a thermally conductive silicone gel composition added in an amount of 0.01 to 10 parts by mass per 100 parts by mass of thermally conductive particles. Claim 8 A thermally conductive silicone gel composition according to claim 1, further comprising, as component (F), at least one thermally conductive particle selected from hexagonal boron nitride, aluminum nitride, amorphous silica, and calcium carbonate. Claim 9 A thermally conductive silicone gel composition according to claim 1, wherein the thermal conductivity of the thermally conductive silicone gel composition is 2.0 W / mK or less. Claim 10 A thermally conductive silicone gel composition according to claim 1, wherein the specific gravity of the thermally conductive silicone gel composition is 2.2 or less. Claim 11 A thermally conductive silicone sheet in which a thermally conductive silicone gel composition described in any one of claims 1 to 10 is sheet-molded. Claim 12 A method for manufacturing a thermally conductive silicon sheet as described in claim 11, comprising: (A) component: an organopolysiloxane containing at least two alkenyl groups in one molecule; (B) component: an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms; (C) component: a platinum group metal-based curing catalyst; and, for every 100 parts by mass of the sum of the catalyst amount and the above (A)-(C) components, (D) component: 200 to 600 parts by mass of aluminum hydroxide particles which are thermally conductive particles, wherein when the aluminum hydroxide particles are 100 mass%, (D-1) in measuring the particle size distribution by laser diffraction light scattering method, the aluminum hydroxide particles having a median diameter (D50) of 30 μm or more that is 50% of the cumulative particle size distribution by volume basis, are greater than 40 mass% and less than 75 mass%; (D-2) in measuring the particle size distribution by laser diffraction light scattering method, A method for manufacturing a thermally conductive silicon sheet, comprising mixing 25 mass% or more and 60 mass% or less of aluminum hydroxide particles having a median diameter (D50) of less than 30 μm, which is 50% of the cumulative particle size distribution based on volume, forming a sheet, and curing, and manufacturing a thermally conductive silicon sheet having a relative permittivity of 5.0 or less at a frequency of 1 MHz of a cross-dielectric bridge method in accordance with JIS K6911:2006 and a Shore-OO hardness of 5 to 60. Claim 13 delete

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