TW202340375A - Thermally conductive silicone composition, thermally conductive silicone sheet, and method for manufacturing said sheet - Google Patents

Abstract

This thermally conductive silicone composition contains a silicone polymer (A), thermally conductive particles (B), and a silane coupling agent (C). The thermally conductive particles (B) include aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3), and the thermally conductive particles (B) account for 20 vol% to 80 vol% when the composition constitutes 100 vol.%. The silane coupling agent (C) is a compound represented by R1 nSi(OR2)4-n (where R1 is an alkyl group having 3 to 16 carbon atoms, R2 is an alkyl group having 1 to 2 carbon atoms, and n is between 1 and 3). The thermally conductive silicone composition contains an amount of the silane coupling agent that results in a surface coverage of 150% or more, as calculated from the BET specific surface area of the thermally conductive particles (B) as well as the blended amount and minimum coverage area of the silane coupling agent. As a result, provided are: a thermally conductive silicone composition that has low compressive stress, places a low load on electronic components during mounting, and is highly reliable; a thermally conductive silicone sheet; and a method for manufacturing said sheet.

Description

Thermal conductive polysiloxane composition, thermal conductive polysiloxane sheet and manufacturing method thereof

The invention relates to a low compressive stress thermally conductive polysiloxane composition, a thermally conductive polysiloxane sheet and a manufacturing method thereof.

In recent years, the performance of semiconductors such as CPUs has been significantly improved, and the amount of heat generated has also become huge. Therefore, a heat sink is installed in an electronic component that generates heat, and a thermally conductive sheet is used to improve the adhesion between the semiconductor and the heat sink. Patent Documents 1 and 2 propose a thermally conductive sheet in which aluminum hydroxide particles with different particle sizes are used as the main component of thermally conductive particles. Patent Document 3 proposes surface treatment of aluminum hydroxide particles with titanate and then using the aluminum hydroxide particles as a heat conductive material. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2011-089079 [Patent Document 2] Japanese Patent Application Publication No. 2011-178821 [Patent Document 3] Specification No. WO2016-068240

[Problem to be solved by the invention]

However, in the above-mentioned Patent Documents 1 and 2, since they do not contain crushed alumina particles and contain a large amount of aluminum hydroxide particles relative to the total amount of thermally conductive particles, there is a high compressive stress and a load on electronic components during mounting. Bigger problem. Furthermore, in Patent Document 3, since the aluminum hydroxide particles are surface-treated with titanate, there is a problem in terms of heat resistance, and further improvement is required.

In order to solve the above problems in the past, the present invention provides a low -composite stress, low load on electronic parts during installation, high heat resistance, and high reliability. Silicone sheets and methods of making the same. [Technical means to solve the problem]

The thermally conductive polysiloxane composition of the present invention contains polysiloxane matrix polymer (A), thermally conductive particles (B), and silane coupling agent (C), and is characterized by: the above-mentioned polysiloxane matrix polymer ( A) is addition-curable dimethylpolysiloxane, and the thermally conductive particles (B) contain aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3), and Contains particles that have not been surface-treated in advance. When the thermally conductive polysiloxane composition is 100 vol.%, the thermally conductive particles (B) are 20 vol.% or more and 80 vol.% or less. The silane coupling agent (C) is represented by R ¹ _n Si (OR ² ) _4-n (where R ¹ is an alkyl group with 3 to 16 carbon atoms, R ² is an alkyl group with 1 or 2 carbon atoms, and n is 1 to 3) The compound containing the thermally conductive particle (B) is calculated based on the BET specific surface area of the particles without prior surface treatment and the minimum coverage area and blending amount of the silane coupling agent using the following formula (Formula 1) The surface coverage rate is more than 150%. [Formula 1]

The thermally conductive polysilicone sheet of the present invention is characterized in that it is formed by shaping the above thermally conductive polysiloxane composition into a sheet and hardening it.

The manufacturing method of the thermally conductive polysilicone sheet of the present invention is characterized in that the composite of the thermally conductive polysiloxane composition is formed into a sheet and then heated and hardened. [Effects of the invention]

The thermally conductive polysiloxane composition of the present invention contains polysiloxane matrix polymer (A), thermally conductive particles (B), and silane coupling agent (C). The polysiloxane matrix polymer (A) is addition hardened. Type dimethyl polysiloxane, the thermally conductive particles (B) contain aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3). When the thermally conductive polysiloxane is When the oxygen composition is 100 vol.%, the thermally conductive particles (B) are 20 vol.% or more and 80 vol.% or less. This provides a system with low compressive stress and low load on electronic components during installation. , a thermally conductive polysiloxane composition with high heat resistance and high reliability, a thermally conductive polysiloxane sheet and a manufacturing method thereof.

The thermally conductive polysiloxane composition of the present invention contains polysiloxane matrix polymer (A), thermally conductive particles (B), and silane coupling agent (C). The polysiloxane matrix polymer (A) is an addition hardening type. Dimethylpolysiloxane. The thermally conductive polysiloxane composition is preferably the following, for example. (A1) Basic polymer component: linear organopolysiloxane, which contains an average of more than two alkenyl groups bonded to silicon atoms at both ends of the molecular chain in one molecule. (A2) Cross-linking component: Organohydrogenated polysiloxane containing an average of more than 2 hydrogen atoms bonded to silicon atoms in 1 molecule relative to 1 mol of alkenyl groups bonded to silicon atoms in the above A1 component The amount is less than 3 moles. (B) Thermal conductive particles: Containing aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3), when the thermal conductive polysiloxane composition is 100 vol.% , the thermally conductive particles (B) are 20 vol.% or more and 80 vol.% or less. The addition amount of the thermally conductive particles is preferably 30 to 80 vol.%, more preferably 40 to 80 vol.%, and still more preferably 45 to 75 vol.%. In this way, the thermal conductivity can be improved, and it can be preferably used as a heat sink TIM (Thermal Interface Material) between the heat generating part and the heat dissipating part of electronic components. The thermally conductive particles include particles that have not been surface-treated in advance, and preferably all the thermally conductive particles have not been surface-treated in advance. (C) Silane coupling agent: R ¹ _n Si (OR ² ) _4-n (where R ¹ is an alkyl group with 3 to 16 carbon atoms, R ² is an alkyl group with 1 or 2 carbon atoms, and n is 1 to 3 ), and contains a compound represented by the above-mentioned thermally conductive particles (B) based on the BET specific surface area of the above-mentioned thermally conductive particles that have not been surface-treated in advance and the minimum coverage area and blending amount of the silane coupling agent. The above formula (numeric formula 1) The calculated surface coverage rate is above 150%. The minimum coverage area can be obtained from the information submitted by the silane coupling agent manufacturer. In addition, it can also be calculated based on the molecular weight of silane. The above-mentioned surface coverage rate is preferably 160% or more, more preferably 170% or more, and further preferably 180% or more. (D) Catalyst component: 0.01 to 1000 ppm based on metal atomic weight relative to the A1 component. The catalyst is preferably a platinum-based compound.

In the above composition, a commercially available product can be used as the polysiloxane matrix polymer (A). This commercial product is usually divided into A agent and B agent. One contains the above-mentioned component (A1) and the catalyst component (D), and the other contains the cross-linking component (A2) and the hardening reaction inhibitor.

The average particle diameter of the aluminum hydroxide particles (B1) is preferably from 10 μm to 110 μm, more preferably from 15 to 100 μm, and still more preferably from 20 to 90 μm. Moreover, when the total volume of the thermally conductive particles is 100 vol.%, the amount of aluminum hydroxide particles (B1) added is preferably 20 vol.% or more and 80 vol.% or less, more preferably 30 to 75 vol.%. %, and more preferably 40 to 70 vol.%. The shape of the aluminum hydroxide particles is preferably block-like.

The average particle diameter of the spherical alumina particles (B2) is preferably from 1 μm to 110 μm, more preferably from 2 to 100 μm. A plurality of spherical alumina particles (B2) may be used in combination with those having an average particle diameter of 1 to 30 μm and those having an average particle diameter exceeding 30 μm and being 110 μm or less. Furthermore, in this specification, "spherical alumina" refers to true spherical alumina obtained by a melting method.

The average particle diameter of the crushed alumina particles (B3) is preferably 10 μm or less, more preferably 0.01 to 10 μm, further preferably 0.1 to 8 μm. By using the crushed alumina particles (B3) with a small particle size in combination, a composite suitable for processing can be obtained, and it can also achieve both thermal conductivity and low load.

When the total volume of thermally conductive particles is 100 vol.%, the total amount of spherical alumina particles (B2) and crushed alumina particles (B3) is preferably 20 vol.% or more and 80 vol.% or less, more preferably Preferably, it is 30-70 vol.%, More preferably, it is 40-60 vol.%.

The addition amount of the spherical alumina particles (B2) and the crushed alumina particles (B3) is preferably set to B2≦B3. This makes it possible to obtain a composite that is suitable for processing and can achieve both thermal conductivity and low load.

The thermally conductive polysilicone sheet of the present invention is formed by shaping the above thermally conductive polysiloxane composition into a sheet and hardening it. As long as it is a sheet, it can be preferably used as a heat sink TIM (Thermal Interface Material) between the heat generating part and the heat dissipating part of electronic components.

The instantaneous load value at 50% compression of a thermally conductive polysiloxane sheet with a diameter of 28.6 mm and an initial thickness of 1 mm is preferably 900 N or less, more preferably 880 N or less. This reduces compressive stress (lower load) and reduces the load on electronic components during installation.

The thermal conductivity of the thermally conductive polysiloxane sheet is preferably 2 W/mK or more, further preferably 2.1 W/mK or more, and more preferably 2.2 W/mK or more. The upper limit value is preferably 20 W/mK or less.

Regarding the heat resistance of the thermally conductive polysiloxane sheet, when aged in air at 100°C, the change after 100 hours from the initial Shore hardness of 00 is preferably within ±10, and more preferably within Within ±8, and more preferably within ±6. If the heat resistance is higher, the reliability will also be higher.

The manufacturing method of the thermally conductive polysiloxane sheet of the present invention preferably includes the following steps. (1) Manufacturing steps of thermally conductive polysiloxane composition Measure the prescribed amounts of addition-curable dimethyl polysiloxane (such as commercially available agents A and B), thermally conductive particles (B) (containing aluminum hydroxide particles (B1), spherical alumina particles ( B2), crushed alumina particles (B3)), and silane coupling agent (C) are mixed to prepare a composite (mixed raw material). Some of the thermally conductive particles used in the present invention can also be mixed with a silane coupling agent in advance for pretreatment. The purpose of using thermally conductive particles (B) without surface treatment in advance is to reduce costs. In addition, the method of mixing the thermally conductive particles (B) and the silane coupling agent (C) without surface treatment during compounding is generally called integral blending. The present invention adopts this method. Furthermore, titanate pretreatment products are not included in the present invention. Titanate pretreated products have low heat resistance and are therefore not suitable. (2) Sheet forming steps The above-mentioned composite (mixed raw material) is formed into a sheet by rolling or punching. The thickness of the thermally conductive sheet is preferably in the range of 0.2 to 10 mm. (3) Heating and hardening step The preferred heating and hardening conditions for the above-mentioned sheet are a temperature of 70 to 250°C and a time of 1 to 15 minutes.

Each component is explained below. (1) Basic polymer component (A1 component) The basic polymer component is an organopolysiloxane containing more than two alkenyl groups bonded to silicon atoms in one molecule. The organopolysiloxane containing more than two alkenyl groups is the polysiloxane rubber of the present invention. The main agent (basic polymer component) in the composition. The organopolysiloxane has in one molecule two or more alkenyl groups bonded to silicon atoms such as vinyl groups and allyl groups with 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms. From the viewpoint of workability, hardenability, etc., the viscosity is preferably 10 to 100,000 mPa‧s at 25°C, and particularly preferably 100 to 10,000 mPa‧s.

Specifically, an organopolysiloxane represented by the following general formula (Chemical Formula 1) containing an average of two or more alkenyl groups bonded to silicon atoms at both ends of the molecular chain per molecule is used. It is a linear organopolysiloxane with side chains terminated by alkyl groups. From the viewpoint of workability, hardenability, etc., the ideal viscosity at 25°C is 10 to 100,000 mPa‧s. Furthermore, the linear organopolysiloxane may also contain a small amount of branched structure (trifunctional siloxane unit) in the molecular chain. [Chemical 1] In the formula, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group that is the same as or different from each other and does not have an aliphatic unsaturated bond, R ² is an alkenyl group, and k is 0 or a positive integer. Among them, the unsubstituted or substituted monovalent hydrocarbon group without an aliphatic unsaturated bond as ^R1 is, for example, preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms. Specifically, , can be listed: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl, etc. Alkyl; aryl groups such as phenyl, tolyl, xylyl, naphthyl, etc.; aralkyl groups such as benzyl, phenylethyl, phenylpropyl, etc.; and some or all of the hydrogen atoms of these groups are replaced by fluorine, Those substituted by halogen atoms such as bromine and chlorine, and cyano groups, such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl and other halogen-substituted alkyl groups, cyanoethyl, etc. The alkenyl group of R ² is, for example, preferably an alkenyl group having 2 to 6 carbon atoms, particularly preferably 2 to 3 carbon atoms. Specific examples include vinyl, allyl, propenyl, isopropenyl, and butene. group, isobutenyl, hexenyl, cyclohexenyl, etc., preferably vinyl. In the general formula (1), k is usually 0 or a positive integer satisfying 0≦k≦10000, preferably an integer satisfying 5≦k≦2000, and more preferably an integer satisfying 10≦k≦1200.

The organopolysiloxane as component A1 may also have 3 or more carbon atoms in one molecule, usually 3 to 30, preferably about 3 to 20, such as vinyl, allyl, etc. 2 to 8. It is particularly preferred to use the organopolysiloxanes of 2 to 6 with alkenyl groups bonded to silicon atoms. The molecular structure can be any of linear, cyclic, branched, and three-dimensional network molecular structures. Preferably, the main chain is composed of repeats of two organosiloxane units and both ends of the molecular chain are terminated with three organosiloxy groups. The viscosity at 25°C is 10~100,000 mPa‧s, especially preferably 100~10,000 mPa‧ s linear organopolysiloxane. Alkenyl groups can be bonded to any part of the molecule. For example, those bonded to silicon atoms at the end of the molecular chain or at the non-end of the molecular chain (in the middle of the molecular chain) may also be included. Among them, in terms of workability, curability, etc., it is preferable to have 1 to 3 alkenyl groups on the silicon atoms at both ends of the molecular chain represented by the following general formula (Chemical Formula 2) (wherein, with the molecule When the total number of alkenyl groups bonded to the silicon atom at the end of the chain does not reach 3, there must be at least one alkenyl group bonded to the silicon atom at the non-end of the molecular chain (midway through the molecular chain) (for example, as a diorganosilicon Linear organopolysiloxane (substituents in the oxyalkane unit)) and the viscosity at 25°C is 10 to 100,000 mPa‧s as mentioned above. Furthermore, the linear organopolysiloxane may also contain a small amount of branched structure (trifunctional siloxane unit) in the molecular chain. [Chemicalization 2] In the formula, R ³ is an unsubstituted or substituted monovalent hydrocarbon group that is the same as or different from each other, and at least one of them is an alkenyl group. R ⁴ is an unsubstituted or substituted monovalent hydrocarbon group that is the same as or different from each other and does not have an aliphatic unsaturated bond, R ⁵ is an alkenyl group, and l and m are 0 or positive integers. Among them, the monovalent hydrocarbon group of R ³ is preferably one having 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Specific examples include: methyl, ethyl, propyl, isopropyl, and butyl. , isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl and other alkyl groups; phenyl, tolyl, xylyl, naphthyl and other aryl groups; Aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and octenyl ; Or some or all of the hydrogen atoms of these groups are substituted by halogen atoms such as fluorine, bromine, chlorine, or cyano groups, such as chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, and other halogen-substituted alkyl groups. Or cyanoethyl, etc.

In addition, the monovalent hydrocarbon group of R ⁴ is preferably one having 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Examples of the monovalent hydrocarbon group include the same ones as the specific examples of R ¹ described above, except that they do not contain an alkenyl group. The alkenyl group of R ⁵ is, for example, preferably one having 2 to 6 carbon atoms, and particularly preferably one having 2 to 3 carbon atoms. Specifically, the alkenyl group is the same as R ² of the above formula (Chemical Formula 1), and preferably it is ethylene. base. l and m are usually 0 or a positive integer that satisfies 0＜l+m≦10000, preferably 5≦l+m≦2000, more preferably 10≦l+m≦1200, and 0＜l/(l+ m)≦0.2, preferably an integer of 0.0011≦l/(l+m)≦0.1.

(2) Cross-linked component (A2 component) The organohydrogenated polysiloxane of the A2 component of the present invention functions as a cross-linking agent, and a hardened product is formed by an addition reaction (hydrosilylation) between the SiH group in the component and the alkenyl group in the A1 component. The organohydrogenated polysiloxane can be any organohydrogenated polysiloxane as long as it has more than two hydrogen atoms (i.e., SiH groups) bonded to silicon atoms in one molecule. The organohydrogenated polysiloxane The molecular structure of the oxalane can be any of linear, cyclic, branched, or three-dimensional network structures. The number of silicon atoms in one molecule (ie, the degree of polymerization) is 2 to 1000, which is particularly preferred. It is about 2 to 300.

The position of the silicon atom to which the hydrogen atom is bonded is not particularly limited. It can be at the end of the molecular chain or at the non-end (midway). Examples of organic groups other than hydrogen atoms bonded to silicon atoms include unsubstituted or substituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds and the same as ^R1 of the general formula (Chemical Formula 1) above. .

Examples of the organohydrogenated polysiloxane as component A2 include those having the following structures.

In the above formula, R ⁶ is the same or different hydrogen, alkyl group, phenyl group, epoxy group, acrylyl group, methacrylyl group, alkoxy group, and at least two of them are hydrogen. L is an integer from 0 to 1,000, particularly preferably an integer from 0 to 300, and M is an integer from 1 to 200.

(3) Thermal conductive inorganic particles (component B) The thermally conductive inorganic particles of component B are as described above. Furthermore, the alumina is preferably α-alumina with a purity of 99.5% or more. The average particle size is the D50 (median diameter) of the volume-based cumulative particle size distribution measured by laser diffraction light scattering. As this measuring device, there is, for example, a laser diffraction/scattering inorganic particle distribution measuring device LA-950S2 manufactured by Horiba Manufacturing Co., Ltd.

(4) Silane coupling agent (C component) Silane coupling agent (C) uses R ¹ _n Si (OR ² ) _4-n (where R ¹ is an alkyl group with 3 to 16 carbon atoms, and R ² is 1 or 2 alkyl group, n is an alkoxysilane compound represented by 1 to 3). The alkoxysilane compound may be a partial hydrolyzate thereof. Examples include: propyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, and octyltriethoxysilane Oxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane Silane compounds such as silane. The above-mentioned silane compounds may be used alone or in combination of two or more. Silane coupling agent (C component) is used as a surface treatment agent for thermally conductive inorganic particles during the preparation of the composite or subsequent thermal hardening treatment. Alkoxysilane and single-terminal silanolsiloxane can also be used together. The so-called surface treatment here includes, in addition to covalent bonding, adsorption, etc.

(5) Catalyst component (D component) The catalyst component of component D is a component that promotes hardening. As component D, a catalyst used in silicon hydrogenation reaction can be used. Examples include: platinum black, chloroplatin (II) acid, chloroplatinic acid, the reactant of chloroplatinic acid and a monohydric alcohol, complexes of chloroplatinic acid and olefins or vinylsiloxane, platinum bisacetate acetate Platinum group metal catalysts such as platinum series catalysts, palladium series catalysts, rhodium series catalysts, etc. The blending amount of component D only needs to be the amount required for hardening, and can be adjusted appropriately depending on the required hardening speed, etc. It is preferable to add 0.01 to 1000 ppm based on the weight of metal atoms relative to the A1 component.

(6) Other ingredients In the composition of the present invention, ingredients other than the above may be blended as necessary. For example, examples of the hardening reaction inhibitor include acetylene compounds such as 1-ethynyl-1-hexanol and 3-butyn-1-ol, various nitrogen compounds, organophosphorus compounds, oxime compounds, organochlorine compounds, and the like. The usage amount is preferably about 0.01 to 1 part by mass relative to 100 parts by mass of component (A). This is added to either the A agent or the B agent of the commercial product. In addition, inorganic pigments such as iron oxide can be added as colorants.

Below, a diagram is used for explanation. In the following diagrams, the same symbols represent the same thing. FIG. 1 is a schematic cross-sectional view of a thermally conductive sheet according to an embodiment of the present invention being assembled into a heat dissipation structure 30 . The thermally conductive sheet 31b dissipates heat generated by electronic components 33 such as semiconductor elements, and is fixed to the main surface 32a of the heat sink 32 facing the electronic component 33, and is sandwiched between the electronic component 33 and the heat sink 32. In addition, the heat conduction sheet 31 a is sandwiched between the heat sink 32 and the heat sink 35 . Furthermore, the thermal conductive sheets 31a and 31b together with the heat sink 32 constitute a heat dissipation member that dissipates the heat of the electronic component 33. The heat sink 32 is formed in a square plate shape, for example, and has a main surface 32a facing the electronic component 33, and a side wall 32b erected along the outer periphery of the main surface 32a. The heat sink 32 is provided with a heat conductive sheet 31b on the main surface 32a surrounded by the side wall 32b, and a heat dissipation base 35 is provided on the other surface 32c opposite to the main surface 32a with the heat conductive sheet 31a interposed therebetween. The electronic component 33 is a semiconductor element such as a BGA, for example, and is mounted on the wiring board 34 .

Figure 2 is a scanning electron microscope (SEM) photograph (magnification: 600 times) of bulk aluminum hydroxide particles (B1) according to one embodiment of the present invention. The massive aluminum hydroxide particles are produced by the Bayer process and are already commercially available (for example, the trade name "BW53" manufactured by Nippon Light Metal Co., Ltd., with an average particle size of 54 μm).

Figure 3 is a scanning electron microscope (SEM) photograph (magnification: 10,000 times) of spherical alumina (B2) according to one embodiment of the present invention. The spherical alumina is produced by a melting method and is already commercially available (for example, the trade name "AZ2-75" manufactured by Nippon Steel Chemical Materials Co., Ltd., with an average particle size of 2 μm). Figure 4 is a scanning electron microscope (SEM) photograph of polygonal or circular alumina not included in the spherical alumina (B2) of the present invention.

Figure 5 is a scanning electron microscope (SEM) photograph (magnification: 6,000 times) of crushed alumina (B3) according to one embodiment of the present invention. This crushed alumina is produced by the Bayer process and is commercially available (for example, it is manufactured by Sumitomo Chemical Company under the trade name "ALM-41-01", with an average particle size of 1 to 2 μm). [Example]

Hereinafter, examples will be used for explanation. The present invention is not limited to the examples. ＜Compression load＞ The measurement method of compressive load is based on ASTM D575-91:2012. 6 is a schematic side cross-sectional view of a compressive load measuring device used in one embodiment of the present invention. This compressive load measuring device 1 includes a sample stage 2 and a load cell 6. The thermally conductive sheet sample 4 is sandwiched between aluminum plates 3 and 5, installed as shown in FIG. 6, and compressed to a predetermined thickness by the load cell 6. Record the maximum load value when the thickness is compressed to 50%, and the load value after maintaining the compression for 1 minute. Measurement conditions Sample: round (diameter 28.6 mm, thickness 1 mm) Compression rate: 50% Aluminum plate size: round (diameter 28.6 mm) (compression side) Compression speed: 5 mm/min Compression method: TRIGGER method (the point where the load is perceived to be 2 N is used as the starting position for determination) Measuring device: Made by Aikoh Engineering, MODEL-1310NW (load cell 200 kgf) ＜Thermal Conductivity＞ The thermal conductivity of the thermally conductive sheet was measured using Hot Disk (according to ISO 22007-2:2022). As shown in FIG. 7A , the thermal conductivity measuring device 11 sandwiched the polyimide film sensor 12 with two thermally conductive sheet samples 13a and 13b, and applied constant power to the sensor 12 to cause it to generate constant heat. Thermal characteristics are analyzed based on the temperature rise value of the sensor 12 . The diameter of the front end 14 of the sensor 12 is 7 mm. As shown in FIG. 7B , it forms a double helix structure of electrodes, and an electrode 15 for applying current and an electrode for resistance value (temperature measurement electrode) 16 are arranged at the lower part. Thermal conductivity is calculated using the following equation (Equation 2).

[Formula 2] λ: Thermal conductivity (W/m‧K) Po: Constant power (W) r: Radius of the sensor (m) τ: α: Thermal diffusivity of the sample (m ² /s) t: Measurement time (s) D (τ): Dimensionless function of τ ΔT (τ): Temperature rise of the sensor (K) ＜Processing Properties> Since the unhardened composite is a clay-like solid, the ability to process it is judged by its rolling formability. The evaluation criteria are as follows. A: It has good rolling formability. B: Calendering is difficult, but it can be formed. C: Cannot be rolled and formed. <Hardness> The hardness of the hardened sheet is measured according to Shore 00 specified in ASTM D2240-15 (2021). <Heat resistance> Place the polysiloxane sheet into a hot air circulation oven at 100°C. After 100 hours, take it out and cool it to room temperature. Find the hardness and initial hardness measured according to Shore 00 specified in ASTM D2240. the amount of change. <Surface coverage ratio> It is calculated using the above formula (Formula 1) based on the BET specific surface area of the thermally conductive particles that have not been surface-treated in advance and the minimum coverage area and blending amount of the silane coupling agent.

(Examples 1 to 7, Comparative Examples 1 to 3) (1) Silicone-based polymer components (A1, A2) Commercially available two-liquid room-temperature curing polysilicone polymers were used as the silicone-based polymer components. . The A agent of the two-liquid room temperature curable polysiloxane polymer is pre-added with a base polymer component and a platinum metal catalyst, and the B agent is pre-added with a base polymer component, a cross-linking component and a hardening reaction inhibitor. It is an addition-hardening polydimethylsiloxane. Agent A is represented by A1 and agent B is represented by A2. (2) Thermal conductive inorganic particles (B) B1: Aluminum hydroxide (i) Block shape, average particle diameter (D50) 43 μm, titanate pretreated product (commercially available product) (ii) Block shape, average particle size (D50) 49 μm, untreated product (commercially available product), specific surface area 0.18 m ² /g (iii) Massive, average particle size (D50) 75 μm, untreated product (commercially available product), specific surface area 0.1 m ² /g B2: Spherical alumina (i) Average particle diameter (D50) 75 μm, untreated product (commercial product), specific surface area 0.2 m ² /g (ii) Average particle diameter (D50) 6 μm, untreated Product (commercially available product), specific surface area 0.8 m ² /g B3: Crushed alumina (i) average particle size (D50) 2.1 μm, untreated product (commercially available product), specific surface area 1.8 m ² /g (3 ) Silane coupling agent (C) Use decyltrimethoxysilane (commercially available product), and the minimum coating area is 298 m ² /g. (4) Thermal conductive sheet forming: uniformly mix the two uncured liquid room temperature curing polysiloxane polymers, thermally conductive inorganic particles and silane coupling agent to form a composite, and sandwich it between polyester (PET) films and rolled to a thickness of 1 mm, and then hardened at 100°C for 10 minutes. The above conditions and results are shown in Tables 1 to 3. Furthermore, in Tables 1 to 3, the specific gravity when the volume fraction is calculated based on parts by mass (g) is as follows. Polysilicone polymer: specific gravity 0.97 Silane coupling agent: specific gravity 0.90 Aluminum hydroxide: specific gravity 2.42 Alumina: specific gravity 3.98

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Addition reaction polysiloxane polymer A1 (mass parts) 50 50 50 50 50 A2 (mass parts) 50 50 50 50 50 Aluminum hydroxide (B1) Bulk, titanate treated, (D50) 43 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) - - - - - - - - - - Bulk, untreated, (D50) 49 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) 240 45 240 45 250 45 250 45 250 45 Bulk, untreated, (D50) 75 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) - - - - - - - - - - Alumina (B2) Spherical, untreated, (D50) 75 μm (part by mass) Volume fraction relative to the entire thermally conductive particles (v.%) 140 16 150 17 160 18 100 11 - - Spherical, untreated, (D50) 6 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) - - - - - - 60 7 160 18 Aluminum oxide (B3) crushed, untreated, (D50) 2.1 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) 340 39 330 38 340 37 340 37 340 37 Total thermal conductive particles (parts by mass) 720 720 750 750 750 Total thermal conductive particles (v.%) 67 67 68 68 68 Silane coupling agent (C) (mass parts) 5.5 6.0 6.0 6.0 6.0 Surface coverage rate (%) expressed by the above formula (Formula 1) 228 257 249 237 219 Thermal conductivity of hardened sheet (W/mK) 2.5 2.6 2.7 2.6 2.4 Hardness (Shore 00) 45 40 46 45 52 Load value (peak) (N) 798 789 811 785 846 Heat resistance 100℃×100 h, change in hardness (Shore 00) -2 +2 +2 -1 -2

[Table 2] Example 6 Example 7 Comparative example 1 Comparative example 2 Comparative example 3 Addition reaction polysiloxane polymer A1 (mass parts) 50 50 50 50 50 A2 (mass parts) 50 50 50 50 50 Aluminum hydroxide (B1) Bulk, titanate treated, (D50) 43 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) - - - - 240 45 - - - - Bulk, untreated, (D50) 49 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) 250 45 - - - - 240 46 240 46 Bulk, untreated, (D50) 75 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) - - 400 62 - - - - - - Alumina (B2) Spherical, untreated, (D50) 75 μm (part by mass) Volume fraction relative to the entire thermally conductive particles (v.%) - - - - 150 17 140 16 140 16 Spherical, untreated, (D50) 6 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) 160 18 200 19 - - - - - - Aluminum oxide (B3) crushed, untreated, (D50) 2.1 μm (mass part) Volume fraction relative to the entire thermally conductive particles (v.%) 340 37 200 19 330 38 330 38 330 38 Total thermal conductive particles (parts by mass) 750 800 720 710 710 Total thermal conductive particles (v.%) 68 71 68 67 67 Silane coupling agent (C) (mass parts) 5.0 4.5 1.9 2.1 3.2 Surface coverage rate (%) expressed by the above formula (Formula 1) 183 210 91 91 137 Thermal conductivity of hardened sheet (W/mK) 2.5 2.5 2.4 2.6 2.4 Hardness (Shore 00) 56 47 38 58 51 Load value (peak) (N) 867 717 699 1036 905 Heat resistance 100℃×100 h, change in hardness (Shore 00) -2 +4 +25 +1 +3

[table 3] Heat resistance 100℃, change in hardness (Shore 00) Oven processing time (hours) 0 100 250 500 Example 1 - -2 0 +3 Example 2 - +2 +4 +5 Example 3 - 0 +2 +3 Example 4 - -1 +3 -4 Example 5 - -2 -2 -3 Example 6 - -2 -3 -1 Example 7 - +4 +7 +6 Comparative example 1 - +25 +52 +54 Comparative example 2 - +1 +5 +16 Comparative example 3 - +3 +8 +7

As shown in Tables 1 to 3, it was confirmed that in each of the examples, the thermal conductivity was high, the steady-state load value was low, and the compression relaxation was large. By slowly compressing, it was confirmed that clamping with a low load was possible. The damage to the body is small. Since the load value is low and it is soft, it can better follow the unevenness of electronic parts and the operability of the chip is good. On the other hand, in Comparative Example 1, since aluminum hydroxide particles were used as a titanate pretreated product, the heat resistance was not good. In addition, in Comparative Examples 2 and 3, since the surface treatment coverage rate of the silane coupling agent on the heat conductive particles is low, the load value is high and the compressive stress is high. There is a problem of greater load on electronic components during installation. [Industrial availability]

The thermally conductive sheet of the present invention can be used as a heat sink between the heat generating part and the heat dissipating part of electronic components such as semiconductors, LEDs, and home appliances, information communication modules including optical communication equipment, and automotive applications.

1: Compression load measuring device 2: Sample table 3,5:Aluminum plate 4: Thermal conductive sheet sample 6: Load cell 11: Thermal conductivity measuring device 12: Sensor 13a, 13b: Thermal conductive sheet sample 14: Sensor front end 15: Electrode for applying current 16: Electrode for resistance value (electrode for temperature measurement) 30:Heat dissipation structure 31a, 31b: Thermal conductive sheet 32:Heat sink 32b: Radiator side wall 33: Electronic parts 34:Wiring board 35: Cooling seat

[Fig. 1] is a schematic cross-sectional view showing a method of using the thermally conductive polysiloxane sheet according to one embodiment of the present invention. [Fig. 2] is a scanning electron microscope (SEM) photograph (magnification: 600 times) of the massive aluminum hydroxide particles (B1) according to one embodiment of the present invention. [Fig. 3] is a scanning electron microscope (SEM) photograph (magnification: 10,000 times) of spherical alumina (B2) according to one embodiment of the present invention. [Fig. 4] is a scanning electron microscope (SEM) photograph of polygonal or circular alumina not included in the spherical alumina (B2) of the present invention. [Fig. 5] is a scanning electron microscope (SEM) photograph (magnification 6,000 times) of crushed alumina (B3) according to one embodiment of the present invention. [Fig. 6] is a schematic side cross-sectional view of a compressive load measuring device used in one embodiment of the present invention. 7A-B are explanatory diagrams showing a method of measuring thermal conductivity used in one embodiment of the present invention.

30:Heat dissipation structure

31a, 31b: Thermal conductive sheet

32:Heat sink

32a: Main side

32b: Radiator side wall

32c: The other side opposite to the main side

33: Electronic parts

34:Wiring board

35: Cooling seat

Claims (10)

A thermally conductive polysiloxane composition, which contains polysiloxane matrix polymer (A), thermally conductive particles (B), and silane coupling agent (C), and is characterized by: the above polysiloxane matrix polymer ( A) is addition-curable dimethylpolysiloxane, and the thermally conductive particles (B) contain aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3), and Contains particles that have not been surface-treated in advance. When the thermally conductive polysiloxane composition is 100 vol.%, the thermally conductive particles (B) are 20 vol.% or more and 80 vol.% or less. The silane coupling agent (C) is represented by R ¹ _n Si (OR ² ) _4-n (where R ¹ is an alkyl group with 3 to 16 carbon atoms, R ² is an alkyl group with 1 or 2 carbon atoms, and n is 1 to 3) The compound containing the thermally conductive particle (B) is calculated based on the BET specific surface area of the particles without prior surface treatment and the minimum coverage area and blending amount of the silane coupling agent using the following formula (Formula 1) The surface coverage rate is more than 150%, [Formula 1] . The thermally conductive polysiloxane composition of claim 1, wherein the average particle diameter of the aluminum hydroxide particles (B1) is 10 μm or more and 110 μm or less. When the total volume of the thermally conductive particles is 100 vol.% , it is 20 vol.% or more and 80 vol.% or less. The thermally conductive polysiloxane composition of claim 1, wherein the average particle diameter of the above-mentioned spherical alumina particles (B2) is 1 μm or more and 110 μm or less, and the average particle diameter of the above-mentioned broken alumina particles (B3) is 10 μm or less, when the total volume of the thermally conductive particles is 100 vol.%, the total amount of B2+B3 is 20 vol.% or more and 80 vol.% or less. The thermally conductive polysiloxane composition of claim 3, wherein the added amounts of the above-mentioned spherical alumina particles (B2) and the above-mentioned crushed alumina particles (B3) are B2≦B3. A thermally conductive polysiloxane sheet, which is formed by shaping the thermally conductive polysiloxane composition of any one of claims 1 to 4 into a sheet and hardening it. Such as claim 5 for a thermally conductive polysiloxane sheet, wherein the thermally conductive polysiloxane sheet has a diameter of 28.6 mm and an initial thickness of 1 mm. The instantaneous load value at 50% compression is 900 N or less. The thermally conductive polysiloxane sheet of claim 5, wherein the thermal conductivity of the thermally conductive polysiloxane sheet is 2 W/mK or more. For example, the thermally conductive polysiloxane sheet of claim 5, wherein the heat resistance of the thermally conductive polysiloxane sheet is: when aged in air at 100°C, after 100 hours from the initial Shore hardness of 00 The variation is within ±10. A method for manufacturing a thermally conductive polysiloxane sheet according to any one of claims 5 to 8, characterized in that: a composite of a thermally conductive polysiloxane composition is formed into a sheet and is heated and hardened, and the thermal conductivity The polysilicone composition contains a polysilicone matrix polymer (A), thermally conductive particles (B), and a silane coupling agent (C). The polysilicone matrix polymer (A) is an addition-hardening dimethylpolymer. Siloxane, the above-mentioned thermally conductive particles (B) contain aluminum hydroxide particles (B1), spherical alumina particles (B2), and crushed alumina particles (B3), and contain particles that have not been surface-treated in advance. When the thermally conductive polysiloxy composition is 100 vol.%, the thermally conductive particles (B) are 20 vol.% or more and 80 vol.% or less, and the silane coupling agent (C) is R ¹ _n Si (OR ² ) _4-n (where R ¹ is an alkyl group having 3 to 16 carbon atoms, R ² is an alkyl group having 1 or 2 carbon atoms, and n is 1 to 3), and contains thermally conductive particles according to the above ( B) The BET specific surface area of the above-mentioned particles that have not been surface-treated in advance and the minimum coverage area and blending amount of the silane coupling agent are calculated using the following formula (Formula 1) to calculate the surface coverage rate of 150% or more, [Formula 1] . For example, the method for manufacturing a thermally conductive polysiloxane sheet according to claim 9, wherein the heating and hardening conditions of the above-mentioned sheet are a temperature of 70 to 250°C and a time of 1 to 15 minutes.