Heat-conductive composition, heat-conductive sheet using the same, and production method of the latter

Abstract

To provide a heat-conductive composition which has high heat-conductivity and a suppressed compression load value, a heat-conductive sheet using the same, and a production method of the latter.SOLUTION: A heat-conductive composition comprises a matrix resin (A) and heat-conductive inorganic particles (B). When the content of the matrix resin (A) is taken as 100 mass%, the content of an addition-curable silicone polymer (A1) is 30 mass% or more and less than 100 mass% and the content of a nonreactive silicone oil (A2) is more than 0 mass% and 60 mass% or less. The heat-conductive inorganic particles (B) comprises the following amounts of components based on 100 pts.mass of the matrix resin (A): 400-1,000 pts.mass of the thermally conductive inorganic particles having median diameters of D50 of less than 10 μm; 400-1,000 pts.mass of the thermally conductive inorganic particles having D50 of 10 μm or more and less than 100 μm; and 800-1,500 pts.mass of the thermally conductive inorganic particles having D50 of 100 μm or more. The heat-conductive composition has an instantaneous load value of 500 N or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive composition suitable for being interposed between a heat-generating portion of an electric or electronic component or the like and a heat sink, a thermally conductive sheet using the same, and a method for producing the same. [Background technology]

[0002] In recent years, the performance of semiconductors such as CPUs has improved dramatically, resulting in enormous increases in the amount of heat generated. For this reason, heat-generating electronic components are fitted with heat sinks, and thermally conductive sheets are used to improve adhesion between the semiconductor and the heat sink. As devices become smaller, their performance improves, and they become more highly integrated, thermally conductive sheets are required to be soft and have high thermal conductivity. Patent Documents 1 and 2 propose polysiloxane compositions containing large-diameter aluminum nitride particles and small-diameter aluminum nitride particles or alumina particles. Patent Documents 3 and 4 propose thermally conductive polysiloxane compositions containing aluminum nitride particles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6246986 [Patent Document 2] Patent No. 7039157 [Patent Document 3] Patent No. 7082563 [Patent Document 4] Patent No. 7205554 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional thermally conductive compositions and thermally conductive sheets using them have problems with moldability due to the increased plasticity of the composition when the thermal conductivity is increased, and the compressive load value of the cured thermally conductive sheet also increases, leaving further improvements necessary.

[0005] In order to solve the above-mentioned problems of the prior art, the present invention provides a thermally conductive composition having high thermal conductivity and a low compressive load value, a thermally conductive sheet using the same, and a method for producing the same. [Means for solving the problem]

[0006] The thermally conductive composition of the present invention is a thermally conductive composition comprising a matrix resin (A) and thermally conductive inorganic particles (B), the matrix resin (A) comprises an addition-curable silicone polymer (A1) and a non-reactive silicone oil (A2); When the matrix resin (A) is taken as 100% by mass, the addition-curable silicone polymer (A1) is 30% by mass or more and less than 100% by mass, and the non-reactive silicone oil (A2) is more than 0% by mass and 60% by mass or less; The thermally conductive inorganic particles (B) contain the following B1, B2, and B3, and are contained in the following amounts relative to 100 parts by mass of the matrix resin (A), B1: 400 to 1,000 parts by mass of thermally conductive inorganic particles with a D50 (median diameter) of less than 10 μm B2: 400 to 1,000 parts by mass of thermally conductive inorganic particles with a D50 (median diameter) of 10 μm or more and less than 100 μm B3: 800 to 1,500 parts by mass of thermally conductive inorganic particles with a D50 (median diameter) of 100 μm or more the total of B1, B2 and B3 is 2000 to 3000 parts by mass relative to 100 parts by mass of the matrix resin (A), The thermally conductive composition has an instantaneous load value of 500 N or less when compressed 50% with a diameter of 28.6 mm and a thickness of 2 mm.

[0007] The thermally conductive sheet of the present invention is characterized in that the thermally conductive composition is formed into a sheet.

[0008] In the method for producing a thermally conductive sheet of the present invention, the thermally conductive composition is vacuum degassed, rolled, formed into a sheet, and then cured by heating to produce a thermally conductive sheet. [Effects of the Invention]

[0009] By using the above composition, the present invention can provide a thermally conductive composition having high thermal conductivity and a low compressive load value, a thermally conductive sheet using the same, and a method for producing the same. Specifically, the thermal conductivity of the thermally conductive composition is 8.5 W / mK or higher, and the instantaneous load value when the thermally conductive composition is compressed 50% to a diameter of 28.6 mm and a thickness of 2 mm is 500 N or lower. Furthermore, the method for producing a thermally conductive sheet of the present invention enables continuous sheet molding because the composition has low plasticity and good moldability. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a method of using a thermally conductive sheet according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic side cross-sectional view of a compression load measuring device used in one embodiment of the present invention. [Figure 3] 3A-B are schematic explanatory views showing a method for measuring the thermal conductivity of a sample in one embodiment of the present invention. [Figure 4] FIG. 4A is a schematic cross-sectional view showing an oil-bleed width measurement test in one embodiment of the present invention, and FIG. 4B is a schematic plan view showing the measurement of the oil-bleed width. [Figure 5] FIG. 5 is a scanning electron microscope (SEM, magnification: 5000 times) photograph of amorphous alumina (D50=0.3 μm) according to one embodiment of the present invention. [Figure 6] FIG. 6 is a scanning electron microscope (SEM, 100x magnification) photograph of spherical alumina (D50=120 μm) according to one embodiment of the present invention. [Figure 7] FIG. 7 is a scanning electron microscope (SEM, 500x magnification) photograph of amorphous aluminum nitride (D50=20 μm) according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention provides a conductive composition containing a matrix resin (A) and thermally conductive inorganic particles (B). The matrix resin (A) contains an addition-curable silicone polymer (A1) and a non-reactive silicone oil (A2). When the matrix resin (A) is taken as 100% by mass, the addition-curable silicone polymer (A1) is at least 30% by mass but less than 100% by mass, and the non-reactive silicone oil (A2) is more than 0% by mass but not more than 60% by mass. Preferably, the addition-curable silicone polymer (A1) is at least 32% by mass but not more than 90% by mass, and the non-reactive silicone oil (A2) is at least 10% by mass but not more than 68% by mass. More preferably, the addition-curable silicone polymer (A1) is at least 35% by mass but not more than 80% by mass, and the non-reactive silicone oil (A2) is at least 20% by mass but not more than 65% by mass. Even more preferably, the addition-curable silicone polymer (A1) is at least 38% by mass but not more than 70% by mass, and the non-reactive silicone oil (A2) is at least 30% by mass but not more than 62% by mass. By setting the content within the above range, it is possible to keep the compression load value low and also to reduce oil bleeding.If the content of the non-reactive silicone oil (A2) exceeds 60 mass %, oil bleeding increases, which is not preferable.

[0012] The thermally conductive inorganic particles (B) contain the following B1, B2, and B3, and are contained in the following amounts per 100 parts by mass of the matrix resin (A). B1: The amount of thermally conductive inorganic particles having a D50 (median diameter) of less than 10 μm is 400 to 1000 parts by mass, preferably 410 to 950 parts by mass, more preferably 420 to 900 parts by mass, and even more preferably 430 to 850 parts by mass. B2: The amount of thermally conductive inorganic particles having a D50 (median diameter) of 10 μm or more and less than 100 μm is 400 to 1000 parts by mass, preferably 420 to 950 parts by mass, more preferably 440 to 900 parts by mass, and even more preferably 460 to 800 parts by mass. B3: Thermally conductive inorganic particles having a D50 (median diameter) of 100 μm or more are 800 to 1500 parts by mass, preferably 820 to 1400 parts by mass, more preferably 840 to 1350 parts by mass, and even more preferably 860 to 1300 parts by mass. The total amount of B1, B2 and B3 is 2000 to 3000 parts by mass relative to 100 parts by mass of the matrix resin (A). In the present invention, the thermally conductive particles are a mixture of multiple types of inorganic particles with different average particle sizes. This allows smaller thermally conductive inorganic particles to be embedded between larger particles, resulting in a nearly close-packed state and increased thermal conductivity. Furthermore, the composition has low plasticity, resulting in a thermally conductive composition with good moldability. Furthermore, the thermally conductive composition has a low compressive load and is easier to handle than putty-like materials, resulting in a thermal interface material (TIM) heat dissipation sheet.

[0013] The instantaneous load value when the thermally conductive composition is compressed 50% to a diameter of 28.6 mm and a thickness of 2 mm is 500 N or less, preferably 100 to 500 N, more preferably 100 to 480 N, and even more preferably 100 to 450 N. This makes it easier to crush, reduces the physical load on the heat-generating element, and provides desirable physical properties for a heat-dissipating sheet: TIM (Thermal Interface Material).

[0014] The thermal conductivity of the thermally conductive composition is preferably 8.5 W / m·K or more, more preferably 8.5 to 20 W / m·K, and even more preferably 9 to 15 W / m·K. This provides high thermal conductivity and makes the composition suitable as a heat dissipation sheet: TIM (Thermal Interface Material).

[0015] When the thermally conductive composition is sandwiched between a glass plate and a medicine wrapping paper to a size of 25 mm length, 25 mm width, and 2 mm thickness, compressed to a compression ratio of 50%, and held at 125°C for 72 hours, the oil-bleed width is preferably 10 mm or less. The oil-bleed width is more preferably 8 mm or less, and even more preferably 6 mm or less. This allows oil-bleed to be kept low.

[0016] The plasticity of the thermally conductive composition after degassing before curing is preferably 65 or less, more preferably 64 or less, and even more preferably 63 or less. This results in a thermally conductive composition with low plasticity and excellent moldability. Plasticity is measured using a Wallace plastometer in accordance with JIS K 6300-3 and ISO 2007:1991 at a measurement temperature of 25°C. The plasticity is calculated by dividing the thickness (t) of a sample compressed between two metal plates at a constant load (100 N) for a constant time (15 seconds) by the thickness (t0) before compression (P0 = t / t0 × 100). A smaller P0 indicates greater flexibility.

[0017] The thermally conductive inorganic particles B1, B2, and B3 are preferably at least one selected from the group consisting of amorphous alumina, spherical alumina, and amorphous aluminum nitride. Using these particles increases thermal conductivity. "Amorphous" refers to irregularly shaped particles. Figure 5 shows a scanning electron microscope (SEM, magnification 5000x) photograph of amorphous alumina (D50 = 0.3 μm), Figure 6 shows a scanning electron microscope (SEM, magnification 100x) photograph of spherical alumina (D50 = 120 μm), and Figure 7 shows a scanning electron microscope (SEM, magnification 500x) photograph of amorphous aluminum nitride (D50 = 20 μm).

[0018] The matrix resin (A) preferably further contains a silane coupling agent. The silane coupling agent is preferably added in an amount of 0.1 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, per 100 parts by mass of the matrix resin. The silane coupling agent can produce a thermally conductive composition with a low compressive load value, and also coats the surface of the thermally conductive particles (surface treatment), making them easier to fill into the matrix resin (plasticizer function), preventing the curing catalyst from being adsorbed onto the thermally conductive particles and preventing curing inhibition. This is useful for storage stability. The silane coupling agent is R(CH3) a Si(OR') 4-a(R is an unsubstituted or substituted organic group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) or a partial hydrolyzate thereof. a Si(OR') 4-a Examples of alkoxysilane compounds (hereinafter simply referred to as "silanes") represented by the formula (R is an unsubstituted or substituted organic group having 1 to 20 carbon atoms, R' is an alkyl group having 1 to 4 carbon atoms, and a is 0 or 1) include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, and octadecyltriethoxysilane. These silane compounds can be used alone or in combination.

[0019] The thermally conductive composition of the present invention is molded into a sheet to provide a thermally conductive sheet, which is highly versatile and suitable as a TIM. The thickness of the thermally conductive sheet is preferably in the range of 0.2 to 10 mm.

[0020] In the method for producing a thermally conductive sheet of the present invention, the thermally conductive composition is vacuum degassed, rolled, formed into a sheet, and then heat cured to form a thermally conductive sheet. In the vacuum degassing, the thermally conductive composition (compound) is decompressed to a pressure of -0.08 to -0.1 Pa and left for about 5 to 10 minutes to degas. Rolling can be performed by roll rolling or press working, but roll rolling is preferred because it allows for continuous production.

[0021] The thermally conductive composition preferably has a breakdown voltage (JIS K6249) of 7 to 16 kV / mm, which allows the thermally conductive sheet to have high electrical insulation.

[0022] The volume resistivity (JIS K6249) of the thermally conductive composition is 10 10 ~10 14 It is preferable that the resistance is Ω·cm, which allows the sheet to have high electrical insulation and thermal conductivity.

[0023] As an example of the present invention, in the case of an addition reaction type silicone composition, a compound having the following composition is preferred. A Matrix resin The matrix resin contains the following (a1) and (a2): (a1) Base polymer component: a linear organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in each molecule (a2) Crosslinking component: an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in an amount of less than 1 mole per mole of silicon-bonded alkenyl groups in component A Non-reactive silicone oils have no reactive groups other than the components (a1) and (a2). Non-reactive silicone oils are also called unreacted silicone oils. Examples include dialkylpolysiloxanes such as dimethylpolysiloxane, and diphenylpolysiloxane. C. Platinum-based metal catalyst: Amount of 0.01 to 1000 ppm by mass relative to the matrix resin D. Other additives: silane coupling agents, curing retarders, colorants, etc.; optional amounts

[0024] Each component will be described below. (1) Base polymer component (component a1) The base polymer component is an organopolysiloxane containing two or more silicon-bonded alkenyl groups per molecule, and this organopolysiloxane containing two or more alkenyl groups is the main component (base polymer component) in the silicone rubber composition of the present invention. This organopolysiloxane contains two silicon-bonded alkenyl groups per molecule, such as vinyl or allyl groups, each having 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms. From the standpoint of workability and curability, the viscosity at 25°C is preferably 10 to 1,000,000 mPa·s, and more preferably 100 to 100,000 mPa·s. Specifically, an organopolysiloxane is used, which contains two or more alkenyl groups per molecule, each of which is represented by the following general formula (Chemical Formula 1), and which is bonded to the silicon atom at the molecular chain end. The side chains are linear organopolysiloxanes blocked with alkyl groups. From the viewpoint of workability and curability, a viscosity of 10 to 1,000,000 mPa·s at 25°C is desirable. Note that this linear organopolysiloxane may also contain a small amount of branched structure (trifunctional siloxane units) in the molecular chain.

[0025] [ka]

[0026] In the formula, R 1 are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds, and R 2 is an alkenyl group, and k is 0 or a positive integer. 1Examples of unsubstituted or substituted monovalent hydrocarbon groups that do not have an aliphatic unsaturated bond include those having 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, and decyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, or chlorine, or with cyano groups, such as halogen-substituted alkyl groups such as chloromethyl, chloropropyl, bromoethyl, and trifluoropropyl; and cyanoethyl groups. 2 The alkenyl group preferably has 2 to 6 carbon atoms, particularly 2 to 3 carbon atoms, and specific examples include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, hexenyl, and cyclohexenyl groups, with vinyl being preferred. In general formula (1), k is generally 0 or a positive integer satisfying 0≦k≦10000, preferably 5≦k≦2000, and more preferably 10≦k≦1200. The organopolysiloxane of component a1 may be an organopolysiloxane having three or more, typically 3 to 30, and preferably about 3 to 20, alkenyl groups, such as vinyl groups or allyl groups, each bonded to a silicon atom and having 2 to 8, and particularly 2 to 6, carbon atoms. The molecular structure may be linear, cyclic, branched, or three-dimensional network. A preferred example is a linear organopolysiloxane whose main chain is composed of repeating diorganosiloxane units and whose molecular chain is terminally blocked with triorganosiloxy groups, and whose viscosity at 25°C is 10 to 1,000,000 mPa·s, and particularly 100 to 100,000 mPa·s.

[0027] The alkenyl group may be bonded to any part of the molecule. For example, it may be bonded to a silicon atom at either the molecular chain terminal or a non-terminal (in the middle of the molecular chain) location. Among these, linear organopolysiloxanes are those represented by the following general formula (Chemical Formula 2): 1 to 3 alkenyl groups on each of the silicon atoms at both molecular chain terminals (however, if the total number of alkenyl groups bonded to the terminal silicon atoms at both molecular chain terminals is less than three, then those having at least one alkenyl group bonded to a non-terminal (in the middle of the molecular chain) silicon atom (for example, as a substituent in a diorganosiloxane unit) are preferred from the viewpoints of workability and curability, as mentioned above. These linear organopolysiloxanes may also contain a small amount of branched structures (trifunctional siloxane units) in the molecular chain.

[0028] [ka]

[0029] In the formula, R 3 are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and at least one is an alkenyl group. 4 are the same or different unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds, and R 5 is an alkenyl group, and l and m are 0 or positive integers. 3As the monovalent hydrocarbon group, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferred. Specifically, alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc., aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, etc., aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, etc., alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group, etc., and those in which a part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine, bromine, chlorine, etc., cyano group, etc., for example, halogen-substituted alkyl groups such as chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, etc., and cyanoethyl group, etc. can be mentioned. Also, R 4 As the monovalent hydrocarbon group of, those having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms are preferred. The same examples as those of the above R 1 can be exemplified, but alkenyl groups are not included. As the alkenyl group of R 5 , for example, those having 2 to 6 carbon atoms, particularly 2 to 3 carbon atoms are preferred. Specifically, the same ones as R of the above formula (Chemical Formula 1) 2 are exemplified, and preferably it is a vinyl group. l and m are generally 0 or positive integers satisfying 0 < l + m ≦ 10000, preferably 5 ≦ l + m ≦ 2000, more preferably 10 ≦ l + m ≦ 1200, and are integers satisfying 0 < l / (l + m) ≦ 0.2, preferably 0.0011 ≦ l / (l + m) ≦ 0.1.

[0030] (2) Crosslinking component (a2 component) The organohydrogenpolysiloxane of component a2 of the present invention acts as a crosslinking agent, forming a cured product through an addition reaction (hydrosilylation) between the SiH groups in this component and the alkenyl groups in component A. Any organohydrogenpolysiloxane may be used as long as it has two or more hydrogen atoms bonded to silicon atoms (i.e., SiH groups) per molecule, and the molecular structure of this organohydrogenpolysiloxane may be linear, cyclic, branched, or a three-dimensional network structure, but those with a number of silicon atoms per molecule (i.e., degree of polymerization) of 2 to 1000, and particularly about 2 to 300, can be used.

[0031] The position of the silicon atom to which the hydrogen atom is bonded is not particularly limited, and it may be at the end of the molecular chain or at a non-end of the molecular chain (in the middle of the molecular chain). In addition, examples of organic groups bonded to silicon atoms other than hydrogen atoms include R 1 and unsubstituted or substituted monovalent hydrocarbon groups having no aliphatic unsaturated bonds, similar to those shown above.

[0032] Examples of organohydrogenpolysiloxanes of component a2 include those with the following structures: [ka]

[0033] In the above formula, R 6 are the same or different alkyl groups, phenyl groups, epoxy groups, acryloyl groups, methacryloyl groups, alkoxy groups, or hydrogen atoms, and at least two of them are hydrogen atoms. L is an integer of 0 to 1,000, particularly an integer of 0 to 300, and M is an integer of 1 to 200.

[0034] (3) Catalyst component (C component) The catalyst component of component C can be a catalyst used in hydrosilylation reactions. Examples include platinum black, platinic chloride, chloroplatinic acid, reaction products of chloroplatinic acid with monohydric alcohols, complexes of chloroplatinic acid with olefins or vinylsiloxanes, platinum-based catalysts such as platinum bisacetoacetate, palladium-based catalysts, and rhodium-based catalysts. Two-component room-temperature-curing silicone polymers contain a platinum-group metal catalyst, but the use of an additional platinum-group metal catalyst is to control the curing speed.

[0035] (4) Other additives The composition of the present invention may contain other components as needed. For example, heat resistance improvers such as red iron oxide, titanium oxide, and cerium oxide, flame retardant assistants, and cure retarders may be added. Organic or inorganic pigments may be added for coloring or toning purposes. The above-mentioned silane coupling agents may also be added.

[0036] The following description will be made with reference to the drawings. In the following drawings, the same reference numerals indicate the same parts. FIG. 1 is a schematic cross-sectional view of a heat dissipation structure 1 incorporating thermally conductive sheets 2a and 2b according to one embodiment of the present invention. The thermally conductive sheet 2b dissipates heat generated by an electronic component 4 such as a semiconductor device. The thermally conductive sheet 2b is fixed to a main surface 3a of the heat spreader 3 facing the electronic component 4, and is sandwiched between the electronic component 4 and the heat spreader 3. The thermally conductive sheet 2a is sandwiched between the heat spreader 3 and a heat sink 6. The thermally conductive sheets 2a and 2b, together with the heat spreader 3, constitute a heat dissipation member that dissipates heat from the electronic component 4. The heat spreader 3 is formed, for example, in the shape of a rectangular plate, and has a main surface 3a facing the electronic component 4 and a side wall 3b extending along the outer periphery of the main surface 3a. The heat spreader 3 has a thermally conductive sheet 2b on a main surface 3a surrounded by side walls 3b, and a heat sink 6 on another surface 3c opposite to the main surface 2a, with the thermally conductive sheet 2a interposed therebetween. The electronic component 4 is, for example, a semiconductor element such as a BGA, and is mounted on a wiring board 5. [Example]

[0037] The present invention will be described below using examples, but is not limited to these examples. Various parameters were measured by the methods described below.

[0038] <50% compression load value> The compressive load was measured in accordance with ASTM D575-91:2012. Figure 2 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 7 includes a sample stage 8 and a load cell 12. A thermally conductive sheet sample 10 is sandwiched between aluminum plates 9 and 11, mounted as shown in Figure 2, and compressed to a specified thickness using the load cell 12. The maximum load value when the thickness is compressed by 50% and the load value after maintaining this compression for one minute are recorded. Measurement conditions Sample: circular (diameter 28.6 mm, thickness 2 mm) Compression ratio: 50% Aluminum plate size: circular (diameter 28.6 mm) (compression surface) Compression speed: 5mm / min Compression method: TRIGGER method (measurement starts when a load of 2N is detected) Measuring device: Aiko Engineering, MODEL-1311NW (load cell 2kN) <Thermal conductivity> The thermal conductivity of the thermally conductive sheet was measured using a hot disk (compliant with ISO 22007-2:2008). As shown in Figure 3A, this thermal conductivity measuring device 13 sandwiches a polyimide film sensor 14 between two thermally conductive sheet samples 15a and 15b. A constant power is applied to the sensor 14 to generate heat, and the thermal characteristics are analyzed from the temperature rise of the sensor 14. The sensor 14 has a 7 mm diameter tip 16 and, as shown in Figure 3B, has a double spiral electrode structure with an applied current electrode 17 and a resistance electrode (temperature measurement electrode) 18 located at the bottom. The thermal conductivity was calculated using the following equation (Equation 1).

number

[0039] (Examples 1 to 10, Comparative Examples 1 to 5) 1.Material composition (1) Polyorganosiloxane (Component A1) A commercially available two-component room-temperature curing silicone polymer (silicone component) containing polyorganosiloxane was used. One component (component A) contains the base polymer component and a platinum group metal catalyst, while the other component (component B) contains the base polymer component and a crosslinker component, organohydrogenpolysiloxane. The mass ratio of components A and B was A:B = 100:100. (2) Non-reactive silicone oil (component A2) As the non-reactive silicone oil (A2), commercially available dimethyl silicone oil (viscosity: 100 mm 2 / s) was used. (3) Thermally conductive particles (component B) The thermally conductive particles used were those listed in Tables 1 and 2. The average particle size is the D50 (median diameter) of the cumulative particle size distribution on a volume basis, as determined by measuring particle size distribution using a laser diffraction light scattering method. An example of the measuring device used is the LA-950S2 laser diffraction / scattering particle distribution analyzer manufactured by Horiba, Ltd. Furthermore, AlN in the tables is an abbreviation for aluminum nitride. (4)Platinum group metal catalyst A platinum-vinyldisiloxane complex was used as the additional platinum group metal catalyst. As described above, the two-component room temperature curing silicone polymer (silicone component) contained a platinum group metal catalyst. When preparing the silicone composition of each example, an additional platinum group metal catalyst was added to ensure that the polyorganosiloxane was sufficiently cured. (5) Plasticizer Decyltrimethoxysilane was used as the silane coupling agent.

[0040] 2. Compound The amounts of each material shown in Tables 1 and 2 were weighed out and placed in a mixer to form a compound. In Tables 1 and 2, the amount of each material is listed in parts by mass, assuming 100 parts by mass (100 g) of the silicone component (two-component room-temperature-curing silicone polymer). The compound was degassed for 5 minutes under a reduced pressure of -0.1 Pa.

[0041] 3. Sheet molding The compound was sandwiched between release-treated polyethylene terephthalate (PET) films, rolled using a constant speed roll into a 2.0 mm thick sheet, and then heated and cured for 10 minutes at 100°C to form a thermally conductive silicone rubber sheet. If molding was possible under the above conditions, the product was judged as "possible," and if not, it was judged as "NG."

[0042] [Table 1] [Table 2] [Table 3] [Table 4]

[0043] The following can be seen from Tables 1 to 4. (1) Examples 1 to 10 had high thermal conductivity, low compressive load value, and low plasticity. In addition, oil bleeding was also small. (2) In Comparative Example 1, the non-reactive silicone oil (A2) was added in an amount exceeding the upper limit, so that although the compressive load value and plasticity were low, oil bleeding increased, which was not preferable. (3) Comparative Example 2 was undesirable because it contained only the addition-curable silicone polymer (A1), resulting in high compressive load values ​​and plasticity. (4) In Comparative Example 3, when the thermally conductive inorganic particles (B3) having a D50 (median diameter) of 100 μm or more exceeded the upper limit, the compressive load value and plasticity increased, which was not preferable. (5) In Comparative Example 4, when the amount of the thermally conductive inorganic particles (B1) having a D50 (median diameter) of less than 10 μm was below the lower limit, kneading was not possible. (6) In Comparative Example 5, when the thermally conductive inorganic particles (B2) having a D50 (median diameter) of 10 μm or more and less than 100 μm fell below the lower limit, the plasticity was low but the compressive load value increased, which was undesirable. [Industrial Applicability]

[0044] The thermally conductive composition and thermally conductive sheet of the present invention are suitable as a thermal interface material (TIM) that is placed between a heat-generating portion of an electric or electronic part and a heat sink. [Explanation of symbols]

[0045] 1 Heat dissipation structure 2a, 2b Thermally conductive sheet 3 Heat spreader 4. Electronic Components 5. Wiring board 6 Heatsink 7. Compression load measuring device 8 Sample stage 9,11 Aluminum plate 10, 15a, 15b Thermally conductive sheet sample 12 load cells 13 Thermal conductivity measuring device 14 Polyimide film sensor 16 Sensor tip 17 Electrode for applied current 18 Resistance electrode (temperature measurement electrode) 21 Oil bleed width measurement test device 22 Thermally conductive hardened sheet samples 23a,23b Medicine wrapping paper 24 Aluminum plate 25 Glass Plate

Claims

1. A thermally conductive composition comprising a matrix resin (A) and thermally conductive inorganic particles (B), the matrix resin (A) comprises an addition-curable silicone polymer (A1) and a non-reactive silicone oil (A2); When the matrix resin (A) is taken as 100% by mass, the addition-curable silicone polymer (A1) is 30% by mass or more and less than 100% by mass, and the non-reactive silicone oil (A2) is more than 0% by mass and 60% by mass or less. The thermally conductive inorganic particles (B) contain the following B1, B2, and B3, and are contained in the following amounts relative to 100 parts by mass of the matrix resin (A), B1: 400 to 1,000 parts by mass of thermally conductive inorganic particles having a D50 (median diameter) of less than 10 μm B2: 400 to 1,000 parts by mass of thermally conductive inorganic particles having a D50 (median diameter) of 10 μm or more and less than 100 μm B3: 800 to 1,500 parts by mass of thermally conductive inorganic particles having a D50 (median diameter) of 100 μm or more the total amount of B1, B2, and B3 is 2,000 to 3,000 parts by mass relative to 100 parts by mass of the matrix resin (A); A thermally conductive composition characterized in that the instantaneous load value when compressed 50% to a diameter of 28.6 mm and a thickness of 2 mm is 500 N or less.

2. The thermally conductive composition according to claim 1 , wherein the thermal conductivity of the thermally conductive composition is 8.5 W / mK or more.

3. 2. The thermally conductive composition according to claim 1, wherein the thermally conductive composition has a length of 25 mm, a width of 25 mm and a thickness of 2 mm, is sandwiched between a glass plate and a medicine wrapping paper at a compression ratio of 50%, and is kept at 125°C for 72 hours. When the thermally conductive composition is then compressed to a length of 25 mm, a width of 25 mm and a thickness of 2 mm, the oil-bleed width is 10 mm or less.

4. 2. The thermally conductive composition according to claim 1, wherein the thermally conductive composition has a plasticity of 65 or less after degassing before curing.

5. 2. The thermally conductive composition according to claim 1, wherein the thermally conductive inorganic particles B1, B2, and B3 are at least one selected from the group consisting of amorphous alumina, spherical alumina, and amorphous aluminum nitride.

6. The thermally conductive composition according to claim 1 , wherein the matrix resin (A) further contains a silane coupling agent.

7. A thermally conductive sheet, wherein the thermally conductive composition according to any one of claims 1 to 6 is formed into a sheet.

8. 8. The thermally conductive sheet according to claim 7, wherein the thickness of the thermally conductive sheet is in the range of 0.2 to 10 mm.

9. A method for producing a thermally conductive sheet, comprising vacuum degassing the thermally conductive composition according to any one of claims 1 to 6, rolling it, forming it into a sheet, and then heat-curing it to produce a thermally conductive sheet.

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