JP2024106910A - Resin composition, heat dissipation member, and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition which has a high coefficient of thermal conductivity, has small stress in compression, and can suppress damage of a member.

SOLUTION: A resin composition contains a resin and an inorganic filler, wherein the inorganic filler contains a first inorganic filler and a second inorganic filler having respective Vickers hardness values different from each other by 20 GPa or more, the Vickers hardness value of the first inorganic filler is larger than the Vickers hardness value of the second inorganic filler, an average particle diameter (α) of the first inorganic filler is larger than an average particle diameter (β) of the second inorganic filler, a ratio [(B)/(A)] of a volume filling rate (B) of the second inorganic filler to a volume filling rate (A) of the first inorganic filler is 0.08 or more and 0.42 or less, and a content of the total inorganic filler is 80 vol.% or more.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a resin composition, a heat dissipation member formed from the resin composition, and an electronic device equipped with the heat dissipation member.

In recent years, as electrical equipment becomes smaller and more powerful, there is a demand for heat dissipation materials that maintain electrical insulation and efficiently dissipate heat generated during operation. A known heat dissipation material is a thermally conductive composition in which a thermally conductive filler is filled into a resin. In addition, a technique for using multiple different thermally conductive fillers in combination is also known from the perspective of improving thermal conductivity.

Patent Document 1 discloses an invention relating to a thermally conductive silicone grease composition that contains, in a specific mixing ratio, a thermally conductive inorganic filler having a Mohs hardness of 6 or more and an average particle size of 5 to 20 μm, and a thermally conductive inorganic filler having a Mohs hardness of 5 or less and an average particle size of 0.5 to 5 μm. It also describes that this thermally conductive silicone grease composition has excellent thermal conductivity as well as excellent resistance to shear.
Patent Document 2 discloses an invention relating to a thermally conductive silicone composition characterized by having a silicone resin, a first filler of diamond, a second filler of zinc oxide, and a dispersant, and states that the thermally conductive silicone composition can efficiently conduct heat generated by electronic components to a heat sink for heat dissipation.

JP 2010-242022 A JP 2002-030217 A

Among the thermally conductive compositions that have been conventionally used, some have high thermal conductivity, but in order to further increase the thermal conductivity, it is generally necessary to highly fill the resin with a thermally conductive filler.
However, a resin composition containing a large amount of a thermally conductive filler has a problem that stress is high when compressed. More specifically, when mounting a component (e.g., a semiconductor chip, etc.), in a process of placing the component on the resin composition and compressing the resin composition, the stress of the resin composition becomes high, resulting in a problem that the component is damaged.
Therefore, an object of the present invention is to provide a resin composition that has high thermal conductivity, is subject to small stress when compressed, and is capable of suppressing damage to members.

As a result of extensive research to achieve the above-mentioned object, the inventors discovered that the above-mentioned problem can be solved by a resin composition containing a first inorganic filler and a second inorganic filler, the Vickers hardness, average particle size, and volume filling rate of which have a specific relationship, and thus completed the present invention.
That is, the present invention relates to the following [1] to [8].

[1] A resin composition containing a resin and an inorganic filler, the inorganic filler comprising a first inorganic filler and a second inorganic filler having Vickers hardnesses differing by 20 GPa or more, the Vickers hardness of the first inorganic filler being greater than the Vickers hardness of the second inorganic filler, the average particle size (α) of the first inorganic filler being greater than the average particle size (β) of the second inorganic filler, the ratio [(B)/(A)] of the volumetric filling rate (B) of the second inorganic filler to the volumetric filling rate (A) of the first inorganic filler being 0.08 or more and 0.42 or less, and the content of the total inorganic filler being 80 volume% or more.
[2] The resin composition described in [1] above, wherein the thermal conductivity of the first inorganic filler is higher than the thermal conductivity of the second inorganic filler.
[3] The resin composition according to [1] or [2] above, wherein the first inorganic filler is diamond or cubic boron nitride.
[4] The resin composition according to any one of [1] to [3] above, wherein the content of the first inorganic filler is 20% by volume or more and 80% by volume or less based on the total amount of the resin composition.
[5] The resin composition according to any one of the above [1] to [4], further comprising a dispersant, and the content of the dispersant is 5 to 40 mass% based on the total amount of the resin composition excluding the inorganic filler.
[6] The resin composition according to any one of [1] to [5] above, having a viscosity at 25°C of 400 mPa·s or less.
[7] A heat dissipation member formed from the resin composition according to any one of [1] to [6] above.
[8] An electronic device comprising: an electronic component; and the heat dissipation member according to [7] above, disposed on the electronic component.

The present invention provides a resin composition that has high thermal conductivity, low stress when compressed, and can suppress damage to components.

The resin composition of the present invention contains a resin and an inorganic filler, and the inorganic filler includes a first inorganic filler and a second inorganic filler whose Vickers hardness differs by 20 GPa or more, and the Vickers hardness of the first inorganic filler is greater than the Vickers hardness of the second inorganic filler. The average particle size (α) of the first inorganic filler is greater than the average particle size (β) of the second inorganic filler, the ratio [(B)/(A)] of the volumetric filling rate (B) of the second inorganic filler to the volumetric filling rate (A) of the first inorganic filler is 0.08 or more and 0.42 or less, and the content of all inorganic fillers is 80 volume% or more.

The resin composition of the present invention has an inorganic filler content of 80% or more by volume, is highly filled with inorganic filler, and has high thermal conductivity. In addition, despite being highly filled with inorganic filler, the resin composition of the present invention has low stress upon compression, and can suppress damage to a member compressing the resin composition.
The reason for this is presumed to be as follows. The resin composition of the present invention contains a first inorganic filler and a second inorganic filler. The first inorganic filler has a Vickers hardness 20 GPa or more higher than that of the second inorganic filler, a larger average particle size than that of the second inorganic filler, and a larger filling amount than that of the second inorganic filler. That is, the resin composition of the present invention contains a first inorganic filler having a high hardness and a large particle size, and a second inorganic filler having a low hardness and a small particle size, and the filling amount of the first inorganic filler is greater. For this reason, when the resin composition is compressed, a part of the second inorganic filler is scraped or crushed by the first inorganic filler. It is presumed that this relieves the stress during compression, reduces the stress applied to the member, and suppresses damage to the member.

<Inorganic filler>
(Vickers hardness)
The resin composition of the present invention includes a first inorganic filler and a second inorganic filler, and includes the first inorganic filler and the second inorganic filler having a Vickers hardness difference of 20 GPa or more, and the Vickers hardness of the first inorganic filler is greater than the Vickers hardness of the second inorganic filler. That is, the difference in Vickers hardness between the first inorganic filler and the second inorganic filler is 20 GPa or more. This can reduce the stress when compressing the resin composition, making it easier to suppress damage to the member compressing the resin composition.
From the viewpoint of reducing stress during compression, the difference in Vickers hardness between the first inorganic filler and the second inorganic filler is preferably 30 GPa or more, more preferably 50 GPa or more, and even more preferably 60 GPa or more. The upper limit of the difference in Vickers hardness between the first inorganic filler and the second inorganic filler is not particularly limited, but is, for example, 100 GPa.

The Vickers hardness of the first inorganic filler is not particularly limited as long as the difference in Vickers hardness between the first inorganic filler and the second inorganic filler is within the above range, for example, 30 GPa or more and 130 GPa or less, preferably 40 GPa or more and 100 GPa or less, and more preferably 50 GPa or more and 90 GPa or less.
The Vickers hardness of the second inorganic filler is not particularly limited as long as the difference in Vickers hardness between the first inorganic filler and the second inorganic filler is within the above range, for example, 1 GPa or more and 60 GPa or less, preferably 5 GPa or more and 40 GPa or less, and more preferably 10 GPa or more and 30 GPa or less.
The Vickers hardness can be measured in accordance with JIS Z 2244. Specifically, it means the quotient obtained by dividing the load F (N) applied when a pyramidal indenter made of regular square pyramid diamond with a facing angle of 136 degrees is pressed into the surface of a material to make an indentation on the test surface by the surface area calculated from the diagonal length d (mm) of the indentation.

(Average particle size)
In the present invention, the average particle size (α) of the first inorganic filler is larger than the average particle size (β) of the second inorganic filler, whereby the stress when compressing the resin composition can be reduced, and damage to the member compressing the resin composition can be easily suppressed.
From the viewpoint of reducing stress during compression, the difference in average particle size between the first inorganic filler and the second inorganic filler is preferably 10 μm or more and 200 μm or less, more preferably 30 μm or more and 150 μm or less, even more preferably 40 μm or more and 130 μm or less, and even more preferably 50 μm or more and 70 μm or less.

The average particle size (α) of the first inorganic filler is not particularly limited as long as it is larger than the average particle size (β) of the second inorganic filler, and is, for example, 10 μm or more and 250 μm or less, preferably 20 μm or more and 200 μm or less, and more preferably 30 μm or more and 180 μm or less.
The average particle size (β) of the second inorganic filler is not particularly limited as long as it is smaller than the average particle size (α) of the first inorganic filler, and is, for example, 0.1 μm or more and 50 μm or less, preferably 0.2 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less.
In this specification, the average particle size of the inorganic filler can be determined by measuring the 50% particle size (D50) in the cumulative particle size distribution based on the volume of primary particles. The cumulative particle size distribution based on the volume is determined using a laser diffraction/scattering type particle size distribution measuring device. Examples of the laser diffraction/scattering type particle size distribution measuring device include "MT3300EXII" manufactured by Microtrac.

(Volume filling rate)
In the resin composition of the present invention, the ratio of the volume filling rate (B) of the second inorganic filler to the volume filling rate (A) of the first inorganic filler [(B)/(A)] is 0.08 to 0.42. By setting the volume filling rate ratio in such a range, the stress when compressing the resin composition can be reduced, and damage to the member compressing the resin composition can be easily suppressed.
From the viewpoint of reducing stress during compression, the volume filling rate ratio [(B)/(A)] is 0.09 or more and 0.3 or less, more preferably 0.09 or more and 0.2 or less, and even more preferably 0.09 or more and 0.15 or less.

The volume filling rate (content) of the first inorganic filler in the resin composition of the present invention is not particularly limited, but is preferably 20 vol.% or more and 90 vol.% or less, more preferably 20 vol.% or more and 85 vol.% or less, even more preferably 20 vol.% or more and 80 vol.% or less, even more preferably 30 vol.% or more and 80 vol.% or less, and even more preferably 40 vol.% or more and 80 vol.% or less.
In addition, the first inorganic filler may be a mixture of two or more inorganic fillers having different average particle sizes, and the volume filling rate of the inorganic filler having the largest average particle size among the first inorganic fillers in the resin composition is preferably 20 vol. % or more and 80 vol. % or less, and more preferably 35 vol. % or more and 75 vol. % or less.
The volumetric filling rate of the second inorganic filler in the resin composition of the present invention is not particularly limited, but is preferably 1 volume % or more and 40 volume % or less, more preferably 3 volume % or more and 35 volume % or less, and even more preferably 5 volume % or more and 30 volume % or less.
The resin composition of the present invention may contain an inorganic filler other than the first inorganic filler and the second inorganic filler. The total amount of the first inorganic filler and the second inorganic filler in the resin composition of the present invention is preferably 25% by volume or more, more preferably 50% by volume or more, and even more preferably 90% by volume or more.

The total inorganic filler content in the resin composition of the present invention is 80% by volume or more. In this way, the high content of inorganic filler increases the thermal conductivity of the resin composition. Furthermore, the high content of inorganic filler makes it easier for hard and large particles to contact with soft and small particles, and the effect of relaxing stress during compression is also enhanced.
The total content of inorganic fillers in the resin composition is preferably 83 vol% or more, more preferably 85 vol% or more, and preferably 95 vol% or less, preferably 90 vol% or less.

(Thermal Conductivity)
The first inorganic filler preferably has a higher thermal conductivity than the second inorganic filler. Since the first inorganic filler has a larger average particle size and a larger content than the second inorganic filler, increasing the thermal conductivity of the first inorganic filler improves the thermal conductivity of the resin composition and enhances the heat dissipation.
The difference between the thermal conductivity of the first inorganic filler and the thermal conductivity of the second inorganic filler is preferably 10 W/mK or more, more preferably 100 W/mK or more, even more preferably 500 W/mK or more, and preferably 4000 W/mK or less.

The thermal conductivity of the first inorganic filler is preferably 10 W/mK or more and 4000 W/mK or less, more preferably 100 W/mK or more and 3500 W/mK or less, and further preferably 500 W/mK or more and 3000 W/mK or less.
The thermal conductivity of the second inorganic filler is preferably 10 W/mK or more and 1000 W/mK or less, more preferably 15 W/mK or more and 700 W/mK or less, and further preferably 20 W/mK or more and 500 W/mK or less.
The thermal conductivity can be measured, for example, by a periodic heating thermoreflectance method using a thermal microscope manufactured by Bethel Corporation on a cross section of the inorganic filler cut with a cross section polisher.

(Types of inorganic fillers)
The type of inorganic filler is not particularly limited, but examples thereof include oxides, nitrides, carbides, carbon-based materials, and metal hydroxides.
Examples of the oxide include metal oxides such as iron oxide, zinc oxide, alumina, magnesium oxide, titanium oxide, cerium oxide, and zirconium oxide, and oxides other than metal oxides such as silicon oxide (silica).
Examples of the nitride include metal nitrides such as aluminum nitride, gallium nitride, chromium nitride, tungsten nitride, magnesium nitride, molybdenum nitride, and lithium nitride, and nitrides other than metal nitrides such as silicon nitride and boron nitride.
Examples of the carbide include metal carbides such as aluminum carbide, titanium carbide, and tungsten carbide, and carbides other than metal carbides such as silicon carbide and boron carbide.
Examples of carbon-based materials include carbon black, graphite, graphene, fullerene, carbon nanotubes, carbon nanofibers, and diamond.
Examples of metal hydroxides include aluminum hydroxide, calcium hydroxide, and magnesium hydroxide.

The types of the first inorganic filler and the second inorganic filler are not particularly limited, and can be appropriately selected from those described above, for example, so as to satisfy the predetermined requirements of the present invention.
Among the above, the first inorganic filler is preferably diamond or cubic boron nitride, and more preferably diamond. These inorganic fillers have high Vickers hardness and high thermal conductivity, so they are preferred as the first inorganic filler. The first inorganic filler may be used alone or in combination with a plurality of types.
The second inorganic filler is preferably alumina, aluminum nitride, magnesium oxide, boron nitride other than cubic boron nitride, or zinc oxide. Only one type of the second inorganic filler may be used, or multiple types may be used in combination.

<Resin>
The resin composition of the present invention contains a resin. The resin is a resin component that holds an inorganic filler, and is a matrix resin. The resin may be a curable resin or a non-curable resin such as a thermoplastic resin. It may also be an elastomer resin. The curable resin may be any of moisture curable, thermosetting, and photocurable. The resin is preferably a liquid component. The resin of the liquid component may be one that becomes solid when cured, or may be non-curable and remain liquid. The liquid component is a component that is liquid at room temperature (25° C.) and normal pressure (1 atm).

The curable resin may be either a one-component curing type or a two-component curing type. In the two-component curing type, a first component containing a base agent and a second component containing a curing agent are mixed together for use. In the two-component curing type, the first component and the second component are mixed together and cured, for example, at room temperature.
In the two-component curing type, the first component may be the resin composition of the present invention, the second component may be the resin composition of the present invention, or the first and second components may be mixed to form the resin composition of the present invention. However, it is preferable that both the first and second components are the resin composition of the present invention, and that the resulting mixture is also the resin composition of the present invention.

Specific examples of the resin include silicone resin, epoxy resin, acrylic resin, urethane resin, phenol resin, unsaturated polyester resin, polyimide resin, polypropylene resin, polyethylene resin, poly(1-)butene resin, polypentene resin and other polyolefin resins, polyethylene terephthalate and other polyester resins, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, ethylene vinyl acetate copolymer (EVA), polyamide resin, polyvinyl chloride resin (PVC), and the like.
The resin may be an elastomer resin, and specific examples thereof include acrylonitrile butadiene rubber, ethylene-propylene-diene rubber, ethylene-propylene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, polyester-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, styrene-based thermoplastic elastomer, etc. The elastomer resin may be in a liquid state or a solid state.
The resins may be used alone or in combination of two or more.
Of the above, the resin is preferably at least one selected from a silicone resin, an epoxy resin, an acrylic resin, a polybutadiene rubber, and a polyester resin, more preferably at least one selected from a silicone resin, an epoxy resin, and an acrylic resin, and even more preferably a silicone resin.

(Silicone resin)
Specific examples of silicone resins include curable silicone resins, which may be either condensation curable silicone resins or addition reaction curable silicone resins, with addition reaction curable silicone resins being preferred.
The curable silicone resin is preferably composed of a silicone resin constituting a main component and a silicone resin constituting a curing agent that cures the main component. In the case of the addition reaction curable silicone resin, the silicone resin used as the main component is preferably an organopolysiloxane having an alkenyl group. The organopolysiloxane having an alkenyl group more preferably has two or more alkenyl groups.
The alkenyl group is not particularly limited, but examples thereof include those having 2 to 8 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, and octenyl groups, with the vinyl group being preferred from the viewpoints of ease of synthesis, reactivity, etc. The alkenyl group is preferably an alkenyl group directly bonded to a silicon atom.
Specific examples of organopolysiloxanes having alkenyl groups include organopolysiloxanes having vinyl groups at both ends, such as polydimethylsiloxane having vinyl groups at both ends, polyphenylmethylsiloxane having vinyl groups at both ends, a copolymer of dimethylsiloxane having vinyl groups at both ends and diphenylsiloxane, a copolymer of dimethylsiloxane having vinyl groups at both ends and phenylmethylsiloxane, and a copolymer of dimethylsiloxane having vinyl groups at both ends and diethylsiloxane.

The silicone resin used as the curing agent for the addition reaction curing type silicone resin is not particularly limited as long as it can cure the silicone resin, which is the main component described above, but organohydrogenpolysiloxane, which is an organopolysiloxane having a hydrosilyl group (SiH), is preferred. The organohydrogenpolysiloxane preferably has two or more hydrosilyl groups.

Organohydrogenpolysiloxanes include methylhydrosiloxane-dimethylsiloxane copolymers, polymethylhydrosiloxanes, polyethylhydrosiloxanes, and methylhydrosiloxane-phenylmethylsiloxane copolymers. These may or may not contain hydrosilyl groups at the ends.

The silicone resin may be, for example, silicone oil, such as methylphenyl silicone oil, dimethyl silicone oil, modified silicone oil, etc.
Silicone oil is liquid at room temperature and normal pressure when mixed, and is liquid or gel-like when used. That is, silicone oil is not cured by a curing agent or the like, and is substantially non-curable, being liquid or gel-like even after curing. Therefore, when silicone oil is used alone as a resin component or at a relatively high mixing ratio, it can make the heat dissipation member formed from the resin composition into a paste-like state.

The silicone resin contained in the resin composition has a viscosity at 25° C. of preferably 5 mPa·s or more and 1000 mPa·s or less, more preferably 30 mPa·s or more and 700 mPa·s or less, and even more preferably 100 mPa·s or more and 600 mPa·s or less.
The viscosity of the silicone resin may be measured using a viscometer (BROOKFIELD rotational viscometer DV-E) with a rotor of spindle No. 14 at a rotation speed of 5 rpm and a measurement temperature of 25°C.
By setting the viscosity range of the silicone resin within the above range, the viscosity of the resin composition can be set within a predetermined range, improving the coatability of the resin composition while maintaining a constant shape after coating, making it possible to easily place the resin composition on electronic components, etc.

In addition, when the resin composition is a two-component curing type and is either one-component or two-component, it may contain either a silicone resin as a base resin or a silicone resin as a curing agent as described above. More specifically, the resin composition preferably contains either an organopolysiloxane or an organohydrogenpolysiloxane having an alkenyl group.
However, even when constituting either one liquid or two liquid of a two-component curing type, the silicone resin may contain an organohydrogenpolysiloxane or an organopolysiloxane having an alkenyl group, in addition to the organopolysiloxane or organohydrogenpolysiloxane having an alkenyl group, as long as curing does not proceed.

In addition, in the case of a one-component curing type resin composition, or in the case of a two-component curing type resin composition in which one and two components are mixed, the resin composition may contain both a silicone resin as a base resin and a silicone resin as a curing agent. In other words, in the case of a one-component curing type resin composition, or in the case of a two-component curing type resin composition in which one and two components are mixed, the resin composition preferably contains both an organopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane.

The curable resin composition may contain a non-curable organopolysiloxane as the silicone resin, and may contain, for example, silicone oil in addition to the organopolysiloxane having an alkenyl group or the organopolysiloxane having a hydrosilyl group described above. Of course, the resin composition may be a non-curable silicone resin composition, and in such a case, for example, silicone oil may be used alone as the silicone resin.

(Epoxy resin)
The epoxy resin used as the resin component is an epoxy compound having at least one epoxy group, preferably two or more epoxy groups. The epoxy compound is a curable resin, and is usually a thermosetting resin.
Examples of the epoxy compound include bisphenol type, novolak type, naphthalene type, triphenolalkane type, biphenyl type, cyclic aliphatic type, halides thereof, and hydrogenated products thereof.
In addition, the epoxy resin may be an epoxy compound alone, but the epoxy resin is a resin containing the epoxy compound as the main component and further containing a curing agent. The curing agent is a polyaddition type or a catalyst type. Examples of the polyaddition type curing agent include polyamine curing agents, acid anhydride curing agents, polyphenol curing agents, polymercaptan, and dicyandiamide. Examples of the catalyst type curing agent include tertiary amines, imidazoles, and Lewis acid complexes. These may be used alone or in combination of two or more types.
Furthermore, when an epoxy resin is used, the resin composition is preferably a two-component curing type, which is cured by mixing one component containing a base agent with a second component containing a curing agent.

When the resin composition is of a two-component curing type and is composed of either one component or two components, it may contain either an epoxy compound constituting the base or a curing agent.
However, even in the case of a two-component type, the epoxy resin may contain a curing agent or an epoxy compound in addition to the epoxy compound or curing agent, as long as the curing does not proceed.
In addition, when the resin composition is a one-component curing type, or when the resin composition is a two-component curing type in which the one component and the two components are mixed, it is preferable that the resin composition contains both an epoxy compound as a base and a curing agent.

(Acrylic resin)
The acrylic resin used as the resin component may be, for example, a photocurable resin. The acrylic resin may be any component that forms an acrylic polymer when cured, and may include, for example, various acrylic compounds such as (meth)acrylates such as alkyl (meth)acrylates and hydroxyalkyl (meth)acrylates, (meth)acrylic acid, (meth)acrylamides, and urethane (meth)acrylates. The acrylic resin may also contain a vinyl monomer that is copolymerizable with the acrylic compound.

The resin content in the resin composition is preferably 3% by volume or more and 20% by volume or less, more preferably 10% by volume or more and 20% by volume or less, based on the total volume of the resin composition. If the volume ratio of the resin is equal to or more than these lower limits, the inorganic filler dispersed in the resin can be properly dispersed and maintained in the resin. Furthermore, if the volume ratio is equal to or less than these upper limits, a certain amount or more of the inorganic filler can be blended into the resin composition.

<Dispersant>
The resin composition of the present invention contains a dispersant having a structure different from that of the resin. By containing the dispersant, the wettability of the inorganic filler is improved, and the inorganic filler can be easily dispersed in the resin. Therefore, the viscosity of the resin composition can be kept low, and the thermal conductivity can be improved.
The dispersant can be a silicone compound having a polar group at its end.Here, the polar group can be, for example, an alkoxy group, a hydroxyl group, etc., and is preferably an alkoxy group.The polar group is preferably bonded to a Si atom, and therefore, the polar group is preferably a hydrolyzable silyl group such as a silanol group or an alkoxysilyl group, and is more preferably an alkoxysilyl group.
A silicone compound having a polar group at its terminal is preferably used when the resin is a silicone resin.

The resin composition contains a silicone compound having a polar group at the end as a dispersant, and the polar group of the dispersant bonds or interacts with a functional group such as a hydroxy group or a carboxy group on the surface of the inorganic filler, making it easier to disperse the inorganic filler in the resin. In particular, the alkoxy group is easily hydrolyzed and reacts with a hydroxy group or the like, and is easy to improve the dispersibility of the inorganic filler.
In addition, by using a silicone compound as a dispersant, the inorganic filler becomes particularly compatible with the resin when a silicone resin is used as the resin, making it easier to increase the volume ratio of the inorganic filler in the resin composition.

The silicone compound having a polar group at the end is preferably an organopolysiloxane having a hydrolyzable silyl group at the molecular chain end (hereinafter also referred to as organopolysiloxane (X)). The organopolysiloxane (X) may be linear or branched, or may be a mixture of linear and branched, but is preferably linear. In addition, as the organopolysiloxane (X), an organopolysiloxane having at least one hydrolyzable silyl group at the molecular chain end is preferable, an organopolysiloxane having at least one hydrolyzable silyl group at only one end is more preferable, and an organopolysiloxane having three hydrolyzable silyl groups at one end is even more preferable. Here, the hydrolyzable silyl group is more preferably an alkoxysilyl group, and even more preferably a methoxysilyl group.
The organopolysiloxane (X) has a hydrolyzable silyl group at its terminal, which makes it easier to react or interact with the functional groups present on the surface of the inorganic filler. In addition, the polysiloxane structure also improves the dispersibility of the inorganic filler.

Specifically, the organopolysiloxane (X) is preferably a compound represented by the following formula (1).

In formula (1), R ¹ is independently any one of an alkyl group having 1 to 20 carbon atoms, a halogenated alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms, and a plurality of R ¹ may be the same or different. R ² is independently any one of an alkyl group having 1 to 4 carbon atoms, and when there are a plurality of R ² , the plurality of R ² may be the same or different. R ³ is independently any one of an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group having 2 to 4 carbon atoms, and an acyl group having 2 to 4 carbon atoms, and when there are a plurality of R ³ , the plurality of R ³ may be the same or different. R ⁴ is an alkyl group having 1 to 8 carbon atoms. R ⁶ is an oxygen atom or a divalent organic group having 1 to 40 carbon atoms. m is an integer of 3 to 315. In formula (1), a is an integer of 0 to 2.

In the above formula (1), the alkyl group in R ¹ may be linear or branched, or may have a cyclic structure. More specifically, examples of the alkyl group include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl groups, branched alkyl groups such as isopropyl, tertiary butyl, isobutyl, 2-methylundecyl, and 1-hexylheptyl groups, and cyclic alkyl groups such as cyclopentyl, cyclohexyl, and cyclododecyl groups.
Examples of halogenated alkyl groups include a chloromethyl group, a 3,3,3-trifluoropropyl group, a 3-chloropropyl group, etc. Examples of aryl groups include a phenyl group, a tolyl group, a xylyl group, etc. Examples of aralkyl groups include a benzyl group, a phenethyl group, a 2-(2,4,6-trimethylphenyl)propyl group, etc.
Among these, R ¹ is preferably an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and even more preferably a methyl group. In the compound of formula (1), it is preferable that 80% or more of R ¹ are methyl groups, more preferably 90% or more are methyl groups, and even more preferably all of R ¹ are methyl groups.

In the above formula (1), R ² is an alkyl group having 1 to 4 carbon atoms, and when there are multiple R ² (i.e., when a is 2), the multiple R ² may be the same or different. The alkyl group may be linear or branched. Among them, R ² is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably a methyl group. Furthermore, a is an integer of 0 to 2, and a is preferably 0 or 1, and more preferably 0.

In the above formula (1), R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group having 2 to 4 carbon atoms, or an acyl group having 2 to 4 carbon atoms. When there are multiple R ³ (i.e., when a is 0 or 1), the multiple R ³ may be the same or different. Furthermore, the alkyl group, alkoxyalkyl group, and acyl group in R ³ may be linear or branched. Among these, R ³ is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group.

In the above formula (1), R ⁴ is an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 2 to 6 carbon atoms, and more preferably a butyl group.
In the above formula (1), R ⁶ is preferably a group represented by the following formula (2), an oxygen atom, or a divalent hydrocarbon group having 1 to 20 carbon atoms, and more preferably a group represented by the following formula (2) or a divalent hydrocarbon group having 1 to 20 carbon atoms. Here, the divalent hydrocarbon group having 1 to 20 carbon atoms is preferably an alkylene group, and the alkylene group may be linear or branched. The divalent hydrocarbon group having 1 to 20 carbon atoms is preferably an alkylene group having 2 to 10 carbon atoms, more preferably an alkylene group having 2 to 8 carbon atoms, and even more preferably an alkylene group having 2 to 4 carbon atoms, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a methylethylene group, and among these, an ethylene group is preferable.

In formula (2), R ⁵ is a divalent hydrocarbon group having 1 to 20 carbon atoms, and multiple R ^5s may be the same or different. * represents the bonding position to the silicon atom in R ¹ -Si-R ¹ , and ** represents the bonding position to the silicon atom in SiR ² _a (OR ³ ) _3-a .
The divalent hydrocarbon group in ^R5 is preferably an alkylene group, which may be linear or branched. ^R5 is preferably an alkylene group having 2 to 10 carbon atoms, more preferably an alkylene group having 2 to 8 carbon atoms, even more preferably an alkylene group having 2 to 4 carbon atoms, and still more preferably an alkylene group represented by _-CH2 - _CH2 - _CH2- or -CH( _CH3 ) _-CH2- .

In formula (1), m represents the number of repetitions and is an integer from 3 to 315, preferably an integer from 4 to 280, more preferably an integer from 5 to 220, and even more preferably an integer from 5 to 100.

As the dispersant, other than silicone compounds can be used, and polymeric dispersants other than silicone compounds can be used. As the polymeric dispersant used, a polymeric compound having a functional group can be mentioned. As the polymeric compound, for example, acrylic, vinyl, polyester, polyurethane, polyether, epoxy, polystyrene, amino, etc. can be mentioned. In addition, as the functional group, a carboxyl group, a phosphoric acid group, a sulfonic acid group, a carboxylate group, a phosphoric acid ester group, a sulfonic acid ester group, a hydroxyl group, an amino group, a quaternary ammonium base, an amide group, etc. can be mentioned, and a phosphoric acid ester group is preferable.
A polymeric dispersant other than a silicone compound is preferably used when the resin contains a resin other than a silicone resin, such as an epoxy resin or an acrylic resin.

The functional groups of the polymer dispersants described above interact with the functional groups on the surface of the inorganic filler, making it easier to disperse the inorganic filler in the resin. In addition, by being a polymer compound other than a silicone compound, the inorganic filler becomes particularly compatible with the resin when a resin component other than a silicone resin (e.g., an epoxy resin or an acrylic resin) is used as the resin, making it easier to increase the volume ratio of the inorganic filler in the resin composition.

In addition, dispersants other than polymer dispersants can also be used, for example, alkoxysilane compounds can also be used. An alkoxysilane compound is a compound having a structure in which one to three of the four bonds that a silicon atom (Si) has are bonded to an alkoxy group, and the remaining bonds are bonded to an organic substituent. The alkoxy group of an alkoxysilane compound is a hydrolyzable group, and examples of such groups include a methoxy group, an ethoxy group, a protoxy group, a butoxy group, a pentoxy group, and a hexatoxy group. Among these, an alkoxysilane compound having a methoxy group or an ethoxy group is preferred.
From the viewpoint of increasing the affinity with the inorganic filler, the number of alkoxy groups in the alkoxysilane compound is preferably 3. Therefore, the alkoxysilane compound is more preferably at least one selected from a trimethoxysilane compound and a triethoxysilane compound.

Functional groups contained in the organic substituents of the alkoxysilane compound include, for example, acryloyl groups, alkyl groups, carboxyl groups, vinyl groups, methacryl groups, aromatic groups, amino groups, isocyanate groups, isocyanurate groups, epoxy groups, hydroxyl groups, and mercapto groups.

From the viewpoint of increasing compatibility with silicone resins and enhancing dispersibility of inorganic fillers, the alkoxysilane compound is preferably an alkylalkoxysilane compound having an alkyl group bonded to a silicon atom. The number of carbon atoms in the alkyl group bonded to the silicon atom is preferably 4 or more. In addition, from the viewpoint of keeping the viscosity of the resin composition low by having the alkoxysilane compound itself relatively low, the number of carbon atoms in the alkyl group bonded to the silicon atom is preferably 16 or less.

Preferred alkylalkoxysilane compounds include n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, and n-decyltrimethoxysilane.
Further, examples of alkoxysilane compounds other than alkylalkoxysilane compounds include 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and 3-phenylaminopropyltrimethoxysilane.
As the dispersant, the above-mentioned compounds may be used alone or in combination of two or more.

The content of the dispersant in the resin composition is preferably 5% by mass or more and 40% by mass or less, and more preferably 5% by mass or more and 20% by mass or less, based on the total amount of the resin composition excluding the inorganic filler. If the content is equal to or more than these lower limits, the inorganic filler can be properly dispersed in the resin composition, making it easier to compound. Also, if the content is equal to or less than the upper limit, dispersibility commensurate with the content can be imparted.

(Other additives)
When the resin composition is of a curing type, it may contain a curing catalyst as appropriate. For example, when an addition reaction curing type silicone resin is used, examples of the curing catalyst include platinum catalysts, palladium catalysts, and rhodium catalysts. These curing catalysts are catalysts for curing the silicone resin as the main agent and the silicone resin as the curing agent. The amount of the curing catalyst is usually 0.1 to 200 ppm, preferably 0.5 to 100 ppm, based on the mass of the silicone resin. When the resin composition is of a two-component curing type, the curing catalyst is preferably blended in the first component containing the main agent, but may be contained in the second component containing the curing agent.

The resin composition of the present invention may contain additives commonly used in heat dissipation materials, such as antioxidants, heat stabilizers, colorants, flame retardants, and antistatic agents, as necessary. In addition, when a curable resin such as a thermosetting resin is used, the resin composition may contain a reaction inhibitor. By containing a reaction inhibitor to suppress the catalytic activity of the curing catalyst, the shelf life and pot life of the resin composition can be extended. In addition, when a photocurable resin is used, the resin composition may contain a photopolymerization initiator.

(Thermal Conductivity of Resin Composition)
The thermal conductivity of the resin composition of the present invention is, for example, 6.0 W/(m·K) or more, preferably 9.0 W/(m·K) or more, more preferably 10 W/(m·K) or more, and even more preferably 11 W/(m·K) or more. The higher the thermal conductivity of the resin composition, the better the heat dissipation, but it is preferable that the thermal conductivity is, for example, 25 W/(m·K) or less.

(Viscosity of resin composition)
In addition, the resin composition of the present invention may have a viscosity at 25° C. of a certain value or less. By setting the viscosity at a certain value or less, it becomes easier to improve the coatability, moldability, etc. Specifically, the viscosity of the resin composition at 25° C. is preferably 400 mPa·s or less, more preferably 300 mPa·s or less, and even more preferably 200 mPa·s or less.
The viscosity of the resin composition at 25°C is not particularly limited, but in order to prevent dripping and the like, it is preferably 15 mPa·s or more, more preferably 50 mPa·s or more, and even more preferably 100 mPa·s or more.
The viscosity of the resin composition is a viscosity at 25° C., and can be measured by a Brookfield B type viscometer. As a measuring device, for example, “HB DVE” manufactured by Eiko Seiki Co., Ltd. can be used. The rotation speed is set to 10 rpm, and the value 3 minutes after the start of rotation is taken as the viscosity.
In addition, the viscosity of the resin composition refers to the viscosity of the resin composition before curing if the resin composition is curable. For example, if the resin composition is a two-component curing type and is a mixture of a first component and a second component, the viscosity refers to the viscosity immediately after mixing the first component and the second component.

[Heat dissipation material]
The heat dissipation member of the present invention is formed by the above-mentioned resin composition. For example, when the resin component contains a curable resin, the resin composition is formed into a predetermined shape, and then appropriately heated and cured to obtain a heat dissipation member molded into a predetermined shape. In addition, when a photocurable resin is used, the resin composition may be formed into a predetermined shape and then cured by irradiating it with light such as ultraviolet light. In addition, even when the resin component does not contain a curable resin, the resin composition may be formed into a predetermined shape or an indefinite shape to form a heat dissipation member. The method of forming the resin composition into a predetermined shape is not particularly limited, and the resin composition may be formed into a thin film, sheet, block, or indefinite shape by coating, casting, potting, extrusion molding, or the like. Coating may be performed using, for example, a dispenser.
In the case of a two-component curing type, the mixture obtained by mixing the first and second components is formed into a desired shape, and then cured to obtain a heat dissipation component molded into a desired shape.

The heat dissipation member of the present invention is used, for example, in electronic devices. That is, the present invention also provides an electronic device equipped with a heat dissipation member. The heat dissipation member of the present invention has high thermal conductivity, and therefore can ensure high heat dissipation when used inside an electronic device. More specifically, the heat dissipation member is placed on an electronic component and used to dissipate heat generated by the electronic component. It is also preferable that the heat dissipation member of the present invention is placed and used so as to fill the gap between two opposing members. The two opposing members may be, for example, one electronic component and the other a heat sink for dissipating heat from the electronic component, a housing for an electronic device, a substrate, or the like.

The present invention will be clarified below by showing specific examples and comparative examples of the present invention, but the present invention is not limited to the following examples.
The evaluation methods are as follows:

[Average particle size]
The average particle size of each inorganic filler was determined by measuring the 50% particle size (D50) in the cumulative particle size distribution on a volume basis, using the method described in the specification.

[Vickers hardness]
A pyramidal indenter made of a regular square pyramid diamond with an opposing angle of 136 degrees was pressed into the surface of the material, creating an indentation in the test surface. The Vickers hardness was calculated from the quotient obtained by dividing the load F (N) applied by the surface area calculated from the diagonal length d (mm) of the indentation.
Specifically, a Shimadzu Corporation "G32-FA" was used, and the average value of five measured values was calculated under conditions of a load of 10 N and an indenter driving time of 30 seconds.

[Chip damage evaluation]
1 g of the resin composition of each Example and Comparative Example was sandwiched between two silicon wafers of 200 μm thickness and 1 cm square to prepare a silicon wafer/resin composition/silicon wafer structure. The structure was crushed with a crushing load of 10 N and a compression speed of 0.5 mm/s until the thickness reached the size of the maximum particle filler contained in the resin composition, and then the silicon wafer was observed with an optical microscope to confirm the presence or absence of cracks. The same experiment was performed 200 times to confirm the frequency of cracks (breakage) of the silicon wafer.
⊚: No cracks occurred.
A: The crack occurred 1 or more times but less than 5 times.
x: Cracks occurred 5 or more times.

[Thermal conductivity evaluation]
The thermal conductivity was calculated from the thermal resistance of the resin composition of each of the Examples and Comparative Examples measured at room temperature (23° C.) using a “DynTIM” device manufactured by Mentor Graphics in accordance with ASTM D5470.
◎: 10 W/mK or more 〇: 6 W/mK or more but less than 10 W/mK ×: Less than 6 W/mK

The components used in each of the examples and comparative examples are as follows.
<Resin>
Silicone resin: Dimethylpolysiloxane, 110 mPa·S, specific gravity 0.97
Epoxy resin: ethylene glycol diglycidyl ether, epoxy equivalent 268 (g/eq.), 70 mPa·s, specific gravity 0.97
Acrylic resin: a mixture of acrylic resin (1) (product name "4-hydroxybutyl acrylate", manufactured by Osaka Organic Chemical Industry Co., Ltd.) and acrylic resin (2) (product name "CN9005", manufactured by ARKEMA Co., Ltd.) (mass ratio: acrylic resin (1):acrylic resin (2) = 20:1), specific gravity 0.97

When using the above epoxy resin, the following epoxy resin curing agents were used:
Epoxy resin hardener: modified aliphatic amine hardener, amine value 630 (KOHmg/g), 165mPa·s, specific gravity 0.97

<Dispersant>
Decyltrimethoxysilane ("KBM3103" manufactured by Shin-Etsu Chemical Co., Ltd.), specific gravity 0.97

<Diamond: Vickers hardness 70 GPa>
Diamond 1: average diameter 181 μm, truncated octahedron, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 2: average diameter 125 μm, truncated octahedron, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 3: average diameter 71 μm, truncated octahedron, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 4: average diameter 54 μm, truncated octahedron, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 5: average diameter 25 μm, truncated octahedron, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 6: average diameter 52 μm, regular octahedron Diamond 7: average particle size 4.8 μm, irregular, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 8: average particle size 9.64 μm, irregular, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 9: average particle size 25 μm, irregular, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 10: average particle size 55 μm, irregular, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Tomei Diamond Diamond 11: average particle size 0.1 μm, irregular, thermal conductivity 2000 W/mK, specific gravity 3.52, made by Daicel

<Cubic boron nitride: Vickers hardness 50 GPa>
Cubic boron nitride: average particle size 54 μm, truncated octahedron, thermal conductivity 600 W/mK, specific gravity 3.48, manufactured by Tomei Diamond

<Alumina: Vickers hardness 15.2 GPa>
Alumina 1: average particle size 3 μm, rounded, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by Sumitomo Chemical Alumina 2: average particle size 0.4 μm, rounded, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by Sumitomo Chemical Alumina 3: average particle size 9 μm, rounded, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by Showa Denko Alumina 4: average particle size 35 μm, tetradecahedral, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by DIC Alumina 5: average particle size 0.25 μm, spherical, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by Admatechs Alumina 6: average particle size 50 μm, spherical, thermal conductivity 36 W/mK, specific gravity 3.94, manufactured by DENKA

<Aluminum nitride: Vickers hardness 10.4 GPa>
Aluminum nitride 1: average particle size 1 μm, irregular, thermal conductivity 260 W/mK, specific gravity 3.26, manufactured by Tokuyama Aluminum nitride 2: average particle size 5 μm, irregular, thermal conductivity 260 W/mK, specific gravity 3.26, manufactured by Tokuyama Aluminum nitride 3: average particle size 5 μm, irregular, thermal conductivity 260 W/mK, specific gravity 3.26, manufactured by Toyo Aluminum Aluminum nitride 4: average particle size 50 μm, spherical, thermal conductivity 260 W/mK, specific gravity 3.26, manufactured by Showa Denko Aluminum nitride 5: average particle size 5 μm, spherical, thermal conductivity 260 W/mK, specific gravity 3.26, manufactured by Maruwa

<Magnesium oxide: Vickers hardness 6 GPa>
Magnesium oxide 1: average particle size 2.1 μm, cubic, thermal conductivity 40 W/mK, specific gravity 3.58, manufactured by JFE Magnesium oxide 2: average particle size 2 μm, irregular, thermal conductivity 40 W/mK, specific gravity 3.58, manufactured by Sakai Chemical Magnesium oxide 3: average particle size 0.5 μm, irregular, thermal conductivity 40 W/mK, specific gravity 3.58, manufactured by Sakai Chemical Magnesium oxide 4: average particle size 50 μm, irregular, thermal conductivity 40 W/mK, specific gravity 3.58, manufactured by Sakai Chemical

<Boron nitride: Vickers hardness 5 GPa>
Boron nitride 1: average particle size 13 μm, amorphous, thermal conductivity 60 W/mK, specific gravity 2.26, Momentive Boron nitride 2: average particle size 45 μm, amorphous, thermal conductivity 60 W/mK, specific gravity 2.26, Momentive Boron nitride 3: average particle size 12 μm, amorphous, thermal conductivity 60 W/mK, specific gravity 2.26, Momentive

<Zinc oxide: Vickers hardness 6 GPa>
・Zinc oxide 1: average particle size 4.2 μm, amorphous, thermal conductivity 40 W/mK, specific gravity 5.78, manufactured by Hakusui Tech ・Zinc oxide 2: average particle size 0.713 μm, amorphous, thermal conductivity 40 W/mK, specific gravity 5.78, manufactured by Hakusui Tech ・Zinc oxide 3: average particle size 0.516 μm, amorphous, thermal conductivity 40 W/mK, specific gravity 5.78, manufactured by Hakusui Tech ・Zinc oxide 4: average particle size 10 μm, amorphous, thermal conductivity 40 W/mK, specific gravity 5.78, manufactured by Sakai Chemical

[Examples 1 to 43, Comparative Examples 1 to 14]
Resin compositions were prepared by mixing the components according to the formulations shown in Tables 1, 3, 5, 7, and 9. The resin compositions were evaluated for chip breakage and thermal conductivity. The results are shown in Tables 2, 4, 6, 8, and 10.

*Comparative Examples 1 to 5 do not contain inorganic fillers with a Vickers hardness difference of 20 GPa or more, and therefore there are no inorganic fillers that correspond to the first inorganic filler and the second inorganic filler. However, for the sake of convenience in comparison with other examples, the inorganic filler with a higher Vickers hardness is listed in the column for the first inorganic filler, and the inorganic filler with a lower Vickers hardness is listed in the column for the second inorganic filler.

The resin compositions of Examples 1 to 43, which satisfy the requirements of the present invention, had high thermal conductivity and low chip breakage frequency. This shows that the resin compositions of the present invention have excellent heat dissipation properties, low stress during compression, and can suppress breakage of components.
In contrast, the resin compositions of the comparative examples which do not satisfy the requirements of the present invention had low thermal conductivity or high frequency of chip breakage, resulting in results inferior to those of the examples.

Claims (8)

A resin composition containing a resin and an inorganic filler,
The inorganic filler includes a first inorganic filler and a second inorganic filler having a Vickers hardness difference of 20 GPa or more, the Vickers hardness of the first inorganic filler being greater than the Vickers hardness of the second inorganic filler,
The average particle size (α) of the first inorganic filler is larger than the average particle size (β) of the second inorganic filler,
a ratio [(B)/(A)] of the volume filling rate (B) of the second inorganic filler to the volume filling rate (A) of the first inorganic filler is 0.08 or more and 0.42 or less;
A resin composition having a total inorganic filler content of 80 volume % or more. The resin composition according to claim 1, wherein the thermal conductivity of the first inorganic filler is higher than the thermal conductivity of the second inorganic filler. The resin composition according to claim 1 or 2, wherein the first inorganic filler is diamond or cubic boron nitride. The resin composition according to claim 1 or 2, wherein the content of the first inorganic filler is 20% by volume or more and 80% by volume or less based on the total amount of the resin composition. The resin composition according to claim 1 or 2, further comprising a dispersant, the content of the dispersant being 5 to 40 mass% based on the total amount of the resin composition excluding the inorganic filler. The resin composition according to claim 1 or 2, having a viscosity of 400 mPa·s or less at 25°C. A heat dissipation member formed from the resin composition according to claim 1 or 2. An electronic device comprising an electronic component and the heat dissipation member according to claim 7 arranged on the electronic component.