JP2018188628A - Thermosetting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting material that has improved thermal conductivity although it is made using agglomerate of boron nitride particles, and can prevent the occurrence of voids.SOLUTION: A thermosetting material contains a thermosetting compound, a thermosetting agent, and a plurality of boron nitride particles. The boron nitride particles include agglomerate obtained by aggregation of boron nitride particles. The minimum melt viscosity of the thermosetting material when heating it from 25°C to curing at a temperature rise rate of 5°C/min is 1×10Pa s or more and 1×10Pa s or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermosetting material including an aggregate of boron nitride particles in which a plurality of boron nitride particles are aggregated.

  In recent years, miniaturization and high performance of electronic or electric devices have been advanced. Along with this, the mounting density of electronic components is increasing, and the need to dissipate heat generated from electronic components is increasing. Heat generation is a problem directly related to the reliability of devices and equipment, and how to dissipate heat quickly is an urgent issue.

  As one method for solving the above problems, a ceramic substrate having high thermal conductivity such as an alumina substrate or an aluminum nitride substrate is used as a heat dissipation substrate for mounting a power semiconductor device. However, these substrates have a problem that it is difficult to make a multi-layer, the workability is poor, and the cost is very high.

  On the other hand, in order to dissipate heat, a thermally conductive composition containing a thermally conductive filler is used. The following Patent Documents 1 to 3 disclose fillers that can be used as heat conductive fillers.

  In the following Patent Document 1, 100 parts by weight of spherical heat conductive particles (A) having an average primary particle size of 0.1 to 10 μm, and 0.1 to 0.1 organic binder (B) having a reactive functional group. An easily deformable aggregate (D) containing 30 parts by weight is disclosed. The average particle diameter of the easily deformable aggregate (D) is 2 to 100 μm. The average compressive force required for compressive deformation at a compressive deformation rate of 10% of the easily deformable aggregate (D) is 5 mN or less.

Patent Document 2 below discloses boron nitride aggregated particles. The boron nitride aggregated particles have a specific surface area of 10 m ² / g or more and a total pore volume of 2.15 cm ³ / g or less. The surface of the boron nitride aggregated particles is composed of primary boron nitride particles having an average particle size of 0.05 μm or more and 1 μm or less. The maximum particle diameter of the boron nitride aggregated particles on the volume basis is larger than 25 μm and not larger than 200 μm.

  Patent Document 3 below discloses a heat conductive sheet in which boron nitride powder is dispersed as a heat conductive filler in an organic matrix material. The boron nitride powder contains secondary aggregate particles having a particle size of 50 μm or more at 1 to 20% by weight.

Japanese Patent Laid-Open No. 2015-10200 Japanese Patent Laid-Open No. 2015-6980 JP 2003-60134 A

  In the composition containing conventional boron nitride particles as described in Patent Documents 1 to 3, the thermal conductivity can be increased to some extent.

  However, in the composition containing conventional boron nitride particles as described in Patent Documents 1 to 3, even if the thermal conductivity can be increased to some extent, voids may occur when the composition is cured. . When voids are generated in the cured product, the adhesiveness and insulating properties are reduced.

  An object of the present invention is to provide a thermosetting material that can increase the thermal conductivity and suppress the generation of voids even though an aggregate of boron nitride particles is used. .

According to a wide aspect of the present invention, the thermosetting compound includes a thermosetting compound, a thermosetting agent, and a plurality of boron nitride particles, and the boron nitride particles include an aggregate in which the boron nitride particles are aggregated. A thermosetting material having a minimum melt viscosity of 1 × 10 ³ Pa · s or more and 1 × 10 ⁴ Pa · s or less when heated at a heating rate of 5 ° C./min from 25 ° C. to curing is provided. Is done.

  On the specific situation with the thermosetting material which concerns on this invention, the average aspect-ratio of the said aggregate is 1-5.

  On the specific situation with the thermosetting material which concerns on this invention, the said thermosetting compound contains an epoxy compound.

  On the specific situation with the thermosetting material which concerns on this invention, the said aggregate is the surface treatment thing by a surface treating agent.

  On the specific situation with the thermosetting material which concerns on this invention, content of the said boron nitride particle is 10 volume% or more and 80 volume% or less in 100 volume% of components except a solvent.

  On the specific situation with the thermosetting material which concerns on this invention, the said thermosetting material is a thermosetting sheet.

The thermosetting material according to the present invention includes a thermosetting compound, a thermosetting agent, and a plurality of boron nitride particles. In the thermosetting material according to the present invention, the boron nitride particles include an aggregate in which the boron nitride particles are aggregated. In the thermosetting material according to the present invention, the minimum melt viscosity when heated at a rate of temperature increase of 5 ° C./min until the thermosetting material is cured from 25 ° C. is 1 × 10 ³ Pa · s or more, 1 × 10 ⁴ Pa · s or less. Since the thermosetting material according to the present invention has the above-described configuration, the thermal conductivity is increased and the generation of voids is suppressed even though the aggregate of boron nitride particles is used. can do.

FIG. 1 is a cross-sectional view schematically showing a cured product of a thermosetting material according to an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail.

  The thermosetting material according to the present invention includes (A) a thermosetting compound, (B) a thermosetting agent, and a plurality of (C) boron nitride particles. (C) The boron nitride particles include an aggregate in which the boron nitride particles are aggregated (also referred to as an aggregate of (C1) boron nitride particles or (C1) an aggregate).

In the thermosetting material according to the present invention, the minimum melt viscosity when heated at a rate of temperature increase of 5 ° C./min until the thermosetting material is cured from 25 ° C. is 1 × 10 ³ Pa · s or more, 1 × 10 ⁴ Pa · s or less.

  In the present invention, since the above-described configuration is provided, (C1) it is possible to increase the thermal conductivity and suppress the generation of voids even though the aggregate of boron nitride particles is used. it can. In this invention, since the said minimum melt viscosity is more than the said minimum, thermal conductivity becomes high. In the present invention, since the minimum melt viscosity is not more than the above upper limit, generation of voids can be suppressed.

  Further, (C) boron nitride particles and (C1) aggregates contribute to the improvement of thermal conductivity. In the (C1) aggregate, voids exist between (C) boron nitride particles constituting the (C1) aggregate. If gas or the like remains in the voids at the curing stage, it causes voids in the cured product. By controlling the minimum melt viscosity of the thermosetting material to the upper limit or less, the thermosetting component can be satisfactorily entered into the voids at the curing stage. As a result, generation of voids in the cured product can be suppressed. Moreover, when a void generate | occur | produces in hardened | cured material, adhesiveness and insulation will fall. In the present invention, since the generation of voids can be suppressed, the adhesiveness and the insulating properties can be kept high. By controlling the minimum melt viscosity of the thermosetting material to be equal to or higher than the lower limit, the fluidity of the thermosetting material can be appropriately suppressed. Furthermore, handling property can be improved when the thermosetting material is a thermosetting sheet.

From the viewpoint of effectively increasing the thermal conductivity and effectively suppressing the generation of voids, the minimum melt viscosity when the thermosetting material is heated at a heating rate of 5 ° C./min until it is cured from 25 ° C. is , Preferably 1 × 10 ³ Pa · s or more, and preferably 1 × 10 ⁴ Pa · s or less. When the minimum melt viscosity is less than the lower limit, it is difficult to moderately suppress the flow of the thermosetting material during thermosetting, the shape of the thermosetting material cannot be maintained, and a resin flow occurs. On the other hand, if the minimum melt viscosity exceeds the above upper limit, it becomes difficult to effectively suppress the generation of voids, and the thermal conductivity and the insulation are reduced.

  As a method of adjusting the minimum melt viscosity to the above range, a method using a thermosetting compound having a low melt viscosity, a method of surface-treating boron nitride particles, a method of controlling the particle size distribution of boron nitride particles, a spherical shape The method of adding a submicron filler, the method of combining these methods, etc. are mentioned.

  The minimum melt viscosity is a value at which the viscosity becomes the lowest in the above viscosity measurement. The minimum melt viscosity is measured as follows.

  Using a rheometer (“DynAlyser” manufactured by Rheologica), the thermosetting material is sandwiched between a glass plate and a parallel plate (diameter 20 mm), and the temperature is increased from 25 ° C. until curing at a frequency of 1 Hz and a strain of 1%. Changes in melt viscosity are measured by heating at 5 ° C./min. From the obtained results, the minimum melt viscosity is defined as the minimum melt viscosity. For example, when the curing is completed by 200 ° C., the viscosity increases when cured, so that the temperature may be heated from 20 ° C. to 200 ° C. when the minimum melt viscosity is measured.

  Moreover, when measuring the said minimum melt viscosity, it heats at a temperature increase rate of 5 degree-C / min until it hardens | cures from 25 degreeC. This heating condition is a heating condition for measuring the minimum melt viscosity in the present invention. When using the thermosetting material in this invention, it is not necessary to heat at a temperature increase rate of 5 degree-C / min until it hardens | cures from 25 degreeC.

  From the viewpoint of effectively increasing both thermal conductivity and voltage resistance, it is preferable that the boron nitride constituting (C) boron nitride particles is hexagonal boron nitride.

  Since it is more excellent due to the effect of the present invention, it is preferable that each of (C) boron nitride particles that are not aggregated and (C) boron nitride particles that constitute the aggregates have a scaly shape. In each of the non-aggregated (C) boron nitride particles and (C1) boron nitride particles constituting the aggregate, the ratio of the average major axis to the average thickness is preferably 2 or more, more preferably 3 or more. Yes, preferably 200 or less, more preferably 100 or less.

  From the viewpoint of effectively increasing thermal conductivity and controlling the compressive strength within an appropriate range, a plurality of (C) boron nitride particles (non-aggregated (C) boron nitride particles and (C1) aggregates are formed. The average primary particle size of (C) boron nitride particles) is preferably 0.1 μm or more, more preferably 0.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less.

  (C) The average primary particle diameter of the boron nitride particles means the average particle diameter on the volume basis of the primary particles. (C) The average primary particle diameter of boron nitride particles can be measured using a “dry laser diffraction particle size distribution measuring device (model number: MASTERSIZER 3000)” manufactured by Malvern.

  (C1) The average aspect ratio of the aggregate of boron nitride particles is preferably 1 or more, preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, still more preferably 1.8 or less, particularly preferably. 1.6 or less, most preferably 1.5 or less. When the average aspect ratio of the aggregate of (C1) boron nitride particles is not less than the above lower limit and not more than the above upper limit, (C) the boron nitride particles can be filled with high density, and the thermal conductivity can be effectively increased. And generation | occurrence | production of a void can be suppressed effectively.

  The aspect ratio is major axis / minor axis. The average aspect ratio is obtained by averaging the aspect ratios of a plurality of (C1) aggregates. It is preferable to average the aspect ratio of 50 (C1) aggregates arbitrarily selected.

  From the viewpoint of further enhancing dispersibility in the resin, stability over time, and thermal conductivity, the average particle size of the aggregate of (C1) boron nitride particles is preferably 1 μm or more, more preferably 5 μm or more, preferably It is 100 μm or less, more preferably 80 μm or less.

  (C1) The average particle diameter of the aggregate of boron nitride particles is determined by measuring the particle diameter on a volume basis by particle size distribution measurement. (C1) The average particle diameter of the aggregate of boron nitride particles can be measured using a “dry laser diffraction particle size distribution measuring device (model number: MASTERSIZER 3000)” manufactured by Malvern.

  From the viewpoint of effectively increasing the thermal conductivity, the average sphericity of the aggregate of (C1) boron nitride particles is preferably 0.7 or more, more preferably 0.75 or more, and further preferably 0.8 or more. is there.

  The average sphericity is obtained by averaging the sphericity of a plurality of (C1) aggregates. (C1) The average sphericity of the aggregate is determined by a method of measuring the sphericity from an arbitrary number of particle images obtained by microscopic observation. (C1) The average sphericity of the aggregate can be measured using “Particle Image Analyzer (model number: Morphologi G3)” manufactured by Malvern. Measurement conditions are set to a lens magnification of 10 times and a particle count of 5000.

  From the viewpoint of effectively increasing the thermal conductivity and effectively suppressing the generation of voids, it is preferable that the aggregate (C1) is a surface-treated product with a surface treatment agent.

  Preferable examples of the surface treatment agent include silane coupling agents and surfactants.

  (C1) Examples of the method for producing an aggregate of boron nitride particles include a spray drying method and a fluidized bed granulation method. A spray drying method (also called spray drying) is preferred. The spray drying method can be classified into a two-fluid nozzle method, a disk method (also called a rotary method), an ultrasonic nozzle method, and the like depending on the spray method, and any of these methods can be applied.

  From the viewpoint of effectively increasing the compressive strength and voltage resistance, the thermosetting material according to the present invention includes (A) a thermosetting compound, (B) a thermosetting agent, and (C) boron nitride particles (( C1) including aggregates) and (D) insulating fillers that are not boron nitride particles (simply described as (D) insulating fillers) are preferable.

  By adopting the composition containing the components (A) to (D), the heat dissipation of the cured product can be considerably enhanced. For example, (A) a thermosetting compound, (B) a thermosetting agent, (C) boron nitride particles (including (C1) aggregates), and (D) an insulating filler are used in combination. Compared with the case where no is used in combination, the heat dissipation, compression strength and voltage resistance are effectively increased. In the present invention, it is possible to achieve a high level of effects of high heat dissipation and high voltage resistance, which have been difficult to satisfy in the past.

  Hereinafter, other details of the present invention will be described.

((A) thermosetting compound)
(A) As thermosetting compounds, styrene compounds, phenoxy compounds, oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds Etc. (A) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of effectively increasing the thermal conductivity and effectively suppressing the generation of voids, the (A) thermosetting compound preferably contains an epoxy compound.

  (A) As the thermosetting compound, (A1) a thermosetting compound having a molecular weight of less than 10,000 (may be simply referred to as (A1) thermosetting compound) may be used. As the (A) thermosetting compound, (A2) a thermosetting compound having a molecular weight of 10,000 or more (simply described as (A2) thermosetting compound may be used) may be used. (A) As the thermosetting compound, both (A1) thermosetting compound and (A2) thermosetting compound may be used.

  Of the components contained in the thermosetting material, the content of the (A) thermosetting compound is preferably 10% by weight in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. As mentioned above, More preferably, it is 20 weight% or more. Among the components contained in the thermosetting material, the content of the (A) thermosetting compound is preferably 90% by weight in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. Below, more preferably 80% by weight or less, still more preferably 70% by weight or less, particularly preferably 60% by weight or less, and most preferably 50% by weight or less. (A) The adhesiveness and heat resistance of hardened | cured material become still higher that content of a thermosetting compound is more than the said minimum. (A) The coating property at the time of preparation of a thermosetting material becomes it high that content of a thermosetting compound is below the said upper limit.

  Among the components contained in the thermosetting material, the components other than the solvent, (C) boron nitride particles and (D) insulating filler are (C) boron nitride particles when the thermosetting material does not contain a solvent. And (D) a component excluding the insulating filler, and when the thermosetting material contains a solvent, it is a component excluding the solvent, (C) boron nitride particles and (D) the insulating filler. Among the components contained in the thermosetting material, components other than the solvent, (C) boron nitride particles, and (D) insulating filler are solvents when the thermosetting material does not contain (D) insulating filler. And (C) a component excluding boron nitride particles, and when the thermosetting material contains (D) insulating filler, it is a component excluding solvent, (C) boron nitride particles and (D) insulating filler. . The solvent is removed by volatilization when the thermosetting material is cured.

(A1) Thermosetting compound having a molecular weight of less than 10,000:
(A1) As a thermosetting compound, the thermosetting compound which has a cyclic ether group is mentioned. Examples of the cyclic ether group include an epoxy group and an oxetanyl group. The thermosetting compound having a cyclic ether group is preferably a thermosetting compound having an epoxy group or an oxetanyl group. (A1) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  The (A1) thermosetting compound may contain (A1a) a thermosetting compound having an epoxy group (sometimes simply referred to as (A1a) a thermosetting compound), and (A1b) an oxetanyl group. A thermosetting compound (which may be simply referred to as (A1b) thermosetting compound).

  From the viewpoint of further increasing the heat resistance and moisture resistance of the cured product, the (A1) thermosetting compound preferably has an aromatic skeleton.

  The aromatic skeleton is not particularly limited, and examples thereof include naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and bisphenol A skeleton. From the viewpoint of further improving the cold-heat cycle characteristics and heat resistance of the cured product, a biphenyl skeleton or a fluorene skeleton is preferable.

  (A1a) The thermosetting compound includes an epoxy monomer having a bisphenol skeleton, an epoxy monomer having a dicyclopentadiene skeleton, an epoxy monomer having a naphthalene skeleton, an epoxy monomer having an adamantane skeleton, an epoxy monomer having a fluorene skeleton, and a biphenyl skeleton. Epoxy monomers having a bi (glycidyloxyphenyl) methane skeleton, epoxy monomers having a xanthene skeleton, epoxy monomers having an anthracene skeleton, and epoxy monomers having a pyrene skeleton. These hydrogenated products or modified products may be used. (A1a) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  Examples of the epoxy monomer having a bisphenol skeleton include an epoxy monomer having a bisphenol A type, a bisphenol F type, and a bisphenol S type bisphenol skeleton.

  Examples of the epoxy monomer having a dicyclopentadiene skeleton include dicyclopentadiene dioxide and a phenol novolac epoxy monomer having a dicyclopentadiene skeleton.

  Examples of the epoxy monomer having a naphthalene skeleton include 1-glycidylnaphthalene, 2-glycidylnaphthalene, 1,2-diglycidylnaphthalene, 1,5-diglycidylnaphthalene, 1,6-diglycidylnaphthalene, 1,7-diglycidyl. Naphthalene, 2,7-diglycidylnaphthalene, triglycidylnaphthalene, 1,2,5,6-tetraglycidylnaphthalene and the like can be mentioned.

  Examples of the epoxy monomer having an adamantane skeleton include 1,3-bis (4-glycidyloxyphenyl) adamantane and 2,2-bis (4-glycidyloxyphenyl) adamantane.

  Examples of the epoxy monomer having a fluorene skeleton include 9,9-bis (4-glycidyloxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3-methylphenyl) fluorene, and 9,9-bis (4- Glycidyloxy-3-chlorophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-bromophenyl) fluorene, 9,9-bis (4-glycidyloxy-3-fluorophenyl) fluorene, 9,9-bis (4-Glycidyloxy-3-methoxyphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dimethylphenyl) fluorene, 9,9-bis (4-glycidyloxy-3,5-dichlorophenyl) Fluorene and 9,9-bis (4-glycidyloxy-3,5-dibromophenyl) Fluorene, and the like.

  Examples of the epoxy monomer having a biphenyl skeleton include 4,4'-diglycidylbiphenyl and 4,4'-diglycidyl-3,3 ', 5,5'-tetramethylbiphenyl.

  Examples of the epoxy monomer having a bi (glycidyloxyphenyl) methane skeleton include 1,1′-bi (2,7-glycidyloxynaphthyl) methane, 1,8′-bi (2,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,7-glycidyloxynaphthyl) methane, 1,8′-bi (3,7-glycidyloxynaphthyl) methane, 1,1′-bi (3,5-glycidyloxynaphthyl) methane 1,8'-bi (3,5-glycidyloxynaphthyl) methane, 1,2'-bi (2,7-glycidyloxynaphthyl) methane, 1,2'-bi (3,7-glycidyloxynaphthyl) Examples include methane and 1,2′-bi (3,5-glycidyloxynaphthyl) methane.

  Examples of the epoxy monomer having a xanthene skeleton include 1,3,4,5,6,8-hexamethyl-2,7-bis-oxiranylmethoxy-9-phenyl-9H-xanthene.

  Specific examples of the (A1b) thermosetting compound include, for example, 4,4′-bis [(3-ethyl-3-oxetanyl) methoxymethyl] biphenyl, 1,4-benzenedicarboxylic acid bis [(3-ethyl- 3-oxetanyl) methyl] ester, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, oxetane-modified phenol novolak, and the like. (A1b) Only 1 type may be used for a thermosetting compound and 2 or more types may be used together.

  From the viewpoint of further improving the heat resistance of the cured product, the (A1) thermosetting compound preferably includes a thermosetting compound having two or more cyclic ether groups.

  From the viewpoint of further improving the heat resistance of the cured product, the content of the thermosetting compound having two or more cyclic ether groups is preferably 70% by weight or more in 100% by weight of the (A1) thermosetting compound. More preferably, it is 80% by weight or more and 100% by weight or less. (A1) In 100% by weight of the thermosetting compound, the content of the thermosetting compound having two or more cyclic ether groups may be 10% by weight or more and 100% by weight or less. Further, the whole (A1) thermosetting compound may be a thermosetting compound having two or more cyclic ether groups.

  (A1) The molecular weight of the thermosetting compound is less than 10,000. (A1) The molecular weight of the thermosetting compound is preferably 200 or more, preferably 1200 or less, more preferably 600 or less, and still more preferably 550 or less. (A1) When the molecular weight of the thermosetting compound is equal to or more than the above lower limit, the adhesiveness of the surface of the cured product is lowered, and the handleability of the curable composition is further enhanced. (A1) When the molecular weight of the thermosetting compound is not more than the above upper limit, the adhesiveness of the cured product is further enhanced. Furthermore, the cured product is hard and hard to be brittle, and the adhesiveness of the cured product is further enhanced.

  In this specification, (A1) the molecular weight of the thermosetting compound is (A1) when the thermosetting compound is not a polymer, and (A1) when the structural formula of the thermosetting compound can be specified. It means the molecular weight that can be calculated from the structural formula. When the thermosetting compound (A1) is a polymer, it means the weight average molecular weight.

  Of the components contained in the thermosetting material, the content of (A1) thermosetting compound is preferably 10% by weight in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. As mentioned above, More preferably, it is 20 weight% or more. Of the components contained in the thermosetting material, the content of the (A1) thermosetting compound is preferably 90% by weight in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. Below, more preferably 80% by weight or less, still more preferably 70% by weight or less, particularly preferably 60% by weight or less, and most preferably 50% by weight or less. (A1) When the content of the thermosetting compound is not less than the above lower limit, the adhesiveness and heat resistance of the cured product are further enhanced. (A1) The coating property at the time of preparation of a thermosetting material becomes it high that content of a thermosetting compound is below the said upper limit.

(A2) Thermosetting compound having a molecular weight of 10,000 or more:
(A2) The thermosetting compound is a thermosetting compound having a molecular weight of 10,000 or more. Since the molecular weight of the (A2) thermosetting compound is 10,000 or more, the (A2) thermosetting compound is generally a polymer, and the above molecular weight generally means a weight average molecular weight.

  From the viewpoint of further improving the heat resistance and moisture resistance of the cured product, the (A2) thermosetting compound preferably has an aromatic skeleton. (A2) When the thermosetting compound is a polymer and (A2) the thermosetting compound has an aromatic skeleton, (A2) the thermosetting compound has an aromatic skeleton in any part of the whole polymer. What is necessary is just to have, it may have in the main chain frame | skeleton, and you may have in a side chain. From the viewpoint of further increasing the heat resistance of the cured product and further increasing the moisture resistance of the cured product, the (A2) thermosetting compound preferably has an aromatic skeleton in the main chain skeleton. (A2) As for a thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  The aromatic skeleton is not particularly limited, and examples thereof include naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton, and bisphenol A skeleton. A biphenyl skeleton or a fluorene skeleton is preferred. In this case, the thermal cycle resistance and heat resistance of the cured product are further enhanced.

  (A2) The thermosetting compound is not particularly limited. Styrene resin, phenoxy resin, oxetane resin, epoxy resin, episulfide compound, (meth) acrylic resin, phenol resin, amino resin, unsaturated polyester resin, polyurethane resin, silicone Examples thereof include resins and polyimide resins.

  From the viewpoint of suppressing the oxidative degradation of the cured product, further improving the heat cycle resistance and heat resistance of the cured product, and further reducing the water absorption of the cured product, (A2) the thermosetting compound is a styrene resin, It is preferably a phenoxy resin or an epoxy resin, more preferably a phenoxy resin or an epoxy resin, and further preferably a phenoxy resin. In particular, use of a phenoxy resin or an epoxy resin further increases the heat resistance of the cured product. Moreover, use of a phenoxy resin further lowers the elastic modulus of the cured product and further improves the cold-heat cycle characteristics of the cured product. In addition, the (A2) thermosetting compound does not need to have cyclic ether groups, such as an epoxy group.

  As the styrene resin, specifically, a homopolymer of a styrene monomer, a copolymer of a styrene monomer and an acrylic monomer, or the like can be used. Styrene polymers having a styrene-glycidyl methacrylate structure are preferred.

  Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, and pn-. Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl Examples include styrene and 3,4-dichlorostyrene.

  Specifically, the phenoxy resin is, for example, a resin obtained by reacting an epihalohydrin with a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with a divalent phenol compound.

  The phenoxy resin has a bisphenol A skeleton, bisphenol F skeleton, bisphenol A / F mixed skeleton, naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton or dicyclopentadiene skeleton. It is preferable. More preferably, the phenoxy resin has a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol A / F mixed skeleton, a naphthalene skeleton, a fluorene skeleton, or a biphenyl skeleton, and at least one of the fluorene skeleton and the biphenyl skeleton. More preferably, it has a skeleton. Use of the phenoxy resin having these preferable skeletons further increases the heat resistance of the cured product.

  The epoxy resin is an epoxy resin other than the phenoxy resin. Examples of the epoxy resins include styrene skeleton-containing epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, phenol novolac type epoxy resins, biphenol type epoxy resins, naphthalene type epoxy resins, and fluorene type epoxy resins. , Phenol aralkyl type epoxy resin, naphthol aralkyl type epoxy resin, dicyclopentadiene type epoxy resin, anthracene type epoxy resin, epoxy resin having adamantane skeleton, epoxy resin having tricyclodecane skeleton, and epoxy resin having triazine nucleus in skeleton Etc.

  (A2) The molecular weight of the thermosetting compound is 10,000 or more. (A2) The molecular weight of the thermosetting compound is preferably 30000 or more, more preferably 40000 or more, preferably 1000000 or less, more preferably 250,000 or less. (A2) When the molecular weight of the thermosetting compound is not less than the above lower limit, the cured product is hardly thermally deteriorated. (A2) When the molecular weight of the thermosetting compound is less than the above lower limit, it tends to be thermally deteriorated, the melt viscosity is lowered, and a resin flow is generated during thermosetting. When the molecular weight of the (A2) thermosetting compound is not more than the above upper limit, the compatibility between the (A2) thermosetting compound and other components is increased. As a result, the heat resistance of the cured product is further increased.

  Of the components contained in the thermosetting material, the content of (A2) thermosetting compound is preferably 20% by weight in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. Above, more preferably 30% by weight or more, preferably 60% by weight or less, more preferably 50% by weight or less. (A2) When the content of the thermosetting compound is not less than the above lower limit, the handleability of the thermosetting material is improved. (A2) When content of a thermosetting compound is below the said upper limit, dispersion | distribution of (C) boron nitride particle and (D) insulating filler will become easy.

((B) thermosetting agent)
(B) The thermosetting agent is not particularly limited. As the (B) thermosetting agent, an appropriate thermosetting agent capable of curing the (A) thermosetting compound can be used. In the present specification, the thermosetting agent (B) includes a curing catalyst. (B) As for a thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further increasing the heat resistance of the cured product, the (B) thermosetting agent preferably has an aromatic skeleton or an alicyclic skeleton. (B) The thermosetting agent preferably includes an amine curing agent (amine compound), an imidazole curing agent, a phenol curing agent (phenol compound) or an acid anhydride curing agent (acid anhydride), and includes an amine curing agent. Is more preferable. The acid anhydride curing agent includes an acid anhydride having an aromatic skeleton, a water additive of the acid anhydride or a modified product of the acid anhydride, or an acid anhydride having an alicyclic skeleton, It is preferable to include a water additive of an acid anhydride or a modified product of the acid anhydride.

  Examples of the amine curing agent include dicyandiamide, imidazole compounds, diaminodiphenylmethane, and diaminodiphenylsulfone. From the viewpoint of further improving the adhesion between the cured product, the heat conductor and the conductive layer, the amine curing agent is more preferably a dicyandiamide or an imidazole compound. From the viewpoint of further improving the storage stability of the curable composition, the (B) thermosetting agent preferably contains a curing agent having a melting point of 180 ° C. or higher, and an amine curing agent having a melting point of 180 ° C. or higher. More preferably.

  Examples of the imidazole curing agent include 2-undecylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 1-benzyl. 2-methylimidazole, 1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2- Undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2 '-Methyl Midazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6 [2′-Ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine Isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-dihydroxymethylimidazole Can be mentioned.

  Examples of the phenol curing agent include phenol novolak, o-cresol novolak, p-cresol novolak, t-butylphenol novolak, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolak, xylylene modified novolak, decalin modified novolak, poly ( And di-o-hydroxyphenyl) methane, poly (di-m-hydroxyphenyl) methane, and poly (di-p-hydroxyphenyl) methane. From the viewpoint of further enhancing the flexibility of the cured product and the flame retardancy of the cured product, a phenol resin having a melamine skeleton, a phenol resin having a triazine skeleton, or a phenol resin having an allyl group is preferable.

  Commercially available products of the phenol curing agent include MEH-8005, MEH-8010, MEH-8015, and MEH-8000H (all of which are manufactured by Meiwa Kasei Co., Ltd.), YLH903 (manufactured by Mitsubishi Chemical Corporation), LA-7052, and LA-7054. , LA-7751, LA-1356 and LA-3018-50P (all of which are manufactured by DIC Corporation), PS6313 and PS6492 (all of which are manufactured by Gunei Chemical Co., Ltd.), and the like.

  Examples of the acid anhydride having an aromatic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride include, for example, a styrene / maleic anhydride copolymer, a benzophenone tetracarboxylic acid anhydride, and a pyromellitic acid anhydride. , Trimellitic anhydride, 4,4'-oxydiphthalic anhydride, phenylethynyl phthalic anhydride, glycerol bis (anhydrotrimellitate) monoacetate, ethylene glycol bis (anhydrotrimellitate), methyltetrahydroanhydride Examples include phthalic acid, methylhexahydrophthalic anhydride, and trialkyltetrahydrophthalic anhydride.

  Examples of commercially available acid anhydrides having an aromatic skeleton, water additives of the acid anhydrides, or modified products of the acid anhydrides include SMA Resin EF30, SMA Resin EF40, SMA Resin EF60, and SMA Resin EF80 (any of the above Also manufactured by Sartomer Japan), ODPA-M and PEPA (all manufactured by Manac), Ricacid MTA-10, Ricacid MTA-15, Ricacid TMTA, Ricacid TMEG-100, Ricacid TMEG-200, Ricacid TMEG-300, Ricacid TMEG-500, Ricacid TMEG-S, Ricacid TH, Ricacid HT-1A, Ricacid HH, Ricacid MH-700, Ricacid MT-500, Ricacid DSDA and Ricacid TDA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) PICLON B4400, EPICLON B650, and EPICLON B570 (all manufactured by both DIC Corporation).

  The acid anhydride having an alicyclic skeleton, a water additive of the acid anhydride, or a modified product of the acid anhydride is an acid anhydride having a polyalicyclic skeleton, a water additive of the acid anhydride, or the A modified product of an acid anhydride, or an acid anhydride having an alicyclic skeleton obtained by addition reaction of a terpene compound and maleic anhydride, a water additive of the acid anhydride, or a modified product of the acid anhydride It is preferable. By using these curing agents, the flexibility of the cured product and the moisture resistance and adhesion of the cured product are further increased.

  Examples of the acid anhydride having an alicyclic skeleton, a water addition of the acid anhydride, or a modified product of the acid anhydride include methyl nadic acid anhydride, acid anhydride having a dicyclopentadiene skeleton, and the acid anhydride And the like.

  Examples of commercially available acid anhydrides having the alicyclic skeleton, water additions of the acid anhydrides, or modified products of the acid anhydrides include Ricacid HNA and Ricacid HNA-100 (all of which are manufactured by Shin Nippon Rika Co., Ltd.) , And EpiCure YH306, EpiCure YH307, EpiCure YH308H, EpiCure YH309 (all of which are manufactured by Mitsubishi Chemical Corporation) and the like.

  (B) It is also preferred that the thermosetting agent is methyl nadic acid anhydride or trialkyltetrahydrophthalic anhydride. Use of methyl nadic anhydride or trialkyltetrahydrophthalic anhydride increases the water resistance of the cured product.

  Among the components contained in the thermosetting material, the content of the (B) thermosetting agent is preferably 0.1% in 100% by weight of the component excluding the solvent, (C) boron nitride particles and (D) insulating filler. % Or more, more preferably 1% by weight or more, preferably 40% by weight or less, more preferably 25% by weight or less. (B) It is easy to fully harden a thermosetting material as content of a thermosetting agent is more than the said minimum. (B) When content of a thermosetting agent is below the said upper limit, the excess (B) thermosetting agent which does not participate in hardening becomes difficult to generate | occur | produce. For this reason, the heat resistance and adhesiveness of hardened | cured material become still higher.

((C) Boron nitride particles)
From the viewpoint of effectively increasing heat dissipation and compressive strength, the ratio of the average particle size of (C) boron nitride particles to the average particle size of (D) insulating filler is preferably 0.01 or more, more preferably It is 0.2 or more, preferably 200 or less, more preferably 10 or less.

  Among the components contained in the thermosetting material, the content of (C) boron nitride particles is preferably 10% by volume or more, more preferably 30% in 100% by volume of the component excluding the solvent and 100% by volume of the cured product. % Or more, preferably 80% by volume or less, more preferably 75% by volume or less. (C) When the content of boron nitride particles is equal to or more than the above lower limit, heat dissipation and compressive strength are effectively increased. (C) It is easy to fully harden a thermosetting material as content of a boron nitride particle is below the said upper limit. (C) The heat conductivity and adhesiveness by hardened | cured material become still higher that content of a boron nitride particle is below the said upper limit.

  Among the components contained in the thermosetting material, the components excluding the solvent are thermosetting materials when the thermosetting material does not contain a solvent, and the solvents when the thermosetting material contains a solvent. It is a component excluding

  In the thermosetting material, the total content of (C) boron nitride particles in 100% by volume of the (C1) boron nitride particles is preferably 20% by volume or more, more preferably 50% by volume or more, and still more preferably. 60% by volume or more, particularly preferably 70% by volume or more, most preferably 80% by volume or more, and preferably 100% by volume or less. (C1) When the content of the aggregate is not less than the above lower limit, the heat dissipation and the compressive strength are effectively increased.

  Of the components contained in the thermosetting material, the total content of (C) boron nitride particles and (D) insulating filler is preferably 100% by volume of the component excluding the solvent and 100% by volume of the cured product. Is at least 10% by volume, more preferably at least 20% by volume, even more preferably at least 30% by volume, preferably at most 80% by volume, more preferably at most 75% by volume. When the total content of (C) boron nitride particles and (D) insulating filler is equal to or greater than the above lower limit, heat dissipation and compressive strength are effectively increased. When the total content of (C) boron nitride particles and (D) insulating filler is not more than the above upper limit, it is easy to sufficiently cure the thermosetting material. When the total content of (C) boron nitride particles and (D) insulating filler is not more than the above upper limit, the thermal conductivity and adhesiveness of the cured product are further enhanced.

  From the viewpoint of effectively increasing heat dissipation and compressive strength, (C) boron nitride particles are contained in 100% by volume of (C) boron nitride particles and (D) insulating filler in the thermosetting material. The amount is preferably 10% by volume or more, more preferably 20% by volume or more, still more preferably 50% by volume or more, and preferably 100% by volume or less. In the total 100 volume% of (C) boron nitride particles and (D) insulating filler in the thermosetting material, the content of (C) boron nitride particles may be less than 100 volume%. The volume% or less may be sufficient.

((D) Insulating filler that is not boron nitride particles)
(D) The insulating filler has insulating properties. (D) The insulating filler may be an organic filler or an inorganic filler. From the viewpoint of effectively improving heat dissipation, the (D) insulating filler is preferably an inorganic filler. From the viewpoint of effectively improving heat dissipation, the (D) insulating filler preferably has a thermal conductivity of 10 W / m · K or more. (D) It is preferable that the insulating filler is not an aggregate of particles. (D) As for an insulating filler, only 1 type may be used and 2 or more types may be used together. Insulation means that the volume resistivity of the filler is 10 ⁶ Ω · cm or more.

  From the viewpoint of further improving the heat dissipation of the cured product, the thermal conductivity of the (D) insulating filler is preferably 10 W / m · K or more, more preferably 15 W / m · K or more, and even more preferably 20 W / m ·. K or more. (D) The upper limit of the thermal conductivity of the insulating filler is not particularly limited. Inorganic fillers having a thermal conductivity of about 300 W / m · K are widely known, and inorganic fillers having a thermal conductivity of about 200 W / m · K are easily available.

  (D) The material of the insulating filler is not particularly limited. (D) The material of the insulating filler is preferably alumina, synthetic magnesite, aluminum nitride, silicon nitride, silicon carbide, zinc oxide or magnesium oxide, and alumina, aluminum nitride, silicon nitride, silicon carbide, zinc oxide or More preferably, it is magnesium oxide. Use of these preferable insulating fillers further enhances the heat dissipation of the cured product.

  (D) The insulating filler is preferably spherical particles or non-aggregated particles having an aspect ratio of more than 2. By using these insulating fillers, the heat dissipation of the cured product is further enhanced. The aspect ratio of the spherical particles is 2 or less. (D) The melt viscosity can be adjusted by the aspect ratio of the insulating filler. The melt viscosity can be lowered by using the (D) insulating filler having an aspect ratio of 2 or less, and the melt viscosity can be increased by using the (D) insulating filler having an aspect ratio exceeding 2.

  (D) The new Mohs hardness of the insulating filler material is preferably 12 or less, more preferably 9 or less. (D) When the new Mohs hardness of the insulating filler material is 9 or less, the workability of the cured product is further enhanced.

  From the viewpoint of further improving the workability of the cured product, the material of the (D) insulating filler is preferably synthetic magnesite, crystalline silica, zinc oxide, or magnesium oxide. The new Mohs hardness of these inorganic filler materials is 9 or less.

  From the viewpoint of effectively improving heat dissipation, the average particle size of the (D) insulating filler is preferably 1 μm or more, and preferably 100 μm or less. When the average particle size is not less than the above lower limit, (D) the insulating filler can be easily filled at a high density. When the average particle size is not more than the above upper limit, the withstand voltage of the cured product is further increased.

  The “average particle size” is an average particle size obtained from a particle size distribution measurement result in a volume average measured by a dry laser diffraction particle size distribution measuring apparatus.

  Among the components contained in the thermosetting material, the content of the (D) insulating filler is preferably 5% by volume or more, more preferably 10% in 100% by volume of the component excluding the solvent and 100% by volume of the cured product. % Or more, preferably 75% by volume or less, more preferably 65% by volume or less. (D) The heat dissipation of hardened | cured material becomes high effectively that content of an insulating filler is more than the said minimum and below the said upper limit.

(Other ingredients)
The said thermosetting material may contain the other component generally used for thermosetting compositions and thermosetting sheets, such as a dispersing agent, a chelating agent, antioxidant, besides the component mentioned above.

(Other details of thermosetting materials and cured products)
The thermosetting material may be a thermosetting paste or a thermosetting sheet. A cured product can be obtained by curing the thermosetting material. This hardened | cured material is a hardened | cured material of a thermosetting material, and is formed with the thermosetting material.

  FIG. 1 is a cross-sectional view schematically showing a cured product of a thermosetting material according to an embodiment of the present invention. In FIG. 1, the actual size and thickness are different for convenience of illustration.

  The cured product 1 shown in FIG. 1 includes a cured product part 11, an aggregate 12 of boron nitride particles, and an insulating filler 13. The insulating filler 13 is not an aggregate of boron nitride particles. In FIG. 1, the aggregate 12 of boron nitride particles is hatched extending from the upper left to the lower right. In FIG. 1, the insulating filler 13 is hatched with a line extending from the upper right to the lower left. In FIG. 1, an aggregate 12 of boron nitride particles is shown schematically.

  The hardened | cured material part 11 is a part which the thermosetting component containing a thermosetting compound and a thermosetting agent hardened | cured, and is obtained by hardening a thermosetting component.

  The said thermosetting material and the said hardened | cured material can be used for various uses as which heat dissipation etc. are calculated | required. The cured product is used by being disposed between a heat generating component and a heat radiating component, for example, in an electronic device.

  Hereinafter, the present invention will be clarified by giving specific examples and comparative examples of the present invention. The present invention is not limited to the following examples.

(A1) Thermosetting compound:
(1) Bisphenol A type epoxy monomer (“YD-127” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.)
(2) Naphthalene skeleton-containing epoxy monomer (“HP-4032” manufactured by DIC)
(3) Biphenyl skeleton-containing epoxy monomer ("YX4000H" manufactured by Mitsubishi Chemical Corporation)
(4) Bifunctional glycidylamine (“EP-3950S” manufactured by ADEKA)

(A2) Thermosetting compound:
(1) Bisphenol A type phenoxy resin ("jER1256" manufactured by Mitsubishi Chemical Corporation)
(2) Epoxy group-containing styrene resin ("Marproof G-1010S" manufactured by NOF Corporation)

(B) Thermosetting agent:
(1) Amine curing agent (“DD” manufactured by Nippon Carbide)
(2) Isocyanur-modified solid dispersion type imidazole (“2MZA-PW” manufactured by Shikoku Chemicals)
(3) Liquid phenol curing agent (“MEH-8000H” manufactured by Meiwa Kasei Co., Ltd.)

(C) Boron nitride particles:
(1) Boron nitride aggregated particles 1
(2) Boron nitride agglomerated particles 2
(3) Boron nitride agglomerated particles 3
(4) Boron nitride aggregated particles 4

Preparation of boron nitride aggregated particles 1:
Boron nitride primary particles having an average major axis of 7.3 μm and an aspect ratio of 12.9 are aggregated to an average particle size of 60 μm by a spray drying method, and epoxy silane coupling is 1% by weight based on the weight of boron nitride. Surface treatment was performed with an agent (“KBE403” manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare boron nitride aggregated particles 1. The obtained boron nitride aggregated particles 1 had an average aspect ratio of 1.2.

Preparation of boron nitride aggregated particles 2:
Boron nitride primary particles having an average major axis of 3.3 μm and an aspect ratio of 12.7 are aggregated to an average particle size of 70 μm by a spray drying method, and epoxy silane coupling is 1% by weight with respect to the weight of boron nitride. Surface treatment was performed with an agent (“KBE403” manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare boron nitride aggregated particles 2. The obtained boron nitride aggregated particles 2 had an aspect ratio of 1.1.

Production of boron nitride aggregated particles 3:
Boron nitride aggregated particles 3 were prepared by aggregating primary particles of boron nitride having an average major axis of 7.3 μm and an aspect ratio of 12.9 to an average particle size of 60 μm by spray drying. The obtained boron nitride aggregated particles 3 had an average aspect ratio of 1.2.

Production of boron nitride aggregated particles 4:
Boron nitride primary particles having an average major axis of 5.5 μm and an aspect ratio of 14.0 were aggregated so as to have an average particle size of 40 μm by a spray drying method, thereby producing boron nitride aggregated particles 4. The obtained boron nitride aggregated particles 4 had an aspect ratio of 6.

(E) Dispersant:
(1) Acrylic dispersant (“Disperbyk-2070” manufactured by Big Chemie Japan)

(Examples 1-4, Comparative Examples 1-3)
Production of thermosetting materials:
Using a homodisper type stirrer, each raw material was blended and kneaded in the proportions shown in Table 1 below (the blending unit is parts by weight) to prepare a thermosetting composition. During kneading, when the solid content was large and the homodisper type stirrer was difficult to rotate, it was appropriately diluted with a solvent (methyl ethyl ketone).

  Next, the obtained thermosetting composition was applied on a release polyethylene terephthalate (PET) film so as to have a thickness of 200 μm, dried in an oven at 50 ° C. for 10 minutes, and then on the release PET film. A thermosetting sheet (thermosetting material, B-staged thermosetting material) was prepared. In this way, a multilayer sheet of a release PET film and a thermosetting sheet was obtained. In addition, the solvent was not detected from the said thermosetting sheet.

(Evaluation)
<Minimum melt viscosity>
A multilayer sheet having a size of 25 mmΦ was cut out from the obtained multilayer sheet, and the release PET film was peeled off from the thermosetting sheet to obtain a measurement sample of the thermosetting sheet (thermosetting material). A measurement sample is sandwiched between a glass plate and a parallel plate (diameter 20 mm) of a rheometer (Rheologicala “DynAlyser”), and the heating rate is 5 ° C./min from 25 ° C. to 200 ° C. under the conditions of frequency 1 Hz and strain 1%. The change in the melt viscosity of the thermosetting sheet was measured by heating at. The minimum value of the melt viscosity of the measurement result is the minimum melt viscosity. In Examples 1 to 4 and Comparative Examples 1 to 3, the thermosetting sheet was cured after heating to 200 ° C.

<Thermal conductivity>
Production of laminate:
In the obtained multilayer sheet, the release PET film was peeled off from the thermosetting sheet to prepare two thermosetting sheets (thermosetting materials) having a thickness of 200 μm. Two thermosetting sheets with a thickness of 200 μm are stacked, sandwiched between two copper foils with a thickness of 105 μm, and heated from 40 ° C. to 200 ° C. at a heating rate of 5 ° C./min while pressing at a pressure of 6 MPa. Furthermore, the laminated body was produced by hold | maintaining at 200 degreeC for 2 hours.

  After the obtained laminate was cut into 1 cm square, carbon black spray was applied to both sides, and the thermal conductivity was measured. The thermal conductivity was measured by a laser flash method using “LFA447 Nanoflash” manufactured by NETZSCH Co. The thermal conductivity in Table 1 is a relative value with the value of Comparative Example 1 being 1.00.

<Void>
The cross section of the obtained laminate was processed with a cross section polisher and observed with a scanning electron microscope (SEM) to confirm the presence or absence of voids. The SEM observation conditions were a reflected electron mode, an acceleration voltage of 10 kV, an emission current of 20 μA, and a magnification of 1000 times. Voids were determined according to the following criteria.

[Void judgment criteria]
○: No void of 5 μm or more ×: There is a void of 5 μm or more

<Dielectric breakdown voltage>
An electrode was produced by etching the copper foil in the obtained laminate, and a test sample was obtained. An AC voltage was applied to the test sample in the oil bath, and a voltage at which a current of 10 mA or more flowed through the test sample was defined as a dielectric breakdown voltage. The dielectric breakdown voltage was determined according to the following criteria.

[Criteria for dielectric breakdown voltage]
○: 60 kV / mm or more ×: less than 60 kV / mm

  The results are shown in Table 1 below.

DESCRIPTION OF SYMBOLS 1 ... Hardened | cured material 11 ... Hardened | cured material part (cured part of the thermosetting component)
12 ... Aggregates of boron nitride particles 13 ... Insulating filler

Claims (6)

A thermosetting compound, a thermosetting agent, and a plurality of boron nitride particles;
The boron nitride particles include an aggregate in which boron nitride particles are aggregated,
A thermosetting material having a minimum melt viscosity of 1 × 10 ³ Pa · s or more and 1 × 10 ⁴ Pa · s or less when the thermosetting material is heated from 25 ° C. until it is cured at a heating rate of 5 ° C./min. Sex material.   The thermosetting material according to claim 1, wherein an average aspect ratio of the aggregate is 1 or more and 5 or less.   The thermosetting material according to claim 1, wherein the thermosetting compound includes an epoxy compound.   The thermosetting material according to any one of claims 1 to 3, wherein the aggregate is a surface-treated product with a surface treatment agent.   The thermosetting material according to any one of claims 1 to 4, wherein a content of the boron nitride particles is 10% by volume or more and 80% by volume or less in 100% by volume of a component excluding a solvent.   The thermosetting material according to claim 1, which is a thermosetting sheet.

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