JP2017128475A - Composite filler and thermosetting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite filler and a thermosetting material which can improve thermal conductivity.SOLUTION: The present invention provides a composite filler that comprises a plurality of boron nitride particles, and a silicon carbide binder binding the plurality of boron nitride particles, and also provides a thermosetting material that comprises a thermosetting compound having the composite filler added thereto. In the composite filler, an average spectrum ratio is 2 or less, an average particle diameter is 1-100 μm, an average compressive modulus of elasticity is 5000 N/mmin 10% compression, and 3000 N/mmin 30% compression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite filler containing boron nitride particles. The present invention also relates to a thermosetting material using the composite filler.

  In recent years, miniaturization and high performance of 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 are difficult to be multilayered, have poor workability, and are very expensive.

  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 diameter 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 thermally conductive filler containing composite particles. The composite particles include tabular boron nitride fine particles and a binder that binds and integrates the boron nitride fine particles. The composite particle includes a solid core portion composed of the boron nitride fine particles and the binder. In the core portion, the boron nitride fine particles are included in a non-oriented state. The binder is substantially composed of an inorganic substance. In the non-oriented state, when the cross section of the core portion is observed, the longest side of the fine particles and the longest longest side of the remaining fine particles excluding the fine particles are different from each other for each of the boron nitride fine particles. The state which extends along.

Japanese Patent Laid-Open No. 2015-10200 Japanese Patent Laid-Open No. 2015-6980 JP 2013-136658 A

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

  However, the conventional aggregates of boron nitride particles described in Patent Documents 1 to 3 have a limit in increasing the thermal conductivity. Aggregates of boron nitride particles that are more excellent in thermal conductivity can greatly expand the applications of the aggregates of boron nitride particles.

  The objective of this invention is providing the composite filler which can improve thermal conductivity. Another object of the present invention is to provide a thermosetting material using the composite filler.

  In a broad aspect of the present invention, a composite filler comprising a plurality of boron nitride particles and a silicon carbide binder that binds the plurality of boron nitride particles is provided.

  In a specific aspect of the composite filler according to the present invention, the average aspect ratio is 2 or less.

  On the specific situation with the composite filler which concerns on this invention, an average particle diameter is 1 micrometer or more and 100 micrometers or less.

In a specific aspect of the composite filler according to the present invention, the average compression modulus when compressed by 10% is 5000 N / mm ² or less, and the average compression modulus when compressed by 30% is 3000 N / mm ² or less. It is.

  In a specific aspect of the composite filler according to the present invention, a peak derived from β-SiC is observed at 2θ = 35.9 ° in powder X-ray diffraction measurement.

  In a specific aspect of the composite filler according to the present invention, the total pore volume is 10 cc / g or less.

  On the specific situation with the composite filler which concerns on this invention, content of the said silicon carbide binder is 0.5 volume% or more and 50 volume% or less.

  In a specific aspect of the composite filler according to the present invention, the average sphericity is 0.8 or more.

  According to a wide aspect of the present invention, there is provided a thermosetting material including a thermosetting compound, a thermosetting agent, and the composite filler described above.

  On the specific situation with the thermosetting material which concerns on this invention, the said thermosetting material contains the insulating filler which is not the said composite filler.

  On the specific situation with the thermosetting material which concerns on this invention, content of the said composite filler is 10 volume% or more and 85 volume% or less.

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

  Since the composite filler according to the present invention includes a plurality of boron nitride particles and a silicon carbide binder that binds the plurality of boron nitride particles, thermal conductivity can be improved.

FIG. 1 is a photograph taken by a scanning electron microscope of a composite filler according to one embodiment of the present invention. FIG. 2 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.

(Composite filler)
The composite filler according to the present invention includes a plurality of boron nitride particles and a silicon carbide (SiC) binder. The composite filler according to the present invention is an aggregate of boron nitride particles. In the composite filler according to the present invention, the silicon carbide binder binds a plurality of boron nitride particles.

  FIG. 1 is a photograph taken by a scanning electron microscope of the composite filler according to one embodiment of the present invention. The composite filler shown in FIG. 1 has the above configuration.

  In the composite filler, since heat conduction is performed through the binder, the binder plays a major role. When using a conventional inorganic binder (for example, silica, alumina), the thermal conductivity of the inorganic binder is much lower than that of boron nitride. It has a big impact. On the other hand, since silicon carbide, which is a binder in the present invention, has a thermal conductivity equal to or higher than that of boron nitride, the obtained composite filler has a higher thermal conductivity than a composite filler using a conventional binder. Can be realized.

  Furthermore, in the composite filler which concerns on this invention, when force, such as compression, is provided, it can be deform | transformed in the range by which an aggregate state is not collapsed. For this reason, film-forming property can be improved or damage to the application target can be prevented.

  Furthermore, in the composite filler according to the present invention, since the boron nitride particles are firmly bound by the silicon carbide binder, the mechanical strength of the composite filler is high, and deformation occurs when pressure such as pressing is applied. It is difficult to break up the agglomerates.

  The composite filler is obtained by dispersing boron nitride particles and a silicon carbide binder in a solvent to obtain a dispersion, and granulating the dispersion by a method such as spray drying or fluidized bed granulation. Then, it can manufacture by baking at high temperature.

  The precursor of the silicon carbide binder is not particularly limited, and specific examples include silicon carbide nanoparticles and sols thereof, compounds having silicon atoms and carbon atoms, and mixtures of silicon oxide and carbon. Can be mentioned.

  When silicon carbide nanoparticles are used, the particle size is preferably 1000 nm or less, more preferably 800 nm, and even more preferably 500 nm or less. Such silicon carbide nanoparticles may be particles that are surface-modified to prevent oxidation or to be dispersed in a solvent.

  The compound having a silicon atom and a carbon atom is preferably an organosilicon compound having a Si—C bond. Such an organosilicon compound is not particularly limited, and examples thereof include a compound represented by the following formula (1) and a compound represented by the formula (2).

R1 _x -Si- (OR2) _4-x (1)

  In said formula (1), R1 represents a C20 or less organic group, R2 represents a methyl group or an ethyl group, and x represents the integer of 0-3.

  In said formula (2), R represents a C10 or less organic group, and n represents an integer. y is preferably 0.01 or more, and preferably 0.5 or less. n is preferably 3 or more, and preferably 100 or less. R may represent a saturated organic group, may represent an unsaturated organic group, and preferably represents a saturated alkyl group or an unsaturated alkyl group. The compound represented by the above formula (2) may have both a saturated organic group and an unsaturated organic group as R in the above formula (2). The compound represented by the formula (2) preferably has an allyl group, and more preferably has an allyl group as R in the formula (2).

  The firing conditions are preferably 500 ° C. or higher, more preferably 800 ° C. or higher, preferably 2400 ° C. or lower, more preferably 2200 ° C. or lower.

  The boron nitride particles preferably have a scaly shape because the effects of the present invention are more excellent. In the boron nitride particles, the ratio of the average major axis to the average thickness is preferably 2 or more, more preferably 3 or more, preferably 200 or less, more preferably 100 or less.

  From the viewpoint of effectively increasing the thermal conductivity and controlling the compression modulus within an appropriate range, the average primary particle diameter of the plurality of boron nitride particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, preferably Is 10 μm or less, more preferably 5 μm or less.

  The average primary particle diameter of the boron nitride particles means the average particle diameter on the volume basis of the primary particles. The average primary particle diameter of the boron nitride particles can be measured using a “laser diffraction particle size distribution analyzer” manufactured by Horiba, Ltd.

From the viewpoint of effectively increasing thermal conductivity and effectively maintaining high thermal conductivity after compression, the average compression modulus (average 10% K value) when the composite filler is compressed by 10% is preferably 5000 N. / Mm ² or less, more preferably 4000 N / mm ² or less, and even more preferably 3500 N / mm ² or less. From the viewpoint of suppressing the collapse of the excessive aggregation state of the composite filler and further improving the handleability of the composite filler, the average 10% K value of the composite filler is preferably 100 N / mm ² or more, more preferably 200 N / mm ^2. More preferably, it is 300 N / mm ² or more.

From the viewpoint of effectively increasing thermal conductivity and effectively maintaining high thermal conductivity after compression, the average compression modulus (average 30% K value) when the composite filler is compressed by 30% is preferably 3000 N. / Mm ² or less, more preferably 2500 N / mm ² or less. From the viewpoint of suppressing the collapse of the excessive aggregated state of the composite filler and further improving the handleability of the composite filler, the average 30% K value of the composite filler is preferably 50 N / mm ² or more, more preferably 100 N / mm ^2. That's it.

  The 10% K value and 30% K value of the composite filler can be measured as follows.

  Using a micro-compression tester, the composite filler is compressed under a condition that a smooth tester end face of a cylinder (diameter 50 μm, made of diamond) is loaded at 25 ° C. and a maximum test load of 90 mN over 30 seconds. The load value (N) and compression displacement (mm) at this time are measured. From the measured value obtained, the compression elastic modulus can be obtained by the following formula. As the micro compression tester, for example, “Fischer Scope H-100” manufactured by Fischer is used.

K value (N / mm ² ) = (3/2 ^1/2 ) · F · S ⁻³ / ² · R ^−1/2
F: Load value when the composite filler is 10% or 30% compressively deformed (N)
S: Compression displacement (mm) when the composite filler is 10% or 30% compressively deformed
R: Radius of composite filler (mm)

  The average 10% K value and the average 30% K value are obtained by averaging the 10% K value and the 30% K value of a plurality of composite fillers. It is preferable to average the 10% K value and 30% K value of 50 arbitrarily selected composite fillers.

  From the viewpoint of effectively filling the composite filler and increasing the thermal conductivity, the average aspect ratio of the composite filler is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and still more preferably. 1.8 or less, particularly preferably 1.6 or less, and most preferably 1.5 or less.

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

  From the viewpoint of further enhancing dispersibility in the resin, stability over time, and thermal conductivity, the average particle size of the composite filler is preferably 1 μm or more, more preferably 5 μm or more, preferably 100 μm or less, more preferably 80 μm or less. It is.

  The average particle size of the composite filler can be determined by measuring the particle size on a volume basis by measuring the particle size distribution. The average particle diameter of the composite filler can be measured using a “laser diffraction type particle size distribution analyzer” manufactured by Horiba, Ltd. It is preferable to average the particle diameter of 50 arbitrarily selected composite fillers.

  From the viewpoint of effectively increasing thermal conductivity, the total pore volume of the composite filler is preferably 10 cc / g or less, more preferably 5 cc / g or less.

  The pore volume takes into account the volume of the entire pores contained in the composite filler.

  The total pore volume can be measured, for example, by a mercury porosimeter method using “Pore Master 60” manufactured by QUANTACHROME.

  From the viewpoint of effectively increasing the thermal conductivity, the content of the silicon carbide binder in 100% by volume of the composite filler is preferably 0.1% by volume or more, more preferably 0.5% by volume or more, and still more preferably. It is 1 volume% or more, preferably 50 volume% or less.

  From the viewpoint of effectively increasing thermal conductivity, the content of boron nitride particles in 100% by volume of the composite filler is preferably 10% by volume or more, more preferably 30% by volume or more, still more preferably 50% by volume or more, preferably Is 99.9% by volume or less, more preferably 99.5% by volume or less, and still more preferably 99% by volume or less.

  From the viewpoint of effectively increasing the thermal conductivity, the average sphericity of the composite filler is preferably 0.8 or more, more preferably 0.85 or more, and still more preferably 0.9 or more.

  The average sphericity is obtained by averaging the sphericity of a plurality of composite fillers. It is preferable to average the sphericity of 50 arbitrarily selected composite fillers.

  Examples of the method for producing the composite filler include a spray drying method and a fluidized bed granulation method. 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 making it possible to control the total pore volume lower and to produce a composite filler having a higher compression modulus, the ultrasonic nozzle method is preferred.

  In view of the effect of the present invention, it is preferable that a peak derived from β-SiC is observed at 2θ = 35.9 ° in the powder X-ray diffraction measurement.

(Thermosetting material)
The thermosetting material according to the present invention includes (A) a thermosetting compound, (B) a thermosetting agent, and (C) a composite filler.

  By adopting the composition containing the components (A) to (C), the heat dissipation of the cured product can be considerably enhanced.

  From the viewpoint of increasing mechanical strength and voltage resistance, the thermosetting material according to the present invention includes (A) a thermosetting compound, (B) a thermosetting agent, (C) a composite filler, and (D). It is preferable to include an insulating filler that is not a composite filler (simply described as (D) insulating filler).

  By adopting the composition containing the components (A) to (D), the heat dissipation property of the cured product can be considerably increased, and the mechanical strength and voltage resistance of the cured product can be increased. For example, by using together (A) thermosetting compound, (B) thermosetting agent, (C) composite filler, and (D) insulating filler, compared to the case where these are not used together, Heat dissipation, mechanical strength and voltage resistance are effectively increased. In the present invention, the effects of high heat dissipation, high mechanical strength, and high voltage resistance, which have been difficult to satisfy in the past, can be achieved at a high level.

  Hereinafter, components contained in the thermosetting material according to 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.

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

  Among the components contained in the thermosetting material, the content of the (A) thermosetting compound is preferably 10% by weight or more in 100% by weight of the component excluding the solvent, (C) composite filler and (D) insulating filler. More preferably, it is 20% by weight or more, preferably 90% by weight or less, 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 excluding the solvent, (C) composite filler, and (D) insulating filler are (C) composite filler and ( D) It is a component excluding the insulating filler, and when the thermosetting material contains a solvent, it is a component excluding the solvent, (C) the composite filler, and (D) the insulating filler.

(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 a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, and a 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, bisphenol F type, or 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, more preferably 1200 or less, still more preferably 600 or less, and particularly 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.

  Among the components contained in the thermosetting material, the content of the (A1) thermosetting compound is preferably 10% by weight or more in 100% by weight of the component excluding the solvent, (C) composite filler and (D) insulating filler. More preferably, it is 20% by weight or more, preferably 90% by weight or less, 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 a naphthalene skeleton, a fluorene skeleton, a biphenyl skeleton, an anthracene skeleton, a pyrene skeleton, a xanthene skeleton, an adamantane skeleton, and a 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. 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 or more in 100% by weight of the component excluding the solvent, (C) composite filler and (D) insulating filler. More preferably, it is 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) composite filler 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, and MEH-8015 (all of which are manufactured by Meiwa Kasei Co., Ltd.), YLH903 (manufactured by Mitsubishi Chemical Corporation), LA-7052, LA-7054, and 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.

  Of the components contained in the thermosetting material, the content of the (B) thermosetting agent is preferably 0.1% by weight in 100% by weight of the components excluding the solvent, (C) composite filler and (D) insulating filler. Above, 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) Composite filler)
(C) The composite filler is the composite filler described above, and includes a plurality of boron nitride particles and a silicon carbide binder.

  From the viewpoint of effectively increasing heat dissipation and mechanical strength, the ratio of the average particle diameter of (C) the composite filler to the average particle diameter of (D) the 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 the (C) composite filler is preferably 10% by volume or more, more preferably 20% by volume, in 100% by volume of the component excluding the solvent and in 100% by volume of the cured product. As mentioned above, Preferably it is 85 volume% or less, More preferably, it is 75 volume% or less. (C) When content of a composite filler is more than the said minimum, heat dissipation and mechanical strength become high effectively. (C) It is easy to fully harden a thermosetting material as content of a composite filler is below the said upper limit. (C) The heat conductivity and adhesiveness by hardened | cured material become still higher that content of a composite filler 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

  From the viewpoint of effectively increasing heat dissipation and mechanical strength, (D) insulation in 100% by volume of thermosetting material of the content of (C) composite filler in 100% by volume of thermosetting material The ratio to the filler content is preferably 0.001 or more, more preferably 0.02 or more, preferably 2 or less, more preferably 1 or less.

((D) Insulating filler that is not a composite filler)
(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, boron nitride, aluminum nitride, silicon nitride, silicon carbide, zinc oxide or magnesium oxide, alumina, boron nitride, aluminum nitride, silicon nitride, More preferred is silicon carbide, zinc oxide or 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.

  (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 boron nitride, 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 diameter of the (D) insulating filler is preferably 1 μm or more, and preferably 100 μm or less. When the average particle diameter 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 enhanced.

  The “average particle diameter” is an average particle diameter obtained from a volume average particle size distribution measurement result measured by a 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) When content of an insulating filler is more than the said minimum and below the said upper limit, the heat dissipation and mechanical strength of hardened | cured material will become high effectively.

(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. Each cured product is a cured product of a thermosetting material, and is formed of a thermosetting material.

  FIG. 2 is a cross-sectional view schematically showing a cured product of a thermosetting material according to an embodiment of the present invention. In FIG. 2, the actual size and thickness are different for convenience of illustration.

  The cured product 1 shown in FIG. 2 includes a cured product part 11, a composite filler 12, and an insulating filler 13. The insulating filler 13 is not a composite filler. In FIG. 2, the composite filler 12 is provided with diagonal lines extending from the upper left to the lower right. In FIG. 2, the insulating filler 13 is hatched with a line extending from the upper right to the lower left. In FIG. 2, the composite filler 12 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, mechanical strength, 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.

Example 1
<Production of composite filler>
The composite filler is produced by the following two steps of spheroidization and firing.

Spheroidizing process / aggregate production process:
100 g of boron nitride particles (“MBN-010T” manufactured by Mitsui Chemicals), 20 g of allyl hydride polycarbon silane (“SMP-10” manufactured by Starfire Systems), which is a precursor of silicon carbide, and methyl ethyl ketone (Wako Pure Chemical Industries, Ltd.) (Manufactured by MEK) 380 g was mixed and subjected to dispersion treatment with ultrasonic waves for 30 minutes to prepare a slurry for spraying.

  Next, the slurry for spraying is spray-dried at 100 ° C. using a spray drying apparatus (“B-290” manufactured by Büch) in which a two-fluid nozzle is set, thereby agglomerated particles (spherical shape) having an average particle diameter of 5 μm. Aggregated particles) were obtained.

Firing process:
The aggregated particles were baked in a nitrogen atmosphere at 1000 ° C. for 2 hours and further at 1500 ° C. for 2 hours to obtain a composite filler. By this firing process, the silicon carbide precursor was converted into β-type crystalline silicon carbide (in the X-ray diffraction measurement, a crystal diffraction peak derived from β-SiC appeared at 2θ = 35.9 degrees). At the same time, the formed β-type silicon carbide worked as a binder for the boron nitride particles, and a spherical BN—SiC composite filler was formed.

<Preparation of heat conductive sheet>
700 parts by weight of the obtained composite filler, 290 parts by weight of an epoxy resin (bisphenol A, “Epicoat 828US” manufactured by Mitsubishi Chemical Corporation), 10 parts by weight of a thermosetting agent (dicyandiamide), and 550 parts by weight of methyl ethyl ketone as a solvent are homodispers. Mix for 30 minutes with a stirrer. Thereafter, the solvent was evaporated and a resin composition was prepared by vacuum defoaming.

  The resin composition was applied on a release PET sheet (thickness 50 μm) to a thickness of 100 μm, dried in an oven at 90 ° C. for 10 minutes to form a thermosetting sheet, and a laminated sheet was obtained. . Thereafter, the release PET sheet was peeled off, and both surfaces of the thermosetting sheet were sandwiched between a copper foil and an aluminum plate, and a heat conductive sheet was produced by vacuum pressing under conditions of a temperature of 150 ° C. and a pressure of 4 MPa.

(Example 2)
A composite filler and a heat conductive sheet were produced in the same manner as in Example 1 except that the nozzle during spraying was changed from the conventional two-fluid nozzle to the ultrasonic nozzle.

(Comparative Example 1)
A composite filler and a heat conductive sheet were produced in the same manner as in Example 1 except that allyl hydride polycarbon silane was changed to alumina sol.

(Evaluation)
<Measurement of thermal conductivity>
The thermal conductivity was measured by a laser flash method using a measurement sample in which the heat conductive sheet was cut into 1 cm square and then sprayed with carbon black on both sides. The thermal conductivity in Table 1 is a relative value with the value of Comparative Example 1 being 1.0.

<Compressive modulus>
10% K value (10% average compression elastic modulus) and 30% K value (30% average compression elastic modulus) by the above-mentioned method using a micro compression tester (Fischer Scope H-100 manufactured by Fischer) Asked. In addition, the average of the measured value of several composite filler was calculated | required.

<Total pore volume>
The total pore volume of the composite filler was measured using a mercury porosimeter (“Pore Master 60” manufactured by QUANTACHROME).

  The results are shown in Table 1 below.

  In addition, about the composite filler obtained in the Example, the total pore volume in the whole pore was 10 cc / g or less.

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

Claims (12)

A plurality of boron nitride particles;
A composite filler comprising: a silicon carbide binder that binds a plurality of the boron nitride particles.   The composite filler according to claim 1, wherein the average aspect ratio is 2 or less.   The composite filler according to claim 1 or 2, wherein the average particle size is 1 µm or more and 100 µm or less. The average elastic modulus when compressed by 10% is 5000 N / mm ² or less,
The composite filler according to any one of claims 1 to 3, wherein an average compression elastic modulus when compressed by 30% is 3000 N / mm ² or less.   The composite filler according to any one of claims 1 to 4, wherein a peak derived from β-SiC is observed at 2θ = 35.9 ° in powder X-ray diffraction measurement.   The composite filler according to any one of claims 1 to 5, wherein the total pore volume is 10 cc / g or less.   The composite filler according to any one of claims 1 to 6, wherein a content of the silicon carbide binder is 0.5% by volume or more and 50% by volume or less.   The composite filler according to any one of claims 1 to 7, wherein the average sphericity is 0.8 or more. A thermosetting compound;
A thermosetting agent;
The thermosetting material containing the composite filler of any one of Claims 1-8.   The thermosetting material according to claim 9, comprising an insulating filler that is not the composite filler.   The thermosetting material according to claim 9 or 10, wherein the content of the composite filler is 10% by volume or more and 80% by volume or less.   The thermosetting material according to any one of claims 9 to 11, which is a thermosetting sheet.