JP2021113268A - Thermosetting resin composition, heat radiation sheet material, and metal base substrate - Google Patents

Abstract

To provide a thermosetting resin composition having excellent thermal conductivity.SOLUTION: A thermosetting resin composition contains epoxy resin, and aggregate boron nitride particles surface-treated with a surface treatment agent containing a predetermined phosphorus compound.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermosetting resin composition, a heat radiating sheet material, and a metal base substrate.

So far, various developments have been made on thermosetting resin compositions. As a technique of this kind, for example, the technique described in Patent Document 1 is known. Patent Document 1 describes a resin composition containing boron nitride and an epoxy resin (claims of Patent Document 1 and the like).

JP-A-2019-167436

However, as a result of examination by the present inventor, it has been found that the resin composition described in Patent Document 1 has room for improvement in terms of thermal conductivity.

As a result of further studies, the present inventor has found that the thermal conductivity of the cured product of the thermosetting resin composition can be controlled by appropriately selecting the surface treatment of the aggregated boron nitride particles. As a result of further diligent research based on such findings, it was found that the thermal conductivity of the cured product of the thermosetting resin composition can be improved by using the aggregated boron nitride particles surface-treated with a predetermined phosphoric acid compound. The present invention has been completed.

According to the present invention
Epoxy resin and
Aggregated boron nitride particles surface-treated with a surface treatment agent,
A thermosetting resin composition comprising
The surface treatment agent contains a phosphorus compound represented by the following general formula A.
Thermosetting resin compositions are provided.
[General formula A]
XP (= O) (OR) ₂
(In the above general formula A, X is a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms, and R may be the same or different from each other, and represents a hydrogen atom or an alkyl group.)

Further, according to the present invention.
With the base material
Provided is a heat radiating sheet material comprising a resin layer made of the thermosetting resin composition provided on the base material.

Further, according to the present invention.
With a metal substrate
An insulating layer provided on the metal substrate and
It is provided with a metal layer provided on the insulating layer.
Provided is a metal base substrate in which the insulating layer is a resin layer made of the above thermosetting resin composition or a cured product of the resin layer.

According to the present invention, a thermosetting resin composition having excellent thermal conductivity, a heat radiating sheet material using the same, and a metal base substrate are provided.

It is sectional drawing which shows the structure of the metal base substrate which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate. Moreover, the figure is a schematic view and does not match the actual dimensional ratio.

The thermosetting resin composition of this embodiment is outlined.

The thermosetting resin composition includes an epoxy resin, aggregated boron nitride particles surface-treated with a surface treatment agent, and the aggregated boron nitride particles.
including. The surface treatment agent contains a phosphorus compound represented by the following general formula A.
[General formula A]
XP (= O) (OR) ₂
(In the above general formula A, X is a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms, and R may be the same or different from each other, and represents a hydrogen atom or an alkyl group.)

According to the findings of the present inventor, it has been found that the thermal conductivity of a cured product of a thermosetting resin composition can be improved by using aggregated boron nitride particles surface-treated with a predetermined phosphoric acid compound.

Although the detailed mechanism is not clear, the bonding of the phosphorus compound having the aromatic group X and the polar group OR to the particle surface enhances the familiarity of the aggregated boron nitride particles with the resin and the dispersibility in the resin composition. Therefore, it is considered that the effect of thermal conductivity due to the aggregated boron nitride particles can be further obtained. The phosphorus compound binds to the surface of the aggregated boron nitride granules by, for example, O of M (metal) -O (oxygen) of the inorganic oxide to form a bond by dehydration condensation, or with a functional group such as a hydroxyl group. Bonds may be formed by dehydration condensation.

The thermosetting resin composition of the present embodiment can be used as a heat radiating material for electric / electronic devices and the like. This heat radiating material can be used, for example, as a substrate material for mounting an electronic component.

As the electric / electronic device, for example, an ordinary semiconductor device (an electronic device having a semiconductor element as an electronic component), a power module (an electronic device having a power semiconductor element as an electronic component), or the like can be used. Power semiconductor devices are made from _{wide bandgap materials such as SiC, GaN, Ga 2} O ₃ , or diamond and are designed to be used at high voltage and high currents, so they are usually silicon. Since the amount of heat generated is larger than that of a chip (semiconductor element), it operates in a higher temperature environment. Power semiconductor devices are required to be used for a long time in a high temperature operating environment such as 200 ° C. or higher or 250 ° C. or higher. Specific examples of the power semiconductor element include a rectifier diode, a power transistor, a power MOSFET, an insulated gate bipolar transistor (IGBT), a thyristor, a gate turn-off thyristor (GTO), a triac, and the like.

According to the thermosetting resin composition of the present embodiment, it is possible to provide a heat radiating material that can be used for a power module.

Hereinafter, the thermosetting resin composition of the present embodiment will be described in detail.

The thermosetting resin composition contains an epoxy resin and aggregated boron nitride particles.

(Epoxy resin)
The epoxy resin is a compound having two or more epoxy groups in one molecule, and monomers, oligomers, and polymers in general can be used, and the molecular weight and molecular structure thereof are not particularly limited. These may be used alone or in combination of two or more.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, and bisphenol M type epoxy resin (4,4'-(1,3-phenylenediiso). Pridiene) bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene) bisphenol type epoxy resin), bisphenol Z type epoxy resin (4,4'-cyclohexy) Bisphenol type epoxy resin such as dienbisphenol type epoxy resin); phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol group methane type novolac type epoxy resin, tetraphenol group ethane type novolac type epoxy resin, condensed ring aromatic carbonization Novolak type epoxy resin such as novolak type epoxy resin having a hydrogen structure; biphenyl type epoxy resin; arylalkylene type epoxy resin such as xylylene type epoxy resin and biphenyl aralkyl type epoxy resin; naphthylene ether type epoxy resin, naphthol type epoxy resin, Naphthalene type epoxy resin such as naphthalenediol type epoxy resin, bifunctional to tetrafunctional epoxy type naphthalene resin, binaphthyl type epoxy resin, naphthalene aralkyl type epoxy resin; anthracene type epoxy resin; phenoxy type epoxy resin; dicyclopentadiene type epoxy resin; Norbornen type epoxy resin; Adamantane type epoxy resin; Fluorene type epoxy resin and the like can be mentioned. These may be used alone or in combination of two or more.

The lower limit of the epoxy resin content is, for example, 5% by mass or more, preferably 7% by mass or more, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. More preferably, it is 10% by mass or more. As a result, the handleability of the thermosetting resin composition can be improved. On the other hand, the upper limit of the epoxy resin content is, for example, 80% by mass or less, preferably 75% by mass or less, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. be. Further, the upper limit of the epoxy resin content may be, for example, 45% by mass or less. As a result, the heat dissipation property can be further improved.

In the present specification, in the thermosetting resin composition containing no filler, the "filler" is a heat conductive filler described later, an ordinary filler such as an inorganic filler or an organic filler, and inorganic nanoparticles used as a dispersion stabilizer. including. That is, the thermosetting resin composition containing no filler is composed of a resin component other than the filler, and examples of the resin component include epoxy resin, phenoxy resin, and cyanate resin.

The epoxy resin may include a liquid epoxy resin.
The liquid epoxy resin can exhibit the flexibility of the sheet when the thermosetting resin composition is B-staged.

As the liquid epoxy resin, an epoxy compound having two or more epoxy groups and being liquid at room temperature of 25 ° C. can be used. The viscosity of this liquid epoxy resin at 25 ° C. is, for example, 1 mPa · s to 8000 mPa · s, preferably 5 mPa · s to 6000 mPa · s, and more preferably 10 mPa · s to 5000 mPa · s. ..
In the present specification, "~" means that an upper limit value and a lower limit value are included unless otherwise specified.

The liquid epoxy resin may include, for example, one or more selected from the group consisting of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, alkyl diglycidyl ether and alicyclic epoxy. These may be used alone or in combination of two or more.

The epoxy equivalent of the liquid epoxy resin is, for example, 100 g / eq or more and 200 g / eq or less, preferably 105 g / eq or more and 190 g / eq or less, and more preferably 110 g / eq or more and 180 g / eq or less. .. As a result, the flexibility of the sheet when it is B-staged can be expressed.

The lower limit of the content of the liquid epoxy resin is, for example, 5% by mass or more, preferably 7% by mass or more, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. , More preferably 10% by mass or more. Thereby, the flexibility of the finally obtained sheet can be expressed. On the other hand, the upper limit of the content of the liquid epoxy resin is, for example, 60% by mass or less, preferably 55% by mass or less, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. It is more preferably 30% by mass or less. Thereby, heat resistance and heat dissipation can be ensured.

The thermosetting resin composition may or may not contain other thermosetting resins in addition to the epoxy resin.
Examples of other thermosetting resins include polyimide resins, benzoxazine resins, unsaturated polyester resins, phenol resins, melamine resins, silicone resins, bismaleimide resins, acrylic resins, and derivatives of these phenol derivatives. As these thermosetting resins, monomers, oligomers, and polymers having two or more reactive functional groups in one molecule can be used in general, and the molecular weight and molecular structure thereof are not particularly limited. These may be used alone or in combination of two or more.

The content of the thermosetting resin is preferably, for example, 0.1% by mass or more and 30% by mass or less, preferably 0.5% by mass or less, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. More preferably, it is by mass% or more and 15% by mass or less. When it is at least the above lower limit value, the curability is improved and it becomes easy to form the resin layer. When it is not more than the above upper limit value, the storage stability of the resin layer is further improved, and the thermal conductivity of the resin layer is further improved.

(Phenoxy resin)
The thermosetting resin composition may contain a phenoxy resin. Thereby, the bending resistance can be enhanced.
Examples of the phenoxy resin include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a naphthalene skeleton, a phenoxy resin having an anthracene skeleton, and a phenoxy resin having a biphenyl skeleton. Further, a phenoxy resin having a structure having a plurality of types of these skeletons can also be used. These may be used alone or in combination of two or more.

The phenoxy resin may contain a compound having a mesogen structure in the molecule. As a result, the thermal conductivity can be further increased.

The mesogen structure has, for example, a structure represented by the following general formula (1) or general formula (2).
−A ¹ −x−A ² − ・ ・ (1)
−x−A ¹ −x− ・ ・ (2)
In the above general formulas (1) and (2), A ¹ and A ² independently represent an aromatic group, a condensed aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and x Are each independently linked directly, or -O-, -C = C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH = N-,- The divalent linking group selected from the group consisting of CH = NN = CH-, -N = N- and -N (O) = N- is shown.

Here, A ¹ and A ² are independently each of a hydrocarbon group having 6 to 12 carbon atoms having a benzene ring, a hydrocarbon group having 10 to 20 carbon atoms having a naphthalene ring, and 12 to 12 carbon atoms having a biphenyl structure. 24 hydrocarbon groups, 12 to 36 carbon hydrocarbon groups having 3 or more benzene rings, 12 to 36 carbon hydrocarbon groups having condensed aromatic groups, alicyclic heterocycles with 4 to 36 carbon atoms It is preferably selected from the groups. A ¹ and A ² may be unsubstituted or a derivative having a substituent.

Specific examples of A ¹ and A ^{2 in} the mesogen structure include phenylene, biphenylene, naphthalene, anthracenylene, cyclohexyl, pyridyl, pyrimidyl, thiophenylene and the like. Further, these may be unsubstituted or derivatives having substituents such as an aliphatic hydrocarbon group, a halogen group, a cyano group and a nitro group.

Examples of x corresponding to the linking group (linking group) in the mesogen structure include direct bonding or -C = C-, -C≡C-, -CO-O-, -CO-NH-, -CH =. A divalent substituent selected from the group N−, −CH = N−N = CH−, −N = N− or −N (O) = N− is preferred.
Here, the direct bond means that A ¹ and A ² in the single bond or the mesogen structure are connected to each other to form a ring structure. For example, the structure represented by the general formula (1) may include a naphthalene structure.

The content of the phenoxy resin is, for example, 1% by mass to 30% by mass, preferably 5% by mass to 25% by mass, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. be.

(Cyanate resin)
The thermosetting resin composition may contain a cyanate resin.
By containing the cyanate resin, it is possible to reduce the linear expansion and improve the elastic modulus and rigidity of the cured product of the thermosetting resin composition. It is also possible to contribute to the improvement of heat resistance and moisture resistance of the obtained electronic device.

(Hardener)
The thermosetting resin composition may contain a curing agent, if necessary.
The curing agent is selected according to the type of the thermosetting resin, and is not particularly limited as long as it reacts with the thermosetting resin.

Examples of the curing agent include a phenol resin-based curing agent, an amine-based curing agent, an acid anhydride-based curing agent, and a mercaptan-based curing agent. These may be used alone or in combination of two or more.

Examples of the phenol resin-based curing agent include novolak-type phenol resins such as phenol novolac resin, cresol novolak resin, naphthol novolak resin, aminotriazine novolak resin, novolak resin, and trisphenylmethane-type phenol novolac resin; terpene-modified phenol resin, di. Modified phenol resins such as cyclopentadiene-modified phenol resins; phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton, aralkyl-type resins such as naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenols such as bisphenol A and bisphenol F. Compounds: Resol-type phenolic resins and the like can be mentioned, and these may be used alone or in combination of two or more. Among these, a novolak type phenol resin or a resol type phenol resin can be used from the viewpoint of improving the glass transition temperature and reducing the coefficient of linear expansion.

(Curing accelerator)
The thermosetting resin composition may contain a curing accelerator, if necessary.
The type and amount of the curing accelerator are not particularly limited, but an appropriate one can be selected from the viewpoints of reaction rate, reaction temperature, storage stability and the like.

Examples of the curing accelerator include imidazoles, organic phosphorus compounds, tertiary amines, phenol compounds, organic acids and the like. These may be used alone or in combination of two or more. From the viewpoint of the balance between fluidity and curability, a curing accelerator having latent properties such as a tetra-substituted phosphonium compound, a phosphobetaine compound, an adduct of a phosphine compound and a quinone compound, and an adduct of a phosphonium compound and a silane compound is used. You may use it. From the viewpoint of increasing heat resistance, nitrogen atom-containing compounds such as imidazoles may be used.

Examples of the imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-diethylimidazole, and 2-phenyl-4-methyl-5-hydroxyimidazole. , 2-Phenyl-4,5-dihydroxymethylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimerite and the like.

Examples of the tertiary amines include triethylamine, tributylamine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo (5,4,0) undecene-7 and the like.
Examples of the phenol compound include phenol, bisphenol A, nonylphenol, 2,2-bis (3-methyl-4-hydroxyphenyl) propane and the like.
Examples of the organic acid include acetic acid, benzoic acid, salicylic acid, p-toluenesulfonic acid and the like.

The content of the curing accelerator may be 0.01% by mass to 10% by mass, or 0.02% by mass to 8% by mass, based on 100% by mass of the total of the thermosetting resin and the curing agent. It may be 0.05% by mass to 5% by mass.

(Aggregated boron nitride particles)
The agglomerated boron nitride particles are one of the thermally conductive fillers, and include those whose surface is surface-treated with a surface treatment agent.
The agglomerated boron nitride particles may contain scaly boron nitride, agglomerated particles or a mixture of agglomerated particles and monodisperse particles. The scaly boron nitride may be granulated into granules. By using agglomerated particles of scaly boron nitride, the thermal conductivity can be further enhanced. The agglomerated particles may be sintered particles or non-sintered particles.

The particle size d50 at which the cumulative frequency of the aggregated boron nitride particles in the volume-based particle size distribution is 50% is, for example, 0.1 μm to 30 μm, preferably 0.2 μm to 28 μm, and more preferably 0.5 μm to 25 μm. By setting the value to the above lower limit or more, the viscosity or melt viscosity of the resin composition in varnish can be reduced. By setting it to the above upper limit value or less, the thermal conductivity can be improved.

For the particle size of the aggregated boron nitride particles, for example, a laser diffraction / scattering type particle size distribution measuring device or the like is used for a sample in which the aggregated boron nitride particles are dispersed in a pure water medium containing sodium hexametaphosphate as a dispersion stabilizer. Can be measured using.

The surface treatment agent contains a phosphorus compound represented by the following general formula A.
[General formula A]
XP (= O) (OR) ₂

In the above general formula A, X is a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms, and R may be the same or different from each other, and represents a hydrogen atom or an alkyl group. Substituents include, for example, carboxyl groups, alkyl groups, hydroxyl groups, amino groups and the like.

In the general formula A, the aromatic group having 6 to 20 carbon atoms may be a phenyl group.
In the general formula A, the alkyl group may be a linear or branched alkyl group having 1 to 4 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or t-butyl. Group etc. can be mentioned.

It is preferable that at least one, preferably two, of R in the general formula A are hydrogen atoms in one molecule of the phosphorus compound.

The surface treatment agent preferably contains, for example, a phosphorus compound in which the aromatic group in the general formula A is a phenyl group, and more preferably contains phenylphosphonic acid.

A method for surface-treating inorganic particles using the above-mentioned surface-treating agent will be described.
First, the above phosphorus compound is mixed with a solvent to prepare a solution-like surface treatment agent.
The lower limit of the concentration of the phosphorus compound in the surface treatment agent is, for example, 0.001 mol / L or more, preferably 0.005 mol / L or more, and more preferably 0.01 mol / L or more. Thereby, the thermal conductivity can be improved. On the other hand, the upper limit of the concentration of the phosphorus compound in the surface treatment agent is, for example, 1.0 mol / L or less, preferably 0.5 mol / L or less, and more preferably 0.3 mol / L or less. As a result, it is possible to prevent the resin component from becoming unfamiliar with the resin component.

Subsequently, the inorganic particles are introduced into the solution-like surface treatment agent. In this embodiment, aggregated boron nitride particles are used as the inorganic particles. The mixing ratio of the surface treatment agent and the inorganic particles can be appropriately changed, but may be, for example, 40:60 to 60:40, preferably about 50:50 in terms of volume.
In addition, powdery inorganic particles or a dispersion medium in which the inorganic particles are dispersed in a predetermined dispersion solvent may be introduced into a solution-like surface treatment agent.

Subsequently, the mixed solution of the surface treatment agent and the inorganic particles is stirred. As the stirring operation, a known method can be used, but for example, a method of rotating the container containing the mixed solution for about 2 to 20 hours may be used. The stirring may be performed at room temperature of 25 ° C., or may be heated to such an extent that the solvent does not volatilize.

The above solvent is not particularly limited as long as it dissolves a phosphorus compound, but for example, an organic solvent having a water-soluble group such as a hydroxy group may be used, and specifically, an alcohol solvent is used. You may.
Further, as the solvent, a solvent which is hard to volatilize under atmospheric pressure at 25 ° C. may be used, and for example, a solvent having a boiling point of 50 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher is preferable. The solvent may be a mixed solvent containing one or two or more.
Among these, 1-methoxy-2-propanol, ethanol and the like can be used from the viewpoint of solubility and non-volatility of the phosphorus compound.

If necessary, the mixed solution may be filtered, or the filtered residue after filtration may be washed. As the cleaning liquid, water, the solvent used, or the like may be used.

Then, the solvent remaining in the mixed solution or the filter residue is removed. As a method for removing the solvent, known means can be used, but vacuum drying, heat drying and the like are used.

The step of surface treatment as described above can include any of a drying treatment at room temperature, a drying treatment at room temperature and under reduced pressure, and a drying treatment at 25 ° C. to 50 ° C. and under reduced pressure.

Further, as an example of the surface treatment method, while rotating the inorganic particles in a Henshell mixer, a surface treatment agent in which a phosphorus compound is dissolved in ethanol (solvent) is gradually dropped therein to form the inorganic particles and the surface treatment agent. May be adopted, and the obtained mixture is dried in a mixer.

By the above surface treatment method, aggregated boron nitride particles (inorganic particles) surface-treated with a phosphorus compound can be obtained.

The phosphorus compound is chemically, physically, or both bonded to the surface of the aggregated boron nitride particles. That is, the surface-treated aggregated boron nitride particles are in a state in which at least a part of the surface thereof is covered with an organic layer made of a phosphorus compound.
At this time, it is presumed that the phosphorus compound bonded to the surface has an X group such as a phenyl group on the outside and an OR group such as a hydroxy group on the inside.

According to the idea of the present inventor, the detailed mechanism is not clear, but the presence of predetermined phenyl groups and hydroxy groups in the phosphorus compound makes the balance between hydrophobicity and hydrophilicity appropriate, and thus the resin composition. It is considered that the interfacial resistance between the aggregated boron nitride particles treated with the phosphoric acid compound and the mesogen-containing resin is reduced because the familiarity in the inside is further improved and the balance between the overlap of pi electrons and the hydrogen bonds is appropriate.

Further, the thermal conductivity in the thickness direction can be increased by using agglomerated particles of scaly boron nitride (aggregates of scaly filler). The detailed mechanism is not clear, but it is because a part of the scaly filler is crushed during press molding and an isotropic heat conduction path is formed without the agglomerates of the scaly filler oriented in one direction. Conceivable. In addition, by adopting a mixing method that enables dispersion while suppressing the disintegration of agglomerates of the scaly filler by using a planetary mixer or a homomixer, the isotropic heat conduction path as described above can be obtained. It is thought that it can be realized.

The thermosetting resin composition may contain a thermally conductive filler other than the aggregated boron nitride particles.
Other thermally conductive fillers can include, for example, highly thermally conductive inorganic particles having a thermal conductivity of 20 W / m · K or more. The highly thermally conductive inorganic particles can include, for example, at least one selected from alumina, aluminum nitride, silicon nitride, silicon carbide and magnesium oxide. These may be used alone or in combination of two or more.

The content of the aggregated boron nitride particles is 100% by mass to 400% by mass, preferably 150% by mass to 350% by mass, based on the resin component (100% by mass) of the thermosetting resin composition containing no filler. It is more preferably 200% by mass to 330% by mass. By setting it to the above lower limit value or more, the thermal conductivity can be improved. By setting the value to the upper limit or less, it is possible to suppress a decrease in processability.

(Dispersion stabilizer)
The thermosetting resin composition may contain a dispersion stabilizer.
By using a dispersion stabilizer, sedimentation of the thermally conductive filler can be suppressed. By adding a nano component as a dispersion stabilizer, for example, the viscosity of the varnish of the thermosetting resin composition is increased, so that the precipitation of the thermally conductive filler can be suppressed. It is considered that this makes it possible to uniformly disperse the filler, obtain a composite molded product without molding defects, and exhibit stable thermal conductivity.

The thermosetting resin composition may contain a silane coupling agent.
Thereby, the compatibility of the heat conductive filler in the thermosetting resin composition can be improved. The coupling agent may be added to the thermosetting resin composition, or may be used by treating the surface of the heat conductive filler.

Examples of the silane coupling agent include epoxy-based silane coupling agents, amino-based silane coupling agents, mercapto-based silane coupling agents, ureido-based silane coupling agents, cationic silane coupling agents, and titanate-based coupling agents. And one or more selected from the group consisting of silicone oil type coupling agents. These may be used alone or in combination of two or more.
Among these, as the functional group, a silane coupling agent having at least one or more of an epoxy group, an amino group, a mercapto group, a ureido group or a hydroxy group can be used. Further, from the viewpoint of improving the compatibility with the resin component, a silane coupling agent having a non-reactive phenyl group can be used.

Specific examples of the silane coupling agent having the above functional groups include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-. Glycydoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-) Aminoethyl) Aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptotriethoxysilane, 3-ureidopropyltriethoxysilane and the like can be mentioned. Examples of the silane coupling agent containing the phenyl group include 3-phenylaminopropyltrimethoxysilane, 3-phenylaminopropyltriethoxysilane, N-methylanilinopropyltrimethoxysilane, and N-methylanilinopropyltri. Ethoxysilane, 3-phenyliminopropyltrimethoxysilane, 3-phenyliminopropyltriethoxysilane, phenyltrimethoxylane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, etc. Can be mentioned.

The amount of the coupling agent added is preferably, for example, 0.05% by mass or more and 3% by mass or less, and particularly preferably 0.1% by mass or more and 2% by mass or less, based on 100% by mass of the heat conductive filler.

The thermosetting resin composition of the present embodiment may contain components other than those described above. Examples of other components include antioxidants and leveling agents.

As a method for producing the thermosetting resin composition of the present embodiment, for example, there are the following methods.
A resin varnish (varnish-like thermosetting resin composition) can be prepared by dissolving, mixing, and stirring each of the above components other than the filler in a solvent. For this mixing, various mixers such as an ultrasonic dispersion method, a high-pressure collision type dispersion method, a high-speed rotation dispersion method, a bead mill method, a high-speed shear dispersion method, and a rotation / revolution type dispersion method can be used.

The solvent is not particularly limited, and examples thereof include methyl ethyl ketone, methyl isobutyl ketone, propylene glycol monomethyl ether, and cyclohexanone.

Further, a thermosetting resin composition in a B-stage state can be obtained by adding a filler such as a heat conductive filler to the resin varnish and kneading it using a three-roll or the like. By adding at the time of kneading, the heat conductive filler can be more uniformly dispersed in the thermosetting resin, but the present invention is not limited to this. The thermally conductive filler may be added at the time of kneading, or may be added at the time of mixing the resin varnish. From the viewpoint of dispersibility, it is preferable to add, for example, nanoparticles dispersed in a predetermined solvent (nanoparticle dispersion liquid) to the resin varnish.

The characteristics of the thermosetting resin composition of the present embodiment will be described.

The upper limit of the viscosity of the thermosetting resin composition measured according to the following procedure is, for example, 1.8 Pa · s or less, preferably 1.5 Pa · s or less, and more preferably 1.0 Pa · s or less. As a result, in the heat conductive resin composition at the time of varnish, the agglomerated boron nitride particles and the resin become well-adapted. In addition, the handleability of the thermally conductive resin composition at the time of producing a film is improved. The lower limit of the viscosity of the thermosetting resin composition is not particularly limited, but may be, for example, 0.1 Pa · s or more.
(procedure)
A sample is prepared by mixing the solid content of the thermosetting resin composition with propylene glycol monomethyl ether at a solid content concentration of 60%.
The obtained sample is applied to a copper foil and dried at 120 ° C. for 12 minutes.
The viscosity of the dried sample is measured using a cone plate type viscometer under the conditions of 180 ° C. and rotation frequency: 94 rpm.

The thermosetting resin composition of the present embodiment can be used in various embodiments, and as an example, it can be used in the form of a sheet.

(Resin sheet)
The resin sheet of the present embodiment includes a carrier base material and a resin layer made of the above-mentioned thermosetting resin composition provided on the carrier base material.

The resin sheet can be obtained, for example, by subjecting a coating film (resin layer) obtained by applying a varnish-like thermosetting resin composition on a carrier substrate to a solvent removing treatment. The solvent content in the resin sheet can be 10% by weight or less based on the entire thermosetting resin composition. For example, the solvent removal treatment can be performed under the conditions of 80 ° C. to 150 ° C. for 1 minute to 30 minutes. This makes it possible to sufficiently remove the solvent while suppressing the progress of curing of the thermosetting resin composition.

The resin sheet (resin layer with a carrier base material) may have a roll-like shape that can be wound up, or a rectangular single-wafer shape. The surface of the resin film of the resin sheet may be exposed, for example, or may be covered with a protective film (cover film). As the protective film, a film having a known protective function can be used, but for example, a PET film may be used.

Further, in the present embodiment, as the carrier base material, for example, a polymer film or a metal foil can be used. The polymer film is not particularly limited, but for example, heat resistance of polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, release papers such as polycarbonate and silicone sheets, fluororesins and polyimide resins. Examples thereof include a thermoplastic resin sheet having the above. The metal foil is not particularly limited, and is, for example, copper and / or copper-based alloy, aluminum and / or aluminum-based alloy, iron and / or iron-based alloy, silver and / or silver-based alloy, gold and gold-based alloy. , Zinc and zinc alloys, nickel and nickel alloys, tin and tin alloys and the like. Of these, a sheet made of polyethylene terephthalate is most preferable because it is inexpensive and the peel strength can be easily adjusted. This makes it easy to peel off the carrier base material from the resin layer with the carrier base material with an appropriate strength.

(Resin substrate)
The resin substrate of the present embodiment includes an insulating layer made of a cured product of the thermosetting resin composition. This resin substrate can be used as a material for an element mounting substrate for mounting electronic components such as semiconductor elements and power semiconductors.

(Metal base substrate)
The metal base substrate 100 of this embodiment will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing an example of the configuration of the metal base substrate 100.
As shown in FIG. 1, the metal base substrate 100 can include a metal substrate 101, an insulating layer 102 provided on the metal substrate 101, and a metal layer 103 provided on the insulating layer 102. .. The insulating layer 102 can be composed of one selected from the group consisting of a resin layer made of the above thermosetting resin composition, a cured product of the thermosetting resin composition, and a laminated board. Each of these resin layers and laminated plates may be composed of a thermosetting resin composition in a B-stage state before the circuit processing of the metal layer 103, and after the circuit processing, it is cured. It may be a cured product.

The metal layer 103 is provided on the insulating layer 102 and is circuit-processed. Examples of the metal constituting the metal layer 103 include one or more selected from copper, copper alloy, aluminum, aluminum alloy, nickel, iron, tin and the like. Among these, the metal layer 103 is preferably a copper layer or an aluminum layer, and particularly preferably a copper layer. By using copper or aluminum, the circuit workability of the metal layer 103 can be improved. For the metal layer 103, a metal foil available in the form of a plate may be used, or a metal foil available in the form of a roll may be used.

The lower limit of the thickness of the metal layer 103 is, for example, 0.01 mm or more, preferably 0.10 mm or more, and more preferably 0.25 mm or more. If it is more than such a value, it is possible to suppress heat generation of the circuit pattern even in an application requiring a high current.
The upper limit of the thickness of the metal layer 103 is, for example, 2.0 mm or less, preferably 1.5 mm or less, and more preferably 1.0 mm or less. If it is less than such a numerical value, the circuit workability can be improved, and the thickness of the entire substrate can be reduced.

The metal substrate 101 has a role of dissipating heat accumulated in the metal base substrate 100. The metal substrate 101 is not particularly limited as long as it is a heat-dissipating metal substrate, but is, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate. A copper substrate or an aluminum substrate is preferable, and a copper substrate is more preferable. By using a copper substrate or an aluminum substrate, the heat dissipation of the metal substrate 101 can be improved.

The thickness of the metal substrate 101 can be appropriately set as long as the object of the present invention is not impaired.
The upper limit of the thickness of the metal substrate 101 is, for example, 20.0 mm or less, preferably 5.0 mm or less. By using the metal substrate 101 having a thickness equal to or less than this value, the thickness of the metal base substrate 100 as a whole can be reduced. Further, it is possible to improve the workability in the outer shape processing, the cutting process, and the like of the metal base substrate 100.
The lower limit of the thickness of the metal substrate 101 is, for example, 0.1 mm or more, preferably 1.0 mm or more, and more preferably 2.0 mm or more. By using the metal substrate 101 having a value equal to or higher than this value, the heat dissipation of the metal base substrate 100 as a whole can be improved.

In the present embodiment, the metal base substrate 100 can be used for various substrate applications, but since it is excellent in thermal conductivity and heat resistance, it can be used as a substrate for a power module used for a power module. ..
The metal base substrate 100 can have a metal layer 103 that has been circuit-processed by etching the pattern or the like. In the metal base substrate 100, a solder resist (not shown) may be formed on the outermost layer, and the connection electrode portion may be exposed so that electronic components can be mounted by exposure / development.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples.

(Procedure for producing granular boron nitride)
A commercially available boron carbide powder was put into a carbon crucible and subjected to nitriding treatment under a nitrogen atmosphere at 2000 ° C. for 10 hours.
Next, a commercially available diboron trioxide powder was added to the obtained boron nitride powder, and the mixture was mixed with a blender for 1 hour (boron nitride: diboron trioxide = 7: 3 (mass ratio)). The obtained mixture was put into a carbon crucible and calcined in a nitrogen atmosphere at 2000 ° C. for 10 hours to obtain granular boron nitride.

-Aggregated boron nitride particles 1: The granular boron nitride obtained above was used as it was.

-Aggregated Boron Nitride Particle 2: The granular boron nitride obtained above was surface-treated by the following procedure and used.
(surface treatment)
Phosphonic acid (manufactured by Nissan Chemical Industries, Ltd.) was mixed with a 1-methoxy-2-propanol solution (manufactured by Fuji Film Co., Ltd.) to prepare a surface treatment agent having a phenylphosphonic acid concentration of 0.01 mol / L.
The obtained surface treatment agent and the above-mentioned granular boron nitride were placed in a bottle, and the sealed bottle was rotated at room temperature of 25 ° C. for 12 hours to mix them. The obtained mixture was filtered, washed with 1-methoxy-2-propanol, and then dried under reduced pressure for 24 hours to obtain granular boron nitride surface-treated with a surface treatment agent.

-Aggregated Boron Nitride Particles 3: The granular boron nitride obtained above was surface-treated in the same manner as in the above procedure except that the concentration of phenylphosphonic acid was 0.1 mol / L.

For each of the obtained aggregated boron nitride particles 1 and 3, a temperature rise rate of 10 ° C./min under a dry nitrogen stream using a differential thermogravimetric simultaneous measuring device (TG / DTA6200 type manufactured by Seiko Instruments). Depending on the conditions, the weight change was confirmed by raising the temperature of the sample from 30 ° C. to 650 ° C.
As a result, the weight change was observed in the aggregated boron nitride particles 3 at around 350 ° C., but not in the aggregated boron nitride particles 31.

(Epoxy resin)
Epoxy resin 1: Bifunctional naphthalene type epoxy resin (liquid at 25 ° C, manufactured by DIC Corporation, HP-4032D)
-Epoxy resin 2: Trifunctional naphthalene type epoxy resin (manufactured by DIC Corporation, HP-4700)
-Epoxy resin 3: Bisphenol F type epoxy resin (liquid at 25 ° C, manufactured by DIC, EPICLON 830S)

(Phenoxy resin)
-Phenoxy resin 1: Linear phenoxy resin 1 obtained by the following synthesis procedure A
(Synthesis procedure A)
22.9 parts by weight of ester group-containing bisphenol (bifunctional phenol compound, with mesogen structure, manufactured by Ueno Pharmaceutical Co., Ltd., HQHBA) represented by the following chemical formula and tetramethylbiphenyl type epoxy resin (bifunctional epoxy) represented by the following chemical formula. The compound has a mesogen structure, and 72.4 parts by weight of YX4000) manufactured by Mitsubishi Chemical Co., Ltd., 0.1 parts by weight of triphenylphosphine (TPP), and 4.6 parts by weight of cyclohexanone are dropped into a reactor at 120 ° C. to The reaction was carried out at 150 ° C. while removing the solvent. After confirming that the target molecular weight was obtained by GPC, the reaction was stopped. A linear phenoxy resin 1 having a weight average molecular weight of 7800 (in terms of polystyrene refractive index) was obtained.

-Phenoxy resin 2: Phenoxy resin 2 obtained by the following synthesis procedure B
(Synthesis procedure B)
The above tetramethylbiphenyl type epoxy resin was changed to an epoxy resin (manufactured by Nittetsu Chemical & Materials Co., Ltd., TC-3200E), and the above ester group-containing bisphenol was changed to 2,7-dihirodoxynaphthalene. The reaction was carried out in the same manner as in the synthesis procedure A of No. 1 to obtain phenoxy 2 having a molecular weight of 4600.

・硬化促進剤２：フェノール化合物（液状フェノール、明和化成社製、ＭＥＨ−８０００）
（界面活性剤）
・界面活性剤１：シリコーン系界面活性剤（ＢＹＫ社製、ＢＹＫ−０６６ Ｎ） (Hardener)
・ Hardener 1: Dicyandiamide (amine-based hardener, manufactured by Tokyo Kasei Co., Ltd.)
(Cyanate resin)
-Cyanate resin 1: Cyanate resin (no mesogen structure, manufactured by Lonza Japan, PT-30)
(Curing accelerator)
-Curing accelerator 1: Curing accelerator represented by the following chemical formula

-Curing accelerator 2: Phenol compound (liquid phenol, manufactured by Meiwakasei Co., Ltd., MEH-8000)
(Surfactant)
-Surfactant 1: Silicone-based surfactant (manufactured by BYK, BYK-066 N)

<Preparation of thermosetting resin composition>
Epoxy resin, phenoxy resin, curing accelerator, and if necessary, curing agent and surfactant are added to the solvent cyclohexanone according to the blending ratio shown in Table 1, and the mixture is stirred to prepare a thermosetting resin composition. A solution was obtained. Next, the aggregated boron nitride particles were added to this solution and premixed, and then mixed with a rotation / revolution mixer to obtain a varnish-like thermosetting resin composition in which the aggregated boron nitride particles were uniformly dispersed.

The obtained thermosetting resin composition was evaluated for the following evaluation items.

(Thermal conductivity)
-Comparative Example 2, Example 3:
The obtained thermosetting resin composition varnish was applied onto a copper foil having a thickness of 18 μm and dried to prepare a copper foil with a resin layer. The resin layer of this copper foil was placed on top of each other so as to be sandwiched between different copper foils, and compression molding was performed at 180 ° C. for 90 minutes at 10 MPa to obtain a composite molded body having a length of 10 cm, a width of 10 cm, and a thickness of 0.2 mm. ..
-Examples 1 and 2, Comparative Example 1:
A composite molded product was obtained in the same manner as described above except that the molding conditions were 180 ° C., 20 minutes, 10 MPa, and then curing was performed at 180 ° C. for 3 hours.

-Specific gravity of composite molded product The specific gravity was measured in accordance with JIS K 6911 (general test method for thermosetting plastics). The test piece was cut out from the above composite molded product into a length of 3 cm, a width of 4 cm, and a thickness of 2 mm, the copper foil was removed, and the test piece was dried at 120 ° C. for 3 hours. The unit of specific gravity (SP) is g / cm ³ .

-Specific heat of the composite molded product The specific heat (Cp) of the obtained composite molded product was measured by the DSC method.

-Measurement of Thermal Conductivity of Composite Molded Body A test piece was obtained by cutting out a composite molded body having a diameter of 10 mm and a thickness of 0.2 mm for measurement in the thickness direction. Next, the thermal diffusivity (α) in the thickness direction of the plate-shaped test piece was measured by the laser flash method using the Xe flash analyzer TD-1RTV manufactured by ULVAC. The measurement was carried out under the condition of 25 ° C. in the air atmosphere.
For each of the composite molded bodies, the thermal conductivity was calculated from the obtained measured values of thermal diffusivity (α), specific heat (Cp), and specific gravity (SP) based on the following formula.
Thermal conductivity [W / m · K] = α [m ² / s] x Cp [J / kg · K] x Sp [g / cm ³ ]

(CTE: coefficient of linear expansion)
The composite molded product obtained above was cut into pieces having a length of 3 cm, a width of 0.5 cm, and a thickness of 2 mm, and the copper foil was removed and dried to obtain a cured heat conductive sheet (test piece). The coefficient of linear expansion of the obtained test piece was measured. Using a TMA (Thermal Mechanical Analyzer) test device (TMA / SS6100 manufactured by Seiko Instruments), the temperature rise rate is 5 ° C./min, the load is 0.05N, the tension mode is used, and the measurement temperature range is 30 to 320 ° C. Thermomechanical analysis (TMA) was measured for 2 cycles. From the obtained results, the average value (α1) of the linear expansion coefficient in the plane direction (XY direction) from 50 ° C. to 100 ° C. and the average value (XY direction) of the linear expansion coefficient in the plane direction (XY direction) from 240 ° C. to 270 ° C. α2) was calculated. The coefficient of linear expansion (ppm / ° C.) was the value of the second cycle.

(Tg: glass transition temperature)
The composite molded product obtained above was cut into 3 cm in length × 0.5 cm in width × 2 mm in thickness, the copper foil was removed, and dried to obtain a cured heat conductive sheet. Next, the glass transition temperature (° C.) of the obtained cured product was measured by a DMA (Dynamic Mechanical Analysis) test device (DMS6100 manufactured by Seiko Instruments Inc.) at a heating rate of 10 ° C./min, a wave number of 1 Hz, and a tension mode. Measured under conditions.

The thermosetting resin compositions of Examples 1 and 2 showed a result that the thermal conductivity was improved with respect to Comparative Example 1 and Example 3 with respect to Comparative Example 2. It was also found that the examples of Examples 1, 2 and 3 can reduce the coefficient of linear expansion as compared with the corresponding Comparative Examples. The thermosetting resin composition of such an example can be suitably used for a resin sheet as a heat radiating material.

100 Metal base substrate 101 Metal substrate 102 Insulation layer 103 Metal layer

Claims (11)

Epoxy resin and
Aggregated boron nitride particles surface-treated with a surface treatment agent,
A thermosetting resin composition comprising
The surface treatment agent contains a phosphorus compound represented by the following general formula A.
Thermosetting resin composition.
[General formula A]
XP (= O) (OR) ₂
(In the above general formula A, X is a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms, and R may be the same or different from each other, and represents a hydrogen atom or an alkyl group.) The thermosetting resin composition according to claim 1.
A thermosetting resin composition in which the surface treatment agent contains the phosphorus compound in which the aromatic group in the general formula A is a phenyl group. The thermosetting resin composition according to claim 1 or 2.
A thermosetting resin composition in which the surface treatment agent contains phenylphosphonic acid. The thermosetting resin composition according to any one of claims 1 to 3.
A thermosetting resin composition in which the agglomerated boron nitride particles contain scaly boron nitride, agglomerated particles or a mixture of agglomerated particles and monodisperse particles. The thermosetting resin composition according to any one of claims 1 to 4.
A thermosetting resin composition having a particle size d50 of the aggregated boron nitride particles at which the cumulative frequency in the volume-based particle size distribution is 50% is 0.1 μm or more and 30 μm or less. The thermosetting resin composition according to any one of claims 1 to 5.
The thermosetting resin composition contains 100% by mass or more and 400% by mass or less of the solid content of the thermosetting resin composition containing no filler. The thermosetting resin composition according to any one of claims 1 to 6.
A thermosetting resin composition having a viscosity measured according to the following procedure of 1.8 Pa · s or less.
(procedure)
A sample is prepared by mixing the solid content of the thermosetting resin composition with propylene glycol monomethyl ether at a solid content concentration of 60%.
The obtained sample is applied to a copper foil and dried at 120 ° C. for 12 minutes.
The viscosity of the dried sample is measured using a cone plate type viscometer under the conditions of 180 ° C. and rotation frequency: 94 rpm. The thermosetting resin composition according to any one of claims 1 to 7.
A thermosetting resin composition containing a curing agent. The thermosetting resin composition according to any one of claims 1 to 8.
A sheet-like thermosetting resin composition. With the base material
A heat-dissipating sheet material comprising a resin layer made of the thermosetting resin composition according to any one of claims 1 to 9 provided on the base material. With a metal substrate
An insulating layer provided on the metal substrate and
It is provided with a metal layer provided on the insulating layer.
A metal-based substrate in which the insulating layer is a resin layer composed of the thermosetting resin composition according to any one of claims 1 to 9, or a cured product of the resin layer.

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