JP7501105B2 - Resin-coated inorganic particles, thermosetting resin composition, semiconductor device, and method for producing resin-coated inorganic particles - Google Patents

Description

The present invention relates to resin-coated inorganic particles, a thermosetting resin composition, a semiconductor device, and a method for producing resin-coated inorganic particles.

Attempts have been made to modify resins or compounds with coupling agents to add various functions. Patent documents 1 to 7, for example, disclose bifunctional or higher polymerizable compounds modified with coupling agents. These documents state that the modified compounds can link inorganic particles together to improve heat dissipation.

Furthermore, various developments have been made in the field of heat dissipation and insulation materials. For example, the technology described in Patent Document 8 is known as this type of technology. Patent Document 8 describes a thermosetting resin composition using bisphenol A type epoxy resin, a phenolic curing agent, and boron nitride particles as a thermally conductive filler as a heat dissipation and insulation material for constituting electric and electronic devices (Table 1 of Patent Document 8).
Furthermore, Patent Document 9 describes an encapsulating resin composition containing a biphenyl-type epoxy resin represented by a specific general formula.

International Publication No. 2016/031888 International Publication No. 2017/150586 International Publication No. 2017/150587 International Publication No. 2017/150588 International Publication No. 2017/150589 International Publication No. 2018/0181838 JP 2019-137801 A JP 2015-193504 A JP 2019-151691 A

However, even when inorganic particles were treated with a bifunctional or higher polymerizable compound modified with a coupling agent as described in Patent Documents 1 to 7, the improvement in heat dissipation was not sufficient.

The bisphenol A type epoxy resin described in Patent Document 8 leaves room for improvement in terms of thermal conductivity. However, Patent Document 9 does not mention thermal conductivity.

The inventors discovered that thermal conductivity can be improved by coating inorganic particles with a resin having a specific structure, and thus completed the present invention. That is, the present invention can be described as follows.

According to the present invention,
(a) inorganic particles;
(b) a resin that coats the surfaces of the inorganic particles (a);
It consists of:
Resin (b) is a resin-coated inorganic particle comprising a resin (b1) having two or more mesogenic skeletons in the molecule.

According to the present invention,
The resin-coated inorganic particles;
Epoxy resin,
A thermosetting resin (excluding the epoxy resin),
A thermosetting resin composition comprising:

According to the present invention,
There is provided a semiconductor device in which a semiconductor element is encapsulated with a cured product of the thermosetting resin composition.

According to the present invention,
Dispersing inorganic particles (a) in an organic solvent;
mixing the obtained dispersion with a resin (b) containing a resin (b1) having two or more mesogenic skeletons in the molecule;
a step of mixing the mixture with the dispersion to coat the surfaces of the inorganic particles (a) with a resin (b) to prepare a thermosetting resin composition containing resin-coated inorganic particles;
The present invention provides a method for producing resin-coated inorganic particles, comprising the steps of:

According to the present invention,
A step of dispersing a resin (b) containing a resin (b1) having two or more mesogenic skeletons in a molecule in an organic solvent to obtain a dispersion;
A step of mixing inorganic particles (a), an epoxy resin, a thermosetting resin (excluding the epoxy resin), and the dispersion liquid to obtain a mixture;
heating and kneading the mixture;
The present invention provides a method for producing a thermosetting resin composition, comprising:

The resin-coated inorganic particles of the present invention have excellent thermal conductivity because the inorganic particle surface is coated with a resin having a specific structure. Furthermore, a thermosetting resin composition containing the resin-coated inorganic particles can provide a semiconductor device having a resin cured product having excellent thermal conductivity and an encapsulant made of the resin cured product.

1 is a cross-sectional view showing an example of a semiconductor device according to an embodiment of the present invention. 1 is a cross-sectional view showing an example of a semiconductor device according to an embodiment of the present invention. 1 is a cross-sectional view showing a configuration of a metal base substrate according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. In all drawings, similar components are given similar reference symbols and descriptions are omitted where appropriate. In addition, "~" indicates "above" to "below" unless otherwise specified.

The resin-coated inorganic particles of this embodiment are composed of inorganic particles (a) and a resin (b) that coats the surfaces of the inorganic particles (a), and the resin (b) includes a resin (b1) having two or more mesogenic skeletons in the molecule.
The term "coated" includes not only the case where the entire surface of the inorganic particle (a) is covered with the resin (b), but also the state where the resin (b) is attached to only a part of the surface.

[Inorganic particles (a)]
In this embodiment, the inorganic particles (a) can be selected from conventionally known inorganic particles as long as they have thermal conductivity.

The inorganic particles (a) may be, for example, silica such as fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica, and finely powdered silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide, and one or more selected from these may be used.

In applications requiring better heat dissipation, for example, highly thermally conductive inorganic particles having a thermal conductivity of 20 W/m·K or more can be included. Examples of highly thermally conductive inorganic particles include alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide, and one or more types selected from these can be used.

The thermally conductive filler, boron nitride, may contain monodisperse particles, agglomerated particles, or a mixture thereof, of scaly boron nitride. The scaly boron nitride may be granulated. By using agglomerated particles of scaly boron nitride, the thermal conductivity can be further increased. The agglomerated particles may be sintered or non-sintered.

From the viewpoint of the effects of the present invention, the average particle size of the inorganic particles (a) is preferably 0.1 μm or more and 100 μm or less, more preferably 0.2 μm or more and 75 μm or less, and particularly preferably 0.3 μm or more and 50 μm or less.
As the inorganic particles (a), two types of inorganic particles (a1) and (a2) having different average particle sizes can be used.
The average particle size of the inorganic particles (a1) is preferably 0.1 μm or more and 3 μm or less, more preferably 0.2 μm or more and 2 μm or less, and particularly preferably 0.3 μm or more and 1 μm or less.
The average particle size of the inorganic particles (a2) is preferably 5 μm or more and 100 μm or less, more preferably 7 μm or more and 75 μm or less, and particularly preferably 8 μm or more and 50 μm or less.

From the viewpoint of the effects of the present invention, the specific surface area of the inorganic particles (a) is preferably 0.1 m ² /g or more and 5 m ² /g or less, more preferably 0.2 m ² /g or more and 3 m ² /g or less, and particularly preferably 0.3 m ² /g or more and 0.5 m ² /g or less. The specific surface area can be measured by the BET method.

[Resin (b)]
The resin (b) that coats the surfaces of the inorganic particles (a) contains a resin (b1) that has two or more mesogenic skeletons in the molecule.

The mesogenic skeleton may be any skeleton that facilitates liquid crystallinity or crystallinity through intermolecular interactions. The mesogenic skeleton preferably includes a conjugated structure. Specific examples of the mesogenic skeleton include a biphenyl skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, a stilbene skeleton, a naphthalene skeleton, an anthracene skeleton, and a phenanthrene skeleton.
The resin (b1) preferably contains a biphenyl skeleton and/or a phenylbenzoate skeleton as a mesogenic skeleton.

The resin (b1) is not particularly limited, and any conventionally known resin can be used as long as it has a structure containing two or more mesogenic skeletons in the molecule. For example, a phenoxy resin (A) containing two or more mesogenic skeletons in the molecule is preferably used. From the viewpoint of the effects of the present invention, the phenoxy resin (A) preferably contains a phenylene skeleton, and a mesogenic skeleton containing a phenylene skeleton is preferably selected.

The phenoxy resin (A) preferably contains a structural unit derived from a phenol compound and a structural unit derived from an epoxy compound.
Examples of the phenol compound include hydroquinone (compound name: 1,4-benzenediol), 4-hydroxyphenyl 4-hydroxybenzoate, 1,4-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 4,4'-biphenol, 3,3',5,5'-tetramethyl-4,4'-diol, and bis(4-hydroxyphenyl)sulfone. One or more selected from these can be used.

Examples of epoxy compounds include 3,3',5,5'-tetramethyl-4,4'-bis(glycidyloxy)-1,1'-biphenyl, 4,4'-biphenyl diglycidyl ether, 1,6-bis(glycidyloxy)naphthalene, etc., and one or more selected from these can be used.

The structural unit derived from the epoxy compound is preferably modified with a silane coupling agent. This allows the phenoxy resin (A) to have better adhesion to inorganic particles, and the phenoxy resin (A) is stably present on the surface of the inorganic particles. Therefore, for example, by coating inorganic particles that require heat dissipation, the heat dissipation properties of the phenoxy resin (A) can be imparted, and thermal conductivity can be further improved. Furthermore, by adding inorganic particles coated with the phenoxy resin (A) to a thermosetting resin composition, the compatibility between the inorganic particles and other resin components in the composition is improved, the thermal resistance at the interface is suppressed, and the thermal conductivity of the inorganic particles can be more effectively exhibited, so that heat from semiconductor elements, substrates, etc. can be suitably dissipated. For example, it can be suitably used in applications requiring heat dissipation, such as semiconductor encapsulants, thermally conductive resin sheets, resin substrates, and metal-based substrates.

An example of a structural unit derived from a phenol compound is a group represented by the following general formula (1-1):

In the above general formula (1-1), Q ¹ to Q ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.
In view of the effects of the present invention, Q ¹ to Q ⁴ are preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and particularly preferably a hydrogen atom.
m is 0 or 1. * indicates a bond.

An example of a structural unit derived from an epoxy compound is a group modified with a silane coupling agent, as represented by the following general formula (1-2):

In the above general formula (1-2), R ¹ to R ⁴ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an allyl group.

From the viewpoint of the effects of the present invention, R ¹ to R ⁴ are preferably an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an allyl group, more preferably an alkyl group having 1 to 6 carbon atoms, and particularly preferably an alkyl group having 1 to 3 carbon atoms.
* indicates a bond.
^X1 and ^X2 are each a hydrogen atom or a group represented by the following general formula (2), and at least one of ^X1 and ^X2 is a group represented by the following general formula (2).

In the general formula (2), Z represents an alkylene group having 2 to 10 carbon atoms.
From the viewpoint of the effects of the present invention, Z is preferably an alkylene group having 2 to 8 carbon atoms, more preferably an alkylene group having 2 to 5 carbon atoms, and particularly preferably an alkylene group having 2 to 3 carbon atoms.
R ⁵ to R ⁷ each independently represent an alkoxy group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms, and at least one of them is an alkoxy group having 1 to 3 carbon atoms.

From the viewpoint of the effects of the present invention, it is preferable that at least two of R ⁵ to R ⁷ are alkoxy groups having 1 to 3 carbon atoms, and it is more preferable that all of them are alkoxy groups having 1 to 3 carbon atoms.

The phenoxy resin (A) of this embodiment is provided with a group represented by general formula (2) in at least one of ^X1 and ^X2 , and is bonded to the surface of the inorganic particle (a) via a Si-O bond, improving adhesion with the inorganic particle. Therefore, by coating the inorganic particle with the phenoxy resin (A), the heat dissipation property of the phenoxy resin (A) is imparted, and the thermal conductivity can be further improved, and the compatibility between the inorganic particle and other resin components is improved, allowing the thermal conductivity of the inorganic particle to be more effectively exhibited.

Specifically, the phenoxy resin (A) of the present embodiment has, in its structure,
It can contain at least one selected from a repeating unit a in which ^X1 and ^X2 are both a group represented by general formula (2), and a repeating unit b in which ^X1 and ^X2 are a combination of a group represented by general formula (2) and a hydrogen atom.
The phenoxy resin (A) of the present embodiment may partially contain a repeating unit c in which X ¹ and X ² are both hydrogen atoms.

The phenoxy resin (A) of this embodiment preferably has two types of structures selected from the structure represented by the following general formula (3) and the structure represented by the following general formula (4) at both ends.

In formula (3), R ¹ to R ⁴ have the same meanings as in formula (1-2), Z and R ⁵ to R ⁷ have the same meanings as in formula (2), and * represents a bond.

In formula (4), R ¹ to R ⁴ have the same meaning as in formula (1-2). * represents a bond.

From the viewpoint of the effects of the present invention, the phenoxy resin (A) of this embodiment preferably has a structure represented by the general formula (3) at at least one of its two terminals, and more preferably has a structure represented by the general formula (3) at both terminals.

The phenoxy resin (A) of this embodiment has a structure represented by the general formula (3) and bonds to the surface of the inorganic particles (a) via Si-O bonds, improving adhesion to the inorganic particles. Therefore, by coating the inorganic particles with the phenoxy resin (A), the heat dissipation properties of the phenoxy resin (A) are imparted, further improving thermal conductivity, and the compatibility between the inorganic particles and other resin components is improved, allowing the thermal conductivity of the inorganic particles to be more effectively exhibited.

In this embodiment, the phenoxy resin (A) preferably has a SiR _n (OR) _m group (m is an integer of 1 to 3, and n+m=3; R represents an organic group), specifically, the phenoxy resin (A) preferably has a group represented by -SiR ⁵ R ⁶ R ⁷ on its side chains (X ¹ and X ² ) and/or ends, which bonds to the surfaces of the inorganic particles (a) via Si-O bonds, improving adhesion to the inorganic particles. The Si atom of the Si-O bond is bonded to the side chains and/or ends of the phenoxy resin (A).

The phenoxy resin (A) of this embodiment preferably contains, for example, a repeating unit represented by the following general formula (1). By having this structure, the phenoxy resin (A) has superior thermal conductivity.

In formula (1), R ¹ to R ⁴ , X ¹ and X ² are the same as those in formula (1-2), m and Q ¹ to Q ⁴ are the same as those in formula (1-1), and * is a bond.

The phenoxy resin (A) of this embodiment preferably has two types of structures selected from the structure represented by the above general formula (3) and/or the structure represented by the above general formula (4) at both ends. The biphenyl skeleton in the structures represented by the above general formula (3) and the above general formula (4) may be the biphenyl skeleton in the general formula (1).

The phenoxy resin (A) of this embodiment can be represented, for example, by the following general formula (1a).

In the general formula (1a), R ¹ to R ⁴ , X ¹ and X ² have the same meanings as in the general formula (1-2), and m and Q ¹ to Q ⁴ have the same meanings as in the general formula (1-1). When there are a plurality of R ¹ to R ⁴ , Q ¹ to Q ⁴ , X ¹ and X ² , they may be the same or different.
n is a number from 1 to 50 on average, and preferably from 2 to 30.

The repeating units present in plurality can include at least one selected from the repeating unit a and the repeating unit b described above, and may partially include a repeating unit c in which ^X1 and ^X2 are both hydrogen atoms.
X ³ and X ⁴ each represent a glycidyl ether group or a group represented by the following general formula (5).

In formula (5), Z and R ⁵ to R ⁷ have the same meanings as in formula (2). * represents a bond.

The weight average molecular weight (Mw) of the phenoxy resin (A) is 2,000 or more and 30,000 or less, preferably 2,000 or more and 20,000 or less, and more preferably 2,000 to 10,000. Mw is measured by gel permeation chromatography and is expressed as a value converted using a standard polystyrene calibration curve.
By setting the Mw within the above range, the thermal conductivity and flowability of the phenoxy resin can be further improved.
In this embodiment, a molecular weight distribution curve for the phenoxy resin is obtained using GPC (Gel Permeation Chromatography).

The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (PDI: Mw/Mn) of the phenoxy resin (A) are calculated using polystyrene-equivalent values obtained from a calibration curve of standard polystyrene (PS) obtained by GPC measurement.
The measurement conditions for GPC are, for example, as follows.
Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/ml

The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity index (PDI: Mw/Mn) of the phenoxy resin (A) are calculated using polystyrene-equivalent values obtained from a calibration curve of standard polystyrene (PS) obtained by GPC measurement.
The dispersity (Mw/Mn) of the phenoxy resin (A) is, for example, 1.00 to 5.00, preferably 1.20 to 4.00, and more preferably 1.30 to 3.50. By setting the dispersity within the above range, the thermal conductivity and fluidity of the phenoxy resin (A) can be further improved.

From the viewpoint of the effects of the present invention, the epoxy equivalent of the phenoxy resin (A) is 300 g/eq or more and 6,000 g/eq or less, preferably 350 g/eq or more and 5,000 g/eq or less, and more preferably 400 g/eq or more and 4,500 g/eq or less.

The melt viscosity of the phenoxy resin (A) at 180°C is 50 mPa·s or less, preferably 30 mPa·s or less. This provides excellent moldability and excellent manufacturing stability for sealing materials, resin sheets, and resin films.

[Method for producing phenoxy resin (A)]
The method for producing the phenoxy resin (A) having a repeating unit represented by general formula (1) of this embodiment includes the following step (a) and step (b) shown in the following reaction formula.

Step (a): A bifunctional epoxy compound (a) represented by general formula (a) is reacted with a bifunctional phenol compound (b) represented by general formula (b) to synthesize a phenoxy resin (c) containing a repeating unit represented by general formula (c).

Step (b): The obtained phenoxy resin (c) is melt-mixed and reacted with an isocyanate compound (d) represented by general formula (d) to synthesize a phenoxy resin (A) (modified phenoxy resin (A)) having a repeating unit represented by general formula (1).

In formulae (a) and (c), R ¹ to R ⁴ have the same meanings as in formula (1-2), and in formulae (b) and (c), Q ¹ to Q ⁴ and m have the same meanings as in formula (1-1).
The above reaction can be carried out in the absence of a solvent or in the presence of a reaction solvent using a reaction catalyst.

[Step (a)]
Specifically, this step involves adding a bifunctional epoxy compound (a) represented by general formula (a), a bifunctional phenol compound (b) represented by general formula (b), a reaction catalyst, and, if necessary, a reaction solvent, and melt-mixing them under stirring to synthesize a phenoxy resin (c) having a repeating unit represented by general formula (c). The heating temperature during melt-mixing is about 90 to 150°C, the mixing time is about 30 minutes to 5 hours, and the reaction pressure is normal pressure.

As the reaction solvent, aprotic organic solvents such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, sulfolane, propylene glycol monomethyl ether, and cyclohexanone can be suitably used.
By using a reaction solvent, the initial viscosity can be reduced and the reactivity of the monomers is improved.

As the reaction catalyst, a conventionally known polymerization catalyst can be used, and alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, and imidazole compounds are preferably used.

After melt mixing, the mixed solution is heated and the polymerization reaction is carried out at a specified reaction temperature under reduced or normal pressure. The reaction temperature is about 140 to 180°C, the reaction time is about 2 to 10 hours, and the reaction pressure is about 1 to 760 Torr.

The phenoxy resin (c) having a repeating unit represented by general formula (c) can have, for example, a structure represented by the following general formula (4) at its terminal. The biphenyl skeleton in the structure represented by the following general formula (4) may be a biphenyl skeleton in the repeating unit of general formula (c).

In formula (4), R ¹ to R ⁴ have the same meaning as in formula (1-2). * indicates a bond.

[Step (b)]
Specifically, in this step, an isocyanate compound (d) represented by general formula (d) is added to a reaction solution containing a phenoxy resin (c), and these are melt-mixed and reacted to synthesize a phenoxy resin (A) having a repeating unit represented by general formula (1).
The mixing time is about 1 to 10 hours. The heating temperature and reaction pressure are the same as those in step (a).

In this step (b), the isocyanate compound (d) can react with a hydroxyl group of the phenoxy resin (c) to generate a group containing a group represented by the following general formula (2) at X ¹ and X ² of the general formula (1), and can react with a glycidyl ether group of the phenoxy resin (c) to generate a group represented by the following general formula (5) at the terminals X ³ and X ⁴ of the general formula (1).

In formula (2), Z and R ⁵ to R ⁷ are as defined above. * indicates a bond.

In formula (5), Z and R ⁵ to R ⁷ have the same meanings as in formula (2). * represents a bond.
Specifically, the phenoxy resin (A) of the present embodiment has, in its structure,
A repeating unit a in which ^X1 and ^X2 are both a group represented by general formula (2), and a repeating unit b in which ^X1 and ^X2 are a combination of a group represented by general formula (2) and a hydrogen atom;
It is possible to include at least one selected from the following.
The phenoxy resin (A) of the present embodiment may contain a repeating unit c in which X ¹ and X ² are both hydrogen atoms.

In the phenoxy resin (A) of this embodiment, ^X3 and ^X4 each represent a glycidyl ether group or a group represented by general formula (5), and at least a part of them is a group represented by general formula (5).

After the reaction is completed, the phenoxy resin (A) can be obtained by replacing the solvent in a suitable solvent. The phenoxy resin (A) obtained by the solvent reaction can be obtained as a solvent-free solid resin by removing the solvent using an evaporator or the like.
The phenoxy resin (A) of the general formula (1) of this embodiment can be obtained by the above synthesis method.

The phenoxy resin (A) of this embodiment can be obtained as a mixture containing impurities such as ionic impurities and low molecular weight components. When the phenoxy resin contains these components, it can also be called a phenoxy resin composition.

The phenoxy resin (A) can be obtained by purifying the crude phenoxy resin (phenoxy resin composition) containing impurities obtained after synthesis. By setting the allowable values of impurities as described below, it is possible to obtain a desired phenoxy resin composition and reduce the purification load. Furthermore, by containing a predetermined amount of impurities, a predetermined effect can be obtained.
In this specification, the phenoxy resin can be defined as containing impurities such as ionic impurities and low molecular weight components, but not containing solvent.

From the viewpoint of insulating properties, the phenoxy resin (A) of this embodiment may contain ionic impurities in an amount of 1,500 ppm or less, preferably 1,300 ppm or less, and more preferably 1,200 ppm or less.

Examples of the ionic _impurities include F-, ^Cl- , _NO2- ^{, Br-} _{, NO3-} ^{, PO43-} , _SO42- , (COO) ^{22- ,} _CH3COO- ^, and ^HCOO- .

The ionic impurity concentration can be measured, for example, as follows. First, the phenoxy resin is weighed into a container, and ultrapure water is added and the container is sealed. Next, hot water extraction is performed by heat treatment at a temperature of 125° C. for 20 hours using a thermostatic bath. Next, the phenoxy resin (A) and the like are removed from the solution obtained by hot water extraction by centrifugation, filtration, etc. to prepare a test liquid. Next, the ionic impurity content in the test liquid is measured by a calibration curve method using a standard solution using an ion chromatography analyzer. The ionic impurity content relative to the phenoxy resin (A) used to prepare the test liquid was taken as the ionic impurity concentration.
The ionic impurities may include hydrolyzable chlorine.
From the viewpoint of insulating properties, the phenoxy resin of the present embodiment may contain ionic impurities including hydrolyzable chlorine in the above-mentioned amount.
The hydrolyzable chlorine concentration can be measured, for example, as follows.

First, phenoxy resin, acetone-methanol mixed solution, and CH ₃ ONa methanol solution are mixed, and BTB solution is added as an indicator. Next, nitric acid is added until the solution turns yellow, and the above indicator is further added. Potentiometric titration is performed on this solution using an automatic titrator (using a silver electrode) with an aqueous silver nitrate solution to determine the amount of hydrolyzable chlorine. The amount of hydrolyzable chlorine relative to the phenoxy resin (A) is taken as the hydrolyzable chlorine concentration.
The low molecular weight component contained in the phenoxy resin of the present embodiment is a component having a weight average molecular weight Mw of 1,000 or less.

The low molecular weight component may contain at least one of the monomer components (C) (bifunctional epoxy compound (a), bifunctional phenol compound (b)) contained in the phenoxy resin, and a low molecular weight component (B) having an Mw of 1k or less and not including the monomer component (C). The low molecular weight component (B) may be composed of one or more polymers of the monomer components (C).

By reducing the amount of low molecular weight components contained in the phenoxy resin, the thermal conductivity can be increased and the fluidity of the phenoxy resin can be improved.

The peak area corresponding to the low molecular weight components (B+C) in the phenoxy resin with Mw of 1k or less is calculated from the ratio of the total area of components with a weight average molecular weight Mw of 1,000 or less to the total area of the entire molecular weight distribution (100%), based on data on molecular weight obtained, for example, by GPC measurement.

This low molecular weight component (B+C) with Mw of 1k or less includes monomer component (C) and low molecular weight component (B) with Mw of 1,000 or less that does not contain monomer component (C).

The total peak area of 100% is defined as the sum of the peak areas of the phenoxy resin (A), the monomer component (C), and the low molecular weight component (B) having an Mw of 1,000 or less and not including the monomer component (C).

The peak area of the above low molecular weight components (B+C) can be set to 10% or less, preferably 7% or less. This can further improve the thermal conductivity of the phenoxy resin.

In addition, in the molecular weight distribution of the phenoxy resin obtained by GPC measurement, the peak area of the low molecular weight component (B) with Mw of 1,000 or less can be 7% or less, preferably 5% or less, relative to the total peak area of 100%. This can further improve the thermal conductivity of the phenoxy resin.

The low molecular weight component (B) with Mw of 1,000 or less does not contain monomer component (C). The peak area ratio of this low molecular weight component (B) with Mw of 1,000 or less represents the content ratio of low-molecular weight components (low molecular weight polymer components) contained in the low molecular weight component.

In the molecular weight distribution of the phenoxy resin obtained by GPC measurement, the peak area of the monomer component (C) relative to the total peak area of 100% can be 3% or less, preferably 2% or less, thereby further improving the thermal conductivity of the phenoxy resin.
Furthermore, the melting point and melt viscosity of the phenoxy resin can be adjusted by the molecular weight of the phenoxy resin (A) and the amount of the low molecular weight component.

In this embodiment, for example, by appropriately selecting the type and amount of each component contained in the phenoxy resin (A), the preparation method of the phenoxy resin, etc., it is possible to control the peak area of the low molecular weight components (B + C) in the phenoxy resin, the peak area of the low molecular weight component (B), and the Mw and Mw/Mn of the phenoxy resin (A). Among these, for example, appropriately selecting the synthesis conditions of the phenoxy resin (A), such as the reaction temperature, reaction time, and removal of monomers, is cited as an element for setting the peak area of the low molecular weight components (B + C) in the phenoxy resin, the peak area of the low molecular weight component (B), and the Mw and Mw/Mn of the phenoxy resin (A) in the desired numerical range.

[Method of producing resin-coated inorganic particles]
The method for producing resin-coated inorganic particles according to the present embodiment includes the steps of: dispersing inorganic particles (a) in an organic solvent;
mixing the obtained dispersion with a resin (b) containing a resin (b1) having two or more mesogenic skeletons in the molecule;
a step of distilling off the organic solvent from the obtained mixed liquid, and then heating the mixture to coat the surfaces of the inorganic particles (a) with the resin (b);
including.
The conditions for each step are appropriately selected depending on the types and amounts of the organic solvent, inorganic particles (a), and resin (b).

The amount of resin (b) added per 100 parts by weight of inorganic particles (a) is not particularly limited, but is preferably 0.01 parts by weight or more and 2 parts by weight or less, more preferably 0.02 parts by weight or more and 1 part by weight or less, and particularly preferably 0.03 parts by weight or more and 0.8 parts by weight or less.
Examples of the organic solvent include ethanol, methanol, isopropyl alcohol, acetone, cyclohexanone, dimethylformamide, and tetrahydrofuran.

In addition to the method for preparing the resin-coated inorganic particles as described above, the coated inorganic particles can also be prepared simultaneously when preparing the thermosetting resin composition described below. The manufacturing method will be described later.

[Thermosetting resin composition]
The thermosetting resin composition of the present embodiment contains the above-mentioned resin-coated inorganic particles, an epoxy resin, and a thermosetting resin (excluding the epoxy resin).

The thermosetting resin composition containing the resin-coated inorganic particles of this embodiment can provide a cured resin with excellent thermal conductivity. Furthermore, the thermosetting resin composition of this embodiment has excellent flowability and therefore excellent moldability, and when used as an encapsulating resin, wire sweep and the like are suppressed, improving the yield of semiconductor devices. Furthermore, the thermosetting resin composition of this embodiment has a relatively short curing time and improved productivity. In other words, the thermosetting resin composition of the present invention has an excellent balance of these properties.
The thermosetting resin composition may contain a thermosetting resin other than an epoxy resin.

Examples of the thermosetting resin include polyimide resin, benzoxazine resin, unsaturated polyester resin, phenol resin, melamine resin, silicone resin, cyanate resin, bismaleimide resin, acrylic resin, phenol derivatives, and derivatives thereof. As the thermosetting resin, a monomer, oligomer, or polymer having two or more reactive functional groups in one molecule can be used, and the molecular weight or molecular structure is not particularly limited. These may be used alone or in combination of two or more.
The thermosetting resin composition may contain a curing agent, if necessary.
The curing agent is selected depending on the type of thermosetting resin, and is not particularly limited as long as it reacts with the thermosetting resin.

Examples of the curing agent include phenolic resin curing agents, amine curing agents, acid anhydride curing agents, mercaptan curing agents, etc. These may be used alone or in combination of two or more kinds.
The thermosetting resin composition may contain a curing accelerator as 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 properties, and the like.

Examples of the curing accelerator include imidazoles, organic phosphorus compounds, tertiary amines, phenolic compounds, organic acids, etc. These may be used alone or in combination of two or more. Among these, from the viewpoint of improving heat resistance, it is preferable to use nitrogen atom-containing compounds such as imidazoles.
The thermosetting resin composition may contain a silane coupling agent.

This can further improve the compatibility of the resin-coated inorganic particles in the thermosetting resin composition. The coupling agent may be added to the thermosetting resin composition, or may be used by treating the surface of the resin-coated inorganic particles.

The thermosetting resin composition of this embodiment may contain other components in addition to the above-mentioned components. Examples of the other components include a curing retarder, a release agent, a colorant, a stress reducing agent, an antioxidant, and a leveling agent.

The thermosetting resin composition containing the resin-coated inorganic particles of this embodiment has excellent thermal conductivity and can be used in a variety of applications. For example, a semiconductor device encapsulated with a cured product made of the thermosetting resin composition and a thermally conductive resin sheet using the cured product can be mentioned.

[Semiconductor device]
The semiconductor device of the present embodiment is one in which a semiconductor element and the like are encapsulated with a cured product of a thermosetting resin composition containing resin-coated inorganic particles. The resin-coated inorganic particles have excellent compatibility with resin components and excellent thermal conductivity, and therefore can effectively dissipate heat from the semiconductor element, substrate, etc.

When the thermosetting resin composition of this embodiment is used as an encapsulating resin composition, the manufacturing method thereof includes a step of mixing resin-coated inorganic particles, an epoxy resin, a curing agent, a thermosetting resin (excluding the epoxy resin), and, if necessary, inorganic particles, a low-stress agent, etc., a step of melt-kneading the mixture in a kneader, and a step of cooling and then pulverizing the mixture.

There are no particular limitations on the mixing method, but the mixture of materials such as resin, hardener, and filler can be prepared by mixing them without melting them using a device such as a Henschel mixer or planetary mixer.

The process of melt-kneading in a kneader involves melt-kneading the aforementioned resin, inorganic particles, and low-stress agent using a roll, kneader, extruder, or the like. The melt-kneading conditions can be known conditions.

In this embodiment, the coated inorganic particles can be prepared simultaneously when the thermosetting resin composition is prepared by a production method having the following steps.
Step (1): A resin (b) containing a resin (b1) having two or more mesogenic skeletons in the molecule is dispersed in an organic solvent to obtain a dispersion liquid.
Step (2): The inorganic particles (a), an epoxy resin, a thermosetting resin (excluding the epoxy resin), and the dispersion liquid are mixed to obtain a mixture.
Step (3): The mixture is heated and kneaded.

(Step (1))
Examples of the organic solvent used in this step include ethanol, methanol, isopropyl alcohol, acetone, cyclohexanone, dimethylformamide, tetrahydrofuran, etc. Specifically, the resin (b) can be dispersed in the organic solvent by a known stirring means at room temperature and normal pressure, the amount of the resin (b) added to the organic solvent is not particularly limited, and the stirring time is also appropriately selected depending on the combination of the organic solvent and the resin (b).
A known dispersant, adhesive, or the like may also be added to the organic solvent.

(Step (2))
In this step, the inorganic particles (a), the epoxy resin, the thermosetting resin (excluding the epoxy resin), and the dispersion obtained in the step (1) are mixed to obtain a mixture.
The mixing method is not particularly limited, but specific examples of the method for mixing with the dispersion obtained in step (1) include a method of dropping the dispersion into the melt-kneaded components, and a method of adding the dispersion all at once.

(Step (3))
The mixture is heated and kneaded in a kneader. Specifically, each component is melt-kneaded by a roll, a kneader, an extruder, etc. The melt-kneading conditions can be known conditions.

By using the above method, inorganic particles can be coated with resin (b) to obtain coated inorganic particles, and a thermosetting resin composition containing the coated inorganic particles can be prepared.

Whether or not resin-coated inorganic particles were obtained was determined as follows.
The resin-coated inorganic particles were taken out from the composite powder (thermosetting resin composition), washed with a good solvent to remove the phenoxy resin firmly attached to the surface, and the surface was similarly measured with the FT-IR device.
As a result, a peak at >3000 cm-1 derived from the C=C bond of the aromatic ring can be detected, confirming that the inorganic particle surface is coated with the phenoxy resin.

The thermosetting resin composition can be cooled and then pulverized to obtain a granular or tablet-like thermosetting resin composition (encapsulating resin composition). The obtained granular or tablet-like thermosetting resin composition can be encapsulated using known molding methods such as transfer molding, injection molding, and compression molding.

The thermosetting resin composition of this embodiment can be used for various applications, such as a resin composition for sealing semiconductor elements such as general semiconductor elements and power semiconductors, a resin composition for sealing wafers, a resin composition for forming pseudo wafers, a resin composition for sealing electronic control units for vehicles, a resin composition for sealing wiring boards, and a resin composition for sealing rotor fixing members.

The thermosetting resin composition according to this embodiment can be used in a semiconductor device as a sealing member that seals a semiconductor element mounted on a substrate. That is, the semiconductor device according to this embodiment is a semiconductor device that includes a semiconductor element mounted on a substrate and a sealing member that seals the semiconductor element, and the sealing member is composed of a cured product of the above-mentioned sealing resin composition.

The method for forming the sealing member is not limited, but examples include transfer molding, compression molding, and injection molding. By using these methods, the thermosetting resin composition can be molded and cured to form the sealing member.

The semiconductor element is not limited, and a known semiconductor element can be selected depending on the application of the semiconductor device. Specific examples of the semiconductor element include integrated circuits, large-scale integrated circuits, transistors, thyristors, diodes, and solid-state imaging elements.

The substrate is not limited, and a known semiconductor device can be selected depending on the application of the semiconductor device. Specific examples of the substrate include wiring boards such as interposers and lead frames.

If electrical connection between the semiconductor element and the substrate is required, they may be connected as appropriate. There are no limitations on the method of electrical connection, but specific examples include wire bonding and flip chip connection.

In this embodiment, a useful electrical connection method is wire bonding among the above specific examples. That is, in the semiconductor device according to this embodiment, the semiconductor element is connected to the substrate via a bonding wire, and when the bonding wire is sealed with a sealing member, the thermosetting resin composition of this embodiment has excellent fluidity, so that wire sweep and the like are suppressed, and the yield of the semiconductor device is improved.

Specific types of semiconductor devices according to this embodiment include MAP (Mold Array Package), QFP (Quad Flat Package), SOP (Small Outline Package), QFN (Quad Flat Non-leaded Package), SON (Small Outline Non-leaded Package), BGA (Ball Grid Array), LF-BGA (Lead Frame BGA), FCBGA (Flip Chip BGA), MAPBGA (Molded Array Process BGA), eWLB (Embedded Examples include wafer-level BGA), fan-in type eWLB, and fan-out type eWLB.

A semiconductor device using the thermosetting resin composition according to this embodiment will be described below with reference to FIGS. 1 and 2. FIG.
1 is a cross-sectional view showing an example of a semiconductor device 100 according to this embodiment. Here, a base material 30 is, for example, a lead frame.

The semiconductor device 100 of this embodiment includes a semiconductor element 20, a bonding wire 40 connected to the semiconductor element 20, and a sealing member 50, and the sealing member 50 is made of a cured product of the above-mentioned thermosetting resin composition.

More specifically, the semiconductor element 20 is fixed onto a substrate 30 via a die attach material 10, and the semiconductor device 100 has outer leads 34 connected via bonding wires 40 from electrode pads 22 provided on the semiconductor element 20. The bonding wires 40 can be set according to the semiconductor element 20 used, and may be, for example, Cu wires.
The semiconductor element 20 may be fixed onto a die pad 32 provided on the substrate 30 via the die attachment material 10 .
FIG. 2 is a cross-sectional view showing a modification of the semiconductor device 100 shown in FIG.

Here, the substrate 30 is, for example, an interposer. In the substrate 30, for example, a plurality of solder balls 52 are formed on the surface opposite to the surface on which the semiconductor element 20 is fixed.

(Thermal conductive resin sheet)
The thermally conductive resin sheet of the present embodiment includes a carrier substrate and a resin layer formed on the carrier substrate and made of the thermosetting resin composition of the present embodiment. The phenoxy resin (A) of the present embodiment is firmly attached to the surface of the carrier substrate, and has excellent compatibility with the resin component and excellent thermal conductivity, so that the heat of the carrier substrate and the like can be suitably dissipated.
When the thermosetting resin composition of the present embodiment is used as a resin layer of a thermally conductive resin sheet, the thermosetting resin composition can be produced, for example, by the following method.

The resin varnish (thermosetting resin composition in varnish form) can be prepared by dissolving, mixing, and stirring the above-mentioned phenoxy resin (A), epoxy resin, thermosetting resin (excluding the above-mentioned phenoxy resin and the above-mentioned epoxy resin), inorganic particles, and, if necessary, a low stress agent, etc., in a solvent. This mixing can be performed using various mixers such as ultrasonic dispersion type, high-pressure collision type dispersion type, high-speed rotation dispersion type, bead mill type, high-speed shear dispersion type, and rotation-revolution type dispersion type.

The above solvents are not particularly limited, but include acetone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone.

The resin sheet can be obtained, for example, by applying a varnish-like thermosetting resin composition onto a carrier substrate to obtain a coating film (resin layer) and then carrying out a solvent removal process. 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 process can be carried out under conditions of 80°C to 200°C and 1 minute to 30 minutes.

In this embodiment, the carrier substrate may be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, release papers such as silicone sheets, and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and/or copper-based alloys, aluminum and/or aluminum-based alloys, iron and/or iron-based alloys, silver and/or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys.

(Resin substrate)
The resin substrate of the present embodiment includes an insulating layer made of the cured product of the thermosetting resin composition. This resin substrate can be used as a material for a printed circuit board on which electronic components such as LEDs and power modules are mounted.

(Metal base substrate)
As an example of this embodiment, a metal base substrate 60 will be described with reference to FIG.
FIG. 3 is a cross-sectional view showing an example of the configuration of the metal base substrate 60. As shown in FIG.

As shown in FIG. 3, the metal base substrate 60 can include a metal substrate 70, an insulating layer 80 provided on the metal substrate 70, and a metal layer 90 provided on the insulating layer 80. The insulating layer 80 can be made of one selected from the group consisting of a resin layer made of the above-mentioned thermosetting resin composition, a cured product of the thermosetting resin composition, and a laminate. Each of these resin layers and laminates may be made of a thermosetting resin composition in a B-stage state before the circuit processing of the metal layer 90, and may be a cured product obtained by curing the resin composition after the circuit processing.

The metal layer 90 is provided on the insulating layer 80 and is processed into a circuit. Examples of metals constituting the metal layer 90 include one or more selected from copper, copper alloys, aluminum, aluminum alloys, nickel, iron, tin, and the like. Among these, the metal layer 90 is preferably a copper layer or an aluminum layer, and is particularly preferably a copper layer. By using copper or aluminum, the circuit processability of the metal layer 90 can be improved. The metal layer 90 may be a metal foil available in a plate shape or a metal foil available in a roll shape.
The lower limit of the thickness of the metal layer 90 is, for example, 0.01 mm or more, and preferably 0.035 mm or more, so long as it is applicable to applications requiring a high current.

The upper limit of the thickness of the metal layer 90 is, for example, 10.0 mm or less, and preferably 5 mm or less. If it is below this value, the circuit processing can be improved, and the board as a whole can be made thinner.

The metal substrate 70 has a role of dissipating heat accumulated in the metal base substrate 60. The metal substrate 70 is not particularly limited as long as it is a heat dissipating metal substrate, but may be, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate, with a copper substrate or an aluminum substrate being preferred, and a copper substrate being more preferred. By using a copper substrate or an aluminum substrate, the heat dissipation properties of the metal substrate 70 can be improved.
The thickness of the metal substrate 70 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 70 is, for example, 20.0 mm or less, and preferably 5.0 mm or less. By using a metal substrate 70 with a thickness of less than this value, the workability of the metal base substrate 60 can be improved in the external processing and cutting processing, etc.

The lower limit of the thickness of the metal substrate 70 is, for example, 0.01 mm or more, and preferably 0.6 mm or more. By using a metal substrate 70 with a thickness of this value or more, the heat dissipation properties of the metal base substrate 60 as a whole can be improved.

In this embodiment, the metal base substrate 60 can be used for various substrate applications, but because it has excellent thermal conductivity and heat resistance, it can be used as a printed circuit board that uses LEDs and power modules.

The metal base substrate 60 may have a metal layer 90 that has been circuitized by etching or the like into a pattern. In this metal base substrate 60, a solder resist (not shown) may be formed on the outermost layer, and connection electrodes may be exposed so that electronic components can be mounted by exposure and development.

The above describes embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can be adopted as long as they do not impair the effects of the present invention.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
The raw materials used in the synthesis examples are as follows:

(Epoxy Compound)
YX4000: Tetramethylbiphenyl type epoxy resin represented by the following chemical formula (bifunctional epoxy compound, having a mesogen structure, manufactured by Mitsubishi Chemical Corporation, YX4000)

- 4,4'-biphenyl diglycidyl ether (has a mesogenic structure, synthesized by Sumitomo Bakelite Co., Ltd.) represented by the following chemical formula

(Phenol compounds)
HQHBA: ester group-containing bisphenol represented by the following chemical formula (HQHBA, bifunctional phenol compound, has a mesogen structure, manufactured by Ueno Pharmaceutical Co., Ltd.)

- Hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.) represented by the following chemical formula

(Synthesis Example 1)
<Synthesis of phenoxy resin (c-1)>
69.2 parts by weight of an epoxy compound (YX4000), 24.9 parts by weight of a phenol compound (HQHBA), and 0.1 parts by weight of triphenylphosphine (TPP) were added to a reactor and reacted by melt mixing at 150° C. for 1 hour. It was confirmed by GPC that the desired molecular weight was achieved, and that a phenoxy resin (c-1) represented by the following chemical formula (average number of repeating units n is 4.4) was obtained.

The measurement conditions for GPC are as follows.
- Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/milliliter

<Synthesis of Modified Phenoxy Resin (A-1)>
To the molten mixture containing the phenoxy resin (c-1), 5.8 parts by weight of 3-isocyanatopropyltriethoxysilane was added, and the reaction was continued for another 7 hours. After the reaction, the resulting molten resin was cooled to room temperature. After cooling, it was pulverized to obtain 100 parts by weight of a brown solid modified phenoxy resin (A) represented by the following chemical formula (the average value of the number of repeating units n in the chemical formula is 8.3).
The resulting modified phenoxy resin (A-1) had a molecular weight of 4,500 mol/g in terms of the refractive index of polystyrene, and an epoxy equivalent of 534 g/eq.

In the above chemical formula, ^X1 and ^X2 represent a hydrogen atom or the following groups, at least some of which are the following groups:

In the above chemical formula, ^X3 and ^X4 represent a glycidyl ether group or the following group, at least a portion of which is the following group:

The results of ¹ H-NMR are shown below. It was confirmed from ¹ H-NMR that the amount of the Si component mixed in was about 6 mol % based on the molar amount of the epoxy group of the epoxy compound (YX4000), which was consistent with the charged weight.

δ [ppm] (400 MHz, DMSO-d6):
8.1 (1H, d, 8.8 Hz, Ar-H), 7.2 (7H, m, Ar-H), 5.4 (1H, m, _CH2- CH(OH) _-CH2 ), 4.2-3.5 (7H, m, O- _CH2 -CH, O-CH2-CH, Si- _OCH2 , OCH2CHCH2), 2.8 (1H, m, _OCH2CH ) _, 2.7 (1H, m, _OCH2CH ), 2.3 (12H, s, _CH3 ), 1.7 (0.1H, _{m ,} SiCH2CH2CH2) _, 1.4 (0.1, m, SiCH2CH2), 1.1 (0.6H, _{m , SiOCH2CH3} ) _, 0.5 (0.1H, m, _SiCH2 ) _.

As a result of FT-IR measurement, broad peaks derived from OH groups and NH groups were confirmed near 3500 cm ^-1 . Furthermore, a peak derived from the isocyanate group of the raw material (3-isocyanatopropyltriethoxysilane) (near 2200 cm ^-1 ) was not detected. Peaks derived from ester groups, oxazolidone rings, and urethane bonds were confirmed near 1720 cm ^-1 . Peaks derived from ester groups were confirmed near 1100 to 1210 cm ^-1 . Peaks derived from alkoxysilanes were confirmed near 1105 and 950 ^{cm -1} .

(Synthesis Example 2)
<Synthesis of phenoxy resin (c-2)>
81.1 parts by weight of an epoxy compound (4,4'-biphenyl diglycidyl ether), 14.5 parts by weight of a phenol compound (hydroquinone), and 0.1 parts by weight of triphenylphosphine (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a reactor and reacted by melt mixing at 150°C for 1 hour. It was confirmed by GPC that the desired molecular weight was achieved, and that a phenoxy resin (c-2) represented by the following chemical formula (average value of the number of repeating units n is 3.8) was obtained.

<Synthesis of Modified Phenoxy Resin (A-2)>
To the molten mixture containing the phenoxy resin (c-2), 4.3 parts by weight of 3-isocyanatopropyltriethoxysilane was added, and the reaction was continued for another 7 hours. After the reaction, the resulting molten resin was cooled to room temperature. After cooling, it was pulverized to obtain 100 parts by weight of a white solid modified phenoxy resin (A-2) represented by the following chemical formula (the average value of the number of repeating units n in the chemical formula is 13.2).
The resulting modified phenoxy resin (A-2) had a molecular weight of 5,600 mol/g in terms of the refractive index of polystyrene, and an epoxy equivalent of 562 g/eq.

In the above chemical formula, ^X1 and ^X2 represent a hydrogen atom or the following groups, at least some of which are the following groups:

In the above chemical formula, ^X3 and ^X4 represent a glycidyl ether group or the following group, at least a portion of which is the following group:

The results of ¹ H-NMR are shown below. It was confirmed from ¹ H-NMR that the amount of the Si component mixed in was about 6 mol % based on the molar amount of the epoxy group of the epoxy compound (4,4'-biphenyl diglycidyl ether), which was consistent with the charged weight.

δ [ppm] (400 MHz, DMSO-d6):
7.5 (8H, m, Ar-H), 7.0 (8H, m, Ar-H), 6.9 (4H, m, Ar-H), 5.4 (3H, m, _CH2 -CH(OH) _-CH2 ), 5.4-3.7 (27H, m, _CH2 -CH-O- _CH2 , CH2 _- CH-O, Si- _OCH2 ), 2.8-2.6 (4H, m _{, CH2OCHCH2} ), 1.7 (0.1H, m _{, CH2CH2CH2Si} ), _1.4 (0.1H, m _{, CH2CH2Si} ), 1.1 (0.6H, m, _SiOCH2CH3 ), 0.5 (0.1H, m, _SiCH2 ) _.

As a result of FT-IR measurement, broad peaks derived from OH groups and NH groups were confirmed near 3500 cm ^-1 . Furthermore, a peak derived from the isocyanate group of the raw material (3-isocyanatopropyltriethoxysilane) (near 2200 cm ^-1 ) was not detected. Peaks derived from oxazolidone rings and urethane bonds were confirmed at 1701 cm ^-1 . Peaks derived from alkoxysilanes were confirmed near 1105 and 950 cm ^-1 .

(Synthesis Example 3)
<Synthesis of phenoxy resin (c-3)>
73.4 parts by weight of an epoxy compound (YX4000), 26.5 parts by weight of a phenol compound (HQHBA), and 0.1 parts by weight of triphenylphosphine (TPP) were dropped into a reactor and melt-mixed and reacted at 150°C for 7 hours. After the reaction, the resulting molten resin was cooled to room temperature. After cooling, the mixture was pulverized to obtain a brown solid. It was confirmed by GPC that the desired molecular weight was obtained, and that a phenoxy resin (c-3) represented by the following chemical formula (the average value of the number of repeating units n is 7.8) was obtained. The molecular weight of the phenoxy resin (c-3) was 4200 mol/g in terms of the polystyrene refractive index, and the epoxy equivalent was 515 g/eq.

The phenoxy resin obtained in the above synthesis example was used to treat a filler, and the treated filler was used to prepare a thermosetting resin composition.
Epoxy resin: biphenyl type epoxy resin (YX-4000K, manufactured by Mitsubishi Chemical Corporation)
Phenol hardener 1: Novolac type phenolic resin having the following structure, weight average molecular weight 500 (polystyrene equivalent)

Phenol hardener 2: 4,4'-biphenol Filler 1 (untreated): Alumina filler (DAB-30FC, manufactured by Denka Co., Ltd., average particle size 13 μm)
Amine coupling agent: CF-4083 (N-phenyl-γ-aminopropyltrimethoxysilane, manufactured by Dow Corning Toray Co., Ltd.)
Curing catalyst: PP-360 (triphenylphosphine, manufactured by K.I. Chemicals Co., Ltd.)
Hardening retarder: 2,3-dihydroxynaphthalene (manufactured by Air Water Inc.)
Release agent: Synthetic wax (WE-4, Clariant Chemicals Co., Ltd.)
Colorant: Carbon black (Carbon #5, manufactured by Mitsubishi Chemical Corporation)
Low stress agent: Silicone (FZ-3730, manufactured by Dow Corning Toray Co., Ltd.)
Silica fine powder: DAW-02, manufactured by Denka Co., Ltd., average particle size 2.7 μm

Example 1 Preparation of Treated Filler A and Thermosetting Resin Composition
<Preparation of Treated Filler A>
68.9 parts by weight of Filler 1 (alumina filler), 31 parts by weight of ethanol, and 0.05 parts by weight of the modified phenoxy resin (A-1) obtained in Synthesis Example 1 were weighed out and dispersed by stirring for 12 hours. After stirring, the solvent was distilled off, and the mixture was dried by heating at 120°C for 3 hours to obtain Treated Filler A.

<Preparation of Thermosetting Resin Composition>
The raw materials shown in Table 1 were weighed out by predetermined weight, melt-kneaded at 80°C for 20 minutes, and then cooled to room temperature. The solid matter obtained was pulverized to prepare a composite powder (thermosetting resin composition). The physical properties of the obtained composite powder were measured by the following method. The results are shown in Table 1.

Measurement of Spiral Flow (Fluidity) A spiral flow test was carried out using the composite powders of the examples and comparative examples.
The test was performed by using a low pressure transfer molding machine ("KTS-15" manufactured by Kotaki Seiki Co., Ltd.) to inject the composite powder into a metal mold for spiral flow measurement conforming to EMMI-1-66 under the conditions of a metal mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 120 seconds, and measuring the flow length. A larger value indicates better flowability.

Measurement of gel time: The powdered composite powder was placed on a hot plate set at 175°C. After the composite powder melted, the time until it hardened (the time until it could no longer be kneaded with a spatula) was measured while kneading it with a spatula. A relatively short hardening time means that the moldability is excellent. The results are shown in Table 1.

Measurement of thermal conductivity The composite powders of the examples and comparative examples were compression molded at 180°C/2 MPa/15 minutes, and then heat-treated in an oven at 180°C/3 hours to produce cured products. The obtained cured products were processed into a diameter of 10 mm x thickness of 1 mm and used as samples for measuring thermal diffusivity.
The thermal diffusivity (α) in the thickness direction of the plate-shaped thermal diffusivity measurement sample was measured by a non-steady method using a Xe flash analyzer TD-1RTV manufactured by ULVAC, Inc. The measurement was performed under the conditions of air and 25°C.
The thermal conductivity of the sample was calculated from the measured values of thermal diffusion coefficient (α), specific heat (Cp), and specific gravity (SP) according to the following formula. The results are shown in Table 1.
Thermal conductivity [W/m·K] = α [m ² /s] × Cp [J/kg·K] × Sp [g/cm ³ ]

Example 2 Preparation of Treated Filler B and Thermosetting Resin Composition
Treated filler B and a thermosetting resin composition were prepared in the same manner as in Example 1, except that the amount of modified phenoxy resin (A-1) was 0.1 parts by weight, and the physical properties were measured.

Example 3 Preparation of Treated Filler C and Thermosetting Resin Composition
Treated filler C and a thermosetting resin composition were prepared in the same manner as in Example 1, except that the amount of modified phenoxy resin (A-1) was 0.2 parts by weight, and the physical properties were measured.

Example 4 Preparation of Treated Filler D and Thermosetting Resin Composition
Treated filler D and a thermosetting resin composition were prepared in the same manner as in Example 1, except that the amount of modified phenoxy resin (A-1) was 0.25 parts by weight, and the physical properties were measured.

Example 5 Preparation of Treated Filler E and Thermosetting Resin Composition
A treated filler E and a thermosetting resin composition were prepared in the same manner as in Example 1, except that 0.1 parts by weight of the modified phenoxy resin (A-2) obtained in Synthesis Example 2 was used instead of 0.05 parts by weight of the modified phenoxy resin (A-1), and the physical properties were measured.

Example 6 Preparation of Treated Filler F and Thermosetting Resin Composition
Treated filler F and a thermosetting resin composition were prepared and their physical properties were measured in the same manner as in Example 1, except that 0.2 parts by weight of modified phenoxy resin (A-2) was used instead of 0.05 parts by weight of modified phenoxy resin (A-1).

Example 7 Preparation of Filler G and Thermosetting Resin Composition
Filler G and a thermosetting resin composition were prepared in the same manner as in Example 1, except that 0.2 parts by weight of the phenoxy resin (c-3) obtained in Synthesis Example 3 was used instead of the modified phenoxy resin (A-1), and the physical properties were measured.

The thermosetting resin composition containing the resin-coated inorganic particles of the examples showed superior thermal conductivity compared to the comparative examples. Such a thermosetting resin composition containing resin-coated inorganic particles can be used as a resin material, and can also be suitably used as a heat dissipation insulating material such as a sealing material for semiconductor devices, and a heat dissipation insulating substrate or sheet.

The thermosetting resin composition of the examples also had excellent fluidity and a relatively short curing time, improving productivity. In other words, the thermosetting resin composition of the examples had an excellent balance of these properties.

Reference Signs List 100 Semiconductor device 10 Die attach material 20 Semiconductor element 22 Electrode pad 30 Substrate 32 Die pad 34 Outer lead 40 Bonding wire 50 Sealing member 52 Solder ball 60 Metal base substrate 70 Metal substrate 80 Insulating layer 90 Metal layer

Claims (19)

(a) inorganic particles;
(b) a resin that coats the surfaces of the inorganic particles (a);
It consists of:
The resin (b) includes a resin (b1) having two or more mesogenic skeletons in the molecule,
The resin (b1) is a resin-coated inorganic particle containing a phenoxy resin . The resin-coated inorganic particles according to claim 1 , wherein the phenoxy resin contains a structural unit derived from a phenol compound and a structural unit derived from an epoxy compound. 3. The resin-coated inorganic particle according to claim 1 , wherein the mesogenic skeleton of the phenoxy resin contains a biphenyl skeleton and/or a phenylbenzoate skeleton. The resin-coated inorganic particles according to claim 1 , wherein the phenoxy resin contains a phenylene skeleton. 5. The resin-coated inorganic particles according to claim 1 , wherein the phenoxy resin is bonded to the surface of the inorganic particles (a) via a Si--O bond. 6. The resin-coated inorganic particle according to claim 5 , wherein the Si atom of the Si--O bond is bonded to a side chain and/or an end of the phenoxy resin. 7. The resin-coated inorganic particles according to claim 1 , wherein the inorganic particles (a) contain at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide and magnesium oxide. The resin-coated inorganic particles according to any one of claims 1 to 7 , wherein the inorganic particles (a) have an average particle size of 0.1 µm or more and 100 µm or less. 9. The resin-coated inorganic particles according to claim 1 , wherein the inorganic particles (a) have a specific surface area of 0.1 m ² /g or more and 5 m ² /g or less. The resin-coated inorganic particles according to any one of claims 1 to 9 ,
Epoxy resin,
A thermosetting resin (excluding the epoxy resin),
A thermosetting resin composition comprising: The thermosetting resin composition according to claim 10 , which is in the form of granules or tablets. A semiconductor device, comprising a semiconductor element encapsulated with a cured product of the thermosetting resin composition according to claim 10 or 11 . A method for producing the resin-coated inorganic particles according to any one of claims 1 to 9, comprising the steps of:
Dispersing inorganic particles (a) in an organic solvent;
mixing the obtained dispersion with a resin (b) containing a resin (b1) having two or more mesogenic skeletons in the molecule;
a step of distilling off the organic solvent from the obtained mixed liquid, and then heating the mixture to coat the surfaces of the inorganic particles (a) with the resin (b);
A method for producing resin-coated inorganic particles, comprising: The method for producing resin-coated inorganic particles according to claim 13 , wherein the resin (b1) contains a phenoxy resin. The method for producing resin-coated inorganic particles according to claim 13 or 14 , wherein the resin (b1) comprises a SiR _n (OR) _m group (wherein m is an integer of 1 to 3, n+m=3, and R represents an organic group). The method for producing resin-coated inorganic particles according to any one of claims 13 to 15 , wherein the resin (b1) comprises a phenoxy resin containing a repeating unit represented by the following general formula (1):

In general formula (1), R ¹ to R ⁴ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an allyl group.
Q ¹ to Q ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.
m is 0 or 1. * indicates a bond.
^X1 and ^X2 are each a hydrogen atom or a group represented by the following general formula (2), and at least one of ^X1 and ^X2 is a group represented by the following general formula (2).

(In the general formula (2), Z represents an alkylene group having 2 to 10 carbon atoms.
R ⁵ to R ⁷ each independently represent an alkoxy group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms, and at least one of them is an alkoxy group having 1 to 3 carbon atoms. The method for producing resin-coated inorganic particles according to claim 16 , wherein the phenoxy resin has a group represented by the following general formula (3) at an end thereof:

(In formula (3), R ¹ to R ⁴ and R ⁵ to R ⁷ are the same as in formula (1). * represents a bond.) The method for producing resin-coated inorganic particles according to any one of claims 13 to 17 , wherein the inorganic particles (a) contain at least one selected from the group consisting of silica, alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. A method for producing the thermosetting resin composition according to claim 10 or 11, comprising the steps of:
A step of dispersing a resin (b) containing a resin (b1) having two or more mesogenic skeletons in a molecule in an organic solvent to obtain a dispersion;
A step of mixing inorganic particles (a), an epoxy resin, a thermosetting resin (excluding the epoxy resin), and the dispersion liquid to obtain a mixture;
heating and kneading the mixture;
A method for producing a thermosetting resin composition comprising the steps of:

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