JP7358882B2 - Resin composition, resin sheet, B stage sheet, C stage sheet, cured product, metal foil with resin, metal substrate, and power semiconductor device - Google Patents

Description

The present disclosure relates to a resin composition, a resin sheet, a B-stage sheet, a C-stage sheet, a cured product, a resin-coated metal foil, a metal substrate, and a power semiconductor device.

2. Description of the Related Art Electronic component devices use members containing resin (resin members) for purposes such as electrical insulation. BACKGROUND ART In recent years, the amount of heat generated has tended to increase with the miniaturization and higher output of electronic component devices, and how to dissipate the generated heat has become an important issue. However, while resin has excellent insulation properties, it has poor thermal conductivity. Therefore, development of technology for imparting excellent thermal conductivity to resin members is underway (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2014-240466

In the invention described in Patent Document 1, improvement in thermal conductivity is achieved by using a thermally conductive resin sheet containing a thermally conductive filler and a resin composition containing an epoxy resin and a crosslinked structure-containing polymer. .

The resin sheet is used to fill the gap between the heating element and the adherend and to efficiently transmit heat. At this time, it is necessary to follow the thermal deformation of the heating element and the adherend, which have different coefficients of linear expansion, so the resin sheet is required to have low elasticity.
However, conventional resin sheets may be filled with a large amount of filler to improve thermal conductivity. There has been a problem in that as the content of the filler increases, the elastic modulus of the resin sheet increases.

The present disclosure has been made in view of the above-mentioned conventional circumstances, and provides a resin composition capable of forming a cured product with a low elastic modulus, as well as a resin sheet, a B-stage sheet, a C-stage sheet, and a resin sheet using this resin composition. The purpose of the present invention is to provide a cured product, a resin-coated metal foil, a metal substrate, and a power semiconductor device.

Specific means for achieving the above object are as follows.
<1> A resin composition containing a (meth)acrylic resin containing an optionally blocked isocyanate group and a filler.
<2> The resin composition according to <1>, wherein the (meth)acrylic resin contains a blocked isocyanate group, and the deprotection initiation temperature of the blocked isocyanate group is 40°C or higher.
<3> The resin composition according to <1> or <2>, further containing an epoxy resin.
<4> The resin composition according to any one of <1> to <3>, further containing a curing agent.
<5> The resin composition according to any one of <1> to <4>, further containing a curing accelerator.
<6> The filler contains at least one member selected from the group consisting of alumina, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, magnesite, silica, and graphite <1> to <5> The resin composition according to any one of the above.
<7> The resin composition according to any one of <1> to <6>, wherein the content of the filler is 30% by volume to 90% by volume.
<8> A resin sheet having a resin composition layer containing the resin composition according to any one of <1> to <7>.
<9> A B-stage sheet having a semi-cured resin composition layer containing a semi-cured product of the resin composition according to any one of <1> to <7>.
<10> A C-stage sheet having a cured resin composition layer containing a cured product of the resin composition according to any one of <1> to <7>.
<11> A cured product of the resin composition according to any one of <1> to <7>.
<12> A resin comprising a metal foil and a semi-cured resin composition layer containing a semi-cured resin composition according to any one of <1> to <7>, disposed on the metal foil. With metal foil.
<13> A metal support, a cured resin composition layer containing a cured product of the resin composition according to any one of <1> to <7> disposed on the metal support, and the cured resin A metal substrate, comprising: a metal plate disposed on a composition layer.
<14> A semiconductor module in which a metal plate, a solder layer, and a semiconductor chip are stacked in this order, a heat dissipation member, and the resin according to <8>, which is disposed between the metal plate and the heat dissipation member of the semiconductor module. A power semiconductor device comprising a cured sheet.

According to the present disclosure, a resin composition capable of forming a cured product with a low elastic modulus, a resin sheet, a B-stage sheet, a C-stage sheet, a cured product, a metal foil with resin, and a metal substrate using this resin composition. and a power semiconductor device can be provided.

1 is a schematic cross-sectional view showing an example of the configuration of a power semiconductor device of the present disclosure. FIG. 3 is a schematic cross-sectional view showing another example of the configuration of the power semiconductor device of the present disclosure.

Hereinafter, embodiments for implementing the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the constituent elements (including elemental steps and the like) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the present disclosure.

In this disclosure, the term "step" includes not only a step that is independent from other steps, but also a step that cannot be clearly distinguished from other steps, as long as the purpose of the step is achieved. .
In the present disclosure, numerical ranges indicated using "~" include the numerical values written before and after "~" as minimum and maximum values, respectively.
In the numerical ranges described step by step in this disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. . Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit of the numerical range may be replaced with the values shown in the Examples.
In the present disclosure, each component may contain multiple types of applicable substances. If there are multiple types of substances corresponding to each component in the composition, the content rate or content of each component is the total content rate or content of the multiple types of substances present in the composition, unless otherwise specified. means quantity.
In the present disclosure, the particles corresponding to each component may include multiple types of particles. When a plurality of types of particles corresponding to each component are present in the composition, the particle diameter of each component means a value for a mixture of the plurality of types of particles present in the composition, unless otherwise specified.
In this disclosure, the term "layer" includes not only the case where the layer is formed in the entire area when observing the area where the layer exists, but also the case where the layer is formed only in a part of the area. included.
In this disclosure, the term "laminate" refers to stacking layers, and two or more layers may be bonded, or two or more layers may be removable.
In the present disclosure, "(meth)acryloyl group" means at least one of acryloyl group and methacryloyl group, "(meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acrylate" means acrylic and methacrylate.
In the present disclosure, the average thickness (also referred to as the average thickness value) of a layer or laminate is a value given as the arithmetic mean value of the thicknesses measured at five points of the target layer or laminate.
The thickness of a layer or laminate can be measured using a micrometer or the like. In the present disclosure, when the thickness of a layer or laminate can be directly measured, it is measured using a micrometer. On the other hand, when measuring the thickness of one layer or the total thickness of multiple layers that make up part of a laminate, use an electron microscope to observe a cross section parallel to the stacking direction of the laminate. do.

<Resin composition>
The resin composition of the present disclosure contains a (meth)acrylic resin containing an optionally blocked isocyanate group (hereinafter sometimes referred to as a specific acrylic resin) and a filler. The resin composition of the present disclosure may contain components other than the specific acrylic resin and filler.
According to the resin composition of the present disclosure, it is possible to form a cured product with a low elastic modulus. The reason for this is not clear, but since the resin composition contains a specific acrylic resin that is more flexible than epoxy resin, it is possible to lower the elastic modulus of the cured product obtained by curing the resin composition. It is presumed that it will be.

The components constituting the resin composition of the present disclosure will be described below.

(Specified acrylic resin)
The resin composition of the present disclosure contains a specific acrylic resin. The specific acrylic resin is not particularly limited as long as it contains an isocyanate group that may be blocked and contains a structural unit derived from at least one of an acrylic monomer and a methacrylic monomer.
The specific acrylic resin is a monomer containing a first monomer represented by the following formula (1) and a second monomer that is copolymerizable with the first monomer and has an optionally blocked isocyanate group. It may also be a (meth)acrylic resin obtained by polymerizing components.

In formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 30 carbon atoms.
The alkyl group represented by R ² may be linear or branched. The alkyl group represented by R ² preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and still more preferably 1 to 5 carbon atoms.

In other words, the first monomer is an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 30 carbon atoms at the end of an ester group. The first monomer includes methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, Octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tetradecyl (meth)acrylate , hexadecyl (meth)acrylate, octadecyl (meth)acrylate (stearyl (meth)acrylate), docosyl (meth)acrylate (behenyl (meth)acrylate), tetracosyl (meth)acrylate, hexacosyl (meth)acrylate, octacosyl (meth)acrylate etc. These first monomers may be used alone or in combination of two or more.
The first monomer is preferably at least one selected from the group consisting of ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and methyl (meth)acrylate.

From the viewpoint of flexibility, the content of the first monomer is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 75 parts by mass or more, based on 100 parts by mass of the monomer components, such as It may be 98 parts by mass or less.

The second monomer is a monomer having an optionally blocked isocyanate group. A blocked isocyanate group (hereinafter sometimes referred to as a blocked isocyanate group) is an isocyanate group blocked (protected) with a blocking agent (protective group) that can be removed by heat, and is represented by the following formula (3). It is expressed as
From the viewpoint of reactivity control in the resin sheet manufacturing process and storage stability, the isocyanate group is preferably a blocked isocyanate group.

In formula (3), B represents a protecting group, and * represents a bond.

The deprotection initiation temperature of the protecting group in the blocked isocyanate group is preferably 40°C or higher, more preferably 60°C or higher, even more preferably 80°C or higher, and particularly preferably 90°C or higher. preferable.
In this disclosure, the deprotection onset temperature is measured by differential scanning calorimetry.
In the blocked isocyanate group, under deprotection conditions (at a temperature equal to or higher than the deprotection initiation temperature), a substitution reaction between a blocking agent (protective group) and a curing agent described below may occur. Alternatively, the blocked isocyanate group can be deprotected to generate an isocyanate group, and the isocyanate group can react with a curing agent described below.

Blocking agents for blocked isocyanate groups include oximes such as formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, and cyclohexanone oxime; pyrazoles such as pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole; ε- Lactams such as caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; Mercaptans such as thiophenol, methylthiophenol, and ethylthiophenol; Acid amides such as acetamide and benzamide; Succinimide, malein Imides such as acid imides; and the like.

The second monomer is preferably a monomer having a blocked isocyanate group and a (meth)acryloyl group ((meth)acrylic monomer having a blocked isocyanate group). The second monomer is preferably a monomer represented by the following formula (4).

In formula (4), R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkylene group, and B represents a protecting group.

The alkylene group represented by R ⁶ may be linear or branched. The alkylene group represented by R ⁶ preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 6 carbon atoms, and particularly 1 to 4 carbon atoms. preferable.

Examples of the second monomer include 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate and 2-([1'-methylpropylideneamino]carboxyamino)ethyl methacrylate. These second monomers may be used alone or in combination of two or more.

When the weight average molecular weight (details will be described later) of the specific acrylic resin is 200,000 or more, the content of the second monomer is preferably determined based on 100 parts by mass of the monomer component from the viewpoint of improving the heat resistance of the cured product. is 2 parts by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more.

When the weight average molecular weight (details will be described later) of the specific acrylic resin is 100,000 or less, the content of the second monomer is determined based on 100 parts by mass of the monomer component, from the viewpoint of improving the curability of the resin composition. Preferably it is 2 parts by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more.

Regardless of the weight average molecular weight of the specific acrylic resin (details will be described later), the content of the second monomer is determined to be 2 parts by mass per 100 parts by mass of the monomer component, from the viewpoint of keeping the crosslinking density low and reducing the storage modulus. The amount may be 3 parts by weight or more, 3 parts by weight or more, 5 parts by weight or more, or 7 parts by weight or more, and may be 35 parts by weight or less, preferably 30 parts by weight or less, and more preferably 25 parts by weight or less.

In addition to the first monomer and the second monomer, the monomer component can further contain a monomer other than the first monomer and the second monomer, if necessary. Monomers other than the first monomer and the second monomer include cycloalkyl (meth)acrylates (hereinafter referred to as , sometimes referred to as the third monomer). The third monomer may be used alone or in combination of two or more.

In one embodiment, the monomer component contains only a first monomer, a second monomer, and an optional third monomer. In other words, in one embodiment, the monomer component does not contain monomers other than the first monomer, the second monomer, and the third monomer (for example, a (meth)acrylic monomer having a siloxane skeleton). In one embodiment, the monomer component may contain only the first monomer and the second monomer, and in another embodiment, the monomer component may contain only the first monomer, the second monomer, and the third monomer. It's fine.
The content of other monomers other than the first monomer, second monomer, and optionally used third monomer in the monomer component does not depend on the weight average molecular weight of the specific acrylic resin (details will be described later). The amount is preferably 30 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 0 parts by weight, based on 100 parts by weight of the monomer component.

The specific acrylic resin is obtained by polymerizing monomer components including a first monomer, a second monomer, a third monomer used as necessary, and the like. The polymerization method can be appropriately selected from known polymerization methods such as various radical polymerizations, and may be, for example, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, or the like.

When using the suspension polymerization method, a dispersion liquid is prepared by mixing monomer components serving as raw materials, a polymerization initiator, a chain transfer agent added as necessary, water, and a suspending agent.

Examples of the suspending agent include water-soluble polymers such as polyvinyl alcohol, methylcellulose, and polyacrylamide, and sparingly soluble inorganic substances such as calcium phosphate and magnesium pyrophosphate. Among these, water-soluble polymers such as polyvinyl alcohol are preferably used.

The amount of the suspending agent is preferably 0.005 parts by mass to 1 part by mass, more preferably 0.01 parts by mass to 0.07 parts by mass, based on 100 parts by mass of the total amount of monomer components as raw materials. . When using the suspension polymerization method, a chain transfer agent such as a mercaptan compound, thioglycol, carbon tetrachloride, α-methylstyrene dimer, etc. may be further added as necessary. The polymerization temperature is preferably 0°C to 200°C, more preferably 40°C to 120°C, even more preferably 50°C to 100°C.

When using the solution polymerization method, examples of solvents used include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, and carbon tetrachloride. Examples include chlorine-based solvents such as 2-propanol, alcohol-based solvents such as 2-butanol, and the like.
From the viewpoint of polymerizability of the specific acrylic resin obtained, the solid content concentration in the solution at the start of solution polymerization is preferably 30% by mass to 80% by mass, more preferably 40% to 70% by mass, and even more preferably 45% by mass. % to 55% by mass. The polymerization temperature is preferably 0°C to 200°C, more preferably 40°C to 120°C, even more preferably 50°C to 100°C.

The polymerization initiator used in each polymerization method can be used without particular limitation as long as it is a radical polymerization initiator. Examples of the radical polymerization initiator include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy -3,3,5-trimethylcyclohexane, organic peroxides such as t-butylperoxyisopropyl carbonate, azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1- Examples include azo compounds such as carbonitrile and azodibenzoyl.

From the viewpoint of sufficiently polymerizing the monomers, the amount of the polymerization initiator is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0. .1 part by mass or more. The amount of the polymerization initiator to be blended is preferably such that the molecular weight of the specific acrylic resin falls within a suitable range, suppresses decomposition products, and provides suitable adhesive strength, based on 100 parts by mass of the total amount of monomers. The amount is 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less.

The specific acrylic resin obtained as described above has a structural unit derived from the first monomer and a structural unit derived from the second monomer. That is, the resin composition according to one embodiment is an acrylic resin composition containing a first structural unit (a structural unit derived from a first monomer) and a second structural unit (a structural unit derived from a second monomer). Contains resin.

The first structural unit is represented by the following formula (2).

In formula (2), R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents an alkyl group having 1 to 30 carbon atoms. Specific examples of the alkyl group represented by R ⁴ are the same as those for R ² in formula (1).

From the viewpoint of flexibility, the content of the first structural unit is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably The amount may be 75 parts by mass or more and, for example, 98 parts by mass or less.

The second structural unit has an isocyanate group that may be blocked. The second structural unit is, for example, a structural unit derived from the above-mentioned monomer having a blocked isocyanate group.

The second structural unit is preferably a structural unit represented by the following formula (5).

In formula (5), R ⁷ represents a hydrogen atom or a methyl group, and R ⁸ represents a monovalent organic group containing a blocked isocyanate group. The protecting group for the blocked isocyanate group may be the same group as the protecting group for the blocked isocyanate group possessed by the second monomer described above.

The second structural unit is preferably represented by the following formula (6).

In formula (6), R ⁷ represents a hydrogen atom or a methyl group, R ⁹ represents an alkylene group, and B represents a protecting group. Specific examples of the alkylene group represented by R ⁹ are the same as those for R ⁶ in formula (4), and specific examples of the protecting group represented by B are the same as those for B in formula (3). The same is true.

When the weight average molecular weight (details will be described later) of the specific acrylic resin is 200,000 or more, the content of the second structural unit is determined by all structural units constituting the specific acrylic resin from the viewpoint of improving the heat resistance of the cured product. The amount is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, still more preferably 5 parts by weight or more, particularly preferably 7 parts by weight or more, based on 100 parts by weight.

When the weight average molecular weight (details will be described later) of the specific acrylic resin is 100,000 or less, the content of the second structural unit is determined from the viewpoint of improving the curability of the resin composition. The amount is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, particularly preferably 7 parts by mass or more, per 100 parts by mass.

The content of the second structural unit is determined from the viewpoint of keeping the crosslinking density low and reducing the storage modulus, regardless of the weight average molecular weight of the specific acrylic resin (details will be described later). Based on 100 parts by mass, the amount may be 2 parts by mass or more, 3 parts by mass or more, 5 parts by mass or more, or 7 parts by mass or more, and may be 35 parts by mass or less, preferably 30 parts by mass or less, more preferably is 25 parts by mass or less.

In addition to the first structural unit and the second structural unit, the specific acrylic resin can further contain a structural unit other than the first structural unit and the second structural unit, if necessary. The structural units other than the first structural unit and the second structural unit may be structural units derived from the above-mentioned third monomer (third structural unit), etc.

In one embodiment, the specific acrylic resin contains only a first structural unit, a second structural unit, and, if necessary, a third structural unit. In other words, in one embodiment, the specific acrylic resin includes structural units other than the first structural unit, the second structural unit, and the third structural unit (for example, those derived from a (meth)acrylic monomer having a siloxane skeleton). structural unit). In one embodiment, the specific acrylic resin may contain only the first structural unit and the second structural unit, and in another embodiment, the specific acrylic resin may contain the first structural unit, the second structural unit, and the third structural unit. May contain only structural units.
The content of other structural units other than the first structural unit, second structural unit, and optionally used third structural unit in the specific acrylic resin is determined by the weight average molecular weight of the specific acrylic resin (for details, see (described later), the amount is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 0 parts by mass, based on 100 parts by mass of all structural units.

The specific acrylic resin may be a random copolymer, a block copolymer, or a graft copolymer.

In one embodiment, the specific acrylic resin has a weight average molecular weight of preferably 200,000 or more, more preferably 250,000 or more from the viewpoint of improving the strength of the cured product. The weight average molecular weight of the specific acrylic resin is preferably 2,000,000 or less, more preferably 1,500,000 or less, still more preferably 1,000,000 or less, from the viewpoint of ease of handling of the resin composition.

In another embodiment, the specific acrylic resin has a weight average molecular weight of preferably 100,000 or less, more preferably 70,000 or less, and still more preferably 50,000 or less, from the viewpoint of reducing the viscosity of the resin composition. In this case, the weight average molecular weight of the specific acrylic resin may be, for example, 5000 or more.

In the present disclosure, the weight average molecular weight (Mw) of a specific acrylic resin refers to a value measured by gel permeation chromatography (GPC). Mw was measured by GPC using Tosoh Corporation's G2000HXL and 3000HXL as analytical GPC columns, using tetrahydrofuran as the mobile phase, with a sample concentration of 0.2% by mass, and a flow rate of 1.0mL/min. I do. A calibration curve is created using a polystyrene standard sample, and Mw is calculated using a polystyrene equivalent value.

From the viewpoint of flexibility, the content of the specific acrylic resin is preferably 1% by mass to 30% by mass, more preferably 2% by mass to 20% by mass, and 3% by mass to 3% by mass, based on the total resin composition. More preferably, the content is 10% by mass.

(filling material)
The resin composition of the present disclosure contains a filler. The filler may be electrically non-conductive or electrically conductive. The use of a non-conductive filler tends to suppress a decrease in the insulation properties of the cured product. Furthermore, by using a conductive filler, the thermal conductivity of the cured product tends to be further improved.

Specifically, non-conductive fillers include aluminum oxide (alumina), magnesium oxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, zinc oxide, magnesite, silica (silicon dioxide), silicon oxide, and hydroxide. Examples include aluminum and barium sulfate. Examples of the conductive filler include gold, silver, nickel, copper, and graphite. Among them, from the viewpoint of thermal conductivity, the filler may contain at least one member selected from the group consisting of alumina, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, magnesite, silica, and graphite. Preferably, at least one selected from the group consisting of boron nitride and aluminum oxide (alumina) is more preferable. One filler may be used alone, or two or more fillers may be used in combination. For example, a combination of aluminum oxide and boron nitride may be used as the filler.

It is preferable to use a mixture of two or more fillers having different volume average particle diameters. This allows the small particle size filler to be packed into the voids of the large particle size filler, resulting in higher thermal conductivity than when only a single particle size filler is used. It becomes possible to demonstrate the efficiency.

The volume average particle diameter (D50) of the filler can be measured using a laser diffraction method. For example, the filler in the resin composition is extracted and measured using a laser diffraction scattering particle size distribution analyzer (eg, Beckman Coulter, trade name: LS230). Specifically, the filler is extracted from the resin composition using an organic solvent, nitric acid, aqua regia, etc., sufficiently dispersed using an ultrasonic disperser, etc., and the volume cumulative particle size distribution curve of this dispersion is measured. .
The volume average particle diameter (D50) refers to the particle diameter at which the cumulative volume is 50% from the small diameter side in the volume cumulative particle size distribution curve obtained from the above measurement.

The content of the filler is not particularly limited. Among them, from the viewpoint of thermal conductivity, the content of the filler is preferably 30% to 90% by volume, and preferably 60% to 90% by volume, when the total solid content of the resin composition is 100% by volume. More preferably, it is 85% by volume.
If the content of the filler is 30% by volume or more, it tends to be possible to achieve higher thermal conductivity. On the other hand, when the content of the filler is 90% by volume or less, it tends to suppress a decrease in flexibility and a decrease in insulation properties of the cured product of the resin composition.

The mass-based content of the filler is preferably 30% to 85% by mass of the entire resin composition, more preferably 35% to 80% by mass, and 40% to 75% by mass. It is even more preferable that there be.

(Epoxy resin)
The resin composition of the present disclosure may contain an epoxy resin from the viewpoint of improving the electrical insulation properties, heat resistance, etc. of the cured product.
The type of epoxy resin is not particularly limited and can be selected depending on the desired characteristics of the resin composition. Specifically, the epoxy resin is at least selected from the group consisting of phenol compounds such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, and bisphenol F, and naphthol compounds such as α-naphthol, β-naphthol, and dihydroxynaphthalene. Novolak-type epoxy resin (phenol novolak) is an epoxidized novolak resin obtained by condensing or co-condensing one type of phenolic compound with an aliphatic aldehyde compound such as formaldehyde, acetaldehyde, or propionaldehyde under an acidic catalyst. type epoxy resin, orthocresol novolak type epoxy resin, etc.); Triphenylmethane type phenol resin obtained by condensing or co-condensing the above phenolic compound with an aromatic aldehyde compound such as benzaldehyde or salicylaldehyde under an acidic catalyst. A triphenylmethane type epoxy resin which is an epoxidized product; a copolymerized epoxy resin which is an epoxidized novolac resin obtained by cocondensing the above phenol compound and naphthol compound with an aldehyde compound under an acidic catalyst; Diphenylmethane type epoxy resins which are diglycidyl ethers such as bisphenol A and bisphenol F; biphenyl type epoxy resins which are diglycidyl ethers of alkyl-substituted or unsubstituted biphenols; stilbene type epoxy resins which are diglycidyl ethers of stilbene type phenol compounds; Sulfur atom-containing epoxy resins that are diglycidyl ethers such as bisphenol S; epoxy resins that are glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; polyhydric carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid. Glycidyl ester type epoxy resin, which is the glycidyl ester of a compound; Glycidylamine type epoxy resin, which has the active hydrogen bonded to the nitrogen atom of aniline, diaminodiphenylmethane, isocyanuric acid, etc. replaced with a glycidyl group; vinylcyclohexene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy) Alicyclic epoxy resin such as cyclohexane-m-dioxane; para-xylylene-modified epoxy resin which is the glycidyl ether of para-xylylene-modified phenol resin; metaxylylene-modified epoxy resin which is the glycidyl ether of metaxylylene-modified phenol resin; glycidyl ether of terpene-modified phenol resin. Terpene-modified epoxy resin; dicyclopentadiene-modified epoxy resin, which is the glycidyl ether of dicyclopentadiene-modified phenol resin; cyclopentadiene-modified epoxy resin, which is the glycidyl ether of cyclopentadiene-modified phenol resin; glycidyl ether of polycyclic aromatic ring-modified phenol resin. Certain polycyclic aromatic ring-modified epoxy resins; naphthalene-type epoxy resins that are glycidyl ethers of naphthalene ring-containing phenolic resins; halogenated phenol novolac-type epoxy resins; hydroquinone-type epoxy resins; trimethylolpropane-type epoxy resins; Linear aliphatic epoxy resins obtained by oxidation with peracids; aralkyl-type epoxy resins obtained by epoxidizing aralkyl-type phenolic resins such as phenol-aralkyl resins and naphthol-aralkyl resins; and the like. These epoxy resins may be used alone or in combination of two or more.

When the resin composition contains an epoxy resin, the content of the epoxy resin is preferably 0.1% to 20% by mass of the entire resin composition, from the viewpoint of improving the heat resistance of the cured product. It is more preferably from .1% by mass to 10% by mass, and even more preferably from 0.2% by mass to 5% by mass.

(hardening agent)
The resin composition of the present disclosure may further contain a curing agent from the viewpoint of improving the heat resistance of the cured product.
When the isocyanate group is blocked, the curing agent can react with the blocked isocyanate group at a temperature equal to or higher than the deprotection initiation temperature of the blocked isocyanate group contained in the second monomer (second structural unit). More specifically, the curing agent causes a substitution reaction with the blocking agent (protective group) on the blocked isocyanate group contained in the second monomer (second structural unit) at a temperature equal to or higher than the deprotection initiation temperature. It is a hardening agent to obtain. Alternatively, the curing agent is a curing agent that can react with an isocyanate group generated by elimination (deprotection) of the blocking agent in the blocked isocyanate group contained in the second monomer (second structural unit). .

The curing agent is preferably at least one selected from the group consisting of amine curing agents, alcohol curing agents, and phenolic curing agents, from the viewpoint of increasing the reactivity between the specific acrylic resin and the curing agent and speeding up the curing speed. It is one type of compound. The curing agent may have a function of crosslinking specific acrylic resins and can also be called a crosslinking agent.
When the resin composition contains an epoxy resin, the curing agent may react not only with isocyanate groups but also with epoxy groups contained in the epoxy resin.

Examples of the amine curing agent include aromatic curing agents such as diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenyl ether, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 1,5-diaminonaphthalene, and m-xylylenediamine. Aliphatic amines such as amines, ethylenediamine, diethylenediamine, diethylenetriamine, hexamethylenediamine, isophoronediamine, bis(4-amino-3-methyldicyclohexyl)methane, polyetherdiamine; dicyandiamide, 1-(o-tolyl)biguanide, etc. Examples include guanidines.

Examples of alcohol-based curing agents include polyhydric alcohols such as glycerin, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, and diethylene glycol.

The phenolic curing agent is selected from the group consisting of phenolic compounds (e.g. phenol, cresol, xylenol, resorcinol, catechol, bisphenol A and bisphenol F) and naphthol compounds (e.g. α-naphthol, β-naphthol and dihydroxynaphthalene). and an aldehyde compound (for example, formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde) under an acidic catalyst; a novolac resin obtained by condensing or co-condensing at least one of the following: phenol/aralkyl resin; biphenyl/aralkyl type phenolic resins; and naphthol aralkyl resins.

The content of the curing agent is preferably 0.1% to 5% by mass of the entire resin composition, more preferably 0.2% to 3% by mass, and 0.5% to 2% by mass. More preferably, it is expressed in mass %.

(hardening accelerator)
The resin composition of the present disclosure preferably further contains a curing accelerator from the viewpoint of accelerating the reaction between the acrylic resin, the epoxy resin used as needed, and the curing agent.
Examples of the curing accelerator include imidazole curing accelerators, organic phosphorus curing accelerators, tertiary amine curing accelerators, quaternary ammonium salt curing accelerators, and tin catalysts. Among these, tin catalysts such as dibutyltin dilaurate are preferred. Note that these curing accelerators may be used alone or in combination of two or more.

From the viewpoint of moldability, the content of the curing accelerator is preferably 0.01% to 1% by mass, more preferably 0.02% to 0.5% by mass of the entire resin composition. It is preferably 0.05% by mass to 0.3% by mass, more preferably 0.05% by mass to 0.3% by mass.

(Other ingredients)
The resin composition of the present disclosure may contain other components in addition to the above components, as necessary. Examples of other components include a solvent, an elastomer, a silane coupling agent, a dispersant, and an antisettling agent. These components may be used alone or in combination of two or more.

The solvent is not particularly limited as long as it does not inhibit the curing reaction of the resin composition, and commonly used organic solvents can be appropriately selected and used. Specific examples of the solvent include methyl ethyl ketone, cyclohexanone, ethyl lactate, and the like.
When the resin composition contains a solvent, the content of the solvent contained in the resin composition is preferably 10% by mass to 40% by mass, and preferably 10% by mass to 35% by mass of the entire resin composition. is more preferable, and even more preferably 15% by mass to 30% by mass.

The resin composition of the present disclosure preferably contains a silane coupling agent. By including a silane coupling agent, the thermal conductivity and insulation properties of the cured product tend to be further improved.

As the silane coupling agent, a commercially available one may be used. From the viewpoint of compatibility with the specific acrylic resin or curing agent, reduction of heat conduction loss at the interface between the specific acrylic resin and the filler, etc., functional groups such as epoxy groups, amino groups, mercapto groups, ureido groups, and hydroxyl groups are recommended. It is preferable to use a silane coupling agent having the following.

Specifically, examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. Propylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-(2-aminoethyl) Aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-ureidopropyltriethoxysilane. can be mentioned. Also included are silane coupling agent oligomers typified by SC-6000KS2 (manufactured by Hitachi Chemical Techno Service Co., Ltd.).
These silane coupling agents may be used alone or in combination of two or more.

When the resin composition of the present disclosure contains a silane coupling agent, the content of the silane coupling agent in the resin composition is not particularly limited. For example, the content of the silane coupling agent is preferably 0.01% by mass to 0.5% by mass of the entire resin composition.

The silane coupling agent may be contained in the resin composition, and may be present in a state where the surface of the filler is coated, or may be present separately from the filler.

<Physical properties of resin composition>
When the resin composition of the present disclosure contains a solvent, the viscosity of the resin composition at 25°C is preferably 0.5 Pa·s to 5 Pa·s, and preferably 0.5 Pa·s to 4 Pa·s. is more preferable, and even more preferably 1 Pa·s to 3 Pa·s. The viscosity of the resin composition at 25 °C is measured at a temperature of 25 °C at a shear rate of 5.0 ^s using a rotary shear viscometer equipped with a cone plate (40 mm diameter, 0 ° cone angle). refers to value.
Further, the thixotropy index of the resin composition at 25° C. is preferably 3 to 15, more preferably 3.5 to 10, and even more preferably 4 to 7.
The thixotropy index of the resin composition is determined by first setting the temperature of the resin composition to 25°C and calculating the viscosity at a shear rate of 0.5 s ^-1 (η1) and the viscosity at a shear rate of 5.0 s ^-1 (η2). ) and calculate (η1)/(η2). Specifically, the "thixotropy index" is measured as shear viscosity at a temperature of 25° C. using a rotary shear viscometer equipped with a cone plate (diameter 40 mm, cone angle 0°).

<Resin sheet>
The resin sheet of the present disclosure has a resin composition layer containing the resin composition of the present disclosure. The resin composition layer may be one layer or two or more layers. The resin sheet of the present disclosure may further include a release film, if necessary.

For example, the resin composition layer is a varnish-like resin composition (hereinafter also referred to as "resin varnish") prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to a resin composition, and a release film such as a PET film. It can be manufactured by applying it on top and drying it.

The resin varnish can be applied by a known method. Specifically, methods such as comma coating, die coating, lip coating, and gravure coating may be mentioned. Methods for applying resin varnish to form a resin composition layer with a predetermined thickness include the comma coating method in which the object to be coated is passed through a gap, and the die coating method in which the resin varnish is applied from a nozzle at a controlled flow rate. Can be mentioned. When the average thickness of the resin composition layer before drying is 50 μm to 500 μm, it is preferable to use the comma coating method.

The drying method is not particularly limited as long as it can remove at least a portion of the organic solvent contained in the resin varnish, and can be appropriately selected from commonly used drying methods.

The density of the resin composition layer is not particularly limited, and is usually 3.0 g/cm ³ to 3.4 g/cm ³ , and from the viewpoint of achieving both flexibility and thermal conductivity, it is 3.0 g/cm 3 to 3.0 g/cm ³ . It is preferably 3.3 g/cm ³ , more preferably 3.1 g/cm ³ to 3.3 g/cm ³ . The density of the resin composition layer can be adjusted, for example, by adjusting the amount of filler added.

In the present disclosure, when the resin composition layer has two or more resin composition layers, the density of the resin composition layer refers to the average value of the densities of all the resin composition layers. Moreover, when a release film is included in the resin sheet, it refers to the density of the resin composition layer excluding the release film.

The resin sheet preferably has a first resin composition layer containing a resin composition and a second resin composition layer containing a resin composition laminated on the first resin composition layer. . For example, the resin sheet is preferably a laminate of a first resin composition layer formed from a resin composition and a second resin composition layer formed from a resin composition. This allows the dielectric strength to be further improved. The resin compositions forming the first resin composition layer and the second resin composition layer may have the same composition or different compositions. From the viewpoint of thermal conductivity, it is preferable that the resin compositions forming the first resin composition layer and the second resin composition layer have the same composition.

When the resin sheet is a laminate, it is preferably manufactured by overlapping a first resin composition layer and a second resin composition layer formed from a resin composition. With such a configuration, the dielectric breakdown voltage tends to be further improved.

For example, this can be considered as follows. In other words, by stacking two resin composition layers, the thinner areas (pinholes or voids) that may exist in one resin composition layer are compensated for by the other resin composition layer. . This can be considered to increase the minimum insulation thickness and further improve the dielectric strength voltage. The probability of pinholes or voids occurring in the resin sheet manufacturing method is not high, but by stacking two resin composition layers, the probability that the thin parts will overlap becomes the square of that, and the number of pinholes or voids becomes zero. It will get closer. Since dielectric breakdown occurs at the weakest point in terms of insulation, it can be considered that by stacking two resin composition layers, the effect of further improving the dielectric strength voltage can be obtained. Furthermore, by stacking two resin composition layers, the probability of contact between the fillers increases, and it can be considered that the effect of further improving the thermal conductivity when formed into a cured product is also produced.

The method for producing a resin sheet includes the steps of stacking a second resin composition layer formed from a resin composition on a first resin composition layer formed from a resin composition to obtain a laminate; It is preferable to include a step of heating and pressurizing the laminate. By using such a manufacturing method, the dielectric breakdown voltage tends to be further improved.

The thickness of the resin sheet can be appropriately selected depending on the purpose. The average thickness of the resin composition layer can be, for example, 50 μm to 350 μm, and preferably 60 μm to 300 μm from the viewpoint of thermal conductivity, insulation, and sheet flexibility.

<B stage sheet>
The B-stage sheet of the present disclosure has a semi-cured resin composition layer containing a semi-cured product of the resin composition of the present disclosure. The B-stage sheet can be manufactured, for example, by a manufacturing method that includes a step of heat-treating the resin composition layer in the resin sheet of the present disclosure to a B-stage state.

From the viewpoint of handling properties, it is preferable to convert the resin composition layer, which is the A stage of the resin sheet, into a B stage to obtain a B stage sheet.

The heat treatment conditions for converting the A-stage resin composition layer to the B-stage are not particularly limited as long as the resin composition layer can be semi-cured to the B-stage state, and are appropriately selected depending on the structure of the resin composition. be able to. For the purpose of eliminating voids in the resin composition layer that are generated when applying the resin composition, it is preferable to apply a heat treatment method selected from hot vacuum pressing, hot roll lamination, and the like. Thereby, a flat B-stage sheet can be efficiently manufactured. Specifically, for example, the resin composition layer can be semi-cured to a B-stage state by heating and pressurizing it at 80° C. to 180° C. for 1 second to 3 minutes under reduced pressure (eg, 1 kPa). Further, the pressurizing pressure can be 0.1 MPa to 20 MPa.

The average thickness of the B-stage sheet can be appropriately selected depending on the purpose, and can be, for example, 50 μm to 350 μm, and from the viewpoint of thermal conductivity, insulation, and sheet flexibility, 60 μm to 300 μm. It is preferable to do so. Moreover, a B-stage sheet can also be produced by heating and pressurizing a laminated state of two or more resin sheets.

<C stage sheet>
The C-stage sheet of the present disclosure has a cured resin composition layer containing a cured product of the resin composition of the present disclosure. The C-stage sheet can be manufactured, for example, by a manufacturing method that includes a step of heat-treating a resin sheet or a B-stage sheet to a C-stage state. The conditions for heat-treating the resin sheet or B-stage sheet are not particularly limited as long as the resin composition layer or semi-cured resin composition layer can be cured to the C-stage state, and are appropriately selected depending on the configuration of the resin composition. be able to. From the viewpoint of suppressing the generation of voids in the C-stage sheet and improving the heat resistance of the C-stage sheet, it is preferable to apply a heat treatment method such as thermal vacuum pressing. Thereby, a flat C-stage sheet can be efficiently manufactured. Specifically, the resin composition layer or semi-cured resin composition layer is cured to a C-stage state by heating and pressurizing the resin composition layer or the semi-cured resin composition layer at 100° C. to 250° C. for 1 minute to 60 minutes at 0.1 MPa to 30 MPa. I can do it.

The average thickness of the C-stage sheet can be appropriately selected depending on the purpose, and can be, for example, 50 μm to 350 μm, and from the viewpoint of thermal conductivity, insulation, and sheet flexibility, 60 μm to 300 μm. It is preferable to do so. Moreover, a C-stage sheet can also be produced by heating and pressurizing a laminated state of two or more layers of resin sheets or B-stage sheets.

<Cured product>
The cured product of the present disclosure is a cured product of the resin composition of the present disclosure. The method for curing the resin composition is not particularly limited, and any commonly used method can be appropriately selected. For example, a cured product of the resin composition can be obtained by heat-treating the resin composition.
There are no particular limitations on the method of heat treating the resin composition, and there are no particular limitations on the heat treatment conditions. The temperature range of the heat treatment can be appropriately selected depending on the type of specific acrylic resin and curing agent that constitute the resin composition. Further, the time for the heat treatment is not particularly limited and is appropriately selected depending on the shape, thickness, etc. of the cured product.

<Metal foil with resin>
The resin-coated metal foil of the present disclosure includes a metal foil and a semi-cured resin composition layer containing a semi-cured product of the resin composition of the present disclosure disposed on the metal foil. The semi-cured resin composition layer is obtained by heat-treating the resin composition to bring it into a B-stage state.

Examples of the metal foil include gold foil, copper foil, aluminum foil, etc., and copper foil is generally used.
The average thickness of the metal foil is not particularly limited, and may be, for example, 1 μm to 500 μm. Note that by using a metal foil with a thickness of 20 μm or less, the flexibility of the resin-coated metal foil tends to be further improved.
As a metal foil, the intermediate layer is made of nickel, nickel-phosphorus alloy, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc., and a 0.5 μm to 15 μm copper layer is provided on one side of the intermediate layer. It is also possible to use a composite foil with a three-layer structure in which a copper layer of 10 μm to 300 μm is provided on the other side of the intermediate layer, or a composite foil with a two-layer structure in which an aluminum foil and a copper foil are combined.

Metal foil with resin is produced by, for example, applying a resin composition (which may be a resin varnish) onto the metal foil and drying it to form an A-stage resin composition layer, which is then heat-treated to form a resin composition layer. It can be manufactured by bringing the layer into a B-stage state. The method for forming the resin composition layer is as described above.

The conditions for manufacturing the resin-coated metal foil are not particularly limited. In the resin composition layer after drying, it is preferable that 80% by mass or more of the organic solvent used in the resin varnish is removed. The drying temperature is about 60° C. to 180° C., and the drying time can be appropriately selected in consideration of gelation and is not particularly limited. The amount of resin varnish to be applied is preferably such that the average thickness of the resin composition layer after drying is 50 μm to 350 μm, and more preferably such that the average thickness is 60 μm to 300 μm. The resin composition layer after drying becomes a B-stage state by being heat-treated. The conditions for heat treating the resin composition layer are the same as those for the B-stage sheet.

<Metal substrate>
The metal substrate of the present disclosure includes a metal support, a cured resin composition layer containing a cured product of the resin composition of the present disclosure disposed on the metal support, and a cured resin composition layer disposed on the cured resin composition layer. A metal plate.

The material, thickness, etc. of the metal support and metal plate are appropriately selected depending on the purpose. Specifically, metal such as copper, aluminum, iron, etc. can be used, and the thickness can be set to 0.3 mm to 5 mm.

The metal substrate of the present disclosure can be manufactured, for example, as follows.
A resin composition layer is formed by applying a resin composition on a metal support such as aluminum in the same manner as in the case of resin-coated metal foil, etc., and drying it, and then placing a metal plate on the resin composition layer. A metal substrate can be manufactured by subjecting this to heat and pressure treatment to cure the resin composition layer. In addition, after laminating the resin-coated metal foil onto the metal support so that the semi-cured resin composition layer faces the metal support, this is heated and pressurized to cure the semi-cured resin composition layer. It can also be manufactured by

<Power semiconductor device>
The power semiconductor device of the present disclosure includes a semiconductor module in which a metal plate, a solder layer, and a semiconductor chip are stacked in this order, a heat dissipation member, and the present disclosure disposed between the metal plate and the heat dissipation member of the semiconductor module. and a cured resin sheet.
In the power semiconductor device, only the semiconductor module portion may be sealed with a sealant or the like, or the entire power semiconductor module may be molded with a molding resin or the like. Examples of power semiconductor devices will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a power semiconductor device. In FIG. 1, in a semiconductor module in which a metal plate 106, a solder layer 110, and a semiconductor chip 108 are laminated in this order, a cured resin sheet 102 is placed between a metal plate 106 and a heat dissipation base substrate 104, and the semiconductor module This portion is sealed with a sealing material 114.
Moreover, FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the power semiconductor device. In FIG. 2, in a semiconductor module in which a metal plate 106, a solder layer 110, and a semiconductor chip 108 are laminated in this order, a cured resin sheet 102 is placed between a metal plate 106 and a heat dissipation base substrate 104, and the semiconductor module and a heat dissipation base substrate 104 are molded with mold resin 112.

In this way, the cured resin sheet of the present disclosure can be used as a heat-radiating adhesive layer between a semiconductor module and a heat-radiating base substrate, as shown in FIG. Furthermore, even when the entire power semiconductor device is molded as shown in FIG. 2, it can be used as a heat dissipation material between the heat dissipation base substrate and the metal plate.

Hereinafter, the present disclosure will be specifically explained using examples, but the present disclosure is not limited to these examples. The materials used for preparing the resin composition and their abbreviations are shown below.

[Example of synthesis of specific acrylic resin]
Acrylic resin 1A and acrylic resin 1B were synthesized by a known solution polymerization method as follows.

(Synthesis of acrylic resin 1A containing blocked isocyanate groups)
A 500 mL flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, an outlet tube, and a heating jacket was used as a reactor, and the monomers were 27 g of ethyl acrylate, 58 g of butyl acrylate, and 2-[(3,5-dimethylpyrazolyl)carbonylamino]. Mix 15 g of ethyl methacrylate (deprotection starting temperature: 90°C) and 118 g of methyl ethyl ketone as a solvent, add to the reactor, stir at room temperature (25°C) at 200 rotations/min, and add 100 mL of nitrogen for 1 hour. /min. Thereafter, the temperature was raised to 65°C, and one hour after the completion of the temperature rise, a solution of 0.3 g of azobisisobutyronitrile dissolved in 4 mL of methyl ethyl ketone was added to the reactor to start the reaction. Thereafter, the mixture was stirred at an internal temperature of 65° C. and reacted for 4 hours. Thereafter, the temperature was raised to 80°C, and the reaction was further continued for 2 hours. Thereafter, the solvent was removed and dried to obtain acrylic resin 1A. The Mw of acrylic resin 1A was 286,000.

(Synthesis of acrylic resin 1B containing blocked isocyanate groups)
A 500 mL flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, an outlet tube, and a heating jacket was used as a reactor, and the monomers were 27 g of ethyl acrylate, 58 g of butyl acrylate, and 2-[(3,5-dimethylpyrazolyl)carbonylamino]. 15 g of ethyl methacrylate and 110 g of 2-propanol as a solvent were mixed, added to a reactor, and stirred at room temperature (25° C.) at a stirring speed of 200 rotations/min, and nitrogen was flowed at a rate of 100 mL/min for 1 hour. Thereafter, the temperature was raised to 70°C, and one hour after the completion of the temperature rise, a solution of 0.25 g of azobisisobutyronitrile dissolved in 2 mL of methyl ethyl ketone was added to the reactor to start the reaction. Thereafter, 9.7 g of 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate was added dropwise to the reactor over 1 hour and 30 minutes, followed by further reaction for 2 hours. Thereafter, the temperature was raised to 80° C., and a solution of 0.05 g of azobisisobutyronitrile dissolved in 1 mL of methyl ethyl ketone was added to the reactor, stirred at an internal temperature of 80° C., and reacted for 2 hours. Thereafter, the solvent was removed and dried to obtain acrylic resin 1B. The Mw of acrylic resin 1B was 34,000.

(Epoxy resin)
・Epoxy resin 1: biphenyl type epoxy resin, epoxy equivalent: 172 g/eq
・Epoxy resin 2: [4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropoxy)benzoate, epoxy equivalent: 212 g/eq, in JP-A No. 2011-74366 Epoxy resin with mesogenic structure prepared by the method described]

(hardening agent)
・Curing agent 1: biphenyl aralkyl type phenol resin, hydroxyl group equivalent: 136 g/eq
・Curing agent 2: Catechol resorcinol novolac resin (CRN) synthesized by the following method

(CRN synthesis method)
627 g of resorcinol, 33 g of catechol, 316.2 g of a 37% by mass formaldehyde aqueous solution, 15 g of oxalic acid, and 300 g of water were placed in a 3 L separable flask equipped with a stirrer, a condenser, and a thermometer, and heated in an oil bath for 100 g. The temperature was raised to ℃. The mixture was refluxed at around 104°C, and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature inside the flask was raised to 170°C while water was distilled off. The reaction was continued for 8 hours while maintaining the temperature at 170°C. After the reaction, it was concentrated for 20 minutes under reduced pressure to remove water, etc. in the system, and the target product, catechol resorcinol novolac resin (CRN) was obtained (mass-based charging ratio: catechol/resorcinol = 5/95, cyclohexanone 50% by mass).
The obtained CRN contained 35% by mass of an unreacted monomer component (resorcinol), had a hydroxyl equivalent: 62 g/eq, a number average molecular weight: 422, and a weight average molecular weight: 564.

(filling material)
・AA-04 [Alumina particles, D50: 0.4 μm]
・AA-3 [Alumina particles, D50: 3μm]
・AA-18 [Alumina particles, D50: 18 μm]

(hardening accelerator)
・Curing accelerator 1: dibutyltin dilaurate ・Curing accelerator 2: Triphenylphosphine

(solvent)
・CHN: Cyclohexanone ・MEK: Methyl ethyl ketone

(Silane coupling agent)
・KBM-573: N-phenyl-3-aminopropyltrimethoxysilane

(Support)
・PET film [average thickness 50μm]
・Copper foil [average thickness: 105μm]

[Example 1]
(Adjustment of resin composition)
6.7% by mass of acrylic resin 1A, 1.0% by mass of curing agent 1, 0.1% by mass of curing accelerator 1, 7.3% by mass of AA-04 as a filler, AA- 17.4% by mass of 3, 48.0% by mass of AA-18, 0.3% by mass of KBM-573 as an additive, and 19.2% by mass of MEK as a solvent were mixed to create a varnish. A resin composition was prepared.
The density of the alumina (AA-04, AA-3, AA-18) is 3.98 g/cm ³ and the density of the resin (mixture of acrylic resin and curing agent) is 1.20 g/cm ³ . The ratio of the filler to the total solid volume was calculated to be 74% by volume.

(Preparation of A-stage resin sheet)
Using a PET film as a support, the resin composition was coated onto the PET film using a table coater (Tester Sangyo Co., Ltd.). The film was dried by heating in a box oven at 70° C. for 10 minutes to obtain an A-stage sheet in which a resin composition layer with an average thickness of 200 μm was formed on the PET film in an A-stage state.

(Preparation of C stage sheet for evaluation)
Next, a copper foil was placed on the dried A-stage sheet, and hot pressurized using a vacuum press (press temperature: 100°C, degree of vacuum: 1 kPa, press pressure: 0.5 MPa, press time: 2 minutes). ) to bring the resin sheet to a B-stage state.
Next, the PET film was peeled off from the resin sheet with the copper foil in the B stage state, and the copper foil was placed on top of the PET film. In this state, vacuum thermocompression bonding was performed using a vacuum press (press temperature: 120° C., degree of vacuum: 1 kPa, press pressure: 0.5 MPa, press time: 10 minutes) to obtain a C-stage sheet with copper foil.

[Example 2]
(Adjustment of resin composition)
2.3% by mass of acrylic resin 1A, 2.3% by mass of acrylic resin 1B, 0.6% by mass of curing agent 1, 0.2% by mass of curing accelerator 1, and AA- as a filler. 7.0% by mass of 04, 16.9% by mass of AA-3, 46.6% by mass of AA-18, 0.3% by mass of KBM-573 as an additive, and 23% of MEK as a solvent. .8% by mass was mixed to prepare a varnish-like resin composition.
The density of the alumina (AA-04, AA-3, AA-18) is 3.98 g/cm ³ and the density of the resin (mixture of acrylic resin and curing agent) is 1.20 g/cm ³ . The ratio of the filler to the total solid volume was calculated to be 80% by volume.

(Preparation of A-stage resin sheet)
An A-stage resin sheet was produced in the same manner as in Example 1.

(Preparation of C stage sheet for evaluation)
A C-stage sheet for evaluation was produced in the same manner as in Example 1, and its thermal conductivity was measured.

[Comparative example 1]
(Preparation of resin composition)
0.84% by mass of epoxy resin 1, 4.18% by mass of epoxy resin 2, 1.04% by mass of curing agent 1, 2.07% by mass of curing agent 2, and 0% of curing accelerator 2. .06% by mass, 51.31% by mass of AA-18 as a filler, 18.66% by mass of AA-3, 7.77% by mass of AA-04, and 0% of KBM-573 as an additive. 01% by mass and 14.2% by mass of CHN as a solvent were mixed to prepare a varnish-like resin composition.
The density of the alumina (AA-04, AA-3, AA-18) is 3.98 g/cm ³ and the density of the resin (mixture of epoxy resin and curing agent) is 1.20 g/cm ³ . The ratio of the filler to the total solid volume was calculated to be 74% by volume.

(Preparation of A stage sheet)
Using a PET film as a support, the resin composition was coated onto the PET film using a table coater (Tester Sangyo Co., Ltd.). The film was dried by heating in a box oven at 130° C. for 6 minutes to obtain an A-stage sheet in which a resin composition layer in an A-stage state was formed on the PET film.

(Preparation of C stage sheet for evaluation)
A copper foil was placed on the dried A-stage sheet, and hot pressurized using a vacuum press (press temperature: 150°C, degree of vacuum: 1 kPa, press pressure: 10 MPa, press time: 1 minute). The resin sheet with copper foil was brought to a B stage state.
The PET film was peeled off from the copper foil-attached resin sheet in the B stage state, and the copper foil was placed on top of it. In this state, vacuum thermocompression bonding was performed using a vacuum press (press temperature: 150° C., degree of vacuum: 1 kPa, press pressure: 10 MPa, press time: 30 minutes). Thereafter, it was heated at 150° C. for 2 hours and at 210° C. for 4 hours under atmospheric pressure conditions to obtain a C-stage sheet with copper foil.

[Comparative example 2]
(Preparation of resin composition)
1.63% by mass of epoxy resin 1, 8.12% by mass of epoxy resin 2, 2.02% by mass of curing agent 1, 3.40% by mass of curing agent 2, and 0% by mass of curing accelerator 2. .12% by mass, 50.28% by mass of AA-18 as a filler, 18.28% by mass of AA-3, 7.61% by mass of AA-04, and 0% of KBM-573 as an additive. 01% by mass and 8% by mass of CHN as a solvent were mixed to prepare a varnish-like resin composition.
The density of the alumina (AA-04, AA-3, AA-18) is 3.98 g/cm ³ and the density of the resin (mixture of epoxy resin and curing agent) is 1.20 g/cm ³ . The ratio of the filler to the total solid volume was calculated to be 60% by volume.

(Preparation of A stage sheet)
An A-stage sheet was produced in the same manner as in Comparative Example 1.
(Preparation of C stage sheet for evaluation)
A C-stage sheet was produced in the same manner as Comparative Example 1 except that the press pressure was changed to 1 MPa.

[evaluation]
(Evaluation of thermal conductivity)
The copper foil of the produced C-stage sheet with copper foil was removed by etching to obtain a C-stage sheet. The obtained C-stage sheet was cut into pieces of 10 mm in length and 10 mm in width to obtain samples. After blackening the sample with graphite spray, the thermal diffusivity was evaluated using the xenon flash method (NETZSCH LFA447 nanoflash). The thermal conductivity in the thickness direction of the C-stage sheet was determined from the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (differential scanning calorimeter; Perkin Elmer DSC Pyris 1). The results are shown in Table 1.

(Measurement of storage modulus)
The copper foil of the produced C-stage sheet with copper foil was removed by etching to obtain a C-stage sheet. The obtained C-stage sheet was cut into pieces of 30 mm in length and 5 mm in width to obtain samples. A tensile test was performed using a dynamic viscoelasticity measurement device (TA Instruments, trade name RSA II) at a frequency of 10 Hz, a heating rate of 5°C/min, and a temperature of 25°C to 300°C. The elastic modulus (storage elastic modulus) at °C was determined. The results are shown in Table 1.

As shown in Table 1, in Comparative Example 1 using an epoxy resin having a mesogenic structure, the cured product of the resin composition had sufficient thermal conductivity, but the storage modulus was high. In Comparative Example 2, in which the amount of filler was reduced compared to Comparative Example 1, the storage modulus was lower than that in Comparative Example 1, but sufficient thermal conductivity was not obtained.
Examples 1 and 2 using acrylic resins containing blocked isocyanate groups achieved both low storage modulus and high thermal conductivity.

102: Cured resin sheet, 104: Heat dissipation base substrate, 106: Metal plate, 108: Semiconductor chip, 110: Solder layer, 112: Mold resin, 114: Sealing material

Claims (12)

Contains a (meth)acrylic resin containing an optionally blocked isocyanate group, a filler, a phenolic curing agent, and a curing accelerator ,
A resin composition in which the content of the (meth)acrylic resin containing an optionally blocked isocyanate group is 1% by mass to 30% by mass. The resin composition according to claim 1, wherein the (meth)acrylic resin contains a blocked isocyanate group, and the deprotection initiation temperature of the blocked isocyanate group is 40°C or higher. The resin composition according to claim 1 or 2, further comprising an epoxy resin. Any one of claims 1 to 3 , wherein the filler contains at least one member selected from the group consisting of alumina, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, magnesium oxide, magnesite, silica, and graphite. The resin composition according to item 1. The resin composition according to any one of claims 1 to 4 , wherein the content of the filler is 30% to 90% by volume. A resin sheet having a resin composition layer containing the resin composition according to any one of claims 1 to 5 . A B-stage sheet having a semi-cured resin composition layer containing a semi-cured product of the resin composition according to any one of claims 1 to 5 . A C-stage sheet having a cured resin composition layer containing a cured product of the resin composition according to any one of claims 1 to 5 . A cured product of the resin composition according to any one of claims 1 to 5 . A resin-coated metal foil comprising a metal foil and a semi-cured resin composition layer containing a semi-cured resin composition according to any one of claims 1 to 5 , disposed on the metal foil. . a metal support, a cured resin composition layer comprising a cured product of the resin composition according to any one of claims 1 to 5 disposed on the metal support, and the cured resin composition layer a metal plate disposed on the metal substrate; The curing of the resin sheet according to claim 6 , further comprising a semiconductor module in which a metal plate, a solder layer, and a semiconductor chip are laminated in this order, a heat dissipation member, and a heat dissipation member disposed between the metal plate and the heat dissipation member of the semiconductor module. A power semiconductor device comprising: