Low dielectric heat dissipation material

Abstract

To provide a composition that combines low dielectric properties and high thermal conductivity, and a cured product thereof. The present invention relates to a method for producing a polymerizable composition comprising: 15 to 70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer; 85 to 30 parts by mass of boron nitride powder that satisfies all of the following (A) to (C) A composition comprising a total of 100 parts by mass. (A) The average particle size of the boron nitride powder is 3 μm or more and 100 μm or less. (B) Crushing strength is 6 MPa or more and 20 MPa or less. (C) The orientation index of the boron nitride powder is 5 or more and 20 or less.

Description

[Technical Field]

[0001] The present invention relates to a composition comprising a specific copolymer and a specific boron nitride powder, and a cured product thereof. [Background technology]

[0002] As Moore's Law approaches its limits due to increasing interconnect density, in addition to the conventional increase in interconnect density within semiconductor devices, there is a demand for higher integration (chiplets) through three-dimensional, 3D packaging and functional integration between component devices. As interconnects within devices become multilayered, miniaturized, and denser, insulating materials for substrates, interposers, and redistribution layers are particularly required to prevent high-frequency signal delays and noise generation. Furthermore, because temperature changes in insulating materials, not just devices, can affect circuit characteristics, efficient removal of heat generated by multilayered, miniaturized, and densely packed devices is required. Furthermore, insulating materials with excellent high-frequency signal transmission and heat dissipation properties are also required for multilayer antenna substrates containing RFICs and high-frequency wiring (antenna feedlines) layered beneath the antenna structure for Massive MIMO (phased array antenna / multilayer substrate for transmitter circuit) for 5G and 6G base stations. Furthermore, in next-generation optical interconnect components (switching integrated circuits for optical transceivers in co-packages), there is a demand for efficient removal of the large amounts of heat generated by switching high-frequency signals in switching integrated circuits (ASICs).

[0003] Fluorine-based resins such as perfluoroethylene have traditionally been used as insulating materials for such high-frequency transmission circuits. While these materials possess low dielectric constants, low dielectric loss, and excellent heat resistance, they present challenges in terms of moldability and film formation, making it difficult to achieve multilayer and high-density wiring, and they also pose problems with adhesion to copper foil. Furthermore, there are issues with the ability to incorporate heat-dissipating fillers to ensure thermal conductivity. Therefore, hydrocarbon-based resins, which inherently possess low dielectric properties, have attracted attention. Patent Document 1 discloses a cured product obtained from a specific coordination polymerization catalyst and consisting of an ethylene-olefin (aromatic vinyl compound)-aromatic polyene copolymer with a specific composition and blend, and a nonpolar vinyl compound. This technology selectively copolymerizes only one of the two vinyl groups in the aromatic polyene (divinylbenzene), preserving the remaining vinyl group. This facilitates the production of crosslinkable hydrocarbon-based copolymer macromonomers bearing aromatic vinyl groups as functional groups, which exhibit high reactivity (crosslinkability). Cured products obtained from compositions of similar olefin-aromatic vinyl compound-aromatic polyene copolymers and auxiliary materials are characterized by low dielectric constants and low dielectric loss tangents, and by selecting the appropriate composition and auxiliary materials, it is possible to impart a wide range of physical properties, from soft to hard (Patent Documents 2 and 3). Furthermore, these copolymers can be filled with relatively large amounts of inorganic filler, and it is said that they can have a variety of properties depending on the type of inorganic filler (Patent Document 4).

[0004] However, the prior art mixture of copolymer and inorganic filler, as described in Patent Document 4, did not adequately resolve the problem of thermal conductivity. Inorganic fillers, such as alumina, silicon nitride, and aluminum nitride, commonly used to impart thermal conductivity, have an extremely high dielectric constant of approximately 10, resulting in a particularly high dielectric constant for cured products obtained using such conventional inorganic fillers. Furthermore, while scaly boron nitride according to prior art is known to have a relatively low dielectric constant and high thermal conductivity, it suffers from the problem of high anisotropy in thermal conductivity and physical properties, making it difficult to achieve high loadings in resin. Specifically, scaly boron nitride crystal particles are highly planar and exhibit high in-plane thermal conductivity. Therefore, simply filling a resin with scaly boron nitride crystal particles and forming them into a sheet by press molding or other methods results in the highly planar particles being oriented laterally, making it impossible to obtain a composite sheet with high thermal conductivity perpendicular to the sheet. Attempting to obtain a structure in which boron nitride particles are oriented perpendicular to the sheet in a thermoplastic resin sheet requires a complex molding process, which is economically disadvantageous (Patent Document 5). Furthermore, for high-frequency packaging applications, the manufacturing process includes heat-resistant processes such as solder reflow, making thermoplastic resins difficult to use due to their insufficient heat resistance. Furthermore, even when agglomerated powder is used, which is made by agglomerating flaky boron nitride powder, the anisotropy is still high, and because the crushing strength is low, the agglomerates may break down during molding, resulting in the risk of anisotropy becoming apparent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-161743 [Patent Document 2] International Publication No. 2021 / 112087 [Patent Document 3] International Publication No. 2022 / 014599 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-280860 [Patent Document 5] Japanese Patent Publication No. 2024-006085 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above background art, therefore, a new method is required that can achieve both a low dielectric loss tangent and high thermal conductivity even in applications for multilayered, miniaturized, and highly dense high-frequency transmission wiring. [Means for solving the problem]

[0007] That is, the present invention can provide the following aspects.

[0008] Aspect 1 15 to 70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer, 85 to 30 parts by mass of boron nitride powder that satisfies all of the following (A) to (C) A composition comprising a total of 100 parts by mass. (A) The average particle size of the boron nitride powder is 3 μm or more and 100 μm or less. (B) Crushing strength is 6 MPa or more and 20 MPa or less. (C) The orientation index of the boron nitride powder is 5 or more and 20 or less.

[0009] Aspect 2 2. The composition of embodiment 1, wherein the boron nitride powder has a purity of 95% by weight or greater.

[0010] Aspect 3 The composition according to aspect 1 or 2, wherein the olefin-aromatic vinyl compound-aromatic polyene copolymer satisfies all of the following (1) to (5): (1) The number average molecular weight of the copolymer is 500 or more and 30,000 or less. (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of aromatic vinyl compound monomer units is 0.1 to 70% by mass. (3) The olefin monomer unit is one or more selected from α-olefin monomer units having 2 to 30 carbon atoms and cyclic olefin monomer units having 7 to 30 carbon atoms, and the content thereof is 5% by mass to 95% by mass. (4) The aromatic polyene monomer is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 to 30 per number average molecular weight. (5) The total amount of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass.

[0011] Aspect 4 A composition according to any one of Aspects 1 to 3, wherein the olefin monomer units constituting the olefin-aromatic vinyl compound-aromatic polyene copolymer include at least a cyclic olefin monomer unit.

[0012] Aspect 5 A composition according to any one of Aspects 1 to 4, wherein a cured product obtained by curing the olefin-aromatic vinyl compound-aromatic polyene copolymer alone has a dielectric constant of less than 2.5 and a dielectric loss tangent of less than 0.0008, as measured at 40 GHz and 25°C.

[0013] Aspect 6 A cured product of the composition according to any one of aspects 1 to 5.

[0014] Aspect 7 7. The cured product according to embodiment 6, having a dielectric constant of 3.0 or more and 5.0 or less, and a dielectric loss tangent of 0.0002 or more and 0.0030 or less.

[0015] Aspect 8 8. The cured product according to claim 6 or 7, having a thermal conductivity of 3 W / (m·K) or more.

[0016] Aspect 9 The cured product according to any one of aspects 6 to 8, which is in the form of a sheet.

[0017] Aspect 10 A high-frequency transmission circuit comprising the cured product according to any one of aspects 6 to 9.

[0018] Aspect 11 A single-layer or multi-layer CCL (copper clad laminate) substrate, a single-layer or multi-layer FCCL (flexible copper clad laminate) substrate, an interlayer insulating material, or an antenna, comprising the cured product according to any one of aspects 6 to 9.

[0019] Aspect 12 A three-dimensional highly integrated circuit packaging package or chiplet comprising the cured product according to any one of embodiments 6 to 9. [Effects of the Invention]

[0020] The present invention can provide a composition having a low dielectric loss tangent and high thermal conductivity, which can be used as an insulating material suitable for use in multilayered, finely divided, and highly dense high-frequency transmission wiring applications. DETAILED DESCRIPTION OF THE INVENTION

[0021] In the present specification, which will be described in further detail below, the olefin-aromatic vinyl compound-aromatic polyene copolymer may be simply referred to as the copolymer of the present invention or simply as the copolymer. Furthermore, boron nitride powder satisfying the conditions (A) to (C) may be simply referred to as a specific boron nitride powder. Numerical ranges in the present specification include the upper and lower limits unless otherwise specified. The term "sheet" in the present specification also encompasses the concept of a film. Furthermore, the term "film" in the present specification also has the same meaning as "sheet." Furthermore, the term "film" in the present specification also encompasses the concept of a sheet. The term "cured state" in the present specification is defined as a state in which the gel fraction (gel content) of the olefin-aromatic vinyl compound-aromatic polyene copolymer is 80% by mass or more, more specifically 90% by mass or more, and most specifically 95% by mass or more. The gel content is a value obtained by measurement in accordance with JIS K6796:1998 or measurement in accordance with ASTM D2765-84, which corresponds to ISO10147:1994, which corresponds to JIS.

[0022] In one embodiment of the present invention, a composition containing an olefin-aromatic vinyl compound-aromatic polyene copolymer and a specific boron nitride is provided, and in another embodiment, a three-dimensional highly integrated circuit packaging package or chiplet is provided that includes an insulating material made of a cured form of the composition.

[0023] The composition may contain an olefin-aromatic vinyl compound-aromatic polyene copolymer and a boron nitride powder that satisfies all of the following (A) to (C) in a mass ratio ranging from 15:85 to 70:30, preferably from 20:80 to 50:50. (A) The average particle size of the boron nitride powder is 3 μm or more and 100 μm or less, preferably 8 μm or more and 50 μm or less, and most preferably 20 μm or more and 40 μm or less. (B) The lower limit of the crushing strength is 6 MPa or more, preferably 8 MPa or more, and more preferably 10 MPa or more and 20 MPa or less. (C) The orientation index of the boron nitride powder is 5 or more and 20 or less, preferably 5 or more and 15 or less. A boron nitride powder that satisfies all of the conditions (A) to (C) is a boron nitride powder containing agglomerated particles formed by tightly agglomerating primary particles of hexagonal boron nitride. In this specification, such boron nitride powder is also referred to as "lump boron nitride" to distinguish it from the scaly boron nitride powder of the prior art. Unless otherwise specified, the term "boron nitride powder" used in this specification refers to the "lump boron nitride" described above. In other words, the composition contains 15 to 70 parts by mass of the copolymer and 85 to 30 parts by mass of the bulk boron nitride powder, totaling 100 parts by mass.

[0024] The average particle size of boron nitride powder is the particle size (median size, d50) at which the cumulative value of the cumulative particle size distribution is 50%. The average particle size in this specification is measured using a laser diffraction scattering particle size distribution analyzer in accordance with ISO13320:2009. Specifically, it is measured by the method described in the Examples of this specification. The laser diffraction scattering particle size distribution analyzer may be, for example, the "LS-13 320" (product name) manufactured by Beckman Coulter, Inc.

[0025] The specific surface area of ​​boron nitride powder is 0.8 to 20.0 m 2 / g is preferred. When the specific surface area is within the above range, a filler with excellent packing properties and heat dissipation properties can be provided. The specific surface area in this specification refers to a value measured using a specific surface area measuring device in accordance with the description of JIS Z8830:2013 "Method for measuring the specific surface area of ​​powders (solids) by gas adsorption," and is a value calculated by applying the BET single-point method using nitrogen gas. Specifically, it is measured by the method described in the examples of this specification.

[0026] The term "crushing strength" as used herein refers to a value measured in accordance with JIS R1639-5:2007, "Fine Ceramics - Measurement Methods for Granule Properties - Part 5: Single Granule Crushing Strength." The term "orientation index" as used herein refers to the ratio of the peak intensity of the (002) plane of boron nitride to the peak intensity of the (100) plane as measured using an X-ray diffractometer, and can be calculated as [I(002) / I(100)]. An orientation index of 5 to 20, preferably 5 to 15, for boron nitride powder indicates that boron nitride primary particles are inherently tabular and highly oriented as they are. However, a value within this range indicates that multiple boron nitride primary particles have aggregated in a disordered manner, forming clumps and bonding together, reducing the orientation. The bonding strength of this clumped structure is expressed as the preferred value for the crushing strength. Specifically, the lower limit of the crushing strength may be 6 MPa or more, preferably 8 MPa or more, more preferably 10 MPa or more, and even more preferably 20 MPa or less.

[0027] More preferably, the purity of the boron nitride powder is 95% by mass or more. Specifically, this purity is measured by the method described in the examples of this specification.

[0028] The above methods for producing boron nitride powder are described in WO 2022 / 071225 and WO 2020 / 004600. Typically, these methods use a specific type of B4C as a raw material, synthesize B4CN4 through pressurized nitriding, decarburize by heating in the atmosphere, add boric acid, etc., decarburize and crystallize in a crystallization furnace, and then crush and sieve the resulting product.

[0029] The olefin-aromatic vinyl compound-aromatic polyene copolymer used in the present invention may preferably satisfy all of the following (1) to (5). (1) The number average molecular weight of the copolymer is 500 or more and 30,000 or less. (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer is 0.1 to 70% by mass. (3) The olefin monomer unit is one or more selected from α-olefin monomer units having 2 to 30 carbon atoms and cyclic olefin monomer units having 7 to 30 carbon atoms, and the content thereof is 5% by mass to 95% by mass. (4) The aromatic polyene monomer is one or more polyenes selected from polyenes having 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units is 2 to 30 per number average molecular weight. (5) The total amount of the olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass. The olefin-aromatic vinyl compound-aromatic polyene copolymer is obtained by copolymerizing the olefin, aromatic vinyl compound, and aromatic polyene monomers.

[0030] Here, the olefin monomer (referring to a monomer from which the olefin monomer units in the copolymer are derived, but in this specification, the terms "monomer" and "monomer unit" may be used interchangeably depending on the context; the same applies to similar terms hereinafter) refers to a single or multiple monomers selected from α-olefin monomers having 2 to 20 carbon atoms and cyclic olefin monomers having 7 to 30 carbon atoms. Examples of α-olefin monomers having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 3,5,5-trimethyl-1-hexene. A combination of ethylene and an α-olefin other than ethylene is preferred, and ethylene is most preferred. The content of the α-olefin monomer units in the copolymer is optional, but is preferably 0 to 70% by mass, more preferably more than 0 to 60% by mass, and even more preferably 1 to 60% by mass. The higher the α-olefin monomer unit content (for example, 5% by mass or more), the easier it is to avoid the copolymer and its cured product from becoming brittle, which is preferable.

[0031] As used herein, the term "cyclic olefin monomer" refers to a cyclic olefin having 7 to 30 carbon atoms. Cyclic olefins having 7 to 30 carbon atoms are cyclic olefins having one or more alicyclic structures in the molecule and a polymerizable vinyl group, vinylene group, or vinylidene group. Preferred cyclic olefins are cyclic olefins having a hydrocarbon ring structure without heteroatoms, and more preferred are cyclic olefins having an unsaturated hydrocarbon ring. These cyclic olefins have the distinct advantages of low dielectric properties and high glass transition temperatures, while being easily prepared using inexpensive raw materials and simple processes compared to conventional engineering plastics.

[0032] Examples of such cyclic olefins include norbornenes and acenaphthylene. Norbornenes are monomers selected from norbornene and substituted norbornenes. Norbornene can be synthesized, for example, by the Diels-Alder reaction of ethylene and cyclopentadiene. Substituted norbornenes are substituted norbornenes having a polymerizable vinyl group, vinylene group, or vinylidene group in the molecule, such as dimethanooctahydronaphthalene (DMON) and trimethanododecahydroanthracene (TMDA). These are also Diels-Alder reaction products of norbornenes and cyclopentadiene. These substituted norbornenes are specifically described in, for example, WO 2006 / 118261. In the present invention, more preferred cyclic olefins have a larger number of ring structures and a higher molecular weight, such as dimethanooctahydronaphthalene (DMON) and trimethanododecahydroanthracene (TMDA). Copolymerization of such cyclic olefins allows the production of copolymers with higher glass transition temperatures (Tg) at lower mol% content of the monomer units. This allows the mol% content of other monomer units to be increased while maintaining the high glass transition temperature of the copolymer. Increasing the mol% content of aromatic vinyl compound monomer units as other monomer units enhances the aromatic properties of the copolymer as a whole, which is preferable because it improves the compatibility of the copolymer with other raw materials and resins. These high molecular weight cyclic olefins may be used alone or in a mixture with norbornene or the like for copolymerization.

[0033] In particular, the above-mentioned DMON and TMDA may be obtained as a mixture with norbornene when produced by Diels-Alder reaction, and by using the mixture as is for polymerization, it is possible to reduce production costs. Furthermore, in the present invention, more preferred cyclic olefins are norbornenes having aromatic substituents, such as phenylnorbornene (5-phenylbicyclo[2.2.1]hept-2-ene), a Diels-Alder reaction product of cyclopentadiene and styrene, indanylnorbornene (1,4-methano-1,9a,4,4a-tetrahydrofluorene), a Diels-Alder reaction product of cyclopentadiene and indene, and methylphenylnorbornene (MPNB, 5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene), a Diels-Alder reaction product of cyclopentadiene and α-methylstyrene. When copolymerized, norbornenes with such aromatic substituents can impart a higher glass transition temperature (Tg) to the resulting copolymer. Furthermore, because of their aromaticity, they exhibit high compatibility with other aromatic raw materials (crosslinkable soft resins and flame retardants). Furthermore, the use of methylphenylnorbornene (5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene) is preferred because it improves the thermal oxidation resistance of the resulting copolymer, as described in JP-A-2005-239975. Norbornenes with these aromatic substituents are specifically described, for example, in JP-A-11-504669 and JP-A-2005-239975.

[0034] The content of cyclic olefin monomer units contained in the copolymer is arbitrary. However, when a high glass transition temperature (Tg) of the copolymer is desired, the optimal content of cyclic olefin monomer units contained in the copolymer varies depending on the type of cyclic olefin. For example, it is 50% by mass to 95% by mass, preferably 50% by mass to 95% by mass, more preferably 70% by mass to 95% by mass, and most preferably 80% by mass to 95% by mass. The higher the content of cyclic olefin monomer units, the higher the Tg of the copolymer. The optimal content of cyclic olefin monomer units contained in the copolymer may be less than 90% by mass from the viewpoint of imparting a certain degree of toughness to the copolymer. A content within these ranges facilitates the achievement of a desirable high glass transition temperature of the copolymer. The glass transition temperature of the copolymer is preferably 100°C to 350°C, more preferably 130°C to 300°C, and most preferably 180°C to 300°C. On the other hand, when the content of the cyclic olefin monomer units is in the range of 10% by mass or more but less than 50% by mass, a copolymer with a relatively low Tg is obtained. In particular, for copolymers that are soft at room temperature, the content of the cyclic olefin monomer units is in the range of 10% by mass or more but less than 40% by mass. Those skilled in the art can appropriately adjust the type and content of the cyclic olefin used to achieve this preferred glass transition temperature. Furthermore, the higher the content of the cyclic olefin monomer units in the copolymer, the more improved the low dielectric properties of the copolymer itself, its composition, or its cured product. Specifically, the higher the content of the cyclic olefin monomer units in the copolymer, the lower the dielectric loss tangent of the copolymer itself, its composition, or its cured product, which is preferable.

[0035] In a preferred embodiment, the cyclic olefin monomer units contained in the copolymer may include monomer units derived from one or more selected from the group consisting of norbornene, methylphenylnorbornene, substituted norbornenes other than methylphenylnorbornene, and dimethanooctahydronaphthalene, and more preferably, may include monomer units derived from one or more selected from the group consisting of norbornene, methylphenylnorbornene, and dimethanooctahydronaphthalene.

[0036] The aromatic vinyl compound monomer is an aromatic vinyl compound having from 8 to 20 carbon atoms, such as styrene, paramethylstyrene, ethylvinylbenzene, paraisobutylstyrene, various vinylnaphthalenes, and various vinylanthracenes. The aromatic vinyl compound monomer contains one vinyl group within the monomer. The monomer units derived from the aromatic vinyl compound may be contained in the copolymer as a result of copolymerization of aromatic vinyl compound components contained as impurities in the aromatic polyene used in polymerization. The content of the aromatic vinyl compound monomer units contained in the copolymer is optional, but is preferably from 0.1 to 70% by mass, more preferably from 1 to 60% by mass.

[0037] When the content of aromatic vinyl compound monomer units is 10% by mass or more, the aromaticity of the copolymer can be improved, which improves compatibility with other resin materials, flame retardants, and fillers, suppresses bleed-out of flame retardants, and facilitates high filler loading, which is preferable. As described above, the glass transition temperature and aromaticity of the copolymer can be adjusted by the content of cyclic olefin monomer units and the content of aromatic vinyl compound monomer units of the copolymer.

[0038] The aromatic polyene monomer is a polyene having 5 to 20 carbon atoms and containing multiple vinyl and / or vinylene groups in its molecule, preferably a polyene having 8 to 20 carbon atoms. The aromatic polyene monomer is preferably a polyene having 8 to 20 carbon atoms and containing multiple vinyl groups in its molecule, more preferably a compound having an aromatic vinyl structure, such as ortho-, meta-, or para-divinylbenzenes or mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, or p-3-butenylstyrene, and consisting essentially of carbon and hydrogen without containing oxygen, nitrogen, or halogen. Bifunctional aromatic vinyl compounds, such as 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE), described in JP 2004-087639 A, can also be used. Among these, ortho-, meta-, or para-divinylbenzenes or mixtures thereof are preferred, and a mixture of meta- and para-divinylbenzene is most preferred. In this specification, these divinylbenzenes are referred to as divinylbenzenes. When a divinylbenzene is used as the aromatic polyene, the vinyl group contained in the divinylbenzene unit is preferred because it has high crosslinking efficiency during curing treatment and facilitates curing.

[0039] The number-average molecular weight of the copolymer is preferably 500 to 50,000, more preferably 500 to 30,000 or less than 30,000, even more preferably 500 to 15,000 or less than 15,000, and even more preferably 500 to 12,000 or less than 12,000. A number-average molecular weight of 500 or more improves the mechanical properties of the composition in the uncured state and provides appropriate adhesion, thereby facilitating molding and processing as a thermoplastic resin. A number-average molecular weight of 30,000 or less improves molding processability. A number-average molecular weight of 30,000 or less is particularly advantageous because it allows the viscosity of a varnish containing the copolymer to be kept below a certain value. A varnish viscosity below a certain value improves workability and facilitates impregnation of glass fibers and the like with the varnish, improving embedding properties in semiconductor devices with uneven surfaces.

[0040] In the copolymer, the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units may be 2 to 30, preferably 3 to 20, per number-average molecular weight. The content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer units may be less than 30, preferably less than 20, per number-average molecular weight. The content of vinyl groups and / or vinylene groups may be collectively referred to as the "vinyl group content" below. Since vinyl groups are superior to vinylene groups in terms of crosslinking efficiency, in the present invention, the content of vinyl groups (excluding vinylene groups in this case) derived from the aromatic polyene monomer units is preferably 2 to 30, preferably 3 to 20, per number-average molecular weight. A vinyl group content of 2 or more results in high crosslinking efficiency and a cured product with sufficient crosslink density. Increasing the vinyl group content facilitates improving the mechanical properties of the final cured product at room temperature and high temperature. The vinyl group content derived from aromatic polyene monomer units (divinylbenzene monomer units) per number average molecular weight in the copolymer is calculated by the number average molecular weight (Mn) calculated in terms of standard polystyrene obtained by a GPC (gel permeation chromatography) method known to those skilled in the art, and 1 H-NMR measurement and / or quantitative mode 13 The composition can be determined by comparing the composition determined by C-NMR measurement with the vinyl group content derived from aromatic polyene monomer units. Such a method is obvious and well known to those skilled in the art. For example, the composition of an ethylene-norbornene-styrene-ethylvinylbenzene-divinylbenzene copolymer, which is a representative example of the present copolymer, can also be determined by the following method. 1 H-NMR measurement and quantitative mode 13 C-NMR measurement was performed, and the NMR peak area intensity ( 1 H, 13 C) to determine the proportion (a) of divinylbenzene units contained, and the strength ( 1 H, 13C) to determine the proportion (b) of ethylvinylbenzene units contained in small amounts as impurities in divinylbenzene, and calculate the area intensity ( 1 H, 13 The proportion of styrene units (c) is calculated by subtracting the contributions of (a) and (b) from (c), and finally the area intensity of the aliphatic hydrocarbon region ( 1 H, 13 The ratio (d) of olefin units (total of ethylene and norbornene units) is calculated by subtracting the contributions of (a), (b), and (c) from (c). Separately, the area intensity ratio ( 13 From C), the abundance ratio (e) of ethylene and norbornene units can be calculated, and by combining (a), (b), (c), (d), and (e), the contents of ethylene, norbornene, styrene, divinylbenzene, and ethylvinylbenzene can be calculated.

[0041] The content of aromatic polyene monomer units in the present copolymer is arbitrary, but is preferably less than 30% by mass, more preferably less than 18% by mass, and most preferably less than 15% by mass. At such a content, the number of crosslinking groups is appropriately suppressed, and the effect of improving the stability during copolymer production and curing is obtained.

[0042] Specific examples of the α-olefin-aromatic vinyl compound-aromatic polyene copolymer as one embodiment of the present copolymer include an ethylene-styrene-divinylbenzene copolymer, an ethylene-ethylvinylbenzene-divinylbenzene copolymer, an ethylene-propylene-styrene-divinylbenzene copolymer, an ethylene-1-octene-styrene-divinylbenzene copolymer, and a propylene-styrene-divinylbenzene copolymer. Specific examples of suitable α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymers include one or more members selected from the group consisting of ethylene-norbornene-styrene-divinylbenzene copolymer, propylene-norbornene-styrene-divinylbenzene copolymer, 1-hexene-norbornene-styrene-divinylbenzene copolymer, 1-octene-norbornene-styrene-divinylbenzene copolymer, ethylene-norbornene-ethylvinylbenzene-divinylbenzene copolymer, propylene-styrene-norbornene-divinylbenzene copolymer, 1-hexene-styrene-styrene-norbornene-divinylbenzene copolymer, and 1-octene-norbornene-styrene-divinylbenzene copolymer. Further, copolymers in which the above-mentioned norbornene is replaced with dimethanooctahydronaphthalene (DMON), trimethanododecahydroanthracene (TMDA), phenylnorbornene (5-phenylbicyclo[2.2.1]hept-2-ene), or methylphenylnorbornene (5-methyl-5-phenylbicyclo[2.2.1]hept-2-ene) are also suitable examples of copolymers of the present invention.

[0043] The olefin-aromatic vinyl compound-aromatic polyene copolymer preferably used in the composition of the present invention is a copolymer in which the olefin monomer units contain at least cyclic olefin monomer units. By including cyclic olefin monomer units as part of the olefin monomer units, the dielectric dissipation factor of the copolymer itself can be lowered compared to copolymers containing no cyclic olefin. For example, when the copolymer is cured using the minimum necessary amount of curing agent, the dielectric dissipation factor measured at 40 GHz is lower than that of copolymers containing no cyclic olefin monomer units. Therefore, this is preferred for lowering the dielectric dissipation factor of compositions using copolymers containing cyclic olefin monomer units and their cured products. Furthermore, the inclusion of cyclic olefin monomer units in the copolymer, or an increase in their content, tends to increase the thermal conductivity when compared to cured products of compositions containing boron nitride prepared using the same method and at the same blend ratio. Furthermore, increasing the cyclic olefin monomer unit content increases the glass transition temperature of the copolymer, thereby hardening the copolymer and its cured product. Considering that insulating materials for CCL, three-dimensional integrated circuit packaging, or chiplets, which are preferred applications of the present invention, are hard and require a low linear expansion coefficient close to that of wiring metals such as silicon and copper, a higher content of cyclic olefin monomer units as described above is preferred. Furthermore, if a portion of the olefin monomer units in the olefin-aromatic vinyl compound-aromatic polyene copolymer contains cyclic olefin monomer units, the higher the content of these cyclic olefin monomer units, i.e., the higher the glass transition temperature of the copolymer, the higher the thermal conductivity of the cured product of the composition tends to be.

[0044] The olefin-aromatic vinyl compound-aromatic polyene copolymer preferably used in the composition of the present invention is an olefin-aromatic vinyl compound-aromatic polyene copolymer that, when cured alone, produces a cured product that exhibits a dielectric constant of less than 2.5 and a dielectric dissipation factor of less than 0.0008, preferably less than 0.0006, measured at 40 GHz and 25°C. Preferred olefin-aromatic vinyl compound-aromatic polyene copolymers that satisfy these requirements are copolymers containing a cyclic olefin component in the olefin component. In this specification, "curing alone" is defined as curing the olefin-aromatic vinyl compound-aromatic polyene copolymer using the minimum necessary amount, i.e., 1% by mass or less of an azo-based curing agent or a curing agent consisting of carbon and hydrogen atoms, based on the mass of the copolymer, under conditions appropriate for the curing agent.

[0045] In an embodiment of the α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer, the content of α-olefin monomer units may be 0% by mass (i.e., no α-olefin monomer units are included). Such copolymers are also referred to herein as "cyclic olefin-aromatic vinyl compound-aromatic polyene copolymers." The composition of the present invention may contain multiple olefin-aromatic vinyl compound-aromatic polyene copolymers with different compositions and molecular weights.

[0046] <Composition containing copolymer and specific boron nitride powder> Although the composition containing the copolymer of the present invention and a specific boron nitride powder can be cured by itself, the copolymer of the present invention may be combined with other materials to form a composition, which can then be cured. Here, the other materials include the following "resin component," "curing agent," "monomer," "solvent," "other filler," "other additives," etc.

[0047] <Resin component> Any resin component can be used as long as it does not impair the effects of the present invention. Preferably, one or more resins selected from hydrocarbon-based elastomers, polyether-based resins, aromatic polyene-based resins, and olefin-aromatic vinyl compound-aromatic polyene copolymers containing no cyclic olefin monomer units are used. Among these, hydrocarbon-based elastomers and olefin-aromatic vinyl compound-aromatic polyene copolymers containing no cyclic olefins are more preferred. Among hydrocarbon-based elastomers, conjugated diene polymers are preferred. Among conjugated diene polymers, 1,2-polybutadiene is preferred. The total amount of resin components is preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer. Adding too many of these resin components may result in a high dielectric constant and dielectric loss tangent of the final cured product. Furthermore, when a resin component is added to the olefin-aromatic vinyl compound-aromatic polyene copolymer, the ratio of the total mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer and the resin component to the mass of the specific boron nitride powder is in the range of 15:85 to 70:30, and preferably in the range of 20:80 to 50:50.

[0048] <Hydrocarbon elastomer> The hydrocarbon-based elastomer suitable for use in the composition of the present invention may have a number-average molecular weight of 20,000 or more, preferably 30,000 or more. Examples of hydrocarbon-based elastomers include single or multiple elastomers selected from ethylene-based or propylene-based elastomers, conjugated diene polymers, block or random copolymers of aromatic vinyl compounds and conjugated dienes, and hydrogenated products thereof. Examples of ethylene-based elastomers include ethylene-α-olefin copolymers such as ethylene-octene copolymers and ethylene-1-hexene copolymers, EPR, and EPDM. Examples of propylene-based elastomers include atactic polypropylene, low stereoregular polypropylene, and propylene-α-olefin copolymers such as propylene-1-butene copolymer. These hydrocarbon-based elastomers may be modified, for example, by introducing functional groups using maleic anhydride or other compounds.

[0049] <Conjugated diene polymer> Examples of conjugated diene polymers include polybutadiene and 1,2-polybutadiene. Examples of aromatic vinyl compound-conjugated diene block or random copolymers and their hydrogenated products (hydrogenated products) include SBS, SIS, SEBS, SEPS, SEEPS, and SEEBS. Suitable 1,2-polybutadiene is available, for example, as a product from JSR Corporation, and also from Nippon Soda Co., Ltd. under the product names of liquid polybutadiene: B-1000, 2000, and 3000. Another suitable copolymer containing a 1,2-polybutadiene structure is "Ricon 100" from TOTAL CRAY VALLEY. These conjugated diene polymers and their hydrogenated products may be modified, for example, by introducing functional groups with maleic anhydride or other compounds. Among conjugated diene polymers, conjugated diene copolymers are preferred. Among these conjugated diene copolymers, hydrogenated block copolymers such as SEBS, SEPS, SEEPS, and SEEBS are useful as compatibilizers for the copolymer of the present invention and other resin components. These are available from Asahi Kasei under the trade names Tuftec or SOE-SS, from Kuraray Co., Ltd. under the trade name Septon, and from KRATON under the trade name Kraton.

[0050] <Polyether resin> Examples of polyether-based resins include polyphenylene ether and polyether. Polyphenylene ethers having functional groups are preferably those in which the molecular terminals are modified with functional groups. Furthermore, when added for the purpose of curing the composition of the present invention, it is preferable that the polyphenylene ether has multiple functional groups in one molecule. For example, modified polyphenylene ether is preferable. Examples of functional groups include radically polymerizable functional groups and epoxy groups, and radically polymerizable functional groups are preferred. The radically polymerizable functional group is preferably a vinyl group. As the vinyl group, one or more of the group consisting of an allyl group, a (meth)acryloyl group, and an aromatic vinyl group are preferred, and one or more of the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferred, with an aromatic vinyl group being the most preferred. In other words, in the composition of the present invention, a bifunctional polyphenylene ether in which both molecular chain terminals are modified with radically polymerizable functional groups is particularly preferred. Examples of such polyphenylene ethers include Noryl (trademark) SA9000 manufactured by SABIC (modified polyphenylene ether having methacryloyl groups at both ends, number average molecular weight 2200) and bifunctional polyphenylene ether oligomer manufactured by Mitsubishi Gas Chemical Company, Inc. (OPE-2St, modified polyphenylene ether having vinylbenzyl groups at both ends, number average molecular weight 1200). Also usable are allylated PPE manufactured by Asahi Kasei Corporation and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation. Of these, the bifunctional polyphenylene ether oligomer (OPE-2St) manufactured by Mitsubishi Gas Chemical Company, Inc. and aromatic polyethers (ELPAC HC-F series) manufactured by JSR Corporation are preferred.

[0051] <Aromatic polyene resin> The aromatic polyene resin includes divinylbenzene-based reactive hyperbranched copolymers (PDV or ODV) manufactured by Nippon Steel Chemical & Material Co., Ltd. Such copolymers are described, for example, in the literature "Synthesis of Polyfunctional Aromatic Vinyl Copolymers and Development of New IPN-Type Low Dielectric Loss Materials Using Them" (Kawabe Masanao et al., Journal of the Japan Institute of Electronics Packaging, p. 125, Vol. 12, No. 2 (2009)). The aromatic polyene resin is a resin (copolymer) substantially composed of aromatic polyene monomer units and aromatic monovinyl compound monomer units, and more preferably, the aromatic polyene resin does not contain olefin monomer units. The aromatic polyene resin is preferably a resin obtained by cationic polymerization or anionic polymerization.

[0052] <Curing agent> The curing agent that may be contained in the composition may be a known curing agent that can be used for the polymerization or curing of conventional aromatic polyenes and aromatic vinyl compounds. Examples of such curing agents include radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators, but radical polymerization initiators are preferred. Organic peroxides, azo polymerization initiators, etc. are preferred, and can be freely selected depending on the application and conditions. A catalog listing organic peroxides can be found on the NOF Corporation website, for example. https: / / www.nof.co.jp / product-search / family / 1020001 The following information can be downloaded from the website. Organic peroxides are also listed in catalogs from Fujifilm Wako Pure Chemical Industries, Ltd. and Tokyo Chemical Industry Co., Ltd. The curing agents used in the present invention are available from these companies. Furthermore, hydrocarbon-based radical polymerization initiators, i.e., those composed only of carbon and hydrogen atoms and containing no oxygen or nitrogen atoms in their structure, such as 2,3-dimethyl-2,3-diphenylbutane, can also be used. Producing a cured product using such hydrocarbon-based radical polymerization initiators can yield cured products with lower dielectric constants and dielectric dissipation factors, thereby further improving the low dielectric properties of the cured product. Known photopolymerization initiators that utilize light, ultraviolet light, or radiation can also be used as curing agents. Examples of curing agents that use photopolymerization initiators include photoradical polymerization initiators, photocationic polymerization initiators, and photoanionic polymerization initiators. Such photopolymerization initiators are available, for example, from Tokyo Chemical Industry Co., Ltd. Furthermore, curing using radiation or electron beams themselves is also possible. Crosslinking and curing by thermal polymerization of the raw materials contained in the product without the use of a curing agent is also possible.

[0053] There are no particular restrictions on the amount of curing agent used, but generally, an amount of 0.01 to 10 parts by mass per 100 parts by mass of the composition (preferably excluding the curing agent and solvent) is preferred. When using a curing agent such as a peroxide or azo-based polymerization initiator, the curing process should be carried out at an appropriate temperature and time, taking into account its half-life. In this case, the conditions can be determined based on the curing agent, but a temperature range of approximately 50°C to 250°C is generally appropriate.

[0054] <Monomer> The amount of monomer that may be contained in the composition of the present invention is optional, but is preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, per 100 parts by mass of the copolymer. When a monomer component is added to the olefin-aromatic vinyl compound-aromatic polyene copolymer, the ratio of the total mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer and the monomer component to the mass of the specific boron nitride powder is in the range of 15:85 to 70:30, preferably 20:80 to 50:50. The composition may be substantially monomer-free. Monomers that can be suitably used in the composition of the present invention preferably have a molecular weight of less than 1,000, more preferably less than 500. Monomers that can be suitably used in the composition of the present invention include the aromatic vinyl compound monomers, the aromatic polyene monomers, the aromatic vinylene monomers described below, and / or the polar monomers described below. The monomer is preferably a monomer that can be polymerized with a radical polymerization initiator, and more preferably one or more of the group consisting of aromatic vinyl compounds and aromatic polyenes. In addition, BVPE (1,2-bis(vinylphenyl)ethane) described in JP-A-2003-212941 can also be suitably used.

[0055] <Aromatic vinylene monomer> The aromatic vinylene monomer that may be included in the present invention refers to a compound having both a single aromatic ring or multiple condensed aromatic rings having 9 to 30 carbon atoms and a vinylene group. Examples of such aromatic vinylene compounds include indenes, beta-substituted styrenes, acenaphthylenes, etc. Examples of indenes include indene, various alkyl-substituted indenes, and phenyl-substituted indenes. Examples of beta-substituted styrenes include beta-alkyl-substituted styrenes such as beta-methylstyrene, and phenyl-substituted styrenes. Examples of acenaphthylenes include acenaphthylene, various alkyl-substituted acenaphthylenes, and various phenyl-substituted acenaphthylenes. As the aromatic vinylene compound, the above-exemplified compounds may be used alone or in combination of two or more. From the viewpoints of industrial availability and radical polymerizability, acenaphthylene is the most preferred aromatic vinylene compound.

[0056] <Polar monomer> To impart adhesion to other materials required for insulating materials, a relatively small amount of polar monomer can be used, for example, 10 parts by mass or less per 100 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer. Adding more than this amount may result in the dielectric constant and dielectric dissipation factor of the final cured product being higher than desired. Examples of the polar monomer include various maleimides, bismaleimides, maleic anhydride, glycidyl (meth)acrylate, triallyl isocyanurate, tri(meth)acrylic isocyanurate, and trimethylolpropane tri(meth)acrylate. Maleimides and bismaleimides that can be used in the present invention are described, for example, in International Publication No. 2016 / 114287 and are available commercially, for example, from Daiwa Kasei Co., Ltd. These maleimide group-containing compounds may be used as polyaminobismaleimide compounds from the viewpoints of solubility in organic solvents, high-frequency characteristics, high adhesion to conductors, and prepreg moldability. Polyaminobismaleimide compounds can be obtained, for example, by subjecting a compound having two maleimide groups at its terminals to a Michael addition reaction with an aromatic diamine compound having two primary amino groups in the molecule. To achieve high crosslinking efficiency with a small amount of addition, it is preferable to use a polar monomer having two or more multifunctional groups, such as bismaleimides, triallyl isocyanurate (TAIC), and trimethylolpropane tri(meth)acrylate.

[0057] <Solvent> An appropriate solvent may be added to the composition of the present invention as needed. The solvent is used to adjust the viscosity and fluidity of the composition. Volatile solvents are preferred, such as cyclohexane, toluene, ethylbenzene, acetone, and isopropanol. The solvent is used to adjust the viscosity and fluidity of the composition as a varnish. A solvent with a high boiling point at atmospheric pressure, i.e., low volatility, results in a uniform thickness of the applied film; therefore, a solvent with a boiling point above a certain level is preferred. A preferred boiling point is 100°C or higher, more preferably 130°C to 300°C, at atmospheric pressure. Solvents suitable for such varnishes include cyclohexane, toluene, xylene, mesitylene, tetralin, acetone, ethylbenzene, limonene, mixed alkanes, mixed aromatic solvents, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether. In particular, the amount of solvent used is preferably in the range of 10 to 2000 parts by mass, more preferably 5 to 500 parts by mass, and even more preferably 10 to 300 parts by mass, per 100 parts by mass of the composition of the present invention. The solvent is generally substantially removed from the composition by drying or the like before curing the composition.

[0058] <Another filler> If necessary, inorganic fillers other than the above-mentioned boron nitride or organic fillers may be added. Known inorganic fillers, such as fused silica and spherical alumina, can be used as the inorganic filler, and are added for the purposes of controlling the thermal expansion coefficient, controlling thermal conductivity, reducing cost, etc., and the amount added may be 100 parts by mass or less, preferably 50 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the specific boron nitride powder used in the present invention. From the viewpoint of low dielectric properties, adding and blending a filler increases the dielectric constant, so it is preferable to add a small amount.

[0059] Alternatively, organic fillers such as high-molecular-weight polyethylene, ultra-high-molecular-weight polyethylene, polystyrene, styrene-divinylbenzene copolymer, or fluorine-based resins can be used instead of inorganic fillers. Fluorine-based resins include known fluorine-containing resins such as PTFE (polytetrafluoroethylene) and PFA (perfluoroalkoxyalkane). An example of such a resin is Fluon+® EA-2000 from AGC. When the melting point or glass transition temperature of the organic filler is lower than the solder reflow temperature of 290°C, it is preferable for the organic filler itself to be crosslinked from the standpoint of heat resistance, and it is preferable for it to be incorporated in the form of fine particles or powder. These organic fillers can also suppress increases in dielectric constant and dielectric loss tangent. The amount of organic filler added is 100 parts by mass or less, preferably 50 parts by mass or less, per 100 parts by mass of the specific boron nitride powder used in the present invention. Adding more organic filler than this amount may result in the thermal conductivity of the final cured product being lower than desired. When these fillers are further added to a specific boron nitride powder, 70 parts by mass or less of another filler may be added, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass total of 15 to 70 parts by mass of the olefin-aromatic vinyl compound-aromatic polyene copolymer and 85 to 30 parts by mass of the block boron nitride powder.

[0060] <Other additives> The composition may further contain one or more selected from a flame retardant and a surface modifier. The composition of the present invention can serve as a matrix for a cured body, and when cured, it has excellent filling properties for other materials. Therefore, the cured body containing one or more selected from these fillers, flame retardants, and surface modifiers tends to exhibit impact resistance and toughness even after curing.

[0061] <Flame retardant> Known flame retardants can be used in the composition of the present invention. From the viewpoint of maintaining a low dielectric constant and a low dielectric loss tangent, preferred flame retardants are known organophosphorus-based flame retardants such as phosphate esters or condensates thereof, known bromine-based flame retardants, and red phosphorus. Among phosphate esters, compounds having multiple xylenyl groups in the molecule are particularly preferred from the viewpoint of flame retardancy and a low dielectric loss tangent.

[0062] In addition to the flame retardant, antimony compounds such as antimony trioxide, antimony tetroxide, antimony pentoxide, and sodium antimonate, or nitrogen-containing compounds such as melamine, triallyl-1,3,5-triazine-2,3,4-(1H,3H,5H)-trione, and 2,4,6-triaryloxy-1,3,5-triazine may be added as a flame retardant aid. The total amount of these flame retardants and flame retardant aids is usually preferably 1 to 100 parts by mass per 100 parts by mass of the composition. Alternatively, 30 to 200 parts by mass of a polyphenylene ether (PPE) resin with a low dielectric constant and excellent flame retardancy may be used per 100 parts by mass of the flame retardant.

[0063] <Surface modifier> The composition of the present invention may contain various surface modifiers for the purpose of improving adhesion to fillers, copper plates, and wiring. The amount of the surface modifier used per 100 parts by mass of the composition of the present invention other than the surface modifier is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass. Examples of the surface modifier include various silane coupling agents and titanate coupling agents. Various silane coupling agents and titanate coupling agents may be used singly or in combination.

[0064] In the present invention, the fluidity of the composition can be adjusted by changing the compounding ratio of the "resin component," "curing agent," "monomer," "solvent," "other filler," or "other additives." Specifically, the composition of the present invention can take the form of a "thermoplastic composition," a "semi-cured state (such as a B-stage sheet)," or a "varnish."

[0065] The composition of the present invention can be obtained by mixing, dissolving, or melting one or more of a "resin component," "curing agent," "monomer," "solvent," "other filler," and "other additives," and can further include common additives added to ordinary resins, such as lubricants, stabilizers, antioxidants, weather resistance agents, and ultraviolet absorbers, to the extent that the object of the present invention is not impaired. Any known method can be used for mixing, dissolving, or melting these.

[0066] <Thermoplastic composition> The composition of the present invention can be molded in a substantially uncured state into shapes such as sheets, tubes, strips, pellets, etc. by known molding methods for thermoplastic resins under conditions that do not cause crosslinking. The molded article may be crosslinked (cured) after or during molding.

[0067] A preferred embodiment of the present composition is as follows. When the resin component contains a certain proportion or more of one or more resins selected from the hydrocarbon elastomer, polyether resin, olefin-aromatic vinyl compound-aromatic polyene copolymer not containing a cyclic olefin, or aromatic polyene resin, excluding resins that are liquid at room temperature, the composition is also easily molded into a thermoplastic resin in an uncured state. The thermoplastic properties of the above thermoplastic compositions can be utilized by molding them into various shapes, such as sheets, at or below the action temperature of the curing agent, and then laminating and combining them with semiconductor elements, wiring, or substrates as needed, followed by heat curing and bonding.

[0068] The composition of the present invention may be provided as a sheet obtained by molding the composition, heated and melted at a temperature below or equal to the curing agent's working temperature or decomposition temperature, using a known method. Forming into a sheet may be achieved by T-die extrusion, two-roll extrusion, or extrusion lamination onto a substrate film. In this case, the composition's composition, copolymer / monomer mass ratio, or solvent, resin components, and flame retardant are selected and adjusted so that the composition melts below or equal to the curing agent's working temperature or decomposition temperature and becomes solid at or near room temperature. In this case, the sheet is substantially uncured. After various processing and assembly steps, the sheet is finally treated at a temperature and time above the curing agent's working temperature or decomposition temperature to achieve complete curing. This method is a common technique used for ethylene-vinyl acetate resin-based crosslinked sealant sheets for solar cells (photovoltaic power generation devices).

[0069] <Molded body in semi-cured state (B-stage sheet, etc.)> The composition of the present invention can also be formed into a molded article, such as a sheet or tube, in a partially crosslinked state, for example, a state in which a portion of the curing agent contained therein has reacted and semi-cured (so-called B-stage state). Here, the semi-cured state is defined as a state in which the gel content of the resin component in the composition of the present invention is greater than 20% by mass and not more than 80% by mass, independently of the definition of the uncured state. The gel content is a value obtained by measurement in accordance with JIS K6796:1998. For example, by employing multiple curing agents and / or curing conditions with different curing temperatures, the composition can be semi-cured and the melt viscosity and fluidity can be controlled to achieve a B-stage state. That is, the curable resin or composition can be molded into an easily handleable B-stage sheet by a first curing step (partial curing), which can then be laminated and pressure-bonded to an electronic device or substrate, followed by a second curing step (complete curing) to form the final shape. In this case, the composition, i.e., the copolymer / monomer mass ratio, is selected, and if necessary, a solvent, resin component, and flame retardant are added. The composition, which further contains a curing agent such as a peroxide, is partially cured and adjusted to a sheet shape (B-stage state). After molding and assembling the device, the composition can be fully cured by heating under pressure. Known methods can be used to partially cure the composition. For example, peroxides with different decomposition temperatures are used in combination, and the composition is treated for a predetermined time at a temperature at which only one of the peroxides is substantially active to obtain a semi-cured sheet. Finally, the sheet is fully cured by treating the sheet for a sufficient time at a temperature at which all of the curing agents are active.

[0070] Furthermore, the molded article may be a sheet. The sheet may be uncured (semi-cured) to the extent that it can maintain its sheet shape, or may be fully cured. The degree of curing of the composition can be quantitatively measured by known dynamic mechanical analysis (DMA).

[0071] <Varnish-like composition and molded article thereof> The composition of the present invention can also be made into a viscous liquid varnish by adjusting its composition and blending ratio. For example, a varnish can be obtained by using a sufficient amount of solvent and / or an appropriate amount of liquid monomer. When used as a varnish, it is preferable to add an appropriate solvent to the composition of the present invention. The solvent is used to adjust the viscosity and fluidity of the composition as a varnish. A solvent with a high boiling point at atmospheric pressure, i.e., low volatility, contributes to a uniform thickness of the applied film; therefore, a solvent with a boiling point above a certain level is preferred. A preferred boiling point is approximately 110°C to 300°C at atmospheric pressure. Examples of solvents suitable for such varnishes include toluene, xylene, mesitylene, ethylbenzene, limonene, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether. The amount of the solvent used is preferably in the range of 10 to 2,000 parts by mass per 100 parts by mass of the composition of the present invention.

[0072] The varnish can be applied to or impregnated into a substrate, and the solvent or the like can be removed by drying or the like to produce an uncured or semi-cured molded article. This molded article generally has the form of a sheet, film, or tape. In this embodiment, the obtained uncured or semi-cured molded article is cured.

[0073] The cured product of the present invention may be in the form of a sheet. The shape and thickness of the sheet are optional. For CCL or FCCL, the thickness is generally about 10 μm to 1 mm, and as an interlayer insulating layer it is generally 10 μm to 200 μm, and as an insulating layer in various packaging it is generally about 5 μm to 50 μm. The method for molding the cured composition sheet is also optional, and known methods can be used. Examples of such methods include a casting method using varnish, etc., an extrusion method, an extrusion lamination method, and a coating method.

[0074] <Curing> Resin-filled boron nitride plates can be cured by known methods, taking into account the curing conditions (temperature, time, pressure) of the included curing agent. When the curing agent used is a peroxide or azo-based agent, the curing conditions can be determined by taking into account the half-life temperature and other factors disclosed for each curing agent.

[0075] <Cured product of the composition> The dielectric breakdown voltage of the cured product obtained from the composition of the present invention is 5 kV / mm or more, preferably 10 kV / mm or more. The dielectric constant and dielectric dissipation factor are measured by a known resonator method. In this specification, the resonator method is performed at a measurement frequency of 40 GHz. The dielectric constant of the cured product may be 3.0 or more and 5.0 or less, preferably 3.5 or more and 4.5 or less. The dielectric dissipation factor of the cured product may be 0.0002 or more and 0.0030 or less, preferably 0.0002 or more and 0.0020 or less. These values ​​are preferred for high-frequency electrical insulating materials, for example, at 3 GHz or more. The thermal conductivity of the cured product obtained from the composition of the present invention is preferably 3 W / (m·K) or more, more preferably 5 W / (m·K) or more, and even more preferably 25 W / (m·K) or less.

[0076] The coefficient of linear expansion (CTE) from 0°C to 200°C of the cured product obtained from the composition of the present invention is preferably 150 ppm or less, more preferably 80 ppm or less. Those skilled in the art can determine the formulation of a composition having the above physical property parameters and produce a cured product by referring to the information described in this specification and publicly known documents. The cured product obtained from the composition of the present invention can exhibit practically sufficient heat resistance and mechanical properties at high temperatures, even under conditions where the monomer in the composition and the aromatic polyene as a component of the monomer are kept below a certain ratio.

[0077] <Uses of the cured composition> The cured composition of the present invention can be used as a substrate or base material, such as a single-layer or multilayer printed circuit board, a flexible printed circuit board, a single-layer or multilayer CCL (copper clad laminate) board, or a single-layer or multilayer FCCL (flexible copper clad laminate) board. It is also useful as an insulating heat dissipation material for interposers and rewiring layers. The present invention also relates to various three-dimensional integrated circuit packaging packages and chiplets that contain a cured resin-filled boron nitride plate of the present invention. Furthermore, the composition is useful as an insulating heat dissipation material for multilayer antenna substrates that contain RFICs and high-frequency wiring (antenna feed lines) in layers beneath the antenna structure of Massive MIMO (phased array antenna / multilayer substrate for transmitter circuit) for 5G / 6G base stations. It is also useful as an insulating heat dissipation material for switching integrated circuits (ASICs) in next-generation optical interconnect components (switching integrated circuits for optical transceivers in co-packages).

[0078] In one embodiment of the present invention, there is also provided a method for producing the copolymer, which includes copolymerizing an α-olefin, a cyclic olefin, an aromatic vinyl compound, and an aromatic polyene by coordination polymerization.

[0079] Coordination polymerization is a polymerization method using a coordination polymerization catalyst consisting of a transition metal compound and a co-catalyst. The transition metal compound is preferably a transition metal compound containing zirconium, hafnium, titanium, iron, nickel, cobalt, or palladium. In particular, for copolymerizing cyclic olefin monomers, a transition metal compound containing zirconium, titanium, nickel, iron, or palladium is preferred. The most preferred coordination polymerization catalyst is a coordination polymerization catalyst consisting of a transition metal compound represented by the following general formula (1) and a co-catalyst. More preferably, the production method may include a step of copolymerizing each of the monomers of olefins such as α-olefins and cyclic olefins, aromatic vinyl compounds, and aromatic polyenes using a polymerization catalyst consisting of a transition metal compound represented by the following general formula (1) and a co-catalyst.

[0080] General formula (1) [ka]

[0081] In the above formula, A and B are each independently a group selected from an unsubstituted or substituted cyclopentaphenanthryl group, an unsubstituted or substituted benzoindenyl group, an unsubstituted or substituted cyclopentadienyl group, and an unsubstituted or substituted indenyl group. Y is a methylene group, silylene group, ethylene group, germylene group, or boron residue having a bond to A and B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. The substituents may be different or the same. Y may also have a cyclic structure. Most preferably, Y is a methylene group having a bond to A and B and having hydrogen or a hydrocarbon group having 1 to 15 carbon atoms (which may contain 1 to 3 nitrogen, oxygen, sulfur, phosphorus, or silicon atoms) as a substituent. X is hydrogen, halogen, an alkyl group having 1 to 15 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkylaryl group having 8 to 12 carbon atoms, a silyl group having a hydrocarbon substituent having 1 to 4 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a dialkylamide group having an alkyl substituent having 1 to 6 carbon atoms. M is a transition metal, and may preferably be zirconium, hafnium, or titanium.

[0082] To obtain a copolymer with a relatively low molecular weight and low viscosity when made into a varnish, A and B in the above general formula (1) are preferably each independently selected from an unsubstituted or substituted cyclopentadienyl group or an unsubstituted or substituted indenyl group. It is particularly preferable to use a transition metal compound having both an unsubstituted or substituted cyclopentadienyl group and an unsubstituted or substituted indenyl group. To obtain a copolymer with a high aromatic polyene content, i.e., a copolymer with a high number of vinyl and / or vinylene groups derived from aromatic polyene monomer units per number-average molecular weight, it is preferable to use a transition metal compound having at least one group selected from an unsubstituted or substituted indenyl group or an unsubstituted or substituted benzoindenyl group. Copolymers with a high aromatic polyene monomer unit content can increase the crosslink density of the cured product, resulting in a cured product with a storage modulus of 5 MPa or more measured at 280°C.

[0083] The cocatalyst in the polymerization catalyst of the present invention may be a known cocatalyst used in combination with a transition metal compound. Preferred examples of such cocatalysts include aluminum compounds and boron compounds. Alumoxanes such as methylaluminoxane (also referred to as methylalumoxane or MAO) are suitable aluminum compounds. Aluminum alkyls such as triisobutylaluminum and triethylaluminum may also be used. Aluminum compounds and boron compounds may also be used together. Examples of such cocatalysts include the cocatalysts and alkylaluminum compounds described in EP 0872492A2, JP 11-130808A, JP 9-309925A, WO 00 / 20426, EP 0985689A1, and JP 6-184179A.

[0084] Examples of boron compounds include trispentafluorophenylborane, triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityltetrakis(pentafluorophenyl)borate}, lithium tetrakis(pentafluorophenyl)borate, trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(n-butyl)ammonium tetra(p-tolyl)phenylborate, tri(n-butyl)ammonium tetra(p-ethylphenyl)borate, tri(n-butyl)ammonium tetra(pentafluorophenyl)borate, trimethylammonium tetra(p-tolyl)borate, trimethylammonium tetrakis-3,5-dimethylphenylborate, and triethylammonium tetrakis-3 ,5-dimethylphenylborate, tributylammonium tetrakis-3,5-dimethylphenylborate, tributylammonium tetrakis-2,4-dimethylphenylborate, anilinium tetrakispentafluorophenylborate, N,N'-dimethylanilinium tetraphenylborate, N,N'-dimethylanilinium tetrakis(p-tolyl)borate, N,N'-dimethylanilinium tetrakis(m-tolyl)borate, N,N'-dimethylanilinium tetrakis(2,4-dimethylphenyl)borate, N,N'-dimethylanilinium tetrakis(3,5-dimethylphenyl)borate, N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N'-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N'-2,4,5-pentamethylanilinium tetraphenylborate, N,N'-2,4,Examples include 5-pentaethylanilinium tetraphenylborate, di-(isopropyl)ammonium tetrakispentafluorophenylborate, di-cyclohexylammonium tetraphenylborate, triphenylphosphonium tetraphenylborate, tri(methylphenyl)phosphonium tetraphenylborate, tri(dimethylphenyl)phosphonium tetraphenylborate, triphenylcarbenium tetrakis(p-tolyl)borate, triphenylcarbenium tetrakis(m-tolyl)borate, triphenylcarbenium tetrakis(2,4-dimethylphenyl)borate, triphenylcarbenium tetrakis(3,5-dimethylphenyl)borate, tropylium tetrakispentafluorophenylborate, tropylium tetrakis(p-tolyl)borate, tropylium tetrakis(m-tolyl)borate, tropylium tetrakis(2,4-dimethylphenyl)borate, and tropylium tetrakis(3,5-dimethylphenyl)borate. Although boron-containing promoters in which the fluorine-substituted aromatic group is a phenyl group have been exemplified herein, boron-containing promoters having a fused aromatic group such as a fluorine-substituted naphthyl group can also be preferably used. Among these, the most preferred boron promoters are those having boron and a fluorine-substituted aromatic group bonded thereto. Examples include trispentafluorophenylborane, triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityl tetrakis(pentafluorophenyl)borate}, lithium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetra(pentafluorophenyl)borate, tropylium tetrakispentafluorophenylborate, and N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate. Particularly preferred are triphenylcarbenium tetrakis(pentafluorophenyl)borate {trityl tetrakis(pentafluorophenyl)borate} and N,N'-dimethylanilinium tetrakis(pentafluorophenyl)borate is used. These most preferred boron-containing cocatalysts are also known as TRI-FABA or TRI-FAB, and DAN-FABA or DAN-FAB, respectively, and can be purchased from Tosoh Finechem Co., Ltd. or Kanto Chemical Co., Ltd.

[0085] The co-catalyst is used in an aluminum atom / transition metal atom ratio relative to the metal of the transition metal compound of 0.1 to 100,000, preferably 10 to 10,000. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100,000 or less is economically advantageous. The transition metal compound and co-catalyst may be mixed and prepared outside of polymerization equipment, or may be mixed inside the equipment during polymerization.

[0086] In particular, the aluminum atom / transition metal atomic ratio of the co-catalyst, such as alumoxane, relative to the metal in the transition metal compound is preferably 0.1 to 100,000, more preferably 10 to 10,000. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100,000 or less is economically advantageous. When a boron compound is used as the co-catalyst, the boron atom / transition metal atomic ratio is preferably 0.1 to 100, more preferably 0.1 to 10, and most preferably in the range of 0.8 to 1.2. A ratio of 0.1 or more can effectively activate the transition metal compound, while a ratio of 100 or less is economically advantageous.

[0087] In a preferred embodiment, a co-catalyst containing a boron compound as an essential component and an aluminum compound as needed may be used. By using a boron compound as a co-catalyst, the amount of metal components such as aluminum derived from the aluminum compound contained in the final copolymer can be reduced, and the dielectric constant and dielectric loss tangent values ​​of the final uncured copolymer, or the dielectric constant and dielectric loss tangent values ​​of the single cured product or composition, can be reduced to particularly preferred ranges. For example, when the copolymer is cured alone, the dielectric constant can be less than 2.5 and the dielectric loss tangent can be less than 0.0008, preferably less than 0.0006.

[0088] In one embodiment, an olefin-aromatic vinyl compound-aromatic polyene copolymer can be provided in which the total content of metals derived from the catalyst and co-catalyst is 1500 ppm or less, preferably 750 ppm or less, and most preferably 500 ppm or less. Here, the metal content derived from the catalyst and co-catalyst is defined as the sum of the respective contents of the transition metal elements (as described above) used in the catalyst and the boron and / or aluminum derived from the boron compound and / or aluminum compound used in the co-catalyst, and can be defined as the sum of the respective contents of zirconium, hafnium, titanium, iron, nickel, palladium, cobalt, boron, and aluminum. Particularly preferably, the metal derived from the catalyst may be zirconium, and the metal derived from the co-catalyst may be aluminum and boron, and the metal content derived from the catalyst and co-catalyst may be the sum of the respective contents of zirconium, aluminum, and boron. Note that, in this specification, boron is included in the category of metal. When cured alone, an olefin-aromatic vinyl compound-aromatic polyene copolymer having a total metal content of 1500 ppm or less, preferably 750 ppm or less, and most preferably 500 ppm or less can achieve the properties of a dielectric constant of less than 2.5 at 40 GHz and a dielectric loss tangent of less than 0.0008, preferably less than 0.0006. In other words, it is suitable for the cured product of the composition of the present invention in that it gives a cured product with excellent low dielectric properties. [Example]

[0089] The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to the following examples.

[0090] <Boron nitride powder> As boron nitride powders constituting the examples of the present invention, BN1 and BN2 were produced by the methods described in WO 2022 / 071225 and WO 2020 / 004600. As a comparative example, boron nitride agglomerated powder consisting of flaky boron nitride (boron nitride SGPS manufactured by Denka Co., Ltd.) was used.

[0091] <Purity of boron nitride powder> Boron nitride powder was subjected to alkaline decomposition with sodium hydroxide, and ammonia was distilled from the decomposition liquid by steam distillation and collected in an aqueous boric acid solution. This collected liquid was then titrated with a normal sulfuric acid solution. The nitrogen atom (N) content in the boron nitride powder was calculated from the titration results. The hexagonal boron nitride (hBN) content in the boron nitride powder was determined from the obtained nitrogen atom content using formula (1), and the purity of the hexagonal boron nitride powder was calculated. The formula weight of hexagonal boron nitride was 24.818 g / mol, and the atomic weight of the nitrogen atom was 14.006 g / mol. Hexagonal boron nitride (hBN) content in the sample [mass%] = Nitrogen atom (N) content [mass%] × 1.772 Formula (1)

[0092] <Average particle size of boron nitride powder> The average particle size of the boron nitride powder was measured in accordance with ISO 13320:2009 using a Beckman Coulter laser diffraction / scattering particle size distribution analyzer (instrument name: LS-13 320). The boron nitride powder was not homogenized during the measurement. When measuring the particle size distribution, water was used as the solvent for dispersing the boron nitride powder, and hexametaphosphoric acid was used as the dispersant. The refractive index of water was 1.33, and the refractive index of the boron nitride powder was 1.80.

[0093] <Specific surface area of ​​boron nitride powder> The specific surface area of ​​the boron nitride powder was calculated using the BET single-point method using nitrogen gas, in accordance with JIS Z8830:2013 "Method for measuring the specific surface area of ​​powders (solids) by gas adsorption." The specific surface area was measured using a specific surface area measuring device (device name: Quantasorb) manufactured by Yuasa Ionics. The measurement was performed after drying and degassing the boron nitride powder at 300°C for 15 minutes.

[0094] <Compression strength of agglomerated particles (compression strength)> The crushing strength of the agglomerated particles was measured in accordance with the description in JIS R 1639-5:2007 "Fine ceramics - Measurement methods for granule characteristics - Part 5: Single granule crushing strength." The crushing strength σ (unit: MPa) was calculated using the formula σ = α × P / (π × d2) from the dimensionless number α (α = 2.48), which changes depending on the position within the particle, the crushing test force P (unit: N), and the particle diameter d (unit: μm) of the agglomerated particles being measured. The crushing strength was calculated at the point where the cumulative destruction rate of 20 particles was 63.2%.

[0095] <Orientation index of boron nitride powder> The orientation index of the boron nitride powder was determined from the results of measurements using powder X-ray diffraction. First, boron nitride powder was filled into the recess of a glass cell with a 0.2 mm depth recess attached to an X-ray diffractometer (Rigaku Corporation, product name: ULTIMA-IV). The measurement sample was prepared by compacting the powder using a powder sample molding machine (Amenatec Corporation, product name: PX700) at a set pressure M. If the surface of the packed material compacted by the molding machine was not smooth, it was smoothed manually before measurement. The measurement sample was irradiated with X-rays, and after baseline correction, the peak intensity ratio of the (002) and (100) planes of boron nitride was calculated. The orientation index [I(002) / I(100)] was determined based on this value. Table 1 shows the analytical values ​​of the boron nitride powders used in the example and comparative examples.

[0096] [Table 1]

[0097] The method for producing the copolymer used in the present invention is shown in the following Synthesis Examples. The copolymers obtained in the Synthesis Examples were analyzed by the following means. The contents of vinyl group units derived from ethylene, cyclic olefin, styrene, ethylvinylbenzene, and divinylbenzene in the copolymer were determined by the following methods: 1 H-NMR measurement and quantitative mode 13C-NMR measurement was performed, and the analysis was carried out by a known method based on the area intensity of the obtained peak. The sample was dissolved in heavy 1,1,2,2-tetrachloroethane, and the measurement was carried out at 80 to 130°C. In this specification, the copolymer may also be referred to as "resin."

[0098] The molecular weight was determined as a number average molecular weight (Mn) converted to standard polystyrene using GPC (gel permeation chromatography) under the following conditions.

[0099] Column: Two TSK-GEL MultiporeHXL-M φ7.8×300 mm (manufactured by Tosoh Corporation) connected in series were used. Column temperature: 40℃ Solvent: THF Flow rate: 1.0 ml / min. Detector: RI detector

[0100] <Gel content> The gel fraction was determined as boiling toluene insoluble matter according to ASTM D2765-84. If the sample contained boron nitride powder, the mass of the powder was corrected to determine the gel fraction of the resin.

[0101] <Dielectric constant and dielectric loss (dielectric loss tangent)> The dielectric loss tangent was measured using the cavity resonator perturbation method (Agilent Technologies 8722ES Network Analyzer, Keysight Technologies Split Cylinder Resonator 40 GHz) at 23°C and 40 GHz using a 0.1 mm x 25 mm x 30 mm sample cut from the sheet. Measurements were taken for both the uncured and cured state.

[0102] <Quantitative determination of metal content in copolymers> The metal content (in the example below, the content of transition metal elements used in the metal catalyst, and the content of boron and aluminum used in the promoter) was determined as follows: In addition, the contents of hafnium, titanium, iron, nickel, cobalt, and palladium were also quantified. Measurement was performed by ICP atomic emission spectrometry under the following conditions in accordance with JIS K 0116:2014. 0.5 g of the composition to be measured was weighed into a platinum crucible and incinerated on a hot plate, an electric stove, and an electric furnace (gradually heated to 600°C). 0.5 ml of HCl (1+1) (i.e., a 1:1 volumetric mixture of hydrochloric acid and water) and ultrapure water were added to the residue, and after heating and dissolution, the mixture was adjusted to a constant volume of 5 ml to form a test solution, which was then quantitatively analyzed by ICP emission spectrometry (using an Agilent 5110VDV).

[0103] <Measurement of dielectric breakdown voltage> The cured sheet was cut using a cutter to a length of 50 mm from the edge to serve as a measurement sample. One of the cut measurement samples was placed on a copper plate in a measurement jig (manufactured by Onishi Electronics Co., Ltd.), and a 40 mm square x 1 mm thick copper plate was placed in the center. The measurement sample was then filled with insulating oil (manufactured by 3M, product name: Novec 7200) so that the measurement sample was fully immersed. Next, electrodes were lowered from above the measurement sample, creating a situation where electricity could be passed between the device and the measurement sample. The breakdown voltage was measured using an ultra-high voltage withstand voltage tester (manufactured by Keisoku Giken Kenkyusho Co., Ltd.) in accordance with JIS C 2110-1:2016.

[0104] <Thermal conductivity evaluation> Measurement of the thermal conductivity H (unit: W / (m K)) of the cured sheet: The thermal conductivity H is calculated by multiplying the thermal diffusivity A (unit: m 2 / sec), density B (unit: kg / m 3 The thermal diffusivity A was calculated from the values ​​of the specific heat capacity C (unit: J / (kg·K)) using the formula H = A × B × C. The thermal diffusivity A was measured by the laser flash method using an evaluation sheet cut into a length of 10 mm, width of 10 mm, and thickness of 0.3 mm. The measurement device used was a xenon flash analyzer (manufactured by NETZSCH, product name: LFA447 NanoFlash). The density B was measured using the Archimedes method. The specific heat capacity C was measured using a DSC (manufactured by Rigaku, product name: ThermoPlusEvoDSC8230).

[0105] <Copolymer P-1 (ethylene-styrene-divinylbenzene copolymer)> Ethylene-styrene-divinylbenzene copolymer P-1 was produced according to the production method using the catalyst dimethylmethylenebis(cyclopentadienyl)zirconium dichloride described in WO 2022 / 014599 and the production method using a boron compound as a cocatalyst described in the examples of WO 2017 / 122295.

[0106] <Copolymer P-2 (ethylene-norbornene-styrene-divinylbenzene copolymer)> The raw material divinylbenzene (DVB) was "Divinylbenzene (81%)" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid at room temperature, a mixture of meta and para isomers containing 81% by mass of divinylbenzene, with the remainder being ethylvinylbenzene). The raw material was norbornene (75%, toluene solution) manufactured by Maruzen Petrochemical Co., Ltd., which was first mixed with a small amount of triisobutylaluminum (TIBA) and stirred at room temperature. The mixture was then purified by distillation under nitrogen. A 10-L polymerization vessel equipped with a heating and cooling jacket and a stirrer was used for the polymerization. The interior of the vessel was first thoroughly dried and purged with nitrogen. Then, 1.4 kg of toluene, 0.23 kg of pure norbornene, 3.0 kg of styrene, and 0.60 kg of 81% divinylbenzene were charged, and approximately 20 L of dry nitrogen was bubbled through at an internal temperature of 60 °C. The reactor was then purged with ethylene gas, and 6 mmol of TIBA (Kanto Chemical Co., Inc.) was added and stirred. The internal temperature was stabilized at 80°C, and the internal pressure of the reactor was increased to 0.1 MPaG (gauge) with nitrogen and stabilized. Then, from a catalyst tank installed above the reactor, 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (formula (1)) and 2 mmol of TIBA was dissolved in 210 μmol of tritylium tetrakis(pentafluorophenyl)borate and stirred. The catalyst solution was added to the reactor to initiate polymerization. The internal temperature was maintained at 60°C, and the internal pressure was maintained at 0.1 MPaG (ethylene pressure). When ethylene consumption reached 100 g, 50 g of isopropanol (a polymerization terminator) was added to the reactor to terminate the polymerization. The obtained polymerization liquid was poured in small amounts into a sufficiently large amount of a methanol / acetone mixed solution, and the precipitated polymer was recovered by stirring and filtering. The polymer was then thoroughly dried in vacuum at room temperature to obtain P-2, an ethylene-norbornene-styrene-divinylbenzene copolymer.

[0107] Formula (1) [ka]

[0108] <Copolymer P-3 (ethylene-norbornene-styrene-divinylbenzene copolymer)> Similar to P-2, except that 2.0 kg of toluene, 2.0 kg of pure norbornene, 0.80 kg of styrene, and 0.20 kg of divinylbenzene (81% divinylbenzene) were charged, and polymerization was continued while maintaining the internal temperature at 90 ° C and the internal pressure at 0.1 MPaG in ethylene pressure. When the ethylene consumption reached 40 g, 50 g of isopropanol (a polymerization terminator) was added to the polymerization vessel to terminate the polymerization. The resulting polymerization liquid was poured into a sufficiently large amount of methanol / acetone mixed solution in small amounts, and the precipitated polymer was recovered by stirring and filtering. The polymer was then thoroughly vacuum dried at room temperature to obtain ethylene-norbornene-styrene-divinylbenzene copolymer P-3.

[0109] Since P-2 and P-3 obtained in each production example contained small amounts of residual monomer and solvent, they were redissolved in toluene, and the solution was poured in small amounts into a sufficiently large amount of methanol / acetone mixed solution. The precipitated polymer was stirred, filtered, and dried at room temperature under vacuum for 24 hours to obtain purified polymers. The compositions and molecular weights of the obtained P-1 to P-3 are shown in Table 2. The purified polymer was again dissolved in toluene to make a 50% by mass toluene solution (varnish).

[0110] <Preparation and evaluation of copolymer mono-cured bodies> To varnishes containing 50% by mass of each of P-1 to P-3, 0.75% by mass of initiator was added and dissolved relative to the mass of the resin. Perbutyl P was used for P-1, and the azo-based initiator VR-110 was used for P-2 and P-3. These varnishes were poured into a Teflon (registered trademark) mold (frame length 7 cm, width 7 cm, thickness 0.2 mm) on a PET sheet placed on a glass plate, thoroughly air-dried at 25°C, and then further dried in a vacuum dryer at 100°C for 3 hours to obtain uncured sheets that were substantially free of solvent. If necessary, multiple uncured sheets were stacked to achieve the required thickness for each measurement. A Teflon sheet was placed on a smooth metal plate, and the uncured sheet was then placed on top of that. A mold of the required thickness, Teflon sheet, and smooth metal plate were then placed on top of that. For P-1 and P-2, the sheets were heated in a vacuum press under a load of 5 MPa at 150°C for 30 minutes and then at 200°C for 30 minutes. For P-3, the sheets were heated at 200°C for 30 minutes and then at 250°C for 30 minutes. The Teflon sheet and Teflon mold were then removed to obtain a cured sheet (a sheet cured with the resin alone). The gel fraction, dielectric constant, and dielectric loss tangent of the resulting cured sheets were measured (all at 23°C and 40 GHz). The results are shown in Table 2.

[0111] [Table 2]

[0112] Example 1: Preparation of composition and preparation of cured sheet Perbutyl P was added as a curing agent at 0.75% by mass relative to the mass of P-1 (mass of resin components) to a toluene varnish containing P-1 (P-1 concentration: 50% by mass). Boron nitride powder BN-1 (manufactured by Denka Co., Ltd., average particle size: 40 μm, thermal conductivity: 150 W / m·K) was then added as an inorganic filler to a mass ratio of 30:70 (volume ratio of 50:50) of P-1:BN-1. The mixture was then mixed and kneaded at 1600 rpm for 3 minutes using a Thinky Mixer. The resulting composition was applied to a Teflon sheet to a thickness of 0.20 mm after drying and curing. The toluene was then air-dried at 60°C until no weight change was observed. This resulted in a semi-cured composition. This sheet was placed on a smooth metal plate, a 0.12 mm thick metal formwork was placed on the sheet, and a smooth metal plate was placed on top of that. The sheet was then subjected to a pressure-heat curing treatment using a press at 150°C for 30 minutes at a surface pressure of 5 MPa, and then at 200°C for 30 minutes, to obtain a cured sheet with a thickness of 0.12 mm.

[0113] <Example 2> A cured sheet was obtained in the same manner as in Example 1, except that the resin was changed to a toluene varnish in which P-2 was dissolved (P-2 concentration: 50% by mass).

[0114] Example 3 A cured sheet was obtained in the same manner as in Example 1, except that the resin was changed to a toluene varnish in which P-3 was dissolved (P-3 concentration: 50% by mass).

[0115] <Comparative Example 1> The same procedure as in Example 1 was carried out except that a toluene varnish in which P-3 was dissolved (P-3 concentration: 50% by mass) was used as the resin and SGPS was used as the boron nitride. However, under the present conditions where the mass ratio of P-3:SGPS was 30:70, no uniform composition could be obtained even when the mixing conditions were changed in various ways, and subsequent sheet formation and evaluation could not be carried out.

[0116] <Comparative Example 2> The P-3:SGPS mass ratio of Comparative Example 1 was gradually decreased by changing the ratio to 30:40, and a uniform, moldable composition was obtained. The procedure was then repeated as in Example 1 to obtain a cured sheet.

[0117] The evaluation results of the cured sheets obtained in the Examples and Comparative Examples are shown in Table 3. Values ​​in the table indicate parts by mass unless otherwise specified. The cured sheets obtained in each Example exhibited high thermal conductivity and low dielectric constant and dielectric loss tangent values ​​within the preferred ranges of the present invention. Furthermore, it was found that the presence of cyclic olefin monomer units in the olefin-aromatic vinyl compound-aromatic polyene copolymer resulted in a low dielectric loss tangent value for the resulting cured sheet. In Comparative Example 1, a uniform composition was not obtained, so preparation and evaluation of the cured sheet was abandoned. The sheet obtained in Comparative Example 2 had a low thermal conductivity of 1.8 W / m·K.

[0118] [Table 3]

Claims

1. 15 to 70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer having a number average molecular weight of 500 or more and 15000 or less, 85 to 30 parts by mass of boron nitride powder that satisfies all of the following conditions (A) to (C) and A composition comprising a total of 100 parts by mass of the following: A composition in which the dielectric constant of the cured body of the composition, as measured by the resonator method at a measurement frequency of 40 GHz, is 3.0 or more and 5.0 or less, and the dielectric loss tangent is 0.0002 or more and 0.0020 or less. (A) The average particle size of the boron nitride powder is 3 μm or more and 100 μm or less. (B) Crushing strength of 6 MPa or more and 20 MPa or less. (C) The orientation index of the boron nitride powder is 5 or higher and 20 or lower.

2. The composition according to claim 1, wherein the purity of the boron nitride powder is 95% by mass or more.

3. The composition according to claim 1 or 2, wherein the olefin-aromatic vinyl compound-aromatic polyene copolymer satisfies all of the following (1) to (5). (1) The number-average molecular weight of the copolymer is 500 or more and 15,000 or less. (2) The aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more carbon atoms and 20 or fewer carbon atoms, and the content of aromatic vinyl compound monomer units is 0.1% by mass or more and 70% by mass or less. (3) The olefin monomer unit is one or more selected from α-olefin monomer units having 2 to 30 carbon atoms and cyclic olefin monomer units having 7 to 30 carbon atoms, and its content is 5% by mass or more and 95% by mass or less. (4) The aromatic polyene monomer is one or more selected from polyenes having 5 to 20 carbon atoms and having multiple vinyl groups and / or vinylene groups in the molecule, and the content of vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is 2 to 30 per number average molecular weight. (5) The total of olefin monomer units, aromatic vinyl compound monomer units, and aromatic polyene monomer units is 100% by mass.

4. The composition according to claim 3, wherein the olefin monomer units constituting the olefin-aromatic vinyl compound-aromatic polyene copolymer include at least cyclic olefin monomer units.

5. The composition according to claim 1 or 2, wherein the cured product obtained by curing the olefin-aromatic vinyl compound-aromatic polyene copolymer alone has a dielectric constant of less than 2.5 and a dielectric loss tangent of less than 0.0008, as measured by the resonator method at a measurement frequency of 40 GHz and 25°C.

6. A cured body of the composition according to claim 1 or 2.

7. The cured body according to claim 6, wherein the dielectric constant measured by the resonator method at a measurement frequency of 40 GHz is 3.0 or more and 5.0 or less, and the dielectric loss tangent is 0.0002 or more and 0.0020 or less.

8. The cured body according to claim 6, wherein the thermal conductivity is 3 W / (m·K) or more.

9. A high-frequency transmission circuit comprising the cured body described in claim 6.

10. A single-layer or multi-layer CCL (copper-clad laminate) substrate, a single-layer or multi-layer FCCL (flexible copper-clad laminate) substrate, an interlayer insulating material, or an antenna, comprising the cured body described in claim 6.

11. A three-dimensional high-integration package or chiplet comprising the cured body described in claim 6.