Low dielectric heat-dissipating material

Abstract

This composition contains, as a total of 100 parts by mass, 15-70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer, and 85-30 parts by mass of a boron nitride powder satisfying all of the following (A)-(C). (A) The average particle size of the boron nitride powder is 3-100 μm, inclusive. (B) The crushing strength is 6-20 MPa, inclusive. (C) The orientation index of the boron nitride powder is 5-20, inclusive.

Description

Low dielectric heat dissipation material

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

[0002] As Moore's Law approaches its limits due to increasing interconnect density, in addition to conventional semiconductor device interconnect density, high integration (chipletization) is required through three-dimensional, 3D packaging and functional integration between component devices. As interconnect density within devices increases, devices are becoming increasingly multilayered, miniaturized, and denser. To prevent high-frequency signal delays and noise, insulating materials with low dielectric constants and low dielectric loss tangents are particularly required for substrates, interposers, and redistribution layer wiring. Furthermore, because temperature changes in insulating materials, not just devices, can affect circuit characteristics, efficient heat removal is required for multilayered, miniaturized, and densely packed devices. 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 / 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 formability, making it difficult to achieve multilayer and high-density wiring, and also present issues with adhesion to copper foil. Furthermore, there are also issues with the ability to incorporate heat-dissipating fillers to ensure thermal conductivity. Therefore, attention has been focused on hydrocarbon-based resins with inherently low dielectric properties. 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 non-polar vinyl compound. With this technology, only one of the two vinyl groups in the aromatic polyene (divinylbenzene) is selectively copolymerized, preserving the remaining vinyl group. This facilitates the production of cross-linkable hydrocarbon-based copolymer macromonomers with aromatic vinyl groups as functional groups, which exhibit high reactivity (cross-linkability). 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 a wide range of physical properties from soft to hard can be achieved by selecting the appropriate composition and auxiliary materials (Patent Documents 2 and 3). Furthermore, these copolymers can be filled with a relatively large amount 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 described in Patent Document 4 did not adequately resolve the problem of thermal conductivity. Inorganic fillers such as alumina, silicon nitride, and aluminum nitride, which are commonly used to impart thermal conductivity, have an extremely high dielectric constant of approximately 10, resulting in a problem of particularly high dielectric constants in 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 the like 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 economical (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.

[0005] Japanese Patent Application Laid-Open No. 2009-161743 International Publication No. 2021 / 112087 International Publication No. 2022 / 014599 Japanese Patent Application Laid-Open No. 2010-280860 Japanese Patent Application Laid-Open No. 2024-006085

[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.

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

[0008] Aspect 1: A composition comprising 15 to 70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer, and 85 to 30 parts by mass of boron nitride powder satisfying all of the following (A) to (C), for 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) the crushing strength is 6 MPa or more and 20 MPa or less; and (C) the orientation index of the boron nitride powder is 5 or more and 20 or less.

[0009] Aspect 2: The composition of aspect 1, wherein the purity of the boron nitride powder is 95% by mass or more.

[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 from 500 to 30,000; (2) the aromatic vinyl compound monomer is an aromatic vinyl compound having from 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer unit is from 0.1 to 70 mass%; (3) the olefin monomer unit is one or more selected from an α-olefin monomer unit having from 2 to 30 carbon atoms and a cyclic olefin monomer unit having from 7 to 30 carbon atoms, and the content thereof is from 5 to 95 mass%; (4) the aromatic polyene monomer is one or more selected from polyenes having from 5 to 20 carbon atoms and having a plurality of vinyl groups and / or vinylene groups in the molecule, and the content of the vinyl groups and / or vinylene groups derived from the aromatic polyene monomer unit is from 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 The 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: The 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 dissipation factor of less than 0.0008, 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: The cured product according to aspect 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: The cured product according to aspect 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 aspects 6 to 9.

[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.

[0021] In this 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 a copolymer. Furthermore, boron nitride powder satisfying conditions (A) to (C) may be simply referred to as a specific boron nitride powder. Numerical ranges in this specification include their upper and lower limits unless otherwise specified. The term "sheet" in this specification also encompasses the concept of a film. Furthermore, the term "film" in this specification also has the same meaning as "sheet." Furthermore, the term "film" in this specification also encompasses the concept of a sheet. The term "cured state" in this 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 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 present composition may contain an olefin-aromatic vinyl compound-aromatic polyene copolymer and a boron nitride powder satisfying all of the following conditions (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. The boron nitride powder satisfying 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, this type of 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" in this specification refers to the above-mentioned "lump boron nitride." 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 ISO 13320:2009. Specifically, it is measured by the method described in the Examples of this specification. The laser diffraction scattering particle size distribution analyzer that can be used is, 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 crushing strength in this specification refers to a value measured in accordance with the description in JIS R1639-5:2007 "Fine ceramics - Measurement of granule characteristics - Part 5: Single granule crushing strength." The orientation index in this specification refers to the ratio of the peak intensity in the (002) plane of boron nitride measured with an X-ray diffractometer to the peak intensity in the (100) plane, and can be calculated as [I(002) / I(100)]. An orientation index of boron nitride powder of 5 or more and 20 or less, preferably 5 or more and 15 or less, indicates that boron nitride primary particles are originally tabular and have very high orientation as they are, but that an index within this range indicates that multiple boron nitride primary particles have aggregated in a disordered manner, forming clumps and bonding together, thereby reducing orientation. The bond strength of the present bulk structure is expressed by the preferred value of the crushing strength, and specifically, the lower limit of the crushing strength may be 6 MPa or more, preferably 8 MPa or more, further preferably 10 MPa or more, and 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-mentioned methods for producing boron nitride powder are described in WO 2022 / 071225 and WO 2020 / 004600. Typically, these methods involve using a specific B4C as a raw material, synthesizing B4CN4 through pressurized nitriding, decarburizing by heating in the atmosphere, adding boric acid or the like, decarburizing and crystallizing in a crystallization furnace, and then crushing and sieving 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 to 30,000; (2) the aromatic vinyl compound monomer is an aromatic vinyl compound having from 8 to 20 carbon atoms, and the content of the aromatic vinyl compound monomer is from 0.1 to 70 mass%; (3) the olefin monomer unit is one or more selected from an α-olefin monomer unit having from 2 to 30 carbon atoms and a cyclic olefin monomer unit having from 7 to 30 carbon atoms, and the content thereof is from 5 to 95 mass%; (4) the aromatic polyene monomer is one or more selected from polyenes having from 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 from 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 (which refers to a monomer that is the basis of the olefin monomer units in the copolymer, but in this specification, the terms "monomer" and "monomer unit" (or "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 from 2 to 20 carbon atoms and cyclic olefin monomers having from 7 to 30 carbon atoms. Examples of α-olefin monomers having from 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. Preferably, the α-olefin monomers are a combination of ethylene and an α-olefin other than ethylene, and most preferably ethylene. In the present copolymer, the content of the α-olefin monomer units is arbitrary, but is preferably from 0 to 70% by mass, more preferably from 0 to 60% by mass, and even more preferably from 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. While such cyclic olefins are characterized by low dielectric properties and high glass transition temperatures, they also have the notable advantage of 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 containing polymerizable vinyl, vinylene, or vinylidene groups 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 mixtures with norbornene, etc., for copolymerization.

[0033] In particular, the above-mentioned DMON and TMDA may be obtained as a mixture with norbornene when produced by the Diels-Alder reaction, and using the mixture as is for polymerization can 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 having such aromatic substituents can impart a higher glass transition temperature (Tg) to the copolymer, and because they exhibit aromaticity, they can 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 can improve the thermal oxidation resistance of the resulting copolymer, as described in JP-A-2005-239975. Norbornenes having these aromatic substituents are specifically described, for example, in JP-A-11-504669 and JP-A-2005-239975.

[0034] The content of the 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 the cyclic olefin monomer units contained in the copolymer varies depending on the type of cyclic olefin. For example, the optimal content 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 the cyclic olefin monomer units, the higher the Tg of the copolymer. The optimal content of the 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 makes it easier to achieve a preferred high glass transition temperature of the copolymer. The preferred glass transition temperature of the copolymer is 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 tangent value 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 has 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 may be preferably from 0.1% by mass to 70% by mass, more preferably from 1% by mass 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, the compatibility with other resin materials, flame retardants, and fillers is improved, the bleed-out of flame retardants is suppressed, and high filler loading is facilitated, 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 groups 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 various ortho-, meta-, and para-divinylbenzenes or mixtures thereof, divinylnaphthalene, divinylanthracene, p-2-propenylstyrene, p-3-butenylstyrene, or other compounds having an aromatic vinyl structure and consisting essentially of carbon and hydrogen and substantially free of oxygen, nitrogen, and halogens. Furthermore, bifunctional aromatic vinyl compounds such as 1,2-bis(vinylphenyl)ethane (abbreviation: BVPE), as described in JP-A-2004-087639, can also be used. Among these, various ortho-, meta-, and para-divinylbenzenes or mixtures thereof are preferably used, and a mixture of meta- and para-divinylbenzene is most preferably used. 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 lower than a certain value improves workability and facilitates impregnation of glass fibers and the like with the varnish, improving embeddability 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. Because 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 temperatures. The vinyl group content derived from aromatic polyene monomer units (divinylbenzene monomer units) per number average molecular weight in the copolymer is determined by the ratio of 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 to ... 1 H-NMR measurement and / or quantitative mode 13 The composition can be determined by comparing the composition obtained 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 of the aromatic vinyl / vinylene group ( 1 H, 13 C) to determine the proportion (a) of divinylbenzene units contained, and the strength of the ethyl groups connected to the benzene ring ( 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 (c) of styrene units 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 each of the contents of (a), (b), and (c) from the ratio (c) of the aliphatic hydrocarbon region. 13 From C), the abundance ratio (e) of ethylene and norbornene units can be determined, and the contents of ethylene, norbornene, styrene, divinylbenzene, and ethylvinylbenzene can be calculated by combining (a), (b), (c), (d), and (e).

[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 the production of the copolymer and the stability during 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, when the copolymer contains cyclic olefin monomer units, or when the content of these units is increased, the thermal conductivity tends to increase when compared to cured products of compositions with boron nitride prepared using the same method and at the same blend ratio. Furthermore, increasing the content of cyclic olefin monomer units as described above 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, measured at 40 GHz and 25°C, and a dielectric dissipation factor of less than 0.0008, preferably less than 0.0006. An olefin-aromatic vinyl compound-aromatic polyene copolymer that satisfies these requirements is preferably a copolymer that contains a cyclic olefin component in the olefin component. In this specification, "curing alone" is defined to mean 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 atoms and hydrogen atoms, based on the mass of the copolymer, under conditions appropriate for the curing agent.

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

[0046] <Composition Comprising a Copolymer and a Specific Boron Nitride Powder> The composition comprising the copolymer of the present invention and a specific boron nitride powder can be cured by itself, but the copolymer of the present invention can also be combined with other materials to form a composition, which can then be cured. Here, the other materials can 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 resin components 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. Of these, hydrocarbon-based elastomers and olefin-aromatic vinyl compound-aromatic polyene copolymers containing no cyclic olefin are more preferred. Among hydrocarbon-based elastomers, conjugated diene polymers are preferred. Among conjugated diene polymers, 1,2-polybutadiene is preferred. The 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 higher dielectric constants and dielectric loss tangents for 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> Hydrocarbon elastomers 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 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 elastomers may be modified, for example, by introducing functional groups with 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 available 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 hydrogenated products thereof may be modified, for example, by introducing functional groups with maleic anhydride or other compounds. Among the 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-Based 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 preferably radically polymerizable functional groups. A vinyl group is preferable as the radically polymerizable functional 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 preferable, one or more of the group consisting of a (meth)acryloyl group and an aromatic vinyl group are more preferable, and an aromatic vinyl group is most preferable. 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 preferable. 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> Aromatic polyene resins include 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 the Same" (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) essentially 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 included in the present composition may be a known curing agent that has been conventionally used for the polymerization or curing of aromatic polyenes or aromatic vinyl compounds. Examples of such curing agents include radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators, with radical polymerization initiators being preferred. Organic peroxides and azo polymerization initiators are preferred, and can be freely selected depending on the application and conditions. Catalogs listing organic peroxides can be downloaded from the NOF Corporation website, for example, https: / / www.nof.co.jp / product-search / family / 1020001. 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 that do not contain oxygen or nitrogen atoms in their structure, i.e., composed only of carbon and hydrogen atoms, such as 2,3-dimethyl-2,3-diphenylbutane, can also be suitably used. When a cured product is produced using such a hydrocarbon-based radical polymerization initiator, a cured product containing no oxygen or nitrogen atoms and having a lower dielectric constant and dielectric dissipation factor can be obtained, 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 the curing agent. Examples of curing agents that utilize a photopolymerization initiator 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. It is also possible to perform crosslinking and curing by thermal polymerization of the raw materials contained in the product without using a curing agent.

[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 polymerization initiator, the curing treatment should be carried out at an appropriate temperature and time, taking into account its half-life. In this case, the conditions can be determined arbitrarily depending on the curing agent, but a temperature range of approximately 50°C to 250°C is generally appropriate.

[0054] <Monomer> The composition of the present invention may contain any amount of monomer, 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 free of monomer. 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 are 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> For the purpose of imparting adhesion to other materials required as an insulating material, 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. Addition of a larger 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, trimethylolpropane tri(meth)acrylate, etc. Maleimides and bismaleimides usable in the present invention are described, for example, in International Publication No. 2016 / 114287 and can be purchased, 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 a multifunctional group (e.g., two or more functional 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, so a solvent with a boiling point of at least a certain level is preferred. A preferred boiling point is 100°C or higher, more preferably 130°C or higher and 300°C or lower, 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 the case of a solvent, the amount used is preferably in the range of 10 to 2,000 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 a drying treatment or the like before the composition is cured.

[0058] <Other Fillers> If necessary, inorganic fillers other than the above-mentioned boron nitride or organic fillers may be added. Known inorganic fillers, such as fused silica or 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, relative to 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 in particular, 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+ (registered trademark) 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 dissipation factor. 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 may result in the thermal conductivity of the final cured product being lower than desired. When these fillers are further added to the specific boron nitride powder, 70 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less of another filler may be added 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 composition contains one or more selected from these fillers, flame retardants, and surface modifiers, and the cured body tends to exhibit impact resistance and toughness even after curing.

[0061] <Flame Retardant> A known flame retardant 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 organic phosphorus-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 tetraoxide, 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-trialyloxy-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. Furthermore, a polyphenylene ether (PPE) resin with a low dielectric constant and excellent flame retardancy may be used in an amount of 30 to 200 parts by mass 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 product such as 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, ultraviolet absorbers, etc., 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 a shape such as a sheet, tube, strip, or pellet by a known molding method for a thermoplastic resin 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. Excluding resins that are liquid at room temperature, when the resin component contains a certain proportion or more of one or more resins selected from the hydrocarbon elastomers, polyether resins, olefin-aromatic vinyl compound-aromatic polyene copolymers that do not contain cyclic olefins, and aromatic polyene resins, the composition is also easily molded into a thermoplastic resin in an uncured state. The thermoplastic compositions described above can be molded into various shapes, such as sheets, at or below the active temperature of the curing agent, utilizing their thermoplasticity. These can then be laminated and combined with semiconductor elements, wiring, or substrates as needed, and then heat-cured and bonded.

[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 component, 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 Article in a 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 been semi-cured (so-called B-stage state). Here, the term "semi-cured state" is defined as a state in which the proportion of gel content as a 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 further contains a curing agent such as a peroxide, which is partially cured and adjusted to a sheet shape (B-stage state). After molding and assembling the device, the composition can be heated under pressure to fully cure. Known methods can be used to partially cure the composition. For example, peroxides with different decomposition temperatures are used in combination, and the mixture 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 mixture is treated for a sufficient time at a temperature at which all of the curing agents are active to fully cure the sheet.

[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 Articles 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 sufficient amount of solvent and / or an appropriate amount of liquid monomer can be used to make the composition into a varnish. 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, so a solvent with a boiling point above a certain level is preferred. A preferred boiling point is approximately 110°C or higher and 300°C or lower 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, for interlayer insulating layers it is generally 10 μm to 200 μm, and for insulating layers 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 a varnish or the like, an extrusion method, an extrusion lamination method, and a coating method.

[0074] <Curing> The resin-filled boron nitride plate can be cured by a known method, taking into consideration the curing conditions (temperature, time, pressure) of the curing agent contained therein. When the curing agent used is a peroxide or azo-based curing agent, the curing conditions can be determined by taking into consideration the half-life temperature and the like disclosed for each curing agent.

[0075] <Cured Product of 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 a high-frequency electrical insulating material, 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 and produce a cured product having the above physical property parameters by referring to the information described in this specification and publicly available 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 in which 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 copper-clad laminate (CCL) board, or a single-layer or multilayer flexible copper-clad laminate (FCCL) 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 include a cured resin-filled boron nitride plate of the present invention. Furthermore, it is useful as an insulating heat dissipation material for multilayer antenna substrates that include RFICs and high-frequency wiring (antenna feedlines) layered below the antenna structure material 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. As the transition metal compound, transition metal compounds containing zirconium, hafnium, titanium, iron, nickel, cobalt, and palladium are preferred. In particular, for copolymerizing cyclic olefin monomers, transition metal compounds containing zirconium, titanium, nickel, iron, and palladium are 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 monomer of an olefin such as an α-olefin or a cyclic olefin, an aromatic vinyl compound, and an aromatic polyene 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)

[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, or an unsubstituted or substituted indenyl group. Y is bonded to A and B and is a methylene group, silylene group, ethylene group, germylene group, or boron residue 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 an additional 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 an additional 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 dialkylamido group having an alkyl substituent having 1 to 6 carbon atoms. M is a transition metal, and may be preferably zirconium, hafnium, or titanium.

[0082] To obtain a copolymer having a relatively low molecular weight and a low viscosity when made into a varnish, preferably, A and B in the above general formula (1) may each independently be a group selected from an unsubstituted or substituted cyclopentadienyl group or an unsubstituted or substituted indenyl group, and 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 having a high aromatic polyene content, i.e., a copolymer having a high number of vinyl groups 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. When a copolymer has a high aromatic polyene monomer unit content, it is possible to increase the crosslink density of the cured product obtained by curing, and for example, a cured product having a storage modulus of 5 MPa or more measured at 280°C can be obtained.

[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 preferably used as the aluminum compound. Alternatively, alkylaluminums such as triisobutylaluminum and triethylaluminum may be used. Furthermore, aluminum compounds and boron compounds may be used together. Examples of such cocatalysts include the cocatalysts and alkylaluminum compounds described in EP 0872492A2, JP 11-130808 A, JP 9-309925 A, WO 00 / 20426 A, EP 0985689A1, and JP 6-184179 A.

[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 of such compounds 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 sometimes referred to 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 atomic 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 a polymerization facility, or may be mixed inside the facility during polymerization.

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

[0087] In a preferred embodiment, a co-catalyst may be used that uses a boron compound as an essential component and an aluminum compound as needed. 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 finally obtained copolymer can be reduced, and the values ​​of the dielectric constant and dielectric loss tangent of the finally obtained uncured copolymer, or the values ​​of the dielectric constant and dielectric loss tangent 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 made less than 2.5 and the dielectric loss tangent can be made 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 (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 elemental 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 satisfy the properties of a dielectric constant of less than 2.5 and a dielectric loss tangent of less than 0.0008, preferably less than 0.0006, particularly at 40 GHz. 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.

[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 scaly 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 titrated with a normal sulfuric acid solution. The content of nitrogen atoms (N) in the boron nitride powder was calculated from the titration results. From the obtained nitrogen atom content, the content of hexagonal boron nitride (hBN) in the boron nitride powder was determined based on 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 nitrogen atoms was 14.006 g / mol. Content of hexagonal boron nitride (hBN) in sample [mass%] = Content of nitrogen atoms (N) [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 laser diffraction scattering particle size distribution analyzer (instrument name: LS-13 320) manufactured by Beckman Coulter. The measurement was carried out without subjecting the boron nitride powder to homogenization. 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. In this case, the refractive index of water was set to 1.33, and the refractive index of the boron nitride powder was set to 1.80.

[0093] <Specific Surface Area of ​​Boron Nitride Powder> The specific surface area of ​​the boron nitride powder was calculated by 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: Cantorsorb) manufactured by Yuasa Ionics Co., Ltd. The measurement was performed after drying and degassing the boron nitride powder at 300°C for 15 minutes.

[0094] <Compression Strength (Crushing Strength) of Agglomerate Particles> The crushing strength of the agglomerate particles was measured in accordance with the description in JIS R 1639-5:2007 "Fine Ceramics - Measurement of Granule Characteristics - Part 5: Single Granule Crushing Strength." The crushing strength σ (unit: [MPa]) was calculated using the dimensionless number α (α = 2.48), which varies depending on the position within the particle, the crushing test force P (unit: [N]), and the particle diameter d (unit: [μm]) of the agglomerate particles being measured, using the formula σ = α × P / (π × d2), where the point at which the cumulative fracture rate of 20 particles was 63.2% was the crushing strength.

[0095] <Orientation Index of Boron Nitride Powder> The orientation index of the boron nitride powder was determined from the results of measurement by 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 (manufactured by Rigaku Corporation, product name: ULTIMA-IV), and a measurement sample was prepared by compacting it at a set pressure M using a powder sample molding machine (manufactured by Amenatec Co., Ltd., product name: PX700). If the surface of the filled material compacted by the molding machine was not smooth, it was smoothed manually before measurement. The measurement sample was irradiated with X-rays and baseline correction was performed, after which the peak intensity ratio of the (002) plane to the (100) plane of boron nitride was calculated, and 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 example.

[0096]

[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 13 C-NMR measurement was performed, and the determination was performed using a known method based on the area intensity of the obtained peaks. The sample was dissolved in heavy 1,1,2,2-tetrachloroethane, and the measurement was performed at 80 to 130°C. In this specification, the copolymer may also be referred to as a "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 Multipore HXL-M φ7.8 × 300 mm (manufactured by Tosoh Corporation) connected in series were used. Column temperature: 40°C. Solvent: THF. Flow rate: 1.0 ml / min. Detector: RI detector.

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

[0101] <Dielectric constant and dielectric loss (dielectric loss tangent)> The dielectric loss tangent was measured at 23°C and 40 GHz using a cavity resonator perturbation method (Agilent Technologies 8722ES network analyzer, Keysight Technologies split cylinder resonator 40 GHz) using a 0.1 mm × 25 mm × 30 mm sample cut out from the sheet. Measurements were made for both the uncured and cured states.

[0102] <Quantification of Metal Content in Copolymer> 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 cocatalyst) was measured as follows. Furthermore, the contents of hafnium, titanium, iron, nickel, cobalt, and palladium were also quantified. Measurements were performed using 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 mixture of hydrochloric acid and water by volume) and ultrapure water were added to the residue, dissolved by heating, and then the volume was adjusted to 5 ml to form the test solution. Quantitative analysis was performed using ICP atomic emission spectrometry (using an Agilent 5110VDV).

[0103] <Measurement of Breakdown Voltage> The cured sheet was cut using a cutter to a length of 50 mm from the edge to prepare a measurement sample. One of the cut-out measurement samples was placed on a copper plate in a measurement jig (manufactured by Onishi Electronics Co., Ltd.), a 40 mm square x 1 mm thick copper plate was placed in the center, and insulating oil (manufactured by 3M, product name: Novec 7200) was filled so that the measurement sample was sufficiently immersed. Next, an electrode was lowered from above the measurement sample, creating a situation in which electricity could be passed between the device and the measurement sample, and 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] <Evaluation of Thermal Conductivity> Measurement of thermal conductivity H (unit: W / (m·K)) of cured sheet: Thermal conductivity H is calculated by multiplying thermal diffusivity A (unit: m 2 / sec), density B (unit: kg / m 3 ), and specific heat capacity C (unit: J / (kg K)) were calculated based on the formula H = A × B × C. The thermal diffusivity A was measured by processing the evaluation sheet into a length of 10 mm, a width of 10 mm, and a thickness of 0.3 mm using a laser flash method. The measurement device used was a xenon flash analyzer (manufactured by NETZSCH, product name: LFA447NanoFlash). 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 co-catalyst 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). Norbornene (75% concentration, toluene solution) manufactured by Maruzen Petrochemical Co., Ltd. was used as the raw material. A small amount of triisobutylaluminum (TIBA) was added beforehand, the mixture was stirred at room temperature, and then distilled and purified 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 thoroughly dried polymerization vessel was first purged with nitrogen, and 1.4 kg of toluene, 0.23 kg of pure norbornene, 3.0 kg of styrene, and 0.60 kg of divinylbenzene (81% divinylbenzene) were charged. Approximately 20 L of dry nitrogen was bubbled through the vessel at an internal temperature of 60°C. The inside of the polymerization vessel was then purged with ethylene gas, and 6 mmol of TIBA (manufactured by Kanto Chemical Co., Inc.) was added and stirred. The internal temperature was stabilized at 80°C, and the internal pressure of the polymerization vessel was increased to 0.1 MPaG (gauge) with nitrogen and stabilized. Then, from a catalyst tank installed above the polymerization vessel, a catalyst solution was added to the polymerization vessel, which had been prepared by adding 210 μmol of tritylium tetrakis(pentafluorophenyl)borate to 100 g of a toluene solution containing 200 μmol of dimethylmethylenebis(cyclopentadienyl)zirconium dichloride (formula (1)) as a catalyst and 2 mmol of TIBA, and stirring the solution, and the catalyst solution was added to the polymerization vessel to initiate polymerization. The polymerization was continued while maintaining the internal temperature at 60°C and the internal pressure at 0.1 MPaG (ethylene pressure), and when the ethylene consumption reached 100 g, 50 g of isopropanol (a polymerization terminator) was added to the polymerization vessel to terminate the polymerization. The obtained polymerization liquid was poured little by little into a sufficiently large amount of a methanol / acetone mixed solution, and the precipitated polymer was recovered by stirring and filtering, and the polymer was thoroughly dried in vacuum at room temperature to obtain an ethylene-norbornene-styrene-divinylbenzene copolymer P-2.

[0107] Formula (1)

[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 (mass of 81% divinylbenzene product) 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 as a polymerization terminator was added to the polymerization vessel to terminate the polymerization. The resulting polymerization solution was poured little by little into a sufficiently large amount of methanol / acetone mixed solution, and the precipitated polymer was recovered by stirring and filtration, and 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 a methanol / acetone mixed solution. The precipitated polymer was stirred and filtered, and dried at room temperature under vacuum for 24 hours to obtain a purified polymer. 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 obtain a 50% by mass toluene solution (varnish).

[0110] <Preparation and Evaluation of Copolymer Monocurd Products> To varnishes containing 50% by mass of each of P-1 to P-3, 0.75% by mass of initiator, relative to the mass of the resin content, was added and dissolved. Perbutyl P was used for P-1, and 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 at 100°C for 3 hours in a vacuum dryer to obtain uncured sheets that were substantially free of solvent. If necessary, multiple uncured sheets were stacked to 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, a Teflon sheet, and a smooth metal plate were then placed on top of that. In the case of 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. In the case of 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 sheet (all measured at 23°C and 40 GHz) were determined. The results are shown in Table 2.

[0111]

[0112] Example 1: Preparation of Composition and Preparation of Cured Sheet P-1 was dissolved in toluene varnish (P-1 concentration 50% by mass) and Perbutyl P was added as a curing agent at a concentration of 0.75% by mass relative to the mass of P-1 (mass of resin component). Furthermore, boron nitride powder BN-1 (manufactured by Denka Company, average particle size 40 μm, thermal conductivity 150 W / m·K) was added as an inorganic filler so that the mass ratio of P-1:BN-1 was 30:70 (volume ratio of P-1:BN-1 was 50:50). The mixture was stirred and kneaded at 1600 rpm for 3 minutes using a Thinky Mixer to prepare a composition. The resulting composition was applied to a Teflon sheet to a thickness of 0.20 mm after drying and curing, and the toluene was air-dried at 60°C until no weight change was observed. This produced 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 in which the mass ratio of P-3:SGPS was 30:70, a uniform composition could not be obtained even when the mixing conditions were changed in various ways, and the subsequent sheet formation and evaluation could not be carried out.

[0116] <Comparative Example 2> The mass ratio of P-3:SGPS in Comparative Example 1 was gradually changed to 30:40 to investigate the blending process, gradually decreasing the mass ratio of SGPS. When this was changed, a uniform moldable composition was obtained. Thereafter, the same procedure as in Example 1 was carried out to obtain a cured sheet.

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

[0118]

Claims

1. A composition comprising 15 to 70 parts by mass of an olefin-aromatic vinyl compound-aromatic polyene copolymer and 85 to 30 parts by mass of boron nitride powder that satisfies all of the following (A) to (C), totaling 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) The 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.

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 to 30,000; (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 unit is 0.1 to 70 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 to 95 mass%; (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 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.

4. The composition according to any one of claims 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.

5. The composition according to any one of claims 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, measured at 40 GHz and 25°C.

6. A cured product of the composition according to any one of claims 1 to 5.

7. The cured product according to claim 6, which has 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.

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

9. A high-frequency transmission circuit comprising the cured product according to any one of claims 6 to 8.

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 product according to any one of claims 6 to 8.

11. A three-dimensional highly integrated circuit packaging package or chiplet comprising the cured body according to any one of claims 6 to 8.

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