WO2025105440A1 - Curable composition, prepreg, metal-clad laminate, printed wiring board, semiconductor package, and molded article - Google Patents

Abstract

Provided are a curable composition, a prepreg, a metal-clad laminate, a printed wiring board, a semiconductor package, and a molded article. The curable composition comprises a compound having a vinylbenzyl group, and has a minimum melt viscosity of 3,000 Pa·s or less, as measured in the range of 40–150 °C, for the curable composition that has been subjected to a thermal history of being heated at 130 °C for 10 minutes.

Description

Curable compositions, prepregs, metal-clad laminates, printed wiring boards, semiconductor packages, and molded articles

This disclosure relates to curable compositions for prepregs, prepregs, metal-clad laminates, printed wiring boards, semiconductor packages, and molded products.

Metal-clad laminates, such as copper-clad laminates, prepregs that can be used with metal-clad laminates, and semiconductor packages that use metal-clad laminates are used in a wide variety of electronic devices, including mobile communication devices such as smartphones, base station equipment, servers, routers, large servers, and other network infrastructure devices, as well as large computers, personal computers, and industrial computers. They are also used in electronic devices installed in home appliances, automobiles, etc.

When processing huge amounts of data at high speed in electronic devices, circuit board materials with low transmission loss in the high frequency range are required. Resins with low dielectric constants and low dielectric tangents are used as circuit board materials to provide circuit boards with low transmission loss, but recent developments in communication technology have created a demand for the development of resins with even lower dielectric constants and dielectric tangents.

Patent Document 1 discloses a compound having an indene ring structure with a vinylbenzyl group introduced therein as a curable vinylbenzyl compound that can be cured to produce a cured product with excellent dielectric properties, high heat resistance, and low water absorption.

JP 2003-277440 A

One of the objectives of this disclosure is to provide a curable composition, a prepreg, a metal-clad laminate, a printed wiring board, a semiconductor package, and a molded product that exhibit excellent long-term heat deterioration resistance of the cured product.

The present disclosure includes the following embodiments. The present disclosure is not limited to the following embodiments.
One embodiment relates to a curable composition comprising a compound having a vinylbenzyl group, wherein the curable composition has a thermal history of being heated at 130°C for 10 minutes and has a minimum melt viscosity of 3,000 Pa s or less as measured in the range of 40 to 150°C.

This disclosure makes it possible to provide curable compositions, prepregs, metal-clad laminates, printed wiring boards, semiconductor packages, and molded products that exhibit excellent long-term heat deterioration resistance in the cured products.

The following describes in detail the embodiments of the present disclosure. The present disclosure is not limited to the following embodiments.

In the present disclosure, a numerical range indicated using "to" indicates a range including the numerical values described before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper limit or lower limit of a certain numerical range may be replaced with the upper limit or lower limit of another numerical range. In addition, the upper limit or lower limit of a numerical range described in the present disclosure may be replaced with a value shown in an example.
In the present disclosure, unless otherwise specified, each component may contain one or more corresponding substances.
In the present disclosure, when a plurality of substances corresponding to each component are present in the curable composition, the content of each component in the curable composition means the total amount of the plurality of substances present in the curable composition, unless otherwise specified.

In this disclosure, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values measured using the following procedure. The weight average molecular weight and number average molecular weight are converted from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve is approximated by a cubic equation using a set of five standard polystyrene samples (PStQuick MP-H, PStQuick B [product name by Tosoh Corporation]). The GPC conditions are shown below.

Apparatus: High-speed GPC apparatus "HLC-8320GPC" (product name, Tosoh Corporation)
Detector: Ultraviolet absorption detector "UV-8320" (product name, Tosoh Corporation)
Columns: Guard column: TSKgel guardcolumn Super (HZ)-M+, column: TSKgel SuperMultipore HZ-M (2 columns), reference column: TSKgel SuperH-RC (2 columns) (all product names of Tosoh Corporation)
Column size: 4.6 x 20 mm (guard column), 4.6 x 150 mm (column), 6.0 x 150 mm (reference column)
Eluent: tetrahydrofuran Sample concentration: 10 mg/1 mL
Injection volume: 20 μL or 2 μL
Flow rate: 0.35mL/min Measurement temperature: 40℃

The curable composition according to one embodiment of the present disclosure is a curable composition that contains a compound having a vinylbenzyl group, and has a minimum melt viscosity of 3,000 Pa·s or less measured in the range of 40 to 150°C in a curable composition that has a thermal history of being heated at 130°C for 10 minutes. A curable composition having such characteristics exhibits the effect of excellent long-term heat deterioration resistance of the cured product. In the present disclosure, the long-term heat deterioration resistance of the cured product refers to the ability to maintain mechanical properties and the like, without deterioration even when the cured product is exposed to high temperature conditions for a long period of time, in applications such as prepregs, fiber-reinforced composite materials, and molding materials, in which the curable composition is impregnated into a fiber substrate or filled into a mold.

Without being bound by any particular theory, it is believed that when a curable composition containing a compound having a vinylbenzyl group (hereinafter sometimes referred to as "compound A") is heated at 130°C for 10 minutes, most or all of the volatile components such as the solvent evaporate, and some of the polymerizable groups of the vinylbenzyl group and optional components polymerize, resulting in a so-called B-staged state. When the minimum melt viscosity measured for this B-staged product is 3,000 Pa·s or less, the curable composition has excellent impregnation or wettability into fiber substrates, or excellent filling ability in a mold, and it is possible to obtain a cured product with low gas permeability. As a result, it is believed that the thermal oxidative decomposition of the cured product under high temperature conditions is suppressed, and an effect of excellent long-term heat deterioration resistance is obtained.

The present disclosure also provides a curable composition having excellent long-term heat deterioration resistance of the cured product, and as a secondary effect, provides a method for determining, by a simpler operation, whether or not the composition can be a curable composition having excellent long-term heat resistance of the cured product. Specifically, as one of the guidelines for determining whether or not the composition can be a curable composition having excellent long-term heat resistance of the cured product, the minimum melt viscosity in the range of 40 to 150°C of a curable composition having a thermal history of being heated at 130°C for 10 minutes is measured, and a determination based on the value becomes possible, which enables more efficient development compared to conventional evaluation tests in which a cured product is stored under high-temperature conditions for a long period of time.
That is, as one embodiment, the present disclosure provides a method for evaluating a curable composition, in which the long-term heat resistance of a cured product is evaluated based on the value of the minimum melt viscosity measured in the range of 40 to 150°C for a curable composition having a thermal history of being heated at 130°C for 10 minutes.

[Minimum melt viscosity of curable composition]
In one embodiment, the minimum melt viscosity of the curable composition is a value measured for a curable composition having a thermal history of being heated at 130° C. for 10 minutes. The method of heating at 130° C. for 10 minutes is not particularly limited, and examples thereof include a method of holding the composition in a thermostatic machine such as an oven. The heating temperature setting may have a fluctuation of ±2° C. in part of the heating process. In addition, the heating time setting may have an error of ±10 seconds.

The state of the curable composition during heating is not particularly limited, and examples of the method include a method of applying the curable composition onto a substrate, a method of putting the curable composition into a container such as a mold or a petri dish, and a method of impregnating a fiber substrate into the shape of a prepreg. Examples of the substrate include a metal plate, a metal film, a resin plate, and a resin film. Examples of the fiber substrate include glass cloth and carbon fiber. The film thickness when applying the curable composition onto the substrate and the liquid level when putting it into a container are not particularly limited, but in order to dry the coating uniformly and reduce the measurement error of the minimum melt viscosity, a range of 50 to 90 μm is preferable. In addition, the thickness of the prepreg is not particularly limited, but in order to reduce the measurement error of the minimum melt viscosity, the film thickness of the resin applied to one side is preferably in the range of 50 to 90 μm. In this case, the thickness of the fiber substrate is preferably in the range of 10 to 100 μm, and the thickness of the entire prepreg is preferably in the range of 100 to 200 μm.

The minimum melt viscosity can be measured with a measuring device such as a rheometer. When measuring the minimum melt viscosity, the curable composition having a thermal history of being heated at 130°C for 10 minutes can be processed into a shape suitable for the measuring device, if necessary, and used. For example, if the sample shape suitable for the measuring device is tablet-shaped, the curable composition having a thermal history can be crushed once and remolded into tablets for use. In order to reduce measurement errors of the minimum melt viscosity, it is preferable not to perform a heating treatment at 100°C or higher during molding.

The minimum melt viscosity is measured in the range of 40 to 150° C. The heating rate is preferably in the range of 2 to 3° C./min. Regarding the measurement temperature range and heating rate, errors due to the accuracy of the measuring device are permissible. As an example of the measuring device and measuring conditions for the minimum melt viscosity, the conditions used in the examples are described below.
Measuring equipment (rheometer): "DHR-20" manufactured by TA Instruments Japan Co., Ltd.
Temperature range and heating conditions: 40 to 150°C, 3°C/min. Sample shape: tablet shape with a thickness of 1.0 to 1.5 mm (approximately 1.2 mm in the example) and a diameter of 20 mm

When the minimum melt viscosity of the curable composition measured in this manner is 3,000 Pa·s or less, the cured product has excellent long-term heat deterioration resistance. The specific reasons and mechanisms are as described above. The minimum melt viscosity is preferably 2,500 Pa·s or less, more preferably 2,000 Pa·s or less, and particularly preferably 1,500 Pa·s or less. The minimum melt viscosity may be 800 Pa·s or more, or may be 1,000 Pa·s or more. The minimum melt viscosity measured in the range of 40 to 150°C for a curable composition having a thermal history of being heated at 130°C for 10 minutes is preferably in the range of 800 to 3,000 Pa·s, for example.

The curable composition preferably has a melt viscosity of 5,000 Pa·s or more at 60°C when the melt viscosity is measured in the range of 40 to 150°C in a curable composition having a thermal history of being heated at 130°C for 10 minutes. By satisfying such conditions, the fluidity under low temperature conditions is not excessively high, resulting in a curable composition with excellent moldability. The melt viscosity at 60°C may be 6,000 Pa·s or more, or may be 7,000 Pa·s or more. In addition, the melt viscosity at 60°C may be 10,000 Pa·s or less, or may be 9,000 Pa·s or less.

The curable composition may have a ratio (V 60 )/(V _min ) of the melt viscosity value at 60° C. when the melt viscosity is measured in the range of 40 to 150° C. to the minimum melt viscosity value (V _min ) measured in the range of ₄₀ to 150° C. in a curable composition having a thermal history of being heated at ₃₀ ° C. for 10 minutes, in the range of 3 to 10. By satisfying such conditions, a curable composition having even better long-term heat deterioration resistance of the cured product can be obtained.

[Curable composition]
In one embodiment, the curable composition includes a compound having a vinylbenzyl group (compound A). Compound A is one of the excellent materials in terms of excellent dielectric properties and heat resistance in the cured product. Compound A may have one or more vinylbenzyl groups. Compound A may be used alone or in combination of two or more types.

Specific examples of compound A include a compound represented by the following general formula (1) (hereinafter, this may be referred to as "compound A1"), a prepolymer using compound A1 (hereinafter, this may be referred to as "prepolymer A2"), a compound represented by the following general formula (2-1) (hereinafter, this may be referred to as "compound A3"), a resin containing two or more compounds having different structures among the compounds represented by the following general formula (2-2), including at least one compound in which m is an integer of 1 or more and at least one compound in which n is an integer of 1 or more (hereinafter, this may be referred to as "resin A3"), a compound represented by the following general formula (3) (hereinafter, this may be referred to as "compound A4"), and a vinylbenzyl-modified phenolic resin (hereinafter, this may be referred to as "resin A5"). Note that these are merely some of the specific examples of compound A, and compounds that can be used as compound A in this disclosure are not limited to these.

[In general formula (1), Ar ¹ represents an aromatic hydrocarbon structure which may have a substituent, and 1 is an integer of 1 or 2 or more.]

[In the general formula (2-1), ^Ar2 represents an aromatic hydrocarbon structure which may have a substituent, m is an integer of 1 or 2 or more, ^Ar3 represents an aryl group other than a styryl group, and n is an integer of 1 or 2 or more.]

[In the general formula (2-2), ^Ar2 represents an aromatic hydrocarbon structure which may have a substituent, m is an integer of 0 or 1 or more, ^Ar3 represents an aryl group other than a styryl group, and n is an integer of 0 or 1 or more.]

[In the general formula (3), R ¹ is an alkylene group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or a vinylbenzyl group.]

　In the compound represented by the above general formula (1) (compound A1), the vinylbenzyl group contained in compound A1 may be any of o-vinylbenzyl group, m-vinylbenzyl group, and p-vinylbenzyl group. Among these, p-vinylbenzyl group is preferable. The proportion of p-vinylbenzyl groups in all vinylbenzyl groups contained in the vinylbenzyl compound may be 10% or more, 20% or more, or 30% or more. It may also be 100% or less, 80% or less, or 70% or less. For example, it may be in the range of 10 to 100%. When the proportion of p-vinylbenzyl groups is less than 100%, the remaining vinylbenzyl groups may be m-vinylbenzyl groups.

Ar ¹ in the general formula (1) is an aromatic hydrocarbon structure which may have a substituent. Specific examples of aromatic hydrocarbons include benzene, indene, naphthalene, fluorene, anthracene, phenanthrene, tetracene, chrysene, pyrene, triphenylene, etc. Among them, benzene, indene, naphthalene, and fluorene are preferred, indene and fluorene are more preferred, and indene is particularly preferred.

When Ar ¹ has a substituent, specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and t-butyl; unsaturated bond-containing groups such as vinyl and allyl; aryl groups such as phenyl, tolyl, xylyl, mesityl, and naphthyl; aryloxy groups such as phenyloxy, tolyloxy, xylyloxy, mesityloxy, and naphthyloxy; aralkyl groups such as benzyl, α-methylbenzyl, triphenylmethyl, and naphthylmethyl; and aralkyloxy groups such as benzyloxy. Ar ¹ may not have a substituent.

In general formula (1), l is an integer of 1 or more. The preferred number of l varies depending on the type of aromatic hydrocarbon structure represented by Ar ¹ , but when Ar ¹ is an indene ring structure, l is preferably an integer of 1 to 3. When Ar ¹ is an indene ring structure, examples of compound A1 include compounds represented by the following general formula (4).

[In the general formula (4), R ³ , R ⁴ and R ⁵ are a vinylbenzyl group or a hydrogen atom, and at least one of R ³ , R ⁴ and R ⁵ is a vinylbenzyl group.]

When a compound represented by general formula (4) is used as compound A1, one type may be used alone, or multiple types of compounds having different numbers of vinylbenzyl groups in one molecule may be used. In the latter case, since the compound has excellent curing properties, the average number of vinylbenzyl groups in one molecule is preferably in the range of 1.0 to 3.0, and more preferably in the range of 1.6 to 2.5.

Compound A1 is a compound specified by its molecular structure, and its production method is not particularly limited. An example of the method for producing compound A1 is a method of reacting an aromatic compound corresponding to the Ar ¹ group with a styrene having a halogenated methyl group in the presence of a basic compound.

Examples of styrenes having a halogenated methyl group include o-chloromethylstyrene, m-chloromethylstyrene, and p-chloromethylstyrene. One type of styrene having a halogenated methyl group may be used alone, or two or more types may be used in combination. Examples of basic compounds include alkali metal hydroxides and alkali metal alkoxides. One type of basic compound may be used alone, or two or more types may be used in combination.

A phase transfer catalyst may be used in the above reaction. Examples of phase transfer catalysts include quaternary ammonium salts such as tetra-n-butylammonium chloride, tetra-n-butylammonium bromide (tetra-n-butylammonium bromide), tetraethylammonium chloride, tetraethylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, benzyltributylammonium chloride, benzyltributylammonium bromide, benzyldimethyltetradecylammonium chloride, tricaprylmethylammonium chloride, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, trioctylmethylammonium chloride, and tetra-n-butylammonium hydrogen sulfate; and quaternary phosphonium salts such as tetra-n-butylphosphonium chloride, tetra-n-butylphosphonium bromide, tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, benzyltriphenylphosphonium chloride, and benzyltriphenylphosphonium bromide.

The reaction between the aromatic compound corresponding to the Ar ¹ group and the styrene having a halogenated methyl group can be carried out by solution polymerization. The reaction may be carried out, for example, under heating and stirring conditions. If necessary, a polymerization inhibitor may be added to the reaction system. Examples of the polymerization inhibitor include phenothiazine, 3,7-dioctylphenothiazine, 3,7-dicumylphenothiazine, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and bis(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl)sebacate. If necessary, the obtained product may be purified by a known method such as concentration, reprecipitation, or washing.

The obtained product may be a single compound or a mixture of two or more compounds. When it is a mixture of two or more compounds, it may contain a compound in which l in the above general formula (1) is 0, and the mixture may be used as is in the curable composition. In that case, since the curable composition has excellent curability, the average number of vinylbenzyl groups in one molecule in the mixture is preferably in the range of 1.0 to 3.0, and more preferably in the range of 1.6 to 2.5.

In this disclosure, the term "prepolymer" used in the present disclosure for the prepolymer (prepolymer A2) using compound A1 refers to a polymer in which some of the polymerizable reactive groups of the monomer, the raw material of the polymer, remain. Therefore, prepolymer A2 has unreacted vinylbenzyl groups derived from compound A1 and exhibits radical polymerization properties.

Prepolymer A2 may be made by using compound A1 together with other monomers other than compound A1. The proportion of compound A1 in the total monomers constituting prepolymer A2 is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and particularly preferably 90 to 100% by mass.

The method for producing prepolymer A2 is not particularly limited, and it can be produced by a method in which a monomer containing compound A1 is polymerized by a general method. One example is radical polymerization.

The polymerization initiator used in the radical polymerization is not particularly limited, and examples thereof include azo-based polymerization initiators and organic peroxide-based polymerization initiators. Examples of azo-based polymerization initiators include 2,2'-azobis(2,4,4-trimethylpentane), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 1,1'-azobis(cyclohexane-1-carbonitrile), and dimethyl Examples of the azobis(1-cyclohexanecarboxylate), azobis(isobutyronitrile), azobis(2-methylpropanenitrile), azobis(2-methylbutyronitrile), azobis(4-methoxy-2,4-dimethylvaleronitrile), azobis(2,4-dimethylvaleronitrile), azobis(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 4-cyanopentanoate), and the like. Examples of organic peroxide polymerization initiators include dicumyl peroxide, dibenzoyl peroxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, bis(tert-butylperoxyisopropyl)benzene, and tert-butyl hydroperoxide.

The radical polymerization initiator may be used alone or in combination of two or more types. The amount of radical polymerization initiator used can be adjusted appropriately depending on the desired degree of polymerization, etc., but in order to facilitate reaction control, it is preferable to use a radical polymerization initiator in the range of 0.01 to 5 parts by mass per 100 parts by mass of the total of the monomers, which are the reaction raw materials.

The polymerization reaction of prepolymer A2 may be carried out in a solvent. Examples of the solvent that may be used include toluene and xylene. These may be used alone or in the form of a mixed solvent of two or more types. There are no particular limitations on the amount of solvent used, but a range of 30 to 500 parts by mass per 100 parts by mass of the monomers, which are the raw materials for the reaction, is preferred in terms of making it easier to control the reaction.

The weight average molecular weight (Mw) of prepolymer A2 is not particularly limited, but is preferably in the range of 50,000 to 400,000, for example, from the viewpoint of ease of production and ease of handling of the curable composition for prepreg. The weight average molecular weight (Mw) of prepolymer A2 may be 70,000 or more, 80,000 or more, or 100,000 or more. It may also be 300,000 or less, 250,000 or less, or 200,000 or less.

　With respect to a compound (compound A3) represented by the above general formula (2-1) and a resin (resin A3) containing two or more compounds having different structures from each other among the compounds represented by general formula (2-2), and containing at least one compound in which m is an integer of 1 or more and at least one compound in which n is an integer of 1 or more, the vinylbenzyl group contained in compound A3 and the vinylbenzyl group contained in resin A3 may be any of o-vinylbenzyl group, m-vinylbenzyl group, and p-vinylbenzyl group. Among these, p-vinylbenzyl group is preferred. The proportion of p-vinylbenzyl groups in all vinylbenzyl groups contained in the vinylbenzyl compound may be 10 mol% or more, 20 mol% or more, or 30 mol% or more. It may also be 100 mol% or less, 80 mol% or less, or 70 mol% or less. For example, it may be in the range of 10 to 100 mol%. When the proportion of p-vinylbenzyl groups is less than 100 mol%, the remaining vinylbenzyl groups may be m-vinylbenzyl groups.

In the general formula (2-1) and the general formula (2-2), ^Ar3 is an aryl group other than a styryl group. Specific examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group.

^Ar2 in the general formula (2-1) and the general formula (2-2) is an aromatic hydrocarbon structure which may have a substituent. Specific examples of aromatic hydrocarbons include benzene, indene, naphthalene, fluorene, anthracene, phenanthrene, tetracene, chrysene, pyrene, triphenylene, and the like. Among them, benzene, indene, naphthalene, and fluorene are preferable, indene and fluorene are more preferable, and indene is particularly preferable.

When ^Ar2 has a substituent, specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and t-butyl; unsaturated bond-containing groups such as vinyl and allyl; aryl groups such as phenyl, tolyl, xylyl, mesityl, and naphthyl; and aryloxy groups such as phenyloxy, tolyloxy, xylyloxy, mesityloxy, and naphthyloxy. ^Ar2 may have no substituent.

Regarding compound A3, in general formula (2-1), m is an integer of 1 or 2 or more, and n is an integer of 1 or 2 or more. The preferred numbers of m and n vary depending on the type of aromatic hydrocarbon structure represented by Ar ² , but when Ar ² is an indene ring structure, it is preferred that m and n are each an integer of 1 to 3. Furthermore, it is more preferred that the sum of m and n is 2 or 3. When Ar ² is an indene ring structure, examples of compound B1 include compounds represented by the following general formula (5-1), and the like.

[In the general formula (5-1), R ⁶ , R ⁷ and R ⁸ are either a vinylbenzyl group, an arylmethyl group or a hydrogen atom. At least one of R ⁶ , R ⁷ and R ⁸ is a vinylbenzyl group, and at least one is an arylmethyl group.]

When a compound represented by general formula (5-1) is used as compound A3, one type may be used alone, or multiple types of compounds with different molecular structures may be used.

Regarding the resin A3, in the general formula (2-2), m is 0 or an integer of 1 or more, and n is 0 or an integer of 1 or more. The preferred numbers of m and n vary depending on the type of aromatic hydrocarbon structure represented by Ar ² , but when Ar ² is an indene ring structure, it is preferable that m and n are each 0 or an integer of 1 to 3. Furthermore, the average value of the sum of m and n is more preferably in the range of 1.5 to 3. When Ar ² is an indene ring structure, the resin A3 may be, for example, a resin containing two or more compounds having different structures among the compounds represented by the following general formula (5-2), in which at least one of R ⁶ , R ⁷ and R ⁸ present in the resin is a vinylbenzyl group, and at least one of R ⁶ , R ⁷ and R ⁸ present in the resin is an arylmethyl group other than a vinylbenzyl group.

[In general formula (5-2), R ⁶ , R ⁷ and R ⁸ are either a vinylbenzyl group, an arylmethyl group or a hydrogen atom. At least one of R ⁶ , R ⁷ and R ⁸ present in the resin is a vinylbenzyl group, and at least one of R ⁶ , R ⁷ and R ⁸ present in the resin is an arylmethyl group other than a vinylbenzyl group.]

Resin A3 may include at ^least one of the ^following : a compound in which one of R ⁶ , R ⁷ and R ⁸ is a vinylbenzyl group, one is an arylmethyl group, and one is a hydrogen atom; a compound in which ^two of R ⁶ , R ⁷ and R ⁸ are vinylbenzyl groups and one is an arylmethyl group; a compound in which one of R ⁶ , R ⁷ and R ⁸ is a vinylbenzyl group and two are arylmethyl groups; a compound in which one to three of R 6 , R ⁷ and R ⁸ are vinylbenzyl groups and the others are hydrogen atoms; a compound in which one to three of R 6 , R ⁷ and R ⁸ are arylmethyl groups and the others are hydrogen atoms; and a compound in which R ⁶ , R ⁷ and R 8 are all hydrogen atoms. In a compound having a plurality of arylmethyl groups in one molecule, the arylmethyl groups may all be different, or some or all may be the same.

Compound A3 and resin A3 are compounds that are specified by their molecular structures, and their manufacturing methods are not particularly limited. One example of a method for manufacturing compound A3 or resin A3 is, for example, a method in which an aromatic compound corresponding to ^Ar2 group, styrene having a halogenated methyl group, and an aromatic compound having a halogenated methyl group corresponding to ^Ar3 group are reacted in the presence of a basic compound. The details of the reaction conditions are the same as those described as the manufacturing method of compound A1.

Examples of styrenes having a halogenated methyl group include o-chloromethylstyrene, m-chloromethylstyrene, and p-chloromethylstyrene. The styrenes having a halogenated methyl group may be used alone or in combination of two or more. Examples of aromatic compounds having a halogenated methyl group corresponding to the Ar ³ group include α-chlorotoluene and α-chloro-p-xylene. The aromatic compounds having a halogenated methyl group may be used alone or in combination of two or more. Examples of basic compounds include alkali metal hydroxides and alkali metal alkoxides. The basic compounds may be used alone or in combination of two or more.

With regard to compound A3, the obtained product may be a single compound or a mixture of two or more compounds. When it is a mixture of two or more compounds, it may contain a compound in which either one or both of m and n in the above general formula (2-1) are 0, and the mixture may be used as it is in the curable composition.

For resin A3, the reaction product may be purified, if necessary, by known methods such as concentration, reprecipitation, washing, etc.

In the compound represented by the above general formula (3) (compound A4), the vinylbenzyl group in compound B4 may be any of o-vinylbenzyl, m-vinylbenzyl, and p-vinylbenzyl groups. Among these, p-vinylbenzyl groups are preferred. The proportion of p-vinylbenzyl groups in all vinylbenzyl groups in the vinylbenzyl compound may be 10% or more, 20% or more, or 30% or more. It may also be 100% or less, 80% or less, or 70% or less. For example, it may be in the range of 10 to 100%. When the proportion of p-vinylbenzyl groups is less than 100%, the remaining vinylbenzyl groups may be m-vinylbenzyl groups.

In the general formula (3), R ¹ is an alkylene group having 1 to 10 carbon atoms. Specific examples of the alkylene group include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, and a 1,6-hexamethylene group.

Regarding the vinylbenzyl-modified phenolic resin (resin A5), resin A5 is specifically a resin in which the phenolic hydroxyl groups of various phenolic hydroxyl group-containing resins have been vinylbenzyl-etherified. The vinylbenzyl group in resin B5 may be any of o-vinylbenzyl, m-vinylbenzyl, and p-vinylbenzyl groups. Among these, p-vinylbenzyl groups are preferred. The proportion of p-vinylbenzyl groups in the total vinylbenzyl groups in the vinylbenzyl compound may be 10 mol% or more, 20 mol% or more, or 30 mol% or more. It may also be 100 mol% or less, 80 mol% or less, or 70 mol% or less. When the proportion of p-vinylbenzyl groups is less than 100 mol%, the remaining vinylbenzyl groups may be m-vinylbenzyl groups.

The weight average molecular weight (Mw) of Resin A5 is not particularly limited, but from the viewpoint of ease of handling, it is preferably 300 or more, more preferably 500 or more, and particularly preferably 1,000 or more. It is also preferably 50,000 or less, more preferably 30,000 or less, and particularly preferably 10,000. The weight average molecular weight (Mw) of Resin A5 may be, for example, in the range of 300 to 50,000.

Examples of resin A5 include those represented by the following general formula (6):

[In general formula (6), each Z is independently a divalent hydrocarbon group. p is an integer of 1 or more.]

　Z in general formula (6) is independently a divalent hydrocarbon group. Examples of divalent hydrocarbon groups include alkylene groups having 1 to 5 carbon atoms, alkylidene groups having 2 to 5 carbon atoms, divalent alicyclic hydrocarbon groups having 5 to 12 carbon atoms, arylene groups having 6 to 12 carbon atoms, and divalent groups combining these. Examples of alkylene groups having 1 to 5 carbon atoms include methylene, 1,2-dimethylene, 1,3-trimethylene, 1,4-tetramethylene, and 1,5-pentamethylene. Examples of alkylidene groups having 2 to 5 carbon atoms include ethylidene, propylidene, isopropylidene, butylidene, isobutylidene, pentylidene, and isopentylidene. Examples of divalent alicyclic hydrocarbon groups having 5 to 12 carbon atoms include divalent groups that are generated by removing two hydrogen atoms bonded to two different carbon atoms from alicyclic hydrocarbon compounds such as norbornane, decalin, bicycloundecane, and saturated dicyclopentadiene. Examples of arylene groups having 6 to 12 carbon atoms include phenylene groups, naphthylene groups, and biphenylene groups.

Z is preferably a divalent group resulting from the loss of two hydrogen atoms bonded to two different carbon atoms in a saturated dicyclopentadiene, or a group combining an alkylene group having 1 to 5 carbon atoms and an arylene group having 6 to 12 carbon atoms. An example of a group combining an alkylene group having 1 to 5 carbon atoms and an arylene group having 6 to 12 carbon atoms is the group represented by the following general formula (7).

[In general formula (7), R ⁹ is independently an alkylene group having 1 to 5 carbon atoms. Ar ⁴ is an arylene group having 6 to 12 carbon atoms.]

Among the above-mentioned alkylene groups having 1 to 5 carbon atoms represented by R ⁹ in general formula (7), a methylene group is preferable. Among the above-mentioned arylene groups having 6 to 12 carbon atoms represented by Ar ⁴ , a phenylene group or a biphenylene group is preferable. Furthermore, the phenylene group is preferably a 1,4-phenylene group, and the biphenylene group is preferably a 4,4'-biphenylene group.

In general formula (6), p is an integer of 1 or more. p may be an integer from 1 to 50, an integer from 1 to 30, or an integer from 1 to 20.

Resin A5 may be produced by any method, and the method of production is not particularly limited. As an example, it can be produced by reacting a base phenolic resin with a vinyl benzylating agent such as chloromethylstyrene in the presence of a basic compound. The details of the reaction conditions are the same as those described as the method of producing compound A1.

Among the compounds A, prepolymer A2 is preferred because it produces a curable composition that exhibits excellent long-term heat deterioration resistance in the cured product.

The ratio of prepolymer A2 to the total compound A may be 30% by mass or more, 50% by mass or more, or 80% by mass or more. It may also be 100% by mass or less, 90% by mass or less, or 80% by mass or less.

The curable composition may contain a compound having a radical polymerizable group other than compound A (hereinafter, this may be referred to as "compound B"). Examples of compound B include a compound having a maleimide group, a polyphenylene ether compound having a radical polymerizable group, styrene, divinylbenzene, triallyl isocyanurate, etc.

Examples of compounds having a maleimide group include compounds having one or more N-substituted maleimide groups and derivatives thereof. Compounds having a maleimide group may be used alone or in combination of two or more types.

Examples of compounds having one or more N-substituted maleimide groups include aromatic maleimide compounds, which are compounds having an N-substituted maleimide group directly bonded to an aromatic ring; aromatic bismaleimide compounds, which are compounds having two N-substituted maleimide groups directly bonded to an aromatic ring; aromatic polymaleimide compounds, which are compounds having three or more N-substituted maleimide groups directly bonded to an aromatic ring; and aliphatic maleimide compounds, which are compounds having an N-substituted maleimide group directly bonded to an aliphatic hydrocarbon.

Specific examples of compounds having one or more N-substituted maleimide groups include N,N'-ethylene bismaleimide, N,N'-hexamethylene bismaleimide, N,N'-(1,3-phenylene) bismaleimide, N,N'-[1,3-(2-methylphenylene)] bismaleimide, N,N'-[1,3-(4-methylphenylene)] bismaleimide, N,N'-(1,4-phenylene) bismaleimide, bis(4-maleimidophenyl)methane, bis(3-methyl-4-maleimidophenyl)methane, and bis(4-maleimidophenyl)methane. 4-maleimidophenyl)methane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, bis(4-maleimidophenyl)ether, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl)sulfide, bis(4-maleimidophenyl)ketone, bis(4-maleimidocyclohexyl)methane, 1,4-bis(4-maleimidophenyl)cyclohexane, 1,4-bis(maleimidomethyl)cyclohexane, 1,4-bis(maleimide methyl)benzene, 1,3-bis(4-maleimidophenoxy)benzene, 1,3-bis(3-maleimidophenoxy)benzene, bis[4-(3-maleimidophenoxy)phenyl]methane, bis[4-(4-maleimidophenoxy)phenyl]methane, 1,1-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,1-bis[4-(4-maleimidophenoxy)phenyl]ethane, 1,2-bis[4-(3-maleimidophenoxy)phenyl]ethane, 1,2 -bis[4-(4-maleimidophenoxy)phenyl]ethane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(4-maleimidophenoxy)phenyl]butane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2, 2-bis[4-(4-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4-bis(3-maleimidophenoxy)biphenyl, 4,4-bis(4-maleimidophenoxy)biphenyl, bis[4-(3-maleimidophenoxy)phenyl]ketone, bis[4-(4-maleimidophenoxy)phenyl]ketone, bis(4-maleimidophenyl)disulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfide, bis[ 4-(4-maleimidophenoxy)phenyl]sulfide, bis[4-(3-maleimidophenoxy)phenyl]sulfoxide, bis[4-(4-maleimidophenoxy)phenyl]sulfoxide, bis[4-(3-maleimidophenoxy)phenyl]sulfone, bis[4-(4-maleimidophenoxy)phenyl]sulfone, bis[4-(3-maleimidophenoxy)phenyl]ether, bis[4-(4-maleimidophenoxy)phenyl]ether, 1,4-bis[4- (4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3- Examples include bis[4-(4-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,4-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(3-maleimidophenoxy)-3,5-dimethyl-α,α-dimethylbenzyl]benzene, polyphenylmethane maleimide, aromatic bismaleimide compounds having an indane skeleton, and biphenylaralkyl-type maleimide compounds.

An example of a derivative of a compound having one or more N-substituted maleimide groups is an aminomaleimide compound that contains a structural unit derived from the compound having one or more N-substituted maleimide groups described above and a structural unit derived from a diamine compound.

The total proportion of compound A in all compounds having a radical polymerizable group in the curable composition may be 50% by mass or more, 70% by mass or more, or 80% by mass or more. It may also be 100% by mass or less, 90% by mass or less, or 70% by mass or less.

The curable composition may contain other components in addition to compounds A and B, as necessary. Examples of other components include thermosetting compounds other than compounds A and B, elastomers, compounds having a phenolic hydroxyl group (excluding those having a radically polymerizable group), fillers, curing accelerators, flame retardants, heat stabilizers, antistatic agents, UV absorbers, pigments, colorants, lubricants, solvents, etc. Each of the other components may be used alone or in combination of two or more types.

Other thermosetting compounds include, for example, epoxy resins, phenolic resins, cyanate resins, benzoxazine resins, oxetane resins, amino resins, silicone resins, triazine resins, and melamine resins. When other thermosetting compounds are used, the ratio of compound A to the total mass of the curable components in the curable composition may be 30 mass% or more, 50 mass% or more, or 80 mass% or more. It may also be 100 mass% or less, 90 mass% or less, or 80 mass% or less. The ratio of compound B to the total mass of the curable components in the curable composition may be, for example, in the range of 30 to 100 mass%. The curable components in the curable composition more specifically refer to compounds A, B, and other thermosetting compounds.

Examples of the elastomer include polyether-based elastomers, styrene-based elastomers, conjugated diene-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. One type of elastomer may be used alone, or two or more types may be used in combination.

The weight average molecular weight (Mw) of the elastomer is not particularly limited, and may be, for example, 100,000 or less, 60,000 or less, or 30,000 or less. It may also be 1,000 or more, 3,000 or more, or 5,000 or more. The weight average molecular weight (Mw) of the elastomer may be, for example, in the range of 1,000 to 100,000.

Among the elastomers, styrene-based elastomers include copolymers of styrene and other polymerizable compounds. Examples of other polymerizable compounds that can be copolymerized with styrene include α-olefin compounds, cyclic olefin compounds, aromatic monovinyl compounds other than styrene, and polyvinyl compounds. The other polymerizable compounds that can be copolymerized with styrene may be used alone or in combination of two or more types.

Examples of the α-olefin compounds include those having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decane, 1-dodecane, 4-methyl-1-pentene, and 3,5,5-trimethyl-1-hexene. Examples of the cyclic olefin compounds include norbornene and cyclopentene. Examples of the aromatic vinyl compounds include alkylstyrenes such as methylstyrene and isobutylstyrene, vinylnaphthalene, and vinylanthracene. Examples of the polyvinyl compounds include divinylbenzene, divinylnaphthalene, divinylanthracene, divinylbiphenyl, and alkylenebisstyrenes such as ethylenebisstyrene. The elastomer may be a styrene-α-olefin compound-polyvinyl compound copolymer.

When the elastomer is a styrene-α-olefin compound-polyvinyl compound copolymer, the ratio of styrene to the total mass of the copolymerization components may be in the range of 30 to 70 mass%. The ratio of the α-olefin compound to the total mass of the copolymerization components may be in the range of 10 to 70 mass%. The ratio of the polyvinyl compound to the total mass of the copolymerization components may be in the range of 0.05 to 10 mass% from the viewpoint of the balance between the performance as an elastomer and the heat resistance of the cured product of the resin composition. That is, the content of the styrene structural unit of the styrene-α-olefin compound-polyvinyl compound copolymer may be 30 to 70 mass%. Also, the content of the α-olefin compound structural unit may be in the range of 10 to 70 mass%. The content of the polyvinyl compound structural unit may be in the range of 0.05 to 10 mass%.

When the curable composition contains an elastomer, the content of the elastomer may be 1 part by mass or more, 5 parts by mass or more, or 10 parts by mass or more per 100 parts by mass of the total of the curable components and elastomer of the curable composition. It may also be 80 parts by mass or less, 50 parts by mass or less, or 30 parts by mass or less.

The compound having a phenolic hydroxyl group (hereinafter sometimes referred to as "compound C") is not particularly limited in its specific structure, but by adding a compound in which the ortho position of the phenolic hydroxyl group is a hydrogen atom to the curable composition, the effect of excellent long-term heat deterioration resistance of the cured product becomes more pronounced. Without being bound by a particular theory, it is believed that compound C acts as a mild radical scavenger that does not inhibit the curing of the curable composition, thereby delaying the increase in melt viscosity in the B-stage product, and as a result, the effect of excellent long-term heat deterioration resistance is obtained through the mechanism described above.

Compound C may be used alone or in combination of two or more types. The number of phenolic hydroxyl groups in one molecule of compound C may be either 1 or 2 or more. Of these, 1 or 2 is preferred, and 1 is more preferred, as this provides superior long-term heat deterioration resistance in the cured product.

Compound C is preferably a compound having a molecular weight of 500 or less, since it has excellent solvent solubility, etc. The molecular weight of compound C may be 140 or more, 150 or more, or 170 or more. It may also be 450 or less, or 400 or less.

In compound C, the aromatic ring to which the phenolic hydroxyl group is bonded is not particularly limited, and may be an aromatic hydrocarbon or a heteroaromatic ring. Specific examples include aromatic hydrocarbons such as benzene, indene, naphthalene, fluorene, anthracene, phenanthrene, tetracene, chrysene, pyrene, and triphenylene, and heteroaromatic rings such as furan, thiophene, pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, and pyrazine. Among these, aromatic hydrocarbons are preferred, and benzene and naphthalene are more preferred, since they provide a cured product with excellent dielectric properties. Compound C may also be a compound containing multiple aromatic rings, and specifically may be a compound containing two or more benzene, naphthalene, or a combination thereof.

Specific examples of compound C include compounds represented by any of the following general formulas (8) to (12).

[X in general formulas (8) to (12) represents a monovalent organic group other than a hydroxyl group, or a hydrogen atom. Multiple Xs in the formula may all be the same, or some or all of them may be different. Y in general formulas (10) to (12) represents a direct bond or a divalent organic group. In general formulas (11) and (12), Y may be bonded to any carbon atom forming a naphthalene ring.]

X in formulas (8) to (12) is a monovalent organic group other than a hydroxyl group or a hydrogen atom. Specific examples of monovalent organic groups other than a hydroxyl group include, for example, halogen atoms such as fluorine, chlorine, bromine, and iodine atoms, carboxy groups, aliphatic hydrocarbon groups (including those in which two Xs bonded to adjacent carbon atoms form an alicyclic structure), aliphatic hydrocarbon groups in which one or more carbon atoms are replaced by oxygen atoms, aliphatic hydrocarbon groups in which one or more carbon atoms are replaced by carbonyl groups, aryl groups, aryloxy groups, aralkyl groups, and aralkyloxy groups.

The aliphatic hydrocarbon group may have any structure, such as a straight chain, a branched structure, or an alicyclic structure. The number of carbon atoms in the aliphatic hydrocarbon group is not particularly limited, and may be, for example, 1 or more and 8 or less. Specific examples of aliphatic hydrocarbon groups include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, t-butyl, n-pentyl, neopentyl, 1-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, n-hexyl, isohexyl, n-heptyl, n-octyl, 2-ethylhexyl, and 1,1,3,3-tetramethylbutyl; alicyclic alkyl groups such as cyclohexyl; and alicyclic structures formed by two Xs bonded to adjacent carbon atoms, such as 5,6,7,8-tetrahydro-2-naphthol.

Examples of aliphatic hydrocarbon groups in which one or more carbon atoms have been replaced with oxygen atoms include alkoxy groups such as methoxy and ethoxy groups; alkyloxyalkylene groups such as methoxymethyl groups; and structures containing multiple oxygen atoms such as methoxymethoxy groups.

Examples of aliphatic hydrocarbon groups in which one or more carbon atoms have been replaced with a carbonyl group include acyl groups and 3-oxobutyl groups.

Examples of aryl groups include phenyl, tolyl, xylyl, mesityl, and naphthyl groups. Examples of aryloxy groups include phenyloxy, tolyloxy, xylyloxy, mesityloxy, and naphthyloxy groups.

Examples of aralkyl groups include benzyl groups, α-methylbenzyl groups, triphenylmethyl groups, naphthylmethyl groups, etc. Examples of aralkyloxy groups include benzyloxy groups, etc.

In general formulas (8) and (9), the number of monovalent organic groups among the Xs present in the formula may be 0, 1 or 2, or may be 0 or 1. In general formulas (10) to (12), the number of monovalent organic groups among the Xs present on each aromatic ring may be 0, 1 or 2, or may be 0 or 1.

The monovalent organic group may be any one of a carboxy group, an alkyl group, and an aryl group. When compound A is a compound having a carboxy group, the curable composition may have excellent long-term heat resistance of the cured product as well as excellent adhesion to metal foils such as copper foil. When the monovalent organic group is an aryl group, the curable composition may have even more excellent long-term heat resistance of the cured product.

Y in the general formulas (10) to (12) is a direct bond or a divalent organic group. Examples of divalent organic groups include ether bonds; alkylene groups having 1 to 6 carbon atoms, such as a methylene group or an isopropylidene group; cycloalkylene groups, such as a cyclohexylene group; arylene groups, such as a phenylene group or a naphthylene group; and structural moieties represented by -O-Ar-O- (Ar represents an arylene group). Y in the general formulas (10) to (12) may be a direct bond.

Some of the compounds represented by any of the general formulas (8) to (12) are exemplified below, but compound C in this disclosure is not limited to these. In the structural formula below, the substituent on the naphthalene ring may be bonded to any of the carbon atoms forming the naphthalene ring. However, the two ortho positions of the phenolic hydroxyl group are hydrogen atoms.

Compound C preferably contains a compound represented by general formula (8) or (9) because of its excellent solvent solubility. The total proportion of the compounds represented by general formula (8) or (9) in the entire compound C may be 50% by mass or more, 70% by mass or more, or 80% by mass or more. It may also be 100% by mass or less, 90% by mass or less, or 70% by mass or less.

The amount of compound C added is such that the curable composition has excellent long-term heat deterioration resistance of the cured product as well as excellent curability and dielectric properties of the cured product, and therefore the ratio of compound C to the total mass of compounds having radical polymerizable groups is preferably 0.5 mass% or more, more preferably 1 mass% or more, and particularly preferably 1.5 mass% or more. Also, it is preferably 10 mass% or less, more preferably 8 mass% or less, and particularly preferably 6 mass% or less. The ratio of compound C to the total mass of compounds having radical polymerizable groups may be, for example, in the range of 0.5 to 10 mass%, may be in the range of 1 to 8 mass%, or may be in the range of 1.5 to 6 mass%.

In addition, when the curable composition contains a thermosetting compound or an elastomer, or both, the amount of compound C added is preferably 0.5 mass% or more, more preferably 1 mass% or more, and particularly preferably 1.5 mass% or more, based on 100 mass parts in total of the curable components and elastomer in the curable composition. Also, it is preferably 10 mass% or less, more preferably 8 mass% or less, and particularly preferably 6 mass% or less. The ratio of compound C in the curable composition to 100 mass parts in total of the curable components and elastomer of the curable composition may be, for example, in the range of 0.5 to 10 mass%, may be in the range of 1 to 8 mass%, or may be in the range of 1.5 to 6 mass%.

The filler can be either an organic filler or an inorganic filler, but is preferably an inorganic filler. Examples of inorganic fillers include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titanium oxide, barium titanate, strontium titanate, potassium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, aluminum borate, silicon carbide, mica, beryllia, clay, and talc. From the viewpoint of dielectric properties, silica is preferred.

The shape and size of the filler are not particularly limited. The average particle size of the filler may be, for example, 0.01 to 20 μm, or 0.1 to 10 μm. Here, the average particle size of the filler is the particle size at the point corresponding to an accumulated value of 50% in the volume-based particle distribution measured by the laser diffraction scattering method.

When the curable composition contains a filler, the amount of filler added is preferably adjusted so that the proportion of inorganic filler in 100 parts by mass of the curable composition after heating at 130°C for 10 minutes is in the range of 50 to 85% by mass. For example, the amount of filler added to the curable composition may be in the range of 100 to 500 parts by mass per 100 parts by mass of the total of the curable components and elastomer of the curable composition.

The curing accelerator may be, for example, a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photoradical polymerization initiator, but a thermal radical polymerization initiator is preferred. The radical polymerization initiator is not particularly limited, and examples thereof include azo-based polymerization initiators and organic peroxide-based polymerization initiators. Examples of azo-based polymerization initiators include 2,2'-azobis(2,4,4-trimethylpentane), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 1,1'-azobis(cyclohexane-1-carbonitrile), and dimethyl 1,1'-azobis(1-cyclohexanecarboxylate). , 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylpropanenitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl 4-cyanopentanoate), and the like. Examples of organic peroxide polymerization initiators include dicumyl peroxide, dibenzoyl peroxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, α,α'-di(t-butylperoxy)diisopropylbenzene, and tert-butyl hydroperoxide.

When the curable composition contains a curing accelerator, the amount of the curing accelerator added may be in the range of 0.01 to 5 parts by mass per 100 parts by mass of the total of the curable components of the curable composition and the elastomer in the curable composition.

The curable composition may be solvent-free or may contain a solvent. The solvent can adjust the viscosity of the curable composition to further improve the coatability. The solvent is preferably an organic solvent.

Examples of organic solvents include alcohol-based solvents such as ethanol, propanol, butanol, methyl cellosolve, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as tetrahydrofuran; aromatic hydrocarbon-based solvents such as toluene, xylene, and mesitylene; nitrogen-containing solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; sulfur-containing solvents such as dimethylsulfoxide; and ester-based solvents such as γ-butyrolactone. Among these, those with a boiling point of 120°C or less are preferred. When using multiple organic solvents to prepare a mixed solvent, it is preferred that the mixed solvent has a boiling point of 120°C or less.

When the curable composition contains a solvent, the solid content of the curable composition is adjusted appropriately depending on the type of compound A and whether or not other compounds are contained. For example, the ratio of the solid content to the total mass of the curable composition may be in the range of 30 to 95 mass %. The solid content of the curable composition refers to the components other than the solvent in the curable composition.

The method for producing the curable composition is not particularly limited. One example of a method for producing the curable composition is a method in which compound A and any optional components used as needed are added and mixed. More specifically, for example, compound A and any optional components used as needed can be dissolved or dispersed in a solvent and mixed to obtain a curable composition. The mixing order, temperature, time, and other conditions for each component are not particularly limited, and may be appropriately adjusted depending on the type of raw material, production scale, production equipment, etc.

[Prepreg]
According to one embodiment, a prepreg including a curable composition or a semi-cured product of the curable composition can be provided. The prepreg can be formed, for example, by using the curable composition and a fiber substrate. The curable composition can be the above-mentioned curable composition. Details of the curable composition are as described above.

The prepreg contains the above-mentioned curable composition or a semi-cured product of the above-mentioned curable composition. In this disclosure, the semi-cured product can be considered to be in the B-stage state in JIS K 6800 (1985) as one indicator of the semi-cured product. The prepreg may contain, for example, the curable composition or a semi-cured product of the curable composition and a fiber substrate such as a sheet-like fiber substrate. In the prepreg, the curable composition may be in an uncured state, but the curable composition may be in a partially or entirely semi-cured state.

The prepreg can be obtained, for example, by coating a fiber substrate with a curable composition and drying it. For example, the prepreg can be obtained by impregnating and coating a fiber substrate with a curable composition and drying the fiber substrate impregnated with the curable composition. Drying is preferably performed at a temperature at which volatile components such as a solvent that may be contained in the curable composition are removed or higher, and may be performed at a temperature at which the thermosetting resin contained in the curable composition is semi-cured or higher depending on the application. In addition, drying is preferably adjusted so that the thermosetting resin contained in the curable composition is not completely cured. From this perspective, the drying temperature may be, for example, 80 to 200°C, and the drying time may be, for example, 1 to 30 minutes depending on the drying temperature, the drying device, and its scale.

The fiber substrate may be any of woven fabric, knitted fabric, and nonwoven fabric. The fiber substrate may be provided in the form of chopped strand mat, roving, etc. The fiber material may be any of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers and carbon fibers. Examples of glass fibers include E glass, NE glass, D glass, S glass, Q glass, etc. Examples of organic fibers include polyimide, polyester, tetrafluoroethylene, etc. The fiber substrate may be one of these fibers alone or two or more of these fibers in combination. From the viewpoints of dielectric properties and heat resistance, the material of the fiber substrate is preferably inorganic fiber, and more preferably glass fiber.

The fiber substrate may be selected appropriately depending on the application of the prepreg, but a sheet-like fiber substrate is preferred. The sheet-like fiber substrate may be, for example, any of the various sheet-like fiber substrates used in known laminates for electrical insulating materials. The thickness of the sheet-like fiber substrate is not particularly limited, but is preferably, for example, 0.01 to 0.1 mm. Here, the thickness is determined by measuring the thickness at five points at equal distances over the entire surface of the sheet-like fiber substrate, and taking the arithmetic average value of the five points.

[Metal-clad laminate]
According to one embodiment, a metal-clad laminate including a cured prepreg and a metal foil can be provided. The details of the curable composition and the prepreg are as described above. In the present disclosure, one index of the cured product is the C-stage state in JIS K 6800 (1985).

The metal-clad laminate preferably includes a prepreg layer and metal foil disposed on at least one surface of the prepreg layer. The prepreg layer is a cured product of the prepreg described above. For example, in the metal-clad laminate, metal foil is disposed on at least one surface of the cured product of the prepreg, and more preferably, metal foil is disposed on both surfaces of the cured product of the prepreg. The metal-clad laminate may be manufactured by disposing metal foil on at least one surface of a single sheet-like prepreg, or may be manufactured by laminating two or more sheet-like prepregs and disposing metal foil on at least one surface of the outermost surface of the laminate. For example, the metal-clad laminate may be manufactured by laminating two or more sheet-like prepregs and disposing metal foil on both surfaces of the laminate.

Below, we will explain a specific example of a method for manufacturing a metal-clad laminate, in which metal foil is placed on a laminate of two or more sheet-like prepregs.

First, two or more sheet-like prepregs are laminated to obtain a laminate. In this laminate, the two or more sheet-like prepregs may be identical to each other, or some or all of them may be different. In the laminate, at least one of the two or more sheet-like prepregs may be obtained using the curable composition for prepregs according to one embodiment.

Next, a metal foil is placed on at least one surface of this laminate. The laminate on which the metal foil is placed is heated and pressurized. This advances the curing reaction of the sheet-like prepreg, and a cured prepreg can be obtained. In addition, adjacent sheet-like prepregs can be fixed to each other. The heating and pressurizing conditions are not particularly limited, but may be, for example, a temperature of 100 to 300°C, a time of 10 to 300 minutes, and a pressure of 0.5 to 50 MPa. After heating and pressurizing, reheating may be performed to further advance the curing of the prepreg. In this case, the reheating temperature may be 100 to 300°C.
As a method for applying pressure, for example, an autoclave molding machine, a multi-stage press machine, a multi-stage vacuum press machine, a continuous molding machine, etc. can be used.

The metal of the metal foil is not particularly limited, and examples include copper, nickel, aluminum, gold, silver, platinum, molybdenum, ruthenium, tungsten, iron, titanium, chromium, and alloys containing two or more of these metal elements. Industrially, it is preferable to use the single metals copper, nickel, and aluminum. By using copper as the metal foil, it is possible to provide a copper-clad laminate.

[Printed wiring board]
According to one embodiment, a printed wiring board including a cured product of a prepreg can be provided. The printed wiring board can be manufactured using a prepreg, a metal-clad laminate, or a combination thereof. For example, a printed wiring board can be provided by forming wiring using a metal-clad laminate by a known method. The details of the prepreg and the metal-clad laminate are as described above. The printed wiring board may be either a single-layer printed wiring board or a multilayer printed wiring board.

[Semiconductor package]
According to one embodiment, a semiconductor package including a printed wiring board and a semiconductor element can be provided. More specifically, for example, a semiconductor package including a printed wiring board including a cured product of a prepreg and a semiconductor element can be provided. The semiconductor package can be manufactured, for example, by mounting a semiconductor element, a memory, and the like on a printed wiring board by a known method.

[Molded product]
According to one embodiment, a molded article including a cured product of the curable composition can be provided. The molded article is obtained by molding the curable composition into some shape, and the shape is not particularly limited. For example, the molded article may be a three-dimensional structure, a film, or a plate. The molded article may also be a composite containing a resin material, reinforcing fiber, or the like other than the curable composition of the present disclosure.

Examples of embodiments are given below. The present invention is not limited to the following embodiments.
<1> A curable composition containing a compound having a vinylbenzyl group, wherein the curable composition has a thermal history of being heated at 130°C for 10 minutes and has a minimum melt viscosity of 3,000 Pa s or less as measured in the range of 40 to 150°C.

<2> The curable composition described in <1> above, in which the melt viscosity at 60°C is 5,000 Pa·s or more when the curable composition has a thermal history of being heated at 130°C for 10 minutes and is measured in the range of 40 to 150°C.

<3> The curable composition according to <1> or <2>, wherein the ratio (V 60 )/(V _min ) of the melt viscosity value at 60°C when the melt viscosity is measured in the range of 40 to 150°C to the minimum melt viscosity value (V _min ) measured in the range of 40 _{to 150} °C in a curable composition having a thermal history of being heated at ₁₃₀ °C for 10 minutes is in the range of 3 to 10.

<4> The curable composition according to any one of <1> to <3>, containing a resin having a weight average molecular weight (Mw) in the range of 50,000 to 400,000 as the compound having a vinylbenzyl group.

<5> The curable composition according to any one of <1> to <4>, which contains an inorganic filler and has a ratio of 50 to 85 mass% in 100 parts by mass of the curable composition after heating at 130°C for 10 minutes.

<6> A prepreg comprising the curable composition described in any one of <1> to <5> or a semi-cured product of the curable composition.

<7> A metal-clad laminate comprising the cured prepreg described in <6> and a metal foil.

<8> A printed wiring board comprising the cured product of the prepreg described in <6>.

<9> A semiconductor package comprising the printed wiring board described in <8> and a semiconductor element.

<10> A molded article comprising a cured product of the curable composition described in any one of <1> to <5>.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

Measurement method of weight average molecular weight (Mw) and number average molecular weight (Mn) The weight average molecular weight and number average molecular weight were calculated from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve was approximated by a third order equation using a set of five standard polystyrene samples (PStQuick MP-H, PStQuick B [product name, Tosoh Corporation]). The GPC conditions are shown below.

Apparatus: High-speed GPC apparatus "HLC-8320GPC" (product name, Tosoh Corporation)
Detector: Ultraviolet absorption detector "UV-8320" (product name, Tosoh Corporation)
Columns: Guard column: TSKgel guardcolumn Super (HZ)-M+, column: TSKgel SuperMultipore HZ-M (2 columns), reference column: TSKgel SuperH-RC (2 columns) (all product names of Tosoh Corporation)
Column size: 4.6 x 20 mm (guard column), 4.6 x 150 mm (column), 6.0 x 150 mm (reference column)
Eluent: tetrahydrofuran Sample concentration: 10 mg/1 mL
Injection volume: 20 μL or 2 μL
Flow rate: 0.35mL/min Measurement temperature: 40℃

Production Example 1 Production of Compound Having a Vinylbenzyl Group A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet was charged with 35.6 parts by mass of indene, 101.2 parts by mass of chloromethylstyrene (*1), 7.1 parts by mass of tetra-n-butylammonium bromide (manufactured by Kanto Chemical Co., Ltd.) as a phase transfer catalyst, 0.1 parts by mass of phenothiazine as a polymerization inhibitor, and 77.6 parts by mass of toluene as a solvent, and the mixture was heated and stirred at 40° C. while blowing in nitrogen at a flow rate of 50 ml/min.

(*1) Chloromethylstyrene "CMS-P": AGC Seimi Chemical Co., Ltd., a mixture of m- and p-isomers, with m-isomer content of approximately 50% by mass and p-isomer content of approximately 50% by mass.

Next, 46.5 parts by mass of a 48% by mass aqueous solution of sodium hydroxide (manufactured by Kanto Chemical Co., Ltd.) was added as a basic compound over a period of 20 minutes. The mixture was then stirred at 60°C for 9 hours. Nitrogen was continuously blown in during the reaction. The reaction mixture was cooled to room temperature (25°C), neutralized with a 10% aqueous solution of hydrochloric acid, and then washed twice with pure water. The toluene was distilled off under reduced pressure, and the resulting viscous liquid was washed with methanol and vacuum dried to obtain a compound having a vinylbenzyl group.

The obtained compound having a vinylbenzyl group was analyzed by ¹ H-NMR, and a structure having a vinylbenzyl group directly bonded to the carbon atom at the 1st position, 3rd position, or a combination thereof of indene was confirmed. Furthermore, gel permeation chromatography (GPC) analysis revealed that the compound was a mixture of a compound having two vinylbenzyl groups and a compound having three vinylbenzyl groups. It was confirmed that the compound having three vinylbenzyl groups had two vinylbenzyl groups directly bonded to the carbon atom at the 1st position of the indene ring and one vinylbenzyl group directly bonded to the carbon atom at the 3rd position. The weight average molecular weight (Mw) of the vinylbenzyl monomer was 500. The weight average molecular weight (Mw) was measured by the above method.

Production Example 2: Production of a prepolymer using a compound having a vinylbenzyl group The compound having a vinylbenzyl group obtained above was mixed with toluene to a solid content of 60% by mass. 4000 parts by mass of a toluene solution of a compound having a vinylbenzyl group (solid content 60% by mass) and 24 parts by mass of an azo-based polymerization initiator (*2) were placed in a separable flask and stirred at 200 rpm for 1 minute. Then, the mixture was heated at 110°C ± 10°C while flowing nitrogen at 400 ml/min. The weight average molecular weight (Mw) of the reaction product was monitored, and when it reached about 150,000, heating was stopped and the mixture was cooled to obtain a toluene solution of a resin having a vinylbenzyl group. The weight average molecular weight (Mw) of the resin was 147,000. The weight average molecular weight (Mw) was measured by the above method.

(*2) 2,2'-Azobis(2,4,4-trimethylpentane): Fujifilm Wako Pure Chemical Industries, Ltd. "VR-110" (product name), 10-hour half-life temperature 110℃

Examples 1 to 3 and Comparative Example 1: Production and Evaluation of Curable Compositions Each component was blended according to the blending amounts shown in Table 1, and stirred and mixed at 25°C to prepare a curable composition having a solid content concentration of about 75% by mass. The solid content concentration was adjusted by adding toluene. When the blending amounts in Table 1 are in the form of a solution, they refer to mass % converted into solid content.
The obtained curable composition was subjected to various evaluation tests according to the following procedures. The results are shown in Table 1.

Details of each component listed in Table 1 are as follows.
Elastomer: styrene-ethylene-butylene copolymer, number average molecular weight (Mn) about 10,000
Inorganic filler: Silica having an average particle size of 2.4 μm and silica having an average particle size of 1.0 μm mixed in a mass ratio of 8:2. Curing accelerator: "Perbutyl P" manufactured by NOF Corporation, α,α'-di(t-butylperoxy)diisopropylbenzene

A prepreg was obtained by impregnating and coating a 30 μm-thick glass cloth (manufactured by Asahi Kasei Corporation) with the curable composition and drying it by heating at 130° C. for 10 minutes. The content of solids derived from the curable composition in the prepreg was about 80% by mass.

Preparation of Sample for Melt Viscosity Measurement Only the curable composition portion was pulverized into powder form from the prepreg obtained above and molded into a tablet shape with a thickness of about 1.2 mm and a diameter of 20 mm to prepare a sample for melt viscosity measurement.

Measurement of Melt Viscosity The melt viscosity of the melt viscosity measurement sample obtained above was measured under the following conditions to obtain the melt viscosity at 60° C. (V ₆₀ ) and the minimum melt viscosity (V _min ).
Measuring equipment (rheometer): "DHR-20" manufactured by TA Instruments Japan Co., Ltd.
Temperature range and temperature rise conditions: 40 to 150°C, 3°C/min

Manufacture of double-sided copper-clad laminates An electrolytic copper foil ("SI-VSP-AM-3R" (product name) manufactured by Mitsui Mining & Smelting Co., Ltd.) having a thickness of 18 μm was laminated on both sides of the prepreg obtained above, with the matte side facing the prepreg side. This was heated and pressed at 230° C. for 120 minutes under vacuum pressing conditions of 2.0 MPa to obtain a double-sided copper-clad laminate.

Evaluation of bending strength retention rate The double-sided copper-clad laminate obtained above was immersed in a copper etching solution (*3) to remove the copper foil on both sides, and a test piece of 40 mm x 25 mm was prepared. The test piece was aged in a thermostatic chamber at 200°C to prepare test pieces with aging times of 500 hours and 1000 hours, respectively. A three-point bending test was performed on the test pieces that were not aged and each test piece after aging using an autograph (Shimadzu Corporation "AG-1kNX") at a test speed of 0.05 m/min and a support distance of 1.6 mm.
The ratio (%) of the measured value of the aged test piece to the measured value of the unaged test piece was calculated and evaluated according to the following criteria.
A: 60% or more, less than 80% B: 40% or more, less than 60% C: Less than 40%

(*3) Copper etching solution: 10% by weight ammonium persulfate solution (manufactured by Mitsubishi Gas Chemical Co., Ltd.)

Measurement of copper foil peel strength retention rate The double-sided copper-clad laminate obtained above was immersed in the copper etching solution described above (*3), and the copper foil was removed leaving a 3 mm wide band portion to prepare multiple test pieces. The test pieces were aged in a thermostatic chamber at 200°C to prepare test pieces with an aging time of 1000 hours. For the test pieces that were not aged and the test pieces that were aged in a thermostatic chamber at 200°C for 1000 hours, the band portion was peeled off in a 90° direction at a speed of 50 mm/min using a tensile tester (Shimadzu Corporation's "EZ Test") to measure the copper foil peel strength.
The ratio (%) of the measured value of the aged test piece to the measured value of the unaged test piece was calculated and evaluated according to the following criteria.
A: 60% or more, less than 80% B: 40% or more, less than 60% C: Less than 40%

Evaluation of dielectric properties The double-sided copper-clad laminate obtained above was immersed in the copper etching solution described above (*3) to remove the copper foils on both sides, and a test piece of 100 mm x 40 mm was obtained. This test piece was dried at 105°C for 30 minutes and then left for 1 hour at an atmospheric temperature of 25±2°C and a humidity of 40±10% RH, after which the relative dielectric constant (Dk) and dielectric loss tangent (Df) were measured.
The measurement was performed in accordance with the SPDR method (split post dielectric resonator) in the 10 GHz band at 25° C. The measurement device used was a “PNA Network Analyzer N5227A” (product name) from Agilent Technologies.

As shown in Table 1, in Examples 1 to 3, in which the curable composition had a thermal history of being heated at 130°C for 10 minutes and had a minimum melt viscosity of 3,000 Pa·s or less measured in the range of 40 to 150°C, the cured product had excellent long-term heat deterioration resistance. Specifically, the decrease in bending strength due to aging was suppressed.

This disclosure relates to the subject matter described in Japanese Patent Application No. 2023-195165, filed on November 16, 2023, the entire disclosure of which is incorporated herein by reference. It should be noted that, in addition to what has already been described, various modifications and variations may be made to the above-described embodiments without departing from the novel and advantageous features of the present disclosure. Accordingly, all such modifications and variations are intended to be included within the scope of the appended claims.

Claims (10)

The curable composition contains a compound having a vinylbenzyl group, and the curable composition has a minimum melt viscosity (V _min ) of 3,000 Pa·s or less as measured in the range of 40 to 150° C. when the curable composition has a thermal history of being heated at 130° C. for 10 minutes. The curable composition according to claim 1, wherein the curable composition has a thermal history of being heated at 130°C for 10 minutes, and the melt viscosity at 60°C (V ₆₀ ) measured in the range of 40 to 150°C is 5,000 Pa·s or more. The curable composition according to claim 1, wherein the ratio (V 60 )/(V _min ) of the melt viscosity value at 60° C. when the melt viscosity is measured in the range of 40 to 150° C. to the minimum melt viscosity value (V _min ) measured in the range of 40 _{to 150} ° C. in a curable composition having a thermal history of being heated at 130° C. for 10 minutes is in the range of 3 to 10. The curable composition according to claim 1, comprising a prepolymer having a weight average molecular weight (Mw) in the range of 50,000 to 400,000 as the compound having a vinylbenzyl group. The curable composition according to claim 1, which contains an inorganic filler and has a ratio of 50 to 85 mass % in 100 parts by mass of the curable composition after heating at 130°C for 10 minutes. A prepreg comprising the curable composition according to any one of claims 1 to 5 or a semi-cured product of the curable composition. A metal-clad laminate comprising the cured prepreg of claim 6 and metal foil. A printed wiring board comprising the cured prepreg described in claim 6. A semiconductor package comprising the printed wiring board of claim 8 and a semiconductor element. A molded article comprising a cured product of the curable composition according to any one of claims 1 to 5.