JP7402681B2 - Curable resin compositions, dry films, copper foils with resin, cured products, and electronic components - Google Patents

Description

The present invention relates to a curable resin composition, a dry film, a resin-coated copper foil, a cured product, and an electronic component, particularly a thermosetting curable resin composition containing an epoxy resin, a dry film, a resin-coated copper foil, and a cured resin composition. Regarding products and electronic parts.

Curable resin compositions containing epoxy resins have traditionally been used as materials for forming electronic components such as printed wiring boards, and various curing agents are usually used to impart various properties to the cured product. It is used in combination with an epoxy compound (for example, Patent Document 1).

Patent No. 5396805

However, curable resin compositions for forming insulating layers of electronic components are required to be capable of forming cured products with excellent heat resistance from the viewpoint of reliability and the like. Furthermore, in recent years, with the adoption of high-speed communication, that is, the use of higher frequencies, transmission loss has tended to increase, so insulating materials for electronic components are required to have a low dielectric loss tangent that can suppress transmission loss.

In view of the above problems, an object of the present invention is to provide a curable resin composition from which a cured product with high heat resistance and low dielectric loss tangent can be obtained, a dry film having a resin layer obtained from the composition, and a resin-coated copper foil. , cured products, and electronic components.

（式（Ｉ）中、Ｒ_１～Ｒ_１５は、それぞれ、水素原子、炭素数１～８個のアルキル基およびグリシジルオキシ基のいずれかであり（ただし、Ｒ_１～Ｒ_１５の少なくとも１個がグリシジルオキシ基である））
で表されるエポキシ化合物（Ａ－１）を含有することを特徴とする硬化性樹脂組成物により達成されることが見出された。 The object of the present invention is to
(A) epoxy compound,
(B) a compound having an active ester group; and (C) a curable resin composition containing an inorganic filler, wherein the epoxy compound (A) has the following formula (I):

(In formula (I), R ₁ to R ₁₅ are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a glycidyloxy group (provided that at least one of R ₁ to R ₁₅ is glycidyloxy group))
It has been found that this can be achieved by a curable resin composition characterized by containing an epoxy compound (A-1) represented by:

で表されるエポキシ化合物であることが好ましい。 The epoxy compound (A-1) has the following formula (II)

Preferably, it is an epoxy compound represented by:

Further, preferably, the content of the epoxy compound (A-1) based on the total amount of the epoxy compound (A) and the compound having an active ester group (B) is 5% by mass or more and 25% by mass or less in terms of solid content.

（式中、Ｘ_１はそれぞれ独立的にベンゼン環またはナフタレン環を有する基であり、ｋは０または１を表し、ｎは繰り返し単位の平均で０．０５～２．５である。）で表される化合物であることが好ましい。 Moreover, (B) the compound having an active ester group is represented by the following general formula (1).

(In the formula, X ₁ is each independently a group having a benzene ring or a naphthalene ring, k represents 0 or 1, and n is 0.05 to 2.5 on average of the repeating units.) It is preferable that the compound is

（式（２）中、Ｘ_２はそれぞれ独立的に下記式（３）：

で表される基または下記式（４）：

で表される基であり、
ｍは１～６の整数であり、ｎはそれぞれ独立的に１～５の整数であり、ｑはそれぞれ独立的に１～６の整数であり、
式（３）中、ｋはそれぞれ独立的に１～５の整数であり、
式（４）中、Ｙは上記式（３）で表される基（ｋはそれぞれ独立的に１～５の整数）であり、ｔはそれぞれ独立的に０～５の整数である）
で表される構造部位を有し、その両末端が一価のアリールオキシ基である構造を有する化合物であることが好ましい。 Further, (B) the compound having an active ester group has the following general formula (2):

(In formula (2), each X ₂ is independently represented by the following formula (3):

A group represented by or the following formula (4):

is a group represented by
m is an integer from 1 to 6, n is each independently an integer from 1 to 5, q is each independently an integer from 1 to 6,
In formula (3), k is each independently an integer from 1 to 5,
In formula (4), Y is a group represented by the above formula (3) (k is each independently an integer of 1 to 5), and t is each independently an integer of 0 to 5)
It is preferable that the compound has a structure represented by the following, and both ends thereof are monovalent aryloxy groups.

Furthermore, the object of the present invention is a dry film comprising the above-mentioned curable resin composition as a resin layer;
A resin-coated copper foil comprising the above-mentioned curable resin composition as a resin layer on a copper foil or a carrier-coated copper foil;
These can also be achieved by a cured product of the above-mentioned curable resin composition, a resin layer of a dry film, or a resin layer of a resin-coated copper foil, and an electronic component characterized by having the above-mentioned cured product.

According to the curable resin composition of the present invention, the obtained cured product has both high heat resistance and low dielectric loss tangent. Further, a dry film having a resin layer obtained from the curable resin composition of the present invention, a resin-coated copper foil having a resin layer obtained from the curable resin composition of the present invention, a curable resin composition of the present invention, a dry film having a resin layer obtained from the curable resin composition of the present invention, The cured product of the resin layer of the film or the resin layer of the resin-coated copper foil, and the electronic components containing this cured product, each have high heat resistance and low dielectric loss tangent.

<Curable resin composition>
The curable resin composition of the present invention is
(A) epoxy compound,
(B) a compound having an active ester group; and (C) a curable resin composition containing an inorganic filler,
The epoxy compound (A) is characterized in that it contains an epoxy compound (A-1) represented by the below-mentioned formula (I).

(A-1) The epoxy compound has a structure in which three benzene rings are directly bonded to one central benzene ring (i.e., not via a methylene group, etc.), and molecular movement is thought to be suppressed. B) The inventor has found that by using in combination with a compound having an active ester group, it is possible to obtain a cured product with a higher glass transition temperature and lower dielectric loss tangent than when using in combination with a general phenolic curing agent. Served.

Each component contained in the curable resin composition of the present invention will be explained below. In this specification, when a numerical range is expressed as "~", it means a range that includes those numerical values (ie, . . . or more, . . . or less).

（式（Ｉ）中、Ｒ_１～Ｒ_１５は、それぞれ、水素原子、炭素数１～８個のアルキル基およびグリシジルオキシ基のいずれかであり（ただし、Ｒ_１～Ｒ_１５の少なくとも１個が、好ましくは少なくとも３個がグリシジルオキシ基である）、好ましくは、Ｒ_１～Ｒ_５、Ｒ_６～Ｒ_１０およびＲ_１１～Ｒ_１５のそれぞれの少なくとも１個が、特に好ましくはＲ_１～Ｒ_５、Ｒ_６～Ｒ_１０およびＲ_１１～Ｒ_１５のそれぞれの１個だけがグリシジルオキシ基である）で表される（Ａ－１）エポキシ化合物を含む。 [(A) Epoxy compound]
The curable resin composition of the present invention contains one or more types of (A) epoxy compounds, and the (A) epoxy compounds are represented by the following formula (I).

(In formula (I), R ₁ to R ₁₅ are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a glycidyloxy group (provided that at least one of R ₁ to R ₁₅ is , preferably at least 3 are glycidyloxy groups), preferably at least one of each of R ₁ to R ₅ , R ₆ to R ₁₀ and R ₁₁ to R ₁₅ is particularly preferably R ₁ to R ₅ , in which only one of each of R ₆ to R ₁₀ and R ₁₁ to R ₁₅ is a glycidyloxy group).

で表される化合物、１，３，５－トリス（３－グリシジルオキシフェニル）ベンゼン、１－（３－グリシジルオキシフェニル）―３，５―ビス（４－グリシジルオキシフェニル）ベンゼン、下記式（ＩＩ）

で表される１，３，５－トリス（４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（３，５－ジグリシジルオキシフェニル）ベンゼン、１，３，５－トリス（３－エチル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（２－プロピル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（３－ブチル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（２－ペンチル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（２－ヘキシル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（２－ヘプチル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（３－メチル－４－グリシジルオキシフェニル）ベンゼン、１，３，５－トリス（２－メチル－４－グリシジルオキシ－６－メチルフェニル）ベンゼンが挙げられる。 As the epoxy compound (A-1), for example, the following formula (III)

Compounds represented by, 1,3,5-tris(3-glycidyloxyphenyl)benzene, 1-(3-glycidyloxyphenyl)-3,5-bis(4-glycidyloxyphenyl)benzene, the following formula (II )

1,3,5-tris(4-glycidyloxyphenyl)benzene, 1,3,5-tris(3,5-diglycidyloxyphenyl)benzene, 1,3,5-tris(3-ethyl) represented by -4-glycidyloxyphenyl)benzene, 1,3,5-tris(2-propyl-4-glycidyloxyphenyl)benzene, 1,3,5-tris(3-butyl-4-glycidyloxyphenyl)benzene, 1 , 3,5-tris(2-pentyl-4-glycidyloxyphenyl)benzene, 1,3,5-tris(2-hexyl-4-glycidyloxyphenyl)benzene, 1,3,5-tris(2-heptyl -4-glycidyloxyphenyl)benzene, 1,3,5-tris(3-methyl-4-glycidyloxyphenyl)benzene, 1,3,5-tris(2-methyl-4-glycidyloxy-6-methylphenyl) ) benzene.

Among them, the epoxy compound (A-1) is 1,3,5-tris(3-glycidyloxyphenyl)benzene, 1,3,5-tris(4-glycidyloxyphenyl)benzene, 1,3,5-tris (3,5-diglycidyloxyphenyl)benzene is preferred, and 1,3,5-tris(4-glycidyloxyphenyl)benzene represented by the above formula (II) is particularly preferred. .

The epoxy compound (A-1) listed above can be produced by various methods, and one example is the method described in the specification of International Publication No. WO93/14140. This method produces an ether by reacting a phenolic compound such as 1,3,5-tris(4-hydroxyphenyl)benzene (also known as THPB) with epihalohydrin in the presence of a coupling catalyst such as benzyltrimethylamine chloride. Then, this ether is dehalogenated by heating in the presence of caustic alkali to obtain an epoxidized product, that is, (A-1) epoxy compound.

Here, the epihalohydrin includes epichlorohydrin, epibromohydrin, epifluorohydrin, epiiodohydrin, 3-chloro-1,2-epoxy-2-methylpropane, 3-bromo-1,2- Examples include epoxy-2-methylpropane and 1,2-epoxy-3-iodo-2-methylpropane.

In addition to the epoxy compound (A-1) described above, the epoxy compound (A) contained in the curable resin composition of the present invention may contain an epoxy compound other than the epoxy compound (A-1). (A-1) As the epoxy compound other than the epoxy compound, the following epoxy compounds can be used.

As the epoxy compound other than (A-1), any epoxy compound having one or more epoxy groups can be used, unless it falls under (A-1), and preferably one epoxy group. Examples include epoxy resins having 3 or more epoxy groups, more preferably bifunctional epoxy resins having 2 epoxy groups in the molecule, and polyfunctional epoxy resins having 3 or more epoxy groups in the molecule. Note that a hydrogenated epoxy resin may also be used.

Furthermore, it is preferable that the epoxy resin contains at least one of a trifunctional or higher functional liquid epoxy resin and a trifunctional or higher functional semisolid epoxy resin. When a trifunctional or higher functional liquid epoxy resin or a trifunctional or higher functional semisolid epoxy resin is included, the glass transition temperature can be improved while maintaining the dielectric loss tangent low.

Further, the epoxy resin may be one or more of solid epoxy resins, semi-solid epoxy resins, and liquid epoxy resins, but preferably includes solid epoxy resins. Furthermore, it is also preferable to use a liquid or semi-solid epoxy resin in the production of dry films and resin-coated copper foils.

In this specification, solid epoxy resin refers to an epoxy resin that is solid at 40°C, semi-solid epoxy resin refers to an epoxy resin that is solid at 20°C, liquid at 40°C, and liquid epoxy resin. refers to an epoxy resin that is liquid at 20°C. The determination of liquid state is made in accordance with the "Method for Confirming Liquid State" in Attachment 2 of the Ministerial Ordinance on Testing and Properties of Dangerous Substances (Ministry of Home Affairs Ordinance No. 1 of 1989). For example, the method described in paragraphs 23 to 25 of JP-A No. 2016-079384 is used.

Examples of solid epoxy resins include EPICLON HP-4700 (naphthalene type epoxy resin) manufactured by DIC, NC-7000L (naphthalene skeleton-containing polyfunctional solid epoxy resin) manufactured by Nippon Kayaku, ESN-475V manufactured by Nippon Steel Chemical & Materials, etc. naphthalene type epoxy resin; epoxidized product of a condensate of a phenol such as EPPN-502H (trisphenol epoxy resin) manufactured by Nippon Kayaku Co., Ltd. and an aromatic aldehyde having a phenolic hydroxyl group (trisphenol type epoxy resin); Dicyclopentadiene aralkyl type epoxy resin such as EPICLON HP-7200H (polyfunctional solid epoxy resin containing dicyclopentadiene skeleton) manufactured by Nippon Kayaku Co., Ltd.; NC-3000H, NC-3000L (polyfunctional solid epoxy resin containing biphenyl skeleton) manufactured by Nippon Kayaku Co., Ltd. Biphenyl aralkyl type epoxy resin; Novolak type epoxy resin such as EPICLON N660, EPICLON N690 manufactured by DIC, EOCN-104S manufactured by Nippon Kayaku Co., Ltd.; Biphenyl type epoxy resin such as YX-4000 manufactured by Mitsubishi Chemical Corporation; Nippon Steel Chemical & Materials Examples include phosphorus-containing epoxy resins such as TX0712 manufactured by Co., Ltd. By including a solid epoxy resin, the glass transition temperature of the cured product becomes high and it has excellent heat resistance. Among solid epoxy resins, epoxy resins with a skeleton in which aromatic compounds, phenol, and naphthol are connected by methylene chains, such as ESN-475V and NC3000H, can be used to obtain cured products with higher Tg and lower dielectric loss tangent. is preferred.

Further, as semi-solid epoxy resins, EPICLON 860, EPICLON 900-IM, EPICLON EXA-4816, EPICLON EXA-4822 manufactured by DIC, EPOTOTO YD-134 manufactured by Nippon Steel Chemical & Materials, jER834, jER872 manufactured by Mitsubishi Chemical, Bisphenol A type epoxy resins such as ELA-134 manufactured by Sumitomo Chemical; Naphthalene type epoxy resins such as EPICLON HP-4032 manufactured by DIC; Phenol novolak type epoxy resins such as EPICLON N-740 manufactured by DIC; jER604 manufactured by Mitsubishi Chemical Corporation Examples include epoxy resins containing nitrogen atoms such as. By containing the semi-solid epoxy resin, the cured product has a high glass transition temperature (Tg), a low coefficient of linear thermal expansion (CTE), and has excellent crack resistance. Furthermore, by including the semi-solid epoxy resin, the dry film has excellent storage stability and can prevent cracking and peeling.

Examples of liquid epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolak epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins containing heteroatoms other than nitrogen. By including a liquid epoxy resin, the flexibility of the dry film can be improved.

In order to improve the balance between tack-free properties and flexibility of the resin layer of the dry film, it is also preferable to use an epoxy resin containing nitrogen atoms, and the proportion of liquid epoxy resin and semi-solid epoxy resin in the total mass of component A. It is more preferable to set the amount in the range of 5% to 50%.

As mentioned above, from the viewpoint of providing a low dielectric loss tangent to the cured product of the curable resin composition, the blending amount of the epoxy compound (A) should be 100% of the solid content in the resin composition. In terms of mass %, it is preferably 20 mass % or less, more preferably 15 mass % or less, and particularly preferably 8 mass % or less. Further, from the viewpoint of the strength of the cured product, the lower limit is preferably 1% by mass or more, more preferably 3% by mass or more.

Further, it is preferable that the content of the epoxy compound (A-1) relative to the total amount of the epoxy compound (A) and the compound having an active ester group (B) is 5% by mass or more and 25% by mass or less in terms of solid content, It is more preferably 5% by mass or more and 20% by mass, most preferably 5% by mass or more and 19% by mass or less. The content of (A-1) epoxy compound with respect to the total amount of (A) epoxy compound and (B) compound having an active ester group is in the range of 5% by mass or more and 25% by mass or less in terms of solid content, By using (A-1) and component (B) together, the effect of improving heat resistance and lowering the dielectric loss tangent becomes even greater.

The curable resin composition of the present invention may contain a thermosetting resin in addition to the epoxy compound within a range that does not impair the effects of the present invention, such as isocyanate compounds, blocked isocyanate compounds, amino resins, benzene resins, etc. Known and commonly used thermosetting resins such as oxazine resins, carbodiimide resins, cyclocarbonate compounds, polyfunctional oxetane compounds, episulfide resins, and maleimide resins can be used.

[(B) Compound having active ester group]
The curable resin composition of the present invention contains (B) a compound having an active ester group as a curing agent for (A) an epoxy compound.

(B) A compound having an active ester group is a compound having one or more, preferably two or more active ester groups in one molecule. A compound having an active ester group can generally be obtained by a condensation reaction between a carboxylic acid compound and a hydroxy compound. Among these, compounds having an active ester group obtained by using a phenol compound or a naphthol compound as the hydroxy compound are preferred. Examples of phenolic compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalin, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol , dicyclopentadienyl diphenol, phenol novolak, and the like. Further, (B) the compound having an active ester group may be of the naphthalene diol alkyl/benzoic acid type. (B) The compound having an active ester group may be used alone or in combination of two or more. (B) The compound having an active ester group is preferably one having a benzene, α-naphthol, β-naphthol, or dicyclopentadiene skeleton.

(B) Among the compounds having an active ester group, the following compounds (B1) and (B2) having an active ester group can be suitably used.

(B1) The compound having an active ester group includes (b1) a phenol resin having a molecular structure in which phenols are linked via an aliphatic cyclic hydrocarbon group, (b2) an aromatic dicarboxylic acid or its halide, and ( b3) It has a structure obtained by reacting an aromatic monohydroxy compound. The phenolic hydroxyl group in the phenolic resin (b1) is 0.05 to 0.75 mol per 1 mol of the carboxyl group or acid halide group in the aromatic dicarboxylic acid or its halide (b2), and the phenolic hydroxyl group in the phenolic resin (b3) is 0.05 to 0.75 mol. It is preferable to have a structure obtained by reacting an aromatic monohydroxy compound in a proportion of 0.25 to 0.95 mol.

Here, in (b1) phenol resin, the molecular structure in which phenols are linked via aliphatic cyclic hydrocarbon groups is an unsaturated aliphatic cyclic hydrocarbon compound containing two double bonds in one molecule. Examples include structures obtained by polyaddition reaction with phenols. Examples of the phenols include unsubstituted phenols and substituted phenols substituted with one or more alkyl groups, alkenyl groups, allyl groups, aryl groups, aralkyl groups, or halogen groups. Specific examples of substituted phenols include cresol, xylenol, ethylphenol, isopropylphenol, butylphenol, octylphenol, nonylphenol, vinylphenol, isopropenylphenol, allylphenol, phenylphenol, benzylphenol, chlorophenol, bromophenol, naphthol, and dihydroxynaphthalene. Examples include, but are not limited to. Also, a mixture of these may be used. Among these, unsubstituted phenol is particularly preferred because of its excellent fluidity and curability.

Specific examples of unsaturated alicyclic hydrocarbon compounds include dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, 5-vinylnorbon-2-ene, α-pinene, β-pinene, and limonene. Can be mentioned. Among these, dicyclopentadiene is preferred from the viewpoint of property balance, particularly heat resistance and hygroscopicity. In addition, since dicyclopentadiene is contained in petroleum fractions, industrial dicyclopentadiene may contain other aliphatic or aromatic dienes as impurities, but it has good heat resistance, hardenability, Considering moldability and the like, it is desirable that the product has dicyclopentadiene purity of 90% by mass or more.

Next, the aromatic dicarboxylic acid or its halide (b2) is an aromatic dicarboxylic acid such as isophthalic acid, terephthalic acid, 1,4-, 2,3-, or 2,6-naphthalene dicarboxylic acid, and Examples include acid halides such as acid fluorides, acid chlorides, acid bromides, and acid iodides. Among these, acid chlorides of aromatic dicarboxylic acids are preferred because of their particularly good reactivity, and among these, isophthalic acid dichloride and terephthalic acid dichloride are preferred, with isophthalic acid dichloride being particularly preferred.

Next, (b3) aromatic monohydroxy compounds include, for example, phenol; alkylphenols such as o-cresol, m-cresol, p-cresol, and 3,5-xylenol; o-phenylphenol, p-phenylphenol, Examples include aralkylphenols such as 2-benzylphenol, 4-benzylphenol, and 4-(α-cumyl)phenol; and naphthols such as α-naphthol and β-naphthol. Among these, α-naphthol and β-naphthol are particularly preferred since the dielectric loss tangent of the cured product is low.
(B1) The active ester compound has a structure obtained by reacting (b1) a phenol resin, (b2) an aromatic dicarboxylic acid or its halide, and (b3) an aromatic monohydroxy compound. , the following general formula (1)

(In the formula, X ₁ is a group having a benzene ring or a naphthalene ring, k represents 0 or 1, and n is an average value of repeating units of 0.05 to 2.5.)
Those having the structure represented by the above are particularly preferred because the dielectric loss tangent of the cured product is low and the solution viscosity when dissolved in an organic solvent is low. The group having a benzene ring or naphthalene ring is not particularly limited, and may be a phenyl group, a naphthyl group, etc., or the benzene ring or naphthalene ring may be bonded to the molecular terminal via another atom, and the group may be substituted. It may have a group. Moreover, it is preferable that the active ester compound (B1) has a naphthalene ring at the end of its molecule.

In particular, those in which the value of n in the above general formula (1), that is, the average value of repeating units, is in the range of 0.25 to 1.5 have low solution viscosity and are easy to manufacture into dry films for build-up. It is preferable from this point of view. Further, in the above general formula (1), the value of k is preferably 0 from the viewpoint of high heat resistance and low dielectric loss tangent.

Here, n in the above general formula (1) can be determined as follows.

[How to find n in general formula (1)]
Styrene equivalent molecular weights (α1, α2, α3, α4) corresponding to n = 1, n = 2, n = 3, n = 4, respectively, and n = 1, n = according to GPC measurements performed under the following conditions. 2, find the ratios (β1/α1, β2/α2, β3/α3, β4/α4) with the theoretical molecular weights (β1, β2, β3, β4) of n=3 and n=4, and calculate these (β1/α1). Find the average value of α1 to β4/α4). The average molecular weight is determined by multiplying the number average molecular weight (Mn) determined by GPC by this average value. Next, the value of n is calculated using the molecular weight of the general formula (1) as the average molecular weight.

(GPC measurement conditions)
Measuring device: “HLC-8220 GPC” manufactured by Tosoh Corporation,
Column: Tosoh guard column “HXL-L”
+ “TSK-GEL G2000HXL” manufactured by Tosoh Corporation
+ “TSK-GEL G2000HXL” manufactured by Tosoh Corporation
+ “TSK-GEL G3000HXL” manufactured by Tosoh Corporation
+ “TSK-GEL G4000HXL” manufactured by Tosoh Corporation
Detector: RI (differential refractive diameter)
Data processing: Tosoh Corporation “GPC-8020 Model II version 4.10”
Measurement conditions: Column temperature 40℃
Developing solvent: Tetrahydrofuran Flow rate: 1.0 ml/min Standard: The following monodisperse polystyrene with a known molecular weight was used in accordance with the measurement manual of the above-mentioned "GPC-8020 Model II Version 4.10".

(Polystyrene used)
“A-500” manufactured by Tosoh Corporation
“A-1000” manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
“A-5000” manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
“F-10” manufactured by Tosoh Corporation
Tosoh Corporation "F-20"
“F-40” manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
Tosoh Corporation "F-128"
Sample: A 1.0% by mass tetrahydrofuran solution in terms of resin solid content was filtered through a microfilter (50 μl).

Specifically, the method of reacting (b1) a phenol resin, (b2) an aromatic dicarboxylic acid or its halide, and (b3) an aromatic monohydroxy compound involves reacting each of these components in the presence of an alkali catalyst. can be done.

Examples of alkali catalysts that can be used here include sodium hydroxide, potassium hydroxide, triethylamine, and pyridine. Among these, sodium hydroxide and potassium hydroxide are particularly preferred because they can be used in the form of an aqueous solution and have good productivity.

Specifically, in the reaction, (b1) a phenol resin, (b2) an aromatic dicarboxylic acid or its halide, and (b3) an aromatic monohydroxy compound are mixed in the presence of an organic solvent, and the alkali catalyst or its halide is mixed. A method of reacting while dropping an aqueous solution continuously or intermittently may be mentioned. At that time, the concentration of the aqueous solution of the alkali catalyst is preferably in the range of 3.0 to 30%. Furthermore, examples of organic solvents that can be used here include toluene and dichloromethane.

After the reaction is completed, if an aqueous solution of an alkaline catalyst is used, the reaction solution is separated by standing, the aqueous layer is removed, and the remaining organic layer is washed repeatedly until the aqueous layer becomes almost neutral. The desired resin can be obtained.

The active ester group-containing compound (B1) obtained in this way is usually obtained as a solution in an organic solvent, so when it is used as a varnish for laminates or a dry film for build-up, it can be used as is with other ingredients. The desired curable resin composition can be produced by mixing with the organic solvent and adjusting the amount of the organic solvent as appropriate. The active ester compound (B1) is characterized by a low melt viscosity when dissolved in an organic solvent to form a resin solution. Specifically, the active ester compound in a toluene solution with a solid content of 65% is The solution viscosity of a compound having this is 300 to 10,000 mPa·s (25°C).

で表される構造部位を有し且つその両末端が一価のアリールオキシ基である構造を有するものである。 The compound having an active ester group (B2) has the following general formula (2):

It has a structure represented by the following and has a structure in which both ends thereof are monovalent aryloxy groups.

で表される基または下記式（４）：

で表される基であり、ｍは１～６の整数であり、ｎはそれぞれ独立的に１～５の整数であり、ｑはそれぞれ独立的に０～６の整数であり、式（３）中、ｋはそれぞれ独立的に１～５の整数であり、式（４）中、Ｙは上記式（３）で表される基（ｋはそれぞれ独立的に１～５の整数）であり、ｔはそれぞれ独立的に０～５の整数である）
（Ｂ２）の活性エステル基を有する化合物は、前記一般式（２）中の

で表される部分構造が、水酸基当量が１７０～２００グラム／当量の変性ナフタレン化合物の由来構造であることが好ましい。 (In formula (2), each X ₂ is independently represented by the following formula (3):

A group represented by or the following formula (4):

m is an integer of 1 to 6, n is each independently an integer of 1 to 5, q is each independently an integer of 0 to 6, and formula (3) where k is each independently an integer of 1 to 5, and in formula (4), Y is a group represented by the above formula (3) (k is each independently an integer of 1 to 5), (t is each independently an integer from 0 to 5)
The compound (B2) having an active ester group is represented by the general formula (2) above.

The partial structure represented by is preferably a structure derived from a modified naphthalene compound having a hydroxyl equivalent of 170 to 200 grams/equivalent.

In order to clarify the relationship between m and n in formula (2), some patterns are illustrated below, but the compound having an active ester group (B2) is not limited to these.

For example, when m=1, formula (2) represents the structure of formula (2-I) below.

In formula (2-I), n is an integer of 1 to 5, and when n is 2 or more, q is each independently an integer of 0 to 6.

Further, for example, when m=2, formula (2) represents the structure of formula (2-II) below.

In formula (2-II), n is each independently an integer of 1 to 5, and when n is 2 or more, q is each independently an integer of 0 to 6.

Since the compound having an active ester group (B2) has a naphthylene ether structural part in the main molecule skeleton, it can impart superior heat resistance and flame retardance to the cured product, and the structural part has the following formula ( Since the cured product has a structure bonded at the structural sites represented by 5), it is possible to provide a cured product with excellent dielectric properties. In addition, by having an aryloxy group as a structure at both ends in the structure of the compound having an active ester group (B2), the heat decomposition resistance of the cured product can be sufficiently improved even in multilayer printed circuit board applications. can get.

The active ester group-containing compound (B2) is preferably one having a softening point in the range of 100 to 200°C, particularly 100 to 190°C, in view of the excellent heat resistance of the cured product.

Among the compounds having an active ester group (B2), m in formula (2) may be an integer of 1 to 6. Among these, those in which m is an integer of 1 to 5 are preferred. In addition, n in formula (2) is each independently an integer of 1 to 5. Among these, those in which n is an integer of 1 to 3 are preferred.

To describe the relationship between m and n in formula (2), for example, if m is an integer of 2 or more, n of 2 or more will occur, but in that case, each n is an independent value. be. That is, as long as n is within the numerical range, the values may be the same or different.

In the compound (B2) having an active ester group, when q is 1 or more in formula (2), X ₂ may be substituted at any position in the naphthalene ring structure.

The aryloxy groups at both ends of the structure include those derived from monohydric phenolic compounds such as phenol, cresol, pt-butylphenol (para-tert-butylphenol), 1-naphthol, and 2-naphthol. Among these, from the viewpoint of heat decomposition resistance of the cured product, phenoxy group, tolyloxy group or 1-naphthyloxy group are preferred, and 1-naphthyloxy group is more preferred.

Hereinafter, the method for producing the compound having an active ester group (B2) will be described in detail.

The method for producing a compound having an active ester group (B2) includes a step of reacting a dihydroxynaphthalene compound and benzyl alcohol in the presence of an acid catalyst to obtain a benzyl-modified naphthalene compound (hereinafter, this step is referred to as "Step 1"). ), then a step of reacting the obtained benzyl-modified naphthalene compound with an aromatic dicarboxylic acid chloride and a monohydric phenol compound (hereinafter, this step may be abbreviated as "Step 2"). ).

That is, first, in step 1, the dihydroxynaphthalene compound and benzyl alcohol are reacted in the presence of an acid catalyst to form a compound that has a naphthylene structure as a main skeleton, has phenolic hydroxyl groups at both ends, and has a naphthylene structure as its main skeleton. A benzyl-modified naphthalene compound having a structure in which a benzyl group is bonded pendantly to an aromatic nucleus can be obtained. It should be noted here that in general, when a dihydroxynaphthalene compound is converted into naphthylene ether under an acid catalyst, it is extremely difficult to control the molecular weight and the resulting product has a high molecular weight. By using these together, it is possible to suppress such an increase in molecular weight and obtain a resin suitable for electronic material applications.

Furthermore, by adjusting the amount of benzyl alcohol used, in addition to being able to adjust the content of benzyl groups in the target benzyl-modified naphthalene compound, it is also possible to adjust the melt viscosity of the benzyl-modified naphthalene compound itself. Become. That is, the reaction ratio of the dihydroxynaphthalene compound and benzyl alcohol is usually such that the reaction ratio of the dihydroxynaphthalene compound and benzyl alcohol (dihydroxynaphthalene compound)/(benzyl alcohol) is 1/0.1 to 1 on a molar basis. /10, but from the balance of heat resistance, flame retardance, dielectric properties, and heat decomposition resistance, the reaction ratio of the dihydroxynaphthalene compound and benzyl alcohol (dihydroxynaphthalene compound) on a molar basis /(benzyl alcohol) is preferably in the range of 1/0.5 to 1/4.0.

Dihydroxynaphthalene compounds that can be used here include, for example, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, -dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene and the like. Among these, 1,6-dihydroxynaphthalene is preferred because the resulting cured product of the benzyl-modified naphthalene compound has better flame retardancy, and the cured product also has a lower dielectric loss tangent and better dielectric properties. Alternatively, 2,7-dihydroxynaphthalene is preferred, and 2,7-dihydroxynaphthalene is more preferred.

Acid catalysts that can be used in the reaction between the dihydroxynaphthalene compound and benzyl alcohol in Step 1 include, for example, inorganic acids such as phosphoric acid, sulfuric acid, and hydrochloric acid, oxalic acid, benzenesulfonic acid, toluenesulfonic acid, methanesulfonic acid, and fluoromethane. Examples include organic acids such as sulfonic acid, Friedel-Crafts catalysts such as aluminum chloride, zinc chloride, stannic chloride, ferric chloride, and diethyl sulfate.

Further, the amount of the acid catalyst to be used can be appropriately selected depending on the target modification rate, etc., but for example, in the case of an inorganic acid or an organic acid, 0.001 to 5. 0 parts by weight, preferably 0.01 to 3.0 parts by weight, and in the case of Friedel-Crafts catalysts, 0.2 to 3.0 mol, preferably 0.5 to 3.0 mol, per mol of the dihydroxynaphthalene compound. The amount is preferably within a range of 2.0 mol.

The reaction between the dihydroxynaphthalene compound and benzyl alcohol in Step 1 can be carried out without a solvent, or in a solvent in order to improve the uniformity of the reaction system. Examples of such solvents include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monopropyl ether. , diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether; nonpolar aromatic solvents such as benzene, toluene, xylene; nonpolar aromatic solvents such as dimethylformamide and dimethyl sulfoxide; Protic polar solvents include chlorobenzene and the like.

A specific method for carrying out the reaction in step 1 is to dissolve the dihydroxynaphthalene compound, benzyl alcohol, and the acid catalyst in the absence of a solvent or in the presence of the solvent, and then heat the reaction at a temperature of about 60 to 180°C, preferably about 80 to 160°C. It can be carried out under temperature conditions. Further, the reaction time is not particularly limited, but is preferably 1 to 10 hours. Therefore, the reaction can be specifically carried out by maintaining the temperature for 1 to 10 hours. Further, it is preferable to distill off water generated during the reaction outside the system using a fractionating tube or the like, since the reaction proceeds quickly and productivity is improved.

Furthermore, if the obtained benzyl-modified naphthalene compound is highly colored, an antioxidant or a reducing agent may be added to the reaction system in order to suppress it. Examples of the antioxidant include hindered phenol compounds such as 2,6-dialkylphenol derivatives, divalent sulfur compounds, and phosphite ester compounds containing a trivalent phosphorus atom. Examples of the reducing agent include hypophosphorous acid, phosphorous acid, thiosulfuric acid, sulfurous acid, hydrosulfite, or salts thereof.

After the reaction is completed, the acid catalyst is removed by neutralization, washing with water, or decomposition, and the desired resin having a phenolic hydroxyl group can be separated by common operations such as extraction and distillation. Neutralization treatment and water washing treatment may be carried out according to conventional methods, and for example, basic substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, triethylenetetramine, and aniline can be used as the neutralizing agent.

Here, specific examples of the aromatic dicarboxylic acid chloride include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. Examples include acid chlorides. Among these, isophthalic acid chloride and terephthalic acid chloride are preferred from the viewpoint of the balance between solvent solubility and heat resistance.

Specific examples of the monohydric phenol compound include phenol, cresol, pt-butylphenol, 1-naphthol, and 2-naphthol. Among them, phenol, cresol, and 1-naphthol are preferred from the viewpoint of good reactivity with carboxylic acid chloride, and 1-naphthol is more preferred from the viewpoint of good heat decomposition resistance.

Here, in the method of reacting the benzyl-modified naphthalene compound, the aromatic dicarboxylic acid chloride, and further the monohydric phenol compound, specifically, each of these components can be reacted in the presence of an alkali catalyst.

Examples of alkali catalysts that can be used here include sodium hydroxide, potassium hydroxide, triethylamine, and pyridine. Among these, sodium hydroxide and potassium hydroxide are particularly preferred because they can be used in the form of an aqueous solution and have good productivity.

Specifically, the reaction can be carried out by mixing the above-mentioned components in the presence of an organic solvent, and allowing the reaction to occur while continuously or intermittently dropping the alkali catalyst or its aqueous solution. At this time, the concentration of the aqueous solution of the alkali catalyst is preferably in the range of 3.0 to 30% by mass. Furthermore, examples of organic solvents that can be used here include toluene, dichloromethane, and chloroform.

After the reaction is completed, if an aqueous solution of an alkaline catalyst is used, the reaction solution is separated by standing, the aqueous layer is removed, and the remaining organic layer is washed repeatedly until the aqueous layer becomes almost neutral. The desired resin can be obtained.

It is preferable that the compound (B2) having an active ester group obtained in this way has a softening point of 100 to 200° C., since the solubility in organic solvents will be high.

(B) When the solid content in the resin composition is 100% by mass, the upper limit of the compounding amount of the compound having an active ester group is preferably 50% by mass or less, and 40% by mass or less, from the viewpoint of the strength of the cured product. It is more preferably at most 30% by mass, particularly preferably at most 30% by mass. Moreover, since a cured product with a lower dielectric loss tangent can be obtained, the lower limit is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more.

Conventionally, it was thought that heat resistance deteriorates when a large amount of a compound having an active ester group is blended as a curing agent, but surprisingly, it has a high glass transition temperature (Tg), low dielectric loss tangent, and low coefficient of linear thermal expansion. A cured product can be obtained. Although the detailed mechanism is not clear, increasing the proportion of a compound having an active ester group, preferably a compound having an active ester group having the structure of general formula (1) or (2) above, changes the structure of the active ester, that is, It is thought that the increase in the volume ratio of the aromatic ester structure, which is rigid and has high molecular orientation, controls the movement of the chain parts between the crosslinking points, thereby improving the glass transition temperature.

In addition, in order to obtain a cured product having both high heat resistance and low dielectric loss tangent from the curable resin composition of the present invention, it is necessary to reduce the total amount of epoxy groups in (A) epoxy compound to (B) a compound having an active ester group. The ratio of ester groups to the total amount is preferably 0.2 or more and 1.2 or less, more preferably 0.2 or more and 0.6 or less, even more preferably 0.2 or more and 0.5 or less, and particularly preferably 0.2. 0.4 or less.

The above-mentioned total amount of epoxy groups can be determined by dividing the amount of the epoxy compound (A) contained in the composition by the epoxy equivalent of the epoxy compound (A). The total amount of active ester groups in the compound having an active ester group (B) is the amount of the compound having an active ester group (B) in the composition. It can be determined by dividing by the equivalent weight.

Note that (A) the epoxy compound and (B) the compound having an active ester group may each contain multiple types of compounds as described below, but in that case, the blending amount for each compound is Dividing by the equivalent weight or active ester equivalent weight determines the total amount of epoxy groups or total amount of ester groups.

The curable resin composition of the present invention may contain a curing agent other than (B) a compound having an active ester group, as long as the effects of the present invention are not impaired. For example, a compound having a phenolic hydroxyl group, a polyester Examples include carboxylic acids and their acid anhydrides, compounds having a cyanate ester group, and alicyclic olefin polymers.

[(C) Inorganic filler]
The curable resin composition of the present invention contains (C) an inorganic filler. (C) By containing an inorganic filler, the resulting cured product suppresses curing shrinkage and has a lower CTE (coefficient of thermal expansion), which improves adhesion, hardness, and thermal strength with conductor layers such as copper surrounding the insulating layer. Thermal properties such as crack resistance can be improved by combining the above. (C) As the inorganic filler, conventionally known inorganic fillers can be used, and examples thereof include, but are not limited to, silica such as barium sulfate, barium titanate, amorphous silica, crystalline silica, fused silica, and spherical silica; Extender pigments such as talc, clay, Neuburg silica particles, boehmite, magnesium carbonate, calcium carbonate, titanium oxide, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, calcium zirconate, copper, tin, zinc, nickel, Examples include metal powders such as silver, palladium, aluminum, iron, cobalt, gold, and platinum. (C) The inorganic filler is preferably spherical particles. Among these, silica is preferred because it suppresses curing shrinkage of the cured product of the curable resin composition, provides a lower CTE, and can improve properties such as adhesion and hardness. The average particle diameter (median diameter, D50) of the inorganic filler (C) is preferably 0.01 to 10 μm. (C) The inorganic filler is preferably silica having an average particle diameter of 0.01 to 3 μm. In addition, in this specification, the average particle diameter of the inorganic filler (C) is an average particle diameter including not only the particle diameter of primary particles but also the particle diameter of secondary particles (agglomerates). The average particle size can be determined using a laser diffraction particle size distribution measuring device. Examples of a measuring device using a laser diffraction method include Microtrac MT3000II manufactured by Microtrac Bell Co., Ltd.

(C) The inorganic filler is preferably a surface-treated inorganic filler. As the surface treatment, surface treatment with a coupling agent or surface treatment without introducing an organic group such as alumina treatment may be performed. (C) The method for surface treatment of the inorganic filler is not particularly limited, and any known and commonly used method may be used. What is necessary is to treat the surface of the inorganic filler.

(C) The surface treatment of the inorganic filler is preferably surface treatment using a coupling agent. As the coupling agent, silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents can be used. Among these, silane coupling agents are preferred. Examples of such silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-amino Propyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxy Examples include cyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane, which may be used alone or in combination. can be used. These silane coupling agents are preferably immobilized on the surface of the inorganic filler in advance by adsorption or reaction. Here, the amount of the coupling agent to be treated with respect to 100 parts by mass of the inorganic filler is, for example, 0.1 to 10 parts by mass, preferably 0.5 to 10 parts by mass.

As the curable reactive group, a thermosetting reactive group is preferred. Examples of thermosetting reactive groups include hydroxyl group, carboxyl group, isocyanate group, amino group, imino group, epoxy group, oxetanyl group, mercapto group, methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group, oxazoline group, etc. can be mentioned. Among these, at least one of an amino group and an epoxy group is preferred. Note that the surface-treated inorganic filler may have a photocurable reactive group in addition to the thermosetting reactive group.

The surface-treated inorganic filler may be contained in the resin layer formed from the curable resin composition in a surface-treated state, and the inorganic filler and the surface treatment may be contained in the curable resin composition forming the resin layer. Although the inorganic filler may be surface-treated in the composition by separately blending the filler with the filler, it is preferable to blend the inorganic filler that has been surface-treated in advance. By blending an inorganic filler that has been surface-treated in advance, it is possible to prevent a decrease in crack resistance and the like due to the surface treatment agent that would remain if it were blended separately and was not consumed in the surface treatment. When surface-treated in advance, it is preferable to blend a pre-dispersion liquid in which an inorganic filler is pre-dispersed in a solvent or a curable resin. Alternatively, it is more preferable that the surface-untreated inorganic filler is sufficiently surface-treated when it is pre-dispersed in a solvent, and then the pre-dispersion is blended into the composition.

(C) The inorganic filler may be blended with an epoxy resin etc. in a powder or solid state, or may be blended with an epoxy resin etc. after being mixed with a solvent or a dispersant to form a slurry.

(C) The inorganic filler may be used alone or as a mixture of two or more. (C) The blending amount of the inorganic filler is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% by mass or more, when the solid content in the resin composition is 100% by mass. Further, from the viewpoint of the toughness of the cured film, the content is preferably 90% by mass or less, more preferably 80% by mass or less, and particularly preferably 75% by mass or less.

In this specification, the solid content in the resin composition means components excluding organic solvents.

[Thermoplastic resin]
The curable resin composition of the present invention may further contain a thermoplastic resin in order to improve the mechanical strength of the resulting cured film. Preferably, the thermoplastic resin is soluble in a solvent. When it is soluble in a solvent, flexibility is improved when it is formed into a dry film, and cracking and powder falling can be suppressed. As the thermoplastic resin, thermoplastic polyhydroxypolyether resin, phenoxy resin which is a condensation product of epichlorohydrin and various bifunctional phenol compounds, or various acid anhydrides and acid chlorides are used to replace the hydroxyl group of the hydroxyether moiety present in the skeleton. and esterified phenoxy resins, polyvinyl acetal resins, polyamide resins, polyamideimide resins, block copolymers, and the like. Thermoplastic resins can be used alone or in combination of two or more. Among these thermoplastic resins, phenoxy resin is preferred because it can improve the glass transition temperature while maintaining a low dielectric loss tangent.

Polyvinyl acetal resin can be obtained, for example, by acetalizing polyvinyl alcohol resin with aldehyde. The aldehyde used here is not particularly limited, and examples include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, benzaldehyde, 2-methylbenzaldehyde, 3 Examples include -methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, and β-phenylpropionaldehyde, with butyraldehyde being preferred.

Specific examples of phenoxy resins include FX280S and FX293 manufactured by Nippon Steel Chemical & Materials, jER (registered trademark) YX8100BH30, jER (registered trademark) YX6954BH30, YL6954, YL6974, and jER (registered trademark) YX7200B35 manufactured by Mitsubishi Chemical Corporation. can be mentioned. Specific examples of polyvinyl acetal resins include the S-LEC KS series manufactured by Sekisui Chemical Co., Ltd., polyamide resins include the KS5000 series manufactured by Hitachi Chemical Co., Ltd., and the BP series manufactured by Nippon Kayaku Co., Ltd., and polyamide-imide resins such as , KS9000 series manufactured by Hitachi Chemical, etc.

The blending amount of the thermoplastic resin is calculated based on the solid content, and when the total of (A) the epoxy compound and (B) the compound having an active ester group in the resin composition is 100% by mass, the amount of the cured film obtained is determined by the mechanical From the viewpoint of physical strength, the content is preferably 0.1% by mass or more, more preferably 0.3% by mass or more. Further, from the viewpoint of the dielectric properties of the cured film, the content is preferably 20% by mass or less, more preferably 15% by mass or less.

[Curing accelerator]
The curable resin composition of the present invention can contain a curing accelerator. A curing accelerator accelerates a thermosetting reaction, and is used to further improve properties such as adhesion, chemical resistance, and heat resistance.

In the present invention, the curing accelerator can be used mainly to accelerate the reaction of (A) the epoxy compound and (B) the compound having an active ester group.

Specific examples of curing accelerators for curing reactions with (A) epoxy compounds and (B) compounds having active ester groups include imidazole and its derivatives; guanamines such as acetoguanamine and benzoguanamine; diaminodiphenylmethane, m-phenylene Polyamines such as diamine, m-xylene diamine, diaminodiphenylsulfone, dicyandiamide, urea, urea derivatives, melamine, polybasic hydrazide; organic acid salts and/or epoxy adducts thereof; amine complexes of boron trifluoride; ethyldiamino- Triazine derivatives such as S-triazine, 2,4-diamino-S-triazine, 2,4-diamino-6-xylyl-S-triazine; trimethylamine, triethanolamine, N,N-dimethyloctylamine, N-benzyl Amines such as dimethylamine, pyridine, dimethylaminopyridine, N-methylmorpholine, hexa(N-methyl)melamine, 2,4,6-tris(dimethylaminophenol), tetramethylguanidine, m-aminophenol; polyvinylphenol , polyphenols such as polyvinylphenol bromide, phenol novolak, and alkylphenol novolak; organic phosphines such as tributylphosphine, triphenylphosphine, and tris-2-cyanoethylphosphine; tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide , phosphonium salts such as hexadecyltributylphosphonium chloride; quaternary ammonium salts such as benzyltrimethylammonium chloride and phenyltributylammonium chloride; the above-mentioned polybasic acid anhydrides; diphenyliodonium tetrafluoroboroate, triphenylsulfonium hexafluoroantimonate, 2 , 4,6-triphenylthiopyrylium hexafluorophosphate and other photocationic polymerization catalysts; styrene-maleic anhydride resin; equimolar reaction products of phenyl isocyanate and dimethylamine, and organic polyisocyanates such as tolylene diisocyanate and isophorone diisocyanate. Conventionally known curing accelerators include equimolar reactants of dimethylamine and dimethylamine, metal catalysts, and the like. Among the curing accelerators, imidazole and its derivatives, and dimethylaminopyridine are preferred.

The curing accelerator can be used alone or in combination of two or more. When a curing accelerator is blended into the curable resin composition of the present invention, its blending amount is determined based on the storage of the resin composition before the thermosetting reaction, assuming that the total solid content of components A and B is 100% by mass. From the viewpoint of stability, the content is preferably 5% by mass or less, more preferably 3% by mass or less. From the viewpoint of curability, the content is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more.

[Rubber-like particles]
The curable resin composition can contain rubber particles as necessary. Such rubber particles include polybutadiene rubber, polyisopropylene rubber, urethane-modified polybutadiene rubber, epoxy-modified polybutadiene rubber, acrylonitrile-modified polybutadiene rubber, carboxyl-modified polybutadiene rubber, acrylonitrile-butadiene rubber modified with a carboxyl group or a hydroxyl group, and These include crosslinked rubber particles, core-shell type rubber particles, etc., and one type can be used alone or two or more types can be used in combination. These rubber-like particles are added to improve the flexibility of the resulting cured film, improve crack resistance, enable surface roughening treatment with oxidizing agents, and improve adhesion strength with copper foil, etc. be done.

The average particle size of the rubbery particles is preferably in the range of 0.005 to 1 μm, more preferably in the range of 0.2 to 1 μm. The average particle diameter of the rubbery particles in the present invention can be determined using a laser diffraction particle size distribution measuring device. For example, rubber particles are uniformly dispersed in a suitable organic solvent using ultrasonic waves, etc., the particle size distribution of the rubber particles is created on a mass basis using Microtrac Bell's Nanotrac wave, and the median diameter is calculated as the average diameter. It can be measured by determining the particle size.

[Flame retardants]
The curable resin composition of the present invention can contain a flame retardant. Flame retardants include hydrated metals such as aluminum hydroxide and magnesium hydroxide, red phosphorus, ammonium phosphate, ammonium carbonate, zinc borate, zinc stannate, molybdenum compounds, bromine compounds, chlorine compounds, and phosphate esters. , phosphorus-containing polyol, phosphorus-containing amine, melamine cyanurate, melamine compound, triazine compound, guanidine compound, silicone polymer, etc. can be used. The flame retardants can be used alone or in combination of two or more.

[Organic solvent]
The organic solvent is not particularly limited, but examples include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, etc. can. More specifically, ketones such as methyl ethyl ketone, cyclohexanone, methyl butyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, and methyl carbitol. , butyl carbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, triethylene glycol monoethyl ether, and other glycol ethers; Esters such as ethyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol butyl ether acetate; ethanol, propanol, 2- Alcohols such as methoxypropanol, n-butanol, isobutyl alcohol, isopentyl alcohol, ethylene glycol, propylene glycol; Aliphatic hydrocarbons such as octane and decane; Petroleum such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha In addition to system solvents, examples include N,N-dimethylformamide (DMF), tetrachloroethylene, and turpentine oil. In addition, Swasol 1000 and Swasol 1500 manufactured by Maruzen Petrochemical Co., Ltd., Solvent #100 and Solvent #150 manufactured by Sankyo Chemical Co., Ltd., Shell Sol A100 and Shell Sol A150 manufactured by Shell Chemicals Japan, Ipsol No. 100 and Ipsol No. 150 manufactured by Idemitsu Kosan, etc. Organic solvents may also be used. The organic solvents can be used alone or in combination of two or more.

When formed into a dry film, the amount of residual solvent in the resin layer is preferably 0.1 to 10.0% by mass. When the residual solvent is 10.0% by mass or less, bumping during thermosetting is suppressed and the surface flatness becomes better. Furthermore, it is possible to prevent the melt viscosity from decreasing too much and causing the resin to flow, resulting in good flatness. When the residual solvent content is 0.1% by mass or more, particularly 0.5% or more, the fluidity during lamination is good, and the flatness and embeddability are better.

[Other ingredients]
The curable resin composition of the present invention may further contain organic fillers such as silicon powder, fluorine powder, and nylon powder, phthalocyanine blue, phthalocyanine green, iodine green, disazo yellow, crystal violet, titanium oxide, Conventionally known coloring agents such as carbon black and naphthalene black; conventionally known thickeners such as asbestos, olben, bentone, and finely divided silica; antifoaming agents and/or leveling agents such as silicone-based, fluorine-based, and polymer-based agents; , thiazole-based, triazole-based, adhesion-imparting agents such as silane coupling agents, and conventionally known additives such as titanate-based and aluminum-based additives.

The curable resin composition of the present invention may be used in the form of a dry film or in the form of a liquid. When used in liquid form, it may be one-component or two-component or more, but preferably two-component or more from the viewpoint of storage stability.

<Dry film>
The dry film of the present invention can be manufactured by applying the curable resin composition of the present invention onto a carrier film and drying it to form a resin layer as a dry coating film. A protective film can be laminated on the resin layer, if necessary.

The carrier film has a role of supporting the resin layer of the dry film, and is a film to which a curable resin composition is applied when forming the resin layer. Examples of carrier films include polyester films such as polyethylene terephthalate and polyethylene naphthalate, films made of thermoplastic resins such as polyimide films, polyamideimide films, polyethylene films, polytetrafluoroethylene films, polypropylene films, and polystyrene films; Surface-treated paper or the like can be used. Among these, polyester films can be preferably used from the viewpoints of heat resistance, mechanical strength, handleability, and the like. The thickness of the carrier film is not particularly limited, but is appropriately selected in the range of approximately 10 to 150 μm depending on the application. The surface of the carrier film on which the resin layer is provided may be subjected to a mold release treatment. Further, sputtering or copper foil may be formed on the surface of the carrier film on which the resin layer is provided.

The protective film is provided on the opposite side of the resin layer from the carrier film for the purpose of preventing dust etc. from adhering to the surface of the resin layer of the dry film and improving handling properties. As the protective film, for example, a film made of a thermoplastic resin as exemplified in the carrier film, surface-treated paper, etc. can be used, but among these, polyester film, polyethylene film, and polypropylene film are preferable. The thickness of the protective film is not particularly limited, but is appropriately selected in the range of approximately 10 to 150 μm depending on the application. The surface of the protective film on which the resin layer is provided may be subjected to a mold release treatment.

<Resin coated copper foil>
The resin-coated copper foil of the present invention has a resin layer obtained by applying the curable resin composition of the present invention to a copper foil surface of a copper foil or a carrier-coated copper foil and drying the coating.

[Copper foil with carrier]
The carrier-attached copper foil may have a structure including a carrier foil and a copper foil in this order, and the resin layer made of the curable resin composition of the present invention may be laminated so as to be in contact with the copper foil. It is preferable to use ultra-thin copper foil as the copper foil.

Examples of the carrier foil include copper foil, aluminum foil, stainless steel (SUS) foil, and a resin film whose surface is coated with metal, and copper foil is preferable. The copper foil may be an electrolytic copper foil or a rolled copper foil. The thickness of the carrier foil is usually 250 μm or less, preferably 9 to 200 μm. Note that a release layer may be formed between the carrier foil and the copper foil, if necessary.

The method of forming the copper foil is not particularly limited, but it is preferable to form an ultra-thin copper foil, and wet film forming methods such as electroless copper plating and electrolytic copper plating, dry film forming methods such as sputtering and chemical vapor deposition, and , can be formed by a combination of these. The thickness of the ultra-thin copper foil is preferably 0.1 to 7.0 μm, more preferably 0.5 to 5.0 μm, and even more preferably 1.0 to 3.0 μm.

<Cured product>
The cured product of the present invention is obtained by curing the curable resin composition of the present invention, the resin layer of the dry film of the present invention, or the resin layer of the resin-coated copper foil of the present invention.

The method of curing is not particularly limited, and any conventionally known method may be used, for example, by heating at 150 to 230°C. As a method for manufacturing a printed wiring board using a curable resin composition, for example, in the case of a dry film with a three-layer structure in which a resin layer is sandwiched between a carrier film and a protective film, printing is performed using the following method. Wiring boards can be manufactured.

That is, either the carrier film or the protective film is peeled off from the dry film, heated and laminated onto a circuit board on which a circuit pattern is formed, and then thermally cured. Thermal curing may be performed by curing in an oven or by using a hot plate press. When laminating or hot plate pressing a circuit board and the dry film of the present invention, a copper foil or a circuit board can also be laminated at the same time. A printed wiring board can be manufactured by forming a pattern or a via hole by laser irradiation or drilling at a position corresponding to a predetermined position on a circuit board and exposing the circuit wiring. At this time, if there is a component (smear) that has not been completely removed and remains on the circuit wiring in the pattern or via hole, a desmear process is performed. The remaining carrier film or protective film may be peeled off after lamination, after thermosetting, after laser processing, or after desmear processing.

In addition, when manufacturing printed wiring boards using the resin-coated copper foil of the present invention, the resin layer is laminated on the circuit board, and the copper foil is used as all or part of the wiring layer using a modified semi-additive process (MSAP) method. A circuit may be formed and a build-up wiring board may be manufactured. Alternatively, a build-up wiring board may be manufactured in which the copper foil is removed and a circuit is formed using a semi-additive process (SAP) method. Alternatively, a printed wiring board may be manufactured by direct build-up on wafer, in which lamination of resin-coated copper foil and circuit formation are alternately repeated on a semiconductor integrated circuit. Alternatively, a coreless build-up method may be used in which resin layers and conductor layers are alternately laminated without using a core substrate.

<Electronic parts>
The electronic component of the present invention has a cured product of the present invention, that is, a cured product of the curable resin composition of the present invention, a resin layer of a dry film of the present invention, or a resin layer of a resin-coated copper foil of the present invention.

Examples of electronic components include permanent protective films for printed wiring boards, and among them, solder resist layers, interlayer insulation layers, and coverlays for flexible printed wiring boards. In addition, electronic components include applications other than printed wiring boards, such as passive components such as inductors.

In addition to the above-mentioned uses, the curable resin composition of the present invention can also be suitably used for permanently filling holes in printed wiring boards, for example, filling holes such as through holes and via holes. It can also be used as a sealing material for semiconductor chips, and as a material for copper clad laminates (CCL) and prepregs.

Further, since the cured product of the curable resin composition of the present invention has excellent dielectric properties, the use of the cured product provides good transmission quality even in high frequency applications. Specific examples of high-frequency applications include substrates for millimeter-wave radar and millimeter-wave sensors for autonomous driving, mobile motherboards for high-speed communication, and SLP (Substrate-Like PCB) where circuits are formed using the modified semi-additive process (MSAP) method. ), application processors (AP) for mobile and personal computers, high multilayer substrates for base station servers and routers, substrates for antennas, and semiconductor encapsulation materials.

Furthermore, a wiring board may be formed by bonding wiring using the dry film of the present invention.

The form of the circuit forming material using the curable resin composition of the present invention is resin-coated copper foil (RCC) compatible with modified semi-additive process (MSAP) and resin-coated copper foil (RCC) compatible with semi-additive process (SAP). It may also be a build-up film.

Although the dielectric loss tangent of the cured product of the present invention is not particularly limited, according to the present invention, it is possible to obtain a cured product with a low dielectric loss tangent, for example, 0.003 or less at a frequency of 10 GHz and 23 ° C. It is also possible to set it to 0.002 or less, or even 0.001 or less.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited only to these Examples. In the following, unless otherwise specified, "parts" and "%" mean parts by mass and % by mass.

(Synthesis of (A-1) epoxy compound of formula (II) above)
A mixture of 1,3,5-tris(4-hydroxyphenyl)benzene (THPB) (354.4 g, 1 mol), epichlorohydrin (2780 g, 30 mol) and benzyltrimethylammonium chloride solution (60% solution) The reaction mixture was placed in a flask equipped with a stirrer, a thermometer, and a condenser, and the reaction mixture was heated with stirring to reflux for 1 hour, and then cooled. After cooling, the reaction mixture was placed on a water bath (50° C.) and 1 L of 3 mol/L NaOH was slowly added with stirring. After the addition, the mixture was stirred at 50° C. for 1 hour. The organic phase was separated from the mixture, placed on a water bath (50° C.) and an additional 1 L of 3 mol/L NaOH was added with stirring. Stirring was continued for an additional hour after the addition. The organic phase was separated and washed with aqueous monobasic sodium phosphate solution and then with water until neutral. The organic matter is vacuum distilled to remove water and unreacted epichlorohydrin, thereby producing 1,3,5-tris(4-glycidyloxyphenyl)benzene (A-1) represented by formula (II). I got it.

((B) Synthesis of compound having active ester group)
[Synthesis example 1]
203.0 g of isophthalic acid chloride (number of moles of acid chloride group: 2.0 moles) and 1338 g of toluene were placed in a flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer, and the system was replaced with nitrogen under reduced pressure. and dissolved. Next, 96.0 g (0.67 mol) of α-naphthol and 220 g of dicyclopentadiene phenol resin (number of moles of phenolic hydroxyl group: 1.33 mol) were charged, and the system was replaced with nitrogen under reduced pressure to dissolve them. Thereafter, 1.12 g of tetrabutylammonium bromide was dissolved, and 400 g of a 20% aqueous sodium hydroxide solution was added dropwise over 3 hours while controlling the inside of the system to 60° C. or lower while purging with nitrogen gas.

Stirring was then continued under these conditions for 1.0 hour. After the reaction was completed, the mixture was allowed to stand still for liquid separation, and the aqueous layer was removed. Furthermore, water was added to the toluene phase in which the reactants were dissolved, and the mixture was stirred and mixed for about 15 minutes, and the mixture was allowed to stand still for liquid separation to remove the aqueous layer. This operation was repeated until the pH of the aqueous layer reached 7. Thereafter, water was removed by dehydration using a decanter to obtain a compound (B-1) having an active ester in a toluene solution state with a nonvolatile content of 65%.

The ester group equivalent of the compound (B-1) having an active ester group was 223 g/mol in terms of solid content.

[Synthesis example 2]
Into a flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer, 320 g (2.0 mol) of 2,7-dihydroxynaphthalene, 184 g (1.7 mol) of benzyl alcohol, and para-toluenesulfonic acid. 5.0 g of monohydrate was charged and stirred at room temperature while blowing nitrogen. Thereafter, the temperature was raised to 150° C., and the mixture was stirred for 4 hours while distilling the generated water out of the system. After the reaction was completed, 900 g of methyl isobutyl ketone and 5.4 g of 20% aqueous sodium hydroxide solution were added to neutralize, and then the aqueous layer was removed by liquid separation, washed three times with 280 g of water, and methyl isobutyl ketone was removed under reduced pressure. The residue was removed to obtain 460 g of a benzyl-modified naphthalene compound (B-2 intermediate). The obtained benzyl-modified naphthalene compound (B-2 intermediate) was a black solid, and the hydroxyl equivalent was 180 g/equivalent.

Next, 203.0 g of isophthalic acid chloride (number of moles of acid chloride group: 2.0 mol) and 1400 g of toluene were charged into another flask equipped with a thermometer, dropping funnel, cooling tube, fractionating tube, and stirrer. The inside of the system was replaced with nitrogen under reduced pressure to dissolve it. Next, 96.0 g (0.67 mol) of α-naphthol and 240 g (mol number of phenolic hydroxyl group: 1.33 mol) of a benzyl-modified naphthalene compound (B-2 intermediate) were charged, and the inside of the system was replaced with nitrogen under reduced pressure. Dissolved. Thereafter, 0.70 g of tetrabutylammonium bromide was dissolved, and 400 g of a 20% aqueous sodium hydroxide solution was added dropwise over 3 hours while controlling the inside of the system to 60° C. or lower while purging with nitrogen gas. Stirring was then continued under these conditions for 1.0 hour. After the reaction was completed, the mixture was allowed to stand still for liquid separation, and the aqueous layer was removed. Further, water was added to the toluene layer in which the reactants were dissolved, and the mixture was stirred and mixed for 15 minutes, and the mixture was allowed to stand still for liquid separation to remove the aqueous layer. This operation was repeated until the pH of the aqueous layer reached 7. Thereafter, water was removed by dehydration using a decanter to obtain a compound (B-2) having an active ester group in a toluene solution state with a solid content of 65% by mass. The resulting active ester group-containing compound (B-2) had an ester group equivalent of 230 g/mol in terms of solid content.

<1. Preparation of curable resin composition>
Various components shown in Table 1 below were kneaded and mixed in the proportions (parts by mass) shown in Table 1 to prepare curable resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4 for producing films after curing. did. Note that the numerical values in Table 1 indicate parts by mass or % by mass (in terms of solid content).

Regarding each of the curable resin compositions, test samples were prepared as shown below, and the glass transition temperature (Tg) and dielectric loss tangent were measured and evaluated. The results are shown in Table 1.
<2. Preparation of film after curing>
Using a film applicator, the curable resin compositions of the Examples and Comparative Examples obtained above were applied onto the glossy surface of copper foil (F2-WS manufactured by Furukawa Electric Co., Ltd., 18 μm thick), and a hot air circulation method was applied. After drying in a drying oven at 90° C. for 10 minutes and then curing at 200° C. for 60 minutes, the copper foil was peeled off to produce a cured film (cured film) each having a thickness of about 40 μm.
<3. Measurement of glass transition temperature (Tg)>
Said <2. Preparation of film after curing> The sample obtained in step 1 was cut into a measurement size (3 mm x 10 mm), and the glass transition temperature (Tg) was measured using TMA Q400EM manufactured by TA Instruments. The temperature was raised from room temperature at a heating rate of 10° C./min, and the measurement was carried out twice in succession, and the glass transition temperature (Tg), which is the intersection of two tangents with different linear thermal expansion coefficients, was evaluated at the second measurement.

Evaluation of glass transition temperature was performed based on the following criteria.

◎: 180°C or more ○: Less than 180°C 175°C or more ×: Less than 175°C <4. Measurement of dielectric loss tangent (Df)>
Said <2. Preparation of film after curing> Cut out the sample obtained in measurement size (50 mm x 60 mm size), and measure the dielectric loss tangent at 23°C at 10 GHz using an SPDR dielectric resonator and a network analyzer (both manufactured by Agilent). I did it.

The dielectric loss tangent (Df) was evaluated based on the following criteria.

◎: Less than 0.003 ○: 0.003 or more and less than 0.010 ×: 0.010 or more

Details of the components in Table 1 are as follows.

(A-1): Manufactured by the above-mentioned synthesis method EPICLON (registered trademark) EXA-835LV (manufactured by DIC, a mixture of bisphenol A epoxy resin and bisphenol F epoxy resin, liquid, epoxy equivalent: 165 g/eq)
1031S (manufactured by Mitsubishi Chemical Corporation, tetraphenylethane type epoxy resin, solid, epoxy equivalent: 200g/eq)
NC-3000H (manufactured by Nippon Kayaku Co., Ltd., biphenyl novolak type epoxy resin, solid, epoxy equivalent: 290 g/eq)
B-1: Manufactured according to Synthesis Example 1 (active ester equivalent: 223 g/eq)
B-2: Manufactured according to Synthesis Example 2 (active ester equivalent: 230 g/eq)
TD-2090: Phenol novolac (manufactured by DIC)
SO-C2: Spherical silica treated with phenylaminosilane (average particle size: 0.5 μm, carbon content per unit mass 0.18) (manufactured by Admatex)
YX6954 BH30: Phenoxy resin (manufactured by Mitsubishi Chemical Corporation)
2E4MZ: 2-ethyl-4-methylimidazole*1: Ratio of (A) total amount of epoxy groups in epoxy compounds/(B) total amount of active ester groups in compounds having active ester groups in the composition

It can be seen that according to the curable resin compositions of Examples 1 to 6, cured products having both high heat resistance and low dielectric loss tangent can be obtained. In particular, in Examples 1 to 5, the dielectric loss tangent was extremely low.

Claims (8)

(A) epoxy compound,
(B) a compound having an active ester group; and (C) a curable resin composition containing an inorganic filler,
The epoxy compound (A) has the following formula (II)

Contains an epoxy compound represented by
A curable resin composition characterized in that the ratio of the total amount of epoxy groups in the epoxy compound (A) to the total amount of ester groups in the compound having an active ester group (B) is 0.2 or more and 1.2 or less. . The content of the epoxy compound represented by formula (II) relative to the total amount of the epoxy compound (A) and the active ester group-containing compound (B) is 5% by mass or more and 25% by mass or less in terms of solid content. The curable resin composition according to claim 1, characterized in that: The compound (B) having an active ester group has the following general formula (1)

(In the formula, X ₁ is each independently a group having a benzene ring or a naphthalene ring, k represents 0 or 1, and n is 0.05 to 2.5 on average of the repeating units.) The curable resin composition according to claim 1 or 2 , which is a compound comprising: The compound (B) having an active ester group has the following general formula (2):

(In formula (2), each X ₂ is independently represented by the following formula (3):

A group represented by or the following formula (4):

is a group represented by
m is an integer from 1 to 6, n is each independently an integer from 1 to 5, q is each independently an integer from 1 to 6,
In formula (3), k is each independently an integer from 1 to 5,
In formula (4), Y is a group represented by the above formula (3) (k is each independently an integer of 1 to 5), and t is each independently an integer of 0 to 5)
The curable resin composition according to claim 1 or 2 , which is a compound having a structural moiety represented by the following and whose both ends are monovalent aryloxy groups. A dry film comprising the curable resin composition according to any one of claims 1 to 4 as a resin layer. A resin-coated copper foil comprising the curable resin composition according to any one of claims 1 to 4 as a resin layer on the copper foil or the carrier-coated copper foil. A cured product of the curable resin composition according to any one of claims 1 to 4 , the resin layer of the dry film according to claim 5 , or the resin layer of the resin-coated copper foil according to claim 6 . An electronic component comprising the cured product according to claim 7 .