Resin composition

Abstract

The present invention addresses the problem of providing a resin composition having excellent varnish stability and film flexibility. [Solution] A resin composition containing (A) a cyclic phosphazene compound having a specific structure, (B) a maleimide resin, (C) a radical polymerizable compound (excluding maleimide), (E) an inorganic filler, and (F) a curing accelerator, the amount of the inorganic filler being less than or equal to 100% by mass relative to 100% by mass of non-volatile components of the resin composition, and the amount of the radical polymerizable compound being less than or equal to 100% by mass relative to 100% by mass of the non-volatile components of the resin composition. And (E) the content of the inorganic filler is 60 mass% or more.

Description

Technical Field

[0001] This invention relates to resin compositions and their cured products, resin sheets, circuit boards, and semiconductor devices. Background Technology

[0002] Circuit boards, such as printed wiring boards, are widely used in various electronic devices. As a method for manufacturing circuit boards, a method based on alternating stacking of insulating and conductive layers on an inner substrate is known. The insulating layer is formed, for example, from a cured resin composition containing a curable resin such as epoxy resin and its curing agent. To improve flame retardancy, a resin composition containing a flame retardant is sometimes used (see Patent Documents 1 and 2).

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2022-21767 Patent Document 2: Japanese Patent Application Publication No. 2021-04297. Summary of the Invention

[0004] The problem that the invention aims to solve Typically, resin compositions are sometimes stored as resin varnishes, which are liquid compositions containing solvents. The term "varnish stability," unless otherwise specified, refers to the property of less precipitation of components from the resin varnish when the resin composition is stored in its varnish state.

[0005] Additionally, a resin composition layer comprising the resin composition is formed using the resin composition. The term "film flexibility" refers to the property of being able to form a resin composition layer with excellent mechanical strength using the resin composition; more specifically, it refers to the property of being able to form a resin composition layer with excellent flexural strength or excellent tensile strength.

[0006] From the perspective of reducing transmission loss, resin compositions containing a large amount of free radical polymerizable compounds and inorganic fillers are sometimes used. However, resin compositions combining free radical polymerizable compounds, inorganic fillers, and flame retardants sometimes exhibit poor varnish stability and poor tensile strength of the cured product.

[0007] The present invention was made in view of the above-mentioned problems, and aims to provide: a resin composition with excellent varnish stability and fracture strength of the cured product; a resin sheet comprising the resin composition; a cured product of the resin composition; a circuit board comprising the cured product of the resin composition; and a semiconductor device comprising the circuit board.

[0008] Methods for solving problems The inventors conducted in-depth research to solve the aforementioned problems. As a result, they discovered that a resin composition comprising (A) a cyclic phosphazene compound, (B) a maleimide resin, (C) a free radical polymerizable compound (excluding maleimide), (E) an inorganic filler, and (F) a curing accelerator can solve the aforementioned problems, thus completing the present invention. That is, the present invention includes the following contents.

[0009] [1] A resin composition comprising (A) a cyclic phosphazene compound of formula (1) below, (B) a maleimide resin, (C) a free radical polymerizable compound (other than maleimide), (E) an inorganic filler and (F) a curing accelerator. Of which, relative to 100% by mass of the non-volatile components of the resin composition, the content of (E) inorganic filler material is 60% by mass or more. [Chemical Formula 1] (In formula (1),) R 1 and R 2 (i) Represented independently Nitro, An alkyl or alkoxy group having 1 to 8 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms, and The aryl or aryloxy group having 6 to 20 carbon atoms is optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms. any of them, or (ii) They form saturated or unsaturated cyclic structures with each other, which are optionally substituted with alkyl or carbonyl groups having 1 to 6 carbon atoms; L represents a divalent heteroatom; a and b each independently represent integers from 0 to 4; m independently represents 0 or 1; n represents an integer from 3 to 8; The structures of the repeating units are independent. [2] According to the resin composition of [1], wherein the mass ratio of (B) maleimide resin to (C) free radical polymerizable compound (excluding maleimide) (mass of (B) component / mass of (C) component) is 0.6 to 1.9; [3] The resin composition according to [1] or [2], wherein (A) the cyclic phosphazene compound is a particle having an average particle size of less than 1.5 μm; [4] The resin composition according to [1] or [2], wherein (A) the cyclic phosphazene compound is a particle having an average particle size of less than 0.8 μm; [5] The resin composition according to any one of [1] to [4], wherein (A) the cyclic phosphazene compound consists of particles having an average particle size of Da μm. (E) The average particle size of the inorganic filler is Dbμm. Da / Db is above 0.1 and below 10; [6] The resin composition according to [5], wherein Da / Db is 1.5 or less; [7] The resin composition according to any one of [1] to [6], wherein (A) the cyclic phosphazene compound has a melting point of 260°C or higher; [8] The resin composition according to any one of [1] to [7], wherein, in the case of a first dissolution test, the amount of (A) cyclic phosphazene compound dissolved is less than 0.04 g, wherein the first dissolution test is performed by ultrasonic treatment at 25°C for 10 minutes to dissolve (A) cyclic phosphazene compound in 10 g of cyclohexanone; [9] The resin composition according to any one of [1] to [8], wherein, in the case of a second dissolution test, the amount of (A) cyclic phosphazene compound dissolved is less than 0.3 g, wherein the second dissolution test is performed by ultrasonic treatment at 70°C for 10 minutes to dissolve (A) cyclic phosphazene compound in 10 g of cyclohexanone;

[10] The resin composition according to any one of [1] to [9], wherein when the resin component of the resin composition is set to 100% by mass, the content of (A) cyclic phosphazene compound is less than 5% by mass;

[11] The resin composition according to any one of [1] to

[10] , wherein when the resin component of the resin composition is set to 100% by mass, the content of (A) cyclic phosphazene compound is 0.3% by mass or more;

[12] The resin composition according to any one of [1] to

[10] , wherein when the resin component of the resin composition is set to 100% by mass, the content of (A) cyclic phosphazene compound is 0.1% by mass or more and 5% by mass or less;

[13] The resin composition according to any one of [1] to

[12] , wherein, relative to 100% by mass of the non-volatile components of the resin composition, (B) the content of maleimide resin is 1% by mass or more and 40% by mass or less;

[14] The resin composition according to any one of [1] to

[13] , wherein when the non-volatile component in the resin composition is set to 100% by mass, the content of (C) free radical polymerizable compound is 1% by mass or more and 40% by mass or less;

[15] The resin composition according to any one of [1] to

[14] , wherein when the non-volatile component in the resin composition is set to 100% by mass, the content of (E) inorganic filler material is 60% by mass or more and 90% by mass or less;

[16] The resin composition according to any one of [1] to

[15] , wherein when the non-volatile component in the resin composition is set to 100% by mass, the content of (F) curing accelerator is 0.01% by mass or more and 3.0% by mass or less;

[17] The resin composition according to any one of [1] to

[16] , wherein the resin composition comprises a ketone solvent;

[18] The resin composition according to any one of [1] to

[17] , wherein the resin composition comprises a solvent, the solvent comprising a non-aromatic high-boiling solvent that does not contain an aromatic ring in the molecule and has a boiling point of 100°C or higher;

[19] According to the resin composition of

[18] , the content of non-aromatic high-boiling solvent is 50% by mass or less relative to 100% by mass of the total amount of solvent;

[20] According to the resin composition of

[18] , the content of non-aromatic high-boiling solvent is 8% by mass or less relative to 100% by mass of the total amount of the resin composition;

[21] The resin composition according to any one of [1] to

[20] , wherein it further comprises (D) a thermoplastic resin;

[22] A resin sheet comprising a support and a resin composition layer formed thereon. The resin composition layer comprises any one of the resin compositions described in [1] to

[21] ; Cured products of the resin compositions described in any one of

[23] [1] to

[21] ;

[24] A circuit board comprising a cured form of the resin composition described in any one of [1] to

[21] ;

[25] A semiconductor device comprising the circuit board described in

[24] .

[0010] Invention Effects According to the present invention, the following can be provided: a resin composition with excellent varnish stability and film flexibility; a resin sheet comprising the resin composition; a cured product of the resin composition; a circuit board comprising the cured product of the resin composition; and a semiconductor device comprising the circuit board. Detailed Implementation

[0011] The present invention will now be described with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented in any way without departing from the scope of the claims and their equivalents.

[0012] In this specification, the term “optionally substituted” for a compound, group, or ring, unless otherwise stated, refers to both the case where the hydrogen atoms of the compound, group, or ring are not substituted by a substituent and the case where some or all of the hydrogen atoms of the compound, group, or ring are substituted by a substituent.

[0013] In this specification, the term "resin composition layer" means a layer containing a resin composition unless otherwise specified. Typically, a resin composition layer contains only a resin composition.

[0014] In this specification, unless otherwise specified, the term "cured layer" refers to a layer containing a cured resin composition. Typically, a cured layer contains only a cured resin composition.

[0015] <Summary of the Resin Composition> One embodiment of the present invention relates to a resin composition comprising (A) a cyclic phosphazene compound of formula (1) below, (B) a maleimide resin, (C) a free radical polymerizable compound (other than maleimide), (E) an inorganic filler, and (F) a curing accelerator.

[0016] [Chemical Formula 2]

[0017] (In formula (1),) R 1 and R 2 (i) Represented independently Nitro, An alkyl or alkoxy group having 1 to 8 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms, and The aryl or aryloxy group having 6 to 20 carbon atoms is optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms. any of them, or (ii) They form saturated or unsaturated cyclic structures with each other, which are optionally substituted with alkyl or carbonyl groups having 1 to 6 carbon atoms; L represents a divalent heteroatom; a and b each independently represent integers from 0 to 4; m independently represents 0 or 1; n represents an integer from 3 to 8; The structures of the repeating units are independent.

[0018] In the following description, the repeating unit shown in equation (2) below is sometimes referred to as a "phosphazene unit".

[0019] [Chemical Formula 3]

[0020] (The symbol R in equation (2)) 1 R 2 L, a, b and m have the same meaning as the corresponding symbols in equation (1).

[0021] The resin composition according to this embodiment can exhibit excellent varnish stability and film flexibility. Furthermore, a cured product with a low dielectric loss tangent can generally be obtained based on the resin composition according to this embodiment. Moreover, a cured product with a high glass transition temperature can generally be obtained based on the resin composition according to this embodiment.

[0022] <(A) Cyclic phosphazene compounds> The resin composition according to this embodiment includes a (A) cyclic phosphazene compound as component (A). The (A) cyclic phosphazene compound is represented by formula (1). The (A) cyclic phosphazene compound can generally improve the flame retardancy of the cured resin composition.

[0023] [Chemical Formula 4]

[0024] In equation (1), R 1 and R 2 Each can independently represent a nitro group, any one of (R-1) and (R-2) below; or represent (R-3) below.

[0025] (R-1): An alkyl or alkoxy group having 1 to 8 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms.

[0026] As conforming to R 1 and R 2 Examples of alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, 2-ethylhexyl, benzyl, and 2-phenylethyl. Additionally, as conforming to R... 1 and R 2Examples of alkoxy groups include: methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, 2-ethylhexoxy, benzyloxy, and 2-phenylethyloxy. Among these, R, classified as (R-1),... 1 and R 2 Preferably, it is methyl, ethyl, n-propyl, benzyl, or methoxy, and more preferably methyl or ethyl.

[0027] (R-2): An aryl or aryloxy group having 6 to 20 carbon atoms, optionally substituted with at least one group selected from alkyl and aryl groups having 1 to 6 carbon atoms.

[0028] As conforming to R 1 and R 2 Examples of aryl groups include: phenyl, methylphenyl, dimethylphenyl, ethylphenyl, ethylmethylphenyl, diethylphenyl, n-propylphenyl, isopropylphenyl, isopropylmethylphenyl, isopropylethylphenyl, diisopropylphenyl, n-butylphenyl, sec-butylphenyl, tert-butylphenyl, n-pentylphenyl, n-hexylphenyl, phenylphenyl, naphthyl, anthraceneyl, and phenanthryl. Additionally, as conforming to R... 1 and R 2 Examples of aryloxy groups include: phenyloxy, methylphenyloxy, dimethylphenyloxy, ethylphenyloxy, ethylmethylphenyloxy, diethylphenyloxy, n-propylphenyloxy, isopropylphenyloxy, isopropylmethylphenyloxy, isopropylethylphenyloxy, diisopropylphenyloxy, n-butylphenyloxy, sec-butylphenyloxy, tert-butylphenyloxy, n-pentylphenyloxy, n-hexylphenyloxy, phenylphenyloxy, naphthyloxy, anthraceneyloxy, and phenanthreneoxy. Among these, R is classified as (R-2). 1 and R 2 Preferably, it is phenyl, methylphenyl, dimethylphenyl, diethylphenyl, phenylphenyl, naphthyl, and phenyloxy, more preferably phenyl and methylphenyl.

[0029] (R-3): In R 1 and R 2 The saturated or unsaturated cyclic structures formed between the atoms, wherein the cyclic structures are optionally substituted by alkyl or carbonyl groups having 1 to 6 carbon atoms.

[0030] Examples of phosphazene units with a conforming saturated cyclic structure include the repeating unit shown in equation (2-1) and the repeating unit shown in equation (2-2).

[0031] [Chemical Formula 5] (In equations (2-1) and (2-2), the symbols L and m have the same meaning as the corresponding symbols in equation (1).

[0032] Therefore, for example, when m is 0, as examples of phosphazene units with saturated cyclic structures, the repeating units shown in equation (2-1-1) and equation (2-2-1) can be cited.

[0033] [Chemical Formula 6]

[0034] In addition, as an example of a phosphazene unit with a conforming unsaturated cyclic structure, the repeating unit shown in equation (2-3) can be cited.

[0035] [Chemical Formula 7] (In equation (2-3), the symbols L and m have the same meaning as the corresponding symbols in equation (1).

[0036] Therefore, for example, when m is 0, the repeating unit shown in equation (2-3-1) can be cited as an example of a phosphazene unit with an unsaturated cyclic structure.

[0037] [Chemical Formula 8]

[0038] In equation (1), R 1 and R 2 They can be the same or different. Additionally, multiple R... 1 They can be the same or different. Furthermore, multiple Rs... 2 They can be the same or different.

[0039] In equation (1), L represents a divalent heteroatom. An example of L is the oxygen atom.

[0040] In equation (1), a and b each independently represent integers from 0 to 4. Specifically, a represents the substituent R. 1 The quantity is typically 0 or more, typically 4 or less, and preferably 2 or less. Additionally, b represents the substituent R. 2 The quantity is usually above 0, usually below 4, and preferably below 2.

[0041] In equation (1), m independently represents 0 or 1. Preferably, m is 0.

[0042] As symbols a, b, R 1 R 2Examples of combinations of L and m can be found in Table 1 below. Among them, combinations 1, 2 and 3 are preferred, and combinations 1 and 2 are more preferred.

[0043] [Table 1] [Table 1. Examples of symbol combinations]

[0044] In formula (1), n ​​represents an integer from 3 to 8. Specifically, n is usually 3 or more, usually 8 or less, and preferably 4 or less. In formula (1), n ​​represents the number of phosphazene units shown in formula (2). Therefore, the cyclic phosphazene compound (A) shown in formula (1) can be a cyclic phosphazene compound with n=3 (trimer), a cyclic phosphazene compound with n=4 (tetramer), a cyclic phosphazene compound with n=5 (pentamer), a cyclic phosphazene compound with n=6 (hexamer), a cyclic phosphazene compound with n=7 (heptamer), or a cyclic phosphazene compound with n=8 (octamer).

[0045] In formula (1), n ​​is preferably small. Therefore, when using two or more (A) cyclic phosphazene compounds with different n values, it is preferable to use a large quantity of compounds with smaller n. In a preferred example, the amount of compounds with n of 3 or 4 (i.e., trimers and tetramers) is 95% by mass or more relative to 100% of the total amount of (A) cyclic phosphazene compounds. In a further preferred example, the content of compounds with n of 3 (i.e., trimers) is 95% by mass or more relative to 100% of the total amount of (A) cyclic phosphazene compounds.

[0046] In formula (1), the structures of the phosphazene units shown in formula (2) are independent. Therefore, the n phosphazene units contained in one molecule of (A) cyclic phosphazene compound can have the same structure or different structures. Thus, (A) cyclic phosphazene compound can be a compound in which all phosphazene units are the same, or it can be a compound in which two or more phosphazene units have different structures.

[0047] Specific examples of (A) cyclic phosphazene compounds include: any one of the following: a cyclic triphosphazene compound with n=3 in formula (1), a cyclic tetraphosphazene compound with n=4 in formula (1), a cyclic pentaphosphazene compound with n=5 in formula (1), a cyclic hexaphosphazene compound with n=6 in formula (1), a cyclic heptaphosphazene compound with n=7 in formula (1), or a cyclic octaphosphazene compound with n=8 in formula (1), and is a, b, R. 1 R 2 L and m are compounds that are combinations of those in Table 1 above.

[0048] In these specific examples, the phosphazene units contained in one molecule may be different, but are preferably the same. In the preferred specific examples, a, b, and R in formula (2) represent the phosphazene units.1 R 2 The combination of L and m is the same in any phosphazene unit contained in a molecule. Therefore, as a specific example of a preferred (A) cyclic phosphazene compound, the compounds shown in formulas (1-1) to (1-19) below can be cited. In formulas (1-1) to (1-19), n is synonymous with that in formula (1).

[0049] [Chemical Formula 9]

[0050] [Chemical Formula 10]

[0051] In the specific examples described above, it is preferred to be a cyclotriphosphazene compound of formula (1) with n=3 or a cyclotetraphosphazene compound of formula (1) with n=4, and the compound is a combination of Examples 1, 2 or 3; it is further preferred to be a cyclotriphosphazene compound of formula (1) with n=3 and the compound is a combination of Examples 1 or 2. Therefore, it is preferred to be a compound of formulas (1-1) to (1-3) with n=3 or 4; it is further preferred to be a compound of formulas (1-1) to (1-2) with n=3.

[0052] (A) Cyclic phosphazene compounds can be used alone or in combination of two or more.

[0053] (A) Cyclic phosphazene compounds can have stereoisomers. For example, a cyclic triphosphazene compound with n=3 in formula (1) and which is the compound of Combination Example 1 (i.e., the compound shown in formula (1-1)) is represented by the following formula (1-1-1) if it is shown as having 3 phosphazene units.

[0054] [Chemical Formula 11]

[0055] The compound shown in formula (1-1-1) can have diastereomers. Therefore, when this compound is manufactured, the compound shown in formula (1-1-1) can be obtained as a mixture of these diastereomers. Specifically, the compound shown in formula (1-1-1) is sometimes obtained as a mixture of the cis-cis-cis type compound shown in formula (1-1-2) below (hereinafter sometimes referred to as "cis type") and the trans-cis-trans type compound shown in formula (1-1-3) below (hereinafter referred to as "trans type") in the stereoconformation of adjacent phosphazene units.

[0056] [Chemical Formula 12]

[0057] Such mixtures of diastereomers can be used directly as a mixture, or the cis and trans forms can be separated and used as individual compounds of each type. Examples of separation methods include, for instance, a combination of separation and filtration utilizing solubility in solvents such as toluene, solvent extraction, recrystallization, and separation using column chromatography.

[0058] Furthermore, (A) cyclic phosphazene compounds in formula (1) with n being 4 or more can have stereoisomers having multiple diastereomers and enantiomers. These stereoisomers can be used as mixtures containing multiple stereoisomers, or they can be separated and used as single compounds.

[0059] (A) Cyclic phosphazene compounds can be manufactured, for example, by the method described in Japanese Patent Application Publication No. 2022-21767. Alternatively, (A) cyclic phosphazene compounds can also be purchased commercially. Examples of commercially available (A) cyclic phosphazene compounds include "FP-72TP" (Formula (1-1)) and "B" (Formula (1-19)) manufactured by Fushimi Manufacturing Co., Ltd.

[0060] (A) The cyclic phosphazene compound has a melting point preferably above 260°C, more preferably above 270°C, and even more preferably above 280°C. (A) There is no particular upper limit to the melting point of the cyclic phosphazene compound; for example, it can be below 500°C, below 400°C, or below 350°C. (A) The melting point of the cyclic phosphazene compound can be determined using a differential scanning calorimeter, heating from 25°C to 500°C at a heating rate of 20°C / min. (A) The melting point of the cyclic phosphazene compound can be determined using a differential scanning calorimeter, heating from 25°C to 500°C at a heating rate of 20°C / min.

[0061] (A) The cyclic phosphazene compound preferably exhibits specific solubility in cyclohexanone. The solubility of (A) the cyclic phosphazene compound in cyclohexanone can be determined, for example, by performing a first dissolution test, in which (A) the cyclic phosphazene compound is dissolved in 10g of cyclohexanone using ultrasonic treatment at 25°C for 10 minutes. Specifically, the amount of (A) the cyclic phosphazene compound dissolved in cyclohexanone after performing the first dissolution test is preferably 0.04g or less, more preferably 0.03g or less, and even more preferably 0.02g or less. The lower limit can be 0.00g or greater than 0.00g.

[0062] The first dissolution test of the (A) cyclic phosphazene compound can be performed by the following method: Add 0.5 g of the (A) cyclic phosphazene compound to 10 g of cyclohexanone, and sonicate for 10 minutes while heating at 25°C (the test temperature for the first dissolution test) to dissolve the (A) cyclic phosphazene compound. After the added (A) cyclic phosphazene compound has completely dissolved in cyclohexanone, add another 0.5 g of the (A) cyclic phosphazene compound, and repeat the sonication for 10 minutes. Continue until the (A) cyclic phosphazene compound no longer dissolves in cyclohexanone and precipitates are observed; the cumulative amount added before this point can be considered the amount of (A) cyclic phosphazene compound dissolved in cyclohexanone. Specifically, the first dissolution test can be performed by the method described in the examples below.

[0063] The solubility of (A) cyclic phosphazene compound in cyclohexanone can be determined, for example, by performing a second dissolution test, in which (A) cyclic phosphazene compound is dissolved in 10g of cyclohexanone by ultrasonic treatment at 70°C for 10 minutes. Specifically, the amount of (A) cyclic phosphazene compound dissolved in cyclohexanone after performing the second dissolution test is preferably 0.3g or less, more preferably 0.2g or less, and even more preferably 0.1g or less. The lower limit can be 0g or greater than 0g.

[0064] (A) The second dissolution test of the cyclic phosphazene compound can be performed using the same method as the first dissolution test, except that the heating temperature during ultrasonic treatment is changed from 25°C to 70°C. Specifically, the second dissolution test can be performed using the method described in the examples below.

[0065] When using a (A) cyclic phosphazene compound whose solubility differs little from that measured in the first and second dissolution tests described above, the stability of the varnish can be improved particularly effectively. Specifically, as described below, solvents, such as cyclohexanone, have high boiling points and are capable of readily dissolving free radical polymerizable compounds. When the (A) cyclic phosphazene compound has low solubility in the solvent, and when the difference in solubility of the (A) cyclic phosphazene compound due to dissolution temperature is small, the precipitation of the (A) cyclic phosphazene compound is suppressed after storage of the resin varnish containing the solvent, thus improving the stability of the varnish particularly effectively.

[0066] Preferably, the difference between the amount of solubility measured in the first dissolution test and the amount of solubility measured in the second dissolution test is small. Specifically, the range of the above-mentioned difference in solubility is preferably 0.30 g or less, more preferably 0.20 g or less, and even more preferably 0.10 g or less. The lower limit can be 0.00 g or greater than 0.00 g. When the difference in solubility is within the above range, the varnish stability of the resin composition can be improved particularly effectively.

[0067] (A) Cyclic phosphazene compounds are typically included in the resin composition in a particulate state that is incompatible with resin components other than (A) cyclic phosphazene compounds, and are included in the cured product in a form that maintains this particulate state.

[0068] (A) The average particle size of the cyclic phosphazene compound particles is preferably 1.5 μm or less, more preferably 1.2 μm or less, and even more preferably 1.0 μm or less. The lower limit is not particularly limited, and for example, it can be 0.05 μm or more, 0.1 μm or more, 0.2 μm or more, etc. When the average particle size of the cyclic phosphazene compound particles is within the above-mentioned range, the resin composition according to this embodiment can be applied to a circuit board with small-pitch circuit wiring. When the average particle size of the cyclic phosphazene compound particles is within the above-mentioned range, the resin composition according to this embodiment further improves the varnish stability, thus suppressing the increase in the particle size of (A) cyclic phosphazene compounds even after long-term storage. Therefore, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage. Generally speaking, if the average particle size of the components in a resin varnish decreases, the particles tend to aggregate and precipitate, leading to a decrease in varnish stability. However, after conducting research, the inventors unexpectedly discovered that the varnish stability of the resin composition according to this embodiment is particularly improved when the average particle size of the (A) cyclic phosphazene compound particles is reduced. Specifically, the average particle size of the (A) cyclic phosphazene compound particles is more preferably 0.8 μm or less, 0.6 μm or less, or 0.5 μm or less. Thus, by reducing the average particle size of the (A) cyclic phosphazene compound particles, the resin composition according to this embodiment is particularly suitable for circuit boards with small-pitch circuit wiring, both before and after storage.

[0069] (A) The maximum particle size of the cyclic phosphazene compound is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 12 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, or 6 μm or less. The lower limit is not particularly limited, and for example, it can be 0.1 μm or more, 0.5 μm or more, 1 μm or more, etc. (A) When the maximum particle size of the cyclic phosphazene compound is within the above-mentioned range, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring. Furthermore, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage.

[0070] The average and maximum particle sizes of (A) cyclic phosphazene compounds can be determined using laser diffraction / scattering based on the Mie scattering theory. Specifically, the particle size distribution of (A) cyclic phosphazene compounds can be prepared on a volume basis using a laser diffraction-scattering particle size distribution measuring device. Furthermore, the median particle size D50 of this particle size distribution can be used as the average particle size, and the maximum particle size D100 of this particle size distribution can be used as the maximum particle size. The particle size distribution of (A) cyclic phosphazene compounds can be determined using the same method as the particle size distribution of (E) inorganic filler materials.

[0071] When the average particle size of the (A) cyclic phosphazene compound particles is set as Da, and the average particle size of the (E) inorganic filler material is set as Db, the ratio of Da to Db (Da / Db) is preferably 10 or less, more preferably 5 or less, further preferably 3 or less or 2 or less, particularly preferably 1.5 or less or 1.2 or less, and preferably 0.1 or more, more preferably 0.2 or more, and further preferably 0.3 or more. When the ratio of the average particle size Da of the (A) cyclic phosphazene compound particles to the average particle size Db of the (E) inorganic filler material (Da / Db) is within the above-mentioned range, the resin composition according to this embodiment can preferably be applied to a circuit board with small-pitch circuit wiring. When Da / Db is within the above-mentioned range, the varnish stability of the resin composition according to this embodiment is further improved, so the precipitation of components of the resin composition (resin varnish) can be suppressed even after long-term storage. Therefore, the resin composition according to this embodiment can be applied to circuit boards with small-pitch circuit wiring not only before storage but also after storage, and is therefore preferred.

[0072] Relative to 100% by mass of the non-volatile components of the resin composition, the content of (A) cyclic phosphazene compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less or 1% by mass or less. When the content of (A) cyclic phosphazene compound is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally have particularly good dielectric loss tangent and glass transition temperature.

[0073] It should be noted that "non-volatile components" refers to components in the resin composition other than the organic solvents described later.

[0074] Relative to 100% by mass of the resin component in the resin composition, the content of (A) cyclic phosphazene compound is preferably 0.3% by mass or more, more preferably 0.6% by mass or more, even more preferably 1% by mass or more, preferably less than 5% by mass, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the content of (A) cyclic phosphazene compound is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the dielectric loss tangent and glass transition temperature of the cured resin composition are generally particularly good.

[0075] It should be noted that "resin components" refers to the components other than the inorganic fillers described later among the non-volatile components constituting the resin composition.

[0076] When the total amount of the maleimide resin, free radical polymerizable resin, and thermoplastic resin described later in the resin composition is set to 100% by mass, the content of (A) cyclic phosphazene compound is preferably 0.3% by mass or more, more preferably 0.6% by mass or more, even more preferably 1% by mass or more, preferably less than 5% by mass, more preferably 4% by mass or less, and even more preferably 3% by mass or less. When the content of (A) cyclic phosphazene compound is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally achieve particularly good dielectric loss tangent and glass transition temperature.

[0077] As described above, (A) the cyclic phosphazene compound can be contained in the resin composition in particulate form, and therefore it is preferable to use it in a specific content ratio relative to (E) the inorganic filler material, which is also contained in the resin composition in particulate form. Specifically, the content of (A) the cyclic phosphazene compound relative to 100% by mass of (E) the inorganic filler material is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, further preferably 2% by mass or less, or 1% by mass or less.

[0078] <(B) Maleimide Resin> The resin composition involved in this embodiment includes maleimide resin as component (B). (B) Maleimide resin refers to a resin containing one or more, preferably two or more, maleimide groups (2,5-dihydro-2,5-dioxo-1H-pyrrole-1-yl) in one molecule. (B) Maleimide resin can undergo free radical polymerization reaction between the maleimide resins in (B). (B) Maleimide resin can be used alone or in combination of two or more.

[0079] Examples of (B) maleimide resins include aromatic maleimide resins having maleimide groups directly bonded to an aromatic ring, and aliphatic maleimide resins having maleimide groups directly bonded to an aliphatic group. The maleimide resin may contain only aromatic maleimide resins, only aliphatic maleimide resins, or a combination of aromatic and aliphatic maleimide resins. Preferably, the (B) maleimide resin contains aromatic maleimide resins.

[0080] Furthermore, (B) the maleimide resin is preferably a resin containing a specific molecular backbone. Examples of preferred molecular backbones include, for instance, alicyclic backbones. Among alicyclic backbones, maleimide resins containing an indane backbone are particularly preferred.

[0081] As a preferred example of (B) maleimide resin, a maleimide resin containing a partial structure shown in formula (B1) can be cited. Generally, the maleimide resin containing the partial structure shown in formula (B1) is an aliphatic maleimide resin. Furthermore, the maleimide resin containing the partial structure shown in formula (B1) preferably has 2 or more maleimide groups per molecule, more preferably 2.

[0082] [Chemical Formula 13]

[0083] (In formula (B1), ring B) bIndicates an optional aliphatic hydrocarbon ring with substituents; i b and j b Each of them independently represents an integer greater than or equal to 0 or 1, and i b and j b The total is 6 or more; * indicates a bonding site.

[0084] In equation (B1), ring B b This indicates an aliphatic hydrocarbon ring with optional substituents. The aliphatic hydrocarbon ring can be a saturated aliphatic hydrocarbon ring or an unsaturated aliphatic hydrocarbon ring. Furthermore, the aliphatic hydrocarbon ring can be a monocyclic aliphatic hydrocarbon ring having one ring or a polycyclic aliphatic hydrocarbon ring having multiple rings. The number of carbon atoms in the aliphatic hydrocarbon ring is preferably 4 or more, more preferably 5 or more, more preferably 14 or less, more preferably 10 or less, and even more preferably 6 or less.

[0085] In the above, ring B b The aliphatic hydrocarbon ring is preferably a monocyclic aliphatic hydrocarbon ring, and more preferably a monocyclic saturated aliphatic hydrocarbon ring. Examples of monocyclic saturated aliphatic hydrocarbon rings include monocyclic alkane rings such as cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, and cyclooctane ring, with cyclohexane ring being the most preferred.

[0086] As ring B b The aliphatic hydrocarbon ring may optionally contain substituents, such as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. Alkyl and alkenyl groups are preferred, and alkyl groups are more preferred.

[0087] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0088] The alkyl group can be a straight-chain, branched, or cyclic monovalent aliphatic saturated hydrocarbon group. The alkyl group preferably has 1 to 14 carbon atoms, more preferably 1 to 6, and even more preferably 1 to 3. Examples of alkyl groups include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, tert-pentyl, hexyl, isohexyl, heptyl, isohexyl, octyl, isooctyl, tert-octyl, cyclopentyl, cyclohexyl, and cyclohexylmethyl.

[0089] The alkenyl group can be a straight-chain, branched, or cyclic monovalent aliphatic unsaturated hydrocarbon group having at least one carbon-carbon double bond. The alkenyl group preferably has 2 to 14 carbon atoms, more preferably 2 to 6, and even more preferably 2 or 3. Examples of alkenyl groups include: vinyl, propenyl (allyl, 1-propenyl, isopropenyl), butenyl (1-butenyl, crotonyl, methylallyl, isocrotonyl, etc.), pentenyl (1-pentenyl, etc.), hexenyl (1-hexenyl, etc.), heptenyl (1-heptenyl, etc.), octenyl (1-octenyl, etc.), cyclopentenyl (2-cyclopentenyl, etc.), and cyclohexenyl (3-cyclohexenyl, etc.).

[0090] The aryl group can be a monovalent aromatic hydrocarbon group formed by removing one hydrogen atom from an aromatic hydrocarbon. The number of carbon atoms in the aryl group is preferably 6 to 14, more preferably 6 to 10. Examples of aryl groups include phenyl, 1-naphthyl, and 2-naphthyl.

[0091] The aralkyl group can be an alkyl group substituted with one or more (preferably one) aryl groups. The number of carbon atoms in the aralkyl group is preferably 7 to 15, more preferably 7 to 11. Examples of aralkyl groups include benzyl, phenethyl, hydrogenated cinnamyl, α-methylbenzyl, α-cumyl, 1-naphthylmethyl, 2-naphthylmethyl, etc.

[0092] In equation (B1), i b and j b Each can independently represent an integer greater than or equal to 0 or 1. Additionally, i b and j b The total is typically 6 or more, preferably 8 or more, and more preferably 10 or more. b and j b Preferably, it is an integer from 0 to 20, more preferably an integer from 1 to 20, and even more preferably an integer from 5 to 10. b and j b They can be the same or different. Where i b and j b The preferred value is 8.

[0093] As an example of a maleimide resin containing a partial structure as shown in formula (B1), a maleimide resin as shown in formula (B2) can be cited below.

[0094] [Chemical Formula 14]

[0095] (In formula (B2), R) b10 Each substituent is represented independently; cyclic C b Each independently represents an aromatic ring optionally having substituents; D b1 and D b2 Each independently represents a single bond, -C(R)x -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, -NHCO-, -COO- or -OCO-; R x Each can independently represent a hydrogen atom or an alkyl group; c b Each can independently represent 0 or 1; d b Each can independently represent an integer greater than or equal to 0 or 1; e b Each can independently represent 0, 1, or 2; n b Represents integers of 0 or higher; other symbols are as described above. Regarding c b unit, d b Unit and n b Units, individually, each unit can be the same or different.

[0096] In equation (B2), R b10 Each substituent is represented independently. As R b10 Examples of substituents shown include halogen atoms, alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkyl-oxy groups, alkenyl-oxy groups, aryl-oxy groups, and aralkyl-oxy groups.

[0097] In equation (B2), ring C b Each of the terms independently represents an aromatic ring optionally having substituents. The aromatic ring is preferably an aromatic carbon ring. The aromatic ring is preferably a 5- to 14-membered aromatic ring, more preferably a 6- to 14-membered aromatic ring, and even more preferably a 6- to 10-membered aromatic ring. Examples of aromatic rings include benzene rings, naphthalene rings, anthracene rings, phenanthrene rings, etc., more preferably benzene rings or naphthalene rings, and even more preferably benzene rings.

[0098] As ring C b The aromatic ring may optionally contain substituents, such as halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. Alkyl groups are preferred.

[0099] In equation (B2), D b1 and D b2 Each independently represents a single bond, -C(R) x -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, -NHCO-, -COO- or -OCO-, preferably single bonds, -C(R x )2- or -O-, more preferably -O-. R x Each can be independently represented by a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group.

[0100] In equation (B2), c b Each can independently represent 0 or 1.

[0101] In equation (B2), d b Each of the integers can independently represent 0 or 1 or higher, preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and even more preferably 0 or 2.

[0102] In equation (B2), e b Each can be independently represented as 0, 1, or 2, preferably 0.

[0103] In equation (B2), n b Represents an integer of 0 or higher, preferably an integer from 0 to 10.

[0104] As an example of the partial structure shown in the following formula (B3) contained in formula (B2), the partial structures shown in formulas (b-1) to (b-3) described later can be cited.

[0105] [Chemical Formula 15]

[0106] [Chemical Formula 16]

[0107] (In the formula, * indicates the bonding site).

[0108] Commercially available maleimide resins containing a portion of the structure shown in formula (B1) include, for example, "BMI-689", "BMI-1500", "BMI-1700", "BMI-3000", and "BMI-3000J" manufactured by Designer Molecules Inc.; and "SLK-1500-T80" and "SLK-6895-T90" manufactured by Shin-Etsu Chemical Co., Ltd.

[0109] As another preferred example of a maleimide resin, the maleimide resin shown in formula (B4) can be cited.

[0110] [Chemical Formula 17]

[0111] (In formula (B4), R) b21 and R b22 Each independently represents a hydrogen atom or an alkyl group; ring E b Ring F b and ring G b Each independently represents an aromatic ring optionally having substituents; Z b1 Each independently represents a single bond, -C(R) z -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-; R zEach can independently represent a hydrogen atom or an alkyl group; f b Represents an integer greater than or equal to 1; g b Each can independently represent 0 or 1; h b Each can independently represent 0, 1, 2, or 3. f b Unit and h b Each unit can be the same or different.

[0112] In equation (B4), R b21 and R b22 Each of these elements independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group. In one example, R is more preferably used. b21 and R b22 Both are hydrogen atoms. In another example, R is more preferred. b21 and R b22 Both are methyl groups. Furthermore, in another example, R is more preferred. b21 and R b22 One of them is a hydrogen atom, and the other is a methyl group.

[0113] In equation (B4), ring E b Ring F b and ring G b Each independently represents an aromatic ring optionally having substituents. As ring E b Ring F b and ring G b Substituents in the ring can be exemplified by: halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-aryl-alkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) b Ring F b and ring G b Preferably, the benzene ring is optionally substituted, more preferably a benzene ring optionally substituted with a group selected from alkyl, aryl, and aralkyl groups. In one example, ring E b Ring F b and ring G b Further preferred is an unsubstituted benzene ring. Alternatively, in another example, ring E... b Preferably, the benzene ring is substituted with an alkyl group such as ethyl, which may optionally be substituted with an alkyl-aryl-alkyl group such as ethylphenylethyl; ring F b and ring G b Further preferred are benzene rings optionally substituted with alkyl groups such as ethyl.

[0114] In equation (B4), Z b1 Each independently represents a single bond, -C(R) z -2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-, preferably single bonds or -C(R) z)2-, more preferably a single bond. R z Each can be independently represented by a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group.

[0115] In equation (B4), f b It represents an integer greater than or equal to 1, preferably an integer from 1 to 100, and more preferably an integer from 1 to 10.

[0116] In equation (B4), g b Each can be independently represented as 0 or 1, preferably 1.

[0117] In equation (B4), h b Each can be independently represented as 0, 1, 2 or 3, preferably 0, 1 or 2, more preferably 0 or 1, and even more preferably 1.

[0118] Commercially available products of maleimide resin as shown in formula (B4) include, for example, "MIR-3000-70MT" and "MIR-5000-60T" manufactured by Nippon Kayaku Co., Ltd.

[0119] As another preferred example of maleimide resin, maleimide resin represented by formula (B5) can be cited.

[0120] [Chemical Formula 18]

[0121] (In formula (B5), R) b30 Each independently represents an alkyl group; cyclic H b and Ring I b Each independently represents an aromatic ring optionally having substituents; m b Represents an integer greater than or equal to 1. m b Each unit can be the same or different.

[0122] In equation (B5), R b30 Each can be independently represented as an alkyl group, preferably a methyl group.

[0123] In equation (B5), ring H b Each independently represents an aromatic ring optionally having substituents. As ring H b Substituents in the ring can be, for example, halogen atoms, alkyl, alkenyl, aryl, aralkyl, alkyl-oxy, alkenyl-oxy, aryl-oxy, aralkyl-oxy, etc. The ring H... b Preferably, the benzene ring has optional substituents, more preferably, the benzene ring is optionally alkyl-substituted, and even more preferably, the benzene ring is alkyl-substituted.

[0124] In equation (B5), ring I bEach independently represents an aromatic ring optionally having substituents. As ring I b Substituents in the ring can be exemplified by: halogen atoms, alkyl groups, alkenyl groups, aryl groups, aralkyl groups, alkyl-oxy groups, alkenyl-oxy groups, aryl-oxy groups, aralkyl-oxy groups, etc. (Ring I) b Preferably, the benzene ring has optional substituents, more preferably, it is a benzene ring optionally substituted with an alkyl group, and even more preferably, it is an unsubstituted benzene ring.

[0125] In equation (B5), m b It represents an integer greater than or equal to 1, preferably an integer from 1 to 20.

[0126] The maleimide resin shown in formula (B5) can be manufactured, for example, by the method described in or based on the Japanese Invention Association Publication No. 2020-500211.

[0127] (B) The maleimide equivalent of the maleimide resin is preferably 30 g / eq. or more, more preferably 75 g / eq. or more, even more preferably 150 g / eq. or more, even more preferably 200 g / eq. or more, even more preferably 250 g / eq. or more, even more preferably 300 g / eq. or more, preferably 2500 g / eq. or less, more preferably 2000 g / eq. or less, even more preferably 1500 g / eq. or less, even more preferably 1000 g / eq. or less, even more preferably 500 g / eq. or less. The maleimide equivalent indicates the mass of resin per 1 equivalent of maleimide groups.

[0128] (B) The weight average molecular weight of the maleimide resin is preferably 100 or more, more preferably 150 or more, even more preferably 200 or more, even more preferably 400 or more, even more preferably 500 or more, even more preferably 600 or more, preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 3,000 or less.

[0129] (B) The content of maleimide resin relative to 100% by mass of the non-volatile components of the resin composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. When the content of maleimide resin is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally have particularly good dielectric loss tangent, glass transition temperature and surface roughness.

[0130] <(C) Free radical polymerizable compounds (excluding maleimide)> The resin composition of the present invention comprises a free radical polymerizable compound as component (C). The free radical polymerizable compound as component (C) typically contains non-aromatic carbon-carbon unsaturated bonds. Therefore, a resin containing polymerizable unsaturated groups can be used as the free radical polymerizable compound (C). However, the (B) maleimide resin described above is not included in the (C) free radical polymerizable compound. The (C) free radical polymerizable compound preferably has two or more polymerizable unsaturated groups.

[0131] Examples of (C) radical polymerizable compounds include (meth)acrylic acid-based free radical polymerizable compounds, styrene-based free radical polymerizable compounds, and allyl-based free radical polymerizable compounds. A single (C) radical polymerizable compound can be used alone, or two or more can be used in combination.

[0132] As a (meth)acrylic acid-based free radical polymerizable compound, a resin having one or more, preferably two or more, acryloyl and / or methacryloyl groups in one molecule can be used. Examples of (meth)acrylate-based free radical polymerizable compounds include, for example, low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylate compounds such as cyclohexane-1,4-diethanol di(meth)acrylate, cyclohexane-1,3-diethanol di(meth)acrylate, tricyclodecane-diethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxanediol di(meth)acrylate, 3,6-dioxane-1,8-octanediol di(meth)acrylate, etc. Low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylate compounds such as glycol di(meth)acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, etc.; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylate compounds such as tri(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tri(2-hydroxyethyl)isocyanurate tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, etc.; high molecular weight (molecular weight greater than 1000) acrylate compounds such as (meth)acrylate-modified polyphenylene ether resin, etc. Here, the term "(meth)acrylic acid" includes acrylic acid, methacrylic acid, and combinations thereof. Additionally, the term "(meth)acrylate" includes acrylates, methacrylates, and combinations thereof. Examples of commercially available (meth)acrylic acid-based free radical polymerizable compounds include: "A-DOG" (dioxanediol diacrylate) manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; "DCP-A" (tricyclodecanediethanol diacrylate), "DCP" (tricyclodecanediethanol dimethacrylate), and "BPE-1300N" (ethoxylated bisphenol A dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd.; "KAYARAD R-684" (tricyclodecanediethanol diacrylate) and "KAYARAD R-604" (dioxanediol diacrylate) manufactured by Nippon Kayaku Co., Ltd.; and "SA9000" and "SA9000-111" (methacrylic acid-modified polyphenylene ether), etc., manufactured by SABIC.

[0133] As styrene-based free radical polymerizable compounds, resins having one or more, preferably two or more, vinyl groups directly bonded to aromatic carbon atoms in one molecule can be used. Examples of styrene-based free radical polymerizable compounds include, for example, low molecular weight (molecular weight less than 1000) styrene-based compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl) ether; and high molecular weight (molecular weight 1000 or more) styrene-based compounds such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer. Commercially available styrene-based free radical polymerizable compounds include, for example: "ODV-XET(X03)", "ODV-XET(X04)", and "ODV-XET(X05)" (styrene-divinylbenzene copolymer) manufactured by Nippon Steel Chemical Materials Co., Ltd., and "OPE-2St1200" and "OPE-2St 2200" (vinyl benzyl modified polyphenylene ether resin) manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0134] As allyl-based free radical polymerizable compounds, resins having one or more, preferably two or more, allyl groups in one molecule can be used. Examples of allyl-based free radical polymerizable compounds include: aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenedicarboxylate; isocyanurate allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; aromatic allyl compounds containing ethers such as 1,3,5-triallyl etherbenzene; and allylsilane compounds such as diallyl diphenylsilane. Commercially available allyl-based free radical polymerizable compounds include, for example: TAIC (1,3,5-triallyl isocyanurate) manufactured by Nippon Chemical Co., Ltd.; DAD (diallyl biphenylcarboxylate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; TRIAM-705 (triallyl trimellitate) manufactured by Fujifilm and Kouichi Pharmaceutical Co., Ltd.; DAND (2,3-diallyl naphtholic acid) manufactured by Nisshoku Techno Fine Chemical Co., Ltd.; and ALP-d (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Chemical Industry Co., Ltd.

[0135] It should be noted that the resin composition of the present invention, as a (C) free radical polymerizable compound, may or may not contain an allyl phenolic compound (i.e., a compound containing an allyl group and a phenolic hydroxyl group).

[0136] When the non-volatile component in the resin composition is set to 100% by mass, the content of the free radical polymerizable compound (C) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. When the content of the free radical polymerizable compound (C) is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally be made to have particularly good dielectric loss tangent and glass transition temperature.

[0137] Based on mass, the content ratio of (B) maleimide resin to (C) free radical polymerizable compound ((B) maleimide resin / (C) free radical polymerizable compound) is preferably 0.1 or more, more preferably 0.2 or more, further preferably 0.3 or more, particularly preferably 0.6 or more, preferably 5.0 or less, more preferably 4.0 or less, further preferably 3.0 or less, particularly preferably 1.9 or less, or 1.8 or less. When the content ratio ((B) maleimide resin / (C) free radical polymerizable compound) is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally be made to have particularly good dielectric loss tangent and glass transition temperature. It should be noted that, based on quality standards, the ratio of (B) maleimide resin to (C) free radical polymerizable compound ((B) maleimide resin / (C) free radical polymerizable compound) can be 0.7 or more, 0.9 or more, or 1.1 or more; alternatively, it can be 1.7 or less, 1.5 or less, or 1.3 or less.

[0138] <(D) Thermoplastic Resin> The resin composition involved in this embodiment may include (D) a thermoplastic resin as an arbitrary component. Examples of thermoplastic resins include: phenoxy resins, polyimide resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyamide-imide resins, polyether-imide resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, polyetheretherketone resins, polyester resins, etc. (F) One type of thermoplastic resin may be used alone, or two or more types may be used in combination.

[0139] Examples of phenoxy resins include those having one or more skeletons selected from the following: bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, phenolic skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal group of the phenoxy resin can be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include: Mitsubishi Chemical's "1256" and "4250" (both phenoxy resins containing a bisphenol A backbone); Mitsubishi Chemical's "YX8100" (a phenoxy resin containing a bisphenol S backbone); Mitsubishi Chemical's "YX6954" (a phenoxy resin containing a bisphenol acetophenone backbone); Nippon Steel Chemical Materials' "FX280" and "FX293"; and Mitsubishi Chemical's "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30", etc.

[0140] Specific examples of polyimide resins include: "PIAD200" manufactured by Arakawa Chemical Co., Ltd., "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "RIKACOAT SN20" and "RIKACOAT PN20" manufactured by Shin Nippon Rika Co., Ltd. Other specific examples of polyimide resins include: linear polyimide resins obtained by reacting difunctional hydroxyl-terminated polybutadiene, diisocyanate compounds, and tetrabasic anhydrides (the polyimide resin described in Japanese Patent Application Publication No. 2006-37083), and modified polyimide resins containing a polysiloxane backbone (the polyimide resins described in Japanese Patent Application Publication Nos. 2002-12667 and 2000-319386, etc.).

[0141] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include the S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemicals Co., Ltd.

[0142] Examples of polystyrene-based resins include: unmodified polystyrene resins, modified polystyrene resins containing oxazoline groups, and styrene block copolymers. Examples of styrene block copolymers include: styrene-isoprene-styrene block copolymers (SIS resin), styrene-ethylene / butene-styrene block copolymers (SEBS resin), styrene-ethylene / propylene-styrene block copolymers (SEPS resin), styrene-butadiene-styrene block copolymers (SBS resin), and styrene-isobutylene-styrene block copolymers (SIBS resin). Specific examples of polystyrene-based resins include: Nippon Shokubai's "PX3-RP-37" and "RP-RX-61" (modified polystyrene resins containing oxazoline groups); Kuraray's "HYBRAR 5125" (SIS resin); Asahi Kasei's "S1611" (SEBS resin); Asahi Kasei's "H1041," "Tuftec H1043," "Tuftec P2000," and "Tuftec MP10" (hydrogenated styrene-based thermoplastic resins); Daicel's "Epofriend AT501" and "CT310" (epoxy-styrene-butadiene thermoplastic resins); Kuraray's "SEPTON HG252" (hydroxyl-modified polystyrene resin); Asahi Kasei's "Tuftec N503M" (carboxyl-modified polystyrene resin); and Asahi Kasei's "Tuftec..." N501 (modified polystyrene resin with amino groups); Asahi Kasei Corporation's "Tuftec M1913" (modified polystyrene resin with anhydride groups); Kuraray Corporation's "SEPTON S8104" (unmodified polystyrene resin); Kraton Corporation's "FG1924" (styrene-ethylene / butene-styrene block copolymer); "EF-40" (CRAY VALLEY Corporation), etc.

[0143] Examples of polyolefin resins include: low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, and other ethylene-based copolymers; polyolefin polymers such as polypropylene and ethylene-propylene block copolymers.

[0144] Examples of polybutadiene resins include: resins containing a hydrogenated polybutadiene backbone, polybutadiene resins containing hydroxyl groups, polybutadiene resins containing phenolic hydroxyl groups, polybutadiene resins containing carboxyl groups, polybutadiene resins containing acid anhydride groups, polybutadiene resins containing epoxy groups, polybutadiene resins containing isocyanate groups, polybutadiene resins containing urethane groups, and polyphenylene ether-polybutadiene resins.

[0145] Specific examples of polyamide-imide resins include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Other specific examples of polyamide-imide resins include modified polyamide-imides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane backbone) manufactured by Hitachi Chemical Co., Ltd.

[0146] Specific examples of polyethersulfone resins include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0147] Specific examples of polysulfone resins include polysulfones such as "P1700" and "P3500" manufactured by Solvay Performance Polymers.

[0148] Specific examples of polyetherimide resins include "Ultem" manufactured by GE.

[0149] Examples of polycarbonate resins include: hydroxyl-containing carbonate resins, phenolic hydroxyl-containing carbonate resins, carboxyl-containing carbonate resins, anhydride-containing carbonate resins, isocyanate-containing carbonate resins, and urethane-containing carbonate resins. Specific examples of polycarbonate resins include: "FPC0220" manufactured by Mitsubishi Gas Chemical Co., Ltd., "T6002" and "T6001" (polycarbonate diol) manufactured by Asahi Kasei Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd.

[0150] Specific examples of polyetheretherketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0151] Examples of polyester resins include: polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polypropylene terephthalate resin, polypropylene naphthalate resin, and polycyclohexanedimethyl terephthalate resin.

[0152] From the viewpoint of achieving significant effects of the present invention, the weight-average molecular weight (Mw) of the thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, particularly preferably 20,000 or more, preferably 70,000 or less, more preferably 60,000 or less, and particularly preferably 50,000 or less.

[0153] Since (D) the thermoplastic resin is an arbitrary component, it may not be present in the resin composition of the present invention. However, when it is present, if the non-volatile component in the resin composition is set to 100% by mass, its content is preferably 0.8% by mass or more, more preferably 0.9% by mass or more, and even more preferably 1.0% by mass or more. The upper limit is preferably 2.1% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.9% by mass or less. When the content of (D) the thermoplastic resin is within the above range, the stability and film flexibility of the varnish can be improved particularly effectively, and the cured resin composition can generally be made to have particularly good dielectric loss tangent and glass transition temperature.

[0154] <(E) Inorganic Filler Materials> The resin composition involved in this embodiment includes an inorganic filler as component (E). (E) The inorganic filler is a particle of an inorganic material. (E) The inorganic filler is contained in the resin composition in a particle state, and is usually contained in the cured product in a form that maintains the particle state.

[0155] Hollow inorganic filler materials with internal pores typically have a porosity greater than 0% by volume due to the presence of pores. (E) When inorganic filler materials include hollow inorganic filler materials, the relative permittivity of the cured material can be reduced. The porosity range of the hollow inorganic filler material is preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 20% by volume or more, preferably 95% by volume or less, more preferably 90% by volume or less, and further preferably 85% by volume or less. The porosity P (volume%) of the particles is defined as the volume ratio of the total volume of one or more pores present inside the particle to the overall volume of the particle relative to the outer surface of the particle (total volume of pores / volume of particle). This porosity P can be measured using the actual density (apparent density) D of the particles. M (g / cm 3 The theoretical value (true density) of the material density of the particles and the density of the particles. T (g / cm 3 ), which is calculated using the following formula (M1).

[0156] [Mathematical Expression 1]

[0157] The content of hollow inorganic filler material can be 0% or more, or greater than 0% of the total amount of inorganic filler material (E) (100% by mass), preferably 1% or more by mass, more preferably 2% or more by mass, even more preferably 3% or more by mass, preferably 80% or less by mass, more preferably 60% or less by mass, and even more preferably 40% or less by mass, relative to the total amount of inorganic filler material (E) (100% by mass).

[0158] Commercially available products as (E) inorganic filler materials include, for example: "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical Materials Co., Ltd.; "YC100C", "YA050C", "YA050C-MJE", "YA010C", "SC2500SQ", "SO-C4", "SO-C2", and "SO-C1" manufactured by Yatoma Co., Ltd.; "UFP-30", "DAW-03", and "FB-105FD" manufactured by Denka Co., Ltd.; "Silfil NSS-3N", "Silfil NSS-4N", and "Silfil NSS-5N" manufactured by Tokuyama Co., Ltd.; "CellSpheres" and "MGH-005" manufactured by Pacific Cement Co., Ltd.; and "LHP-208" manufactured by Ube EXSYMO Co., Ltd.

[0159] (E) The average particle size of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less or 1 μm or less, and particularly preferably 0.7 μm or less.

[0160] (E) The average particle size of inorganic filler materials can be measured using laser diffraction / scattering methods based on the Mie scattering theory. Specifically, a laser diffraction-scattering particle size distribution measuring device can be used to prepare the particle size distribution of the inorganic filler material on a volume basis, and the median particle size can be used as the average particle size for measurement. The sample for measurement can be obtained by weighing 100 mg of inorganic filler material and 10 g of methyl ethyl ketone into a vial and dispersing it ultrasonically for 10 minutes. For the sample for measurement, a laser diffraction-scattering particle size distribution measuring device can be used, with the light source wavelength set to blue and red, to measure the volume-based particle size distribution of the inorganic filler material in a flow cell manner, and the average particle size can be calculated from the obtained particle size distribution as the median particle size. Examples of laser diffraction-scattering particle size distribution measuring devices include the "LA-960" manufactured by Horiba Manufacturing Co., Ltd.

[0161] (E) The specific surface area of ​​the inorganic filler material is preferably 0.1 m². 2 / g or more, preferably 0.5m 2 / g or more, further preferably 1m 2 / g or more, especially preferably 3m 2 / g or more. Preferably 100m 2 / g or less, preferably 70m 2 / g or less, more preferably 50m 2 / g or less, especially preferably 40m 2 / g or less. (E) The specific surface area of ​​inorganic fillers can be determined as follows: According to the BET method, nitrogen gas is adsorbed on the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech), and the specific surface area is calculated using the BET multi-point method.

[0162] From the viewpoint of improving moisture resistance and dispersibility, (E) inorganic filler materials are preferably treated with surface treatment agents. Examples of surface treatment agents include: fluorinated silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. A single surface treatment agent can be used, or two or more can be used in combination.

[0163] Commercially available surface treatment agents include, for example: KBM403 (3-epoxypropoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM803 (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBE903 (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM573 (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., SZ-31 (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM103 (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-4803 (long-chain epoxy silane coupling agent) manufactured by Shin-Etsu Chemical Industry Co., Ltd., and KBM-7103 (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Industry Co., Ltd.

[0164] From the viewpoint of improving the dispersibility of inorganic filler materials, the degree of surface treatment using surface treatment agents is preferably within a specific range. Specifically, 100% by mass of the inorganic filler material is preferably surface treated with 0.2% to 5% by mass of a surface treatment agent, more preferably with 0.2% to 3% by mass of a surface treatment agent, and even more preferably with 0.3% to 2% by mass of a surface treatment agent.

[0165] The degree of surface treatment using surface treatment agents can be evaluated by the carbon content per unit surface area of ​​the inorganic filler material. From the viewpoint of improving the dispersibility of the inorganic filler material, the carbon content per unit surface area of ​​the inorganic filler material is preferably 0.02 mg / m². 2 The above, more preferably 0.1 mg / m 2 The above is further preferred to be 0.2 mg / m³. 2 That's all. On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition layer, 1.0 mg / m³ is preferred. 2 The following is more preferably 0.8 mg / m³2 The following is a further preferred value: 0.5 mg / m³ 2 the following.

[0166] (E) The carbon content per unit surface area of ​​the inorganic filler material can be determined after cleaning the surface-treated inorganic filler material with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK is added as a solvent to the surface-treated inorganic filler material, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid components, the carbon content per unit surface area of ​​the inorganic filler material can be determined using a carbon analyzer. A carbon analyzer such as the "EMIA-320V" manufactured by Horiba Manufacturing Co., Ltd. can be used.

[0167] The content of inorganic filler material (E) is 60% by mass or more, preferably 63% by mass or more, more preferably 65% ​​by mass or more, more preferably 90% by mass or less, more preferably 85% by mass or less, and more preferably 80% by mass or less, relative to 100% by mass of the non-volatile components of the resin composition. When the content of inorganic filler material (E) is within the above range, it can particularly effectively improve the stability and film flexibility of the resin varnish, and thus generally can make the dielectric loss tangent and glass transition temperature of the cured resin composition particularly good.

[0168] <(F) Curing Accelerator> The resin composition involved in this embodiment may include (F) curing accelerators as an optional component. Examples of (F) curing accelerators include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. Preferably, the (F) curing accelerator includes a curing accelerator selected from imidazole-based and amine-based curing accelerators. In addition, a free radical generator may also be used as the (F) curing accelerator. One (F) curing accelerator may be used alone, or two or more may be used in combination.

[0169] Examples of phosphorus-based curing accelerators include: tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitic phthalate, tetrabutylphosphonium hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butylmethylphosphonium tetraphenylborate, and other aliphatic phosphonium salts; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, and p-toluene. Aromatic phosphonium salts including triphenylphosphonium tetratolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetratolylborate, triphenylethylphosphonium tetraphenylborate, tri(3-methylphenyl)ethylphosphonium tetraphenylborate, tri(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc.; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-benzoquinone addition reactants such as triphenylphosphine-p-benzoquinone addition reactants; tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butylphosphine, etc. Aliphatic phosphines such as 2-butenylphosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; and tributylphenylphosphine, di-tert-butylphenylphosphine, methyl diphenylphosphine, ethyl diphenylphosphine, butyl diphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri(4-ethylphenyl)phosphine, tri(4-propylphenyl)phosphine, tri(4-isopropylphenyl)phosphine, tri(4-butylphenyl)phosphine, tri(4-tert-butylphenyl)phosphine, tri(2,4-dimethylphenyl)phosphine, tri(2,5-dimethylphenyl)phosphine, tri(2,6-dimethylphenyl)phosphine, etc. Aromatic phosphines include methylphenylphosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether.

[0170] Examples of urea-based curing accelerators include: 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. Aromatic dimethylureas include 1-dimethylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea)[toluenebisdimethylurea], etc.

[0171] Examples of guanidine-based curing accelerators include: dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanidine, 1-ethylbiguanidine, 1-n-butylbiguanidine, 1-n-octadecylbiguanidine, 1,1-dimethylbiguanidine, 1,1-diethylbiguanidine, 1-cyclohexylbiguanidine, 1-allylbiguanidine, 1-phenylbiguanidine, 1-(o-tolyl)biguanidine, etc.

[0172] Examples of imidazole-based curing accelerators include: 2-methylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, and 2,4-diamino-6-[2'-methylimidazolyl-(1')] -Ethyl-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-triazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline and other imidazole compounds, as well as adducts of imidazole compounds with epoxy resins, etc. Commercially available imidazole-based curing accelerators include, for example: "1B2PZ", "2E4MZ", "2MZA-PW", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2PHZ", "2PHZ-PW", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", and "C11Z-A" manufactured by Shikoku Chemical Co., Ltd.; and "P200-H50" manufactured by Mitsubishi Chemical Co., Ltd.

[0173] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt(II) and cobalt(III) acetylacetone, organocopper complexes such as copper(II) acetylacetone, organozinc complexes such as zinc(II) acetylacetone, organoiron complexes such as iron(III) acetylacetone, organonickel complexes such as nickel(II) acetylacetone, and organomanganese complexes such as manganese(II) acetylacetone. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0174] Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available amine-based curing accelerators can be used, such as "MY-25" manufactured by Ajinomoto Fine Technology Co., Ltd., and "DMAP" manufactured by Tokyo Chemical Industry Co., Ltd.

[0175] Examples of free radical generators include peroxide-based free radical polymerization initiators and azo-based free radical polymerization initiators.

[0176] Examples of peroxide-based free radical polymerization initiators include: hydrogen peroxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxide compounds such as tert-butyl cumene peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, di-tert-pentyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl percarbonate, and bis(4-tert-butylcyclohexyl)peroxide. Peroxydiacyl compounds such as hexyl peroxydicarbonate; peroxyester compounds such as tert-butyl peracetate, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanate, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxylaurate, 1,1-dimethylpropyl 2-ethylperoxyhexanoate, tert-butyl 2-ethylperoxyhexanoate, tert-butyl 3,5,5-trimethylperoxyhexanoate, tert-butyl peroxy-2-ethylhexyl monocarbonate, and tert-butyl peroxymaleate; etc.

[0177] Examples of azo nitrile compounds that serve as initiators for azo radical polymerization include: 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), 2,2'-azobis(2,4-dimethylpentanonitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carboxynitrile), 1-[(1-cyano-1-methylethyl)azo]formamide, 2-phenylazo-4-methoxy-2,4-dimethylpentanonitrile, etc.; 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], 2,2'-azobis[2-methyl-N-[1,1-bis( Azoamide compounds such as [hydroxymethyl]ethyl]propionamide, 2,2'-azobis[2-methyl-N-[2-(1-hydroxybutyl)]-propionamide], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(2-methylpropionamide) dihydrate, 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); alkylazo compounds such as 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane); etc.

[0178] Commercially available free radical initiators include, for example, those manufactured by Nippon Oil Company: "PERBUTYL C", "PERBUTYL A", "PERBUTYL P", "PERBUTYL L", "PERBUTYL O", "PERBUTYL ND", "PERBUTYL Z", "PERBUTYL I", "PERCUMYL P", "PERCUMYL D", "PERHEXYL D", "PERHEXYL A", "PERHEXYL L", "PERHEXYL Z", "PERHEXYL ND", "PERHEXYL O", and "PERHEXYL PV"; and "Luperox DTA" manufactured by Arkema.

[0179] When the non-volatile component in the resin composition is set to 100% by mass, the content of (F) curing accelerator is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more. The upper limit is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.

[0180] [(G) Any additives] The resin composition according to this embodiment may further include any additive as an optional component (G). The optional additive as component (G) does not contain substances belonging to components (A) to (F) above. Examples of optional additives as (G) include: organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentonite and montmorillonite; defoamers such as silicone-based defoamers, acrylic defoamers, fluorinated defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; and adhesion improvers such as ureasilanes. Binding agents such as triazole-based binding agents, tetraazole-based binding agents, and triazine-based binding agents; antioxidants such as hindered phenolic antioxidants; fluorescent whitening agents such as zirconia derivatives; surfactants such as fluorinated surfactants and organosilicon surfactants; dispersants such as phosphate ester-based dispersants, polyoxyethylene-based dispersants, acetylene-based dispersants, organosilicon dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate ester stabilizers, titanate stabilizers, aluminate stabilizers, zirconate stabilizers, isocyanate stabilizers, carboxylic acid stabilizers, and carboxylic anhydride stabilizers. (G) Any additive may be used alone or in combination of two or more.

[0181] It should be noted that the resin composition involved in this embodiment may or may not contain cyclic phosphazene compounds other than component (A). Furthermore, the resin composition involved in this embodiment may or may not contain phosphates. Moreover, the resin composition involved in this embodiment may or may not contain phosphorus-based flame retardants such as cyclic phosphazene compounds other than component (A) or phosphates. It should be noted that when the resin component in the resin composition is set to 100% by mass, the content of phosphorus-based flame retardants other than component (A) in the resin composition involved in this embodiment may be less than 5% by mass, may be 4% by mass or less, may be 3% by mass or less, may be 2% by mass or less, may be 1% by mass or less, may be 0.1% by mass or less, or may be set to 0% by mass. It should be noted that "phosphorus-based flame retardant" refers to a flame retardant containing phosphorus atoms. Furthermore, the resin composition involved in this embodiment may or may not contain fluoropolymers. Additionally, the resin composition involved in this embodiment may or may not contain poly(aryl ether) polymers containing the following monomer units: pyrimidine, pyrazine, or pyridazine. That is, compositions containing poly(arylene ether) polymers comprising monomer units comprising pyrimidine, pyrazine, or pyridazine groups can be excluded from the resin compositions involved in this embodiment.

[0182] [(H) solvent] The resin composition according to this embodiment may be combined with non-volatile components such as components (A) to (G) to further include solvent (H) as a volatile component. Organic solvents are typically used as solvent (H). Examples of organic solvents include: ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; and 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and carbitol acetate. Ether ester solvents such as acetate, γ-butyrolactone, and methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene.

[0183] Solvent (H) can be used alone or in combination of two or more. Preferably, solvent (H) includes a ketone solvent. Using a ketone solvent can particularly effectively improve the stability and film flexibility of the varnish. The content of the ketone solvent relative to 100% by mass of the total amount of solvent (H) is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more, preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less. In particular, when the resin composition is a resin varnish, the content of the ketone solvent contained in the resin varnish is preferably within the above-mentioned range.

[0184] The solvent (H) preferably includes a high-boiling-point solvent having a boiling point of 100°C or higher. Examples of preferred high-boiling-point solvents include: cyclohexanone (boiling point 155°C), ethylcyclohexane (boiling point: 130–132°C), tetrahydronaphthalene (boiling point: 206–208°C), decahydronaphthalene (boiling point: 185–195°C), methylpentyl ketone (2-heptanone, boiling point: 151°C), 2-methoxypropanol (boiling point: 102°C), and toluene (boiling point: 111°C). Using a high-boiling-point solvent can particularly effectively improve the stability and film flexibility of the varnish. The content of the high-boiling-point solvent is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, relative to 100% by mass of the total amount of solvent (H). In particular, when the resin composition is a resin varnish, the content of high-boiling-point solvent contained in the resin varnish is preferably within the above-mentioned range.

[0185] The solvent (H) preferably includes a non-aromatic high-boiling-point solvent. A non-aromatic high-boiling-point solvent refers to a high-boiling-point solvent that does not contain an aromatic ring in its molecule. Examples of non-aromatic high-boiling-point solvents include cyclohexanone, ethylcyclohexane, decahydronaphthalene, methylpentyl ketone, and 2-methoxypropanol. From the viewpoint of membrane flexibility, the content of non-aromatic high-boiling-point solvents such as cyclohexanone is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, relative to 100% by mass of the total amount of solvent (H). From the viewpoint of varnish stability and adhesion between the resin composition layer and the protective film, it is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, 30% by mass or less, or 20% by mass or less. Furthermore, from the viewpoint of film flexibility, the content of non-aromatic high-boiling-point solvents is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more, relative to 100% by mass of the total resin composition. From the viewpoint of varnish stability and adhesion between the resin composition layer and the protective film, it is preferably 12% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, 6% by mass or less, or 5% by mass or less. In particular, when the resin composition is a resin varnish, the content of high-boiling-point solvents contained in the resin varnish is preferably within the above-mentioned range.

[0186] In particular, the mass ratio of non-aromatic high-boiling-point solvents such as cyclohexanone to (A) cyclic phosphazene compound (non-aromatic high-boiling-point solvent / (A) cyclic phosphazene compound) is preferably 1.0 or more, more preferably 2.0 or more, further preferably 3.0 or more, more preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. When the mass ratio (non-aromatic high-boiling-point solvent / (A) cyclic phosphazene compound) is within the above range, the stability of the varnish, the film flexibility, and the adhesion between the resin composition layer and the protective film can be improved particularly effectively.

[0187] In one embodiment, when the (H) solvent contains toluene, from the viewpoint of resin compatibility and varnish stability, the toluene content is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and further preferably 70% by mass or less, relative to 100% by mass of the total resin composition. Furthermore, the toluene content is preferably 3% by mass or more, more preferably 5% by mass or more, further preferably 8% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less, relative to 100% by mass of the total resin composition. Moreover, the mass ratio of toluene to the (A) cyclic phosphazene compound (toluene / (A) cyclic phosphazene compound) is preferably 5 or more, more preferably 8 or more, further preferably 9 or more, preferably 25 or less, more preferably 20 or less, and further preferably 15 or less.

[0188] In the case of a resin varnish according to this embodiment, the content of (H) solvent relative to 100% by mass of the total amount of the resin varnish is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% by mass or less or 20% by mass or less. Resin varnishes containing (H) solvent within such a range exhibit particularly excellent varnish stability and film flexibility.

[0189] On the other hand, in the state where a resin composition layer is formed, the content of (H) solvent contained in the resin composition layer is generally less than the content of (H) solvent in the resin varnish. Specifically, the range of (H) solvent content of the resin composition contained in the resin composition layer relative to 100% by mass can be, for example, less than 50% by mass, less than 40% by mass, less than 30% by mass, less than 20% by mass, less than 15% by mass, or less than 10% by mass. The lower limit can be 0% by mass, but is generally greater than 0% by mass.

[0190] [Method for manufacturing the resin composition] The resin composition described in this embodiment can be manufactured, for example, by mixing components that may be included in the resin composition. These components can be mixed in part or all at once, or sequentially. During the mixing of the components, the temperature can be appropriately set, allowing for temporary or continuous heating and / or cooling. Furthermore, stirring or agitation can be performed during the mixing of the components.

[0191] [Properties of the resin composition and its cured product] The resin composition described in this embodiment exhibits excellent varnish stability. Therefore, when the resin composition is a resin varnish, the precipitation of components from the resin varnish due to storage can be suppressed. In one example, when the resin composition was stored under refrigeration for 3 days, the increase rate of precipitates due to this storage was less than 1.5%. The increase rate of precipitates can be determined using the method described in Test Example 1 of the following embodiments.

[0192] The resin composition involved in this embodiment can exhibit excellent film flexibility. Therefore, based on this resin composition, a cured product of the resin composition with excellent mechanical properties, specifically excellent tensile strength, can be formed. In one example, a tensile strength of the resin composition layer formed from the resin composition tends to exceed 45 MPa, preferably 50 MPa or more, and more preferably 55 MPa or more. The tensile strength of the cured resin composition can be determined by the method described in Test Example 4 of the embodiments described later.

[0193] By curing the resin composition according to this embodiment, a cured product of the resin composition can be obtained. Then, a cured layer can be formed using this cured product. Generally, since heat is applied during the curing of the resin composition, volatile components such as solvent (H) in the resin composition can evaporate due to the heat during curing. Therefore, the cured product obtained by curing the resin composition can contain non-volatile components such as components (A) to (G) or their reaction products. The cured layer can be used, for example, as an insulating layer for a circuit board.

[0194] The cured resin composition involved in this embodiment typically exhibits excellent dielectric properties, specifically, a low dielectric loss tangent Df. In one example, the dielectric loss tangent Df of the cured product is preferably 0.008 or less, more preferably 0.006 or less, and even more preferably 0.005 or less. The lower limit of the dielectric loss tangent Df is not particularly limited, and for example, it can be 0.0010 or more.

[0195] The dielectric loss tangent Df of the cured material described above can be measured using the resonant cavity perturbation method under the conditions of a measurement frequency of 5.8 GHz and a measurement temperature of 23 °C. If the sample is a resin composition before curing, the resin composition can be cured at 190 °C for 90 minutes to obtain a cured material, and the dielectric loss tangent Df of the cured material can be measured. The specific measurement method can be the method described in Test Example 3 of the following embodiments.

[0196] The cured resin composition involved in this embodiment typically exhibits excellent heat resistance, specifically, a high glass transition temperature (Tg). In one example, the glass transition temperature (Tg) of the cured product is preferably 150°C or higher. Upper limits may be, for example, 300°C or lower, 250°C or lower, 200°C or lower, etc.

[0197] The glass transition temperature of the cured product described above can be determined by thermomechanical analysis using the tensile load method under the conditions of a load of 1g and a heating rate of 5°C / min. If the sample is a resin composition before curing, the resin composition can be cured at 190°C for 90 minutes to obtain a cured product, and the glass transition temperature Tg of the cured product can be measured. The specific measurement method can be the method described in Test Example 3 of the following examples.

[0198] The resin composition and cured product involved in this embodiment are not particularly limited, but are generally not fibrous. That is, resin compositions and cured products having a fibrous shape can be excluded from the resin compositions and cured products involved in this embodiment.

[0199] <Uses of Resin Compositions> The resin composition described in this embodiment can be used for forming insulating layers, and is particularly preferred for forming insulating layers on circuit boards. Additionally, the resin composition can be used for manufacturing resin sheets. Typically, these resin sheets are used to form insulating layers. Furthermore, the resin composition can also be used for other applications, such as solder resist, underfill material, chip bonding material, via-filling resin, sealing resin, and component embedding resin. It should be noted that the resin composition described in this embodiment is not particularly limited, but it is generally not used for fiber formation. That is, the application of fibers can be excluded from the uses of the resin composition described in this embodiment.

[0200] <Resin Sheets> One embodiment of the present invention relates to a resin sheet comprising a support and a resin composition layer formed on the support. The resin composition layer comprises the resin composition described above, preferably comprising only the resin composition described above.

[0201] From the viewpoint of thinness, the thickness of the resin composition layer in the resin sheet is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 1 μm or more, 3 μm or more, 5 μm or more, etc.

[0202] Examples of supports include: films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being more preferred.

[0203] When a film made of plastic material is used as a support, examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"); acrylics such as polycarbonate (hereinafter sometimes abbreviated as "PC") and polymethyl methacrylate (PMMA); cyclic polyolefins; triacetyl cellulose (TAC); polyether sulfide (PES); polyether ketone; and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0204] When metal foil is used as a support, examples of metal foil include copper foil and aluminum foil. Copper foil is preferred. As copper foil, foil containing a single metal such as copper can be used, or foil containing an alloy of copper and other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0205] For the support, surface treatments such as matte finish, corona treatment, and antistatic treatment can be applied to the surface that bonds with the resin composition layer.

[0206] As a support, a support with a release layer can be used on the surface that bonds to the resin composition layer. Examples of release agents used in the release layer of the support with a release layer include, for example, one or more release agents selected from alkyd-based, polyolefin-based, polyurethane-based, and silicone-based release agents. Commercially available products can be used as the support with the release layer, such as, for example, PET films having a release layer primarily composed of silicone-based or alkyd-based release agents, such as Lintec's "PET501010", "SK-1", "AL-5", and "AL-7"; Toray's "Lumirror T60"; Teijin's "Purex"; and Unitika's "Unipeel".

[0207] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 75 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. When using a support with a release layer, the overall thickness of the support with the release layer is preferably within the above range.

[0208] Depending on the requirements, the resin sheet can also have any components. For example, the resin sheet can have a protective film that protects the resin composition layer. The protective film is usually applied to the side of the resin composition layer that is not bonded to the support (i.e., the side opposite to the support). The thickness of the protective film is not particularly limited, and can be, for example, from 1 μm to 40 μm. The presence of a protective film can suppress the adhesion of debris and the generation of damage on the surface of the resin composition layer.

[0209] Resin sheets can be manufactured, for example, by forming a resin composition layer on a support. Specifically, a resin sheet can be manufactured by applying a resin varnish, which is a resin composition, to a support and then allowing it to dry to form a resin composition layer.

[0210] The resin composition can be coated using a coating apparatus such as a die coater. Drying can be performed by methods such as heating or hot air blowing. Drying conditions are not particularly limited, but drying is typically carried out with a solvent content in the resin composition layer of 10% by mass or less, preferably 5% by mass or less. Depending on the boiling point of the solvent, for example, when using a resin composition containing 30% to 60% by mass of solvent, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0211] The manufactured resin sheets can be wound into rolls for storage. When the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[0212] <Circuit substrate> One embodiment of the present invention relates to a circuit board comprising a cured form of the aforementioned resin composition. Typically, a circuit board includes a cured layer comprising a cured form of the resin composition. The cured layer may comprise only a cured form of the resin composition. The cured layer may be used, for example, as an insulating layer such as an interlayer insulating layer. The thickness of the cured layer is not particularly limited, and may, for example, be within the same range as the thickness of the resin composition layer on the resin sheet. Furthermore, the cured layer may generally have the same properties as the cured form of the aforementioned resin composition.

[0213] Preferably, the circuit board includes an inner substrate on which the aforementioned cured layer serves as an insulating layer. Additionally, the circuit board may include a conductor layer. For example, a conductor layer may be provided on the insulating layer. Hereinafter, examples of preferred methods for manufacturing the circuit board will be described.

[0214] The preferred example involves a method for manufacturing a circuit board that includes: The process of forming a resin composition layer on the inner substrate (I), and Step (II) for curing the resin composition layer.

[0215] An "inner layer substrate" is a component that forms the substrate of a circuit board, and examples include glass epoxy boards, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. Furthermore, the inner layer substrate may have conductive layers on one or both sides. Additionally, the conductive layers of the inner layer substrate may be patterned. Circuit wiring can be formed using the patterned conductive layers. An inner layer substrate with conductive layers formed on one or both sides of the substrate is sometimes called an "inner layer circuit board." Furthermore, intermediate components to be further formed with insulating layers and / or conductive layers during the manufacture of a circuit board are also included in the term "inner layer substrate." Additionally, inner layer substrates with built-in components can be used.

[0216] From the viewpoint of utilizing the advantage of suppressing the formation of large particles caused by the leaching of components in the resin varnish, it is preferable that the circuit board using the resin composition according to the above embodiments has a small minimum line width and line spacing (L / S) of the circuit wiring. Unless otherwise specified, "line width" (L) refers to the width of the circuit wiring, and "line spacing" (S) refers to the spacing between the wirings. The range of the minimum line width and line spacing (L / S) is preferably 10 μm / 10 μm or less, more preferably 5 μm / 5 μm or less, further preferably 3 μm / 3 μm or less, preferably 0.1 μm / 0.1 μm or more, more preferably 0.5 μm / 0.5 μm or more, and further preferably 1 μm / 1 μm or more. In addition, the wiring pitch is preferably 20 μm or less, more preferably 10 μm or less, further preferably 6 μm or less, preferably 0.2 μm or more, more preferably 1 μm or more, and further preferably 2 μm or more. Line width and line spacing (L / S) and wiring spacing can be uniform or non-uniform throughout the conductor layer.

[0217] The formation of a resin composition layer on the inner substrate can be carried out, for example, by a method that includes a resin composition such as a resin varnish coated on the inner substrate and then dried as needed, but it is preferable to use a resin sheet. The method for forming a resin composition layer using a resin sheet typically includes a step of laminating the resin sheet to the inner substrate. The lamination of the resin sheet to the inner substrate is performed in such a way that the resin composition layer of the resin sheet is bonded to the inner substrate. This lamination can also be performed, for example, by heating and pressing the resin sheet onto the inner substrate from the support side. Examples of components for heating and pressing the resin sheet onto the inner substrate (hereinafter also referred to as "heat-pressing component") include, for example, a heated metal plate (SUS end plate, etc.) or a metal roller (SUS roller, etc.). It should be noted that it is preferable not to directly press the heat-pressing component onto the resin sheet, but rather to press it using an elastic material such as heat-resistant rubber so that the resin sheet fully follows the surface irregularities of the inner substrate.

[0218] The lamination of the inner substrate and the resin sheet can be performed by vacuum lamination. In vacuum lamination, the heating and pressing temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C; the heating and pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa; and the heating and pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. Lamination is preferably performed under reduced pressure conditions of 26.7 hPa or less.

[0219] Lamination can be performed using commercially available vacuum laminators. Examples of commercially available vacuum laminators include the vacuum pressure laminator manufactured by Meiki Seisakusho, the vacuum dressing machine manufactured by Nikko-materials, and batch vacuum pressure laminators.

[0220] A method for manufacturing a circuit board may include: after lamination, pressing a heated bonding member under normal pressure (atmospheric pressure), for example from the support side, thereby performing a smoothing treatment on the resin sheet. The pressing conditions for the smoothing treatment can be the same as the conditions for the heated bonding of the lamination described above. The smoothing treatment can be performed using a commercially available laminator. Lamination and smoothing treatment can also be performed continuously using the aforementioned commercially available vacuum laminator.

[0221] The circuit board manufacturing method described in this example includes a step (II) after step (I) in which the resin composition layer is cured. By curing the resin composition layer in step (II), an insulating layer can be formed as a cured product containing the resin composition.

[0222] The curing of the resin composition layer is usually carried out by heat curing. The heat curing conditions of the resin composition layer can also vary depending on the type of resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. In addition, the curing time is preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0223] A method for manufacturing a circuit board may include preheating the resin composition layer at a temperature lower than the curing temperature before thermal curing. For example, before thermal curing the resin composition layer, it can typically be preheated at a temperature of 50°C to 150°C, preferably 60°C to 140°C, more preferably 70°C to 130°C, for at least 5 minutes, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes. Preheating is usually performed after step (I). Furthermore, if a smoothing treatment is performed after laminating the inner layer substrate and the resin sheet, preheating can typically be performed after the smoothing treatment.

[0224] When using resin sheets, the circuit board manufacturing method may include a step of peeling off the support of the resin sheet after the inner layer substrate and the resin sheet are laminated. The peeling off of the support may be performed between steps (I) and (II), or after step (II). Furthermore, if the circuit board manufacturing method, as described below, includes a step (III) of forming holes in the insulating layer, a step (IV) of roughening the insulating layer, and a step (V) of forming a conductor layer, the peeling off of the support may be performed between steps (II) and (III), between steps (III) and (IV), or between steps (IV) and (V).

[0225] The manufacturing method of the circuit board may include a step (III) after step (II) to form holes such as via holes and through holes in the insulating layer. The method for forming the holes can be selected based on factors such as the composition of the resin composition used in the formation of the insulating layer. For example, holes can be formed by processing methods such as drilling, laser processing, and plasma processing, with laser processing being preferred. For example, holes can be formed by irradiating the insulating layer with a laser after the support is peeled off, or holes can be formed by irradiating the insulating layer with a laser through the support. The size and shape of the holes can be appropriately determined according to the design of the circuit board.

[0226] The method for manufacturing a circuit board may include a step (IV) of roughening the insulating layer. This roughening process roughens the surface of the insulating layer. Furthermore, it removes contaminants (resin residue) from the insulating layer. Therefore, this roughening process is sometimes referred to as a "decontamination process." For example, if a hole is formed in step (III), contaminants may form within the hole; therefore, it is preferable to perform the roughening process (IV) after step (III) to remove the aforementioned contaminants.

[0227] There are no particular limitations on the steps and conditions of the roughening treatment; known steps and conditions commonly used in forming the insulating layer of a circuit board can be adopted. For example, the insulating layer can be roughened by sequentially performing a swelling treatment using a swelling solution, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing solution.

[0228] Examples of swelling solutions used in the roughening process include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Sodium hydroxide solution and potassium hydroxide solution are more preferred. Commercially available swelling solutions include, for example, "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Ammet Japan Co., Ltd. Swelling treatment using a swelling solution can be performed, for example, by immersing the insulating layer in a swelling solution at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin in the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling solution at 40°C to 80°C for 5 to 15 minutes.

[0229] Examples of oxidizing agents used in roughening processes include alkaline permanganate solutions, such as potassium permanganate or sodium permanganate dissolved in an aqueous solution of sodium hydroxide. Oxidation treatment using alkaline permanganate solutions or similar oxidizing agents preferably involves immersing the insulating layer in an oxidizing agent solution heated to 60°C to 100°C for 10 to 30 minutes. Furthermore, the concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidizing agents include, for example, alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securiganth P" manufactured by Ammet Japan Co., Ltd.

[0230] The neutralizing solution used in the roughening process is preferably an acidic aqueous solution. Commercially available examples include, for instance, "Reduction Solution Securiganth P" manufactured by Ammet Japan Co., Ltd. The neutralization process using the neutralizing solution can be performed by immersing the surface that has undergone oxidation treatment with an oxidizing agent in a neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From an operational point of view, it is preferable to immerse the object that has undergone oxidation treatment with an oxidizing agent in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0231] The method for manufacturing a circuit board may include a step (V) of forming a conductor layer on an insulating layer. In the case where the method for manufacturing a circuit board includes step (III) or (IV), the step (V) of forming the conductor layer is generally preferably performed after steps (III) and (IV).

[0232] The conductor material used in the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer comprises one or more metals selected from gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer can be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above-mentioned metals (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). From the viewpoints of versatility in conductor layer formation, cost, and ease of pattern formation, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy, is preferred. More preferably, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or an alloy layer of nickel-chromium alloy, is preferred. A single metal layer of copper is even more preferred.

[0233] The conductor layer can have a single-layer structure or a multi-layer structure comprising two or more single-metal layers or alloy layers of different types of metals or alloys. In the case of a multi-layer conductor layer, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of nickel-chromium alloy.

[0234] The thickness of the conductor layer varies depending on the design of the circuit board, but is preferably 3μm to 35μm, and more preferably 5μm to 30μm.

[0235] The conductor layer can be formed by plating. For example, a conductor layer with a desired wiring pattern can be formed by plating the surface of the insulating layer using conventionally known techniques such as semi-additive and fully additive methods. From the viewpoint of ease of manufacturing, the semi-additive method is preferred. An example of forming a conductor layer using the semi-additive method is shown below.

[0236] First, an electroless plating layer (plating seed layer) is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed electroless plating layer, exposing a portion of the electroless plating layer, corresponding to the desired wiring pattern. After forming an electrolytic plating layer on the exposed electroless plating layer by electrolytic plating, the mask pattern is removed. Then, the unwanted electroless plating layer is removed by etching, thus forming a conductor layer with the desired wiring pattern.

[0237] As another example, the conductor layer can be formed using metal foil. When forming the conductor layer using metal foil, it is preferable to perform step (V) between step (I) and step (II). For example, after step (I), the support is removed, and metal foil is laminated onto the surface of the exposed resin composition layer. The lamination of the resin composition layer and the metal foil can be performed using a vacuum lamination method. The lamination conditions can be the same as those described for step (I). Next, step (II) is performed to form an insulating layer. Then, using the metal foil on the insulating layer, a conductor layer with a desired wiring pattern can be formed using known techniques such as subtractive processing or modified semi-additive processing. Metal foil can be manufactured, for example, by known methods such as electrolysis or rolling. Commercially available metal foils include, for example, HLP foil and JXUT-III foil manufactured by JX Metals Corporation, and 3EC-III foil and TP-III foil manufactured by Mitsui Mining & Metals Corporation.

[0238] When a conductor layer is formed on an insulating layer, the manufacturing method of the circuit board may include annealing after the conductor layer is formed. Annealing can improve the adhesion between the insulating layer and the conductor layer. Annealing can be performed, for example, by heating at 150°C to 210°C for 20 to 180 minutes.

[0239] In the manufacturing method of the circuit board, each of the above-mentioned processes may be performed only once or repeatedly more than twice. For example, processes (I) to (V) can be repeatedly performed to form a circuit board with a multilayer structure, such as a multilayer printed wiring board having multiple insulating layers and conductor layers.

[0240] The method for manufacturing a circuit board can be combined with the aforementioned steps to further include any additional steps. For example, the method may include a step of placing a semiconductor chip in a manner that bonds it to a conductive layer. Specifically, in the case of manufacturing a circuit board for a semiconductor chip package containing a semiconductor chip, the method may include a step of placing the semiconductor chip. The conditions for placing the semiconductor chip can be appropriate conditions that allow for conductive connection between the terminal electrodes of the semiconductor chip and the conductive layer formed on the insulating layer. For example, conditions used in flip-chip mounting can be used. Furthermore, the semiconductor chip can be bonded via an insulating adhesive or by reflow soldering. Furthermore, if necessary, the placed semiconductor chip can be filled with a molding underfill material. Additionally, the method may include, for example, a step of forming a sealing layer, a step of forming a solder resist layer, and a step of cutting the manufactured circuit board into monolithic wafers.

[0241] Examples of circuit boards include printed wiring boards and semiconductor chip packages. Examples of semiconductor chip packages include FC-CSP, MIS-BGA packages, ETS-BGA packages, fan-out type WLP (Wafer Level Package), fan-in type WLP, fan-out type PLP (Panel Level Package), and fan-in type PLP. In these semiconductor chip packages, it is preferable to use a cured product formed by curing the aforementioned resin composition to form the rewiring layer as an insulating layer. However, the circuit board is not limited to those examples here.

[0242] Semiconductor Devices The circuit board described above can be used in the manufacture of semiconductor devices. Semiconductor devices include the circuit board described above. Examples of semiconductor devices include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablets, wearable devices, digital cameras, medical devices, and televisions) and vehicles (e.g., motorcycles, automobiles, trams, ships, and airplanes). Example

[0243] The present invention will be specifically described below with reference to embodiments. However, the present invention is not limited to the embodiments described below. In the following description, the terms "parts" and "%" to indicate quantities refer to "parts by mass" and "% by mass," respectively, unless otherwise specified. The temperature condition is room temperature (23°C) unless otherwise specified, and the pressure condition is atmospheric pressure (1 atm) unless otherwise specified.

[0244] <Synthetic Example 1: Maleimide Compound A> A MEK solution (62% by mass) of a maleimide compound synthesized using the method described in Synthesis Example 1 of Japan Invention Association Publication No. 2020-500211 was prepared. This maleimide compound has the structure shown in the following formula.

[0245] [Chemical Formula 19]

[0246] <Synthetic Example 2: Maleimide Compound B> (I) Synthesis of intermediate amine compound (a-1) In a flask equipped with a thermometer, cooling tubes, a Dean-Stark trap, and a stirrer, 400 g (3.3 mol) of 2-ethylaniline, 127 g of compound (b) with a benzyl ether skeleton (NIKANOL L, manufactured by Fudow), 193 g of toluene, and 53 g of activated clay were added. The mixture was heated to 120 °C while stirring and held for 30 minutes. Then, the temperature was increased to 150 °C and held for 3 hours. After this holding period, the temperature was increased to 200 °C over 30 minutes and held for 10 hours. After this holding period, the mixture was diluted with 193 g of toluene, and the activated clay was separated by filtration. The solvent and excess 2-ethylaniline were removed from the filtrate by distillation under reduced pressure to obtain the intermediate amine compound (a-1) (amine equivalent 209 g / eq.).

[0247] (II) Maleimide In a 2L flask equipped with a thermometer, cooling tube, Dean-Stark separator, and stirrer, 73.2 g (126 mol, 1.3 equivalents) of maleic anhydride and 461 g of toluene were added and stirred at room temperature. Next, a mixed solution of 209 g (1 equivalent) of intermediate amine compound (a-1) and 57.7 g of N,N-dimethylformamide (DMF) was added dropwise over 1 hour, and the reaction was allowed to proceed for 2 hours. Then, 9.72 g of p-toluenesulfonic acid monohydrate was added to the reaction solution, and the solution was heated to 115°C. After cooling and separating the azeotropic water and toluene under reflux, only the toluene was returned to the system for a 5-hour dehydration reaction. After air cooling to room temperature, the resulting brown solution obtained by vacuum concentration was dissolved in 600 g of ethyl acetate, washed three times with 200 g of deionized water, and then washed three times with 150 g of 2% sodium bicarbonate aqueous solution. After adding sodium sulfate and drying, the reactants obtained by vacuum concentration were dried at 80°C for 4 hours to obtain maleimide compound B. In the manufacture of the resin compositions described later, it was used in the form of a toluene solution (62% non-volatile components).

[0248] [Chemical Formula 20]

[0249] <Synthesis Example 3: Synthesis of Vinyl Resin A> According to Example 1 of International Publication No. 2017 / 115813, 3.0 mol (390.6 g) of divinylbenzene, 1.8 mol (229.4 g) of ethylvinylbenzene, 10.2 mol (1066.3 g) of styrene, and 15.0 mol (1532.0 g) of n-propyl acetate were added to a 5.0 L reactor. 600 mmol of a boron trifluoride diethyl ether complex was added at 70 °C, and the reaction was carried out for 4 hours. After stopping the polymerization solution with an aqueous sodium bicarbonate solution, the oil layer was washed three times with pure water, and the polymer was recovered by vacuum devolatilization at 60 °C. The obtained polymer was weighed, confirming that 896.7 g of vinyl resin A was obtained. The Mw of vinyl resin A was 41300. In the manufacture of the resin compositions of the examples described later, a toluene solution (50% non-volatile components) was used.

[0250] <Examples 1-12, Comparative Examples 1-5> Weigh each component according to the mass fractions recorded in Table 2 below, mix them, and disperse them evenly using a high-speed rotary mixer to obtain a resin varnish as a resin composition.

[0251] <First Dissolution Test and Second Dissolution Test> To investigate the solubility of the (A) cyclic phosphazene compound used in the examples in cyclohexanone, the following first and second dissolution tests were conducted.

[0252] (First dissolution test) Add 0.5 g of (A) cyclic phosphazene compound to 10 g of cyclohexanone. While heating at 25°C, sonicate for 10 minutes to dissolve the (A) cyclic phosphazene compound. After the added (A) cyclic phosphazene compound is completely dissolved in cyclohexanone, add another 0.5 g of (A) cyclic phosphazene compound and repeat the sonication for 10 minutes. Repeat the above addition of (A) cyclic phosphazene compound and sonication until the (A) cyclic phosphazene compound no longer dissolves in cyclohexanone and precipitation is observed. The cumulative amount added until the (A) cyclic phosphazene compound no longer dissolves in cyclohexanone and precipitation is observed is taken as the dissolved amount of (A) cyclic phosphazene compound in cyclohexanone.

[0253] (Second Dissolution Test) Except that the measurement temperature was changed to 70°C, the amount of (A) cyclic phosphazene compound dissolved in 10g of cyclohexanone at 70°C was determined by the same method as the first dissolution test described above.

[0254] The details of each component recorded in Table 2 are as follows: (A) Cyclic phosphazene compounds FP-72TP: A cyclic phosphazene compound as shown in the following formula. It has a melting point higher than 280°C, a phosphorus content of 14.4%, a nitrogen content of 6.5%, an average particle size of 1 μm, and a maximum particle size of 10 μm. In the first dissolution test, its solubility in 10 g of cyclohexanone at 25°C was 0.00 g, and in the second dissolution test, its solubility in 10 g of cyclohexanone at 70°C was also 0.00 g.

[0255] [Chemical Formula 21]

[0256] FP-72TP pulverized product: The above-mentioned FP-72TP was processed using a bead mill to obtain the cyclic phosphazene compound of the above formula with an average particle size of 0.5 μm and a maximum particle size of 5.0 μm.

[0257] • HCA-HQ-HST: The compound shown in the following formula. Used as a flame retardant. Manufactured by Sankwang Corporation. Phosphorus content 10% by mass, average particle size 1.5 μm. After conducting the first and second dissolution tests, the solubility in 10 g of cyclohexanone at 25°C was 0.05 g, and the solubility in 10 g of cyclohexanone at 70°C in the second dissolution test was 0.40 g.

[0258] [Chemical Formula 22]

[0259] •FP-100: The compound shown in the following formula. Used as a flame retardant. Manufactured by Fushimi Pharmaceutical Co., Ltd. Phosphorus content 13.4% by mass. The solubility in 10g of cyclohexanone at 25°C, as determined in the first dissolution test, is 0.40g. The solubility in 10g of cyclohexanone at 70°C, as determined in the second dissolution test, is also 0.40g.

[0260] [Chemical Formula 23]

[0261] (B) Maleimide resin MIR-3000-70MT: Aromatic maleimide resin (manufactured by Nippon Kayaku Co., Ltd., a MEK / toluene mixed solution with 70% non-volatile components). MIR-5000-60T: Aromatic maleimide resin (manufactured by Nippon Kayaku Co., Ltd., a toluene mixture with 60% non-volatile components) • Maleimide compound A: The maleimide compound synthesized in Example 1 • Maleimide compound B: The maleimide compound synthesized in Example 2 •SLK-6895: Aliphatic maleimide resin (manufactured by Shin-Etsu Chemical Industry Co., Ltd., MEK solution with 90% non-volatile components) •SLK-1500: Aliphatic maleimide resin (manufactured by Shin-Etsu Chemical Industry Co., Ltd., MEK solution with 70% non-volatile components)

[0262] (C) Free radical polymers • OPE-2St: Vinyl benzyl modified polyphenylene ether (manufactured by Mitsubishi Gas Chemical Co., Ltd., toluene solution with 65% non-volatile components) • SA9000: Methacrylic acid modified polyphenylene ether (manufactured by SABIC Innovative Plastics Co., Ltd.) • Vinyl Resin A: The vinyl resin synthesized in Synthesis Example 3 • DAD: diallyl biphenyl ester (manufactured by Nisshoku Techno Fine Chemical Co., Ltd.)

[0263] (D) Thermoplastic resin • P2000: Styrene-based elastomer (manufactured by Asahi Kasei Corporation) PIAD200: Polyimide resin (manufactured by Arakawa Chemical Co., Ltd., a mixed solution of cyclohexanone, dimethyl glycol, and methylcyclohexane with 30% non-volatile components) YX7553BH30: Phenoxy resin (manufactured by Mitsubishi Chemical Corporation, a 1:1 solution of MEK and cyclohexanone with 30% non-volatile components).

[0264] (E) Inorganic filler materials • SO-C2: Spherical silica (manufactured by Arduma, average particle size 0.5 μm, specific surface area 5.8 m²) 2 / g), surface treated with a silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-573") for use. • LHP-208: Spherical hollow silica (manufactured by Ube EXSYMO, average particle size 0.5 μm, porosity 50% by volume), surface-treated with amine silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM573") for use. UFP-30: Spherical silica (manufactured by Denka, average particle size 0.3 μm, specific surface area 30 m²). 2 / g), and is used by surface treatment with a silane coupling agent (Shin-Etsu Chemical Industry Co., Ltd. "KBM-573").

[0265] (F) Curing accelerator • Luperox DTA: Di-tert-amyl peroxide (manufactured by Arkema) ·PERCUMYL D: Dicumyl peroxide (manufactured by Nippon Oil Company) ·1B2PZ: Imidazole-based curing accelerator (manufactured by Shikoku Chemical Industry Co., Ltd.)

[0266] (H) Solvent: ·(H-1)MEK: Methyl ethyl ketone (H-3)toluene: Toluene.

[0267] <Experimental Example 1: Evaluation of Varnish Stability> For the resin varnishes obtained in the examples and comparative examples, filtration was performed to remove secondary aggregates and foreign matter from the inorganic filler material. The filtration method involved conveying the resin varnish through a mesh filter using a metering pump. The filtration pressure (differential pressure) was set to 0.4 MPa or less to prevent clogging of the mesh filter. Furthermore, a pump with minimal pulsation was used to maintain a constant filtration pressure. The mesh size of the filter was 10 μm to 30 μm. The filtered resin varnish was observed using an optical microscope, and the number of precipitates with a particle size of 10 μm or larger was counted (initial). Next, the filtered resin varnish was stored at refrigeration (4°C) for 3 days. The stored resin varnish was observed using an optical microscope, and the number of precipitates with a particle size of 10 μm or larger was counted (refrigerated for 3 days). The increase rate of precipitates was calculated using the following formula (M2): Increase rate = Number of precipitates (refrigerated for 3 days) / Number of precipitates (initial) (M2) The stability of the varnish is determined according to the following criteria: "×": The increase rate of precipitates is 1.5% or higher. "〇": The increase rate of precipitates is greater than 1.2 and less than 1.5. "◎": The increase rate of precipitates is less than 1.2%.

[0268] <Experimental Example 2: Determination of Dielectric Loss Tangent (Df)> (1) Fabrication of resin sheet A with a resin composition layer thickness of 40 μm: As a support, a polyethylene terephthalate film (Lintec "AL5", 38 μm thick) with a release layer was prepared. The varnish-like resin composition obtained in the examples and comparative examples was uniformly coated onto the release layer of this support, such that the thickness of the dried resin composition layer was 40 μm. Then, the resin composition was dried at 80°C to 100°C (average 90°C) for 2 minutes to obtain a resin sheet A comprising the support and the resin composition layer.

[0269] (2) Preparation of solidified material: The obtained resin sheet A was cured in an oven at 180°C for 90 minutes. The support was peeled off from the oven, thus obtaining the cured resin composition layer.

[0270] (3) Determination of dielectric loss tangent (Df): The cured material was cut into pieces 80 mm long and 2 mm wide. Using an Agilent Technologies HP8362B resonator, the dielectric loss tangent (Df value) was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23 °C via the resonant cavity perturbation method. Measurements were performed on two samples, and the average value was calculated.

[0271] <Experimental Example 3: Determination of Glass Transition Temperature (Tg)> The cured material obtained in Test Example 1(2) was cut into specimens approximately 5 mm wide and 15 mm long. Thermomechanical analysis was performed using a thermomechanical analysis apparatus (Rigaku, "Thermo Plus TMA8310"), employing the tensile load method. After mounting the specimens on the apparatus, the coefficient of thermal expansion (ppm) was measured twice consecutively under a load of 1 g and a heating rate of 5 °C / min. The first heating was to 200 °C, and the second to 260 °C. Based on the ppm values ​​from 25 °C to 150 °C in the second measurement, the average linear expansion coefficient (ppm / °C) was calculated. The glass transition temperature (Tg; °C) was then calculated from the second measurement.

[0272] <Experimental Example 4: Determination of Fracture Strength> The tensile strength of the cured material obtained in Test Example 1(2) was determined using an Orientec RTC-1250A tensile testing machine, and the breaking strength at 23°C was measured. The measurement was performed in accordance with JIS K7127. Five measurements were performed, and the average value of the first three values ​​from top to bottom was calculated.

[0273] <Experimental Example 5: Evaluation of Membrane Flexibility> (1) Evaluation of the fabrication of resin sheets: A glass cloth substrate epoxy resin double-sided copper-clad laminate (Panasonic "R5715ES", 0.7 mm thick, 255 mm square) was stacked on the untreated side of a PET film (50 μm thick, 240 mm square) treated with Lintec's release agent "1010". The four sides were then secured with polyimide adhesive tape (10 mm wide) (hereinafter referred to as "fixed PET film"). The resin composition obtained in the examples and comparative examples was applied to the release-treated side of the "fixed PET film" using an applicator, resulting in a dried resin composition layer thickness of 40 μm. The layer was dried at 70°C to 100°C (average 100°C) for 3 minutes. A resin sheet B, formed from the PET film and the resin composition layer, was obtained by removing the glass cloth substrate epoxy resin double-sided copper-clad laminate from the laminate.

[0274] (2) MIT Experiment: Resin sheet B was cut into test pieces 15 mm wide and 110 mm long. Using an MIT testing apparatus (MIT Flexural Fatigue Testing Machine "MIT-DA" manufactured by Toyo Seiki Co., Ltd.), according to JIS-C-5016, the number of flexural cycles until fracture of the resin composition layer in resin sheet B was measured under the following conditions: load 2.5 N, bending angle 90°, bending radius 1.0 mm, and bending speed 175 times / minute. Five samples were tested, and the average of the top three values ​​was calculated. The results were then judged according to the following criteria: 〇: The flexural strength is more than 100 times. ×: The number of folding cycles is less than 100.

[0275] <Experimental Example 6: Evaluation of the adhesion between the resin composition layer and the protective film> (1) Manufacturing of roll-shaped adhesive sheets with protective film: Under normal pressure, at 60℃, and with a pressing pressure of 0.06 kgf / cm² 2 Under certain conditions, a polypropylene film (manufactured by Oji Special Paper Co., Ltd., smooth side of "ALPHAN MA-411", 15μm thickness) as a protective film was laminated onto the resin composition layer side surface of the resin sheet B obtained above, thereby manufacturing a resin sheet with a protective film.

[0276] (2) Determination of the peel strength of the protective film relative to the resin composition layer: The resin sheets with protective films manufactured in the examples and comparative examples were cut into 30 mm wide and 100 mm long sections with the longitudinal direction as the length, to obtain test specimens. Double-sided adhesive tape (Nichiban Co., Ltd. "Nice Tack") with a width of 25 mm and a length of 95 mm was adhered to the support side surface of the obtained specimens, and then bonded to high-grade thick paper (Jitsuta Co., Ltd. "Kona Yuki 210 (Extra Thick)") cut into 27 mm wide and 100 mm long sections. One end of the protective film was peeled off and held in a clamp, and the load when peeling 30 mm of the protective film vertically at a speed of 50 mm / min at room temperature (23°C) was measured to determine the peel strength SB. A tensile testing machine (TSE Co., Ltd. "AC-50C-SL") was used for the measurement. The results were judged according to the following evaluation criteria: ○: 0.003~0.006 kgf / cm³ △: Exceeding 0.006 kgf / cm ×: Less than 0.003 kgf / cm.

[0277] [Table 2]

Claims

1. A resin composition comprising (A) a cyclic phosphazene compound represented by the following formula (1), (B) a maleimide resin, (C) a radical polymerizable compound, (E) an inorganic filler, and (F) a curing accelerator, the (C) radical polymerizable compound does not include a maleimide, wherein the content of the (E) inorganic filler is 60% by mass or more, relative to 100% by mass of nonvolatile components of the resin composition, in the formula (1), R 1 and R 2 (i) each independently represents a nitro group, an alkyl group or an alkoxy group having 1 to 8 carbon atoms optionally substituted with at least one selected from an alkyl group having 1 to 6 carbon atoms and an aryl group, and an aryl group or an aryloxy group having 6 to 20 carbon atoms optionally substituted with at least one selected from an alkyl group having 1 to 6 carbon atoms and an aryl group, or (ii) forms, together with each other, a saturated or unsaturated cyclic structure optionally substituted with an alkyl group having 1 to 6 carbon atoms or a carbonyl group; L represents a divalent heteroatom; a and b each independently represent an integer of 0 to 4; m each independently represents 0 or 1; n represents an integer of 3 to 8; the structures of the repeating units are each independent. the mass ratio of the (B) maleimide resin to the (C) radical polymerizable compound, that is, the mass of the (B) component / the mass of the (C) component is 0.6 to 1.9, 2. The resin composition according to claim 1, wherein, the (C) radical polymerizable compound does not include a maleimide. The (A) cyclic phosphazene compound is a particle having an average particle diameter of 1.5 μm or less.

3. The resin composition according to claim 1, wherein, The (A) cyclic phosphazene compound is a particle having an average particle diameter of 0.8 μm or less.

4. The resin composition according to claim 1, wherein, 5. The resin composition according to claim 1, wherein The (A) cyclic phosphazene compound is a particle having an average particle diameter of Da μm, The (E) inorganic filler has an average particle diameter of Db μm, Da / Db is 0.1 or more and 10 or less. Da / Db is 1.5 or less.

6. The resin composition according to claim 5, wherein, The (A) cyclic phosphazene compound has a melting point of 260°C or more.

7. The resin composition according to claim 1, wherein In the case where the first dissolution test is performed, the amount of the (A) cyclic phosphazene compound dissolved is 0.04 g or less, 8. The resin composition according to claim 1, wherein, The first dissolution test is a test in which the (A) cyclic phosphazene compound is dissolved in cyclohexanone 10 g by ultrasonic treatment at 25°C for 10 minutes. In the case where the second dissolution test is performed, the amount of the (A) cyclic phosphazene compound dissolved is 0.3 g or less, 9. The resin composition according to claim 1, wherein, The second dissolution test is a test in which the (A) cyclic phosphazene compound is dissolved in cyclohexanone 10 g by ultrasonic treatment at 70°C for 10 minutes. The content of the (A) cyclic phosphazene compound is less than 5% by mass, when the resin component of the resin composition is taken as 100% by mass.

10. The resin composition according to claim 1, wherein, The content of the (A) cyclic phosphazene compound is 0.3% by mass or more, when the resin component of the resin composition is taken as 100% by mass.

11. The resin composition according to claim 1, wherein The content of the (A) cyclic phosphazene compound is 0.1% by mass or more and 5% by mass or less, when the resin component of the resin composition is taken as 100% by mass.

12. The resin composition according to claim 1, wherein, The content of the (B) maleimide resin is 1% by mass or more and 40% by mass or less, relative to 100% by mass of nonvolatile components of the resin composition.

13. The resin composition according to claim 1, wherein, ​ 14. The resin composition according to claim 1, wherein, The content of the (C) radical polymerizable compound is 1% by mass or more and 40% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition.

15. The resin composition according to claim 1, wherein, Further comprising (D) a thermoplastic resin.

16. The resin composition according to claim 15, wherein, The content of the (D) thermoplastic resin is 0.8% by mass or more and 2.1% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition.

17. The resin composition according to claim 1, wherein, The content of the (E) inorganic filler is 60% by mass or more and 90% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition.

18. The resin composition according to claim 1, wherein, The content of the (F) curing accelerator is 0.01% by mass or more and 3.0% by mass or less, based on 100% by mass of the nonvolatile components in the resin composition.

19. The resin composition according to claim 1, wherein, The resin composition contains a ketone-based solvent.

20. The resin composition according to claim 1, wherein, The resin composition contains a solvent, The solvent contains a non-aromatic high-boiling-point solvent having no aromatic ring in the molecule and having a boiling point of 100°C or higher.

21. The resin composition according to claim 20, wherein, The content of the non-aromatic high-boiling-point solvent is 50% by mass or less, based on 100% by mass of the total amount of the solvent.

22. The resin composition of claim 20, wherein, The content of the non-aromatic high-boiling-point solvent is 8% by mass or less, based on 100% by mass of the total amount of the resin composition.

23. A resin sheet comprising a support and a resin composition layer formed on the support, The resin composition layer contains the resin composition according to any one of claims 1 to 22.

24. A cured product of the resin composition according to any one of claims 1 to 22.

25. A circuit substrate comprising a cured product of the resin composition according to any one of claims 1 to 22.

26. A semiconductor device comprising the circuit substrate according to claim 25.

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