Thermosetting maleimide resin compositions, films, prepregs, laminates, and printed circuit boards

Abstract

This invention provides a thermosetting maleimide resin composition, etc. It imparts excellent dielectric properties, low water absorption, and a high glass transition temperature even in the high-frequency region. The thermosetting maleimide resin composition contains (A) two or more maleimide compounds having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule, and (B) a reaction initiator, and the cured thermosetting maleimide resin composition has a dielectric loss tangent of 0.003 or less at 10 GHz and 40 GHz.

Description

Technical Field

[0001] This invention relates to thermosetting maleimide resin compositions, films, prepregs, laminates, and printed circuit boards. Prior Technology

[0002] In recent years, next-generation communication systems such as 5G (millimeter wave region of 26GHz~80GHz) have become popular. Furthermore, the development of even more advanced next-generation communication systems such as 6G has begun, striving to achieve higher speeds, larger capacities, and lower latency communication than current systems. To realize these communication systems, high-frequency materials in the 3GHz~80GHz range are needed, and as a noise countermeasure, transmission loss must be reduced. Transmission loss is the sum of conductor loss and dielectric loss. Reducing conductor loss requires low surface roughness of the metal foil used. On the other hand, since dielectric loss is proportional to the product of the square root of the relative permittivity and the dielectric loss tangent, it is necessary to develop insulating materials with excellent dielectric properties (low relative permittivity and low dielectric loss tangent) as insulating materials. In substrate applications, insulating materials with excellent dielectric properties, as described above, are required. Reactive polyphenylene ether (PPE) resin is used in rigid substrates, while liquid crystal polymers (LCP) and modified polyimide (MPI) with improved properties are used in flexible printed circuit boards (FPCs).

[0003] In contrast, some disclosed maleimide compounds (special maleimide compounds) that essentially use a dimer diamine backbone as the main resin for substrates have been disclosed. Unlike typical maleimide resins, special maleimide compounds, while possessing a low glass transition temperature (Tg) and a high coefficient of thermal expansion (CTE), also exhibit excellent dielectric properties, flexibility, and strong adhesion to metals, and are thermosetting resins. Therefore, they offer numerous advantages, including high potential for multilayering, and are thus subject to extensive research and development. However, the use of special maleimide compounds alone remains the primary approach. Furthermore, as mentioned above, since dielectric loss is proportional to the product of the square root of the relative permittivity and the dielectric loss tangent, reducing the dielectric loss tangent is even more important in materials used at high frequencies.

[0004] From the perspective of substrate dimensional stability, although it has been disclosed that other aromatic maleimide compounds with high Tg are used in combination with special maleimide compounds (Patent Document 5), aromatic maleimide compounds not only tend to deteriorate dielectric properties in the millimeter-wave region above 28 GHz, but also suffer from problems such as easy hygroscopicity, lack of compatibility, easy separation of cured products, and easy quality deviation. On the other hand, although the high Tg of special maleimide compounds can be achieved by using maleimide compounds that combine diamines other than dimer diamines (Patent Document 6), Patent Document 6 does not specifically mention the dielectric properties in the millimeter-wave region. In addition, it is known that maleimide compounds that combine dimer diamines and diamines other than dimer diamines have high viscosity, thus posing problems in terms of formability and embeddability. Existing technical documents Patent documents

[0005] [Patent Document 1]: Japanese Patent Application Publication No. 2016-131243 [Patent Document 2]: Japanese Patent Application Publication No. 2016-131244 [Patent Document 3]: International Publication No. 2016 / 114287 [Patent Document 4]: Japanese Patent Application Publication No. 2018-201024 [Patent Document 5]: International Publication No. 2016 / 114286 [Patent Document 6]: Japanese Patent Application Publication No. 2019-203122 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] Therefore, the object of the present invention is to provide a thermosetting maleimide resin composition that imparts excellent dielectric properties, low water absorption, and a high glass transition temperature to the cured product even in the high-frequency region. Furthermore, the object of the present invention is to provide a thermosetting maleimide resin composition that exhibits excellent dielectric properties even in the high-frequency region, and whose formability and embeddability are also improved. In addition, the object of the present invention is to provide uncured / cured films, prepregs, laminates, and printed circuit boards containing these thermosetting maleimide resin compositions. Problem Solving Methods

[0008] To solve the above problems, the inventors conducted repeated and in-depth research and found that the following thermosetting maleimide resin composition can achieve the above objectives, thus completing the present invention.

[0009] <1> A thermosetting maleimide resin composition, comprising, (A) Two or more maleimine compounds having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule, and (B) Reaction initiator, Furthermore, the dielectric loss tangent of the cured thermosetting maleimide resin composition at 10 GHz and at 40 GHz is less than 0.003. <2> according to <1> The thermosetting maleimide resin composition, Wherein, at least one of the components (A) is a maleimine compound (A-1) represented by formula (1), and at least another component (A) is a maleimine compound (A-2) represented by formula (3). (In formula (1), A is independently a tetravalent organic group with a cyclic structure, B is independently a divalent hydrocarbon group with 6 to 200 carbon atoms, Q is independently a divalent alicyclic hydrocarbon group with 6 to 60 carbon atoms, W is B or Q, at least one of B and W is a hydrocarbon group from a dimer acid skeleton, l is 1 to 100, m is 1 to 200, the order of the repeating units enclosed by m and l is not limited, and their bonding mode can be alternating, block or random.) (In formula (3), A is a tetravalent organic group with a cyclic structure, B is a divalent hydrocarbon group with 6 to 200 carbon atoms, and at least one of them is a hydrocarbon group from a dimer acid skeleton, and n is 0 to 100.) <3> according to <2> The thermosetting maleimide resin composition, In formulas (1) and (3), A is any one of the tetravalent organic groups represented by the following structural formulas. <4> according to <1> ~ <3> The thermosetting maleimide resin composition, Specifically, relative to the dielectric loss tangent at 10 GHz, the rate of change of the dielectric loss tangent of the cured thermosetting maleimide resin composition at 40 GHz is less than ±30%. <5> according to <1> The thermosetting maleimide resin composition, Among them, the reaction initiator of component (B) is an organic peroxide with a 1-hour half-life and a temperature of 140°C or higher. <6> according to <5> The thermosetting maleimide resin composition, It also contains a polymerization inhibitor as component (C). <7> An uncured film for substrate formation, It contains <1> ~ <6> The thermosetting maleimide resin composition. <8> A cured film for substrate formation, It contains <1> ~ <6> The cured product of the aforementioned thermosetting maleimide resin composition. <9> A prepreg, It contains <1> ~ <6> The thermosetting maleimide resin composition and fiber substrate. <10> A type of laminate, Its package <1> ~ <6> The cured product of the aforementioned thermosetting maleimide resin composition. <11> A printed circuit board, It contains <1> ~ <6> The cured product of the aforementioned thermosetting maleimide resin composition. The effects of the invention

[0010] The thermosetting maleimide resin composition of the present invention can impart cured products with excellent dielectric properties even in the high-frequency region, low water absorption, and high Tg. Furthermore, in one embodiment of the invention, it also exhibits excellent formability and embeddability. Therefore, the thermosetting maleimide resin composition of the present invention is suitable for uncured / cured films, particularly for uncured / cured films, prepregs, laminates and printed circuit boards used for substrate formation. Simple Explanation of the Diagram

[0011] [Figure 1] is a cross-sectional view showing an example of the prepreg of the present invention. [Figure 2] is a cross-sectional view showing an example of the laminate of the present invention. [Figure 3] is a cross-sectional view showing an example of the printed circuit board of the present invention. [Figure 4A] is a cross-sectional view of the copper-clad laminate used for evaluation in the transmission loss measurement. [Figure 4B] is a plan view of the copper-clad laminate used for evaluation in the transmission loss measurement. [Figure 5] is a cross-sectional view of the substrate after the tetrafluoroethylene-ethylene copolymer resin film has been removed after molding. Implementation

[0012] The present invention will now be described in more detail.

[0013] (A) Maleimine compounds having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule. The (A) component used in this invention is a maleicimine compound having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule, and the composition of this invention contains two or more of the maleicimine compounds.

[0014] The dimer acids mentioned here refer to liquid dicarboxylic acids with 36 carbon atoms, formed by the dimerization of 18-carbon unsaturated fatty acids from natural products such as plant oils, and primarily composed of dicarboxylic acids. Dimer acids do not have a single skeleton but possess various structures and exist in multiple isomers. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic cyclic (c), and polycyclic (d). In this specification, the dimer acid backbone refers to a group derived from a dimer diamine having a structure in which the carboxyl group of such a dimer acid is replaced by a primary aminomethyl group. That is, component (A) is preferably a component in which the dimer acid shown in (a) to (d) below has a group in which two carboxyl groups are replaced by methylene groups as the dimer acid backbone. Furthermore, from the viewpoint of heat resistance and reliability of the cured product, the hydrocarbon group from the dimer acid skeleton in the maleic imine compound of component (A) is more preferably a hydrocarbon group having a structure in which the carbon-carbon double bond in the hydrocarbon group from the dimer acid skeleton has been reduced by hydrogenation reaction.

[0015]

[0016] One of the components (A) is preferably a maleimide compound (A-1) represented by the following formula (1), and further, another component (A) is preferably a maleimide compound (A-2) represented by the following formula (3).

[0017] (A-1) (In formula (1), A is independently a tetravalent organic group with a cyclic structure, B is independently a divalent hydrocarbon group with 6 to 200 carbon atoms, Q is independently a divalent alicyclic hydrocarbon group with 6 to 60 carbon atoms, W is B or Q, at least one of B and W is a hydrocarbon group derived from a dimer acid skeleton, l is 1 to 100, and m is 1 to 200. In addition, the order of the repeating units enclosed in m and l is not limited, and their bonding mode can be alternating, block, or random.)

[0018] If the maleimide compound (A-1) represented by formula (1) above is used, it is a maleimide compound with superior dielectric properties compared to other general maleimide compounds containing multiple aromatic rings, both before and after curing. It also has strong adhesion to metal foils such as copper foil and a dimer acid backbone, and can form a composition with high Tg and high reliability. The maleimide compound represented by formula (1) can be used alone or in combination with two or more.

[0019] In addition, in the formula (1), A is independently represented as a tetravalent organic group having a cyclic structure, preferably any of the tetravalent organic groups represented by the following structural formula. (In the above structural formula, the bonding ends of the unbonded substituents are bonded to the carbonyl carbon that forms a cyclic amide structure in formula (1).)

[0020] Furthermore, in formula (1), B is independently a divalent hydrocarbon group having 6 to 200 carbon atoms, preferably 8 to 100, and more preferably 10 to 50. Preferably, one or more hydrogen atoms in the divalent hydrocarbon group are substituted by an alkyl or alkenyl group having 6 to 200 carbon atoms, preferably 8 to 100, and more preferably 10 to 50. The branched divalent hydrocarbon group can be either a saturated aliphatic hydrocarbon group or an unsaturated hydrocarbon group, and may also have an alicyclic or aromatic ring structure midway through the molecular chain. Specifically, branched divalent hydrocarbon groups can be exemplified by divalent hydrocarbon groups derived from two-terminal diamines called dimer diamines. Therefore, B is particularly preferred to be a branched divalent hydrocarbon group having two carboxyl groups respectively replaced by methylene groups in each dimer acid represented by (a) to (d) above.

[0021] Furthermore, in formula (1), Q is independently a divalent alicyclic hydrocarbon group with 6 to 60 carbon atoms, preferably a divalent alicyclic hydrocarbon group with 6 to 30 carbon atoms, more preferably an alicyclic hydrocarbon group with 6 to 20 carbon atoms, and even more preferably an alicyclic hydrocarbon group with 8 to 18 carbon atoms. As this alicyclic hydrocarbon group, it is preferably a hydrocarbon group having a cyclohexane skeleton. As an embodiment having this cyclohexane skeleton, it may be an embodiment having one cyclohexane ring, for example, as shown in formula (2) below, or an embodiment having multiple cyclohexane rings bonded by alkyl groups, or a polycyclic embodiment having a bridging structure. (In formula (2), R1 is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and x1 and x2 are independently numbers from 0 to 4.)

[0022] Specific examples of R1 can include hydrogen atoms, methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, and tributyl groups. Preferably, hydrogen atoms and methyl groups are used. It should be noted that each R1 can be the same or different. Furthermore, x1 and x2 are each independently a number from 0 to 4, preferably a number from 0 to 2. It should be noted that x1 and x2 can be the same or different.

[0023] As a specific example of Q, divalent alicyclic hydrocarbon groups represented by the following structural formula can be listed. (The unbonded substituents in the above structural formula are bonded to nitrogen atoms that form a cyclic amide structure in formula (1).)

[0024] In equation (1), W is B or Q. For W, the type of structural unit having B or Q is determined according to the different manufacturing methods.

[0025] In the formula (1), l is 1 to 100, preferably 1 to 60, and more preferably 2 to 50. m is 1 to 200, preferably 1 to 50, and more preferably 3 to 40. If m or l is too large, the fluidity will decrease, and the formability may deteriorate. The order of the repeating units enclosed by m and l is not limited, and their bonding mode can be alternating, block, or random, but from the viewpoint of easy high Tg scaling, block is preferred.

[0026] (A-2) (In formula (3), A is the same as in formula (1), and is independently a tetravalent organic group with a cyclic structure; B is independently a divalent hydrocarbon group with 6 to 200 carbon atoms, and at least one of them is a hydrocarbon group derived from a dimer acid skeleton. n is 0 to 100.)

[0027] If the maleimide compound (A-2) represented by formula (3) above is used, it exhibits superior dielectric properties compared to other general maleimide compounds containing multiple aromatic rings, both before and after curing. In particular, it effectively maintains its dielectric properties not only at high frequencies but also exhibits stronger adhesion to copper foil than when the maleimide compound represented by formula (1) is used alone, thus forming an excellent composition. The maleimide compound represented by formula (3) can be used alone or in combination with two or more compounds.

[0028] In the above formula (3), A is the same as A in the above formula (1), and independently represents a tetravalent organic group having a cyclic structure, preferably any of the tetravalent organic groups represented by the following structural formula. (The bonding ends of the unbonded substituents in the above structural formula are bonded to the carbonyl carbon that forms a cyclic amide structure in formula (3).)

[0029] Furthermore, in formula (3), B is independently a divalent hydrocarbon group having 6 to 200 carbon atoms, preferably 8 to 100, more preferably 10 to 50, and at least one of them is a hydrocarbon group derived from a dimer acid skeleton. As a dimer acid skeleton, it is preferably a dimer acid skeleton having two carboxyl groups substituted with methylene groups in each dimer acid represented by (a) to (d). Similarly, it is preferably a branched divalent hydrocarbon group having one or more hydrogen atoms in the divalent hydrocarbon group substituted with alkyl or alkenyl groups having 6 to 200 carbon atoms, preferably 8 to 100, more preferably 10 to 50. As a branched divalent hydrocarbon group, it can be either a saturated aliphatic hydrocarbon group or an unsaturated hydrocarbon group, and it can also have an alicyclic or aromatic ring structure in the middle of the molecular chain.

[0030] In the above formula (3), n is 0~100, preferably 0~60, and more preferably 0~50. If n is too large, the solubility and fluidity will decrease, and the formability may become worse.

[0031] There is no particular limitation on the number-average molecular weight of the maleimide compounds ((A-1) and (A-2)) of the two components (A), but from the viewpoint of operability of the composition, 800 to 50,000, more preferably 900 to 30,000, is preferred. In addition, component (A) may also contain other maleimide compounds besides (A-1) and (A-2). It should be noted that the number average molecular weight mentioned in this specification refers to the number average molecular weight converted from polystyrene as a standard substance, determined by gel permeation chromatography (GPC) under the following conditions.

[0032] [Measurement Conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.35 mL / min Detector: Differential Refractive Index Detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperHZ 4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ 3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ 2000(4.6mmI.D.×15cm×2) (All manufactured by TOSOH CORPORATION) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0033] The content of the two (A) components in the resin composition of the present invention is not particularly limited, but from the viewpoint of heat resistance and dimensional stability of the cured product, when the inorganic filler described later is not incorporated, the total content of all components other than the organic solvent in the case of a varnish is preferably 90% by mass or more and less than 100% by mass, more preferably 90 to 99% by mass. When the inorganic filler described later is incorporated, the total content of all components other than the organic solvent in the case of a varnish is preferably 10 to 90% by mass, more preferably 20 to 80% by mass. Furthermore, when both (A-1) and (A-2) are present, the preferred ratio, by mass, is (A-1):(A-2)=95:5~40:60, and more preferably (A-1):(A-2)=90:10~60:40.

[0034] (B) Reaction initiator The reaction initiator, which is component (B), is an ingredient added to promote the cross-linking reaction of the maleimide compound, which is component (A), and the reaction of the maleimide group in component (A) with the reactive groups. As component (B), any component that promotes cross-linking reactions is acceptable, without any particular restrictions. Examples include imidazoles, tertiary amines, quaternary ammonium salts, boron trifluoride amine complexes, organophosphorus compounds, organophosphonium salts, and other ionic catalysts; diallyl peroxides, dialkyl peroxides, peroxide carbonates, hydrogen peroxide, and other organic peroxides; and azoisobutyronitrile and other free radical polymerization initiators. In cases where component (A) alone promotes the reaction, or where the reactive groups other than component (A) described below have carbon-carbon double bond groups such as maleimino, alkenyl, and (meth)acrylic acid, the reactive groups are used, component (B) is preferably an organic peroxide and a free radical polymerization initiator. Examples of organic peroxides include diisopropylphenyl peroxide, tributyl benzoate peroxide, tripentyl benzoate peroxide, dibenzoyl peroxide, and dilauryl peroxide. Furthermore, when the reactive groups of the thermosetting resin other than component (A) that are capable of reacting with maleimide groups are epoxy, hydroxyl, or anhydride groups, basic compounds such as imidazoles and tertiary amines are preferred. Although imidazoles or amines can also be used in the homopolymerization of maleimide groups, very high temperatures are required in the case of imidazoles. Therefore, it should be noted that amines tend to have a very short service life. In one embodiment of the present invention, if an organic peroxide with a 1-hour half-life temperature of 140°C or higher is used as the reaction initiator for component (B), a composition with excellent formability (flowability) and embeddability is obtained. Examples of such organic peroxides with a 1-hour half-life temperature of 140°C or higher include di-(tert-butylperoxyisopropyl)benzene, di-tert-butyl peroxide, propylphenyl hydroperoxide, tert-butyl hydroperoxide, and tert-butylisopropylphenyl peroxide.

[0035] Relative to 100 parts by weight of component (A), the reaction initiator is preferably prepared in the range of 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight. Furthermore, when other thermosetting resins described later are incorporated into the composition, the reaction initiator is preferably prepared in the range of 0.05 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, relative to the total of 100 parts by weight of component (A) and other thermosetting resin components. If the reaction initiator exceeds the above range, there is a risk that the curing process during the molding of the maleimide resin composition may become very slow or fast, and therefore it is not preferred. Additionally, there is a risk that the balance between the heat resistance and moisture resistance of the resulting cured product may deteriorate. (B) The reaction initiator of component (B) can be used alone or in combination with two or more.

[0036] The cured thermosetting maleimide resin composition containing components (A) and (B) of the present invention exhibits dielectric loss tangents of 0.003 or less at both 10 GHz and 40 GHz. While the dielectric loss tangent can be reduced by incorporating inorganic fillers, such as silicon dioxide, which have low dielectric loss tangents, it is known that reducing the dielectric loss tangent of resin components such as components (A) and (B) is crucial, particularly as it strongly influences transmission loss in the millimeter-wave region. Preferably, the dielectric loss tangents at both 10 GHz and 40 GHz are 0.0025 or less. Furthermore, from the viewpoint of ease of circuit design, the rate of change of the dielectric loss tangent at 40 GHz relative to the 10 GHz dielectric loss tangent is preferably ±30% or less, more preferably ±25% or less. That is, as the rate of change, the value of [(40GHz dielectric loss tangent - 10GHz dielectric loss tangent) / 10GHz dielectric loss tangent × 100] is preferably -30% to +30%, more preferably -25% to +25%.

[0037] Other additives In the thermosetting maleimide resin composition of the present invention, various additives may be formulated as needed without impairing the effects of the present invention. Other additives are illustrated below.

[0038] (C) Polymerization inhibitors The thermosetting maleimide resin composition of the present invention can also be formulated as a polymerization inhibitor as component (C). The polymerization inhibitor is a component formulated to improve the storage stability and reactivity control of the thermosetting maleimide resin composition of the present invention; any effective inhibitor is acceptable and there are no particular limitations. In particular, as a reaction initiator for component (B), when using an organic peroxide with a 1-hour half-life temperature of 140°C or higher (B1), a polymerization inhibitor that can also be formulated as component (C) is preferred.

[0039] Examples of polymerization inhibitors include commonly used inhibitors such as catechol, resorcinol, and 1,4-hydroquinone, as well as 2-methylcatechol, 3-methylcatechol, 4-methylcatechol, 2-ethylcatechol, 3-ethylcatechol, 4-ethylcatechol, 2-propylcatechol, 3-propylcatechol, 4-propylcatechol, 2-n-butylcatechol, 3-n-butylcatechol, 4-n-butylcatechol, and 2-tert-butylcatechol. Alkyl catechols such as 3-tert-butylcatechol, 4-tert-butylcatechol, and 3,5-ditert-butylcatechol; and alkyl resorcinols such as 2-methylresorcinol, 4-methylresorcinol, 2-ethylresorcinol, 4-ethylresorcinol, 2-propylresorcinol, 4-propylresorcinol, 2-n-butylresorcinol, 4-n-butylresorcinol, 2-tert-butylresorcinol, and 4-tert-butylresorcinol. Alkyl hydroquinone compounds such as methyl hydroquinone, ethyl hydroquinone, propyl hydroquinone, and tributyl hydroquinone; phosphine compounds such as tributylphosphine, trioctylphosphine, tricyclohexylphosphine, and triphenylphosphine; phosphine oxide compounds such as trioctylphosphine oxide and triphenylphosphine oxide; phosphite compounds such as triphenylphosphite and trinonylphenylphosphite; hindered amine compounds such as 2,2,6,6-tetramethylpiperidin-1-oxy and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy; naphthalene compounds such as 1,4-dihydroxy-2-naphthalenesulfonate ammonium and 4-methoxy-1-naphthol; naphthoquinone compounds such as 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, and anthrone; phenolic antioxidants such as pyrogallol, phloroglucin, 2,6-di-tert-butyl-p-cresol, and 4,4'-butylene-bis(6-tert-butyl-m-cresol).

[0040] Relative to 100 parts by weight of component (A), the amount of polymerization inhibitor in component (C) is preferably 0.01 to 0.50 parts by weight, more preferably 0.02 to 0.45 parts by weight, and even more preferably 0.03 to 0.40 parts by weight. Furthermore, when the composition of the present invention contains a thermosetting maleimide resin having reactive groups capable of reacting with maleimide groups other than component (A) described below, the amount of the polymerization inhibitor in component (C) is preferably 0.01 to 0.70 parts by weight, more preferably 0.02 to 0.60 parts by weight, and even more preferably 0.03 to 0.50 parts by weight, relative to 100 parts by weight of the thermosetting maleimide resin component. In addition, component (C) can be used alone or in combination of two or more.

[0041] Thermosetting resins containing reactive groups capable of reacting with maleimide groups In this invention, a thermosetting resin having reactive groups capable of reacting with maleimide groups may also be added. As a thermosetting resin, its type is not limited, and examples include, for instance, epoxy resins, phenolic resins, melamine resins, organosilicone resins, cyclic propylene resins (represented by maleimide compounds other than component (A), urea-formaldehyde resins, thermosetting polypropylene resins, modified polyphenylene ether resins, thermosetting acrylic resins, and epoxy-organosilicone hybrid resins, etc., and various other resins other than component (A). Furthermore, as reactive groups capable of reacting with maleimide groups, examples include epoxy groups, maleimide groups, hydroxyl groups, acid anhydride groups, alkenyl groups such as allyl or vinyl groups, (meth)acrylic groups, and thiol groups.

[0042] From a reactivity point of view, the reactive groups of the thermosetting resin are preferably selected from epoxy, maleimide, hydroxyl and alkenyl groups, and more preferably alkenyl or (meth)acrylyl groups from a dielectric property point of view. However, in the total amount of thermosetting resins, the amount of thermosetting resin having reactive groups that can react with maleimine groups is 0 to 60% by mass, preferably 0 to 50% by mass.

[0043] Inorganic packing In this invention, inorganic fillers may be added as needed. Inorganic fillers are formulated to improve the strength and rigidity of the cured thermosetting maleimide resin composition of this invention and / or to adjust the coefficient of thermal expansion and the dimensional stability of the cured product. As inorganic fillers, those commonly formulated in epoxy resin compositions or organosilicon resin compositions can be used. Examples include, for instance, silica types such as spherical silica, fused silica, and crystalline silica; alumina; silicon nitride; aluminum nitride; boron nitride; barium sulfate; talc; clay; aluminum hydroxide; magnesium hydroxide; calcium carbonate; glass fiber; and glass particles. Furthermore, to improve dielectric properties, fluorinated resins, coating fillers, and / or hollow particles may be used, and to impart conductivity, conductive fillers such as metal particles, metal-coated inorganic particles, carbon fibers, and carbon nanotubes may be added. One type of inorganic filler may be used alone, or two or more may be used in combination. The amount of inorganic filler added relative to 100 parts by weight of component (A) can be 0 to 300 parts by weight, preferably 30 to 300 parts by weight.

[0044] There are no particular limitations on the average particle size and shape of the inorganic filler. In the case of forming films or substrates, spherical silicon dioxide with an average particle size of 0.5 to 5 µm is particularly preferred. It should be noted that the average particle size is the value obtained as the mass average value D50 (or median particle size) in particle size distribution determination by laser diffraction.

[0045] Furthermore, to improve properties, the inorganic filler is preferably surface-treated with a silane coupling agent having an organic group capable of reacting with a maleimide group. Examples of such silane coupling agents include alkoxysilanes containing epoxy groups, alkoxysilanes containing amino groups, alkoxysilanes containing (meth)acrylamide groups, and alkoxysilanes containing alkenyl groups. As the aforementioned silane coupling agent, alkoxysilanes containing (meth)acrylyl groups and / or alkoxysilanes containing amino groups are preferred. Specifically, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane, etc., can be used.

[0046] other In addition, it can also be formulated with nonfunctional silicone oils, reactive diluents, thermoplastic resins, thermoplastic elastomers, organic synthetic rubbers, photosensitizers, light stabilizers, flame retardants, pigments, dyes, adhesive additives, ion trapping materials, etc. In addition, the aforementioned surface-treated inorganic fillers, such as epoxy-containing alkoxysilanes, amino-containing alkoxysilanes, (meth)acrylyl-containing alkoxysilanes, and alkenyl-containing alkoxysilanes, can also be separately formulated into the thermosetting maleimide resin composition of the present invention. Specific inorganic fillers can also be the same as those described above.

[0047] The thermosetting maleimide resin composition of the present invention can be dissolved in an organic solvent for varnishing. By varnishing this composition, film formation is facilitated, and it is also easy to coat and impregnate fiber substrates such as glass cloth made of E-glass, low-dielectric-constant glass, or quartz glass. For the organic solvent, any thermosetting resin having reactive groups that react with maleimide groups, such as component (A), component (B), and other additives, can be used without limitation. Examples include anisole, tetrahydronaphthalene, mesitylene, xylene, toluene, methyl ethyl ketone (MEK), tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, etc. One or more of these solvents can be used alone or in combination.

[0048] [Manufacturing Method] As a method for manufacturing the thermosetting maleimide resin composition of the present invention, examples include mixing component (A) and component (B), as well as other additives added as needed, using a planetary mixer (manufactured by Inoue Manufacturing Co., Ltd., Japan) or a THINKY CONDITIONING MIXER (manufactured by THINKY CORPORATION, Japan).

[0049] [Uncured resin film / Cured resin film] Regarding this thermosetting maleimide resin composition, by applying the varnish to a substrate and allowing the organic solvent to evaporate, an uncured resin sheet or uncured resin film (hereinafter also referred to as "uncured film") is formed, and / or, further by curing it, a cured resin sheet or cured resin film (hereinafter also referred to as "cured film") can be formed. The following examples illustrate methods for manufacturing sheets and films, but are not limited to these methods.

[0050] For example, after applying a thermosetting maleimide resin composition (varnish) dissolved in an organic solvent to a substrate, the organic solvent is usually removed by heating at a temperature of 80°C or higher, preferably 100°C or higher, for 0.5 to 20 minutes, and then further heated at a temperature of 130°C or higher, preferably 150°C or higher, for 0.5 to 10 hours, thereby forming a maleimide resin cured film with a flat surface and firmness. While the temperatures in the drying process for removing organic solvents and the subsequent heat curing process can be kept constant, it is preferable to gradually increase the temperature. By using this method, organic solvents can be effectively removed from the composition, and the curing reaction of the resin can be promoted more effectively. There are no particular restrictions on the application method of varnish, and methods such as using a spin coater, slot coater, sprayer, dip coater, and bar coater can be listed.

[0051] As the substrate, common substrates can be used, such as polyolefin resins like polyethylene (PE) resin, polypropylene (PP) resin, and polystyrene (PS) resin; and polyester resins like polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, and polycarbonate (PC) resin. Furthermore, the surface of these substrates can be subjected to a demolding treatment. While there is no particular limitation on the coating thickness, the thickness after solvent removal by distillation is in the range of 1 to 100 μm, preferably in the range of 3 to 80 μm. Furthermore, a cover film can be used on the coating.

[0052] Alternatively, the components can be premixed and the mixture can be extruded into sheets or films using a melt mixer to prepare uncured or cured films.

[0053] The cured coating obtained by curing the thermosetting maleimide resin composition of the present invention exhibits excellent heat resistance, mechanical properties, electrical properties, adhesion to substrates, and solvent resistance, as well as a low dielectric constant. Therefore, for example, it can be applied not only to semiconductor devices—specifically, to passivation or protective films on the surface of semiconductor elements, connection protective films at the junctions of diodes and transistors, alpha-ray shielding films for VLSI, interlayer insulating films, ion implantation masks, etc.—but also to conformal coatings for printed circuit boards, alignment films for liquid crystal surface elements, protective films for glass fibers, and surface protective films for solar cells. Furthermore, it can be applied to a wide range of applications, including paste compositions for printing in which inorganic fillers have been incorporated into the thermosetting maleimide resin composition, and conductive paste compositions incorporating conductive fillers.

[0054] Furthermore, since it can form a film or sheet in its uncured state, possesses self-adhesive properties, and exhibits excellent dielectric characteristics, it is particularly suitable for multilayer films used in the formation of substrates, such as for rigid substrates, and bonding films used in the formation of flexible printed circuit boards (FPCs), as well as uncured films or cured films used in the formation of substrates. Additionally, the cured resin film can also be used as a cover layer film.

[0055] Alternatively, a varnished thermosetting maleimide resin composition can be impregnated onto a fiber substrate such as glass cloth made of E-glass, low-dielectric-constant glass, or quartz glass to remove organic solvents, resulting in a semi-cured state, which can then be used as a prepreg. Furthermore, by laminating this prepreg with copper foil, laminates and printed circuit boards containing high-precision multilayers can be manufactured.

[0056] [Prepreg] Figure 1 shows a cross-sectional view of a prepreg according to one embodiment of the present invention. The prepreg 1 comprises a thermosetting maleimide resin composition 2 and a fiber substrate 3. The thermosetting maleimide resin composition 2 is the aforementioned thermosetting maleimide resin composition or a semi-cured product of the resin composition. It should be noted that a semi-cured product refers to the intermediate state of a resin composition that has been cured to the point where it can be further cured. That is, a semi-cured product is a partially cured state of the resin composition, also known as a B-stage product. On the other hand, the uncured state is sometimes referred to as the A-stage. That is, the thermosetting maleimide resin composition 2 can be either the A-stage or the B-stage thermosetting maleimide resin composition.

[0057] As described above, the fiber substrate 3 can include E-glass, low-dielectric glass, quartz glass, and further examples include S-glass and T-glass. While the type of glass used is not critical, from the viewpoint of maximizing the properties of the thermosetting maleimide resin composition, quartz glass cloth with low dielectric properties is preferred. It should be noted that the thickness of the fiber substrate is generally, for example, 0.01 mm or more and 0.3 mm or less.

[0058] In manufacturing the prepreg 1, the thermosetting maleimide resin composition 2 is preferably formed as a varnish-like resin varnish for impregnating the fiber substrate 3, which serves as the substrate for forming the prepreg. Such a varnish-like resin composition (resin varnish) is prepared, for example, in the following manner. First, the components of the resin composition that are soluble in an organic solvent are added to the organic solvent and dissolved. Heating may be performed at this time if necessary. Then, components insoluble in the organic solvent, such as inorganic fillers as needed, are added, and the mixture is dispersed to a given dispersion state using a ball mill, bead mill, planetary mixer, roller mill, etc., thereby preparing a varnish-like resin composition (resin varnish). The organic solvent used herein is not particularly limited as long as it does not hinder the curing reaction. Examples include, for instance, toluene, methyl ethyl ketone (MEK), xylene, and anisole.

[0059] As a method for manufacturing prepreg 1, examples include, for instance, impregnating a thermosetting maleimide resin composition 2, for example, with a varnish-like thermosetting maleimide resin composition 2 and then drying it. The thermosetting maleimide resin composition 2 is impregnated into the fiber substrate 3 by impregnation and coating. Impregnation can be repeated multiple times as needed. Furthermore, by repeatedly impregnating with various resin compositions of different compositions and concentrations, the desired composition and impregnation amount can eventually be adjusted. The fiber substrate 3 impregnated with the thermosetting maleimide resin composition (resin varnish) 2 is heated under desired heating conditions, for example, at 80°C to 180°C for 1 minute to 20 minutes. By heating, a prepreg 1 is obtained comprising the thermosetting maleimide resin composition 2 in a pre-cured (A-stage) or semi-cured (B-stage) state. It should be noted that the heating process causes the organic solvents to evaporate from the resin varnish, thereby reducing or removing the organic solvents.

[0060] [Laminated Board] A laminate relating to one embodiment of the present invention is a laminate consisting of an insulating layer comprising a cured product of the aforementioned thermosetting maleimide resin composition, or an insulating layer consisting of a cured product of the aforementioned thermosetting maleimide resin composition and layers other than the insulating layer. A commonly known laminate is a metal-clad laminate, the cross-sectional view of which is shown in FIG2. The metal-clad laminate 11 has an insulating layer 12 comprising a cured product of the aforementioned thermosetting maleimide resin composition or a cured product of the aforementioned thermosetting maleimide resin composition, and metal foils 13 on both sides of the insulating layer 12. While FIG2 illustrates a double-sided metal-clad laminate with metal foils 13 on both sides of the insulating layer 12, it is also possible to have a single-sided metal-clad laminate with metal foils 13 on only one side of the insulating layer 12. Furthermore, the insulating layer 12 can be an insulating layer composed of a cured product of the thermosetting maleimide resin composition, an insulating layer composed of a cured product of the prepreg 1, or an insulating layer laminated with multiple cured products of the prepreg 1. Additionally, the thickness of the metal foil 13 varies depending on the required performance of the final circuit board and is not particularly limited. The thickness of the metal foil 13 can be appropriately set according to the desired purpose, for example, preferably 1 to 70 µm. Furthermore, examples of the metal foil 13 include, for example, copper foil and aluminum foil. If the metal foil is thin, to improve operability, it can also be a carrier-supported copper foil with a release layer and a carrier.

[0061] As for the method of manufacturing such a laminate, any general manufacturing method is acceptable, and there are no particular limitations. For example, when using prepreg, a method can be listed as manufacturing a laminate by preparing one or more overlapping pieces of prepreg 1 (Fig. 1), further overlapping copper foil or other metal foil 13 on both sides or one side of it, and then heating and pressing to form a laminate.

[0062] Printed Circuit Board One embodiment of the present invention provides a printed circuit board containing a cured product of the thermosetting maleimide resin composition. As an example, FIG. 3 shows a cross-sectional view of a printed circuit board manufactured using the laminate, particularly the metal-clad laminate shown in FIG. 2. As described above, the insulating layer 12 of the metal-clad laminate used in the manufacture of the printed circuit board can also be an insulating layer manufactured using the prepreg. The printed circuit board 21 can be manufactured using known methods by performing circuit forming processes such as hole-making, metal plating, and metal foil etching, as well as multilayer bonding processes, relative to the metal-clad laminate 11.

[0063] [Example] The present invention will be specifically described below with examples and comparative examples, but the present invention is not limited to the following examples.

[0064] The components used in the examples and comparative examples are represented as follows.

[0065] (A-1) Maleimine compound (A-1-1): A number-average molecular weight of bismaleimide compounds (BMI-2500, manufactured by Designer Molecules Inc.) containing hydrocarbon groups derived from a dimer acid backbone, expressed as follows: 5000. -C36H70- indicates a structure derived from a dimer acid backbone. m≈5 (average), l≈1 (average) (A-1-2): The number-average molecular weight of the bismaleimide compound (SLK-2600, manufactured by Shin-Etsu Chemical Industry, Japan) containing hydrocarbon groups derived from the dimer acid backbone, expressed by the following formula: 6000 -C36H70- indicates a structure derived from a dimer acid backbone. m≈5 (average), l≈1 (average)

[0066] (A-2) Maleimine compounds (A-2-1): A number-average molecular weight of the bismaleimine compound (BMI-1400, manufactured by Designer Molecules Inc.) containing hydrocarbon groups derived from the dimer acid backbone, expressed as follows: 1700. -C36H70- indicates a structure derived from a dimer acid backbone. n≈2 (average) (A-2-2): A quantity-average molecular weight of bismaleimide compounds (trade name: BMI-3000J, manufactured by Designer Molecules Inc.) containing hydrocarbon groups derived from a dimer acid backbone, expressed as follows: 5000. -C36H70- indicates a structure derived from a dimer acid backbone. n≈5 (average) (A-2-3): Quantity average molecular weight of bismaleimine compounds (BMI-1500, manufactured by Designer Molecules Inc.) containing hydrocarbon groups derived from a dimer acid backbone, expressed as follows: 2200 -C36H70- indicates a structure derived from a dimer acid backbone. n≈2 (A-2-4): A quantity of bismaleimine compounds (trade name: BMI-5000, manufactured by Designer Molecules Inc.) containing hydrocarbon groups derived from a dimer acid backbone, expressed as follows, with an average molecular weight of 10,000. -C36H70- indicates a structure derived from a dimer acid backbone. n≈8

[0067] (A-3) Maleimine compounds used in comparative examples (A-3-1): 1,6-Dimaleimide-(2,2,4-trimethyl)hexane (trade name: BMI-TMH, manufactured by Daiwa Chemical Industries, Ltd., Japan) (A-3-2): 4,4'-Diphenylmethane bismaleimide (trade name: BMI-1000, manufactured by Daiwa Kasei Corporation, Japan) (A-3-3): Biphenylaryl maleimide compound (trade name: MIR-3000, manufactured by Nippon Kayaku Co., Ltd.) Quantity average molecular weight: 670

[0068] (B) Reaction initiator (B-1): Diisopropylphenyl peroxide (trade name: PERCUMYL D, manufactured by Nippon Oil Co., Ltd., Japan, 1-hour half-life temperature 135.7°C) (B1-1): Ditert-tert-butylperoxide (trade name: Trigonox B, manufactured by KAYAKU NOURYON CORPORATION, 1-hour half-life temperature 147°C) (B1-2): Di-(tertiary butylperoxyisopropyl)benzene (trade name: Perkadox 14S-FL, manufactured by KAYAKU NOURYON CORPORATION, 1-hour half-life temperature 141°C) (B-2): Laurox peroxide (trade names: Laurox, manufactured by KAYAKU NOURYON CORPORATION, 1-hour half-life temperature 79°C)

[0069] (C) Polymerization inhibitors (C-1)2,6-Di-tertiary-butyl-p-cresol (trade name: BHT Swanox, manufactured by Nippon Seiko Chemical Co., Ltd.)

[0070] Inorganic packing Spherical silica with an average particle size of 0.5µm (trade name: SO-25R, manufactured by Admatechs Co., Ltd.)

[0071] [Examples 1-8, Comparative Examples 1-12] As the (B) reaction initiator, (B-1): diisopropylphenyl peroxide was used to prepare a resin composition as follows, and the composition was evaluated. <Preparation and Appearance of Varnish> Following the preparation methods in Tables 1 and 2, the components shown in Tables 1 and 2 were added to a 500 mL four-necked flask equipped with a serpentine condenser and a stirrer, and stirred at 50°C for 2 hours to obtain a varnish-like resin composition. The appearance of the varnish-like resin composition was visually confirmed. A transparent varnish was rated ○; a cloudy but unseparated varnish was rated △; and a completely separated varnish was rated ×, and these were recorded in Table 1 or Table 2. Varnishes rated × were not further evaluated. However, for varnish-like resin compositions containing inorganic fillers, visual confirmation was not possible due to the inorganic fillers; therefore, resin compositions for which appearance evaluation was not possible were recorded as "-" in Table 1 or Table 2.

[0072] <Preparation of Uncured and Cured Films> In preparing the varnish according to the above steps, the varnish-like thermosetting maleimide resin compositions of Examples 1-8, Comparative Examples 1-8 and 10-12, which did not undergo varnish separation, were coated onto a PET film with a thickness of 38 µm using a roller coater and dried at 120°C for 10 minutes to obtain an uncured resin film with a thickness of 50 µm. This uncured resin film was placed on a 100 µm thick tetrafluoroethylene-ethylene copolymer resin film (manufactured by AGC Corporation, product name: AFLEX) and cured at 180°C for 2 hours to obtain a cured resin film.

[0073] <Relative permittivity and dielectric loss tangent> Using the cured resin film, a network analyzer (manufactured by Keysight Technologies, Inc., E5063-2D5) and a stripline (manufactured by Keycom Corporation) were connected to measure the relative permittivity and dielectric loss tangent of the cured resin film at frequencies of 10 GHz and 40 GHz. Furthermore, based on the measurement results, the degree of change in the dielectric loss tangent at 40 GHz relative to that at 10 GHz was calculated.

[0074] Glass transition temperature The glass transition temperature (Tg) of the cured resin film was determined using a DMA-800 fabricated by TA Instruments.

[0075] <Moisture absorption rate> The cured resin film was cut into 80mm×80mm pieces and placed in a constant temperature bath at 85℃ and 85% humidity for 24 hours. The moisture absorption rate was determined by the weight of the film before and after moisture absorption.

[0076] <Peel strength> A glass slide measuring 75 mm in length, 25 mm in width, and 1.0 mm in thickness was prepared. The uncured resin composition side of the PET film-coated film (without the PET substrate attached) was placed on one side of the glass slide, and lamination was performed at 100°C, 0.3 MPa pressure, and 60 seconds. After lamination, the PET substrate was peeled off, and an 18 µm thick copper foil (manufactured by Mitsui Metals Corporation, Japan, Rz: 0.6 µm) was placed on the resin composition side. Lamination was then performed at 100°C, 0.3 MPa pressure, and 60 seconds. Following lamination, the film was cured at 180°C for 2 hours to prepare an adhesion test piece. To evaluate adhesion, the 90° peel strength (kN / m) of each adhesion test piece was measured at a temperature of 23°C and a tensile speed of 50 mm / min, according to JIS-C-6481 "Test method for copper-clad laminates for printed circuit boards".

[0077] <Evaluation of substrate fabrication and measurement of transmission loss> After impregnating the varnish-like resin compositions obtained by formulating Examples 1, 2, 1, 2, 5, 6, 11, and 12 into quartz glass cloth (SQX-2116C, manufactured by Shin-Etsu Chemical Industry Co., Ltd., Japan), prepregs were obtained by drying at 120°C for 5 minutes. At this time, the content (resin content) of the thermosetting maleimide resin composition containing inorganic fillers was adjusted to approximately 55% by mass. In each example, two prepregs were prepared, and the resulting prepregs were laminated in an overlapping manner. Then, a copper foil (manufactured by Mitsui Metals Co., Ltd., Japan, Rz: 0.6µm) with a thickness of 18µm was overlapped on both sides of the prepregs. Copper-clad laminates for evaluation were prepared under the conditions of 180°C, 2 hours and 3MPa. Next, the single-sided copper foil of the obtained copper-clad laminate used for evaluation was etched to prepare a stripline with a length of 10 cm and a linewidth of 100 µm or more but less than 200 µm. Figures 4A and 4B show the cross-sectional and planar views of the copper-clad laminate used for evaluation in the transmission loss measurement, respectively. With a linewidth of 50 Ω impedance, the transmission loss at 10 GHz and 40 GHz was measured using a network analyzer (manufactured by Keysight Technologies) at an environment of 25°C and 50% humidity. It should be noted that in Tables 1 and 2, examples where this measurement was not performed are recorded as "-".

[0078] [Table 1]

[0079] [Table 2] *Two inversion points were observed in the glass transition temperature determination of Comparative Example 8. **Comparative Example 12: Due to the difficulty in handling the prepreg and insufficient adhesion to the copper foil, the resulting copper-clad laminate had poor appearance.

[0080] As a reaction initiator (B), an organic peroxide with a 1-hour half-life temperature of 140°C or higher (B1) was used to prepare the following resin composition, and the composition was evaluated. [Examples 9-13, Comparative Examples 13-22] <Preparation and appearance of varnish> According to the preparation of Tables 3 and 4, each component shown in Tables 3 and 4 was added into a 500 mL four-necked flask equipped with a serpentine condenser and a stirring device, and stirred at 50°C for 2 hours to obtain a varnish-like resin composition.

[0081] <Preparation of Uncured and Cured Films> In preparing the varnish according to the above steps, the varnish-like thermosetting maleimide resin compositions of Examples 9-13 and Comparative Examples 13-22, which did not undergo varnish separation, were coated onto a PET film with a thickness of 38 µm using a roller coater and dried at 120°C for 10 minutes to obtain an uncured resin film with a thickness of 50 µm. This uncured resin film was placed on a 100 µm thick tetrafluoroethylene-ethylene copolymer resin film (manufactured by AGC Corporation, product name: AFLEX) and cured at 180°C for 2 hours to obtain a cured resin film.

[0082] <Relative permittivity and dielectric loss tangent> Using the cured resin film, a network analyzer (manufactured by Keysight Technologies, Inc., E5063-2D5) and a stripline (manufactured by Keycom Inc.) were connected to measure the relative permittivity and dielectric loss tangent of the cured resin film at frequencies of 10 GHz and 40 GHz.

[0083] <Peel strength> A glass slide measuring 75 mm in length, 25 mm in width, and 1.0 mm in thickness was prepared. The uncured resin composition side of the PET film-coated film (without the PET substrate attached) was placed on one side of the glass slide, and lamination was performed at 100°C, 0.3 MPa pressure, and 60 seconds. After lamination, the PET substrate was peeled off, and an 18 µm thick copper foil (manufactured by Mitsui Metals Corporation, Japan, Rz: 0.6 µm) was placed on the resin composition side. Lamination was then performed at 100°C, 0.3 MPa pressure, and 60 seconds. Following lamination, the film was cured at 180°C for 2 hours to prepare an adhesion test piece. To evaluate adhesion, the 90° peel strength (kN / m) of each adhesion test piece was measured at a temperature of 23°C and a tensile speed of 50 mm / min, according to JIS-C-6481 "Test method for copper-clad laminates for printed circuit boards".

[0084] <Formability (Flowability)> Two 100mm×100mm×50µm uncured films were overlapped and laminated, and then a 105mm×105mm×18µm thick copper foil (manufactured by Mitsui Metals, Japan, Rz: 0.6µm) was overlapped on both sides. Next, a tetrafluoroethylene-ethylene copolymer resin film (manufactured by AGC, Japan, product name: AFLEX) was overlapped on the side of the copper foil without the uncured film. The process was then carried out at 180°C for 2 hours and 3MPa. At this point, resin overflow of less than 2mm was rated ○, resin overflow of more than 2mm but less than 5mm was rated △, resin overflow of more than 5mm was rated □, and resin overflow of less than 2mm, but ultimately not reaching the copper foil end face, was rated ×.

[0085] <Embeddedness> An evaluation substrate measuring 95mm × 95mm × 0.44mm (a laminate of a 0.4mm thick glass epoxy resin substrate and two 18µm copper foil sheets) was prepared. Only the copper foil in the central 50mm square area of ​​the substrate was etched, thus preparing an evaluation substrate with a circuit of L / S = 75 / 75µm. An uncured film measuring 100mm × 100mm × 50µm was overlapped on the circuit formation surface of the evaluation substrate, and then a tetrafluoroethylene-ethylene copolymer resin film (manufactured by AGC Corporation, Japan, product name: AFLEX) was overlapped on top. The laminate was then formed at 180°C for 2 hours and 3MPa. The cross-section of the laminate was observed under a microscope. Cases with no voids were rated as ○, cases with 1-3 voids as △, cases with 4 or more voids as □, and unfilled cases as ×. Figure 5 shows a cross-sectional view of the substrate after the tetrafluoroethylene-ethylene copolymer resin film was removed following the forming process.

[0086] [Table 3]

[0087] [Table 4] *Even though the pressure was reduced to 0.5 MPa, the overflow problem was not improved. Due to severe surface stickiness, an uncured film could not be obtained; therefore, only the relative permittivity and dielectric loss tangent were measured.

[0088] 1: Prepreg 2: Thermosetting maleimide resin composition 3: Fiber substrate 11: Metal-clad laminate 12: Insulation layer 13:Metal foil 21: Printed Circuit Board 22: Circuit Layer 31: Copper-clad laminate used for evaluation 41: Cured product of thermosetting maleimide resin composition 42: Glass epoxy board 43: The remaining copper foil portion (circuit) after edge grinding.

Claims

1. A thermosetting maleimide resin composition comprising, (A) two or more maleimide compounds having one or more hydrocarbon groups derived from a dimer acid backbone in one molecule, and (B) a reaction initiator, wherein, (A) At least one of the components is a maleimine compound (A-1) represented by formula (1), and at least another of the components is a maleimine compound (A-2) represented by formula (3). In formula (1), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group having 6 to 200 carbon atoms, Q is a divalent alicyclic hydrocarbon group represented by the following structural formula, the bonding end of the unbonded substituent in the above structural formula is a bonding end bonded to the nitrogen atom forming the cyclic nitrile structure in formula (1), W is B or Q, at least one of B and W is a hydrocarbon group from a dimer acid skeleton, l is 1 to 60, m is 1 to 50, the order of the repeating units enclosed in m and l is not limited, and their bonding mode is alternating, block, or random. In formula (3), A is independently a tetravalent organic group having a cyclic structure, B is independently a divalent hydrocarbon group with 6 to 200 carbon atoms, and at least one of them is a hydrocarbon group from a dimer acid skeleton, n is 0 to 60, wherein A in formulas (1) and (3) is any one of the tetravalent organic groups represented by the following structural formula, wherein the reaction initiator of component (B) is an organic peroxide with a 1-hour half-life temperature of 140°C or higher, and the dielectric loss tangent of the cured thermosetting maleimide resin composition at 10 GHz and 40 GHz is 0.003 or less, and the change rate of the dielectric loss tangent of the cured thermosetting maleimide resin composition at 40 GHz relative to the dielectric loss tangent at 10 GHz is ±30% or less.

2. The thermosetting maleimide resin composition according to claim 1, wherein, It also contains a polymerization inhibitor as component (C).

3. An uncured film for substrate formation, comprising the thermosetting maleimide resin composition of claim 1.

4. A cured film for substrate formation, comprising a cured product of the thermosetting maleimide resin composition of claim 1.

5. A prepreg comprising the thermosetting maleimide resin composition of claim 1 and a fiber substrate.

6. A laminate comprising a cured product of the thermosetting maleimide resin composition of claim 1.

7. A printed circuit board comprising a cured product of the thermosetting maleimide resin composition of claim 1.

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