Maleimide resin, resin composition, cured product, sheet, laminate, and printed wiring board

Abstract

The maleimide resin according to the present invention is a maleimide resin obtained by reacting a tetracarboxylic dianhydride (a1) containing a tetracarboxylic dianhydride having a fluorene skeleton, an amine (a2) containing a dimer diamine and an amine having a biphenyl skeleton, and maleic anhydride (a3).

Description

Technical Field

[0001] This invention relates to a maleimide resin, resin composition, cured product, sheet, laminate, and printed circuit board. Background Technology

[0002] Printed circuit boards and multilayer circuit boards using printed circuit boards are used in mobile communication devices such as mobile phones and smartphones, their base station devices, network-related electronic equipment such as servers / routers, and large computers.

[0003] In recent years, high-frequency electrical signals have been used in these products for high-speed transmission / processing of large amounts of information. However, high-frequency signals are very easy to attenuate. Therefore, in order to suppress transmission loss, insulating materials with excellent dielectric properties are required as insulating materials used in the aforementioned printed circuit boards and multilayer circuit boards.

[0004] As the aforementioned insulating material, epoxy resin compositions disclosed in Patent Documents 1 to 3 are known. Patent Document 1 discloses an epoxy resin composition containing epoxy resin, an active ester compound, and a triazine-containing cresol phenolic varnish resin, which is effective for achieving low dielectric loss tangent. Furthermore, Patent Documents 2 and 3 disclose resin compositions with epoxy resin and an active ester compound as essential components that can form cured products with low dielectric loss tangent, making them useful as insulating materials. However, it has been found that these epoxy resin compositions are unsuitable for high-frequency band applications.

[0005] On the other hand, Patent Document 4 reports a resin film composed of a resin composition exhibiting excellent dielectric properties (low relative permittivity and low dielectric loss tangent). This resin composition contains a bismaleimide resin with long-chain alkyl groups and a curing agent as a non-epoxy material. However, bismaleimide resins composed solely of long-chain alkyl diamines suffer from low Tg and low elastic modulus.

[0006] Previous technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2011-132507 Patent Document 2: Japanese Patent Application Publication No. 2015-101626 Patent Document 3: Japanese Patent Application Publication No. 2017-210527 Patent Document 4: International Publication No. 2016 / 114287 Summary of the Invention

[0007] The technical problem to be solved by the invention The present invention aims to provide a novel maleimide resin. A further objective of the present invention is to provide a maleimide resin capable of forming a cured product that maintains a low dielectric constant and low dielectric loss tangent while exhibiting high elastic modulus and high Tg, and excellent toughness. Another objective of the present invention is to provide a resin composition, cured product, sheet, laminate, and printed circuit board using the aforementioned maleimide resin.

[0008] means for solving technical problems The present invention provides the following maleimide resin, resin composition, cured product, sheet, laminate and printed circuit board.

[0009] [1] A maleimide resin, which is a maleimide resin formed by reacting tetracarboxylic dianhydride (a1), amine (a2) and maleic anhydride (a3), wherein the tetracarboxylic dianhydride (a1) comprises tetracarboxylic dianhydride having a fluorene skeleton, and the amine (a2) comprises dimer diamine and amine having a biphenyl skeleton.

[0010] [2] According to the maleimide resin described in [1] above, wherein, The aforementioned tetracarboxylic acid dianhydrides with a fluorene skeleton contain at least one of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.

[0011] [3] According to the maleimide resin described in [1] or [2] above, wherein, The aforementioned amines having a biphenyl skeleton contain at least one of 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-2,2'-diethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-diethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetramethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetraethylbiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, and 4,4'-diamino-3,3'-dimethoxybiphenyl.

[0012] [4] The maleimide resin according to any one of [1] to [3] above, wherein, The above-mentioned dimer diamine contains at least one of the compounds represented by the following general formula (1) and the compounds represented by the following general formula (2).

[0013] [In equations (1) and (2), m, n, p, and q represent integers greater than 1 selected in the manner of m+n=6~17 and p+q=8~19, respectively. The bonds represented by dashed lines refer to carbon-carbon single bonds or carbon-carbon double bonds. Among them, when the bonds represented by dashed lines are carbon-carbon double bonds, equations (1) and (2) have the following structure: the structure obtained by subtracting 1 from the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond as shown in equations (1) and (2).] [5] The maleimide resin according to any one of [1] to [4] above, wherein, The weight-average molecular weight is 3,000 to 40,000.

[0014] [6] A resin composition comprising the maleimide resin described in any one of [1] to [5] above.

[0015] [7] The resin composition according to [6] above further comprises a polymerization initiator.

[0016] [8] A cured product, which is a cured product of the resin composition described in [6] or [7] above.

[0017] [9] A sheet comprising the resin composition and substrate described in [6] or [7] above.

[0018]

[10] According to the sheet described in [9] above, wherein, The aforementioned substrate is an organic substrate.

[0019]

[11] According to the sheet described in [9] above, wherein, The above-mentioned substrate is an inorganic substrate.

[0020]

[12] A laminate formed by further hot-pressing a substrate onto the bonding surface of the sheet described in any one of [9] to

[11] .

[0021]

[13] A printed circuit board made of any one of the sheets described in [9] to

[11] .

[0022]

[14] A printed circuit board made of the laminate described above

[12] .

[0023] Invention Effects According to the present invention, a maleimide resin capable of forming a cured product that sufficiently maintains low dielectric constant and low dielectric loss tangent while exhibiting high elastic modulus and high Tg, and possesses excellent toughness can be provided. The present invention also provides a resin composition, cured product, sheet, laminate, and printed circuit board using the above-described maleimide resin.

[0024] The maleimide resin of the present invention and the resin composition (adhesive composition) using the maleimide resin can simultaneously reduce the dielectric constant and dielectric loss tangent (hereinafter, both are sometimes collectively referred to as "dielectric properties"), especially exhibiting excellent low dielectric properties in the high-frequency band. Furthermore, the cured product (adhesive layer) obtained from the above resin composition not only has high elastic modulus and Tg but also excellent toughness. Therefore, the above resin composition is useful as an adhesive used in the manufacture of printed circuit boards (additional substrates, flexible printed circuit boards, etc.) and copper foil for printed circuit boards, and is also useful as an insulating film such as a rewiring layer, a semiconductor interlayer material, a coating agent, a resist ink, a conductive paste, etc. Detailed Implementation

[0025] The preferred embodiments of the present invention will now be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be implemented within its scope.

[0026] In this specification, the numerical range indicated by "~" represents the range encompassed by the values ​​before and after "~" as the minimum and maximum values, respectively. Within the numerical ranges described in stages in this specification, the upper or lower limit of a certain stage's numerical range can be arbitrarily combined with the upper or lower limits of other stages' numerical ranges. Within the numerical ranges described in this specification, the upper or lower limit of the numerical range can be replaced with the values ​​shown in the examples. "A or B" may include either A or B, or both. Unless otherwise specified, the materials exemplified in this specification can be used individually or in combination of two or more. When multiple substances belonging to each component exist in the composition, unless otherwise specified, the content of each component in the composition refers to the total amount of the multiple substances present in the composition. In this specification, "solid component" refers to the non-volatile component contained in the resin composition after removing volatile substances (water, solvents, etc.), and also includes components that are liquid, syrupy, or waxy at room temperature (around 25°C).

[0027] [Maleimide resin and resin composition] The maleimide resin of this embodiment is a maleimide resin obtained by reacting tetracarboxylic dianhydride (a1) (hereinafter also referred to as "(a1) component"), amine (a2) (hereinafter also referred to as "(a2) component"), and maleic anhydride (a3) ​​(hereinafter also referred to as "(a3) component"). Here, the aforementioned (a1) component contains tetracarboxylic dianhydride having a fluorene backbone, and the aforementioned (a2) component contains a dimerized diamine and an amine having a biphenyl backbone. The benzene backbone may have lower alkyl groups (e.g., methyl, ethyl, propyl, etc.) as substituents.

[0028] The resin composition of this embodiment contains the aforementioned maleimide resin (A) (hereinafter also referred to as "component (A)"). The resin composition of this embodiment may further contain a polymerization initiator (B) (hereinafter also referred to as "component (B)"). Furthermore, the resin composition of this embodiment may further contain an organic solvent (C) (hereinafter also referred to as "component (C)").

[0029] (Component A: Maleimide resin) Regarding component (A), it can be obtained by reacting components (a1), (a2), and (a3). Component (A) may have multiple maleimide groups within its molecule. Component (A) may be a bismaleimide resin.

[0030] (a1) The tetracarboxylic dianhydride of component (a1) comprises a tetracarboxylic dianhydride having a fluorene skeleton. From the viewpoint of low dielectric properties, high Tg, or low coefficient of linear expansion (CTE), component (a1) is preferably a tetracarboxylic dianhydride having a fluorene skeleton containing at least one of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.

[0031] (a1) The component may further include a tetracarboxylic dianhydride that does not have a fluorene skeleton. The tetracarboxylic dianhydride that does not have a fluorene skeleton may have a biphenyl skeleton or an aromatic ring other than biphenyl.

[0032] Examples of tetracarboxylic dianhydrides that do not possess a fluorene skeleton include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione, 4,4'-oxobisphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3, 3',4,4'-Biphenyltetracarboxylic anhydride, 2,3',3,4'-Biphenyltetracarboxylic anhydride, 3,3',4,4'-Benzophenonetetracarboxylic anhydride, 4,4'-(4,4'-Isopropylidenediphenoxy)diphthalic anhydride, 1,2,3,4-Butanetetracarboxylic anhydride, 1,2,3,4-Cyclobutanetetracarboxylic anhydride, 1,2,3,4-Cyclopentanetetracarboxylic anhydride, 1,2,3,4-Tetra-... Methyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, bis(1,3-dioxo-1,3-dihydroxyisobenzofuran-5-carboxylic acid)1,4-phenylene, 4,4'-(acetylene-1,2-diyl)diphthalic anhydride, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2- Dicarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic anhydride, 3,4'-oxobisphthalic anhydride, 3,4'-diphthalic anhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic anhydride, and 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic anhydride-5,5',6,6'-dianhydride. They can be used alone or in combination of two or more.

[0033] (a2) The components include a dimerized diamine (the first amine) and an amine with a biphenyl skeleton (the second amine).

[0034] For example, as described in Japanese Patent Application Publication No. 9-12712, dimer diamines are compounds derived from dimers of unsaturated fatty acids such as oleic acid, i.e., dimer acids. By using dimer diamines as component (a2), the dielectric properties of the cured product can be reduced. In this embodiment, known dimer diamines can be used without particular limitation. Dimer diamines are preferably, for example, compounds represented by the following general formula (1) and compounds represented by the following general formula (2).

[0035] In equations (1) and (2), m, n, p, and q represent integers of 1 or higher selected in the manner of m+n=6~17 and p+q=8~19, respectively. The bonds represented by dashed lines refer to carbon-carbon single bonds or carbon-carbon double bonds. Among them, when the bonds represented by dashed lines are carbon-carbon double bonds, equations (1) and (2) have the following structure: the structure obtained by subtracting 1 from the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond as shown in equations (1) and (2).

[0036] As a dimer, diamine can be represented by the above general formula (2) from the viewpoint of solubility in organic solvents, heat resistance, heat-resistant adhesion, low viscosity, etc., and in particular, it can be a compound represented by the following formula (3).

[0037] Commercially available products as dimerized diamines include, for example, PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Croda Japan KK). They can be used alone or in combination of two or more.

[0038] Examples of amines having a biphenyl skeleton include 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-2,2'-diethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-diethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetramethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetraethylbiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, and 4,4'-diamino-3,3'-dimethoxybiphenyl. An amine having a biphenyl skeleton can be a diamine having a biphenyl skeleton.

[0039] (a2) The component may further include a third amine other than a dimerized diamine and an amine with a biphenyl backbone. The third amine may be a diamine or a triamine, or it may be a diamine. By using an alicyclic diamine as the third amine, the dielectric constant can be further reduced. By using an aromatic diamine as the third amine, the elastic modulus, Tg, and CTE of the cured product can be improved.

[0040] When the third amine is a diamine, examples of such diamines include 1,3-diaminopropane, norbornene diamine, 4,4-methylenediphenylamine, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[3-fluoro-4-aminophenyl]fluorene, and 9,9-bis[4-(4-aminophenyl)fluorene. [-aminophenoxy]phenyl]fluorene, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornene, 4,4'-(hexafluoroisopropylidene)diphenylamine, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.02,6]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine) 4,4'-Methylenebis(2-methylcyclohexylamine), 1,1-bis(4-aminophenyl)cyclohexane, 2,7-diaminofluorene, 4,4'-ethylidene diphenylamine, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]methane, bis [4-(4-aminophenoxy)phenyl] ether, bis[4-(4-aminophenoxy)phenyl] ketone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, (4,4'-diamino)diphenyl ether, (3,3'-diamino)diphenyl ether, p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, bis[4-(3-aminophenoxy)phenyl] sulfone, and bis[4-(4-aminophenoxy)phenyl] sulfone. They can be used alone or in combination of two or more.

[0041] When the third amine is a triamine, examples of such triamines include tris(2-aminomethyl)amine, tris(2-aminoethyl)amine, tris(2-aminopropyl)amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, melamine, 3,4,4'-triaminodiphenyl ether, 1,2,4-triaminobenzene, 1,3,5-triaminobenzene, 1,2,3-triaminobenzene, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triaminopyrimidine, 1,3,5-tris(4-aminophenyl)benzene, and 1,3,5-tris(4-aminophenoxy)benzene. These can be used alone or in combination of two or more. From the viewpoint of the solubility of the synthesized component (A) in organic solvents, an aliphatic triamine is preferred. Furthermore, from the viewpoint of high Tg, tri(2-aminomethyl)amine or tri(2-aminoethyl)amine, which have fewer carbon atoms, are more preferred.

[0042] The third amine may include one or both of the aforementioned diamines and triamines. Furthermore, the third amine may include amines other than diamines and triamines.

[0043] In component (a2), the molar ratio of the second amine relative to the total amount of amine (moles of the second amine / (moles of the dimer diamine + moles of the second amine)) can be 70 mol% or less, or 50 mol% or less. If this ratio is 70 mol% or less, the dielectric properties of the cured product can be further reduced.

[0044] By using a dimerized diamine as the diamine, the dielectric properties of the cured product can be reduced. On the other hand, when only a dimerized diamine is used as the amine, the elastic modulus and Tg of the cured product decrease, while the CTE increases. In contrast, by using an amine with a biphenyl backbone in combination with a dimerized diamine, the dielectric properties of the cured product can be maintained while improving the elastic modulus, Tg, CTE, and toughness.

[0045] (A) Component can be manufactured by various known methods. For example, firstly, components (a1) and (a2) are subjected to an addition polymerization reaction typically for about 0.1 to 2 hours (preferably 0.1 to 1.0 hours) at a temperature of about 60 to 120°C (preferably 70 to 90°C). Next, the obtained addition polymer is subjected to an imidization reaction, i.e., a dehydration and ring-closure reaction, at a temperature of about 80 to 250°C (preferably 100 to 200°C) for about 0.5 to 30 hours (preferably 0.5 to 10 hours). Then, the substance that has undergone the dehydration and ring-closure reaction is subjected to a maleimidization reaction, i.e., a dehydration and ring-closure reaction, with component (a3) ​​at a temperature of about 60 to 250°C (preferably 80 to 200°C) for about 0.5 to 30 hours (preferably 0.5 to 10 hours), thereby obtaining the desired component (A).

[0046] In imidization or maleimidization reactions, various known reaction catalysts, dehydrating agents, and organic solvents (described later) can be used. Examples of reaction catalysts include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, methylpyridine, and isoquinoline, and organic acids such as methanesulfonic acid and p-toluenesulfonic acid monohydrate. These can be used alone or in combination of two or more. Examples of dehydrating agents include aliphatic anhydrides such as acetic anhydride and aromatic anhydrides such as benzoic anhydride. These can be used alone or in combination of two or more.

[0047] Component (A) can be purified using various known methods to improve its purity. For example, first, component (A) dissolved in an organic solvent and pure water are added to a separatory funnel. Then, the separatory funnel is shaken and allowed to stand. After the aqueous and organic layers separate, only the organic layer is recovered, thereby purifying component (A).

[0048] An example of the hypothetical structure of component (A) produced by the above method is shown in the following general formula (4). General formula (4) assumes that component (a2) is a diamine.

[0049] In general formula (4), X independently represents a tetravalent organic group, Y independently represents a divalent organic group, and a represents an integer greater than or equal to 1. At least one of the plurality of Y groups represents a divalent organic group derived from a dimerized diamine, and at least one of the plurality of Y groups represents a divalent organic group derived from an amine having the aforementioned biphenyl skeleton. Furthermore, at least one of the plurality of X groups represents a tetravalent organic group having a fluorene skeleton.

[0050] (A) The molecular weight of component A can be controlled by the molar number of component (a1) and component (a2). The smaller the molar number of component (a1) is compared to the molar number of component (a2), the greater the reduction in molecular weight. For the purpose of easily achieving the effects of the present invention, the molar number of component (a1) relative to 1 mole of component (a2), i.e., [molar number of component (a1)] / [molar number of component (a2)], can typically be in the range of about 0.30 to 0.98 (preferably 0.40 to 0.96, more preferably 0.50 to 0.94, and even more preferably 0.60 to 0.90).

[0051] The molecular weight of component (A), from the viewpoint of solubility in solvents and heat resistance, is preferably 3,000 to 40,000 in terms of weight-average molecular weight (Mw), and can be 4,000 to 30,000, 5,000 to 28,000, 7,000 to 27,000, or 8,000 to 26,500. There is a tendency that if the weight-average molecular weight is below 40,000, the solubility in organic solvents becomes good, and if it is above 3,000, the effect of improved heat resistance is sufficiently obtained. Mw can be determined by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene.

[0052] (A) The ingredient can be used alone or in combination of two or more.

[0053] (Component (B): Polymerization initiator) As component (B), various known components can be used without particular limitation, as long as they are polymerization initiators that can be used in the resin composition. Specifically, examples of component (B) include organic peroxides, imidazole compounds, phosphine compounds, and phosphonium salt compounds. They can be used alone or in combination of two or more. Among these, organic peroxides and imidazole compounds are particularly preferred because they possess excellent properties as polymerization initiators and are also superior from the viewpoint of low dielectric properties.

[0054] Examples of organic peroxides include methyl ethyl ketone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetone peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-hexylperoxy)cyclohexane, 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane, 1,1-bis(tert-butylperoxy)cyclododecane, n-butyl-4,4-bis(tert-butylperoxy)valerate, 2,2-bis(tert-butylperoxy)butane, and 1,1-bis( tert-Butylperoxy)-2-methylcyclohexane, tert-Butyl hydroperoxide, p-Menthane hydroperoxide, 1,1,3,3-Tetramethylbutyl hydroperoxide, tert-Hexyl hydroperoxide, dicumyl peroxide, 2,5-Dimethyl-2,5-bis(tert-Butylperoxy)hexane, α,α'-bis(tert-Butylperoxy)diisopropylbenzene, tert-Butylisopropylbenzene peroxide, di-tert-Butyl peroxide, 2,5-Dimethyl-2,5-bis(tert-Butylperoxy)hexyne-3, isobutyryl peroxide, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, cinnamic acid peroxide, m-Toluyl (m -Toluoyl) peroxide, benzoyl peroxide, diisopropylperoxydicarbonate, bis(4-tert-butylcyclohexyl)peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-sec-butylperoxydicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, di(4-tert-butylcyclohexyl)peroxydicarbonate, α,α'-bis(neodecanylperoxy)diisopropylbenzene, isopropylbenzene peroxyneodecanate, 1,1,3,3'-tetramethylbutylperoxyneodecanate, 1-cyclohexyl-1-methylethylperoxyneodecanate, tert-hexylperoxyneodecanate, tert-butylperoxyneodecanate Oxylated neodecanoate, tert-hexylperoxyneopentate, tert-butylperoxyneopentate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, tert-hexylperoxy-2-ethylhexanoate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyisobutyrate, tert-butylperoxymaleate, tert-butylperoxylaurate, tert-butylperoxy-3,5,5-trimethylhexanoate, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-Di(benzoylperoxy)hexane, tert-butylperoxyacetic acid ester, tert-hexylperoxybenzoate, tert-butylperoxym-toluylbenzoate, tert-butylperoxybenzoate, bis(tert-butylperoxy)isophthalate, tert-butylperoxyallyl monocarbonate, and 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone. These can be used alone or in combination of two or more. Among these organic peroxides, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and α,α'-bis(tert-butylperoxy)diisopropylbenzene are preferred.

[0055] Examples of imidazole compounds include 2-ethyl-4-methylimidazolium, 2-methylimidazolium, 2-ethylimidazolium, 2,4-dimethylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 1-vinyl-2-methylimidazolium, 1-propyl-2-methylimidazolium, 2-isopropylimidazolium, 1-cyanomethyl-2-methylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, and 1-cyanoethyl-2-phenylimidazolium. Among these, 1-cyanoethyl-2-phenylimidazolium and 2-ethyl-4-methylimidazolium have high solubility in the resin composition of this embodiment and are therefore preferred. They can be used alone or in combination of two or more.

[0056] Examples of phosphine compounds include primary phosphine, secondary phosphine, and tertiary phosphine. Examples of primary phosphine include alkylphosphine such as ethylphosphine and propylphosphine, and phenylphosphine. Examples of secondary phosphine include dialkylphosphine such as dimethylphosphine and diethylphosphine, diphenylphosphine, methylphenylphosphine, and ethylphenylphosphine. Examples of tertiary phosphine include trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, trialkylphosphine, tricyclohexylphosphine, triphenylphosphine, alkyldiphenylphosphine, dialkylphenylphosphine, tribenzylphosphine, trimethylstyrylphosphine, tri-p-styrylphosphine, tris(2,6-dimethoxyphenyl)phosphine, tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, and tri-2-cyanoethylphosphine. Tertiary phosphines are preferred. They can be used alone or in combination of two or more.

[0057] Examples of phosphonium salt compounds include those containing tetraphenylphosphonium salts, alkyltriphenylphosphonium salts, and tetraalkylphosphonium. Specifically, examples include tetraphenylphosphonium-thiocyanate, tetraphenylphosphonium-tetra-p-methylphenylborate, butyltriphenylphosphonium-thiocyanate, tetraphenylphosphonium-phthalic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, tetrabutylphosphonium-1,2-cyclohexyldicarboxylic acid, and tetrabutylphosphonium-lauric acid. These compounds can be used alone or in combination of two or more.

[0058] The content of component (B) is not particularly limited, but it can be 0.1 to 10.0 parts by mass, 0.2 to 5.0 parts by mass, 0.3 to 3.0 parts by mass, 0.3 to 2.0 parts by mass or 0.3 to 1.0 parts by mass relative to 100 parts by mass of component (A).

[0059] (C) Component: Organic solvent) As component (C), there are no particular limitations as long as it dissolves component (A). Examples of components (C) include aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, 1,2,4-trimethylbenzene, and anisole; alcohol solvents such as methanol, ethanol, isopropanol, butanol, pentanol, hexanol, propylene glycol, and phenol; ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanol, hexanol, cyclopentanol, cyclohexanol, isophorone, and acetophenone; cellosols such as methyl cellosol and ethyl cellosol; and methyl acetate and acetic acid. Ester solvents such as ethyl acetate, butyl acetate, methyl propionate, butyl formate, and γ-butyrolactone; glycol ether solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. One or more of these solvents can be used. Preferably, aromatic hydrocarbons such as toluene or mesitylene, which have high solubility in component (A), are used.

[0060] (C) There is no particular limitation on the amount of component used, but it is generally acceptable to use a non-volatile component of the resin composition in this embodiment that is in the range of about 20 to 65% by mass.

[0061] The resin composition of this embodiment is prepared according to a generally adopted method. Examples of preparation methods include melt mixing, powder mixing, and solution mixing. Furthermore, without impairing the effects of the present invention, other components besides those necessary for this embodiment, such as release agents, flame retardants, ion traps, antioxidants, adhesives, stress reducers, colorants, coupling agents, and inorganic fillers, can be incorporated. The resin composition of this embodiment may contain resins other than those in component (A), such as epoxy resins, (meth)acrylate compounds, vinyl compounds, benzoxazine compounds, and maleimide compounds other than those in component (A).

[0062] (Mold release agent) Regarding mold release agents, they are added to improve the release properties from the mold. Examples of mold release agents include carnauba wax, rice bran wax, candelilla wax, polyethylene, oxidized polyethylene, polypropylene, linalic acid, esters of linalic acid with saturated alcohols, 2-(2-hydroxyethylamino)ethanol, ethylene glycol, glycerin, etc., i.e., linalool, stearic acid, stearate esters, stearamide, and all other known mold release agents. They can be used alone or in combination of two or more.

[0063] (Flame retardant) Regarding flame retardants, all known flame retardants can be used to impart flame retardancy, and there are no particular limitations. Examples of flame retardants include phosphazene compounds, silicon compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, and molybdenum oxide. They can be used alone or in combination of two or more.

[0064] (ion scavenger) Ion scavengers are added to capture ionic impurities contained in liquid resin compositions to prevent thermal and hygroscopic degradation. All known ion scavengers can be used without particular limitation. Examples of ion scavengers include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides. They can be used alone or in combination of two or more.

[0065] (Inorganic packing) Regarding inorganic fillers, various known inorganic fillers can be used without particular limitation, as long as they are suitable for use in resin compositions. Examples of inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, boron nitride, silicon dioxide, graphite powder, and boehmite. Among these, silicon dioxide is particularly preferred due to its excellent low dielectric loss tangent. One type of inorganic filler can be used alone or in combination of two or more.

[0066] The average particle size of the inorganic filler can be 50 nm or more, 100 nm or more, or 200 nm or more, or it can be less than 10 μm, 5.0 μm or less, 3.0 μm or less, or 1.0 μm or less. The average particle size of the inorganic filler is preferably 100 nm to 10 μm or 50 nm to 5.0 μm, more preferably 100 nm to 3.0 μm, and even more preferably 200 nm to 1.0 μm. If the average particle size of the inorganic filler is within the above range, the surface roughness of the sheet can be reduced, thereby improving adhesion to substrates such as polyimide films and copper foils.

[0067] The average particle size of the aforementioned inorganic filler is taken as the median particle size (d50) that represents 50% of the total particle size distribution. This average particle size can be measured using a particle size distribution measuring device based on laser diffraction scattering.

[0068] The inorganic filler is preferably surface-treated, preferably a surface-treated material based on a coupling agent, and more preferably a surface-treated material based on a silane coupling agent. By surface-treating the above-mentioned inorganic filler, not only can the dispersibility of the inorganic filler in organic solvents be improved, but the surface roughness of the sheet surface is further reduced, thereby improving the adhesion to substrates such as polyimide films and copper foils.

[0069] Examples of coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of the aforementioned silane coupling agents include methacrylsilane, acryloylsilane, aminosilane, phenylaminosilane, imidazolesilane, phenylsilane, vinylsilane, and epoxysilane. They can be used alone or in combination of two or more.

[0070] When the resin composition contains inorganic fillers, the content can be 5–75% by mass, 5–50% by mass, 5–35% by mass, or 10–30% by mass, based on the total amount of solid components (non-volatile components) of the resin composition (100% by mass). If the content of inorganic fillers is 75% by mass or less, there is a tendency to suppress the reduction of adhesion; if the content of inorganic fillers is 5% by mass or more, there is a tendency to fully obtain the effect of reducing dielectric loss tangent and improving heat resistance.

[0071] [cured material] The cured product of this embodiment is obtained by curing the resin composition of this embodiment. Specifically, it can be obtained by heat-treating the composition at about 150 to 250°C for about 10 minutes to 3 hours.

[0072] The shape of the cured material in this embodiment is not particularly limited, but when used for bonding substrates, it can be made into a sheet with a film thickness of about 1 to 200 μm (preferably about 3 to 100 μm), and the film thickness can be adjusted appropriately according to the application.

[0073] [Sheet] The sheet of this embodiment comprises the resin composition and substrate of this embodiment. The sheet of this embodiment is obtained, for example, by coating the resin composition of this embodiment onto a substrate (sheet substrate) and drying it. Examples of such substrates include organic substrates such as polyimide, polyimide-silica mixtures, polyamide, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate resin (PMMA), polystyrene resin (PSt), polycarbonate resin (PC), acrylonitrile-butadiene-styrene resin (ABS), polyethylene terephthalate, phenol, phthalic acid, hydroxynaphthalic acid, and aromatic polyester resins obtained from p-hydroxybenzoic acid (so-called liquid crystal polymers: manufactured by KURARAY CO., LTD., "Vexter", etc.). From the viewpoint of heat resistance and dimensional stability, polyimide films, especially polyimide-silica mixture films, are preferred. Furthermore, the aforementioned substrates can be made of metals such as glass, iron, aluminum, 42 alloy, and copper, or inorganic substrates such as ITO, silicon, and silicon carbide. The thickness of the aforementioned substrates can be appropriately set according to the application.

[0074] [Layered Body] The laminate of this embodiment is obtained by further hot-pressing a substrate onto the bonding surface of the aforementioned sheet. As this substrate, organic substrates such as polyimide, polyimide-silica mixtures, polyamide, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polystyrene resin (PSt), polycarbonate resin (PC), acrylonitrile-butadiene-styrene resin (ABS), polyethylene terephthalate, phenol, phthalic acid, hydroxynaphthalic acid, and aromatic polyester resins (liquid crystal polymers) obtained from p-hydroxybenzoic acid can be used. Furthermore, inorganic substrates such as glass, iron, aluminum, alloy 42, copper, ITO, silicon, and silicon carbide can also be used. The thickness of the substrate can be appropriately set according to the application. Furthermore, the laminate can be further subjected to heat treatment.

[0075] [Printed substrates and printed circuit boards] The printed circuit board of this embodiment uses the aforementioned sheet or the aforementioned laminate. The printed circuit board of this embodiment is obtained, for example, by further bonding the adhesive surface of the aforementioned sheet to the inorganic substrate surface of the aforementioned laminate. Preferably, a polyimide film is used as the organic substrate and a metal foil (especially copper foil) is used as the inorganic substrate. Furthermore, a circuit is formed by soft etching the metal surface of the printed circuit board, and the aforementioned sheet is further bonded thereon and hot-pressed, thereby obtaining a printed circuit board.

[0076] Example The present invention will now be specifically described through examples and comparative examples, but the present invention is not limited thereto. Furthermore, in each example, unless otherwise specified, parts and percentages refer to quality standards.

[0077] Synthesis of maleimide resin To synthesize maleimide resin, the following components (a1) to (a3), acid catalyst and solvent were prepared.

[0078] ((a1) ingredient) BPAF: 9,9-bis(3,4-dicarboxyphenyl)fluorenic dianhydride (manufactured by JFE Chemical Corporation, product name "BPAF") PMDA: Pyromellitic dianhydride (prepared by DAICL CORPORATION) BISDA: 4,4'-(4,4'-isopropylidene diphenoxy)phthalic anhydride (manufactured by SABIC, product name "BISDA-1000") s-BPDA: 3,3',4,4'-Biphenyltetracarboxylic acid dianhydride (manufactured by JFE Chemical Corporation, product name "BPDA") a-BPDA: 2,3',3,4'-Biphenyltetracarboxylic acid dianhydride (manufactured by JFE Chemical Corporation, product name "a-BPDA") ODPA: 4,4'-O-diphthalic anhydride (Manac Inc., product name "ODPA") (a2) component) DDA: Dimeric diamine (manufactured by CRODA JAPAN KK, product name "PRIAMINE1075") mTBHG: 4,4'-Diamino-2,2'-Dimethylbiphenyl (manufactured by Wakayama Seika Co., Ltd., product name "m-TB-HG") NBDA: Norbornenediamine (manufactured by Mitsui Chemicals Fine Chemicals Inc.) TAEA: Tris(2-aminoethyl)amine (manufactured by Tokyo Chemical Industry Co., Ltd.) (a3) component) Maleic anhydride (manufactured by FUJI SANGYO CO., LTD.) (Acid catalyst) Mesylate aqueous solution (manufactured by BASF, product name "Lutropur MSA") (solvent) 1,2,4-Trimethylbenzene (manufactured by TOYOBO CO., LTD., an aromatic high-boiling-point solvent) Solmix A-11 (made by Nippon Alcohol Co., Ltd., an alcohol-based solvent) Toluene (manufactured by Yamaichi Chemical Industries Co., Ltd.) γ-Butyrolactone (manufactured by FUJIFILM Wako Pure Chemical Corporation) (Synthesis example 1) 34.38 parts by weight of 9,9-bis(3,4-dicarboxyphenyl)fluorenic dianhydride (BPAF), 135.84 parts by weight of 1,2,4-trimethylbenzene, 1.922 parts by weight of Solmix A-11, and 31.00 parts by weight of γ-butyrolactone were added to a 0.3 L flask equipped with a cooler, nitrogen inlet tube, thermocouple, and stirrer. After addition, the temperature was raised to 80 °C and maintained for 0.5 hours. 26.85 parts by weight of dimerized diamine (DDA) were added dropwise, followed by 10.62 parts by weight of 4,4'-diamino-2,2'-dimethylbiphenyl (mTBHG). After the addition, 1.92 parts by weight of an aqueous solution of methanesulfonic acid was added, and the temperature was raised to 160 °C. After heating, 40.00 parts by weight of toluene were added, and a dehydration and ring-closure reaction was carried out at 160°C for 1 hour to remove water and alcohol from the reaction solution, yielding the intermediate polyimide resin. Next, the polyimide resin was cooled to 130°C, and 7.36 parts by weight of maleic anhydride were added. The temperature was then raised to 160°C, and a dehydration and ring-closure reaction was carried out at 160°C for 4 hours to remove water from the reaction solution, yielding the maleimide resin.

[0079] Maleimide resin was added to a separatory funnel, along with 500 parts by weight of pure water. The funnel was shaken to mix the mixture, and then allowed to stand. After standing, the aqueous and organic layers separated, and only the organic layer was recovered. The recovered organic layer was placed into a 1L glass container equipped with a cooler, nitrogen inlet pipe, thermocouple, stirrer, and vacuum pump. The container was heated to 88–93°C to remove the water, and then heated to 100°C. The solvent was partially removed for 0.5 hours under a pressure reduction of 0.1 MPa from atmospheric pressure, yielding a solution of maleimide resin (A-1) of component (A).

[0080] (Synthesis example 2) The formulation of each component was modified as shown in Table 1 to obtain maleimide resin before purification. 500 g of isopropanol (manufactured by FUJIFILM Wako Pure Chemical Corporation) was added to a 1 L glass container equipped with a stirrer. The obtained maleimide resin was then added while stirring at 300 rpm, and further stirred for 30 minutes to allow for reprecipitation. The reprecipitated maleimide resin was recovered. The recovered maleimide resin and 500 g of isopropanol were added to a 1 L glass container and stirred at 300 rpm for 30 minutes. After stirring, the maleimide resin was recovered and dried at 70°C for 12 hours to obtain maleimide resin of component (A) (A-2).

[0081] (Synthesis Example 3 to Synthesis Example 9) The proportions of each component were changed as shown in Table 1. Otherwise, solutions of maleimide resins (A-3) to (A-9) were obtained in the same manner as in Synthesis Example 1.

[0082] (Synthesis Example 10, Synthesis Example 12 to Synthesis Example 14) The proportions of each component were changed as shown in Table 2. Otherwise, solutions of maleimide resins (A-10), (A-12) to (A-14) were obtained in the same manner as in Synthesis Example 1.

[0083] (Synthesis Example 11) By changing the proportions of each component as shown in Table 2, maleimide resin (A-11) was obtained in the same manner as in Synthesis Example 2.

[0084] (Synthesis Example 15 to Synthesis Example 19) The proportions of each component were changed as shown in Table 3. Otherwise, solutions of maleimide resins (A-15) to (A-19) were obtained in the same manner as in Synthesis Example 1.

[0085] (Non-volatile components) Using a precision balance, 0.75 g ± 0.25 g of solutions of maleimide resins (A-1), (A-3) to (A-10), (A-12) to (A-14), and (A-15) to (A-19), as well as powders of maleimide resins (A-2) and (A-11), were weighed into a metal petri dish. The solutions were then dried in a hot air dryer at 150°C for 0.5 hours. The non-volatile component (NV) was calculated using the following formula.

[0086] NV (mass%) = {(W3-W1) / W2} × 100 W1: Mass of the empty metal petri dish (g) W2: Mass (g) of maleimide resin solution or powder before drying. W3: Mass (g) of dried metal petri dish + maleimide resin (weight-average molecular weight) The weight-average molecular weight (Mw) of the maleimide resin was determined by GPC (gel permeation chromatography). 50 μL of sample was injected into columns heated to 30°C (one GL-R420 (manufactured by Hitachi High-Tech Corporation), one GL-R430 (manufactured by Hitachi High-Tech Corporation), and one GL-R440 (manufactured by Hitachi High-Tech Corporation). The sample was prepared by dissolving the maleimide resin in tetrahydrofuran (THF) to a concentration of 3% by mass. The determination was performed using THF as the developing solvent at a flow rate of 1.6 mL / min. An L-3350 RI detector (manufactured by Hitachi, Ltd.) was used as the detector, and Mw was calculated based on the dissolution time using a molecular weight / dissolution time curve prepared using standard polystyrene (manufactured by TOSOHCORPORATION). The maleimide resin (A-11) of Synthetic Example 11 was insoluble in THF, therefore Mw could not be determined.

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] [Examples 1-14 and Comparative Examples 1-5] (Preparation of the resin composition) Maleimide resin compositions of Examples 1 to 9 were prepared by mixing the components shown in Table 4 with the compositions shown in Table 5 with the compositions shown in Table 6 with the compositions shown in Table 7. The mixing amounts of components (A) shown in Tables 4 to 6 represent the mixing amounts (parts by mass) including solvent. Furthermore, the maleimide resin composition of Comparative Example 2, which used maleimide resin (A-11), was insoluble in the solvent and therefore could not be evaluated.

[0091] (A) Composition: Maleimide resin The maleimide resins (A-1) to (A-19) prepared in Synthesis Examples 1 to 19 (B) Component: Polymerization initiator (B-1) DCP (manufactured by NIPPON OIL CORPORATION, product name "Parkmill D", dicumyl peroxide) (C) Ingredients: Organic solvents (C-1) Toluene (manufactured by Yamaichi Chemical Industries Co., Ltd.) (C-2)DMF (N,N-dimethylformamide) (Preparation of cured sheets) Using an applicator, the aforementioned maleimide resin composition was coated onto a Cu foil (manufactured by MITSUI MINING & SMELTING CO.,LTD., product name "3EC-M2S-VLP") to achieve a thickness of 100 μm after drying. The foil was then dried at 130°C for 30 minutes using a dryer. Next, it was cured at 200°C for 1 hour using a nitrogen dryer. After curing, the foil was cooled to room temperature, and the copper foil was removed by etching with an ammonium persulfate aqueous solution. The cured sheet was then dried at 110°C for 30 minutes.

[0092] [Determination of Elastic Modulus and Tg] Test specimens with a sample size of 20mm × 10mm were prepared using cured sheets. The elastic modulus and Tg (tanδ peak value) at 20℃ were measured using a dynamic viscoelasticity measuring device (manufactured by SI-International, Ltd., product name "DMS6100") at a frequency of 1Hz, a measurement temperature of -40℃ to 220℃, and a heating rate of 10℃ / min.

[0093] [Coefficient of linear expansion] Test specimens with dimensions of 30 mm × 4 mm were fabricated from cured sheets. Using these specimens, the coefficient of linear expansion (CTE) was determined using a thermomechanical analysis apparatus (TMA / SS7100, manufactured by Hitachi High-Tech Science Corporation). The measurement mode was tensile, the load was 50 mN, the atmosphere was atmospheric, and the heating rate was 5 °C / min. The results of the second round of measurements from -20 to 40 °C were used as the CTE.

[0094] [5% weight loss temperature] 6.0–10.0 mg of cured sheet material was weighed into an open sample container (manufactured by Seiko Instruments Inc., product name "P / NSSC000E030"), and the temperature was measured under the conditions of nitrogen flow rate of 300 mL / min and heating rate of 10 °C / min. The 5% weight loss temperature (T) was determined. d5 The measuring apparatus used was a TG / DTA7200 (manufactured by Hitachi High-TechScience Corporation).

[0095] [Evaluation of dielectric properties] Test pieces with a sample size of 50 mm × 100 mm were fabricated using cured sheets. Using these test pieces, the relative permittivity (Dk) and dielectric loss tangent (Df) at 10 GHz were measured using a network analyzer (KEYSIGHT Technologies, product name "P5003A") and a split cylindrical resonator (KEYSIGHT Technologies). Based on the measurement results, evaluations were performed according to the following criteria. A result of A or B indicates that the dielectric properties are sufficiently low.

[0096] <Dk Judgment Criteria> A: Less than 2.5 B: 2.5 or higher and less than 2.8 C: 2.8 and above <Df Judgment Criteria> A: Less than 0.0030 B: 0.0030 or higher and less than 0.0050 C: Above 0.0050 [Evaluation of resilience] Using an applicator, the aforementioned maleimide resin composition was coated onto Filmbyna (registered trademark) (PET film, manufactured by FUJIMORI KOGYO CO.,LTD., product name "NS14", thickness 75 μm) to achieve a thickness of 50 μm after drying. The coated film was then dried at 130°C for 30 minutes to obtain an adhesive sheet. Test pieces with a sample size of 10 mm × 50 mm were prepared using the adhesive sheet, and the minimum diameter at which the adhesive sheet broke was determined using a mandrel testing machine. The results were evaluated according to the following criteria.

[0097] <Criteria for Determining Toughness> A: Below 10.0mm B: 10.1mm or more and 15.0mm or less C: 15.1mm and above [Table 4]

[0098] [Table 5]

[0099] [Table 6]

[0100] As clearly shown in Tables 4 and 5, the resin compositions using the maleimide resin of the embodiments exhibit excellent cured properties, including low dielectric properties (low Dk and low Df), high elastic modulus, high Tg, low CTE, and high toughness. Therefore, by using the maleimide resin of the present invention, it is expected that the properties of sealing materials for laminates such as printed circuit boards and electronic components such as semiconductors can be significantly improved.

Claims

1. A maleimide resin, which is a maleimide resin prepared by reacting tetracarboxylic dianhydride (a1), an amine (a2), and maleic anhydride (a3), wherein, The tetracarboxylic dianhydride (a1) comprises a tetracarboxylic dianhydride having a fluorene skeleton. The amine (a2) comprises dimer diamine and amines having a biphenyl backbone.

2. The maleimide resin according to claim 1, wherein, The tetracarboxylic dianhydride with a fluorene skeleton contains at least one of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.

3. The maleimide resin according to claim 1, wherein, The amine having a biphenyl skeleton contains at least one selected from 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-2,2'-diethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diamino-3,3'-diethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetramethylbiphenyl, 4,4'-diamino-3,3',5,5'-tetraethylbiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-diamino-2,2'-dimethoxybiphenyl, and 4,4'-diamino-3,3'-dimethoxybiphenyl.

4. The maleimide resin according to claim 1, wherein, The dimer diamine contains at least one of the compounds represented by general formula (1) and general formula (2). In equations (1) and (2), m, n, p and q represent integers of 1 or more selected in the manner of m+n=6~17 and p+q=8~19 respectively. The bond represented by the dashed line refers to a carbon-carbon single bond or a carbon-carbon double bond. In the case where the bond represented by the dashed line is a carbon-carbon double bond, equations (1) and (2) have the following structure: the structure obtained by subtracting 1 from the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond as shown in equations (1) and (2).

5. The maleimide resin according to claim 1, wherein, The weight-average molecular weight is 3,000 to 40,000.

6. A resin composition comprising the maleimide resin according to any one of claims 1 to 5.

7. The resin composition according to claim 6, further comprising a polymerization initiator.

8. A cured product, which is a cured product of the resin composition of claim 6.

9. A sheet comprising the resin composition and substrate of claim 6.

10. The sheet according to claim 9, wherein, The substrate is an organic substrate.

11. The sheet according to claim 9, wherein, The substrate is an inorganic substrate.

12. A laminate formed by further hot-pressing a substrate onto the bonding surface of the sheet of claim 9.

13. A printed circuit board made using the sheet of claim 9.

14. A printed circuit board comprising the laminate of claim 12.

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