Thermosetting resin composition, resin sheet, laminate, and printed wiring board

Abstract

The present disclosure provides a thermosetting resin composition which, when the thermosetting resin composition and a semi-cured product thereof are heated, exhibits a property of first maintaining a low melt viscosity state and then rapidly becoming curable, which improves the storage stability of the thermosetting resin composition and the semi-cured product thereof, and reduces an increase in a linear expansion coefficient and suppresses a decrease in a glass transition temperature of a cured product, which is often associated with heating. The thermosetting resin composition contains a radically polymerizable unsaturated compound and an organic radical compound.

Description

Technical Field

[0001] This disclosure generally relates to thermosetting resin compositions, resin sheets, laminates, and printed circuit boards. More specifically, this disclosure relates to thermosetting resin compositions containing free radical polymerizable unsaturated compounds, resin sheets made from the thermosetting resin compositions, laminates including insulating layers made from the thermosetting resin compositions, and printed circuit boards including insulating layers made from the thermosetting resin compositions. Background Technology

[0002] Patent Document 1 discloses a thermosetting adhesive composition for forming a thermosetting adhesive film for manufacturing printed circuit boards. This thermosetting adhesive composition contains, in a predetermined ratio: a vinyl compound having a polyphenylene ether backbone; a maleimide resin; and a thermoplastic elastomer comprising a polyolefin backbone as a major component, and is a copolymer of polyolefin blocks and polystyrene blocks. This thermosetting adhesive composition has a tensile stress of 0.1-2.9 MPa at 100% elongation and an elongation of more than 100% when the thermosetting adhesive composition is cut.

[0003] Citation List

[0004] Patent documents

[0005] Patent Document 1: WO 2016 / 117554 A1 Invention Overview

[0007] One object of this disclosure is to provide a thermosetting resin composition that, when heated, exhibits the property of initially maintaining a low melt viscosity and then rapidly becoming curable. This improves the storage stability of the thermosetting resin composition and its semi-cured product, reduces the increase in the coefficient of linear expansion, and suppresses the decrease in the glass transition temperature of the cured product, which is typically associated with heating. Another object of this disclosure is to provide a resin sheet made from such a thermosetting resin composition. A further object of this disclosure is to provide a laminate comprising an insulating layer made from the thermosetting resin composition. Yet another object of this disclosure is to provide a printed circuit board comprising an insulating layer made from the thermosetting resin composition.

[0008] According to one aspect of this disclosure, the thermosetting resin composition comprises: a free radical polymerizable unsaturated compound; and an organic free radical compound.

[0009] According to another aspect of this disclosure, the resin sheet comprises a dried or semi-cured product of the above-described thermosetting resin composition.

[0010] The laminate according to another aspect of this disclosure includes: an insulating layer and a metal foil sheet. The insulating layer contains a cured product of the above-described thermosetting resin composition.

[0011] A printed circuit board according to another aspect of this disclosure includes an insulating layer and conductor lines. The insulating layer contains a cured product of the above-described thermosetting resin composition. Brief description of the attached diagram

[0013] Figure 1 A is a schematic cross-sectional view illustrating a resin sheet according to an exemplary embodiment of the present disclosure;

[0014] Figure 1 B is an illustrative representation of the use of... Figure 1 A cross-sectional view of an exemplary printed circuit board formed from a resin sheet;

[0015] Figure 2 A and 2B are schematic cross-sectional views illustrating exemplary resin-containing metal foil sheets according to exemplary embodiments of the present disclosure.

[0016] Figure 3 A, 3B, 3C, and 3D are schematic cross-sectional views illustrating exemplary metal-coated laminates according to exemplary embodiments of the present disclosure; and

[0017] Figure 4 A, 4B, 4C, and 4D are schematic cross-sectional views illustrating exemplary printed circuit boards according to exemplary embodiments of the present disclosure.

[0018] Implementation Plan Description

[0019] First, it will be explained how the inventors obtained the basic concept of this disclosure.

[0020] In thermosetting resin compositions containing free radical polymerizable compounds (such as vinyl compounds having a polystyrene backbone) as disclosed in Patent Document 1, the thermosetting resin composition will rapidly cure before its viscosity becomes sufficiently low if the dried or semi-cured product of such a thermosetting resin composition is heated. Therefore, if an insulating layer is formed from such a thermosetting resin composition or its dried or semi-cured product, for example, to overlap with conductor lines, it may be difficult to adequately fill the gaps between portions of the conductor lines with the insulating layer. Furthermore, the curing reaction may occur during the storage of the thermosetting resin composition or its dried or semi-cured product.

[0021] However, if common polymerization inhibitors such as phenolic compounds are used to inhibit the polymerization reaction of thermosetting resin compositions or their dried or semi-cured products, the linear expansion coefficient of the cured product tends to increase and its glass transition temperature tends to decrease, which usually leads to the deterioration of the thermal properties of the cured product.

[0022] Therefore, in order to easily maintain a low viscosity state when heating thermosetting resin compositions or their dried or semi-cured products, improve their storage stability, reduce the increase in the coefficient of linear expansion of the cured products, and suppress the decrease in their glass transition temperature, which is generally observed when heating thermosetting resin compositions or their dried or semi-cured products, the inventors have conducted in-depth and meticulous research and development, thereby obtaining the basic concept of this disclosure.

[0023] An exemplary implementation of this disclosure will now be described.

[0024] A thermosetting resin composition according to an exemplary embodiment (hereinafter referred to as "Composition (X)") contains a free radical polymerizable unsaturated compound and an organic free radical compound. This is beneficial for Composition (X), the dried product of Composition (X), and the semi-cured product of Composition (X) to maintain a low viscosity upon heating. Additionally, this is beneficial for improving the storage stability of Composition (X), the dried product of Composition (X), and the semi-cured product of Composition (X). Furthermore, this reduces the likelihood of an increase in the coefficient of linear expansion of the cured product or a decrease in its glass transition temperature, as typically observed when heating Composition (X), the dried product of Composition (X), or the semi-cured product of Composition (X). Furthermore, this improves the flame retardancy of the cured product of Composition (X).

[0025] The inventors hypothesize that the mechanism contributing to these advantages of this embodiment is as follows:

[0026] When a free radical reactive substance is generated from a free radical polymerizable unsaturated compound, the free radical polymerization reaction proceeds in a chain reaction, thereby polymerizing the free radical polymerizable unsaturated compound. Common polymerization inhibitors, such as phenolic compounds, react with the free radical reactive substance to stop the free radical polymerization reaction, thus allowing the composition (X), its dried product, and its semi-cured product to maintain a low viscosity even under heating, and improving the storage stability of the composition (X), its dried product, and its semi-cured product. Nevertheless, the reaction product between the free radical reactive substance and the phenolic compound has such high stability that it significantly inhibits the polymerization reaction of the free radical polymerizable unsaturated compound. Therefore, polymerization inhibitors typically reduce the crosslinking density in the cured product, which generally tends to increase the linear expansion coefficient and lower the glass transition temperature of the cured product.

[0027] In contrast, according to this embodiment, when a free radical active substance is generated in the composition (X), its dried product, or its semi-cured product, the free radical active substance and the organic free radical compound react with each other, thereby generating a stable reaction product. Therefore, the composition (X), its dried product, and its semi-cured product can easily maintain a low viscosity even when heated. Furthermore, this also improves the storage stability of the composition (X), its dried product, and its semi-cured product. Moreover, when the reaction product between the free radical active substance and the organic free radical compound is further heated, the reaction product decomposes, typically regenerating the free radical active substance. It can be seen that when a free radical active substance is generated, the curing reaction tends to proceed rapidly. Therefore, the inventors speculate that this should be beneficial for increasing the crosslinking density of the cured product, which would reduce the likelihood of an increase in the linear expansion coefficient and a decrease in its glass transition temperature, and would also improve the flame retardancy of the cured product.

[0028] Next, the components that composition (X) may contain will be described.

[0029] As a compound (A) having a free radical polymerizable unsaturated bond (hereinafter referred to as "compound (A)"), any compound can be used without limitation, as long as it can be polymerized by a free radical polymerization reaction. Compound (A) may have, for example, an olefinic unsaturated bond, and more specifically, includes at least one group selected from the group consisting of: vinyl, allyl, methacrylate, styrene, meth(acrylate), and maleimide. The selection of the components contained in compound (A) allows control over the physical properties of composition (X), its semi-cured product, and its cured product. For example, if compound (A) contains a monofunctional compound having a single polymerizable unsaturated group, this monofunctional compound can reduce the melt viscosity of composition (X) and improve its formability. On the other hand, if compound (A) contains a polyfunctional compound having multiple polymerizable unsaturated groups, this polyfunctional compound can increase the crosslinking density of the cured product. Therefore, polyfunctional compounds contribute to improving the toughness of the cured product, its glass transition temperature and heat resistance, and reducing the coefficient of linear expansion.

[0030] The components that compound (A) may contain will be described in more detail below.

[0031] Compound (A) suitably contains a copolymer (A1) having structural units derived from monoolefins (hereinafter referred to as "monoolefin units") and structural units derived from dienes (hereinafter referred to as "diene units"). Such copolymer (A1) will be referred to as "copolymer (A1)" below.

[0032] Copolymers (A1) generally have film-forming ability, and therefore tend to improve formability when forming resin films by molding composition (X) into sheet form. This is because copolymers (A1) have a low dielectric constant, which tends to reduce the dielectric constant of the cured product. The diene unit is a polymerizable unsaturated group, which tends to reduce the linear expansion coefficient of the cured product. It also tends to improve the heat resistance of the cured product.

[0033] The monoolefin unit of the copolymer (A1) may include only one type of structural unit or two or more types of structural units. The monoolefin unit suitably includes one or more structural units selected from the group consisting of: structural units derived from ethylene (hereinafter referred to as "ethylene units"); structural units derived from propylene (hereinafter referred to as "propylene units"); structural units derived from butene (hereinafter referred to as "butene units"); structural units derived from α-olefins (hereinafter referred to as "α-olefin units"); structural units derived from hydrogenated butadiene (hereinafter referred to as "hydrogenated butadiene units"); and structural units derived from hydrogenated isoprene (hereinafter referred to as "hydrogenated isoprene units"). Note that the structural units included in the monoolefin unit are not limited to this group. For example, the monoolefin unit may include both ethylene and propylene units. That is, the copolymer (A1) may include ethylene-propylene-diene copolymers. Ethylene-propylene-diene copolymers are also commonly referred to as "EPDM (ethylene-propylene-diene terpolymer) rubber".

[0034] Diene units may include one or more structural units selected from the group consisting of: structural units derived from 5-ethylidene-2-norbornene (hereinafter referred to as "5-ethylidene-2-norbornene units"); structural units derived from dicyclopentadiene (hereinafter referred to as "dicyclopentadiene units"); structural units derived from 1,4-hexadiene (hereinafter referred to as "1,4-hexadiene units"); structural units derived from butadiene (hereinafter referred to as "butadiene units"); and structural units derived from isoprene (hereinafter referred to as "isoprene units"). The structural units included in a diene unit are not limited to this group. A diene unit suitably includes 5-ethylidene-2-norbornene units.

[0035] The copolymer (A1) suitably comprises ethylene units, propylene units, and 5-ethylidene-2-norbornene units. That is, the molecules in the copolymer (A1) suitably have a structure represented by, for example, the following formula (1), where n, m, and l are natural numbers, each representing the number of structural units in formula (1). Therefore, formula (1) is a compositional formula representing the ratio of structural units. Specifically, formula (1) indicates that the copolymer (A1) comprises n moles of ethylene units, m moles of propylene units, and 1 mole of diene unit. The 5-ethylidene-2-norbornene unit, as a diene unit, helps to accelerate the curing reaction of the composition (X), thereby shortening the time required for the composition (X) to cure.

[0036]

[0037] The mass ratio of diene units to the total copolymer (A1) is suitably equal to or greater than 3%. This helps to improve the heat resistance of the cured product. The ratio of diene units is more preferably in the range of 3% to 15%.

[0038] The mass ratio of ethylene units to the whole copolymer (A1) is suitably equal to or greater than 50%. This is advantageous for shaping the composition (X) into sheets. The ratio of ethylene units is more preferably in the range of 50% to 85%.

[0039] The Mooney viscosity (ML(1+4)) of the copolymer (A1) as defined in K6300-1:2013 is suitably 10 or higher at 100°C. This also allows for easy molding of the composition (X) into sheets, and results in molded products with reduced viscosity obtained by molding the composition into sheets. The Mooney viscosity (ML(1+4)) of the copolymer (A1) as defined in K6300-1:2013 is more preferably equal to or less than 80 at 125°C. Setting the Mooney viscosity to below 80 prevents the melt viscosity of the copolymer (A1) from becoming too high and improves the moldability of the cured product.

[0040] Note that the Mooney viscosity of the copolymer (A1) increases with increasing molecular weight. Therefore, the Mooney viscosity can be adjusted by at least one means selected from, for example, the group consisting of: adjusting the molecular weight of the molecules contained in the copolymer (A1); adding molecules with different molecular weights to the copolymer (A1) and adjusting their mixing ratio; and adjusting the molecules contained in the copolymer (A1) to have a branched structure.

[0041] Additionally, compound (A) suitably contains an end-group modified polyphenylene ether compound (A2) (hereinafter also referred to as "compound (A2)"). In this case, since compound (A2) typically possesses excellent dielectric properties, the dielectric constant and dielectric loss tangent of the cured product can be reduced. Furthermore, since compound (A2) is a flame-retardant material, excellent flame retardancy can be easily achieved.

[0042] Compound (A2) is a polyphenylene ether that has been end-modified with substituents having carbon-carbon unsaturated double bonds. That is, compound (A2) has, for example, a polyphenylene ether chain and substituents having carbon-carbon unsaturated double bonds bonded to the end groups of the polyphenylene ether chain.

[0043] Substituents having carbon-carbon unsaturated double bonds can be, for example, substituents represented by the following formula (2):

[0044]

[0045] Where n is a number in the range of 0 to 10, Z is an arylene group, and R1 to R3 each independently represent a hydrogen atom or an alkyl group. In equation (2), if n is zero, then Z is directly bonded to the polyphenylene ether chain.

[0046] The arylene group can be, for example, a monocyclic aryl group such as phenylene, or a polycyclic aryl group such as naphthylene. At least one hydrogen atom bonded to the aromatic ring of the arylene group can be substituted by a functional group such as alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. The arylene group is not limited to this group.

[0047] Alkyl groups are suitably alkyl groups having 1 to 18 carbon atoms, and more preferably alkyl groups having 1 to 10 carbon atoms. Specifically, alkyl groups can be, for example, methyl, ethyl, propyl, hexyl, or decyl. Alkyl groups are not limited thereto.

[0048] Substituents having carbon-carbon unsaturated double bonds can be, for example, vinylbenzyl (e.g., p-vinylbenzyl or m-vinylbenzyl); vinylphenyl; acrylate; or methacrylate. In particular, substituents having carbon-carbon unsaturated double bonds suitably include vinylbenzyl, vinylphenyl, or methacrylate groups. When the substituent having the carbon-carbon unsaturated double bond is allyl, the reactivity of compound (A2) tends to decrease. Conversely, if the substituent having the carbon-carbon unsaturated double bond is acrylate, the reactivity of compound (A2) tends to become excessively high.

[0049] Suitable specific examples of substituents having carbon-carbon unsaturated double bonds can be functional groups including vinylbenzyl groups. Specifically, substituents having carbon-carbon unsaturated double bonds can be, for example, substituents represented by the following formula (3) or formula (4):

[0050]

[0051]

[0052] The substituent having a carbon-carbon unsaturated double bond can also be a (meth)acrylate group. A (meth)acrylate group is represented, for example, by the following formula (5):

[0053]

[0054] In formula (5), R4 is a hydrogen atom or an alkyl group. The alkyl group is suitably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specifically, for example, the alkyl group is methyl, ethyl, propyl, hexyl, or decyl. Alkyl groups are not limited to these.

[0055] As described above, compound (A2) has a polyphenylene ether chain in its molecule. The polyphenylene ether chain has repeating units, for example, represented by the following formula (6):

[0056]

[0057] In formula (6), m is a number in the range of 1-50. R5 to R8 each independently represent a hydrogen atom, alkyl, alkenyl, alkynyl, formyl, alkylcarbonyl, alkenylcarbonyl, or alkynylcarbonyl. Each of R5 to R8 is preferably a hydrogen atom or an alkyl group. For example, an alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specifically, an alkyl group can be, for example, methyl, ethyl, propyl, hexyl, or decyl. An alkenyl group is preferably an alkenyl group having 2 to 18 carbon atoms, and more preferably an alkenyl group having 2 to 10 carbon atoms. Specifically, an alkenyl group can be, for example, vinyl, allyl, or 3-butenyl. An alkynyl group is preferably an alkynyl group having 2 to 18 carbon atoms, and more preferably an alkynyl group having 2 to 10 carbon atoms. Specifically, an alkynyl group is, for example, ethynyl or prop-2-yn-1-yl (propynyl). Alkyl carbonyl groups can be carbonyl groups substituted with alkyl groups. For example, alkyl carbonyl groups having 2 to 18 carbon atoms are suitable, and alkyl carbonyl groups having 2 to 10 carbon atoms are more suitable. Specifically, alkyl carbonyl groups can be, for example, acetyl, propionyl, butyryl, isobutyryl, neopentyl, hexanoyl, octanoyl, or cyclohexyl carbonyl groups. For example, alkenyl carbonyl groups can be carbonyl groups substituted with alkenyl groups, and are preferably alkenyl carbonyl groups having 3 to 18 carbon atoms, and more preferably alkenyl carbonyl groups having 3 to 10 carbon atoms. Specifically, alkenyl carbonyl groups can be, for example, acryloyl, methacryl, or crotonyl groups. For example, alkynyl carbonyl groups can be carbonyl groups substituted with alkynyl groups, and are preferably alkynyl carbonyl groups having 3 to 18 carbon atoms, and more preferably alkynyl carbonyl groups having 3 to 10 carbon atoms. Specifically, alkynyl carbonyl groups can be, for example, propynyl groups. The alkyl, alkenyl, alkynyl, formyl, alkyl carbonyl, alkenyl carbonyl, and alkynyl carbonyl groups are not limited to these.

[0058] The weight-average molecular weight (Mw) of compound (A2) is suitably in the range of 500 to 5000, more preferably in the range of 500 to 2000, and even more preferably in the range of 1000 to 2000. The weight-average molecular weight is a value obtained by converting measurements obtained by gel permeation chromatography (GPC) into the equivalent weight of polystyrene. If compound (A2) has repeating units in its molecule represented by formula (6), then m in formula (6) is suitably a value that makes the weight-average molecular weight of compound (A2) fall within any of the aforementioned suitable ranges. Specifically, m is suitably in the range of 1 to 50. If the weight-average molecular weight of compound (A2) is within such a range, then compound (A2) imparts excellent dielectric properties to the cured product of composition (X) through the polyphenylene ether chain, thereby improving the heat resistance of the cured product and improving the moldability of composition (X). The reasoning is as follows. If the weight-average molecular weight of the unmodified polyphenylene ether is in the range of approximately 500-5000, the polyphenylene ether has a low molecular weight, which tends to reduce the heat resistance of the cured product. On the other hand, compound (A2) has unsaturated double bonds at the ends, which improves the heat resistance of the cured product. Furthermore, if the weight-average molecular weight of compound (A2) is below 5000, the moldability of composition (X) will not be easily inhibited. Therefore, compound (A2) will improve not only the heat resistance of the cured product but also the moldability of composition (X). If the weight-average molecular weight of compound (A2) is above 500, the glass transition temperature of the cured product is not easily reduced, so the cured product tends to have good heat resistance. In addition, this reduces the possibility of shortening the polyphenylene ether chain in compound (A2), thereby allowing the cured product to maintain excellent dielectric properties due to the presence of the polyphenylene ether chain. Furthermore, if the weight-average molecular weight is below 5000, compound (A2) is easily soluble in solvents, thereby reducing the possibility of a decrease in the storage stability of composition (X). In addition, compound (A2) does not tend to increase the viscosity of composition (X), thereby facilitating the good formability of composition (X).

[0059] The average number of substituents per molecule of compound (A2) having carbon-carbon unsaturated double bonds (the number of terminal functional groups) is suitably 1 to 5, more preferably 1 to 3, and even more preferably 1.5 to 3. This is beneficial in ensuring sufficiently high heat resistance of the cured product of composition (X) and reducing the possibility that the reactivity and viscosity of compound (A2) will become excessively high. Additionally, this reduces the possibility of unreacted unsaturated double bonds remaining after composition (X) has cured. Note that the number of terminal functional groups in compound (A2) is the average number of substituents per molecule in 1 mole of compound (A2). For example, when compound (A2) is synthesized by modifying polyphenylene ether, the number of terminal functional groups can be obtained by measuring the number of hydroxyl groups in compound (A2) and calculating the reduction in the number of hydroxyl groups in compound (A2) from the number of hydroxyl groups in unmodified polyphenylene ether. The reduction compared to the number of hydroxyl groups in unmodified polyphenylene ether is the number of terminal functional groups. The number of remaining hydroxyl groups in compound (A2) can be determined by the UV absorption of a mixed solution obtained by adding a quaternary ammonium salt (tetraethylammonium hydroxide) associated with the hydroxyl group to a solution of compound (A2).

[0060] The intrinsic viscosity of compound (A2) is suitably in the range of 0.03 dl / g to 0.12 dl / g, more preferably in the range of 0.04 dl / g to 0.11 dl / g, and even more preferably in the range of 0.06 dl / g to 0.095 dl / g. This further increases the possibility of reducing the dielectric constant and dielectric loss tangent of the cured product of composition (X). Additionally, the formability of composition (X) can be improved by imparting sufficient flowability to composition (X).

[0061] The intrinsic viscosity is the intrinsic viscosity measured in dichloromethane at 25°C. More specifically, the intrinsic viscosity is the viscosity of a solution prepared by dissolving compound (A2) in dichloromethane at a concentration of 0.18 g / 45 ml at 25°C. This viscosity is measured using, for example, a viscometer manufactured by Schott, the AVS500 Visco System.

[0062] The method used to synthesize compound (A2) is not limited to any specific method. For example, compound (A2) can be synthesized by reacting polyphenylene ether with a compound having a structure in which substituents containing carbon-carbon unsaturated double bonds are bonded to halogen atoms. More specifically, polyphenylene ether is combined with and dissolved in a solvent with a compound having a structure in which substituents containing carbon-carbon unsaturated double bonds are bonded to halogen atoms, and the mixture is stirred. As a result, the polyphenylene ether reacts with the compound having a structure in which substituents containing carbon-carbon unsaturated double bonds are bonded to each other, thereby forming compound (A2).

[0063] Examples of compounds having this structure in which substituents with carbon-carbon unsaturated double bonds and halogen atoms are bonded to each other include p-chloromethylstyrene and m-chloromethylstyrene. There are no particular limitations on the starting material polyphenylene ether, as long as it can ultimately synthesize compound (A2). The polyphenylene ether contains at least one from the group consisting of: polyphenylene ethers composed of at least one of bifunctional phenols and trifunctional phenols with 2,6-dimethylphenol, and polyphenylene ethers such as poly(2,6-dimethyl-1,4-phenyleneoxy). Bifunctional phenols are phenolic compounds having two phenolic hydroxyl groups per molecule and containing, for example, at least one from the group consisting of: tetramethylbisphenol A, biphenylhydrazine, and tetraalkylbiphenylhydrazine. Trifunctional phenols are phenolic compounds having three phenolic hydroxyl groups per molecule.

[0064] Of particular suitability is that compound (A) contains both copolymer (A1) and compound (A2). This significantly increases the potential for reducing the dielectric constant and dielectric loss tangent of the cured product.

[0065] If compound (A) contains both copolymer (A1) and compound (A2), the content of copolymer (A1) relative to 100 parts by mass of compound (A2) is suitably in the range of 10 to 200 parts by mass. Setting the content of copolymer (A1) to 10 parts by mass or more not only significantly improves moldability, especially when molding composition (X) into a film shape, but also significantly reduces the dielectric constant of the cured product. Setting the content of copolymer (A1) to 200 parts by mass or less allows for improved flexibility of the resin sheet made from composition (X) and facilitates a particularly easy reduction of the linear expansion coefficient of the cured product.

[0066] Compound (A) may contain only copolymer (A1) and compound (A2). Alternatively, compound (A) may contain not only copolymer (A1) and compound (A2), but also other compounds (A3) besides copolymer (A1) and compound (A2).

[0067] If compound (A) contains compound (A3), then compound (A3) suitably contains at least one compound selected from the group consisting of: monofunctional compounds and polyfunctional compounds. If compound (A3) contains a monofunctional compound, then the monofunctional compound contains at least one compound selected from the group consisting of: 1-octadecene, stearyl methacrylate, dicyclopentyl methacrylate, and isobornyl methacrylate. If compound (A3) contains a polyfunctional compound, then the polyfunctional compound suitably contains at least one component selected from the group consisting of: divinylbenzene, dicyclopentadiene, methylcyclopentadiene dimer, trivinylcyclohexane, triallyl isocyanurate (TAIC), dicyclopentadiene-dimethyl methacrylate, nonanediol dimethacrylate, 1,3-diisopropenylbenzene, and trimethylolpropane triacrylate. Examples of commercially available polyfunctional compounds include TA-G, LDAIC, and DD-1 manufactured by Shikoku Chemicals Co., Ltd. If compound (A3) contains polyfunctional compounds, it is easy to improve the flame retardancy of the cured product of composition (X).

[0068] Compound (A3) may contain maleimide. This is beneficial for improving the flame retardancy of the cured product. Maleimide contains at least one compound selected from the group consisting of: phenylmaleimide, cyclohexylmaleimide, 4,4′-diphenylmethane bismaleimide, m-phenyl bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, and 1,6-bismaleimide-(2,2,4-trimethyl)hexane. Examples of commercially available bismaleimides include BMI-689 and BMI-3000 (product names manufactured by DESIGNER MOLECULES), and MIR-3000 manufactured by Nippon Kayaku Co., Ltd.

[0069] If compound (A) contains copolymer (A1), compound (A2), and compound (A3), the content of compound (A3) is suitably in the range of 1 to 50 parts by mass relative to a total of 100 parts by mass of copolymer (A1) and compound (A2). Setting the content of compound (A3) to 1 part by mass or more results in improved heat resistance of the cured product of composition (X). Setting the content of compound (A3) to 50 parts by mass or less results in a decrease in the dielectric constant and dielectric loss tangent of the cured product of composition (X) and reduces the likelihood that the resin sheet formed from composition (X) will become sticky.

[0070] Composition (X) suitably contains a thermal free radical polymerization initiator (B). The thermal free radical polymerization initiator (B) can promote the thermal free radical polymerization reaction of compound (A) by generating an active substance when composition (X) is heated. Composition (X) does not necessarily need to contain the thermal free radical polymerization initiator (B), as long as compound (A) contains a component that readily generates an active substance when compound (A) is heated.

[0071] The thermal free radical polymerization initiator (B) may contain at least one of, for example, an azo compound and a peroxide. The azo compound may contain, for example, azobisisobutyronitrile (AIBN). The peroxide may contain at least one compound selected from the group consisting of: α,α′-di(tert-butylperoxy)diisopropylbenzene, α,α′-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, benzoyl peroxide, 3,3′,5,5′-tetramethyl-1,4-biphenylquinone, chloroquinone, 2,4,6-tritert-butylphenoxy, tert-butylperoxyisopropyl carbonate, tert-pentyl peroxydecanoate, tert-pentyl peroxypentanoate, tert-pentyl peroxy-2-ethylhexanoate, tert-pentyl peroxyoctanoate, tert-pentyl peroxyacetate, tert-pentyl peroxyisononanoate, tert-pentyl peroxybenzoate, tert-pentyl peroxyisopropyl carbonate, ditert-pentyl peroxide, and 1,1-di(tert-pentylperoxy)cyclohexane. The compounds that the thermal free radical polymerization initiator (B) may contain are not limited to those listed here.

[0072] The thermal free radical polymerization initiator (B) suitably contains a peroxide. This increases the possibility of raising the glass transition temperature of the cured product.

[0073] If the thermal free radical polymerization initiator (B) contains a peroxide, the peroxide suitably contains at least one compound selected from the group consisting of tert-amyl peroxide-based polymerization initiators and tert-hexyl peroxide-based polymerization initiators. In this case, the peroxide hardly increases the dielectric loss tangent of the cured product while increasing the glass transition temperature. Azo compounds are also suitable because they hardly increase the dielectric loss tangent of the cured product.

[0074] The tert-amyl peroxide polymerization initiator may contain at least one compound selected from the group consisting of: tert-amyl peroxynedecanoate, tert-amyl peroxynepentanoate, tert-amyl peroxy-2-ethylhexanoate, tert-amyl peroxyoctanoate, tert-amyl peroxyacetate, tert-amyl peroxyisononanoate, tert-amyl peroxybenzoate, tert-amyl peroxyisopropyl carbonate, di-tert-amyl peroxy, and 1,1-di(tert-amylperoxy)cyclohexane.

[0075] Tertiary hexyl peroxide-based polymerization initiators may contain, for example, di-tert-hexyl peroxide.

[0076] If the composition (X) contains a thermal free radical polymerization initiator (B), the content of the thermal free radical polymerization initiator (B) relative to 100 parts by mass of the compound (A) may be in the range of, for example, 0.1 parts by mass to 5 parts by mass.

[0077] As described above, the organic free radical compound (C) is beneficial for improving the storage stability of the composition (X) and its dried and semi-cured products, and also beneficial for reducing the increase in the linear expansion coefficient of the cured products involved in storage and suppressing the decrease in glass transition temperature.

[0078] The organic free radical compound (C) suitably contains an organic nitric oxide free radical compound (C1). This is particularly beneficial to the organic free radical compound (C) that has the above-mentioned effects.

[0079] The organic nitroxide radical compound (C1) may contain at least one compound selected from the group consisting of: a compound represented by formula (7); a compound represented by formula (8); a compound represented by formula (9); a compound represented by formula (10); and a compound represented by formula (11). The compounds that the organic nitroxide radical compound (C1) may contain are not limited thereto.

[0080] In equation (10), n is a number in the range of 1 to 18. In equation (11), R is hydrogen or hydroxyl.

[0081]

[0082]

[0083] The organic nitroxide radical compound (C1) suitably contains at least one component selected from the group consisting of: 2,2,6,6-tetramethylpiperidine-1-oxy and its derivatives. For example, the organic nitroxide radical compound (C1) suitably contains at least one component selected from the group consisting of: a compound represented by formula (9), a compound represented by formula (10), and a compound represented by formula (11).

[0084] Organic nitroxide radical compounds (C1) particularly suitably contain compounds represented by formula (11). More suitably, R in formula (11) is hydrogen. This is particularly advantageous for improving the dielectric properties of the cured product.

[0085] The content of organic free radical compound (C) relative to compound (A) is suitably in the range of 0.01% by mass to 5.0% by mass. If its content is 0.05% by mass or higher, moldability can be improved. If its content is 5.0% by mass or lower, the coefficient of linear expansion of the cured product can be reduced. The content of organic free radical compound (C) is more preferably in the range of 0.05% by mass to 4.0% by mass, and even more preferably in the range of 0.05% by mass to 3.0% by mass.

[0086] Composition (X) may contain a metal passivator (D). When composition (X), its dried product, its semi-cured product, or its cured product comes into contact with a conductor, such as a conductor line, the metal passivator (D) can deactivate ions (e.g., copper ions) originating from the conductor. Therefore, the likelihood of composition (X), its dried product, its semi-cured product, or its cured product undergoing a redox reaction with ions (e.g., copper ions) in the conductor to generate highly polar components is reduced. This reduces the likelihood of an increase in the dielectric loss tangent of the cured product due to the presence of ions originating from the conductor. In particular, if composition (X) contains a copolymer (A1), the copolymer (A1) initially tends to undergo a redox reaction with ions. However, the metal passivator (D) reduces the likelihood of a redox reaction between the copolymer (A1) and the ions. That is, when composition (X) contains a copolymer (A1), the metal passivator (D) achieves a particularly advantageous effect.

[0087] The metal passivating agent (D) contains at least one compound selected from the group consisting of: 2-hydroxy-N-1H-1,2,3-triazol-3-ylbenzamide, N′1,N′12-bis(2-hydroxybenzoyl)dodecanedihydrazide, and N,N′-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazide. Examples of commercially available metal passivating agents (D) include ADEKA STAB CDA-1, ADEKA STAB CDA-6, and ADEKA STAB CDA-10 manufactured by ADEKA CORPORATION. The components that the metal passivating agent (D) may contain are not limited thereto.

[0088] The content of the metal passivating agent (D) relative to compound (A) is suitably in the range of 0.01% by mass to 5.0% by mass. If the content of the metal passivating agent (D) is 0.01% by mass or more, the increase in dielectric loss tangent during high-temperature treatment of the cured product can be suppressed. If the content of the metal passivating agent (D) is 5.0% by mass or less, a cured product with low dielectric constant and low dielectric loss tangent can be obtained. The content of the metal passivating agent (D) is more preferably in the range of 0.01% by mass to 3.0% by mass, and even more preferably in the range of 0.05% by mass to 2.0% by mass.

[0089] Composition (X) may contain a styrene-based elastomer (E). The elastomer (E) is, for example, a copolymer comprising olefin units and styrene units. The olefin units are derived from olefin monomers, and the styrene units are derived from styrene monomers. The styrene monomer is at least one selected from the group consisting of styrene and styrene having substituents. The substituents are, for example, alkyl groups, such as methyl groups. In particular, the styrene monomer suitably contains at least one of styrene and methylstyrene. Methylstyrene includes at least one selected from the group consisting of α-methylstyrene, β-methylstyrene, 2-methylstyrene, 3-methylstyrene, and 4-methylstyrene.

[0090] When composition (X) contains copolymer (A1) and compound (A2), elastomer (E) can improve the compatibility between copolymer (A1) and compound (A2). Therefore, elastomer (E) can improve the flame retardancy of the cured product. Styrene-based elastomers can not only improve the formability of composition (X) when molding it into sheets to form resin sheets, but also improve the toughness of its semi-cured and cured products.

[0091] The elastomer (E) can be a random copolymer or a block copolymer. If the elastomer (E) is a random copolymer, then the elastomer (E) is a copolymer in which a plurality of olefin units and a plurality of styrene units are randomly arranged. If the elastomer (E) is a block copolymer, then the elastomer (E) is a copolymer in which one or more olefin blocks and one or more styrene blocks are arranged. The olefin blocks consist of a plurality of olefin units, and the styrene blocks consist of a plurality of styrene units. If the elastomer (E) is a random copolymer, the elastomer (E) can be prepared, for example, by polymerizing the olefin monomers and styrene monomers by emulsion polymerization or solution polymerization.

[0092] If the elastomer (E) is a block copolymer, the elastomer (E) can be prepared, for example, by block polymerization of olefin monomers and styrene monomers in an inert solvent in the presence of a lithium catalyst.

[0093] The plurality of olefin units in the elastomer (E) suitably include at least one selected from the group consisting of: ethylene units, propylene units, butene units, α-olefin units, butadiene units, hydrogenated butadiene units, isoprene units, and hydrogenated isoprene units. The olefin units particularly suitably include hydrogenated isoprene units. This is beneficial for improving the stability of the composition (X).

[0094] The mass ratio of olefin units to styrene units in the elastomer (E) is suitably in the range of 30:70 to 90:10, and more preferably in the range of 60:40 to 85:15. This allows for a particularly significant improvement in the compatibility between the copolymer (A1) and the compound (A2).

[0095] The content of elastomer (E) in composition (X) can be appropriately set. Specifically, when composition (X) contains copolymer (A1), compound (A2), and elastomer (E), the content of elastomer (E) is suitably in the range of 5 to 100 parts by mass relative to a total of 100 parts by mass of copolymer (A1) and compound (A2). If the content of elastomer (E) is 5 parts by mass or more, the elastomer (E) tends to sufficiently improve the compatibility between copolymer (A1) and compound (A2), thereby enabling composition (X) to be molded into a film shape with good stability. If the content of elastomer (E) is 100 parts by mass or less, the increase in the linear expansion coefficient of the cured product can be reduced, and its heat resistance and flame retardancy can be improved.

[0096] The composition (X) may contain an inorganic filler (F). The inorganic filler (F) can reduce the linear expansion coefficient of the cured product, further improve the dielectric properties of the cured product, and enhance the heat resistance and flame retardancy of the cured product.

[0097] Examples of inorganic fillers (F) include at least one material selected from the group consisting of: silica, alumina, talc, aluminum hydroxide, magnesium hydroxide, titanium dioxide, mica, aluminum borate, barium sulfate, boron nitride, forsterite, zinc oxide, magnesium oxide, and calcium carbonate.

[0098] The inorganic filler (F) is suitably surface-treated with a surface-treatment agent having polymerizable unsaturated groups. In other words, the particles of the inorganic filler (F) suitably have polymerizable unsaturated groups derived from the surface-treatment agent on their surface. The polymerizable unsaturated groups include, for example, at least one group selected from the group consisting of: vinyl, allyl, methacrylate, styrene, acryloyl, methacryl, and maleimide. Examples of surface-treatment agents include silane coupling agents having polymerizable unsaturated groups. The groups that the polymerizable unsaturated groups may contain and the components that the surface-treatment agent may contain are not limited thereto.

[0099] If the inorganic filler (F) is surface-treated with a surface-treatment agent containing polymerizable unsaturated groups, the polymerizable unsaturated groups in the inorganic filler (F) can react with the compound (A), thereby enabling the cured product to have an increased crosslinking density. Therefore, the inorganic filler (F) may further reduce the linear expansion coefficient of the cured product and further increase the glass transition temperature of the cured product.

[0100] If the composition (X) contains an inorganic filler (F), the content of the inorganic filler (F) is suitably in the range of 30 to 500 parts by mass relative to a total of 100 parts by mass of compound (A). If the content of the inorganic filler (F) is 30 parts by mass or more, the inorganic filler (F) can particularly significantly reduce the coefficient of linear expansion of the cured product, particularly easily improve the dielectric properties of the cured product, and particularly significantly improve the heat resistance and flame retardancy of the cured product. If the content of the inorganic filler (F) is 500 parts by mass or less, the composition (X) is able to easily maintain its flowability during molding.

[0101] Composition (X) may contain a flame retardant (G). The presence of a flame retardant (G) may improve the flame retardancy of composition (X).

[0102] In this embodiment, as described above, the flame retardancy of the cured product can be improved by the organic free radical compound (C). If the composition (X) contains a flame retardant (G), the flame retardancy of the cured product can be further improved. Furthermore, because the flame retardancy of the cured product is improved by the organic free radical compound (C), the content of the flame retardant (G) when it is added to the composition (X) can be reduced.

[0103] The flame retardant (G) may include a flame retardant (F1) containing bromine or phosphorus. In this case, the flame retardant (F1) can improve the flame retardancy of the cured product while reducing the dielectric constant of the cured product. The flame retardant (F1) may contain at least one of a bromine-containing flame retardant (F11) or a phosphorus-containing flame retardant (F12).

[0104] Flame retardant (F11) suitably contains, for example, an aromatic bromine compound. Flame retardant (F11) suitably contains at least one selected from the group consisting of: decabromodiphenyl ethane, 4,4-dibromobiphenyl and ethylidene-bistetrabromophthalimide.

[0105] If composition (X) contains flame retardant (F1), the bromine content in flame retardant (F1) is suitably in the range of 8% by mass to 20% by mass relative to composition (X). This significantly improves the flame retardancy of the cured product and significantly reduces the likelihood of bromine dissociating from the cured product when heated.

[0106] The flame retardant (F12) contains at least one of, for example, an incompatible phosphorus compound or a compatible phosphorus compound.

[0107] Incompatible phosphorus compounds suitably contain, for example, phosphine oxide compounds having two or more diphenylphosphine oxide groups per molecule. The melting point of this phosphine oxide compound is suitably above 280°C. Phosphine oxide compounds suitably include compounds having one or more linking groups selected from the group consisting of: phenylene, xylene, biphenylene, naphthylene, methylene, and ethylene, and having a structure in which two or more diphenylphosphine oxide groups are linked.

[0108] The compatible phosphorus compound suitably contains at least one selected from the group consisting of: phosphate esters, phosphazene compounds, phosphites, and phosphine compounds.

[0109] If composition (X) contains flame retardant (F12), the phosphorus content in flame retardant (F12) is suitably in the range of 2.0% by mass to 6.0% by mass relative to composition (X). This improves the flame retardancy of the cured product and reduces the likelihood of phosphorus dissociating from the cured product when heated.

[0110] The composition (X) may contain a solvent. The solvent suitably contains at least one component selected from the group consisting of aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and ketone solvents. If the composition (X) contains a solvent, the moldability of the composition (X) when forming it into a sheet shape can be readily improved.

[0111] Composition (X) may contain suitable components other than those described above. For example, composition (X) may contain at least one component selected from the group consisting of: defoamers such as silicone defoamers or acrylate defoamers, heat stabilizers, antistatic agents, ultraviolet absorbers, dyes, pigments, lubricants, and wetting and dispersing agents. Optionally, composition (X) may contain other components besides those described above.

[0112] The resin sheet according to this embodiment comprises a dried or semi-cured product of composition (X). The resin sheet can be used as a laminate or a material for printed circuit boards. An insulating layer comprising a cured product of composition (X) can be formed by curing the resin sheet.

[0113] To manufacture a resin sheet, for example, firstly, the composition (X) is shaped into a sheet. Examples of methods for shaping the composition (X) include coating. However, this is merely an example and should not be construed as limiting. Next, the composition (X) is heated to dry or semi-cure it. In this way, a resin sheet containing a dried or semi-cured product of the composition (X) can be obtained. The heating temperature only needs to be high enough to dry the solvent in the composition (X) or to convert the composition (X) into a semi-cured product, and can be, for example, in the range of 100°C to 160°C. For example, the duration of heating can be in the range of 5 to 10 minutes.

[0114] As described above, an insulating layer comprising the cured product of composition (X) can be formed by heating and curing the resin sheet. For example, the heating temperature can be in the range of 160°C to 220°C, and preferably in the range of 180°C to 220°C. For example, the heating duration can be in the range of 30 minutes to 240 minutes, and preferably in the range of 60 minutes to 240 minutes.

[0115] The temperature at which the resin sheet exhibits its lowest melt viscosity is suitably equal to or higher than 140°C. This is beneficial for maintaining a low viscosity as the resin sheet is heated and melted. This temperature is more preferably equal to or higher than 160°C. Furthermore, the temperature at which the resin sheet exhibits its lowest melt viscosity is suitably equal to or lower than 180°C. This prevents the heating temperature used to solidify the resin sheet in order to melt it from becoming too high. Furthermore, the temperature at which the resin sheet exhibits its lowest melt viscosity can be achieved through the aforementioned chemical composition of composition (X). The temperature at which the resin sheet exhibits its lowest melt viscosity can be confirmed by using a rheometer (model Rheosol G-3000 manufactured by UBM Co., Ltd.) and parallel plates, measuring the melt viscosity of the resin sheet over a heating width of 50°C to 250°C under measurement conditions including a heating rate of 3°C / min and a frequency of 0.009 rad / s. The temperature at which the resin sheet exhibits its lowest melt viscosity can be confirmed based on a melt viscosity profile showing the relationship between temperature and the resulting melt viscosity.

[0116] Resin sheets can be used as adhesive sheets for bonding substrates such as multiple printed circuit boards. Specifically, firstly, for example, composition (X) is coated onto a support film 8 made of polyethylene terephthalate and shaped into a sheet, which is then dried or semi-cured, thereby forming a resin sheet 7 (see [link to documentation]). Figure 1A). Next, the resin sheet 7 is adhered to a substrate (hereinafter referred to as "first substrate 91"), such as a printed circuit board, and then the support film 8 is peeled off from the resin sheet 7. Next, another substrate (hereinafter referred to as "second substrate 92") is stacked on top of the resin sheet 7 on the first substrate 91. In this way, a multilayer stack including the first substrate 91, the second substrate 92, and the resin sheet 7 between the first substrate 91 and the second substrate 92 is obtained. This multilayer stack is hot-pressed to melt and then solidify the resin sheet 7, thereby forming an insulating layer 30 (as an adhesive layer). This allows the first substrate 91 and the second substrate 92 to be bonded together through the insulating layer 30. In this case, if at least one surface of the first substrate 91 or the second substrate 92 (which is stacked on top of the resin sheet 7) has conductor lines 93, the resin sheet 7 covering the conductor lines 93 is melted and then solidified, thereby allowing the insulating layer 30 made of the resin sheet 7 to adequately seal the gaps of the conductor lines 93. Bonding the substrate with the resin sheet 7 in this way makes it possible to manufacture a multilayer printed circuit board 3, such as Figure 1 The multilayer printed circuit board shown in B. The multilayer printed circuit board 3 includes: an insulating layer 94 and conductor lines 93 derived from a first substrate 91; an insulating layer 94 and conductor lines 93 derived from a second substrate 92; and an insulating layer 30 formed by a resin sheet 7 between the first substrate 91 and the second substrate 92.

[0117] Next, the metal foil sheet 1 containing resin will be described. For example... Figure 2 As shown in Figure A, the resin-containing metal foil sheet 1 includes a metal foil sheet 10 and a resin layer 20 stacked on top of the metal foil sheet 10. The resin layer 20 includes the aforementioned resin sheet 7. A laminate or printed circuit board can be formed based on this resin-containing metal foil sheet 1.

[0118] For example, the metal foil sheet 10 may be a copper foil sheet. For example, the thickness of the metal foil sheet 10 may be in the range of 2 μm to 105 μm, and its thickness is suitably in the range of 5 μm to 35 μm. The metal foil sheet 10 may be, for example, a copper foil sheet with a thickness of 2 μm, forming part of a combination of a copper foil sheet with a thickness of 18 μm and a carrier copper foil sheet.

[0119] like Figure 2 The resin layer 20 shown in A includes: a first resin layer 21 stacked on top of the metal foil sheet 10; and a second resin layer 22 stacked on top of the first resin layer 21 and forming the outermost layer of the resin layer 20 on the opposite side of the metal foil sheet 10.

[0120] The second resin layer 22 is made of resin sheet 7. The first resin layer 21 has a different composition from the second resin layer. In this case, the resin layer 20 and the insulating layer formed by the resin layer 20 are endowed with properties corresponding to the composition of the first resin layer 21. For example, the first resin layer 21 endows the insulating layer with excellent flexibility, thereby enabling the formation of a flexible laminate or printed circuit board from the resin-containing metal foil sheet 1.

[0121] For example, the thickness of the first resin layer 21 can be in the range of 1 μm to 50 μm. For example, the thickness of the second resin layer 22 can be in the range of 5 μm to 200 μm, and its thickness is suitably in the range of 10 μm to 150 μm.

[0122] The first resin layer 21 comprises at least one component selected from the group consisting of (hereinafter also referred to as "specific resin component"): liquid crystal polymer resin, polyimide resin, polyamide-imide resin, fluoropolymer resin, and polyphenylene ether resin. For example, the first resin layer 21 may be made of a resin solution or sheet material comprising the above components. Optionally, the sheet material may include a substrate such as a glass cloth sheet and may be reinforced with a substrate. For example, the sheet material may be a prepreg. The first resin layer 21 may be formed, for example, by coating a resin solution onto a metal foil sheet 10 and drying the resin solution, or by laminating the sheet material over the metal foil sheet 10 and then hot-pressing the sheet material.

[0123] The first resin layer 21 can be as follows: Figure 2 A represents a single layer, but can include multiple layers. For example, as shown in Figure A. Figure 2 As shown in Figure B, the first resin layer 21 may include a first layer 211 and a second layer 212 having different compositions from each other. For example, the first layer 211 and the second layer 212 may each include a specific resin component and may have different compositions from each other. Alternatively, the first resin layer 21 may include three or more layers.

[0124] As described above, the second resin layer 22 can be formed from the resin sheet 7. For example, the composition (X) is coated onto the first resin layer 21 and shaped into a sheet by coating or any other suitable method, and then heated to dry or semi-cure it. In this way, the second resin layer 22 can be formed from the resin sheet 7.

[0125] The resin layer 20 may be a single layer consisting only of the resin sheet 7. In this case, such a resin layer 20 consisting only of the resin layer 7 may be formed, for example, by coating the composition (X) onto the metal foil sheet 10 by a coating method or any other suitable method, shaping the composition (X) into a sheet, and then heating the composition (X) to dry or semi-cure the composition (X).

[0126] The laminate 2 according to this embodiment will now be described. Figure 3 As shown in A-3D, the laminate 2 includes an insulating layer 30 and a metal foil sheet 10.

[0127] The laminate 2 includes a metal foil sheet 10 as its outermost layer. The laminate 2 may include a single metal foil sheet 10 or multiple metal foil sheets 10, either of which is suitable. If the laminate 2 includes multiple metal foil sheets 10, then the laminate 2 includes one of the multiple metal foil sheets 10 as its outermost layer.

[0128] The insulating layer 30 comprises a cured product of composition (X). Optionally, the insulating layer 30 may also comprise a specific resin component.

[0129] Laminate 2 can be as follows Figure 3 The diagrams shown in A and 3B only include one insulating layer 30, or as... Figure 3 The figures C and 3D show more than two insulating layers 30.

[0130] If the laminate 2 comprises only one insulating layer 30, the insulating layer 30 may consist, for example, only a layer of cured product containing composition (X), or may comprise a second layer 302 containing cured product of composition (X) and a first layer 301 other than the second layer 302. For example, the first layer 301 may contain a specific resin component. For example, the thickness of the first layer 301 may be in the range of 1 μm to 50 μm, and for example, the thickness of the second layer 302 may be in the range of 5 μm to 50 μm.

[0131] If the laminate 2 comprises two or more insulating layers 30, at least one of the two or more insulating layers 30 may contain a cured product of composition (X). Additionally, at least one of the two or more insulating layers 30 may contain a specific resin component. Alternatively, at least one of the two or more insulating layers 30 may contain both a cured product of composition (X) and a specific resin component. In this case, at least one of the two or more insulating layers 30 may be a layer including a first layer 301 and a second layer 302 stacked on top of the first layer 301. Each of the two or more insulating layers 30 may contain a specific resin component.

[0132] The material and thickness of the metal foil sheet 10 can be the same as those of the metal foil sheet 10 included in the above-mentioned resin-containing metal foil sheet.

[0133] Forming a laminate 2 comprising an insulating layer 30 containing a cured product of composition (X) is beneficial for improving the heat resistance of the insulating layer 30, reducing the coefficient of linear expansion, and improving the flame retardancy.

[0134] Figure 3The laminate 2 shown in A includes a metal foil sheet 10, a first layer 301, and a second layer 302, which are stacked on top of each other in sequence. Figure 3 The laminate 2 shown in A can be formed, for example, by heating the aforementioned resin-containing metal foil sheet 1. However, this is not the only method for manufacturing the laminate 2. Alternatively, the laminate 2 can also be formed, for example, by sequentially stacking the metal foil sheet 10, a sheet material containing the components of the first layer 301, and the aforementioned resin sheet 7, and then hot-pressing the stack. Alternatively, the metal foil sheet 10, the second layer 302, and the first layer 301 can be sequentially stacked. Optionally, the first layer 301 may comprise two or more layers. In this case, the two layers in direct contact with each other in the first layer 301 may have different compositions.

[0135] Figure 3 The laminate 2 shown in B comprises a metal foil sheet 10 (as a first metal foil sheet 11), an insulating layer 30, and another metal foil sheet 10 (as a second metal foil sheet 12), which are stacked sequentially on top of each other. This laminate 2 can be formed by stacking another metal foil sheet on top of the resin layer 20 of the aforementioned resin-containing metal foil sheet 1, and then hot-pressing the stack. However, this is not the only method for manufacturing the laminate 2. Alternatively, the laminate 2 can also be formed by providing a metal foil sheet 11, a sheet material containing the components of the first layer 301, the aforementioned resin sheet 7, and the second metal foil sheet 12, stacking them sequentially on top of each other, and then hot-pressing the stack.

[0136] Figure 3 The laminate 2 shown in C includes a metal foil sheet 10 (as a first metal foil sheet 11), an insulating layer 30 (as a first insulating layer 31), a conductor layer 50, and another insulating layer 30 (as a second insulating layer 32), which are stacked sequentially on top of each other. The first insulating layer 31 includes a first layer 301 and a second layer 302. The first insulating layer 31 may have the same characteristics as... Figure 3 The insulating layer 30 of the laminate 2 shown in A has the same structure. The second insulating layer 32 comprises at least one component selected from the group consisting of: the cured product of composition (X), liquid crystal polymer resin, polyimide resin, polyamide-imide resin, fluoropolymer resin, and polyphenylene ether resin. The conductor layer 50 is implemented as a conductor line in this embodiment, but it can also be implemented as a metal foil sheet.

[0137] In order to form Figure 3The laminate 2 shown in C provides a core material including, for example, a second insulating layer 32 and a conductor layer 50 (conductor circuit) stacked thereon. The resin layer 20 of the aforementioned resin-containing metal foil sheet 1 is stacked on one surface of the core material facing the conductor 50. The laminate 2 can be formed by hot-pressing the core material and the resin-containing metal foil sheet 1 in this state. In this case, during hot-pressing, the resin flakes 7 in the resin layer 20 of the resin-containing metal foil sheet 1 are melted and then cured while being stacked above the conductor layer 50, thereby allowing the first insulating layer 31 formed by the resin layer 20 to easily and sufficiently close the gaps in the conductor layer 50.

[0138] Note that this is not the only method for manufacturing the laminate 2. Alternatively, for example, a metal foil sheet 10 (as a first metal foil sheet 11), a sheet material containing the components of the first layer 301, the aforementioned resin sheet 7, the conductor layer 50, and a sheet material containing the components of the second insulating layer 32 may be provided. The laminate 2 may also be formed by sequentially stacking these components on top of each other and hot-pressing the stack.

[0139] Figure 3 The laminate 2 shown in D includes a metal foil sheet 10 (as a first metal foil sheet 11), an insulating layer 30 (as a first insulating layer 31), a conductor layer 50, another insulating layer 30 (as a second insulating layer 32), and another metal foil sheet 10 (as a second metal foil sheet 12), which are stacked on top of each other in sequence. The first insulating layer 31 includes a first layer 301 and a second layer 302. The conductor layer 50 is implemented as a conductor line in this embodiment, but it can also be implemented as a metal foil sheet. That is, in addition to Figure 3 In addition to the second metal foil sheet 12, the laminate 2 shown in D also includes the second metal foil sheet 12. Figure 3 The laminate 2 shown in D has the same characteristics as... Figure 3 The laminate shown in C has the same structure as laminate 2.

[0140] To form the laminate 2, a core material is provided in which a second metal foil sheet 12, a second insulating layer 32, and a conductor layer 50 (conductor lines) are stacked on top of each other in sequence. The resin layer 20 of the aforementioned resin-containing metal foil sheet 1 is stacked on one surface of the core material facing the conductor 50. The laminate 2 can be formed by hot-pressing the core material and the resin-containing metal foil sheet 1 in this state. In this case, during hot-pressing, the resin flakes 7 in the resin layer 20 of the resin-containing metal foil sheet 1 are melted and then cured while being stacked on top of the conductor layer 50, thereby allowing the first insulating layer 31 formed by the resin layer 20 to easily and sufficiently close the gaps in the conductor layer 50.

[0141] Note that this is not the only method for manufacturing the laminate 2. Alternatively, for example, a first metal foil sheet 11, a sheet material containing the components of the first layer 301, the aforementioned resin sheet 7, a conductor layer 50, a sheet material containing the components of the second insulating layer, and a second metal foil sheet 12 may be provided. The laminate 2 may also be formed by sequentially stacking these components on top of each other and hot-pressing the stack.

[0142] The structure of laminate 2 is not limited to Figure 3 Any of the specific embodiments shown in A-3D. Alternatively, for example, the laminate 2 may include one or more metal foil sheets 10, two or more conductor layers 50, and three or more insulating layers 30. Each of the conductor layers 50 is interposed between two adjacent insulating layers 30. The metal foil sheets 10 form the outermost layer of the laminate 2. At least one of the three or more insulating layers 30 contains a cured product of composition (X). For example, at least one of the three or more insulating layers 30 may contain a specific resin component.

[0143] Next, the printed circuit board 3 according to this embodiment will be described. For example... Figure 4 As shown in A-4D, the printed circuit board 3 includes an insulating layer 30 and conductive lines 60. The printed circuit board 3 includes conductive lines 60 as its outermost layer. The insulating layer 30 contains a cured product of composition (X). This is beneficial for improving the heat resistance of the insulating layer 30, reducing its coefficient of linear expansion, and improving its flame retardancy.

[0144] Printed circuit board 3 can be like Figure 4 Figures A and 4B show a single insulating layer 30, or may be as follows: Figure 4 Figures C and 4D show a plurality of insulating layers 30. If the printed circuit board 3 includes a plurality of insulating layers 30, at least one of the plurality of insulating layers 30 contains composition (X). In addition, at least one of the insulating layers 30 suitably contains a specific resin component. Figure 4 The printed circuit board 3 shown in C and 4D includes one or more conductor lines 60 and two or more insulating layers 30, and is therefore also a multilayer printed circuit board 4.

[0145] The insulating layer 30 can be implemented as a single layer or multiple layers, whichever is appropriate. Figure 4 The printed circuit board 3 shown in A-4D includes an insulating layer 30 consisting of a first layer 301 and a second layer 302 stacked on top of the first layer 301. The insulating layer 30 has the same structure as the insulating layer 30 of the laminate 2 described above.

[0146] The following will describe it in more detail. Figure 4 Printed circuit board 3 shown in A-4D.

[0147] Figure 4The printed circuit board 3 shown in Figure A includes conductor lines 60, a first layer 301, and a second layer 302, which are stacked on top of each other. Except that the printed circuit board 3 includes conductor lines 60 instead of metal foil sheet 10, the printed circuit board 3 has the same... Figure 3 The laminate 2 shown in Figure A has the same structure. The printed circuit board 3 can be manufactured in the following ways: for example, by... Figure 3 Excess portions of the metal foil sheet 10 of the laminate 2 shown in A are removed (e.g., etched) to form conductor lines 60.

[0148] Figure 4 The printed circuit board 3 shown in B includes conductor lines 60, an insulating layer 30, and a conductor layer 50, which are stacked on top of each other in sequence. Except that the printed circuit board 3 includes conductor lines 60 instead of metal foil sheet 10 and includes conductor layer 50 (second conductor layer 52) instead of second metal foil sheet 12, the printed circuit board 3 has the same characteristics as... Figure 3 The laminate 2 shown in B has the same structure. The printed circuit board 3 can be manufactured in the following ways: for example, by... Figure 3 Excess portions of the first metal foil sheet 11 of the laminate 2 shown in B are removed (e.g., etched) to form conductor lines 60.

[0149] Figure 4 The printed circuit board 3 shown in C includes conductor lines 60, an insulating layer 30 (first insulating layer 31), a conductor layer 50, and another insulating layer 30 (second insulating layer 32), which are stacked on top of each other in sequence. Except that the printed circuit board 3 includes conductor lines 60 instead of metal foil sheet 10, the printed circuit board 3 has the same characteristics as... Figure 3 The laminate 2 shown in C has the same structure. The printed circuit board 3 can be manufactured in the following ways: for example, by... Figure 3 Excess portions of the metal foil sheet 10 of the laminate 2 shown in C are removed (e.g., etched) to form conductor lines 60.

[0150] Figure 4 The printed circuit board 3 shown in Figure D includes conductor lines 60, an insulating layer 30 (first insulating layer 31), a conductor layer 50 (first conductor layer 51), an insulating layer 30 (second insulating layer 32), and another conductor layer 50 (second conductor layer 52), which are stacked on top of each other in sequence. Except that the printed circuit board 3 includes conductor lines 60 instead of metal foil sheet 10 and includes conductor layer 50 (second conductor layer 52) instead of second metal foil sheet 12, the printed circuit board 3 has the same characteristics as... Figure 3 The laminate 2 shown in D has the same structure. The printed circuit board 3 can be manufactured in the following ways: for example, by... Figure 3 Excess portions of the first metal foil sheet 11 of the laminate 2 shown in D are removed (e.g., etched) to form conductor lines 60.

[0151] Figure 4 The printed circuit board 3 shown in C and 4D each includes two insulating layers 30. However, this is merely an example and should not be construed as limiting. Alternatively, the printed circuit board 3 may include more than three insulating layers 30. Example

[0152] 1. Preparation of the composition and formation of resin sheets

[0153] A composition with a solids concentration of 25% by mass was obtained by dissolving the components shown in the “Composition” column of Tables 1 to 4 in toluene. The composition was coated onto a polyethylene terephthalate film using a comma coater and a dryer connected thereto, and then the composition was heated at 110°C for 5 minutes to form a resin sheet with a thickness of 50 μm on the polyethylene terephthalate film.

[0154] The details of each component shown in Table 1-4 are as follows.

[0155] • Copolymer 1: Ethylene-propylene-diene copolymer with a Mooney viscosity (ML(1+4) 100°C) of 15, an ethylene content of 72%, and a diene content of 3.6%; X-3012P manufactured by Mitsui Chemicals, Inc.

[0156] • Copolymer 2: Ethylene-propylene-diene copolymer with a Mooney viscosity (ML(1+4)100℃) of 20, an ethylene content of 77%, and a diene content of 10.4%; K-9720 manufactured by Mitsui Chemicals, Inc.

[0157] • PPE1: End-group modified polyphenylene ether compound (styrene-modified polyphenylene ether compound) with a number average molecular weight of 1200; OPE-2St 1200 manufactured by Mitsubishi Gas Chemical Company, Inc.

[0158] • PPE2: End-group modified polyphenylene ether compound (styrene-modified polyphenylene ether compound) with a number average molecular weight of 2400; OPE-2St 2400 manufactured by Mitsubishi Gas Chemical Company, Inc.

[0159] • PPE3: End-group modified polyphenylene ether compound (methacryloyl modified polyphenylene ether compound) with a number average molecular weight of 1600; SA-9000 manufactured by SABIC Innovative Plastics;

[0160] • Unsaturated compound 1: Triallyl isocyanurate; TAIC produced by Mitsubishi Chemical Corporation;

[0161] • Unsaturated compound 2: Bismaleimide; BMI-689 manufactured by DESIGNER MOLECULES;

[0162] • Unsaturated compound 3: 1-Octadene;

[0163] • Unsaturated compound 4: 1,3-diisopropenylbenzene;

[0164] • Unsaturated compound 5: Dicyclopentyl methacrylate;

[0165] • Unsaturated compound 6: Trimethylolpropane triacrylate;

[0166] • Thermal free radical polymerization initiator 1: di-tert-hexyl peroxide; Perhexyl D produced by NOF CORPORATION;

[0167] • Thermal free radical polymerization initiator 2: di-tert-amyl peroxide; Luperox DTA produced by ARKEMAYoshitomi, Ltd.

[0168] • Thermal free radical polymerization initiator 3: 1,1-di(tert-amylperoxy)cyclohexane; Luperox 531 produced by ARKEMA Yoshitomi, Ltd.

[0169] • Thermal free radical polymerization initiator 4: α,α′-di(tert-butylperoxy)diisopropylbenzene, produced by NOFCORPORATION under the product name Perbutyl P;

[0170] • Organic free radical compound 1: 2,2,6,6-tetramethylpiperidine-1-oxy, produced by TCI;

[0171] • Organic free radical compound 2: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy, produced by TCI;

[0172] • Organic free radical compound 3: bis(2,2,6,6-tetramethyl-4-piperidinyl-1-oxy) sebacate, produced by TCI;

[0173] • Metal passivating agent: N′1,N′12-bis(2-hydroxybenzoyl)dodecanedihydrazide, ADEKASTAB CDA-6 produced by ADEKACORPORATION;

[0174] • Elastomer 1: Styrene-ethylene-butene-styrene block copolymer; Septon V9827 manufactured by Kuraray Co., Ltd.

[0175] • Elastomer 2: Styrene-ethylene-butene-styrene block copolymer; Septon 8007 manufactured by Kuraray Co., Ltd.

[0176] • Elastomer 3: Styrene-based elastomer; SE polymer produced by Denka Co., Ltd.;

[0177] • Inorganic filler: Spherical silica surface-treated with vinylsilane; Product No. 0.5μm SV-CT1 (slurry containing 25% toluene), manufactured by Admatechs;

[0178] • Flame retardants: Phosphorus-containing flame retardants; PQ-60 manufactured by DKS Co., Ltd.; and

[0179] • Antioxidant: Hindered phenolic antioxidant (pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]); AO-60 produced by ADEKA CORPORATION.

[0180] 2. Evaluation

[0181] The resin sheets were evaluated using the following methods.

[0182] (1) The temperature at which the resin sheet exhibits its lowest melt viscosity

[0183] The melt viscosity of the resin sheets was measured using a rheometer (model Rheosol G-3000, manufactured by UBM Co., Ltd.) with parallel plates over a heating range of 50°C to 250°C, under measurement conditions including a heating rate of 3°C / min and a frequency of 0.009 rad / s. The temperature at which the resin sheets exhibited the lowest melt viscosity was confirmed based on melt viscosity profiles, which illustrate the relationship between temperature and the resulting melt viscosity.

[0184] (2) Dielectric properties (relative permittivity, dielectric loss tangent and ΔDf)

[0185] Two copper foil sheets, each 18 μm thick, were arranged with their glossy surfaces facing each other, and a resin sheet was placed between the two copper foil sheets. An evaluation sample was formed by hot-pressing them at 200 °C and 2 MPa for 1 hour. This sample was then etched to remove the two copper foil sheets from both sides, yielding a test piece made from the cured resin product. The relative permittivity and dielectric loss tangent of this test piece were measured at a test frequency of 10 GHz using an IPC TM-6502.5.5.5.

[0186] Furthermore, after heating the sample at 150°C for 200 hours, the dielectric loss tangent of the sample was measured in the same manner as described above. Based on this result, the change in dielectric loss tangent due to heating (ΔDf) was obtained. It can be concluded that the smaller the value of ΔDf, the higher the stability of the dielectric loss tangent during heating.

[0187] (3) Evaluation of linear expansion coefficient and glass transition temperature

[0188] The cured product, obtained by heating a resin sheet at 200°C under vacuum for 120 minutes, was cut into 5mm × 20mm samples for evaluation. The linear expansion coefficient and glass transition temperature of this sample were measured using a thermomechanical analyzer (TMA / SS6100, manufactured by SIINanotechnology Inc.) with a 15mm clamp length, a 10g load, and a heating rate of 10°C / min until the temperature reached 350°C. Note that the coefficient of thermal expansion (α1) is the value of the linear expansion coefficient below the glass transition temperature of the cured product, and the average coefficient of thermal expansion (30-250°C) is an average calculated based on measurements taken within the range of 30°C to 250°C. If the coefficient of thermal expansion (α1) is below 40 ppm / °C, the following evaluation can be made: a reduction in the increase of the linear expansion coefficient. If the average coefficient of thermal expansion (30-250°C) is below 50 ppm / °C, the following evaluation can be made: a reduction in the increase of the linear expansion coefficient.

[0189] (4) Flame retardancy

[0190] Multiple resin sheets were stacked on top of each other to achieve a total thickness of 200 μm, and the resulting multilayer stack was heated at 200°C under vacuum for 120 minutes to obtain a cured product. This cured product was then cut to form an evaluation sample with dimensions of 125 mm × 13 mm in a planar view. The flame retardancy of this sample was measured according to UL94 standards.

[0191] [Table 1]

[0192]

[0193] [Table 2]

[0194]

[0195] [Table 3]

[0196]

[0197] [Table 4]

[0198]

[0199]

[0200] As can be seen from these results, in Examples 1 to 24, which contain free radical polymerizable unsaturated compound (A) and organic free radical compound (C), the resin sheets exhibited a higher temperature at which they reached their lowest melt viscosity than in any of Comparative Examples 1 to 4. This is advantageous for maintaining a low melt viscosity when heating the resin sheets. Furthermore, in Examples 1 to 24, low relative permittivity, low dielectric loss tangent, high dielectric loss tangent, high thermal stability, high glass transition temperature, and high flame retardancy were achieved.

Claims

1. A thermosetting resin composition, said thermosetting resin composition comprising: Free radical polymerizable unsaturated compound (A); Thermal free radical polymerization initiator (B); Organic free radical compounds (C); and Styrene-based elastomers (E), The free radical polymerizable unsaturated compound (A) comprises: a copolymer (A1) having structural units derived from monoolefins and structural units derived from dienes; and an end-group modified polyphenylene ether compound (A2). The organic free radical compound (C) contains an organic nitroxide free radical compound (C1). The content of the elastomer (E) is in the range of 5 parts by mass to 100 parts by mass relative to a total of 100 parts by mass of the copolymer (A1) having structural units derived from monoolefins and structural units derived from dienes, and the end-group modified polyphenylene ether compound (A2). The thermal free radical polymerization initiator (B) contains at least one compound selected from the group consisting of: di-tert-hexyl peroxide, di-tert-pentyl peroxide, and 1,1-di(tert-pentylperoxy)cyclohexane. The thermosetting resin composition is used to prepare the insulating layer included in a printed circuit board.

2. The thermosetting resin composition of claim 1, wherein the thermosetting resin composition further comprises a metal passivating agent (D).

3. The thermosetting resin composition of claim 1 or 2, wherein the thermosetting resin composition further comprises an inorganic filler (F).

4. The thermosetting resin composition of claim 3, wherein... The inorganic filler (F) contains silicon dioxide that has been surface-treated with a polymeric organic compound.

5. The thermosetting resin composition of claim 1 or 2, wherein the thermosetting resin composition further comprises a flame retardant (G).

6. A resin sheet comprising a dried or semi-cured product of the thermosetting resin composition according to any one of claims 1 to 5.

7. A laminate, the laminate comprising: Insulating layer and metal foil sheet, The insulating layer contains a cured product of the thermosetting resin composition according to any one of claims 1 to 5.

8. A printed circuit board, the printed circuit board comprising: Insulation layer and conductor lines, The insulating layer contains a cured product of the thermosetting resin composition according to any one of claims 1 to 5.

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