Resin composition, and prepreg, resin-coated film, resin-coated metal foil, metal-clad laminate, and wiring board each obtained using same

Abstract

One aspect of the present invention relates to a resin composition that contains an inorganic filler (B) and a resin mixture containing a thermosetting resin (A), wherein the relative dielectric constant of a cured product of the resin-containing mixture is 2.6 or less, the inorganic filler (B) contains hollow inorganic particles (B-1) having a relative dielectric constant of 1.8 or less at 10 GHz and a hollowness rate of 50-90%, the specific surface area of the hollow inorganic particles (B-1) is 30 m2 / g or less, the cumulative 50% grain diameter (D50) based on volume in the grain size distribution of the hollow inorganic particles (B-1) is 0.1-3.0 μm, and the hollow inorganic particle (B-1) content is 20-150 parts by mass per 100 parts by mass of the thermosetting resin (A).

Description

Resin composition, and prepreg, resin-coated film, resin-coated metal foil, metal-clad laminate, and wiring board using the same

[0001] The present invention relates to a resin composition, and to a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board using the same.

[0002] As the amount of information processed increases in various electronic devices, advances in packaging technologies, such as higher integration of semiconductor devices, higher density wiring, and multi-layering, are being made. Furthermore, wiring boards used in various electronic devices are required to be high-frequency compatible, such as millimeter-wave radar boards for automotive applications. To increase the signal transmission speed, wiring boards used in various electronic devices are required to reduce loss during signal transmission, and this is particularly true for high-frequency compatible wiring boards. To meet this requirement, the substrate material for forming the substrate of the wiring board used in various electronic devices is required to have a low dielectric constant and dielectric loss tangent.

[0003] Research into various thermosetting resins with low dielectric properties for use in such substrate materials is progressing. While blending inorganic fillers in addition to resin components is well known for reducing the thermal expansion coefficient and improving heat resistance, depending on the type of inorganic filler, this can hinder the low dielectric properties of the substrate material. To address this issue, a technique has been reported for reducing the dielectric constant of laminate materials by using inorganic fillers with a dielectric constant of 3.5 or less, such as hollow fillers (Patent Document 1).

[0004] However, the filler used in Patent Document 1 still has a high dielectric constant, and there is a limit to how much the dielectric constant can be reduced. Furthermore, resin compositions containing inorganic fillers can have problems with moldability (blistering, adhesion to metal foil, etc.) when molding a substrate material from the resin composition, but Patent Document 1 does not disclose any means for improving moldability.

[0005] For these reasons, there has been a demand for the development of a resin composition which, in its cured form, has excellent low dielectric properties, high heat resistance, and excellent moldability.

[0006] JP 2017-75270 A

[0007] The present invention has been made in view of the above circumstances, and aims to provide a resin composition that can achieve an extremely low dielectric constant of the cured product while maintaining heat resistance and that also has excellent moldability. It is also an object of the present invention to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that use the resin composition.

[0008] As a result of extensive investigations, the present inventors have found that the above object can be achieved by the following constitution, and have achieved the present invention through further investigations.

[0009] That is, a resin composition according to one aspect of the present invention is a resin composition comprising a resin mixture containing a thermosetting resin (A) and an inorganic filler (B), wherein the cured product of the resin-containing mixture has a relative dielectric constant of 2.6 or less, the inorganic filler (B) has a relative dielectric constant of 1.8 or less at 10 GHz, and contains hollow inorganic particles (B-1) having a hollowness of 50% or more and 90% or less, and the specific surface area of ​​the hollow inorganic particles (B-1) is 30 m ２ / g or less, the volume-based cumulative 50% particle size (D50) in the particle size distribution of the hollow inorganic particles (B-1) is 0.1 μm or more and 3.0 μm or less, and the content of the hollow inorganic particles (B-1) is 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the thermosetting resin (A).

[0010] Fig. 1 is a schematic cross-sectional view showing the configuration of a prepreg according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing the configuration of a metal-clad laminate according to one embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing the configuration of a wiring board according to one embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing the configuration of a resin-coated metal foil according to one embodiment of the present invention. Fig. 5 is a schematic cross-sectional view showing the configuration of a resin-coated film according to one embodiment of the present invention.

[0011] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to these.

[0012] <Resin Composition> A resin composition according to an embodiment of the present invention (hereinafter also simply referred to as a resin composition) contains a resin mixture containing a thermosetting resin (A) and an inorganic filler (B). The cured product of the resin-containing mixture has a relative dielectric constant of 2.6 or less. The inorganic filler (B) contains hollow inorganic particles (B-1) having a relative dielectric constant of 1.8 or less at 10 GHz and a hollowness of 50% or more and 90% or less. The specific surface area of ​​the hollow inorganic particles (B-1) is 30 m ２ / g or less, and the volume-based cumulative 50% particle size (D50) in the particle size distribution of the hollow inorganic particles (B-1) is 0.1 μm or more and 3.0 μm or less. Furthermore, the content of the hollow inorganic particles (B-1) is 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the thermosetting resin (A).

[0013] According to the above configuration, it is possible to provide a resin composition that can have an extremely low dielectric constant in the cured product while maintaining heat resistance and that also has excellent moldability. In a preferred embodiment, the resin composition of this embodiment has a dielectric constant (10 GHz) in the cured product of 2.2 or less. In this embodiment, excellent moldability means that when a substrate or the like is produced using the resin composition of this embodiment, the occurrence of blistering and the like is suppressed and adhesion to metal foil is also good.

[0014] Furthermore, by using the resin composition, it is possible to provide a prepreg, a resin-coated film, a resin-coated metal foil, a metal-clad laminate, and a wiring board that have the excellent properties.

[0015] Each component of the resin composition according to this embodiment will be specifically described below.

[0016] [Thermosetting Resin (A)] The resin composition of this embodiment includes a resin mixture containing a thermosetting resin (A). A cured product of this resin mixture has a relative dielectric constant of 2.6 or less at 10 GHz.

[0017] In this specification, the value of the dielectric constant (Dk) is a value obtained by measuring the dielectric constant at 10 GHz of a test piece prepared by the method described in the Examples below, using a cavity resonator perturbation method in accordance with ASTM D2520, at a temperature of 23±2°C and a humidity of 50±5% RH.

[0018] In a more preferred embodiment, the resin mixture has a relative dielectric constant (10 GHz) of 2.0 to 2.6 in a cured product.

[0019] The thermosetting resin (A) used in the present embodiment is a resin having thermosetting properties, and is not particularly limited as long as the dielectric constant of the cured product of the resin mixture is satisfied. However, it is preferable that the thermosetting resin (A) contains at least one selected from the group consisting of polyphenylene ether compounds, hydrocarbon compounds, epoxy compounds, maleimide compounds, phenol compounds, oxetane compounds, benzoxazine compounds, liquid crystal polymers, and compounds having a polymerizable unsaturated group.

[0020] Among these, it is more preferable to use a resin that can provide a low dielectric constant, a low dielectric loss tangent, and high heat resistance.Specific preferred examples include polyphenylene ether compounds, hydrocarbon compounds, and maleimide compounds.

[0021] (Polyphenylene Ether Compound) As the polyphenylene ether compound, for example, it is preferable to use a terminal-modified polyphenylene ether compound that can exhibit excellent low dielectric properties when cured, and it is further preferable to use a modified polyphenylene ether compound that has been terminal-modified with a substituent having a carbon-carbon unsaturated double bond.

[0022] Examples of the modified polyphenylene ether compound include modified polyphenylene ether compounds represented by any one of the following formulas (1) to (3).

[0023]

[0024]

[0025]

[0026] In the above formulas (1) to (3), R １ ~R ８ , R ９ ~R １６ and R １７ ~R ２０ are independent of each other. That is, R １ ~R ８ , R ９ ~R １６ and R １７ ~R ２０ may be the same group or different groups. １ ~R ８ , R ９ ~R １６ and R １７ ~R ２０ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, a formyl group, an alkylcarbonyl group, an alkenylcarbonyl group, or an alkynylcarbonyl group, among which a hydrogen atom and an alkyl group are preferred.

[0027] R １ ~R ８ , R ９ ~R １６ and R １７ ~R ２０ Regarding the above, specific examples of the functional groups include the following:

[0028] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 18 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0029] The alkenyl group is not particularly limited, but is preferably an alkenyl group having 2 to 18 carbon atoms, and more preferably an alkenyl group having 2 to 10 carbon atoms. Specific examples include a vinyl group, an allyl group, and a 3-butenyl group.

[0030] The alkynyl group is not particularly limited, but is preferably an alkynyl group having 2 to 18 carbon atoms, and more preferably an alkynyl group having 2 to 10 carbon atoms. Specific examples include an ethynyl group and a prop-2-yn-1-yl group (propargyl group).

[0031] The alkylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkyl group, but for example, an alkylcarbonyl group having 2 to 18 carbon atoms is preferred, and an alkylcarbonyl group having 2 to 10 carbon atoms is more preferred. Specific examples include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, and a cyclohexylcarbonyl group.

[0032] The alkenylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkenyl group, but for example, an alkenylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkenylcarbonyl group having 3 to 10 carbon atoms is more preferred. Specific examples include an acryloyl group, a methacryloyl group, and a crotonoyl group.

[0033] The alkynylcarbonyl group is not particularly limited as long as it is a carbonyl group substituted with an alkynyl group, but for example, an alkynylcarbonyl group having 3 to 18 carbon atoms is preferred, and an alkynylcarbonyl group having 3 to 10 carbon atoms is more preferred. Specific examples include a propioloyl group.

[0034] In the formulas (1) and (2), A is a structure represented by the following formula (4), and B is a structure represented by the following formula (5), as described above:

[0035]

[0036]

[0037] In formulas (4) and (5), m and n, which are repeating units, each represent an integer of 1 to 50.

[0038] R ２１ ~R ２４ and R ２５ ~R ２８are independent of each other. That is, R ２１ ~R ２４ and R ２５ ~R ２８ may be the same group or different groups. ２１ ~R ２４ and R ２５ ~R ２８ is a hydrogen atom or an alkyl group.

[0039] In the above formula (3), s represents an integer of 1 to 100.

[0040] Furthermore, in the above formula (2), Y may be a linear, branched, or cyclic hydrocarbon having 20 or less carbon atoms. More specifically, it may be, for example, a structure represented by the following formula (6):

[0041] In formula (6), R ２９ and R ３０ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include a methyl group. Examples of the group represented by formula (6) include a methylene group, a methylmethylene group, and a dimethylmethylene group.

[0042] In the above formulas (1) to (3), X １ ~X ３ For example, X each independently represents a styrene structure or a (meth)acrylate structure as represented by the following formula (7) or (8): １ and X ２ may be the same or different.

[0043]

[0044]

[0045] In formula (8), R ３１ represents a hydrogen atom or an alkyl group. The alkyl group is not particularly limited, and is preferably, for example, an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a hexyl group, and a decyl group.

[0046] The substituent X in this embodiment １ ~X ３ More specific examples of the alkyl group include vinylbenzyl groups (ethenylbenzyl groups) such as p-ethenylbenzyl and m-ethenylbenzyl groups, vinylphenyl groups, acrylate groups, and methacrylate groups.

[0047] It is believed that by using such modified polyphenylene ether compounds represented by the above formulas (1) to (3), it is possible to improve high Tg and adhesion while maintaining low dielectric properties such as low dielectric constant and low dielectric dissipation factor, and excellent heat resistance.

[0048] The modified polyphenylene ether compounds represented by the above formulas (1) to (3) can be used either alone or in combination of two or more.

[0049] In the present embodiment, the weight-average molecular weight (Mw) of the modified polyphenylene ether compound used as the thermosetting resin is not particularly limited, but is preferably, for example, 1,000 to 5,000, and more preferably 1,000 to 4,000. The weight-average molecular weight may be measured using a general molecular weight measurement method, and specific examples include values ​​measured using gel permeation chromatography (GPC). Furthermore, when the modified polyphenylene ether compound has repeating units (s, m, n) in the molecule, it is preferable that these repeating units have values ​​such that the weight-average molecular weight of the modified polyphenylene ether compound falls within the above range.

[0050] When the weight-average molecular weight of the modified polyphenylene ether compound is within this range, it exhibits the excellent low dielectric properties of the polyphenylene ether skeleton, and the cured product not only exhibits excellent heat resistance but also exhibits excellent moldability. This is believed to be due to the following reasons. Compared to ordinary polyphenylene ethers, if the weight-average molecular weight is within the above-mentioned range, the compound has a relatively low molecular weight, which tends to result in reduced heat resistance of the cured product. In this regard, the modified polyphenylene ether compound according to this embodiment has a styrene structure or a (meth)acrylate structure at its terminal, which is believed to have high reactivity and to produce a cured product with sufficiently high heat resistance. Furthermore, when the weight-average molecular weight of the modified polyphenylene ether compound is within this range, it has a high molecular weight compared to styrene or divinylbenzene, but a relatively low molecular weight compared to ordinary polyphenylene ether, which is believed to result in excellent moldability. Therefore, it is believed that such modified polyphenylene ether compounds not only exhibit excellent heat resistance of the cured product but also exhibit excellent moldability.

[0051] In the modified polyphenylene ether compound used as the thermosetting resin in this embodiment, the X １ ~X ３ The average number of substituents (number of terminal functional groups) is not particularly limited. Specifically, it is preferably 1 to 5, and more preferably 1 to 3. If the number of terminal functional groups is too small, it tends to be difficult to obtain a cured product with sufficient heat resistance. On the other hand, if the number of terminal functional groups is too large, the reactivity becomes too high, which may cause problems such as reduced shelf life and reduced fluidity of the resin composition. That is, when such modified polyphenylene ether is used, there is a risk of moldability problems such as poor molding due to insufficient fluidity, for example, the generation of voids during multilayer molding, making it difficult to obtain a highly reliable printed wiring board.

[0052] The number of terminal functional groups of a modified polyphenylene ether compound may be, for example, a numerical value representing the average number of the substituents per molecule of all modified polyphenylene ether compounds present in 1 mole of the modified polyphenylene ether compound. The number of terminal functional groups can be measured, for example, by measuring the number of hydroxyl groups remaining in the obtained modified polyphenylene ether compound and calculating the difference from the number of hydroxyl groups in the polyphenylene ether before modification. This difference from the number of hydroxyl groups in the polyphenylene ether before modification is the number of terminal functional groups. The number of hydroxyl groups remaining in the modified polyphenylene ether compound can be measured by adding a quaternary ammonium salt (tetraethylammonium hydroxide) that associates with hydroxyl groups to a solution of the modified polyphenylene ether compound and measuring the UV absorbance of the resulting mixed solution.

[0053] Furthermore, the intrinsic viscosity of the modified polyphenylene ether compound used in the present embodiment is not particularly limited. Specifically, it may be 0.03 to 0.12 dl / g, preferably 0.04 to 0.11 dl / g, and more preferably 0.06 to 0.095 dl / g. If this intrinsic viscosity is too low, the molecular weight tends to be low, and it tends to be difficult to achieve low dielectric properties such as a low dielectric constant and a low dielectric loss tangent. If the intrinsic viscosity is too high, the viscosity tends to be high, sufficient fluidity cannot be achieved, and the moldability of the cured product tends to be reduced. Therefore, if the intrinsic viscosity of the modified polyphenylene ether compound is within the above range, excellent heat resistance and moldability of the cured product can be achieved.

[0054] The intrinsic viscosity here is the intrinsic viscosity measured in methylene chloride at 25° C., and more specifically, it is the value measured, for example, with a viscometer using a 0.18 g / 45 ml methylene chloride solution (liquid temperature: 25° C.). Examples of such viscometers include the AVS500 Visco System manufactured by Schott.

[0055] In addition, the method for synthesizing the modified polyphenylene ether compound preferably used in this embodiment is a method for synthesizing the modified polyphenylene ether compound by using the above-mentioned substituent X １ ~X ３There is no particular limitation as long as a modified polyphenylene ether compound having a terminal modified by the above formula can be synthesized. Specifically, the modified polyphenylene ether compound can be synthesized by adding a substituent X １ ~X ３ and a method of reacting a compound having a halogen atom bonded thereto.

[0056] The polyphenylene ether used as a raw material is not particularly limited as long as it can ultimately synthesize a predetermined modified polyphenylene ether. Specific examples include polyphenylene ethers composed of 2,6-dimethylphenol and at least one of a bifunctional phenol and a trifunctional phenol, and those containing polyphenylene ether as a main component, such as poly(2,6-dimethyl-1,4-phenylene oxide). Furthermore, a bifunctional phenol is a phenolic compound having two phenolic hydroxyl groups per molecule, such as tetramethylbisphenol A. Furthermore, a trifunctional phenol is a phenolic compound having three phenolic hydroxyl groups per molecule.

[0057] As an example of a method for synthesizing a modified polyphenylene ether compound, for example, in the case of a modified polyphenylene ether compound represented by the above formula (2), specifically, the method comprises combining the above polyphenylene ether with a substituent X １ and X ２ and a halogen atom (substituent X １ and X ２ The compound having the substituent X is dissolved in a solvent and stirred. １ and X ２ The modified polyphenylene ether represented by the above formula (2) of this embodiment is obtained by reacting with a compound having the formula:

[0058] Furthermore, this reaction is preferably carried out in the presence of an alkali metal hydroxide. By doing so, it is believed that the reaction proceeds favorably. This is believed to be because the alkali metal hydroxide functions as a dehydrohalogenating agent, specifically, a dehydrochlorinating agent. That is, the alkali metal hydroxide eliminates hydrogen halide from the phenol group of the polyphenylene ether and the compound having the substituent X, thereby replacing the hydrogen atom of the phenol group of the polyphenylene ether with the substituent X. １ and X ２ is thought to bond to the oxygen atom of the phenol group.

[0059] The alkali metal hydroxide is not particularly limited as long as it can act as a dehalogenating agent, and examples thereof include sodium hydroxide, etc. The alkali metal hydroxide is usually used in the form of an aqueous solution, specifically, an aqueous sodium hydroxide solution.

[0060] The reaction conditions such as reaction time and reaction temperature are determined by the １ and X ２ The reaction conditions vary depending on the compound having the formula (I), and are not particularly limited as long as the reaction proceeds favorably. Specifically, the reaction temperature is preferably room temperature to 100°C, and more preferably 30 to 100°C. The reaction time is preferably 0.5 to 20 hours, and more preferably 0.5 to 10 hours.

[0061] The solvent used in the reaction is a mixture of polyphenylene ether and a compound having a substituent X １ and X ２ and a compound having a substituent X １ and X ２ There are no particular limitations on the solvent, as long as it does not inhibit the reaction with the compound having the formula (I). Specific examples include toluene.

[0062] Furthermore, the above reaction is preferably carried out in the presence of not only an alkali metal hydroxide but also a phase transfer catalyst. That is, the above reaction is preferably carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst. Doing so is believed to allow the reaction to proceed more smoothly. This is believed to be due to the following: A phase transfer catalyst has the function of incorporating an alkali metal hydroxide, is soluble in both a polar solvent phase such as water and a nonpolar solvent phase such as an organic solvent, and is capable of transferring between these phases. Specifically, when aqueous sodium hydroxide is used as the alkali metal hydroxide and an organic solvent, such as toluene, which is incompatible with water, is used as the solvent, even if the aqueous sodium hydroxide solution is added dropwise to the solvent being used for the reaction, the solvent and the aqueous sodium hydroxide solution will separate, and it is believed that the sodium hydroxide will not easily migrate to the solvent. In this case, it is believed that the aqueous sodium hydroxide solution added as the alkali metal hydroxide will not easily contribute to promoting the reaction. On the other hand, when the reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst, the alkali metal hydroxide is transferred to the solvent while being incorporated into the phase transfer catalyst, and the aqueous sodium hydroxide solution is thought to contribute more to promoting the reaction. Therefore, when the reaction is carried out in the presence of an alkali metal hydroxide and a phase transfer catalyst, the reaction is thought to proceed more smoothly.

[0063] The phase transfer catalyst is not particularly limited, but examples thereof include quaternary ammonium salts such as tetra-n-butylammonium bromide.

[0064] The resin composition according to the present embodiment preferably contains, as the modified polyphenylene ether, the modified polyphenylene ether obtained as described above.

[0065] (Hydrocarbon Compound) Preferred examples of hydrocarbon compounds that can be used in this embodiment include hydrocarbon compounds such as polyfunctional vinyl aromatic polymers, cyclic polyolefin resins, and vinyl aromatic compound-conjugated diene compound copolymers. The type of hydrocarbon compound is not particularly limited, but in consideration of moldability, appearance, and mechanical properties, it is preferable to use a hydrocarbon compound with a weight average molecular weight of 1,000 to 500,000.

[0066] The polyfunctional vinyl aromatic polymer is preferably a polymer containing at least a polyfunctional vinyl aromatic compound and / or a derivative thereof. It is not particularly limited as long as it contains a structure derived from a polyfunctional vinyl aromatic compound and / or a derivative thereof, and may be a polymer containing one or more polyfunctional vinyl aromatic compounds and / or a structure derived from a derivative thereof. The polyfunctional vinyl aromatic compound and / or a derivative thereof contains two or more vinyl groups and an aromatic ring as a monocyclic or fused ring. Examples of the polyfunctional vinyl aromatic compound and / or a derivative thereof include polymers containing compounds such as divinylbenzene, divinylnaphthalene, 9,10-divinylanthracene, 9,9-bis(4-allyloxyphenyl)fluorene, triallyl trimesate, 1,4-diisopropenylbenzene, and 1,3-diisopropenylbenzene, as well as derivatives thereof. Furthermore, the polyfunctional vinyl aromatic polymer of this embodiment may further contain a monovinyl aromatic compound or other compound polymerized therein, and may be a copolymer containing a structure derived from a monovinyl aromatic compound or other compound. The monovinyl aromatic compound contains one vinyl group and an aromatic ring as a single ring or a condensed ring, and examples thereof include styrene compounds and styrene derivatives in which some of the hydrogen atoms of the aromatic ring, such as styrene and methylstyrene, are substituted with substituents such as alkyl groups. The polyfunctional vinyl aromatic polymer may be a copolymer containing one or more structures derived from the monovinyl aromatic compound or other monomers.

[0067] The cyclic polyolefin resin used in this embodiment refers to a polyolefin-based resin having a cyclic aliphatic main chain in the main chain or side chain, or having a cyclic aliphatic hydrocarbon in the side chain. Examples of the cyclic aliphatic hydrocarbon include those containing at least one of the structures represented by the following structural formulas (9) to (17).

[0068]

[0069] The cyclic polyolefin resin includes cycloolefin copolymer (COC) type, which is obtained by copolymerizing norbornene and ethylene with a metallocene catalyst, and COP type, which is obtained by metathesis ring-opening polymerization, and can be used alone or in combination of two or more.Commercially available cyclic polyolefin resins include, for example, Zeonex (registered trademark) and Zeonor (registered trademark) manufactured by Nippon Zeon Co., Ltd., Arton (registered trademark) manufactured by JSR Corporation, Apel (registered trademark) manufactured by Mitsui Chemicals, Inc., and Topas (registered trademark) manufactured by Polyplastics Co., Ltd.

[0070] The vinyl aromatic compound-conjugated diene compound copolymer used in this embodiment is not particularly limited as long as it contains a structure derived from a vinyl aromatic compound (a compound containing one or more vinyl groups and having an aromatic ring) and a structure derived from a conjugated diene compound (a compound having a conjugated diene). Furthermore, the copolymer may contain structures derived from one or more vinyl aromatic compounds and their derivatives, or may contain a structure derived from one or more conjugated diene compounds. The vinyl aromatic compound-conjugated diene compound copolymer may be a partially hydrogenated product. Examples of the vinyl aromatic compound include styrene compounds in which some of the hydrogen atoms in the aromatic ring are substituted with alkyl groups, such as styrene, α-methylstyrene, and p-methylstyrene, and styrene derivatives such as 2-vinylnaphthalene and divinylbenzene. The conjugated diene compound is not particularly limited, but examples thereof include 1,3-butadiene, isoprene, 1,3-pentadiene, 1,4-pentadiene, 1,3-heptadiene, cyclopentadiene, 2,3-dimethyl-1,3-butadiene, 1,4-hexadiene, 1,5-hexadiene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, etc., and polymers thereof. Furthermore, in the vinyl aromatic compound-conjugated diene compound copolymer, the content of structural units derived from the vinyl aromatic compound is preferably 5 to 95% by mass, more preferably 10 to 80% by mass, and even more preferably 20 to 50% by mass.

[0071] (Maleimide Compound) The maleimide compound that can be used in this embodiment is not particularly limited as long as it has a maleimide group in the molecule. Specific examples of the maleimide compound include monofunctional maleimide compounds having one maleimide group in the molecule, polyfunctional maleimide compounds having two or more maleimide groups in the molecule, and modified maleimide compounds. Examples of the modified maleimide compound include modified maleimide compounds in which a portion of the molecule is modified with an amine compound, modified maleimide compounds in which a portion of the molecule is modified with a silicone compound, and modified maleimide compounds in which a portion of the molecule is modified with an amine compound and a silicone compound.

[0072] (Other Thermosetting Resins) In addition to the above, the resin composition of this embodiment can also use, as the thermosetting resin (A), thermosetting resins other than the above-mentioned thermosetting resins (hereinafter also referred to as "other thermosetting resins"). Examples include phenolic compounds, benzoxazine compounds, liquid crystal polymers, styrene, styrene derivatives, compounds having an acryloyl group in the molecule, compounds having a methacryloyl group in the molecule, compounds having a vinyl group in the molecule, compounds having an allyl group in the molecule, compounds having an acenaphthylene structure in the molecule, and isocyanurate compounds having an isocyanurate group in the molecule. These can be used alone or in combination with the above-mentioned thermosetting resins.

[0073] Examples of the styrene derivatives include bromostyrene and dibromostyrene.

[0074] The compound having an acryloyl group in the molecule is an acrylate compound. Examples of the acrylate compound include a monofunctional acrylate compound having one acryloyl group in the molecule and a polyfunctional acrylate compound having two or more acryloyl groups in the molecule. Examples of the monofunctional acrylate compound include methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate. Examples of the polyfunctional acrylate compound include tricyclodecane dimethanol diacrylate.

[0075] The compound having a methacryloyl group in the molecule is a methacrylate compound. Examples of the methacrylate compound include a monofunctional methacrylate compound having one methacryloyl group in the molecule and a polyfunctional methacrylate compound having two or more methacryloyl groups in the molecule. Examples of the monofunctional methacrylate compound include methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate. Examples of the polyfunctional methacrylate compound include tricyclodecane dimethanol dimethacrylate.

[0076] The compound having a vinyl group in the molecule is a vinyl compound. Examples of the vinyl compound include a monofunctional vinyl compound (monovinyl compound) having one vinyl group in the molecule, and a polyfunctional vinyl compound having two or more vinyl groups in the molecule. Examples of the polyfunctional vinyl compound include divinylbenzene, divinylnaphthalene, and polybutadiene.

[0077] The compound having an allyl group in the molecule is an allyl compound. Examples of the allyl compound include a monofunctional allyl compound having one allyl group in the molecule and a polyfunctional allyl compound having two or more allyl groups in the molecule. Examples of the polyfunctional allyl compound include diallyl phthalate (DAP).

[0078] The compound having an acenaphthylene structure in the molecule is an acenaphthylene compound. Examples of the acenaphthylene compound include acenaphthylene, alkylacenaphthylenes, halogenated acenaphthylenes, and phenylacenaphthylenes. Examples of the alkylacenaphthylenes include 1-methylacenaphthylene, 3-methylacenaphthylene, 4-methylacenaphthylene, 5-methylacenaphthylene, 1-ethylacenaphthylene, 3-ethylacenaphthylene, 4-ethylacenaphthylene, and 5-ethylacenaphthylene. Examples of the halogenated acenaphthylenes include 1-chloroacenaphthylene, 3-chloroacenaphthylene, 4-chloroacenaphthylene, 5-chloroacenaphthylene, 1-bromoacenaphthylene, 3-bromoacenaphthylene, 4-bromoacenaphthylene, and 5-bromoacenaphthylene. Examples of the phenylacenaphthylenes include 1-phenylacenaphthylene, 3-phenylacenaphthylene, 4-phenylacenaphthylene, and 5-phenylacenaphthylene. The acenaphthylene compound may be a monofunctional acenaphthylene compound having one acenaphthylene structure in the molecule, as described above, or a polyfunctional acenaphthylene compound having two or more acenaphthylene structures in the molecule.

[0079] The compound having an isocyanurate group in the molecule is an isocyanurate compound. Examples of the isocyanurate compound include compounds further having an alkenyl group in the molecule (alkenyl isocyanurate compounds), such as triallyl isocyanurate (TAIC).

[0080] Among the above, for example, polyfunctional acrylate compounds having two or more acryloyl groups in the molecule, polyfunctional methacrylate compounds having two or more methacryloyl groups in the molecule, polyfunctional vinyl compounds having two or more vinyl groups in the molecule, styrene derivatives, allyl compounds having an allyl group in the molecule, maleimide compounds having a maleimide group in the molecule, acenaphthylene compounds having an acenaphthylene structure in the molecule, and isocyanurate compounds having an isocyanurate group in the molecule are preferred.

[0081] The above-mentioned other thermosetting resins may be used alone or in combination of two or more kinds.

[0082] The weight-average molecular weight of the other thermosetting resin is preferably 100 to 5000, more preferably 100 to 4000, and even more preferably 100 to 3000. If the weight-average molecular weight is too low, the resin composition may be easily volatilized from its component system. Furthermore, if the weight-average molecular weight is too high, the viscosity of the resin composition varnish or the melt viscosity during heat molding may be too high. Therefore, when the weight-average molecular weight of the other thermosetting resin is within this range, a resin composition with superior heat resistance of the cured product can be obtained. The weight-average molecular weight may be measured using a general molecular weight measurement method, and specific examples include values ​​measured using gel permeation chromatography (GPC).

[0083] (Content / Ratio) The above-described thermosetting resin (A) is preferably contained in an amount of, for example, 10 to 70 mass % relative to the total solid content of the resin composition, and more preferably 10 to 50 mass %.

[0084] Although not particularly limited, the resin composition of the present embodiment preferably contains, as the thermosetting resin (A), at least one low dielectric resin selected from polyphenylene ether compounds, hydrocarbon compounds, and maleimide compounds.

[0085] When a polyphenylene ether compound is included, it is preferably included in an amount of 10 to 90 parts by mass, more preferably 30 to 90 parts by mass, per 100 parts by mass of the thermosetting resin. When a hydrocarbon compound is included, it is preferably included in an amount of 10 to 90 parts by mass, more preferably 30 to 90 parts by mass, per 100 parts by mass of the thermosetting resin. When a maleimide compound is included, it is preferably included in an amount of 10 to 90 parts by mass, more preferably 10 to 70 parts by mass, per 100 parts by mass of the thermosetting resin.

[0086] In addition to the low dielectric resin, the thermosetting resin (A) further contains at least one other thermosetting resin selected from the group consisting of a phenol compound, an oxetane compound, a benzoxazine compound, a liquid crystal polymer, a compound having a polymerizable unsaturated group, styrene, a styrene derivative, a compound having an acryloyl group in the molecule, a compound having a methacryloyl group in the molecule, a compound having a vinyl group in the molecule, a compound having an allyl group in the molecule, a compound having an acenaphthylene structure in the molecule, and an isocyanurate compound having an isocyanurate group in the molecule. In this case, it is preferable that one or more of these compounds are contained in an amount of 10 to 90 parts by mass per 100 parts by mass of the low dielectric resin.

[0087] (Other Additives, etc.) The resin mixture contained in the resin composition of this embodiment may contain various additives in addition to the thermosetting resin (A) described above. Examples of the additives include elastomers, flame retardants, antifoaming agents such as silicone-based antifoaming agents and acrylate-based antifoaming agents, antioxidants, heat stabilizers, antistatic agents, UV absorbers, dyes and pigments, lubricants, dispersants such as wetting and dispersing agents, and coupling agents.

[0088] The resin composition according to this embodiment may further contain a reaction initiator and / or a curing accelerator. While the curing reaction can proceed with the resin component alone, depending on the process conditions, it may be difficult to raise the temperature high enough for curing to proceed. Therefore, a reaction initiator and / or a curing accelerator may be added. The reaction initiator and curing accelerator are not particularly limited as long as they can accelerate the curing reaction of the thermosetting resin as described above. Specific examples include metal oxides, azo compounds, peroxides, imidazole compounds, phosphorus-based curing accelerators, and amine-based curing accelerators. These may be used alone or in combination of two or more. The reaction initiator and curing accelerator are preferably added in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the total resin components.

[0089] [Inorganic Filler (B)] The resin composition of the present embodiment contains an inorganic filler (B). The inorganic filler (B) contains hollow inorganic particles (B-1) having a relative dielectric constant of 1.8 or less at 10 GHz and a hollowness of 50% or more and 90% or less.

[0090] (Hollow Inorganic Particles (B-1)) The hollow inorganic particles (B-1) used in this embodiment have a relative dielectric constant of 1.8 or less at 10 GHz and a hollow fraction of 50% or more and 90% or less. The relative dielectric constant of the hollow inorganic particles (B-1) is a value measured by the same method as described above. In this specification, the "hollow fraction" is a value calculated from the specific gravity of the hollow inorganic particles (B-1) and the specific gravity of inorganic particles of the same type as the hollow inorganic particles but which are solid (without voids) rather than hollow. For example, in the case of silica particles, since the specific gravity of solid silica particles is 2.2, the hollow fraction is a value calculated by the following formula: hollow fraction = (1 - specific gravity of hollow silica particles / 2.2) × 100.

[0091] By including the hollow inorganic particles (B-1) having a relative dielectric constant and hollowness within the above ranges, the resin composition of the present embodiment can have excellent low dielectric properties in the cured product thereof.

[0092] The specific surface area of ​​the hollow inorganic particles (B-1) is 30 m ２ / g or less. In this specification, the specific surface area refers to the specific surface area measured by the BET method, and means a value measured by the method shown in the Examples described later. By containing hollow inorganic particles (B-1) having a specific surface area in the above range, the resin composition of this embodiment has excellent moldability.

[0093] Furthermore, the volume-based cumulative 50% particle size (D50) in the particle size distribution of the hollow inorganic particles (B-1) is 0.1 μm or more and 3.0 μm or less. In this specification, the particle size distribution is a value measured by particle size distribution measurement using the Coulter Counter method, and can be measured, for example, using a Coulter Counter particle size distribution measuring device "LS13 320" (manufactured by Beckman Coulter, Inc.) used in the examples described below. The inclusion of hollow inorganic particles (B-1) having a D50 in the above range has the advantage of improving the processability of substrates and the like formed using the resin composition of this embodiment.

[0094] The resin composition of this embodiment contains hollow inorganic particles (B-1) satisfying the above-mentioned hollow ratio, dielectric constant, specific surface area, and D50 in an amount of 20 to 150 parts by mass per 100 parts by mass of the above-mentioned thermosetting resin (A), thereby providing a resin composition in which the cured product has heat resistance and low dielectric properties (dielectric constant of 2.2 or less) and excellent moldability. A more preferred amount of hollow inorganic particles (B-1) in the resin composition is 35 to 100 parts by mass per 100 parts by mass of the above-mentioned thermosetting resin (A).

[0095] The relative dielectric constant of the hollow inorganic particles (B-1) is more preferably in the range of 1.4 to 1.8, and even more preferably in the range of 1.4 to 1.6. The void ratio is preferably 60% or more and 80% or less, and even more preferably 70% or more and 80% or less. The specific surface area is more preferably in the range of 5 m ２ / g or more 20m ２ / g or less. Furthermore, the D50 is more preferably in the range of 0.5 μm or more and 2.0 μm or less.

[0096] In addition to the above, it is more preferable that the Na+ ion concentration in the extracted water obtained by mixing 1 g of hollow inorganic particles (B-1) with 20 g of pure water and heating at 121°C for 24 hours is less than 20 μg / g. If the ion concentration exceeds that level, ion migration is likely to occur when a voltage is applied to the substrate material in a high humidity environment, which may adversely affect the electrical insulation reliability of the substrate material. Furthermore, pure water means water with a conductivity of 0.06 μS / cm at 25°C. The Na+ ion concentration in the extracted water is less than 20 μg / g. ＋ The ion concentration is more preferably 10 μg / g or less, and although there is no particular limitation on the lower limit, it is usually about 0.1 μg / g or more from the viewpoint of the detection limit.

[0097] Furthermore, it is preferable that the Cl- ion concentration in the extracted water is less than 20 μg / g. This is thought to further improve the moisture resistance reliability described above. The Cl- ion concentration in the extracted water is more preferably 10 μg / g or less, and although there is no particular limitation on the lower limit, it is usually about 0.1 μg / g or more from the viewpoint of the detection limit.

[0098] The content of the hollow inorganic particles (B-1) is preferably 50 to 100 mass %, and more preferably 80 to 100 mass %, based on the total amount of the inorganic filler (B). That is, the inorganic filler (B) of this embodiment may be composed only of the hollow inorganic particles (B-1), or may contain another inorganic filler (B-2).

[0099] Specific examples of such hollow inorganic particles (B-1) include hollow silica particles, hollow alumina particles, hollow titania particles, etc. Among these, hollow silica particles are preferred from the viewpoint of low dielectric constant.

[0100] The hollow silica particles used in this embodiment are not particularly limited as long as they satisfy the above-mentioned requirements and can be used as an inorganic filler. Commercially available hollow silica particles can also be used, such as "HS-200" and "HS-70" manufactured by AGC Si-Tech Co., Ltd.

[0101] The hollow inorganic particles (B-1) may be composed of only hollow silica particles, or may contain other hollow inorganic particles. The proportion of hollow silica particles in the hollow inorganic particles (B-1) is preferably 3 to 100 mass %, more preferably 50 to 100 mass %, based on the total amount of the hollow inorganic particles (B-1).

[0102] (Other Inorganic Particles (B-2)) The resin composition of the present embodiment may contain inorganic particles (B-2) other than the hollow inorganic particles (B-1), as long as the effects of the present invention are not impaired. The inorganic particles (B-2) are not particularly limited as long as they can be used as an inorganic filler contained in the resin composition. Specific examples include metal oxide particles such as solid silica particles, alumina particles, titanium oxide particles, magnesium oxide particles, and mica particles, metal hydroxide particles such as aluminum hydroxide particles and magnesium hydroxide particles, talc particles, aluminum borate particles, barium sulfate particles, aluminum nitride particles, silicon nitride particles, magnesium carbonate particles such as anhydrous magnesium carbonate particles, boron nitride particles, calcium carbonate particles, and the like. Among these, anhydrous magnesium carbonate particles, alumina particles, and silicon nitride particles are preferred.

[0103] The content of the inorganic particles (B-2) is preferably 0 to 50 parts by mass, more preferably 0 to 20 parts by mass, per 100 parts by mass of the total amount of the inorganic filler (B).

[0104] <Prepreg, Resin-Coated Film, Metal-Clad Laminate, Wiring Board, and Resin-Coated Metal Foil> Next, a prepreg for wiring boards, a metal-clad laminate, a wiring board, and a resin-coated metal foil using the resin composition of this embodiment will be described.

[0105] 1 is a schematic cross-sectional view showing an example of a prepreg 1 according to an embodiment of the present invention. In the following description, the respective reference numerals represent: 1 prepreg, 2 resin composition or semi-cured resin composition, 3 fibrous substrate, 11 metal-clad laminate, 12 insulating layer, 13 metal foil, 14 wiring, 21 wiring board, 31 resin-coated metal foil, 32, 42 resin layer, 41 resin-coated film, and 43 support film.

[0106] As shown in Fig. 1 , the prepreg 1 according to this embodiment comprises the resin composition or a semi-cured product of the resin composition 2, and a fibrous base material 3. Examples of this prepreg 1 include those in which the fibrous base material 3 is present in the resin composition or a semi-cured product thereof 2. That is, this prepreg 1 comprises the resin composition or a semi-cured product thereof, and the fibrous base material 3 present in the resin composition or a semi-cured product thereof 2.

[0107] In this embodiment, the term "semi-cured product" refers to a resin composition that has been partially cured to the extent that it can be further cured. That is, the semi-cured product is a resin composition that has been semi-cured (B-staged). For example, when a resin composition is heated, the viscosity initially gradually decreases, and then curing begins, and the viscosity gradually increases. In such a case, the semi-cured state can be exemplified by the state between when the viscosity starts to increase and when the composition is completely cured.

[0108] The prepreg obtained using the resin composition according to this embodiment may comprise a semi-cured product of the resin composition as described above, or may comprise the uncured resin composition itself. That is, it may be a prepreg comprising a semi-cured product of the resin composition (the resin composition in B stage) and a fibrous substrate, or a prepreg comprising the resin composition before curing (the resin composition in A stage) and a fibrous substrate. Specific examples include those in which a fibrous substrate is present in the resin composition. The resin composition or its semi-cured product may be obtained by heating and drying the resin composition.

[0109] The resin composition according to the present embodiment is often prepared in the form of a varnish and used as a resin varnish when producing the prepreg, or the resin-coated metal foil or metal-clad laminate described below. Such a resin varnish is prepared, for example, as follows.

[0110] First, components that are soluble in organic solvents, such as a thermosetting resin and a reaction initiator, are added to an organic solvent and dissolved. Heating may be performed as necessary. Then, components that are insoluble in organic solvents, such as inorganic fillers, are added, and the mixture is dispersed to a predetermined dispersed state using a homodisper, a planetary mixer, a roll mill, a jet mill, or the like, as necessary, to prepare a varnish-like resin composition. The organic solvent used here is not particularly limited as long as it dissolves the thermosetting resin and the like and does not inhibit the curing reaction. Specific examples include toluene, methyl ethyl ketone, cyclohexanone, and propylene glycol monomethyl ether acetate. These may be used alone or in combination of two or more.

[0111] As a method for producing the prepreg 1 of this embodiment using the varnish-like resin composition of this embodiment, for example, a method of impregnating the fibrous base material 3 with the resin composition 2 in the form of a resin varnish and then drying it can be mentioned.

[0112] Specific examples of fibrous substrates used in producing prepregs include glass cloth, aramid cloth, polyester cloth, LCP (liquid crystal polymer) nonwoven fabric, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper. The use of glass cloth results in a laminate with excellent mechanical strength, and flattened glass cloth is particularly preferred. The glass cloth used in this embodiment is not particularly limited, but examples include low-dielectric-constant glass cloths such as E glass, S glass, NE glass, Q glass, L glass, and L2 glass. Flattening can be performed, for example, by continuously pressing the glass cloth with a press roll at an appropriate pressure to compress the yarns flat. The thickness of the fibrous substrate can generally be, for example, 0.01 to 0.3 mm.

[0113] The resin varnish (resin composition 2) is impregnated into the fibrous substrate 3 by immersion, coating, or the like. This impregnation can be repeated multiple times as necessary. In this case, it is also possible to repeat the impregnation using multiple resin varnishes with different compositions and concentrations, and to adjust the final composition (content ratio) and resin amount to the desired one.

[0114] The fibrous substrate 3 impregnated with the resin varnish (resin composition 2) is heated under desired heating conditions, for example, at a temperature of 80°C or higher and 180°C or lower for 1 minute or longer and 10 minutes or shorter. By heating, the solvent is volatilized from the varnish, reducing or removing the solvent, thereby obtaining a prepreg 1 in an uncured (A-stage) or semi-cured (B-stage) state.

[0115] 4, the resin-coated metal foil 31 of this embodiment has a configuration in which a resin layer 32 containing the above-mentioned resin composition or a semi-cured product of the resin composition is laminated with a metal foil 13. That is, the resin-coated metal foil of this embodiment may be a resin-coated metal foil comprising a resin layer containing the resin composition before curing (the resin composition in A stage) and a metal foil, or a resin-coated metal foil comprising a resin layer containing a semi-cured product of the resin composition (the resin composition in B stage) and a metal foil.

[0116] Examples of a method for producing such a resin-coated metal foil 31 include a method in which the resin composition in the form of a resin varnish as described above is applied to the surface of a metal foil 13 such as a copper foil, followed by drying. Examples of the application method include a bar coater, a comma coater, a die coater, a roll coater, a gravure coater, and the like.

[0117] As the metal foil 13, any metal foil that is used in metal-clad laminates, wiring boards, etc. can be used without any limitation, and examples thereof include copper foil and aluminum foil.

[0118] 5, the resin-coated film 41 of this embodiment has a configuration in which a resin layer 42 containing the above-mentioned resin composition or a semi-cured product of the resin composition is laminated on a film support substrate 43. That is, the resin-coated film of this embodiment may be a resin-coated film comprising the resin composition before curing (the resin composition in A stage) and a film support substrate, or may be a resin-coated film comprising a semi-cured product of the resin composition (the resin composition in B stage) and a film support substrate.

[0119] A method for producing such a resin-coated film 41 includes, for example, applying a resin varnish-like resin composition as described above to the surface of the film support substrate 43, and then evaporating the solvent from the varnish to reduce or remove the solvent, thereby obtaining a resin-coated film in a pre-cured (A stage) or semi-cured (B stage) state.

[0120] Examples of the film support substrate include electrically insulating films such as polyimide films, PET (polyethylene terephthalate) films, polyester films, polyparabanic acid films, polyether ether ketone films, polyphenylene sulfide films, aramid films, polycarbonate films, and polyarylate films.

[0121] In the resin-coated film and resin-coated metal foil of this embodiment, the resin composition or a semi-cured product thereof may be obtained by drying or heat-drying the resin composition, as in the case of the prepreg described above.

[0122] The thickness of the metal foil 13 and the film support substrate 43 can be appropriately set depending on the desired purpose. For example, a metal foil 13 having a thickness of approximately 0.2 to 70 μm can be used. When the thickness of the metal foil is, for example, 10 μm or less, a carrier-attached copper foil having a release layer and a carrier for improved handling may be used. The resin varnish is applied to the metal foil 13 and the film support substrate 43 by coating, which can be repeated multiple times as needed. In addition, it is also possible to repeatedly apply multiple resin varnishes with different compositions and concentrations to adjust the final composition (content ratio) and resin amount to the desired level.

[0123] The drying or heating and drying conditions in the manufacturing method of the resin-coated metal foil 31 or the resin-coated film 41 are not particularly limited, but after applying a resin varnish-like resin composition to the metal foil 13 or the film support substrate 43, it is heated under the desired heating conditions, for example, at 80 to 170°C for about 1 to 10 minutes, to volatilize the solvent from the varnish and reduce or remove the solvent, thereby obtaining the resin-coated metal foil 31 or the resin-coated film 41 in a pre-cured (A stage) or semi-cured (B stage) state.

[0124] The resin-coated metal foil 31 or the resin-coated film 41 may be provided with a cover film or the like, as necessary. The provision of a cover film can prevent the inclusion of foreign matter, etc. The cover film is not particularly limited as long as it can be peeled off without damaging the shape of the resin composition. For example, a polyolefin film, a polyester film, a TPX film, a film formed by providing a release agent layer on any of these films, or even paper formed by laminating any of these films onto a paper substrate can be used.

[0125] 2, the metal-clad laminate 11 of this embodiment is characterized by having an insulating layer 12 containing a cured product of the above-described resin composition or a cured product of the above-described prepreg, and a metal foil 13. Note that the metal foil 13 used in the metal-clad laminate 11 may be the same as the metal foil 13 described above.

[0126] The metal-clad laminate 11 of this embodiment can also be produced using the resin-coated metal foil 31 or resin-coated film 41 described above.

[0127] A method for producing a metal-clad laminate using the prepreg 1, resin-coated metal foil 31, or resin-coated film 41 obtained as described above involves stacking one or more prepregs 1, resin-coated metal foils 31, or resin-coated films 41, and then stacking a metal foil 13 such as copper foil on both sides or one side of the prepreg 1, and then heat-pressure molding the stack to form an integrated laminate, thereby producing a double-sided or single-sided metal foil-clad laminate. The heat-pressure conditions can be appropriately set depending on the thickness of the laminate to be produced, the type of resin composition, and the like, but can be, for example, a temperature of 170 to 220°C, a pressure of 1.5 to 5.0 MPa, and a time of 60 to 150 minutes.

[0128] Alternatively, the metal-clad laminate 11 may be produced by forming a film-like resin composition on the metal foil 13 and then applying heat and pressure, without using the prepreg 1 or the like.

[0129] As shown in FIG. 3, the wiring board 21 of this embodiment has an insulating layer 12 containing the cured product of the resin composition or the cured product of the prepreg, and wiring 14 .

[0130] The resin composition of this embodiment is suitable for use as a material for an interlayer insulating layer of a wiring board. For example, a wiring board 21 can be produced by etching the metal foil 13 on the surface of the metal-clad laminate 11 obtained above to form a circuit (wiring), thereby obtaining a wiring board 21 having a conductor pattern (wiring 14) as a circuit on the surface of the laminate. In addition to the above-described methods, examples of the circuit formation method include circuit formation by a semi-additive process (SAP) or a modified semi-additive process (MSAP).

[0131] The prepreg, resin-coated film, and resin-coated metal foil obtained using the resin composition of this embodiment have excellent low dielectric properties and heat resistance in the cured product, and also have excellent formability, making them very useful for industrial applications. In addition, the metal-clad laminates and wiring boards obtained by curing them have high heat resistance and excellent low dielectric properties.

[0132] This specification discloses various aspects of the technology as described above, but the main technologies among them are summarized below.

[0133] A resin composition according to a first aspect of the present invention is a resin composition comprising a resin mixture containing a thermosetting resin (A) and an inorganic filler (B), wherein the cured product of the resin-containing mixture has a relative dielectric constant of 2.6 or less, the inorganic filler (B) has a relative dielectric constant of 1.8 or less at 10 GHz, and contains hollow inorganic particles (B-1) having a hollow ratio of 50% or more and 90% or less, and the specific surface area of ​​the hollow inorganic particles (B-1) is 30 m ２ / g or less, the volume-based cumulative 50% particle size (D50) in the particle size distribution of the hollow inorganic particles (B-1) is 0.1 μm or more and 3.0 μm or less, and the content of the hollow inorganic particles (B-1) is 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the thermosetting resin (A).

[0134] A resin composition according to a second aspect of the present invention is the resin composition according to the first aspect, wherein the hollow inorganic particles (B-1) contain hollow silica particles.

[0135] The resin composition according to a third aspect of the present invention is the resin composition according to the first or second aspect, wherein the inorganic filler (B) contains inorganic particles (B-2) different from the hollow inorganic particles (B-1).

[0136] A resin composition according to a fourth aspect of the present invention is the resin composition according to any one of the first to third aspects, wherein the thermosetting resin (A) contains at least one selected from the group consisting of polyphenylene ether compounds, hydrocarbon compounds, epoxy compounds, maleimide compounds, phenolic compounds, oxetane compounds, benzoxazine compounds, liquid crystal polymers, and compounds having a polymerizable unsaturated group.

[0137] A resin composition according to a fifth aspect of the present invention is the resin composition according to any one of the first to fourth aspects, wherein a cured product of the resin composition has a relative dielectric constant of 2.2 or less at 10 GHz.

[0138] A prepreg according to a sixth aspect of the present invention comprises the resin composition of any one of the first to fifth aspects or a semi-cured product of the resin composition, and a fibrous base material.

[0139] A resin-coated film according to a seventh aspect of the present invention comprises a resin layer containing the resin composition of any one of the first to fifth aspects or a semi-cured product of the resin composition, and a support film.

[0140] A resin-coated metal foil according to an eighth aspect of the present invention comprises a resin layer containing the resin composition of any one of the first to fifth aspects or a semi-cured product of the resin composition, and a metal foil.

[0141] A metal-clad laminate according to a ninth aspect of the present invention has an insulating layer containing a cured product of the resin composition of any one of the first to fifth aspects or a cured product of the prepreg of the sixth aspect, and a metal foil.

[0142] A wiring board according to a tenth aspect of the present invention has an insulating layer containing a cured product of the resin composition of any one of the first to fifth aspects or a cured product of the prepreg of the sixth aspect, and wiring.

[0143] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0144] First, the components used in preparing the resin composition in this example will be described.

[0145] <Thermosetting resin (A)> PPE: polyphenylene ether compound having a methacryloyl group at its terminal ("SA9000" manufactured by SABIC Innovative Plastics, weight average molecular weight Mw 2000, number of terminal functional groups 2) TAIC: triallyl isocyanurate (manufactured by Mitsubishi Chemical Corporation) Epoxy compound: dicyclopentadiene type epoxy resin ("HP-7200H-75M" manufactured by DIC Corporation, epoxy equivalent 280) Phenol compound: novolac type phenolic resin ("TD-2090-60M" manufactured by DIC Corporation, hydroxyl group equivalent 105)

[0146] <Inorganic Filler (B)> (Hollow Inorganic Particles (B-1)) Hollow Silica Particles 1: "HS-200" manufactured by AGC Si-Tech Co., Ltd. (relative dielectric constant at 10 GHz: 1.5, hollowness: 78%, specific gravity: 0.48, BET specific surface area: 12 m) ２ / g, D50: 2 μm) Hollow silica particles 2: "HS-070" manufactured by AGC Si-Tech Co., Ltd. (relative dielectric constant at 10 GHz: 1.7, hollowness: 69%, specific gravity: 0.69, BET specific surface area: 17 m ２ / g, D50: 0.5 μm) Hollow silica particles 3: manufactured by Admatechs Co., Ltd. (relative dielectric constant at 10 GHz: 2.8, hollowness: 38%, specific gravity: 1.4, BET specific surface area: 12 m ２ / g, D50: 0.6 μm) (Other inorganic particles (B-2)) Hollow silica 4: "iM16K" manufactured by 3M Japan Co., Ltd. (relative dielectric constant at 10 GHz: 1.5, hollowness: 80%, specific gravity: 0.46, BET specific surface area: 1.5 m ２ / g, D50: 20 μm) Solid silica particles: spherical silica "SO-C6" manufactured by Admatechs Co., Ltd. (relative dielectric constant at 10 GHz: 3.7, hollowness: none, specific gravity: 2.2, BET specific surface area: 2 m ２ / g, D50: 2μm)

[0147] <Other components> (Reaction initiator) Peroxide: 1,3-bis(butylperoxyisopropyl)benzene ("Perbutyl P" manufactured by NOF Corporation) (Curing accelerator) Imidazole curing accelerator: 2-ethyl-4-methylimidazole ("2E4MZ" manufactured by Shikoku Chemicals Corporation)

[0148] Examples 1 to 5 and Comparative Examples 1 to 5 [Preparation Method] (Resin Varnish) Each component was added to an organic solvent (toluene) in the blending ratio (parts by mass, solid content) shown in Table 1 so that the solid content concentration of the resin composition was 60 to 75 mass%, and the mixture was mixed and dispersed in a planetary centrifugal mixer at 2000 RPM for about 3 minutes, thereby obtaining a varnish-like resin composition (resin varnish) for each of the Examples and Comparative Examples.

[0149] (Resin Coated Copper Foil) Resin coated copper foil (RCC) was prepared using the resin varnishes of the respective Examples and Comparative Examples prepared above, and was used for the following evaluations.

[0150] For the RCC, a copper foil with a thickness of 18 μm (FV-WS manufactured by Furukawa Electric Co., Ltd.) was used. The resin varnish was applied to the surface of the copper foil so that the thickness after drying was 50 μm, and this was heated and dried at 120° C. for 3 minutes until it was in a semi-cured state, thereby obtaining an RCC.

[0151] (Metal-clad laminate) Two RCCs obtained above were bonded together and heated and pressed for 120 minutes under vacuum conditions at a temperature of 200°C and a pressure of 1 to 4 MPa to obtain a copper-clad laminate (CCL) (evaluation substrate) having a thickness of 140 μm and copper foil bonded to both sides.

[0152] <Evaluation Tests> (Physical Properties of Inorganic Filler) The physical properties of the inorganic filler described above were determined as follows. Hollowness Since all hollow inorganic particles used in this example were hollow silica particles, the hollowness of the hollow inorganic particles was determined from the specific gravity of each hollow silica particle and the specific gravity of solid silica (2.2) using the following formula: Hollowness = (1 - specific gravity of hollow silica particle / 2.2) x 100

[0153] Specific Surface Area The specific surface area of ​​each inorganic filler was measured by the BET method using a fully automatic gas adsorption measurement device "autosorb-iQ" (manufactured by Anton Paar Japan Co., Ltd.).

[0154] Particle Size Distribution of Inorganic Filler The particle size distribution (D50) of the inorganic filler in each of the Examples and Comparative Examples was determined by measurement using a Coulter Counter-type particle size distribution measuring device "LS13 320" (manufactured by Beckman Coulter, Inc.).

[0155] (Substrate formability) The laminates (CCL) prepared above were visually evaluated according to the following criteria (sample shape: 50 mm length x 50 mm width, number of samples (n) = 3). Good: No blistering, good adhesion, thickness change of ±20 μm or less. Fair: No blistering, good adhesion, thickness change of more than 20 μm. Unacceptable: Blisters or peeling from copper foil.

[0156] (Oven Heat Resistance) Heat resistance was evaluated in accordance with JIS C 6481 (1996). The copper-clad laminates cut to a predetermined size (50 mm length × 50 mm width) were left in a thermostatic chamber set to 280°C for 1 hour and then removed. The test pieces heat-treated at each temperature were visually observed, and the test pieces were evaluated as pass if no blisters occurred and fail if blisters occurred.

[0157] (Dielectric Properties: Dielectric Constant (Dk)) In each Example and Comparative Example, a resin mixture containing a thermosetting resin (without inorganic filler) was prepared at the blending ratio (parts by mass, solids content) shown in Table 1. Specifically, toluene and the resin components were mixed and dispersed to a solids concentration of 60-75%, resulting in a resin varnish without inorganic filler. Each resulting resin varnish was impregnated into a fibrous substrate (glass cloth "#1078 L Glass" manufactured by Asahi Kasei Corporation) and dried in a dryer at 120°C for 3 minutes to obtain a prepreg without inorganic filler. The prepreg was placed in a sealed plastic bag and kneaded to remove the powder, obtaining a resin mixture powder. The resulting resin mixture powder was placed in a frame measuring 80 mm long x 80 mm wide x 0.3 mm thick and cured under reduced pressure at 220°C and a pressure of 0.3 MPa for 120 minutes to prepare a cured resin test specimen (size: 50 mm long x 2 mm wide x 0.3 mm thick). The relative dielectric constant (Dk) of the test piece was then measured by a cavity resonator perturbation method.

[0158] In addition, the copper foil was removed from the copper-clad laminate (CCL) to prepare a test specimen (50 mm long x 2 mm wide), and the dielectric constant (Dk) of the test specimen was also measured by the cavity resonator perturbation method. Specifically, a network analyzer (N5230A manufactured by Agilent Technologies) was used to measure the dielectric constant (Dk) of each test specimen at 10 GHz. A CCL with a dielectric constant of 2.2 or less was considered acceptable.

[0159] (Ion impurities (Na ＋ Measurement of )) First, as a pretreatment, resin pieces of each Example and Comparative Example were washed with pure water for 20 minutes and then prepared into powder of 100 mesh under and 200 mesh up. The powder was then washed with pure water and isopropyl alcohol (IPA) and dried. Next, the obtained sample was placed in a Teflon (registered trademark) container, and pure water was added in a ratio of about 20 g per 1 g of sample. The liquid extracted at 121 °C for 24 hours was used as the measurement sample.

[0160] Next, each sample was subjected to ion chromatography analysis. Specifically, the Na content of each sample was measured using an analyzer: Dionex Integration HPIC (manufactured by Thermo Fisher). ＋ In this test, the amount of Na ＋ Amounts of less than 20 μg / g were judged as pass, and amounts of 20 μg / g or more were judged as fail.

[0161] The results are shown in Table 1.

[0162]

[0163] (Discussion) As is clear from the results shown in Table 1, it was confirmed that the resin composition of the present invention can achieve a very low dielectric constant (relative dielectric constant: 2.2 or less) in the cured product. Furthermore, the examples related to the present invention also had high oven heat resistance and excellent moldability. In addition, since the amount of ionic impurities was low, it was found that the moisture resistance reliability was also excellent.

[0164] In contrast, in Comparative Example 1, in which too much hollow inorganic particles were added, the viscosity of the resulting resin mixture when melted was too high, making it impossible to obtain a resin plate after curing, and evaluation tests could not be performed. On the other hand, in Comparative Example 2, in which too little hollow inorganic particles were added, an acceptable level of low dielectric constant was not achieved. Furthermore, in Comparative Example 3, in which hollow inorganic particles were used whose void ratio did not satisfy the requirements of the present invention, and in Comparative Example 4, in which a thermosetting resin (A) satisfying the requirements of the present invention was not used as the thermosetting resin, an acceptable level of low dielectric constant was not achieved. Furthermore, in Comparative Example 5, in which hollow inorganic particles not satisfying the requirements of the present invention were used, it was confirmed that there was a large amount of ionic impurity and that the moisture resistance reliability was poor.

[0165] This application is based on Japanese Patent Application No. 2024-045491 filed on March 21, 2024, the contents of which are incorporated herein by reference.

[0166] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments with reference to specific examples, drawings, etc., but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-described embodiments. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims.

[0167] The present invention has wide industrial applicability in technical fields related to electronic materials, electronic devices, optical devices, and the like.

Claims

1. A resin composition comprising a resin mixture containing a thermosetting resin (A) and an inorganic filler (B), wherein the cured product of the resin-containing mixture has a relative dielectric constant of 2.6 or less, the inorganic filler (B) has a relative dielectric constant of 1.8 or less at 10 GHz, and contains hollow inorganic particles (B-1) having a hollowness of 50% or more and 90% or less, and the specific surface area of ​​the hollow inorganic particles (B-1) is 30 m ２ / g or less, and the volume-based cumulative 50% particle size (D50) in the particle size distribution of the hollow inorganic particles (B-1) is 0.1 μm or more and 3.0 μm or less, and the content of the hollow inorganic particles (B-1) is 20 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the thermosetting resin (A).

2. The resin composition according to claim 1, wherein the hollow inorganic particles (B-1) include hollow silica particles.

3. The resin composition according to claim 1, wherein the inorganic filler (B) contains inorganic particles (B-2) different from the hollow inorganic particles (B-1).

4. The resin composition according to claim 1, wherein the thermosetting resin (A) contains at least one selected from the group consisting of polyphenylene ether compounds, hydrocarbon compounds, epoxy compounds, maleimide compounds, phenolic compounds, oxetane compounds, benzoxazine compounds, liquid crystal polymers, and compounds having a polymerizable unsaturated group.

5. The resin composition according to claim 1, wherein the cured product of said resin composition has a relative dielectric constant of 2.2 or less at 10 GHz.

6. A prepreg comprising the resin composition according to any one of claims 1 to 5 or a semi-cured product of said resin composition and a fibrous base material.

7. A resin-coated film having a resin layer containing the resin composition according to any one of claims 1 to 5 or a semi-cured product of said resin composition, and a support film.

8. A resin-coated metal foil comprising a resin layer containing the resin composition according to any one of claims 1 to 5 or a semi-cured product of said resin composition, and a metal foil.

9. A metal-clad laminate having an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 5 and a metal foil.

10. A metal-clad laminate having an insulating layer containing the cured product of the prepreg according to claim 6 and a metal foil.

11. A wiring board having an insulating layer containing a cured product of the resin composition according to any one of claims 1 to 5 and wiring.

12. A wiring board having an insulating layer containing the cured product of the prepreg according to claim 6 and wiring.

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