JP2014001277A - Curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable resin composition that provides a cured product having a low dielectric constant and a dielectric tangent, that provides a cured product in which formability at a normal press molding temperature is excellent and that has excellent heat resistance and adhesiveness, and further that can provide a laminate sheet that satisfies requirement of multi-layer and high frequency.SOLUTION: A curable resin composition includes: a polyphenylene ether (A); and an inorganic particle (B), wherein an average phenolic hydroxyl group number per one molecule of the polyphenylene ether (A) is at least 0.3, a content of silica (B) is at least 25 mass% and at most 80 mass% in the total mass of the curable resin composition, a resin flow amount of the curable resin composition when being cured is at least 0.3% and at most 15%, and the curable resin composition provides a cured product in which a dielectric tangent at 1GHz is at most 0.005 and a glass transformation temperature is at least 170°C.

Description

  The present invention relates to a curable resin composition containing polyphenylene ether suitable as an electronic substrate material. Furthermore, the present invention relates to a printed wiring board prepreg comprising the curable resin composition and a substrate, and a printed wiring board comprising a cured product of the curable resin composition and a substrate.

  In recent years, along with improvements in bonding and mounting technologies, electronic devices have been continuously developed along with higher integration of semiconductor devices mounted on electronic devices, more sophisticated packages, and higher density of printed wiring boards. . In a printed wiring board constituting this type of electronic device, both multilayering and fine wiring have progressed. It is effective to reduce the dielectric constant of the material used in order to realize a high signal transmission speed required for high-speed information processing. In order to suppress transmission loss, it is effective to use a material having a low dielectric loss tangent.

  Polyphenylene ether is suitable as a material for printed wiring boards of electronic equipment using a high frequency band because polyphenylene ether has excellent high-frequency characteristics (that is, dielectric characteristics) such as dielectric constant and dielectric loss tangent. However, polyphenylene ether, which is a thermoplastic resin, has insufficient heat resistance and dimensional stability. In addition, since polyphenylene ether generally has a high melting point, when forming a multilayer printed wiring board, there is a problem that the melt viscosity of the prepreg becomes high and molding defects such as voids and blurring occur.

  Patent Document 1 describes a resin composition containing polyphenylene ether and triallyl isocyanurate (TAIC) as a technique for improving the heat resistance and dimensional stability of polyphenylene ether which is a thermoplastic resin. In Patent Document 2, as a technique for improving chemical resistance, a resin composition containing maleated polyphenylene ether which is a reaction product of polyphenylene ether and maleic anhydride and TAIC is described. However, in the resin composition described in Patent Document 1 or 2, the melting point of the resin itself is high, and the viscosity at the time of melting is too high at a normal press molding temperature, so that an inner conductor pattern layer of a multilayer printed wiring board is formed. Filling is difficult. Therefore, there is a problem that it is difficult to make a multilayer wiring board.

  For the purpose of improving the above-described problems of moldability, Patent Document 3 uses a low molecular weight polyphenylene ether, which provides good flowability of the molten resin and excellent moldability at normal press molding temperatures. A polyphenylene ether resin composition that can be multilayered is described. However, reducing the molecular weight of polyphenylene ether causes problems such as a decrease in heat resistance of the resulting laminate and an increase in dielectric constant and dielectric loss tangent due to an increase in the number of terminal hydroxyl groups of polyphenylene ether. To do. Therefore, the above technique is also not sufficient for use in a printed wiring board.

  For the purpose of improving these problems associated with the lowering of the molecular weight of polyphenylene ether, Patent Documents 4 and 5 disclose low molecular weight / end-capped polyphenylene ethers in which the terminal hydroxyl groups of low molecular weight polyphenylene ethers are sealed with reactive functional groups. Is described. It is described that by using these polyphenylene ethers, a cured product that does not cause a decrease in heat resistance or a decrease in dielectric constant and dielectric loss tangent can be obtained while maintaining good moldability during press molding. .

  Patent Document 4 also describes a method in which a low molecular weight / end-capped polyphenylene ether and a normal polyphenylene ether are mixed and used. In Reference Example 7 of Patent Document 4, polyphenylene ether having a number average molecular weight of 14,000 and terminal ethenylbenzylated polyphenylene ether having a number average molecular weight of 2,500 are used in a mixing ratio of 5:70. A polyphenylene ether having a number average molecular weight of 14,000 and a terminal ethenylbenzylated polyphenylene ether having a number average molecular weight of 2,500 are used in a mixing ratio of 50:60.

A method of using a mixture of a normal molecular weight polyphenylene ether and a low molecular weight polyphenylene ether is also described in Patent Documents 6, 7 and the like. Patent Document 6 describes a technique in which 0.1% to 9.1% of polyphenylene ether is usually added to low molecular weight / terminal functionalized polyphenylene ether for the purpose of improving the heat resistance of the low molecular weight / terminal functionalized polyphenylene ether. Has been.
Patent Document 7 discloses a normal molecular weight polyphenylene ether functionalized with an acyl group or an electrophilic group (inherent viscosity of 0.35 dl / g or more) and a non-functionalized low molecular weight polyphenylene ether (inherent viscosity of about 0.15 to 0.35 dl). / G) is described in a resin composition using polyphenylene ether mixed at a ratio of 40 to 55:60 to 45.

JP-A-8-231847 Japanese Patent Publication No. 7-37567 JP 2002-265777 A JP 2008-260942 A Special table 2003-515642 gazette JP-A-2005-290124 US Pat. No. 5,258,455

  In general, inorganic particles are contained in a resin composition serving as a precursor of a substrate for the purpose of imparting various properties such as low thermal expansion and mechanical strength. On the other hand, however, when inorganic particles are usually contained, the resin melt viscosity at the time of press molding increases and the moldability decreases. In addition, when the resin composition is cured to form a laminate, the peel strength between the interlayer and the cured product of the resin composition and a metal foil such as a copper foil is lowered.

  And the low molecular weight and terminal functionalized polyphenylene ethers described in Patent Documents 4 and 5 have a problem that is presumed to be caused by sealing the terminal hydroxyl group. That is, such polyphenylene ether has insufficient adhesion to a substrate such as a glass cloth or copper foil, and the peel strength between layers in the case of a laminated board, or the peel strength between the polyphenylene ether and copper foil, etc. However, there is a problem that water resistance is low or water absorption resistance and solder heat resistance are not sufficient. In particular, insufficient adhesiveness of the resin used leads to a problem that the content of inorganic particles is limited. Further, in the laminates described in Reference Examples 7 and 8 of Patent Document 4, characteristics such as Tg, dielectric constant, dielectric loss tangent, moisture absorption, solder heat resistance, etc. are those of terminal ethenylbenzylated polyphenylene ether alone. The characteristics were not improved by using a mixture of low molecular weight, terminal ethenylbenzylated polyphenylene ether and normal polyphenylene ether.

  Further, Patent Document 6 only describes that the heat distortion temperature (HDT) of a cured resin plate is improved from about 100 ° C. to about 110 ° C. by adding polyphenylene ether having a normal molecular weight. There is no description of the properties (particularly moldability, peel strength, water absorption resistance, solder heat resistance, etc.) of the composite of the cured resin and the base material necessary for the printed wiring board, which is an application of the invention.

  Patent Document 7 only describes that the impact strength and the like of the extruded product are improved. Like Patent Document 6, the resin cured product and the base necessary for the printed wiring board, which is an application of the present invention, are described. There is no description of the properties (particularly moldability, peel strength, water absorption resistance, solder heat resistance, etc.) of the composite with the material.

  As described above, insulating resins for printed wiring boards that have the low dielectric constant and dielectric loss tangent inherent in polyphenylene ether and that are excellent in moldability, heat resistance, and adhesiveness at normal press temperatures are the conventional technologies. Is currently not found. Therefore, there has been a strong demand for an insulating resin for a printed wiring board having the above-described characteristics while using polyphenylene ether as a constituent component.

  Under the circumstances described above, the problem to be solved by the present invention is to give a cured product having a low dielectric constant and dielectric loss tangent inherent in polyphenylene ether, and is excellent in moldability at a normal press molding temperature, and more than a predetermined amount. Even if it contains inorganic particles, it has sufficient adhesion (for example, peel strength between layers in a multilayer board, or peel strength between a cured product of a curable resin composition and a metal foil such as a copper foil), and further excellent A curable resin composition that gives a cured product having high heat resistance, a prepreg for a printed wiring board containing the resin composition and a base material, and a printed wiring board containing the cured product of the resin composition and a base material It is to be.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and experiments while paying attention to the influence of the molecular weight and the number of terminal hydroxyl groups of polyphenylene ether on various properties required for printed wiring board materials. As a result, the average number of phenolic hydroxyl groups per molecule of polyphenylene ether is controlled within a specific range, and more preferably, the main component is a normal molecular weight polyphenylene ether and a specific amount of low molecular weight polyphenylene ether is blended. It has been found that a curable resin composition excellent in moldability and adhesiveness and a cured product having a low dielectric constant and dielectric loss tangent can be formed even if it contains inorganic particles of a certain amount or more.
That is, the present invention is as follows.

[1] A curable resin composition containing polyphenylene ether (A) and inorganic particles (B),
The average number of phenolic hydroxyl groups per molecule of the polyphenylene ether (A) is 0.3 or more,
The content of the inorganic particles (B) is 25% by mass or more and 80% by mass or less in the total mass of the curable resin composition,
The resin flow amount at the time of curing measured under the following conditions of the curable resin composition is 0.3% or more and 15% or less,
A dielectric loss tangent measurement sample produced from the curable resin composition under the following conditions has a dielectric loss tangent at 1 GHz: 0.005 or less,
The glass transition temperature measurement sample prepared from the curable resin composition under the following conditions has a glass transition temperature: 170 ° C. or higher,
The amount of resin flow at the time of curing is such that two prepregs of 150 mm square each impregnated with IPC Style 2116 standard glass cloth are laminated so that the curable resin composition has a resin content of 60 ± 2% by mass. The laminated plate precursor was molded under the following conditions (a), and the mass (g) of the laminated plate when the flowed resin part was removed to produce a laminated plate, and the laminated plate precursor From the mass (g) of the following formula:
Resin flow rate during curing (%) = (mass of laminate precursor (g) −mass of laminate (g)) / mass of laminate precursor (g) × 100
Is calculated according to
The dielectric loss tangent measurement sample was formed by stacking 16 prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition had a resin content of 60 ± 2% by mass, and molded under the following conditions (a): Has been
The glass transition temperature measurement sample is formed by stacking two prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass, and the following conditions (a) Molded,
Curable resin composition.
Condition (a)
Vacuum pressing is performed from room temperature at a heating rate of 3 ° C./min and a pressure of 5 kg / cm ^2. When reaching 130 ° C., heating is performed at a heating rate of 3 ° C./min and a pressure of 30 kg / cm ² . When the temperature reaches 200 ° C., the vacuum press is performed under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes.
[2] The polyphenylene ether (A) is (A-1) a polyphenylene having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 or more and 8,000 or less. Curable resin composition as described in said [1] which contains an ether component in the quantity of 1 to 40 mass% with respect to polyphenylene ether whole quantity.
[3] The polyphenylene ether (A) is
(A-1) a polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 to 8,000, and (A-2) number average A polyphenylene ether component having a molecular weight exceeding 8,000,
The content of (A-1) is 1% by mass or more and 40% by mass or less, based on the total mass of 100% by mass of (A-1) and (A-2), and Curable resin composition as described in said [1] whose content of (A-2) is 60 mass% or more and 99 mass% or less.
[4] (A-1) A polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 to 8,000 is polyphenylene ether. The curable resin composition according to the above [2] or [3], which is a benzylated polyphenylene ether having a structure in which at least one phenolic hydroxyl group at the molecular end is substituted with a benzyl group.
[5] The curable resin composition according to the above [1] to [4], wherein the inorganic particles (B) are silica.
[6] A dielectric loss tangent measurement sample produced from the curable resin composition under the following conditions has a dielectric loss tangent at 10 GHz: 0.007 or less,
The dielectric loss tangent measurement sample is formed by stacking eight prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass, and molded under the above condition (a). The curable resin composition according to any one of the above [1] to [5].
[7] A monomer (C) having two or more vinyl groups in the molecule and a reaction initiator (D) are further included, and the total of 100 parts by mass of the polyphenylene ether (A) and the monomer (C). On the other hand, the content of the monomer (C) is 10 parts by mass or more and 70 parts by mass or less, and the content of the reaction initiator (D) is 1 part by mass or more and 10 parts by mass or less [1] -Curable resin composition in any one of [6].
[8] The curable resin composition according to the above [7], wherein the monomer (C) is triallyl isocyanurate (TAIC).
[9] The curable resin composition according to [7] or [8], further including a flame retardant.
[10] A prepreg for a printed wiring board comprising the curable resin composition according to any one of [1] to [9] above and a substrate.
[11] A printed wiring board comprising a cured product of the curable resin composition according to any one of [1] to [9] and a base material.

  According to the present invention, a cured product having a low dielectric constant and dielectric loss tangent inherent in polyphenylene ether is provided, and even when inorganic particles are contained, the moldability at a normal press molding temperature is excellent, and adhesiveness (for example, , A curable resin that does not impair the peel strength between layers in a multilayer board or the peel strength between a cured product of a curable resin composition and a metal foil such as a copper foil, and further provides a cured product having excellent heat resistance. A prepreg for a printed wiring board containing the composition, the resin composition and the base material, and a printed wiring board containing a cured product of the resin composition and the base material can be provided.

  Examples of aspects of the present invention will be described in detail below, but the present invention is not limited to these aspects.

  One embodiment of the present invention provides a curable resin composition (hereinafter, also referred to as a polyphenylene ether-containing composition) containing polyphenylene ether and inorganic particles.

  The polyphenylene ether (A) contained in the curable resin composition of this embodiment is preferably the following general formula (1):

(In the formula, R1, R2, R3 and R4 each independently have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group that may be substituted, an amino group that may have a substituent, a nitro group, or a carboxyl group.

  Specific examples of polyphenylene ether include poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6-ethyl-1,4-phenylene ether), and poly (2-methyl-6). -Phenyl-1,4-phenylene ether), poly (2,6-dichloro-1,4-phenylene ether) and the like, and 2,6-dimethylphenol and other phenols (for example, 2,3,6-trimethyl) Phenol, 2-methyl-6-butylphenol, etc.) and polyphenylene ether copolymers obtained by coupling 2,6-dimethylphenol and biphenols or bisphenols, etc. A preferred example is poly (2,6-dimethyl-1,4-phenylene ether).

  In the present disclosure, polyphenylene ether means a polymer composed of a substituted or unsubstituted phenylene ether unit structure, but may contain other copolymerization components as long as the effects of the present invention are not impaired.

  In one embodiment of the present invention, the average number of phenolic hydroxyl groups per molecule of polyphenylene ether is 0.3 or more. In one aspect, the resin flow amount during curing measured under the following conditions of the curable resin composition is 0.3% or more and 15% or less. In one embodiment, a dielectric loss tangent measurement sample prepared from the curable resin composition under the following conditions has a dielectric loss tangent at 1 GHz: 0.005 or less. In one embodiment, the glass transition temperature measurement sample produced from the curable resin composition under the following conditions has a glass transition temperature of 170 ° C. or higher.

The amount of resin flow at the time of curing is such that two prepregs of 150 mm square each impregnated with IPC Style 2116 standard glass cloth are laminated so that the curable resin composition has a resin content of 60 ± 2% by mass. The laminated plate precursor was molded under the following conditions (a), and the mass (g) of the laminated plate when the flowed resin part was removed to produce a laminated plate, and the laminated plate precursor From the mass (g) of the following formula:
Resin flow rate during curing (%) = (mass of laminate precursor (g) −mass of laminate (g)) / mass of laminate precursor (g) × 100
Is a value calculated according to

Here, the condition (a) is defined as follows. Vacuum pressing is performed from room temperature at a heating rate of 3 ° C./min and a pressure of 5 kg / cm ^2. When reaching 130 ° C., heating is performed at a heating rate of 3 ° C./min and a pressure of 30 kg / cm ² . When the temperature reaches 200 ° C., the vacuum press is performed under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes.

  The dielectric loss tangent measurement sample was formed by stacking 16 prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition had a resin content of 60 ± 2% by mass, and molded under the above conditions (a). Has been.

  The glass transition temperature measurement sample is formed by stacking two prepregs impregnated with an IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass. Molded.

  The IPC Style 2116 standard glass cloth is commercially available, and is available, for example, under the trade name “2116” manufactured by Asahi Schwer Corporation.

  The resin flow amount during curing of the curable resin composition of the present invention is 0.3% or more and 15% or less, preferably 0.5% or more and 12% or less, more preferably 1% or more and 10% or less. When the resin flow amount is 0.3% or more, a cured product having excellent moldability at a normal press molding temperature and reduced haze and voids, and a laminate including the cured product can be formed. On the other hand, when the resin flow amount is 15% or less, for example, when forming a laminated board including a cured product of the curable resin composition and a base material, it is possible to reduce the lamination position deviation of the laminated board.

  Here, the amount of resin flow during curing of the curable resin composition is defined as a value obtained by the following method of the present disclosure, and more specifically, can be calculated using the following method.

  The amount of resin flow during curing was determined by testing a 150 mm square prepreg impregnated with IPC Style 2116 standard glass cloth glass cloth (IPC Style 2116) so that the curable resin composition had a resin content of 60 ± 2% by mass. A piece. The mass (g) of two test pieces is obtained in advance, and is defined as the mass of the laminated plate precursor. Next, two test pieces are stacked and heated and pressurized under the above condition (a). About the obtained thing, the resin part which flowed out from 150 square mm is removed, and it is set as a laminated board. The mass of this laminate is determined and is defined as the mass (g) of the laminate. The mass thus obtained is substituted into the above formula, and the amount of resin flow during curing is determined.

  An example of a method for adjusting the resin flow amount during curing to the above range is a method of adjusting the average number of phenolic hydroxyl groups per molecule of polyphenylene ether, (A-1) a low molecular weight / terminal functionalized polyphenylene ether described later, (A-2) A method of adjusting by mixing the components and changing the mixing ratio, a method of blending and using a monomer having two or more vinyl groups in the molecule, which will be described later, etc., etc. It is.

  Moreover, the dielectric loss tangent of the hardened | cured material sample produced on the following conditions of this indication from the curable resin composition of this aspect is 0.005 or less at 1 GHz. A printed wiring board having a dielectric loss tangent of 1 GHz at 0.005 or less is desired because it can suppress transmission loss that increases as the frequency of signals increases. The curable resin composition provided by the present invention can provide a cured product composite having a dielectric loss tangent of 0.005 or less at 1 GHz. Therefore, by using such a curable resin composition, a printed wiring board capable of suppressing transmission loss in a high frequency region can be formed.

  The cured material dielectric loss tangent measurement sample is a stack of 16 prepregs impregnated with IPC Style 2116 standard glass cloth glass cloth (IPC Style 2116) so that the curable resin composition has a resin content of 60 ± 2 mass%. It is produced by the method of heating and pressing under the above condition (a).

  The dielectric loss tangent at 1 GHz of the cured sample is preferably 0.003 or less, more preferably 0.001 or less. The smaller the dielectric loss tangent, the better. However, from the viewpoint of the electrical properties inherent in the polyphenylene ether, it can be preferably 0.0007 or more, more preferably 0.0005 or more.

Cured material The dielectric loss tangent of the above sample is a value obtained by measuring the capacitance Cp [F] and conductance G [S] of 1 MHz to 1 GHz under the condition of 500 mV by the impedance analyzer method and using the following equation. is there.
εr = (t × Cp) / {π × (d / 2) ² × ε0
(T: sample thickness [m], d: electrode diameter, f: measurement frequency [Hz], ε0: vacuum permittivity = 8.854 × 10 ⁻¹² [F / m])

  In a preferred embodiment, a dielectric loss tangent measurement sample prepared from the curable resin composition under the following conditions has a dielectric loss tangent at 10 GHz: 0.007 or less. Here, the dielectric loss tangent measurement sample is formed by stacking eight prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass, and molded under the above condition (a). It has been done. A dielectric loss tangent at 10 GHz of 0.007 or less is suitably used in terms of suppressing transmission loss in a laminated plate used in a so-called ultra-high frequency region such as an X band region used for satellite communication or the like. The The dielectric loss tangent at 10 GHz is more preferably 0.0065 or less, and still more preferably 0.006 or less. The smaller the dielectric loss tangent, the better. However, from the viewpoint of the electrical properties inherent in the polyphenylene ether, it can be preferably 0.0005 or more, more preferably 0.0007 or more. The dielectric loss tangent is measured using a cavity resonator using a vector network analyzer at a frequency of 10 GHz.

  Further, in the curable resin composition of this embodiment, the sample prepared by the above-described method of the present disclosure (specifically, at 1 GHz except that two prepregs are stacked instead of 16 prepregs). Sample produced by the same method as the production method of the dielectric loss tangent measurement sample) The glass transition temperature of the cured product is 170 ° C. or higher, preferably 180 ° C. or higher, more preferably 190 ° C. or higher. The glass transition temperature of the sample corresponds to the glass transition temperature of a cured product obtained by curing the curable resin composition under typical use conditions. A cured product having a glass transition temperature of 170 ° C. or higher exhibits good heat resistance (particularly solder heat resistance corresponding to lead-free solder). The glass transition temperature of the cured product is preferably higher, but from the viewpoint of applicability to the use environment of the cured product, the glass transition temperature of the sample is preferably 300 ° C. or less, more preferably 250 ° C. or less. Can do.

  Here, the glass transition temperature of the sample cured product is a value measured using a viscoelastic spectrometer under conditions of a twist mode and a frequency of 10 rad / s.

  An example of a method for adjusting the glass transition temperature to the above range is a method of adjusting the average number of phenolic hydroxyl groups per molecule of polyphenylene ether, and the components (A-1) and (A-2) described later are mixed. , A method of adjusting the mixing ratio, a method of using and blending a monomer having two or more vinyl groups in the molecule, which will be described later, and preparing a blending amount thereof.

  The average number of phenolic hydroxyl groups per molecule of the polyphenylene ether contained in the curable resin composition of this embodiment is 0.3 or more. The average number of phenolic hydroxyl groups per molecule of polyphenylene ether is preferably 0.7 or more, more preferably 0.9 or more, and further preferably 1.05 or more. When polyphenylene ether having an average number of phenolic hydroxyl groups per molecule of 0.3 or more is used in the curable resin composition, the adhesion between the cured product of the resin composition and a substrate (for example, glass cloth), or Adhesiveness between the cured product of the resin composition and a metal foil such as copper foil is improved, and water absorption resistance, solder heat resistance, and adhesiveness of a printed wiring board (for example, peeling strength between layers in a multilayer board, or curing) This is preferable because it is excellent in the peel strength between the product and the copper foil. The average number of phenolic hydroxyl groups is a viewpoint that can suppress an increase in water absorption of a composite (for example, a laminate) containing a cured product of the curable resin composition and a substrate, or a dielectric constant of the composite From the viewpoint of suppressing an increase in dielectric loss tangent, it is preferably 2.0 or less, more preferably 1.85 or less, and still more preferably 1.6 or less.

The average number of phenolic hydroxyl groups per molecule of polyphenylene ether in the present disclosure is defined as a value obtained by the following method. Polymer Papers, vol. 51, no. 7 (1994), in accordance with the method described on page 480, a value obtained by measuring an absorbance change at a wavelength of 318 nm of a sample obtained by adding a tetramethylammonium hydroxide solution to a methylene chloride solution of polyphenylene ether with an ultraviolet-visible spectrophotometer. To determine the number of hydroxyl groups. Separately, the number average molecular weight of polyphenylene ether is determined by gel permeation chromatography, and the molecular number of polyphenylene ether is determined using this value. From these values, the average number of hydroxyl groups per molecule of polyphenylene ether is calculated according to the following formula.
Average number of phenolic hydroxyl groups per molecule = number of hydroxyl groups / number average number of molecules

  The average number of phenolic hydroxyl groups per molecule of polyphenylene ether is, for example, polyphenylene ether in which the phenolic hydroxyl group at the molecular end remains and polyphenylene ether in which the phenolic hydroxyl group at the molecular end is modified with another functional group Can be adjusted by changing the mixing ratio. Or it can adjust also by changing the substitution degree by the other functional group of the phenolic hydroxyl group of a molecule terminal. The mode of the functional group is not particularly limited, and may be a benzyl group, an allyl group, a propargyl group, a glycidyl group, a vinylbenzyl group, a methacryl group, or the like. Among them, because of its high reaction efficiency, it is easy to obtain industrially, it has no reactivity and is excellent in stability, and the effect of reducing the melt viscosity of the polyphenylene ether-containing composition during press molding is remarkable. Preferably, it is a benzyl group.

  The polyphenylene ether used in this embodiment is (A-1) a polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 or more and 8,000 or less. It is preferable to contain 1% by mass or more and 40% by mass or less of low molecular weight / terminal-functionalized polyphenylene ether (hereinafter also referred to as low molecular weight / end-functionalized polyphenylene ether). A more preferable range of the content of the low molecular weight / end-functionalized polyphenylene ether is 1.2% by mass to 30% by mass, and a further preferable range is 1.5% by mass to 25% by mass.

  The number average molecular weight of the polyphenylene ether in the present disclosure is a value measured in terms of standard polystyrene using gel permeation chromatography (GPC). Typically, GPC measurement was performed under the same conditions using Shodex LF-804 × 2 (manufactured by Showa Denko KK) for the column, RI (refractometer) for the chloroform detector at 50 ° C. for the eluent. The number average molecular weight is calculated from the relational expression between the molecular weight of the standard polystyrene sample and the elution time.

  The (A-1) curable resin composition containing a polyphenylene ether containing 1% by mass or more of a low molecular weight / end-functionalized polyphenylene ether has a low melt viscosity at the time of molding and good moldability. Is preferable in that it is obtained. On the other hand, a curable resin composition containing polyphenylene ether containing 40% by mass or less of the low molecular weight / end-functionalized polyphenylene ether exhibits the characteristic of the low molecular weight / end-functionalized polyphenylene ether that the adhesion is poor. The water absorption resistance, solder heat resistance, and adhesiveness of a cured product (for example, the peel strength between layers in a multilayer board, or the cured product of a curable resin composition, which is desired in a printed wiring board, etc. And the peel strength between the copper foil and the like are preferable.

  The average number of phenolic hydroxyl groups per molecule of the (A-1) low molecular weight / end-functionalized polyphenylene ether is preferably less than 0.5, more preferably 0.2 or less. Preferably it is 0.1 or less. If the average number of phenolic hydroxyl groups is less than 0.5, the curable resin composition containing a low molecular weight and terminal-functionalized polyphenylene ether can form a cured product having a low dielectric constant and dielectric loss tangent. Since it has hardening reactivity, it is preferable at the point from which the hardened | cured material excellent in the mechanical characteristic and heat resistance is obtained. The average number of phenolic hydroxyl groups is preferably as small as possible, and may be 0, but from the viewpoint of the efficiency of modifying the phenolic hydroxyl groups with other functional groups, it is preferably 0.001 or more, more preferably 0.01. That's it.

  The number average molecular weight of the (A-1) low molecular weight / end-functionalized polyphenylene ether is preferably in the range of 1,000 to 8,000, more preferably 1,000 to 5,000. A more preferable range is 2,000 or more and 4,000 or less. A number average molecular weight of 8,000 or less is preferred because the melt viscosity at the time of molding of the curable resin composition containing the low molecular weight and terminal-functionalized polyphenylene ether is small and good moldability is obtained. On the other hand, if the number average molecular weight is 1,000 or more, the curable resin composition containing the low molecular weight / end-functionalized polyphenylene ether has low dielectric constant and dielectric loss tangent, and good heat resistance and mechanical properties. It is preferable at the point which can form hardened | cured material.

  (A-1) The mode of the terminal functional group in the low molecular weight / end-functionalized polyphenylene ether is not particularly limited, and is a benzyl group, an allyl group, a propargyl group, a glycidyl group, a vinylbenzyl group, a methacryl group or the like. be able to. Among them, since the reaction efficiency is good, it is easy to obtain industrially, it has no reactivity and is excellent in stability, and the effect of reducing the melt viscosity of the component (A-2) described later during press molding is remarkable. For this reason, the low molecular weight and terminally functionalized polyphenylene ether is preferably a benzylated polyphenylene ether having a structure in which at least one phenolic hydroxyl group at the molecular end of the polyphenylene ether is substituted with a benzyl group.

  The benzylated polyphenylene ether may have an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 to 8,000. The benzylated polyphenylene ether means a polymer having a structure in which a substituted or unsubstituted benzyl group is bonded to the molecular chain end of the substituted or unsubstituted polyphenylene ether.

  More typically, the benzylated polyphenylene ether of the present disclosure has the following general formula (2):

[Wherein, R5, R6, R7, R8 and R9 each independently represent a hydrogen atom, an alkyl group or a halogen atom, Z is an integer of 1 to 5, and J is the following general formula (1):

(Wherein R1, R2, 3 and R4 are as defined above.)
The polyphenylene ether molecular chain containing the unit structure represented by these is represented. ]
It has the structure represented by these.

  J may be substantially composed of only the structure represented by the general formula (1) as a unit structure. However, depending on the purpose, J may be combined with the unit structure represented by the general formula (1). A polymerization component may be included.

  In the general formula (2), from the viewpoint of reaction efficiency, it is preferable that R5, R6, R7, R8 and R9 are all hydrogen atoms.

  In the above general formula (2), since the molecular weight can be controlled relatively easily during the polymerization, it is easy to synthesize a polymer having a molecular weight distribution that is optimal for the application. Therefore, J represents poly (2,6-dimethyl- 1,4-phenylene ether) structure is preferable. A copolymer structure obtained by reacting poly (2,6-dimethyl-1,4-phenylene ether) with a phenol compound in the presence of an organic peroxide is preferable. The phenol compound used in this case is not particularly limited as long as it has one or more phenolic hydroxyl groups in the molecule. Specifically, phenol, cresol, 2,6-xylenol, 2,3,6-trimethylphenol, bisphenol A , Biphenol, cresol / novolak skeleton phenol and the like, and 2,6-xylenol, bisphenol A, and cresol / novolak skeleton phenol are preferably used from the viewpoint of high reaction rate.

  The benzylated polyphenylene ether may have a number average molecular weight in the range of 1,000 to 8,000, more preferably 1,000 to 5,000, and particularly preferably 2,000 to 4,000. is there. If the number average molecular weight is 8,000 or less, the benzylated polyphenylene ether is excellent in solubility in a solvent, and particularly 4,000 or less dissolves in toluene at a concentration of 30% by mass or more at room temperature (23 ° C.). On the other hand, when the number average molecular weight is 1,000 or more, the dielectric constant and dielectric loss tangent of the cured product of the curable resin composition containing benzylated polyphenylene ether can be lowered, and the heat resistance and mechanical properties of the cured product can be reduced. Excellent, especially 2,000 or more is preferable because the dielectric constant and dielectric loss tangent can be lowered.

  The average number of phenolic hydroxyl groups per molecule of the benzylated polyphenylene ether can be less than 0.5, more preferably less than 0.2, and particularly preferably less than 0.1. If the average number of phenolic hydroxyl groups is less than 0.5, the cured product of the curable resin composition containing benzylated polyphenylene ether has a low dielectric constant and dielectric loss tangent, and the composition has a curing reactivity. Since it is high, a cured product having excellent mechanical properties and heat resistance can be obtained. The average number of phenolic hydroxyl groups is preferably as small as possible, and may be 0. However, from the viewpoint of the efficiency of modifying the phenolic hydroxyl group with other functional groups, it is preferably 0.001 or more, more preferably 0.01. It can be more than one.

  The benzylated polyphenylene ether can typically be obtained by reaction of polyphenylene ether and a benzyl compound. For example, the benzylated polyphenylene ether includes a phenolic hydroxyl group possessed by a raw material polyphenylene ether (for example, a polyphenylene ether containing a unit structure represented by the above general formula (1)), and the following general formula (3):

(In the formula, R5, R6, R7, R8 and R9 are as defined in the general formula (2), and X represents a halogen atom or a cyano group.)
It is obtained by reaction with a benzyl compound represented by

  In the general formula (3), examples of X include F, Cl, Br, I, CN, and the like. Specific examples of the benzyl compound represented by the general formula (3) include benzyl chloride, benzyl cyanide, benzyl bromide, methyl benzyl chloride, methyl benzyl bromide, dimethyl benzyl chloride, dimethyl benzyl bromide, trimethyl benzyl chloride, trimethyl benzyl. Of these, benzyl chloride is preferred because it has high reactivity with phenolic hydroxyl groups and can easily produce benzylated polyphenylene ethers with a small number of phenolic hydroxyl groups.

  Although the manufacturing method of the said benzylated polyphenylene ether is not specifically limited, For example, the method of making a polyphenylene ether and a benzyl compound react in a solution, such as toluene and xylene, using a strong alkali compound as a catalyst is mentioned. Examples of strong alkali compounds include metal hydroxides such as sodium hydroxide, potassium hydroxide and calcium hydroxide, and alcoholates such as sodium methylate and sodium ethylate.

  In a preferred embodiment, the above-mentioned low molecular weight / end-functionalized polyphenylene ether and (A-2) polyphenylene ether having a number average molecular weight exceeding 8,000 are combined. As such component (A-2), the number of terminal phenolic hydroxyl groups is preferably larger than that of the low molecular weight / terminal functionalized polyphenylene ether, and more preferably the average number of phenolic hydroxyl groups per molecule is 0.5 or more. It is.

  In particular, when the polyphenylene ether contains 1% by mass or more and 40% by mass or less of the low molecular weight / end-functionalized polyphenylene ether, the polyphenylene ether has an average number of phenolic hydroxyl groups per molecule of 0.5 or more, and It is also preferable to include a polyphenylene ether component (hereinafter also referred to as unfunctionalized polyphenylene ether) having a number average molecular weight of more than 8,000 and 40,000 or less.

In a preferred embodiment, the polyphenylene ether is
(A-1) a polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 to 8,000, and (A-2) number average A polyphenylene ether component having a molecular weight exceeding 8,000 is included, and the content of (A-1) is 1% by mass or more and 40% by mass based on the total mass of 100% by mass of (A-1) and (A-2). % And the content of (A-2) is 60% by mass or more and 99% by mass or less.

  In this embodiment, the polyphenylene ether preferably consists essentially of (A-1) and (A-2), more preferably (A-1) and (A-2).

  By using the component (A-2), a high glass transition temperature derived from polyphenylene ether having a large molecular weight can be obtained. In addition, by using the component (A-2) in a preferred embodiment, good adhesiveness derived from the terminal hydroxyl group can be obtained, and the advantages of excellent heat resistance, mechanical properties, and adhesiveness can be obtained.

  The average number of phenolic hydroxyl groups per molecule of the component (A-2) is preferably 0.5 or more, more preferably 0.8 or more, more preferably from the viewpoint of realizing good adhesiveness. Is 1.6 or more. Although it is preferable in terms of obtaining the above effect that the average number of phenolic hydroxyl groups is large, the water absorption of the cured product composite containing the cured product of the curable resin composition and the substrate is prevented from being increased, or From the viewpoint of preventing increase in dielectric constant and dielectric loss tangent, it is preferably 2 or less, more preferably 1.85 or less, and still more preferably 1.6 or less.

  A preferred range of the number average molecular weight of the component (A-2) is more than 8,000 and 40,000 or less, a more preferred range is 9,500 or more and 28,000 or less, and a more preferred range is 10,000 or more and 20 or less. , 000 or less. When the number average molecular weight is more than 8,000, a high glass transition temperature is obtained, so that a cured product having excellent heat resistance and mechanical properties is obtained. On the other hand, when the number average molecular weight is 40,000 or less, the melt viscosity at a normal press molding temperature is kept low, and good moldability is obtained, which is preferable.

  The content of (A-2) on the basis of a total of 100% by mass of (A-1) and (A-2) is preferably 60% by mass or more from the viewpoint of realizing a high glass transition temperature and good adhesiveness. More preferably, it is more than 60% by mass, more preferably 70% by mass or more, and still more preferably 75% by mass or more, from the viewpoint of reducing the melt viscosity of the curable resin composition at the time of molding and obtaining good moldability. Therefore, it is preferably 99% by mass or less, more preferably 98.8% by mass or less, and still more preferably 98.5% by mass or less. In another preferred embodiment, (A-1) :( A-2) = 5: 95 to 30:80 on a mass basis.

  The curable resin composition contains inorganic particles (B). By using inorganic particles, low thermal expansion, low dielectric loss tangent, and low frequency dependence can be obtained satisfactorily. Moreover, even if it uses the specific polyphenylene ether mentioned above in combination with an inorganic particle, it can maintain the adhesiveness favorable and can ensure the moldability which resists multilayering. Therefore, according to the curable resin composition of this embodiment, a desired laminated board that satisfies the demands for higher multilayers and higher frequencies can be formed.

  Content of an inorganic particle is 25 mass% or more and 80 mass% or less in the total mass of curable resin composition. The content is 25% by mass or more from the viewpoint of obtaining low thermal expansion, low dielectric loss tangent, and low frequency dependence to a desired level, and obtains the effects of adhesiveness and moldability by polyphenylene ether to a desired level. From a viewpoint, it is 80 mass% or less. The content is preferably 25% by mass or more and 70% by mass or less, and more preferably 25% by mass or more and 60% by mass or less.

  Although it does not specifically limit as a material of an inorganic particle, From a viewpoint of using for an electronic material use, a silica, aluminum hydroxide, an alumina, E glass, S glass, D glass, H glass, boron nitride, and Aluminum nitride is preferred, and silica is most preferred in that it has low thermal expansion and low dielectric properties in the high frequency region. In addition, kaolin, talc, mica, clay, magnesium hydroxide, molybdenum oxide, titanium oxide, zinc oxide, barium titanate, and the like can be used. Different inorganic particles can also be combined. The inorganic particles preferably contain silica, more preferably silica. In the case where silica is contained in the inorganic particles, either one of crystalline silica and amorphous silica or a combination thereof may be used, but amorphous silica is preferably used from the viewpoint of dielectric constant.

  The average particle diameter of the inorganic particles is preferably 0.1 μm or more, more preferably 0.5 μm or more, from the viewpoint of suppressing a decrease in fluidity of the molten resin during press molding. Further, it is preferably 20 μm or less, more preferably 15 μm, and even more preferably 10 μm or less from the viewpoint of avoiding a decrease in insulation reliability and avoiding deterioration of the appearance of the laminate due to the recent thinning of the laminate. Most preferably, it is 5 μm or less. Here, the average particle size refers to a particle size corresponding to a cumulative distribution of 50%. In addition, inorganic particles having different particle sizes and particle size distributions can be combined.

  The shape of the inorganic particles may be any shape such as a spherical shape, a pulverized powder shape, a needle shape, or a short fiber shape, but a spherical shape is preferable from the viewpoint of suppressing a decrease in fluidity of the molten resin during press molding.

The surface of the inorganic particles is preferably one that has been surface-treated with a silane coupling agent or the like from the viewpoint that the heat resistance deterioration of the laminate and the adhesiveness with the resin-inorganic particles can be suppressed. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-β- (N- Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ -(2-aminoethyl Aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, N-phenyl-γ- Aminopropyltrimethoxysilane, N-phenyl-γ-aminopropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, vinyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, methyltrimethoxysilane Dimethyldimethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, and the like.
In particular, treatment with high hydrophobicity is preferable. For example, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, vinyltrimethoxysilane, dimethyldi An ethoxysilane etc. are mentioned.
By increasing the hydrophobicity, it is possible to further increase the solder heat resistance during moisture absorption, suppress the increase in the dielectric constant and dielectric loss tangent during moisture absorption, and adhere to the laminate (for example, between the layers in the laminate). Peel strength or peel strength between a cured product of the curable resin composition and a metal foil such as a copper foil) and insulation reliability can be improved.

  The curable resin composition can further contain a monomer (C) having two or more vinyl groups in the molecule. The curable resin composition has two or more vinyl groups in the molecule with respect to 100 parts by mass in total of the polyphenylene ether (A) and the monomer (C) having two or more vinyl groups in the molecule. The monomer (C) is preferably contained in an amount of 5 to 95 parts by mass, more preferably 10 to 80 parts by mass, still more preferably 10 to 70 parts by mass, and still more preferably 20 to 70 parts by mass. When the amount of the monomer (C) is 5 parts by mass or more, it is preferable in terms of good moldability, and when it is 95 parts by mass or less, it is preferable in that a cured product having a low dielectric constant and dielectric loss tangent can be formed.

  Further, in the curable resin composition, the content (a) of the above component (A-1), the content of the monomer (C) having two or more vinyl groups in the molecule (particularly preferably TAIC) ( The composition ratio (a) / (c) to c) is preferably 5/95 to 95/5 (mass ratio). When the composition ratio is 5/95 or more, the resulting cured product preferably has a low dielectric constant and dielectric loss tangent, and when it is 95/5 or less, the moldability is good. The composition ratio is more preferably 20/80 to 90/10, and particularly preferably 30/70 to 80/20.

  In the present disclosure, examples of the monomer having two or more vinyl groups in the molecule include triallyl isocyanurate (TAIC), triallyl cyanurate, triallylamine, triallyl mesate, divinylbenzene, divinylnaphthalene, and divinylbiphenyl. However, TAIC having good compatibility with polyphenylene ether is preferable.

  More preferably, the curable resin composition of this embodiment is preferably a polyphenylene ether (A), inorganic particles (B), a monomer (C) having two or more vinyl groups in the molecule, and a reaction initiator (D ).

  As the reaction initiator (D), any initiator having the ability to promote the polymerization reaction of a vinyl monomer can be used. For example, benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5- Dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, α, α′-bis (t -Butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylper Oxybenzoate, 2,2-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) octane, 2, Examples thereof include peroxides such as 5-dimethyl-2,5-di (benzoylperoxy) hexane, di (trimethylsilyl) peroxide, and trimethylsilyltriphenylsilyl peroxide. A radical generator such as 2,3-dimethyl-2,3-diphenylbutane can also be used as a reaction initiator. Among them, 2,5-dimethyl-2,5-di (t-butylperoxy) is preferable from the viewpoint of obtaining a cured product having excellent heat resistance and mechanical properties and having a lower dielectric constant and dielectric loss tangent. Hexin-3, α, α′-bis (t-butylperoxy-m-isopropyl) benzene and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane are preferred.

  From the viewpoint of increasing the reaction rate, the content of the reaction initiator (D) is preferably 0.5 parts by mass or more, more preferably 100 parts by mass in total of the polyphenylene ether (A) and the monomer (C). 1 part by mass or more, more preferably 1.5 parts by mass or more, and from the viewpoint that the dielectric constant and dielectric loss tangent of the obtained cured product can be kept low, preferably 15 parts by mass or less, more preferably 10 parts by mass or less. More preferably, it is 7 parts by mass or less.

  In a preferred embodiment, the content of the monomer (C) is 10 parts by mass or more and 70 parts by mass or less, and the content of the reaction initiator (D) with respect to 100 parts by mass in total of the polyphenylene ether (A) and the monomer (C). The amount is 1 part by mass or more and 10 parts by mass or less.

  The curable resin composition of the present invention may further contain another resin (for example, a thermoplastic resin or a curable resin). Thermoplastic resins include ethylene, propylene, butadiene, isoprene, styrene, divinylbenzene, methacrylic acid, acrylic acid, methacrylic ester, acrylic ester, vinyl chloride, acrylonitrile, maleic anhydride, vinyl acetate, ethylene tetrafluoride, etc. Examples thereof include homopolymers of vinyl compounds and copolymers of two or more vinyl compounds, and polyamides, polyimides, polycarbonates, polyesters, polyacetals, polyphenylene sulfides, polyethylene glycols, and the like. Among these, a styrene homopolymer, a styrene-butadiene copolymer, and a styrene-ethylene-butadiene copolymer can be preferably used from the viewpoints of solubility of the curable resin composition in a solvent and moldability. Examples of the curable resin include phenol resins, epoxy resins, and cyanate esters. The thermoplastic resin and curable resin may be modified with a functional compound such as an acid anhydride, an epoxy compound, or an amine. The amount of such another resin used is preferably 10 to 90 parts by mass, more preferably 20 to 70 parts by mass with respect to 100 parts by mass in total of the polyphenylene ether (A) and the monomer (C). is there.

  The curable resin composition of the present invention may further contain an appropriate additive depending on the purpose. Examples of the additive include a flame retardant, a heat stabilizer, an antioxidant, a UV absorber, a surfactant, a lubricant, a filler, and a polymer additive.

  In particular, when the curable resin composition of the present invention further contains a flame retardant, the present invention has good moldability, water absorption resistance, solder heat resistance, and adhesiveness (for example, peel strength between layers in a multilayer board, or In addition to the advantage that a printed wiring board having excellent peel strength between a cured product and copper foil or the like can be obtained, it is preferable in that flame retardancy can be imparted.

  The flame retardant is not particularly limited as long as it has a function of hindering the combustion mechanism. Inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, zinc borate, hexabromobenzene, decabromobenzene And aromatic bromine compounds such as phenylethane, 4,4-diphbromophenyl, and ethylenebistetrabromophthalimide. Of these, decabromojephenylethane is preferred from the viewpoint of keeping the dielectric constant and dielectric loss tangent of the cured product low.

  The amount of flame retardant used varies depending on the flame retardant used, and is not particularly limited. From the viewpoint of maintaining flame retardancy at the UL standard 94V-0 level, the total of polyphenylene ether (A) and monomer (C) Preferably it is 5 mass parts or more with respect to 100 mass parts, More preferably, it is 10 mass parts or more, More preferably, it is 15 mass parts or more. Moreover, from a viewpoint which can maintain the dielectric constant and dielectric loss tangent of the hardened | cured material small, Preferably it is 50 mass parts or less, More preferably, it is 45 mass parts or less, More preferably, it is 40 mass parts or less.

  A varnish containing the curable resin composition described above is also disclosed. The varnish can be formed by dissolving or dispersing the curable resin composition of the present invention in a solvent. After impregnating the varnish with a base material such as glass cloth, the solvent content is removed by drying, whereby a prepreg suitable as a material for the insulating layer of the substrate material can be produced.

  Examples of the solvent used for the varnish include toluene, xylene, methyl ethyl ketone, and acetone. These solvents can be used alone or in combination of two or more. For example, you may combine 1 or more types of said various solvents, and alcohols, such as methanol. The ratio of the curable resin composition in the varnish is 5 to 95 parts by mass with respect to 100 parts by mass of the varnish from the viewpoint of satisfactorily controlling the varnish impregnation property to the substrate and the resin adhesion amount to the substrate. It is preferable that it is 20 to 80 parts by mass.

  Another aspect of the present invention provides a prepreg comprising the curable resin composition of the present invention described above and a substrate. The prepreg is typically a printed circuit board prepreg. A typical prepreg is a composite of a curable resin composition and a substrate obtained by impregnating a varnish containing the curable resin composition into a substrate and then volatilizing the solvent with a hot air dryer or the like. Is the body. As the base material, various glass cloths such as roving cloth, cloth, chopped mat, and surfacing mat; asbestos cloth, metal fiber cloth, and other synthetic or natural inorganic fiber cloth; wholly aromatic polyamide fiber, wholly aromatic polyester fiber Woven or non-woven fabrics obtained from liquid crystal fibers such as polybenzoxazole fibers; natural fiber fabrics such as cotton cloth, linen cloth and felt; carbon fiber cloth, kraft paper, cotton paper, cloth obtained from paper-glass mixed yarn, etc. Natural cellulose base materials; polytetrafluoroethylene porous films; etc. can be used alone or in combination of two or more.

  The proportion of the curable resin composition in the prepreg is preferably 30 to 80 parts by mass, more preferably 40 to 70 parts by mass with respect to 100 parts by mass of the total amount of prepreg. When the proportion is 30 parts by mass or more, excellent insulation reliability is obtained when the prepreg is used for forming an electronic substrate, for example. When the ratio is 80 parts by mass or less, the obtained electronic substrate has a flexural modulus, etc. Excellent mechanical properties.

  By using the curable resin composition of the present invention described above, a laminate in which a cured product composite containing a cured product of the curable resin composition and a substrate and a metal foil are laminated can be formed. The laminate is preferably one in which the cured product composite and the metal foil are in close contact with each other, and is suitably used as a material for an electronic substrate. As the metal foil, for example, an aluminum foil and a copper foil can be used, and among them, the copper foil is preferable because of its low electric resistance. The cured product composite to be combined with the metal foil may be one sheet or a plurality of sheets, and the metal foil is overlapped on one side or both sides of the composite to be processed into a laminate according to the use. As a manufacturing method of a laminated board, for example, a composite composed of a curable resin composition and a base material (for example, the above-described prepreg) is formed, and this is overlapped with a metal foil. The method of obtaining the laminated board on which the hardened | cured material laminated body and metal foil are laminated | stacked by making it harden | cure is mentioned. One particularly preferred application of the laminate is a printed wiring board.

  Another aspect of the present invention provides a printed wiring board comprising a cured product of the curable resin composition of the present invention described above and a base material. The printed wiring board of the present invention can typically be formed by a method of pressure and heat molding using the prepreg of the present invention described above. Examples of the substrate include the same materials as described above with respect to the prepreg. Since the printed wiring board of the present invention is formed using the curable resin composition as described above, it can have excellent insulation reliability and mechanical properties.

  Hereinafter, the present embodiment will be described in more detail by way of examples. However, the present embodiment is not limited to the following examples.

  Each physical property in Examples, Comparative Examples and Production Examples was measured by the following method.

(1) Number average molecular weight of polyphenylene ether Using gel permeation chromatography analysis (GPC), the number average molecular weight was determined by comparison with the elution time of standard polystyrene having a known molecular weight.
HLC-8220GPC (manufactured by Tosoh Corporation) is used as a measuring apparatus, and measurement is performed under the conditions of column: Shodex LF-804 × 2 (manufactured by Showa Denko KK), eluent: chloroform at 50 ° C., detector: RI went.

(2) Average number of phenolic hydroxyl groups per molecule of polyphenylene ether Using the number of phenolic hydroxyl groups contained in polyphenine ether determined from absorbance and the number of molecules of polyphenine ether determined from average molecular weight, the average per molecule The number of phenolic hydroxyl groups was determined.
First, collection of polymer papers, vol. 51, no. 7 (1994), in accordance with the method described on page 480, a value obtained by measuring an absorbance change at a wavelength of 318 nm of a sample obtained by adding a tetramethylammonium hydroxide solution to a methylene chloride solution of polyphenylene ether with an ultraviolet-visible spectrophotometer. From this, the number of hydroxyl groups was determined.
Separately, the number average molecular weight of polyphenylene ether was determined by gel permeation chromatography according to (1) above, and the number of molecules of polyphenylene ether was determined using this value. From these values, the average number of hydroxyl groups per molecule of polyphenylene ether was calculated according to the following formula.
Average number of phenolic hydroxyl groups per molecule = number of hydroxyl groups / number average number of molecules

(3) Resin flow amount at the time of curing of the curable resin composition When a prepreg was heated and pressed to produce a laminate, the original mass of the flowed out resin (subjected to heating and pressing) It was calculated | required as a ratio with respect to a prepreg.

  The curable resin composition is mixed with toluene to prepare a varnish, and the varnish is impregnated into a glass cloth (2116 manufactured by Asahi Kasei Shovel Co., Ltd.), then dried to remove the toluene solvent, and the resin content is about 60% by mass. A prepreg was prepared. Two pieces of the prepreg were cut into 150 mm squares to obtain test pieces. Here, the mass (g) of the two test pieces was determined and used as the mass of the laminate precursor.

Next, the two test pieces were stacked and vacuum-pressed under the condition of a pressure of 5 kg / cm ² while heating from room temperature at a heating rate of 3 ° C./min. When reaching 130 ° C., heating was performed at a heating rate of 3 ° C./min. While pressing at a pressure of 30 kg / cm ^{2, when} the temperature reaches 200 ° C., the pressure is kept at 200 ° C. and the pressure is 30 kg / cm ² for 60 minutes. The resin was removed to obtain a laminate. Mass was calculated | required about this laminated board, and it was set as the mass (g) of the laminated board.
Using the mass (g) of the laminate precursor and the mass (g) of the laminate, the resin flow amount (%) during curing of the curable resin composition was determined from the following formula.
Resin flow rate during curing (%) = (mass of laminate precursor (g) −mass of laminate (g)) / mass of laminate precursor (g) × 100

(4) Glass transition temperature of laminated plate The dynamic viscoelasticity of the laminated plate was measured, and the temperature at which tan δ was maximized was determined.
Measurement was performed using ARESS (manufactured by TA Instruments) as a measuring apparatus under the conditions of a test piece: length of about 45 mm, width of about 12.5 mm, thickness of about 3 mm, twist mode, and frequency: 10 rad / s.

(5) Dielectric constant and dielectric loss tangent of laminate (5-1) Measurement at 1 GHz The dielectric constant and dielectric loss tangent at 1 GHz of the laminate were measured using an impedance analyzer.
Using an impedance analyzer (4291B op.002 with 16453A, 16454A, manufactured by Agilent Technologies) as a measuring device, the test piece thickness is about 2 mm, the voltage is 100 mV, the frequency is 1 MHz to 1.8 GHz, and the number of sweeps is 100. It calculated | required as an average value of times.
(5-2) Measurement at 10 GHz The dielectric loss tangent of the laminated plate at 10 GHz was measured using a vector network analyzer.
As a measuring device, a vector network analyzer (manufactured by E8362B Agilent Technologies) was used, and a test piece: a cavity resonator (CP531 Kanto Electronics) under the conditions of a length of about 50 mm, a width of about 1.5 mm, a thickness of about 1.5 mm, and a frequency of 10 GHz. Measured using an applied development).

(6) Water Absorption Rate of Laminate Plate The laminate plate was subjected to a water absorption acceleration test, and the water absorption rate was determined from the increased mass.
The laminate was cut into 50 mm squares to produce test pieces. After the test piece was dried at 130 ° C. for 30 minutes, the mass was measured to obtain the mass (g) before the acceleration test. Subsequently, the mass after the acceleration test was performed under the conditions of temperature: 121 ° C., pressure: 2 atm, and time: 4 hours, and the mass (g) after the acceleration test was measured.
Using the mass (g) before the acceleration test and the mass (g) after the acceleration test, the water absorption was calculated by the following formula, and the average value of the measured values of the four test pieces was obtained.
Water absorption (mass%) = (mass before acceleration test−mass after acceleration test) / mass before acceleration test × 100

(7) Solder heat resistance after water absorption test of laminated board A solder heat resistance test was performed at 288 ° C and 260 ° C using the laminated board after measuring the water absorption rate described in (6) above. The laminated board after the water absorption acceleration test was immersed in a solder bath at 288 ° C. or 260 ° C. for 20 seconds, and visually observed. A laminated board in which neither swelling, peeling or whitening was confirmed even when immersed in a solder bath at 288 ° C. was evaluated as “solder heat resistance 288 ° C.”. In addition, any one or more of swelling, peeling and whitening occurred by immersion in a solder bath at 288 ° C., but neither swelling nor peeling or whitening was confirmed even when immersed in a solder bath at 260 ° C. The laminated board was evaluated as “solder heat resistance 260 ° C.”. Moreover, the laminated board which generate | occur | produced any one or more of a swelling, peeling, and whitening by immersion in a 260 degreeC solder bath was evaluated as "failed."

(8) Copper foil peeling strength of laminated board The stress at the time of peeling the copper foil of a copper clad laminated board at a fixed speed was measured. A copper-clad laminate using a 35 μm copper foil (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) produced by the method described below was cut into a size of 15 mm wide × 150 mm long, and an autograph (AG-5000D, Shimadzu Corporation) was used to measure the average value of the load when the copper foil was peeled off at a speed of 50 mm / min at an angle of 90 ° C. with respect to the removal surface, and the average value of five measurements was obtained. .
(9) Thermal expansion coefficient of laminated board The thermal expansion coefficient in the lamination direction of the laminated board was measured using TMA (SS6600, manufactured by Seiko Instruments Inc.), test piece thickness: about 1.3 mm, temperature increase rate of 10 ° C / min. Mode: An average coefficient of thermal expansion from 50 ° C. to 100 ° C. was measured in the compression mode.

The raw materials used in Examples, Comparative Examples and Production Examples are shown below.
Polyphenylene ether: S202A (manufactured by Asahi Kasei Chemicals, number average molecular weight 19,000, average number of phenolic hydroxyl groups per molecule 1.84)
Bisphenol A: Tokyo Chemical Industry Co., Ltd. 6 mass% cobalt naphthenate mineral spirit solution: Wako Pure Chemical Industries, Ltd. Benzoyl peroxide solution: Niper BMT K-40 (manufactured by NOF, 40 mass% xylene solution of benzoyl peroxide)
Tetrabutylammonium iodide: Wako Pure Chemical Industries, Ltd. Benzyl Chloride: Tokyo Kasei Kogyo Co., Ltd. Chloromethylstyrene: Wako Pure Chemical Industries, Ltd. Triallyl Isocyanurate: TAIC (Nippon Kasei)
Styrene elastomer: SOE L606 (Asahi Kasei Chemicals)
Inorganic particles: spherical silica CRS 10151-MSS8 (manufactured by Tatsumori, φ8 μm), spherical silica SC5500-SEV (manufactured by Admatechs, φ1.6 μm), boron nitride AP-10S (manufactured by MARUKA, φ3 μm), S glass (known method) S-glass is pulverized dry and then classified (φ4μm)
Decabromodiphenylethane: SAYTEX8010 (manufactured by Albemarle Japan)
α, α'-bis (t-butylperoxy-m-isopropyl) benzene: perbutyl P (manufactured by NOF Corporation)
Cresol / novolak skeleton phenolic resin: manufactured by Gunei Chemical Industry Co., Ltd. Grade: Resitop PSM-4261
2,6-xylenol: manufactured by Tokyo Chemical Industry Co., Ltd. t-butyl peroxyisopropyl carbonate: Perbutyl I (manufactured by NOF Corporation)

<Production Example 1: Low molecular weight polyphenylene ether>
A 10 L flask was placed in an oil bath heated to 90 ° C., and nitrogen gas was introduced into the flask at a rate of 30 ml per minute. Thereafter, the operation was always performed under a nitrogen gas stream. 1 kg of polyphenylene ether and 3 kg of toluene were added and dissolved by stirring. Further, a solution obtained by dissolving 80 g of bisphenol A in 350 g of methanol was added to the flask with stirring. After stirring for 5 minutes, 3 ml of 6 mass% cobalt naphthenate mineral spirit solution was added with a syringe, and stirring was continued for 5 minutes. Subsequently, 1125 g of toluene was added to 375 g of the benzoyl peroxide solution, and a solution diluted so that the benzoyl peroxide concentration was 10% by mass was placed in a dropping funnel and dropped into the flask over 2 hours. After completion of the dropwise addition, the mixture was further heated and stirred for 2 hours to obtain a low molecular weight polyphenylene ether. The number average molecular weight of the obtained low molecular weight polyphenylene ether was 2,800, and the average number of phenolic hydroxyl groups per molecule was 1.96.

<Production Example 2: Low molecular weight / benzylated polyphenylene ether-1>
The same process as in Production Example 1 was carried out up to the step before methanol was added to precipitate polyphenylene ether to obtain a reaction solution containing low molecular weight polyphenylene ether. The temperature of the reaction solution was lowered to 50 ° C., an aqueous solution in which 340 g of sodium hydroxide was dissolved in 3050 g of ion-exchanged water and 31 g of tetrabutylammonium iodide were added and stirred for 5 minutes. Subsequently, after adding 1070 g of benzyl chloride, stirring was continued for 4 hours at a temperature of 50 ° C. to obtain a reaction solution containing a low molecular weight / benzylated polyphenylene ether. A large amount of methanol was added thereto to precipitate a low molecular weight / benzylated polyphenylene ether, which was filtered and dried to obtain a low molecular weight / benzylated polyphenylene ether-1.
The number average molecular weight of the obtained low molecular weight / benzylated polyphenylene ether-1 was 3,000, and the average number of phenolic hydroxyl groups per molecule was 0.01.

<Production Example 3: Low molecular weight / benzylated polyphenylene ether-2>
A low molecular weight polyphenylene ether was produced in the same manner as in Production Example 1 except that 100 g of bisphenol A, 440 g of methanol in which bisphenol A was dissolved, and 425 g of benzoyl peroxide solution were used, and the low molecular weight polyphenylene ether was used. In the same manner as in Production Example 2, low molecular weight and benzylated polyphenylene ether-2 was obtained.
The number average molecular weight of the obtained low molecular weight / benzylated polyphenylene ether-2 was 2,400, and the average number of phenolic hydroxyl groups per molecule was 0.02.

<Production Example 4: Low molecular weight / benzylated polyphenylene ether-3>
A low molecular weight polyphenylene ether is produced in the same manner as in Production Example 1 except that 130 g of bisphenol A, 570 g of methanol in which bisphenol A is dissolved, and 475 g of benzoyl peroxide solution are used, and the low molecular weight polyphenylene ether is used. In the same manner as in Production Example 2, low molecular weight and benzylated polyphenylene ether-2 was obtained.
The number average molecular weight of the obtained low molecular weight / benzylated polyphenylene ether was 1,500, and the average number of phenolic hydroxyl groups per molecule was 0.04.

<Production Example 5: Low molecular weight vinylbenzylated polyphenylene ether>
A low molecular weight vinylbenzylated polyphenylene ether was obtained in the same manner as in Production Example 2, except that 1070 g of benzyl chloride was changed to 1290 g of chloromethylstyrene.
The number average molecular weight of the obtained low molecular weight / vinylbenzylated polyphenylene ether was 3,100, and the average number of phenolic hydroxyl groups per molecule was 0.05.

<Examples 1 to 15 and Comparative Examples 1 to 10>
Varnishes were prepared by mixing varnishes having the resin compositions shown in Tables 1 and 2 using toluene. The varnish was impregnated in a glass cloth (trade name “2116”, manufactured by Asahi Sebel Co., Ltd.) and dried to obtain a prepreg having a resin content of 60% by mass. Using this prepreg, the amount of resin flow during curing was measured by the method described above.

In addition, two prepregs obtained as described above were stacked, and a copper foil having a thickness of 12 μm (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) was stacked on the top and bottom at a temperature rising rate of 3 ° C./min Perform vacuum pressing under heating at a pressure of 5 kg / cm ² , and when reaching 130 ° C, perform vacuum pressing under a pressure of 30 kg / cm ² while heating at a heating rate of 3 ° C / min. A double-sided copper-clad laminate was obtained by performing vacuum pressing under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes while maintaining the temperature at 200 ° C. Next, the copper clad laminate was cut into a 100 mm square, the copper foil was removed by etching, and a sample for evaluating the glass transition temperature, the water absorption rate, and the solder heat resistance after the water absorption test was obtained.

In addition, two prepregs obtained as described above are stacked, and a copper foil having a thickness of 35 μm (GTS-MP foil, manufactured by Furukawa Electric Co., Ltd.) is stacked on the top and bottom of the prepreg. Vacuum pressing under the condition of pressure 5 kg / cm ² while heating at 130 ° C, and when reaching 130 ° C, vacuum pressing is performed under the condition of pressure 30 kg / cm ² while heating at a heating rate of 3 ° C / min, reaching 200 ° C. Then, a double-sided copper-clad laminate was produced by performing vacuum pressing under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes while maintaining the temperature at 200 ° C. This double-sided copper-clad laminate was used as a sample for measuring the copper foil peel strength.

Also, 16 prepregs obtained as described above were stacked and vacuum-pressed under the condition of a pressure of 5 kg / cm ² while heating from room temperature at a heating rate of 3 ° C./min. Stacking is performed by performing vacuum pressing under the condition of a pressure of 30 kg / cm ² while heating in minutes, and when the pressure reaches 200 ° C., the pressure is maintained at a pressure of 30 kg / cm ² for 60 minutes while maintaining the temperature at 200 ° C. A plate was made. The laminate was cut into a 100 mm square and used as a sample for measuring dielectric constant and dielectric loss tangent.
In addition, 8 sheets of the prepreg obtained above were stacked and vacuum-pressed under the condition of a pressure of 5 kg / cm ² while heating from room temperature at a heating rate of 3 ° C./min. Stacking is performed by performing vacuum pressing under the condition of a pressure of 30 kg / cm ² while heating in minutes, and when the pressure reaches 200 ° C., the pressure is maintained at a pressure of 30 kg / cm ² for 60 minutes while maintaining the temperature at 200 ° C. A plate was made. The laminate was cut into 1.5 mm × 50 mm and used as a sample for measuring dielectric constant and dielectric loss tangent at 10 GHz. Moreover, this laminated board was cut out to 10 square mm, and it was set as the measurement sample of a thermal expansion coefficient.

  As mentioned above, using prepreg, double-sided copper-clad laminate (copper foil: 12 μm and 35 μm), or laminate, glass transition temperature, amount of resin flow during curing, copper foil peel strength, dielectric constant, dielectric The tangent, water absorption, and solder heat resistance after water absorption were measured and shown in Tables 1 and 2.

  As shown in Tables 1 and 2, in Examples 1 to 15, the resin flow amount is as large as 0.3% or more, the dielectric loss tangent at 1 GHz is as small as 0.005 or less, and the glass transition temperature is 170. Higher than ℃. The laminates of Examples 1 to 15 had high copper foil peel strength, good water absorption resistance, and excellent solder heat resistance.

  On the other hand, Comparative Examples 1 to 10 were inferior in at least one of resin flow amount, dielectric loss tangent, glass transition temperature, copper foil peel strength, thermal expansion coefficient, water absorption resistance, and solder heat resistance. In Comparative Examples 1 and 2 having a low inorganic particle content of 20% by mass, the dielectric loss tangent at 10 GHz and the coefficient of thermal expansion were high. Regarding Comparative Examples 3 to 5 having a silica content of 85% by mass, Comparative Example 3 had poor moldability, and the laminated plate was blurred. In this example, since a laminated board that can sufficiently withstand the evaluation could not be obtained, other items could not be evaluated. In Comparative Examples 4 and 5, the dielectric constant and the copper foil peel strength were poor. In Comparative Examples 5 and 6 using a mixture of polyphenylene ether with no terminal functionalization and low molecular weight polyphenylene ether, the glass transition temperature was low, the dielectric loss tangent was high, and the water absorption resistance and solder heat resistance were poor. In Comparative Example 7 where unfunctionalized polyphenylene ether and low molecular weight / benzylated polyphenylene ether were mixed at a ratio of 50:50 (mass ratio), the glass transition temperature was low, and the copper foil peel strength and solder heat resistance were poor. . In Comparative Example 8 where unfunctionalized polyphenylene ether and low molecular weight / vinylbenzylated polyphenylene ether were used in a mixing ratio of 46:54 (mass ratio), the copper foil peel strength was low and the solder heat resistance was poor. In Comparative Example 9 using a low molecular weight vinylbenzylated polyphenylene ether, the copper foil peel strength was low, and the water absorption resistance and solder heat resistance were poor. In Comparative Example 10 using unfunctionalized polyphenylene ether and using a large amount of triacyl isocyanurate to increase the fluidity of the molten resin, the dielectric loss tangent and dielectric constant are high, the copper foil peel strength is low, the water absorption resistance and Solder heat resistance was poor.

  While examples of aspects of the invention have been described above, it will be understood that the invention is not limited to these aspects and that various modifications are possible within the spirit and scope of the appended claims.

Claims (11)

A curable resin composition comprising polyphenylene ether (A) and inorganic particles (B),
The average number of phenolic hydroxyl groups per molecule of the polyphenylene ether (A) is 0.3 or more,
Content of the said inorganic particle (B) is 25 mass% or more and 80 mass% or less in this curable resin composition total mass,
The resin flow amount during curing measured under the following conditions of the curable resin composition is 0.3% or more and 15% or less,
A dielectric loss tangent measurement sample prepared from the curable resin composition under the following conditions has a dielectric loss tangent at 1 GHz: 0.005 or less,
The glass transition temperature measurement sample prepared from the curable resin composition under the following conditions has a glass transition temperature: 170 ° C. or higher,
The amount of resin flow at the time of curing is a laminate precursor obtained by stacking two 150 mm square prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass. The laminated plate precursor was molded under the following conditions (a), and the resin part that flowed out was removed to produce a laminated plate. The mass (g) of the laminated plate, and the laminated plate precursor From the mass (g) of the following formula:
Resin flow rate during curing (%) = (mass of laminate precursor (g) −mass of laminate (g)) / mass of laminate precursor (g) × 100
Is calculated according to
The dielectric loss tangent measurement sample was formed by stacking 16 prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition had a resin content of 60 ± 2% by mass, and molded under the following conditions (a): Has been
The sample for measuring the glass transition temperature is formed by stacking two prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass, and the following conditions (a) Molded,
Curable resin composition.
Condition (a)
Vacuum pressing is performed from room temperature at a heating rate of 3 ° C./min and a pressure of 5 kg / cm ^2. When reaching 130 ° C., heating is performed at a heating rate of 3 ° C./min and a pressure of 30 kg / cm ² . When the temperature reaches 200 ° C., the vacuum press is performed under the conditions of a pressure of 30 kg / cm ² and a time of 60 minutes.   The polyphenylene ether (A) is (A-1) a polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 or more and 8,000 or less. The curable resin composition according to claim 1, which is contained in an amount of 1% by mass or more and 40% by mass or less based on the total amount of polyphenylene ether. The polyphenylene ether (A) is
(A-1) a polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 to 8,000, and (A-2) number average A polyphenylene ether component having a molecular weight exceeding 8,000,
The content of (A-1) is 1% by mass to 40% by mass based on the total mass of 100% by mass of (A-1) and (A-2), and The curable resin composition of Claim 1 whose content of (A-2) is 60 mass% or more and 99 mass% or less.   (A-1) A polyphenylene ether component having an average number of phenolic hydroxyl groups per molecule of less than 0.5 and a number average molecular weight of 1,000 or more and 8,000 or less is at the molecular end of the polyphenylene ether. The curable resin composition according to claim 2 or 3, which is a benzylated polyphenylene ether having a structure in which at least one phenolic hydroxyl group is substituted with a benzyl group.   The curable resin composition according to any one of claims 1 to 4, wherein the inorganic particles (B) are silica. A dielectric loss tangent measurement sample prepared from the curable resin composition under the following conditions has a dielectric loss tangent at 10 GHz: 0.007 or less,
The dielectric loss tangent measurement sample is formed by stacking eight prepregs impregnated with IPC Style 2116 standard glass cloth so that the curable resin composition has a resin content of 60 ± 2% by mass, and molded under the condition (a). The curable resin composition according to any one of claims 1 to 5.   Further comprising a monomer (C) having two or more vinyl groups in the molecule and a reaction initiator (D), with respect to a total of 100 parts by mass of the polyphenylene ether (A) and the monomer (C), The content of the monomer (C) is 10 parts by mass or more and 70 parts by mass or less, and the content of the reaction initiator (D) is 1 part by mass or more and 10 parts by mass or less. 2. The curable resin composition according to item 1.   The curable resin composition according to claim 7, wherein the monomer (C) is triallyl isocyanurate (TAIC).   Furthermore, the curable resin composition of Claim 7 or 8 containing a flame retardant.   The prepreg for printed wiring boards containing the curable resin composition of any one of Claims 1-9, and a base material.   The printed wiring board containing the hardened | cured material and base material of the curable resin composition of any one of Claims 1-9.