Resin composition, cured product, prepreg, resin sheet, laminate, metal foil–clad laminate, and printed wiring board

Abstract

The purpose of the present invention is to provide: a resin composition that is ideal for production of an insulating layer for a printed wiring board that has a high dielectric constant, a low dielectric loss tangent, excellent thermal characteristics, excellent laser processability, and high metal foil peeling strength; and a prepreg, a resin sheet, a laminate, a metal foil–clad laminate, and a printed wiring board obtained using the resin composition.　This resin composition includes: a dielectric powder (A) that has a relative permittivity of at least 12.0 at a frequency of 10 GHz as measured in accordance with a cavity resonator perturbation method, an inorganic filler (B) that is different from the dielectric powder (A), has a melting point of no more than 1600°C, and has an absorbance of at least 0.70 at a wavelength of 9.3 μm on an infrared absorption spectrum obtained using Fourier transform infrared spectroscopy, and a thermosetting resin (C).

Description

Resin composition, cured product, prepreg, resin sheet, laminate, metal foil-clad laminate, and printed wiring board

[0001] The present invention relates to a resin composition, a cured product, a prepreg, a resin sheet, a laminate, a metal foil-clad laminate, and a printed wiring board.

[0002] In recent years, the signal bandwidth of information and communication devices such as PHS and mobile phones, as well as the CPU clock time of computers, have reached the GHz range, and frequencies are becoming increasingly higher. The dielectric loss of an electrical signal is proportional to the product of the square root of the relative permittivity of the insulating layer forming the circuit, the dielectric loss tangent, and the frequency of the electrical signal. Therefore, the higher the frequency of the signal used, the greater the dielectric loss. Since increased dielectric loss attenuates the electrical signal and impairs its reliability, to suppress this, it is necessary to select a material with a small dielectric loss tangent for the insulating layer.

[0003] On the other hand, for insulating layers of high-frequency circuits, there are demands for forming delay circuits, matching the impedance of wiring boards in low-impedance circuits, finer wiring patterns, and composite circuits with built-in capacitors in the board itself, which may require a high dielectric constant for the insulating layer. For this reason, electronic components using insulating layers with high dielectric constants and low dielectric loss tangents have been proposed (see, for example, Patent Document 1). High-dielectric-constant and low-dielectric-loss-tangent insulating layers are formed by dispersing fillers such as ceramic powder and insulating metal powder in a resin.

[0004] Furthermore, due to the miniaturization and high density of printed wiring boards, there has been active research into thinner laminates used in printed wiring boards. This thinning also requires thinner insulating layers. In this case, holes to ensure electrical continuity between insulating layers are generally drilled using laser processing.

[0005] Japanese Patent Application Laid-Open No. 2000-91717

[0006] Generally, to increase the dielectric constant of an insulating layer, it is necessary to incorporate a filler with a high dielectric constant, but at the same time, the dielectric loss tangent also increases, which causes the problem of increased transmission loss of high-frequency signals. Therefore, there is a demand for materials that maintain a high dielectric constant while at the same time having a lower dielectric loss tangent.

[0007] Furthermore, fillers used to manufacture insulating layers with high dielectric constants and low dielectric loss tangents can generate voids, which can cause delamination during the manufacture of laminates, resulting in problems such as deterioration of thermal properties such as moisture absorption and heat resistance, and dielectric properties (high dielectric constant and low dielectric loss tangent) in printed wiring boards and the like.

[0008] Furthermore, when holes are drilled by laser processing in a substrate on which a resin layer containing dielectric powder is laminated, the hole walls of the substrate are gouged out, which poses a problem of reduced insulation reliability between the hole walls when the substrate on which a resin layer containing dielectric powder is laminated is laser processed.

[0009] The insulating layer is required to have sufficient metal foil peel strength (for example, copper foil peel strength) when it is used to form a metal foil-clad laminate.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a resin composition that has a high dielectric constant and a low dielectric dissipation factor, as well as excellent thermal properties, excellent laser processability, and high metal foil peel strength, and is suitable for use in producing insulating layers of printed wiring boards; and to provide a cured product, prepreg, resin sheet, laminate, metal foil-clad laminate, and printed wiring board obtained using the resin composition.

[0011] As a result of extensive research into solving the above-mentioned problems of the conventional art, the present inventors have found that a specific resin composition can solve the above-mentioned problems, and have thus completed the present invention.

[0012] That is, the present invention is as follows: [1] A resin composition comprising: a dielectric powder (A) having a relative dielectric constant of 12.0 or more at a frequency of 10 GHz measured according to a cavity resonator perturbation method; an inorganic filler (B) and a thermosetting resin (C) different from the dielectric powder (A), the inorganic filler (B) having an absorbance of 0.70 or more at a wavelength of 9.3 μm in an infrared absorption spectrum obtained using Fourier transform infrared spectroscopy and a melting point of 1600° C. or less.

[0013] [2] The resin composition according to [1], wherein the mass ratio ((A):(B)) of the dielectric powder (A) to the inorganic filler (B) is 300:10 to 300:150.

[0014] [3] The resin composition according to [1] or [2], wherein the dielectric loss tangent of the dielectric powder (A) at a frequency of 10 GHz measured according to a cavity resonator perturbation method is 0.015 or less.

[0015] [4] The resin composition according to any one of [1] to [3], wherein the dielectric powder (A) contains a titanium-based inorganic filler.

[0016] [5] The resin composition according to [4], wherein the titanium-based inorganic filler comprises at least one selected from the group consisting of a surface-uncoated titanium-based inorganic filler and a surface-coated titanium-based inorganic filler.

[0017] [6] The resin composition according to [5], wherein the surface-uncoated titanium-based inorganic filler contains at least one selected from the group consisting of titanium monoxide, titanium dioxide, titanium trioxide, potassium titanate, calcium titanate, strontium titanate, barium titanate, aluminum titanate, and lead titanate.

[0018] [7] The resin composition according to [5] or [6], wherein the surface-coated titanium-based inorganic filler contains surface-coated titanium oxide.

[0019] [8] The resin composition according to [7], wherein the surface-coated titanium oxide has an organic layer and / or an inorganic oxide layer on the surface of titanium oxide particles.

[0020] [9] The resin composition according to any one of [1] to [8], wherein the inorganic filler (B) contains an alkaline earth metal silicate.

[0021]

[10] The alkaline earth metal silicate is Mg ２ Si ２ O ６ The resin composition according to [9], comprising an alkaline earth metal silicate having a structure:

[0022]

[11] The resin composition according to [9] or

[10] , wherein the alkaline earth metal silicate contains calcined talc.

[0023]

[12] The average particle diameter (D50) of the dielectric powder (A) is 0.10 μm or more and 10.00 μm or less, and the average particle diameter (D50) of the inorganic filler (B) is 0.10 μm or more and 10.00 μm or less. [1] The resin composition according to any one of [1] to

[11] .

[0024]

[13] The content of the dielectric powder (A) is 50 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the total resin solid content in the resin composition. [1] The resin composition according to any one of [1] to

[12] .

[0025]

[14] The content of the inorganic filler (B) is 10 parts by mass or more and 200 parts by mass or less relative to 100 parts by mass of the total resin solid content in the resin composition. [1] The resin composition according to any one of [1] to

[13] .

[0026]

[15] The resin composition according to any one of [1] to

[14] , wherein the thermosetting resin (C) comprises at least one selected from the group consisting of maleimide compounds, cyanate ester compounds, epoxy compounds, phenolic compounds, modified polyphenylene ether compounds, alkenyl-substituted nadimide compounds, oxetane resins, benzoxazine compounds, and compounds having a polymerizable unsaturated group.

[0027]

[16] The resin composition according to

[15] , wherein the maleimide compound comprises at least one selected from the group consisting of bis(4-maleimidophenyl)methane, 2,2-bis(4-(4-maleimidophenoxy)-phenyl)propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, maleimide compounds represented by the following formula (1), maleimide compounds represented by the following formula (2), maleimide compounds represented by the following formula (3), and maleimide compounds represented by the following formula (4):

[0028]

[0029] (In formula (1), R １ each independently represents a hydrogen atom or a methyl group, and n1 is an integer of 1 to 10.

[0030]

[0031] (In formula (2), R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group, and n2 is an average value and satisfies 1<n2≦5.

[0032]

[0033] (In formula (3), each Ra independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxy group, or a mercapto group. q represents an integer of 0 to 4. When q is an integer of 2 to 4, each Ra may be the same or different within the same ring. Each Rb independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. r represents an integer of 0 to 3. When r is 2 or 3, each Rb may be the same or different within the same ring. n3 is an average value of 0.95 to 10.0.)

[0034]

[0035] (In formula (4), R １ each independently represents an alkyl group having 1 to 10 carbon atoms, and s represents an integer of 1 to 3. ２ each independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. t represents an integer of 0 to 4. R ３ each independently represents a group represented by the following formula (5), and u represents an integer of 0 to 2. ４ represents a hydrogen atom or a group represented by the following formula (5): ５ represents a hydrogen atom or a group represented by the following formula (6), and n4 represents an integer of 1 to 100.

[0036]

[0037] (In formula (5), R ６ each independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. v represents an integer of 0 to 4. *1 represents the bonding site to the carbon atom.

[0038]

[0039] (In formula (6), R ７ each independently represents an alkyl group having 1 to 10 carbon atoms; and w represents an integer of 1 to 3. ８ each independently represents a group represented by the formula (5). x represents an integer of 0 to 2. *2 represents the bonding site to the carbon atom.

[0040]

[17] The resin composition according to

[15] or

[16] , wherein the cyanate ester compound is at least one selected from the group consisting of phenol novolac-type cyanate ester compounds, naphthol aralkyl-type cyanate ester compounds, naphthylene ether-type cyanate ester compounds, xylene resin-type cyanate ester compounds, bisphenol M-type cyanate ester compounds, bisphenol A-type cyanate ester compounds, diallyl bisphenol A-type cyanate ester compounds, bisphenol E-type cyanate ester compounds, bisphenol F-type cyanate ester compounds, and biphenyl aralkyl-type cyanate ester compounds, as well as prepolymers or polymers of these cyanate ester compounds.

[0041]

[18] The resin composition according to any one of

[15] to

[17] , wherein the epoxy compound comprises at least one selected from the group consisting of biphenylaralkyl epoxy resins, naphthalene epoxy resins, naphthylene ether epoxy resins, and butadiene skeleton-containing epoxy resins.

[0042]

[19] The resin composition according to any one of [1] to

[18] , which is for use in a printed wiring board.

[0043]

[20] A cured product comprising the resin composition according to any one of [1] to

[19] .

[0044]

[21] A prepreg comprising a substrate and the resin composition according to any one of [1] to

[19] impregnated into or coated on the substrate.

[0045]

[22] A resin sheet comprising the resin composition according to any one of [1] to

[19] .

[0046]

[23] A laminate comprising the prepreg according to

[21] .

[0047]

[24] A laminate comprising the resin sheet according to

[22] .

[0048]

[25] A metal foil-clad laminate comprising the laminate according to

[23] and a metal foil disposed on one or both sides of the laminate.

[0049]

[26] A metal foil-clad laminate comprising the laminate according to

[24] and a metal foil disposed on one or both sides of the laminate.

[0050]

[27] A printed wiring board having an insulating layer and a conductor layer disposed on one or both sides of the insulating layer, wherein the insulating layer contains a cured product of the resin composition according to any one of [1] to

[19] .

[0051] The resin composition of the present invention can provide a resin composition that has a high dielectric constant and a low dielectric dissipation factor, as well as excellent thermal properties, excellent laser processability, and high metal foil peel strength, and is suitable for use in producing insulating layers of printed wiring boards, as well as cured products, prepregs, resin sheets, laminates, metal foil-clad laminates, and printed wiring boards obtained using the resin composition.

[0052] Figure 1 shows an infrared absorption spectrum obtained using the KBr tablet method of Fourier transform infrared spectroscopy. Figure 2 shows the X-ray diffraction pattern of calcined talc. Figure 3 shows the X-ray diffraction pattern of finely powdered talc.

[0053] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0054] In this embodiment, unless otherwise specified, "resin solid content" or "resin solid content in a resin composition" refers to the resin components in the resin composition excluding the dielectric powder (A), inorganic filler (B), other fillers, additives (silane coupling agents, wetting and dispersing agents, curing accelerators, and other components), and solvents. "100 parts by mass of resin solid content" or "100 parts by mass of the total resin solid content in the resin composition" refers to the total of 100 parts by mass of the resin components in the resin composition excluding the dielectric powder (A), inorganic filler (B), other fillers, additives (silane coupling agents, wetting and dispersing agents, curing accelerators, and other components), and solvents.

[0055] [Resin Composition] The resin composition of the present embodiment includes a dielectric powder (A) (hereinafter also simply referred to as "dielectric powder (A)") having a relative dielectric constant of 12.0 or more at a frequency of 10 GHz measured according to a cavity resonator perturbation method, an inorganic filler (B) (hereinafter also simply referred to as "inorganic filler (B)") that is different from the dielectric powder (A) and has an absorbance of 0.70 or more at a wavelength of 9.3 μm in an infrared absorption spectrum obtained using Fourier transform infrared spectroscopy and a melting point of 1600° C. or less, and a thermosetting resin (C).

[0056] By using the resin composition of this embodiment, it is possible to suitably produce cured products, prepregs, resin sheets, laminates, metal foil-clad laminates, and printed wiring boards that have a high dielectric constant, a low dielectric loss tangent, excellent thermal properties such as moisture absorption heat resistance, excellent laser processability, and high metal foil peel strength. The resin composition of this embodiment is more suitably used for producing insulating layers of printed wiring boards.

[0057] The present inventors have discovered that by using a resin composition containing a specific dielectric powder (A), a specific inorganic filler (B), and a thermosetting resin (C) in the insulating layer of a printed wiring board, the substrate on which the insulating layer is laminated is less likely to have the hole walls of the substrate gouged when drilled by laser processing. Therefore, according to this embodiment, it is possible to obtain a cured product that has a high dielectric constant, a low dielectric loss tangent, excellent thermal properties such as moisture absorption and heat resistance, and high metal foil peel strength, while also being excellent in laser processability. Although the reason for this is unclear, the present inventors speculate as follows.

[0058] That is, in general, in the case of a printed wiring board, holes are drilled using carbon dioxide gas (CO ２ ) laser, mechanical drill, ultraviolet laser (UV laser), YAG laser, etc. are used, but carbon dioxide lasers are preferred because they can accurately drill small diameter holes and are excellent in processing speed and cost. However, when drilling using a carbon dioxide laser, if the insulating layer is formed from a resin composition containing an inorganic filler (B) with a relatively high melting point, the insulating layer tends to be difficult to drill using the heat of the carbon dioxide laser. Furthermore, at 9.3 μm, which is one of the wavelengths of a carbon dioxide laser, if the inorganic filler (B) has low absorbance at that wavelength, the energy of the carbon dioxide laser light is difficult to convert into heat, so the amount of energy required for drilling must be increased. This increases the amount of heat required for drilling, causing heat to propagate not only in the direction of laser irradiation but also horizontally. As a result, the hole wall surface of the substrate is easily gouged, posing a problem of reduced insulation reliability between the hole walls. Furthermore, the hollow wall surface of the substrate is gouged out, which causes problems such as a decrease in the thermal properties of the resin layer, such as moisture absorption and heat resistance, and a decrease in the metal foil peel strength.

[0059] On the other hand, the resin composition of this embodiment contains a specific dielectric powder (A) and a specific inorganic filler (B) in addition to the thermosetting resin (C). The inorganic filler (B) has a relatively low melting point. Therefore, an insulating layer formed from a resin composition containing the inorganic filler (B) is easily drilled using the heat of a carbon dioxide laser, even if it contains the dielectric powder (A) and other fillers blended as needed. Furthermore, the inorganic filler (B) has high absorbance at a wavelength of 9.3 μm. This allows the insulating layer to efficiently convert the energy of the carbon dioxide laser light into heat, reducing the amount of energy required for drilling and enabling a reduction in the amount of heat. As a result, heat propagation in the horizontal direction is reduced, allowing heat to propagate efficiently in the direction of laser irradiation. This results in suppression of gouging of the hole wall surface of the substrate and improved insulation reliability between the hole walls.

[0060] Furthermore, since the heat of the carbon dioxide laser is not excessively transmitted to the dielectric powder (A), there is no risk of the dielectric powder (A) being decomposed by irradiation with the carbon dioxide laser. Moreover, since gouging of the hole wall surface of the substrate is suppressed, the dielectric powder (A) is less likely to be exposed through the gouging. For these reasons, the insulating layer can preferably have the high dielectric constant and low dielectric loss tangent achieved by the dielectric powder (A).

[0061] Furthermore, since gouging of the hole wall surface of the substrate is suppressed, the resin layer can have excellent thermal properties such as moisture absorption and heat resistance, and high metal foil peel strength.

[0062] Therefore, the present inventors presume that, according to this embodiment, it is possible to obtain a cured product or the like that has a high dielectric constant, a low dielectric loss tangent, excellent thermal properties such as moisture absorption and heat resistance, and high metal foil peel strength, while also having excellent laser processability, although the reason is not limited to this.

[0063] Next, each component contained in the resin composition of this embodiment will be described in detail.

[0064] [Dielectric Powder (A)] The resin composition of this embodiment contains a dielectric powder (A) having a relative dielectric constant (Dk) of 12.0 or more at a frequency of 10 GHz measured according to a cavity resonator perturbation method. The dielectric powder (A) may be used singly or in combination of two or more.

[0065] The dielectric constant of the dielectric powder (A) is a value measured at a frequency of 10 GHz by a cavity resonator perturbation method. The dielectric constant of the dielectric powder (A) can be calculated using the Bruggeman formula (rule of mixtures). The dielectric constant can be measured, for example, as follows. That is, the dielectric powder (A) is packed into a PTFE (polytetrafluoroethylene) tube (inner diameter: 1.5 mm), and the dielectric constant of the dielectric powder (A) at a frequency of 10 GHz is measured using a network analyzer. Similarly, the dielectric constant of the PTFE tube at a frequency of 10 GHz is measured using a network analyzer. The dielectric constant of the dielectric powder (A) can be calculated from these measured values ​​using the Bruggeman formula (rule of mixtures). The dielectric constant is measured in an environment of a temperature of 23°C ± 1°C and a humidity of 50% RH (relative humidity) ± 5% RH. The specific method for measuring the dielectric constant is as described in the Examples.

[0066] The dielectric constant of the dielectric powder (A) is preferably 13.0 or more, more preferably 15.0 or more. When the dielectric constant is 13.0 or more, an insulating layer having a higher dielectric constant tends to be obtained. The upper limit of the dielectric constant is not particularly limited, but is, for example, 100.0 or less. The upper limit of the dielectric constant may be 90.0 or less, 80.0 or less, 70.0 or less, 60.0 or less, 50.0 or less, 40.0 or less, or 30.0 or less.

[0067] The dielectric loss tangent (Df) of the dielectric powder (A) at a frequency of 10 GHz measured according to a cavity resonator perturbation method is preferably 0.015 or less, more preferably 0.010 or less, and even more preferably 0.008 or less. If the dielectric loss tangent is 0.015 or less, an insulating layer having a lower dielectric loss tangent tends to be obtained. The lower limit of the dielectric loss tangent is not particularly limited, but is, for example, 0.001 or more.

[0068] The dielectric loss tangent of the dielectric powder (A) can be measured and calculated in the same manner as the relative dielectric constant of the dielectric powder (A). The specific method for measuring the dielectric loss tangent is as described in the Examples.

[0069] The average particle diameter (D50) of the dielectric powder (A) is preferably 0.10 μm or more and 10.00 μm or less, more preferably 0.15 μm or more and 8.00 μm or less, and even more preferably 0.20 μm or more and 7.50 μm or less, in order to obtain better dispersibility. In this specification, the average particle diameter (D50) refers to the value obtained when the particle size distribution of a predetermined amount of powder introduced into a dispersion medium is measured using a laser diffraction / scattering particle size distribution analyzer, and the volume of the smallest particles is integrated to reach 50% of the total volume. The average particle diameter (D50) can be calculated by measuring the particle size distribution using a laser diffraction / scattering method, and the specific measurement method is as described in the Examples.

[0070] In the infrared absorption spectrum of the dielectric powder (A) obtained using the KBr tablet method of Fourier transform infrared spectroscopy, the absorbance at a wavelength of 9.3 μm is preferably 0.70 or less, more preferably 0.60 or less, and even more preferably 0.50 or less. The lower limit of the absorbance is not particularly limited, but is 0.00 or more. Specific methods for measuring the absorbance are as described in the Examples.

[0071] The melting point of the dielectric powder (A) is preferably 1000°C or higher, more preferably 1000°C or higher and 2500°C or lower, even more preferably 1200°C or higher and 2300°C or lower, and even more preferably 1300°C or higher and 2200°C or lower. A melting point within the above range tends to result in a resin composition suitable for use in the manufacture of insulating layers for printed wiring boards, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, and higher metal foil peel strength, while also exhibiting excellent laser processability. The melting point of the dielectric powder (A) can be measured, for example, by simultaneous differential thermal analysis and thermogravimetry. Specific methods for measuring the melting point are as described in the Examples.

[0072] The shape of the dielectric powder (A) is not particularly limited, and examples thereof include flaky, spherical, plate-like, and amorphous shapes. The shape is preferably spherical, since this tends to result in a resin composition that is more easily dispersed in the thermosetting resin (C), has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and is suitable for use in producing an insulating layer of a printed wiring board.

[0073] (Titanium-based inorganic filler) The dielectric powder (A) preferably contains a titanium-based inorganic filler. The titanium-based inorganic filler preferably contains at least one selected from the group consisting of surface-uncoated titanium-based inorganic fillers and surface-coated titanium-based inorganic fillers. When the dielectric powder (A) contains such a dielectric powder, it tends to produce a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board, having a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0074] (Surface-uncoated titanium-based inorganic filler) Examples of surface-uncoated titanium-based inorganic fillers include titanium monoxide (TiO), titanium dioxide (TiO ２ ), titanium dioxide (Ti ２ O ３ ), potassium titanate (e.g., K ２ Ti ４ O ９), calcium titanate (e.g., CaTiO ３ ), strontium titanate (e.g., SrTiO ３ ), barium titanate (e.g., BaTiO ３、 and BaTi ４ O ９ ), aluminum titanate (e.g., Al ２ O ３ TiO ２ ), and lead titanate (e.g., PbTiO ３ When the dielectric powder (A) contains such a dielectric powder, it tends to be possible to obtain a resin composition or the like which is suitably used for producing an insulating layer of a printed wiring board, having a higher dielectric constant and a lower dielectric loss tangent, and having better thermal properties such as better moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0075] The surface-uncoated titanium-based inorganic filler preferably contains at least one selected from the group consisting of calcium titanate, strontium titanate, and barium titanate, and even more preferably contains strontium titanate. When the dielectric powder (A) contains these dielectric powders, it tends to produce a resin composition suitable for use in producing insulating layers for printed wiring boards, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength. Furthermore, when the dielectric powder (A) contains strontium titanate, in addition to the above effects, it tends to have lower catalytic activity toward the thermosetting resin (C) and better moldability.

[0076] As the strontium titanate, known ones can be used, for example, mainly ABO ３ Strontium titanate includes oxides with a perovskite structure represented by (SrO) Ｘ TiO ２(0.9≦x<1.0, 1.0<x≦1.1). In this compound, a portion of Sr may be substituted with another metal element, such as at least one of La (lanthanum), Ba (barium), and Ca (calcium). In addition, in this compound, a portion of Ti may be substituted with another metal element, such as Zr (zirconium).

[0077] As the barium titanate, known ones can be used, for example, mainly ABO ３ Barium titanate includes oxides with a perovskite structure represented by the formula: ｍ TiO ２＋ｍ (0.995≦m≦1.010, 0.995≦Ba / Ti (molar ratio)≦1.010) may be contained. Another example of barium titanate is BaTi ４ O ９ Examples of suitable compounds include compounds having a structure represented by the formula: In these compounds, a portion of Ba may be substituted with another metal element, and examples of such metal elements include at least one of La (lanthanum), Sr (strontium), and Ca (calcium). In addition, in these compounds, a portion of Ti may be substituted with another metal element, and examples of such metal elements include Zr (zirconium).

[0078] As calcium titanate, known ones can be used, for example, mainly ABO ３ Calcium titanate includes oxides with a perovskite structure represented by the formula: ｍ TiO ２＋ｍThe compound may contain a compound having a structure represented by the formula (0.995≦m≦1.010, 0.995≦Ca / Ti (molar ratio)≦1.010). In this compound, a portion of Ca may be substituted with another metal element, and examples of such metal elements include at least one of La (lanthanum), Sr (strontium), and Ca (calcium). In addition, in this compound, a portion of Ti may be substituted with another metal element, and examples of such metal elements include Zr (zirconium).

[0079] Titanium dioxide preferably has a rutile or anatase crystal structure, and more preferably has a rutile crystal structure.

[0080] Commercially available products can be used as the surface-uncoated titanium-based inorganic filler. Examples of commercially available products include titanium dioxide, such as STT-30A and EC-300 manufactured by Titan Kogyo Co., Ltd., and AEROXIDE (registered trademark, hereinafter the same) TiO manufactured by Nippon Aerosil Co., Ltd. ２ T805 and AEROXIDE TiO ２ NKT90 (all trade names), etc.; barium titanate, such as BT-149 (trade names) manufactured by Nippon Chemical Industry Co., Ltd. and 208108 (all trade names) manufactured by ALDRICH; calcium titanate, such as CT series manufactured by Fuji Titanium Industry Co., Ltd. and spherical calcium titanate (trade names) manufactured by Denka Co., Ltd.; strontium titanate, such as ST-2 manufactured by Kyoritsu Material Co., Ltd., ST-03 manufactured by Sakai Chemical Industry Co., Ltd., A Examples of titanium dioxide include 396141 manufactured by LDRICH Corporation, ST, HST-1, HPST-1, and HPST-2 manufactured by Fuji Titanium Industry Co., Ltd., and SW-100, SW-50C, SW-100C, SW-200C, SW-320C, and SW-350 (all trade names) manufactured by Titanium Industry Co., Ltd.; and titanium trioxide includes STR-100A-LP manufactured by Sakai Chemical Industry Co., Ltd. and MT-N1 (all trade names) manufactured by Teika Corporation.

[0081] (Surface-coated titanium-based inorganic filler) The surface-coated titanium-based inorganic filler preferably has an organic layer and / or an inorganic oxide layer on the surface of the titanium-based inorganic filler that forms the core of the surface-coated titanium-based inorganic filler. The surface-coated titanium-based inorganic filler may be used alone or in combination of two or more types of surface-coated titanium-based inorganic fillers with different particle sizes or surface conditions.

[0082] Examples of the titanium-based inorganic filler that serves as the core include the above-mentioned surface-uncoated titanium-based inorganic filler.

[0083] For the organic layer and inorganic oxide layer, reference can be made to the organic layer and inorganic oxide layer described in the section on surface-coated titanium oxide below.

[0084] The average particle diameter (D50) of the titanium-based inorganic filler that serves as the core is preferably 0.10 μm or more and 10.00 μm or less, more preferably 0.15 μm or more and 8.00 μm or less, and even more preferably 0.20 μm or more and 7.50 μm or less, from the viewpoint of dispersibility. The average particle diameter (D50) of the titanium-based inorganic filler is determined from the average particle diameter of the primary particles of a single particle.

[0085] <Surface-coated titanium oxide> The surface-coated titanium-based inorganic filler preferably contains surface-coated titanium oxide. The surface-coated titanium oxide preferably has an organic layer and / or an inorganic oxide layer on the surface of titanium oxide particles (hereinafter simply referred to as "titanium oxide particles" or "core particles") that form the core of the surface-coated titanium oxide. One type of surface-coated titanium oxide may be used alone, or two or more types of surface-coated titanium oxides with different particle sizes or surface conditions may be used in combination.

[0086] The total amount (coating amount) of the organic layer and the inorganic oxide layer in the surface-coated titanium oxide is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 1.0% by mass or more and 8.0% by mass or less, and even more preferably 1.0% by mass or more and 4.0% by mass or less, relative to 100% by mass of the surface-coated titanium oxide. When the coating amount is within the above range, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0087] The content of titanium oxide in the surface-coated titanium oxide is preferably 90.0% by mass or more and 99.9% by mass or less, more preferably 92.0% by mass or more and 99.0% by mass or less, and even more preferably 96.0% by mass or more and 99.0% by mass or less, relative to 100% by mass of the surface-coated titanium oxide. When the content is within the above range, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0088] The core particles include titanium monoxide (TiO), titanium trioxide (Ti ２ O ３ ), and titanium dioxide (TiO ２ Among these, titanium dioxide is preferred. Titanium dioxide having a rutile or anatase crystal structure is preferred, and titanium dioxide having a rutile crystal structure is more preferred.

[0089] The average particle diameter (D50) of the core particles is preferably 0.10 μm or more and 0.45 μm or less, more preferably 0.15 μm or more and 0.25 μm or less, from the viewpoint of dispersibility. The average particle diameter (D50) of the core particles is determined from the average particle diameter of the primary particles of a single particle.

[0090] Surface-coated titanium oxide is usually obtained by coating the surface of core particles with an organic layer or an inorganic oxide layer using a surface treatment agent. The surface of the organic layer or inorganic oxide layer coated on the surface of the core particles may be further coated with an organic layer and / or an inorganic oxide layer using a surface treatment agent. Since there is a tendency to obtain resin compositions suitable for use in the manufacture of insulating layers for printed wiring boards, which have a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength, it is preferable that the surface-coated titanium oxide further has an organic layer on the surface of the inorganic oxide layer coated on the surface of the core particles. Coating methods include inorganic treatment and organic treatment. One type of surface treatment agent may be used alone, or two or more types may be used in combination.

[0091] Examples of surface treatment agents used in the inorganic treatment include oxoacids (e.g., silicic acid and aluminic acid), metal salts of oxoacids (e.g., sodium silicate and sodium aluminate), oxides, hydroxides, and hydrated oxides of metals such as aluminum, silicon, zirconium, tin, titanium, antimony, zinc, cobalt, and manganese. The surface-coated titanium oxide obtained by the inorganic treatment has an inorganic oxide layer on the surface of the titanium oxide particles, the surface of the inorganic oxide layer, or the surface of the organic layer described below.

[0092] Examples of surface treatment agents used in the organic treatment include organosilicon compounds such as organosilanes, silane coupling agents, and organopolysiloxanes; organotitanium compounds such as titanium coupling agents; and organic substances such as organic acids, polyols, and alkanolamines. The surface-coated titanium oxide obtained by the organic treatment has an organic layer on the surface of the titanium oxide particles, the surface of the organic layer, or the surface of the inorganic oxide layer.

[0093] Examples of organosilanes include alkoxysilanes such as n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, 3-chloropropyltriethoxysilane, phenyltriethoxysilane, and trifluoropropyltrimethoxysilane.

[0094] Examples of the silane coupling agent include aminosilanes such as 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; epoxysilanes such as 3-glycidoxypropyltrimethoxysilane and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; methacrylsilanes such as 3-(methacryloyloxypropyl)trimethoxysilane; vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltrichlorosilane; and mercaptosilanes such as 3-mercaptopropyltrimethoxysilane.

[0095] Silicone oil is preferred as the organopolysiloxane because it can form a more uniform organic layer. Examples of silicone oils include alkyl silicones, alkyl hydrogen silicones, alkoxy silicones, and modified silicones. Examples of alkyl silicones include dimethyl silicone. Examples of alkyl hydrogen silicones include methyl hydrogen silicones and ethyl hydrogen silicones. Examples of alkoxy silicones include silicone compounds containing alkoxysilyl groups in which the alkoxy group is bonded to a silicon atom directly or via a divalent hydrocarbon group. Examples of such silicone compounds include linear, cyclic, network, and partially branched linear organopolysiloxanes. Among these, linear organopolysiloxanes are preferred, and organopolysiloxanes having a molecular structure in which the alkoxy group is directly bonded to the silicone main chain are more preferred. Examples of alkoxy silicones include methoxysilicone and ethoxysilicone. Examples of modified silicones include amino-modified silicones, epoxy-modified silicones, and mercapto-modified silicones.

[0096] Examples of titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl dimethacryl isostearoyl titanate, and isopropyl tridodecylbenzenesulfonyl titanate.

[0097] Examples of organic acids include adipic acid, terephthalic acid, lauric acid, myristic acid, palmitic acid, stearic acid, polyhydroxystearic acid, oleic acid, salicylic acid, malic acid, and maleic acid, as well as metal salts thereof.

[0098] Examples of polyols include trimethylolethane, trimethylolpropane, ditrimethylolpropane, trimethylolpropane ethoxylate, and pentaerythritol.

[0099] Examples of alkanolamines include monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, triethanolamine, and tripropanolamine.

[0100] Since a resin composition having good dispersibility with the thermosetting resin (C) and having better thermal properties such as moisture absorption and heat resistance upon curing, and better dielectric properties (high dielectric constant and low dielectric loss tangent), and further having a more suitable surface hardness, can be obtained, the surface-coated titanium oxide preferably has an inorganic oxide layer on the surface of titanium oxide particles, the inorganic oxide layer being one or more selected from the group consisting of a layer containing silica, a layer containing zirconia, and a layer containing alumina, and more preferably the inorganic oxide layer being one or more selected from the group consisting of a layer containing silica and a layer containing alumina. The use of such surface-coated titanium oxide tends to result in a resin composition that is more compatible with the thermosetting resin (C), has a higher dielectric constant and lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and is suitable for use in the production of insulating layers for printed wiring boards.

[0101] The surface-coated titanium oxide may have two or more inorganic oxide layers. When two or more inorganic oxide layers are present, it is preferable that the inorganic oxide layer located closer to the titanium oxide particles is mainly capable of further suppressing the water absorption of the titanium oxide particles (core particles), and the inorganic oxide layer located farther from the titanium oxide particles is mainly configured to further improve adhesion to the resin component, aggregation relaxation of the surface-coated titanium oxide in the resin composition, and dispersibility. From this perspective, when the surface-coated titanium oxide has two or more inorganic oxide layers, it is preferable that the inorganic oxide layer located closer to the core particles is one or more selected from the group consisting of a layer containing silica and a layer containing zirconia, and that the inorganic oxide layer located farther from the core particles is a layer containing alumina, and it is more preferable that the inorganic oxide layer located closer to the core particles is a layer containing silica and that the inorganic oxide layer located farther from the core particles is a layer containing alumina.

[0102] The content of the inorganic oxide layer is preferably 0.1% by mass or more and 10.0% by mass or less, more preferably 0.3% by mass or more and 7.5% by mass or less, even more preferably 0.4% by mass or more and 5.0% by mass or less, still more preferably 0.5% by mass or more and 4.0% by mass or less, and even more preferably 0.5% by mass or more and 3.3% by mass or less, relative to 100% by mass of the surface-coated titanium oxide. When the content is within the above range, a resin composition suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0103] The inorganic oxide layer has the effect of suppressing the water absorption of the titanium oxide core particles. On the other hand, the inorganic oxides constituting the inorganic oxide layer, such as silica, zirconia, and alumina, are hydrated inorganic substances and therefore have relatively high water absorption rates among inorganic oxides, and tend to evaporate moisture easily during reflow. The evaporated moisture causes voids to form in the insulating layer. For this reason, it is preferable that the surface-coated titanium oxide has an organic layer on the surface of the inorganic oxide layer. The organic layer further reduces the water absorption of the titanium oxide core particles and the inorganic oxide layer, and further suppresses the water absorption of the resin composition. Therefore, evaporation of moisture from the insulating layer during reflow can be suppressed. The organic layer also has the effect of further reducing aggregation of the surface-coated titanium oxide in the resin composition and further improving dispersibility.

[0104] The organic layer is preferably a layer surface-treated with an organosilicon compound, since this can further reduce the aggregation of the surface-coated titanium oxide in the resin composition, further improve dispersibility, and reduce the water absorption rate of the laminate due to its superior water repellency. The organosilicon compound preferably contains one or more compounds selected from the group consisting of silane coupling agents, organosilanes, and organopolysiloxanes. By performing surface treatment using these surface treatment agents, the resulting organic layer becomes a layer having a siloxane structure. A layer having a siloxane structure tends to further reduce the aggregation of the surface-coated titanium oxide in the resin composition, further improve dispersibility, and further reduce the water absorption rate of the laminate due to its superior water repellency. Furthermore, as the organopolysiloxane, silicone oil is preferred, since it can form a layer having a more uniform siloxane structure and further enhance the above-mentioned effects. Among silicone oils, dimethyl silicone is more preferred. In this case, surface treatment agents other than those mentioned above may be used as long as the organic layer becomes a layer having a siloxane structure.

[0105] Since this can further reduce aggregation of the surface-coated titanium oxide in the resin composition and further improve dispersibility, the organic layer preferably has a total content of 0.1 mass % or more and 10.0 mass % or less, more preferably 0.5 mass % or more and 7.5 mass % or less, even more preferably 0.6 mass % or more and 6.0 mass % or less, still more preferably 0.7 mass % or more and 5.0 mass % or less, and even more preferably 0.7 mass % or more and 3.5 mass % or less, relative to 100 mass % of the surface-coated titanium oxide.

[0106] When the surface-coated titanium oxide has an inorganic oxide layer and an organic layer, the coating layer of the surface-coated titanium oxide may have a two-layer structure consisting of an inorganic oxide layer and an organic layer. This layer structure suppresses the catalytic activity of titanium oxide (e.g., photocatalytic activity and metal catalytic activity) and provides water repellency. In this case, the inorganic oxide layer is preferably one or more selected from the group consisting of a layer containing silica, a layer containing zirconia, and a layer containing alumina. An alumina-containing layer is more preferred because it can further suppress the catalytic activity of titanium oxide while further enhancing affinity with resins. The organic layer preferably has a siloxane structure because of its excellent heat resistance and chemical stability. By using such surface-coated titanium oxide, the water absorption of titanium oxide can be further suppressed, adhesion to resin components can be further improved, and aggregation of the surface-coated titanium oxide in the resin composition can be further alleviated. As a result, there is a tendency to obtain a resin composition that is more compatible with the thermosetting resin (C), has a higher dielectric constant and a lower dielectric dissipation factor, and has better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and is suitable for use in producing insulating layers for printed wiring boards. Commercially available products can be used as such surface-coated titanium oxide. Examples of commercially available products include R-22L and R-11P (both trade names, Sakai Chemical Industry Co., Ltd.).

[0107] When the surface-coated titanium oxide has an inorganic oxide layer and an organic layer, it is preferable that the inorganic oxide layer located closest to the core particle is a layer containing silica, the next inorganic oxide layer is a layer containing alumina, and the organic layer located furthest from the core particle is a layer having a siloxane structure. The use of such surface-coated titanium oxide tends to result in a resin composition that is more compatible with the thermosetting resin (C), has a higher dielectric constant and a lower dielectric dissipation factor, and has better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and is suitable for use in the production of insulating layers for printed wiring boards. Commercially available products can be used as such surface-coated titanium oxide. An example of a commercially available product is CR-63 (trade name, Ishihara Sangyo Kaisha, Ltd.).

[0108] The mass ratio of the dielectric powder (A) to the inorganic filler (B) (dielectric powder (A): inorganic filler (B)) is preferably 300:10 to 300:150, more preferably 300:15 to 300:125, even more preferably 300:20 to 300:110, still more preferably 300:31 to 300:107, even more preferably 300:35 to 300:105, and even more preferably 300:40 to 300:100. When the mass ratio is within the above range, a resin composition suitable for use in the production of insulating layers for printed wiring boards tends to be obtained that has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0109] The content of the dielectric powder (A) is preferably 50 to 500 parts by mass, more preferably 60 to 450 parts by mass, and even more preferably 70 to 400 parts by mass, per 100 parts by mass of the total resin solids in the resin composition. When the content is within the above range, a resin composition suitable for use in the manufacture of insulating layers for printed wiring boards tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, and exhibits better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength. When the resin composition contains two or more types of dielectric powder (A), the total amount thereof is preferably within the above range.

[0110] [Inorganic Filler (B)] The resin composition of this embodiment contains an inorganic filler (B) having an absorbance of 0.70 or more at a wavelength of 9.3 μm in an infrared absorption spectrum obtained using Fourier transform infrared spectroscopy and a melting point of 1600° C. or less. The inorganic filler (B) is different from the dielectric powder (A). One type of inorganic filler (B) may be used alone, or two or more types may be used in combination.

[0111] The absorbance of the inorganic filler (B) was measured at a wavelength of 9.3 μm (wave number: 1075 cm ) in an infrared absorption spectrum obtained using the KBr tablet method of Fourier transform infrared spectroscopy. －１The specific method for measuring absorbance is as described in the Examples.

[0112] The absorbance of the inorganic filler (B) is preferably 0.72 or more, more preferably 0.75 or more. When the absorbance is within the above range, a resin composition suitable for use in the production of insulating layers of printed wiring boards tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption heat resistance, and higher metal foil peel strength, while also having excellent laser processability. The upper limit of the absorbance is not particularly limited, but is, for example, 1.00 or less.

[0113] The melting point of the inorganic filler (B) can be measured, for example, by simultaneous differential thermal analysis and thermogravimetry. The specific method for measuring the melting point is as described in the Examples.

[0114] The melting point of the inorganic filler (B) is preferably 1580°C or lower, more preferably 1560°C or lower. When the melting point is within the above range, a resin composition suitable for use in the production of insulating layers of printed wiring boards tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption heat resistance, higher metal foil peel strength, and furthermore has excellent laser processability. The lower limit of the melting point is not particularly limited, but is, for example, 800°C or higher. The lower limit may be 1000°C or higher.

[0115] The dielectric constant (Dk) of the inorganic filler (B) at a frequency of 10 GHz measured according to a cavity resonator perturbation method is preferably less than 12.0, more preferably 10.0 or less, even more preferably 8.0 or less, and still more preferably 7.0 or less. The lower limit of the dielectric constant is not particularly limited, but is, for example, 0.1 or more.

[0116] The dielectric loss tangent (Df) of the inorganic filler (B) at a frequency of 10 GHz measured according to a cavity resonator perturbation method is preferably 0.015 or less, more preferably 0.010 or less, and even more preferably 0.008 or less. When the dielectric loss tangent is 0.015 or less, an insulating layer having a lower dielectric loss tangent tends to be obtained. The lower limit of the dielectric loss tangent is not particularly limited, but is, for example, 0.001 or more.

[0117] The dielectric constant and dielectric loss tangent of the inorganic filler (B) can be measured and calculated in the same manner as the dielectric constant of the dielectric powder (A). Specific methods for measuring the dielectric constant and dielectric loss tangent are as described in the Examples.

[0118] The average particle size (D50) of the inorganic filler (B) is preferably 0.10 μm or more and 10.00 μm or less, more preferably 0.30 μm or more and 8.00 μm or less, and even more preferably 1.00 μm or more and 7.00 μm or less. The average particle size (D50) of the inorganic filler (B) can be measured and calculated in the same manner as the average particle size (D50) of the dielectric powder (A) described above. Specific measurement methods are as described in the Examples.

[0119] The shape of the inorganic filler (B) is not particularly limited, and examples thereof include flaky, spherical, plate-like, and amorphous shapes. The shape is preferably spherical, since this tends to result in a resin composition that is more favorably dispersed in the dielectric powder (A) and the thermosetting resin (C), has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and is suitable for use in producing an insulating layer for a printed wiring board.

[0120] The inorganic filler (B) preferably contains an alkaline earth metal silicate. When the inorganic filler (B) contains an alkaline earth metal silicate, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0121] Examples of alkaline earth metal silicates include compounds containing calcium silicate, compounds containing magnesium silicate, and compounds containing barium silicate. These alkaline earth metal silicates may have different crystal forms or may be hydrates. The alkaline earth metal silicate may contain two or more alkaline earth metals, such as a complex of calcium and magnesium.

[0122] The alkaline earth metal silicate preferably comprises a compound containing magnesium silicate, and more preferably comprises calcined talc.

[0123] Alkaline earth metal silicates include Mg ２ Si ２ O ６ It is preferable that the alkali metal silicate has the structure: Mg ２ Si ２ O ６ Alkaline earth metal silicates having the structure shown below are included in, for example, enstatite and clinoenstatite.

[0124] Calcined talc can usually be obtained by calcining raw material talc, for example, by heat treating it at a temperature of 900° C. or higher and 1500° C. or lower for 4 hours or longer and 10 hours or shorter. ３ Si ４ O １０ (OH) ２ Examples of the form of raw talc include hydrous magnesium silicate, such as a compound having the structure:

[0033] The raw talc may be in the form of, for example, a fine powder or a powder. When the raw talc is in the form of a powder, its average particle size (D50) is usually about 1.0 μm or more and 7.0 μm or less. Calcined talc is a compound containing Mg ２ Si ２ O ６ It is an alkaline earth metal silicate having the structure:

[0125] Commercially available calcined talc products can be used, such as BST-200L, CHT-125, ST-95, ST-100, and ST-2000 (all trade names, Nippon Talc Co., Ltd.), MS310 (trade name, Fuji Talc Kogyo Co., Ltd.), and Crown Talc (registered trademark) PP (trade name, Matsumura Sangyo Co., Ltd.).

[0126] The content of the inorganic filler (B) is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 15 parts by mass or more and 150 parts by mass or less, even more preferably 20 parts by mass or more and 125 parts by mass or less, even more preferably 40 parts by mass or more and 110 parts by mass or less, and even more preferably 30 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the total resin solid content in the resin composition. When the content is within the above range, a resin composition having a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, and suitable for use in the production of insulating layers of printed wiring boards tends to be obtained. When the resin composition contains two or more inorganic fillers (B), it is preferable that the total amount thereof is within the above range.

[0127] [Thermosetting resin (C)] The resin composition of the present embodiment contains a thermosetting resin (C). The thermosetting resin (C) is not particularly limited as long as it is a thermosetting resin or compound. The thermosetting resin (C) may be used alone or in combination of two or more.

[0128] The thermosetting resin (C) preferably contains one or more selected from the group consisting of maleimide compounds, cyanate ester compounds, epoxy compounds, phenolic compounds, modified polyphenylene ether compounds, alkenyl-substituted nadimide compounds, oxetane resins, benzoxazine compounds, and compounds having a polymerizable unsaturated group, more preferably one or more selected from the group consisting of maleimide compounds, cyanate ester compounds, phenolic compounds, and epoxy compounds, and even more preferably one or more selected from the group consisting of maleimide compounds, cyanate ester compounds, and epoxy compounds. When the thermosetting resin (C) contains the above resin or compound, the resulting resin composition tends to have a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, making it suitable for use in producing insulating layers for printed wiring boards.

[0129] The content of the thermosetting resin (C) in the resin composition is preferably 5 parts by mass or more and 90 parts by mass or less, more preferably 10 parts by mass or more and 80 parts by mass or less, even more preferably 15 parts by mass or more and 75 parts by mass or less, and even more preferably 20 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the total of the dielectric powder (A) and the inorganic filler (B). When the content of the thermosetting resin (C) is within the above range, the dielectric powder (A) and the inorganic filler (B) are more favorably dispersed, and a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained that has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0130] (Maleimide Compound) The resin composition of the present embodiment preferably contains a maleimide compound. When the thermosetting resin (C) contains a maleimide compound, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained that has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0131] The maleimide compound is not particularly limited, and any known compound having one or more maleimide groups in one molecule can be used as appropriate. The number of maleimide groups in one molecule of the maleimide compound is one or more, preferably two or more. The maleimide compounds may be used alone or in combination of two or more.

[0132] The maleimide compound is preferably a maleimide compound having an aromatic skeleton. Examples of such maleimide compounds include N-phenylmaleimide, N-hydroxyphenylmaleimide, bis(4-maleimidophenyl)methane, 2,2-bis(4-(4-maleimidophenoxy)-phenyl)propane, bis(3,5-dimethyl-4-maleimidophenyl)methane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, bis(3,5-diethyl-4-maleimidophenyl)methane, maleimide compounds represented by the following formula (1), maleimide compounds represented by the following formula (2), maleimide compounds represented by the following formula (3), and maleimide compounds represented by the following formula (4), prepolymers of these maleimide compounds, and prepolymers of the above maleimide compounds and amine compounds.

[0133] The maleimide compound more preferably includes at least one selected from the group consisting of bis(4-maleimidophenyl)methane, 2,2-bis(4-(4-maleimidophenoxy)-phenyl)propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, maleimide compounds represented by the following formula (1), maleimide compounds represented by the following formula (2), maleimide compounds represented by the following formula (3), and maleimide compounds represented by the following formula (4), and even more preferably includes at least one selected from the group consisting of bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, maleimide compounds represented by the following formula (2), maleimide compounds represented by the following formula (3), and maleimide compounds represented by the following formula (4). When the thermosetting resin (C) contains the maleimide compound, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric dissipation factor, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0134] It is even more preferable that the maleimide compound contains a maleimide compound represented by the following formula (2): When the thermosetting resin (C) contains the maleimide compound represented by formula (2), it tends to be possible to obtain a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board, which has a higher dielectric constant, in particular a lower dielectric loss tangent, and further excellent thermal properties such as moisture absorption heat resistance, further excellent laser processability, and further higher metal foil peel strength.

[0135]

[0136] In formula (1), R 1 each independently represents a hydrogen atom or a methyl group, and n1 is an integer of 1 to 10.

[0137]

[0138] In formula (2), R 2 each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group, and n2 represents an average value and satisfies 1<n2≦5.

[0139] Examples of the alkyl group having 1 to 5 carbon atoms include linear alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; and branched alkyl groups such as an isopropyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group.

[0140]

[0141] In formula (3), each Ra independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxy group, or a mercapto group. q represents an integer of 0 to 4. When q is an integer of 2 to 4, each Ra may be the same or different within the same ring. Each Rb independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. r represents an integer of 0 to 3. When r is 2 or 3, each Rb may be the same or different within the same ring. n3 is an average value of 0.95 to 10.0.

[0142] Examples of the alkyl group having 1 to 10 carbon atoms include, in addition to the alkyl groups having 1 to 5 carbon atoms exemplified above, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an isononyl group, and an n-decyl group.

[0143] Examples of the alkyloxy group having 1 to 10 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentyloxy group, and an n-hexyloxy group.

[0144] Examples of the alkylthio group having 1 to 10 carbon atoms include a methylthio group and an ethylthio group.

[0145] Examples of the aryl group having 6 to 10 carbon atoms include a phenyl group, a cyclohexylphenyl group, a phenol group, a cyanophenyl group, a nitrophenyl group, a naphthalene group, a biphenyl group, an anthracene group, a naphthacene group, an anthracyl group, a pyrenyl group, a perylene group, a pentacene group, a benzopyrene group, a chrysene group, a pyrene group, and a triphenylene group.

[0146] Examples of the aryloxy group having 6 to 10 carbon atoms include a phenoxy group and a p-tolyloxy group.

[0147] Examples of the arylthio group having 6 to 10 carbon atoms include a phenylthio group and a p-tolylthio group.

[0148] Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.

[0149] Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0150] In formula (3), it is preferred that each Ra is independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

[0151] In formula (3), q is preferably 2 or 3, and more preferably 2. The groups other than Ra directly bonded to the benzene ring are hydrogen atoms.

[0152] In formula (3), r is preferably 0. It is also preferable that r is an integer of 1 to 3, and each Rb is independently an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The groups other than Rb that are directly bonded to the benzene ring are hydrogen atoms.

[0153] The maleimide compound represented by formula (3) may be produced according to a known method. Specific examples of the production method include the method described in WO2020 / 217679.

[0154]

[0155] In formula (4), R １ each independently represents an alkyl group having 1 to 10 carbon atoms, and s represents an integer of 1 to 3. ２each independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. t represents an integer of 0 to 4. R ３ each independently represents a group represented by the following formula (5), and u represents an integer of 0 to 2. ４ represents a hydrogen atom or a group represented by the following formula (5): ５ represents a hydrogen atom or a group represented by the following formula (6): n4 represents an integer of 1 to 100.

[0156]

[0157] In formula (5), R ６ each independently represents an alkyl group, alkyloxy group, or alkylthio group having 1 to 10 carbon atoms, an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. v represents an integer of 0 to 4. *1 represents the bonding site to the carbon atom.

[0158]

[0159] In formula (6), R ７ Each independently represents an alkyl group having 1 to 10 carbon atoms. w represents an integer of 1 to 3. Each R8 independently represents a group represented by formula (5). x represents an integer of 0 to 2. *2 represents the bonding site with the carbon atom.

[0160] In formula (4), R １ Examples of the alkyl group having 1 to 10 carbon atoms in R include the alkyl groups having 1 to 10 carbon atoms exemplified above. １ is preferably an alkyl group having 1 to 6 carbon atoms. When s is an integer of 2 or more, R １ may be the same or different. １ is R １ is preferably bonded to at least one of the 2-, 3-, 4-, 5-, or 6-positions of the benzene ring to which R is bonded. １is preferably a methyl group, an ethyl group, or an n-propyl group. １ and R ３ For example, in formula (4), when s is 1 and u is 1, R directly bonded to the benzene ring is a hydrogen atom. １ and R ３ Groups other than the above represent hydrogen atoms.

[0161] In formula (4), s is preferably 1 or 2.

[0162] In formula (4), R ２ In formula (4), examples of the alkyl group having 1 to 10 carbon atoms, the alkyloxy group having 1 to 10 carbon atoms, the alkylthio group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, the aryloxy group having 6 to 10 carbon atoms, the arylthio group having 6 to 10 carbon atoms, the cycloalkyl group having 3 to 10 carbon atoms, and the halogen atom include the groups exemplified above. ２ are each independently preferably an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, or a hydroxy group, more preferably an alkyl group having 1 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms. ２ may be the same or different. ２ is preferably a methyl group, an ethyl group, or an n-propyl group. ２ The other groups are hydrogen atoms.

[0163] In formula (4), t is preferably 0, 1, or 2.

[0164] In formula (4), R ３ each independently represents a group represented by formula (5).

[0165] In formula (5), R ６In the above, examples of the alkyl group having 1 to 10 carbon atoms, the alkyloxy group having 1 to 10 carbon atoms, the alkylthio group having 1 to 10 carbon atoms, the aryl group having 6 to 10 carbon atoms, the aryloxy group having 6 to 10 carbon atoms, the arylthio group having 6 to 10 carbon atoms, the cycloalkyl group having 3 to 10 carbon atoms, and the halogen atom include the groups exemplified above and the halogen atom.

[0166] In formula (5), R ６ are each independently preferably an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, or a hydroxy group, more preferably an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and even more preferably an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms. When v is an integer of 2 or greater, R ６ may be the same or different. ６ The groups other than the above are hydrogen atoms.

[0167] In formula (5), v is preferably an integer of 0 to 3.

[0168] In formula (5), *1 indicates the bonding site to the carbon atom constituting the benzene ring.

[0169] In formula (4), u preferably represents 0 or 1.

[0170] In formula (4), R ４ represents a hydrogen atom or a group represented by formula (5), where formula (5) is as defined above.

[0171] In formula (4), R ５ represents a hydrogen atom or a group represented by formula (6).

[0172] In formula (6), R ７ The alkyl group having 1 to 10 carbon atoms in R １ The w in formula (6) is the same as the s in formula (4), including preferred embodiments.

[0173] In formula (6), each R8 independently represents a group represented by formula (5). The group represented by formula (5) is as described above. In formula (6), x is the same as u in formula (4), including preferred embodiments.

[0174] In formula (6), *2 represents -CH(CH ３ )- indicates the bonding position to the carbon atom in the group.

[0175] In formula (4), n4 preferably represents an integer of 1 to 90, and more preferably represents an integer of 1 to 80.

[0176] The weight-average molecular weight (Mw) of the maleimide compound represented by formula (4) is preferably 400 or more and 500,000 or less, more preferably 450 or more and 400,000 or less. The number-average molecular weight (Mn) of the maleimide compound represented by formula (4) is preferably 350 or more and 2,000 or less, more preferably 400 or more and 1,500 or less. The molecular weight distribution (Mw / Mn) of the maleimide compound represented by formula (4) is preferably 1.001 or more and 500 or less, more preferably 1.001 or more and 400 or less. In this specification, Mw, Mn, and Mw / Mn can be determined by gel permeation chromatography (GPC) using polystyrene standards.

[0177] The maleimide compound represented by formula (4) may be produced according to a known method, for example, the method described in JP-A-2023-7239.

[0178] The maleimide compound may be a commercially available product, or a product produced by a known method. Commercially available maleimide compounds include, for example, BMI-70 (bis(3-ethyl-5-methyl-4-maleimidophenyl)methane), BMI-80 (2,2-bis(4-(4-maleimidophenoxy)-phenyl)propane), and BMI-1000P (all trade names, manufactured by K.I. Chemical Co., Ltd.); BMI-3000, BMI-4000, BMI-5100, BMI-7000, and BMI-2300 (maleimide compounds represented by the above formula (1)) (all trade names, manufactured by Daiwa Chemical Industry Co., Ltd.); MIR-3000-70MT (trade name, manufactured by Daiwa Chemical Industry Co., Ltd.); ), available from Nippon Kayaku Co., Ltd.); NE-X-9470S (trade name, a maleimide compound represented by the above formula (3), in which Ra has two methyl groups (q=2) at the ortho positions relative to the N-maleimide group, all Rb's are hydrogen atoms (r=0), and n3 is an integer of 1 or more and 10 or less, available from DIC Corporation); and NE-X-9480S (trade name, a maleimide compound represented by the above formula (3), available from DIC Corporation); and NE-X-9500 (trade name, a maleimide compound represented by the above formula (4), available from DIC Corporation).

[0179] The content of the maleimide compound is preferably 15 to 85 parts by mass, more preferably 20 to 80 parts by mass, and even more preferably 25 to 75 parts by mass, per 100 parts by mass of the total resin solids in the resin composition. When the content of the maleimide compound is within the above range, a resin composition suitable for use in producing insulating layers of printed wiring boards tends to be obtained that has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength. When the resin composition contains two or more maleimide compounds, the total amount thereof is preferably within the above range.

[0180] (Cyanate ester compound) The resin composition of the present embodiment preferably contains a cyanate ester compound. When the thermosetting resin (C) contains a cyanate ester compound, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0181] Any known cyanate ester compound can be used as long as it has cyanato groups (hereinafter also referred to as "cyanate ester groups" or "cyanate groups") directly bonded to two or more aromatic rings in one molecule. One type of cyanate ester compound may be used alone, or two or more types may be used in combination.

[0182] Examples of cyanate ester compounds include phenol novolac type cyanate ester compounds, cresol novolac type cyanate ester compounds, naphthalene ring-containing novolac type cyanate ester compounds, allyl group-containing novolac type cyanate ester compounds, naphthol aralkyl type cyanate ester compounds, naphthylene ether type cyanate ester compounds, xylene resin type cyanate ester compounds, bisphenol M type cyanate ester compounds, bisphenol A type cyanate ester compounds, diallyl bisphenol A type cyanate ester compounds, bisphenol E type cyanate ester compounds, and bisphenol F type cyanate ester compounds. Examples of cyanate ester compounds include 4-cyanatophenyl ether, bis(4-cyanatophenyl)thioether, and bis(4-cyanatophenyl)sulfone. These cyanate ester compounds may be prepolymers or polymers of the cyanate ester compounds.

[0183] The cyanate ester compound preferably includes at least one selected from the group consisting of phenol novolac-type cyanate ester compounds, naphthol aralkyl-type cyanate ester compounds, naphthylene ether-type cyanate ester compounds, xylene resin-type cyanate ester compounds, bisphenol M-type cyanate ester compounds, bisphenol A-type cyanate ester compounds, diallyl bisphenol A-type cyanate ester compounds, bisphenol E-type cyanate ester compounds, bisphenol F-type cyanate ester compounds, and biphenyl aralkyl-type cyanate ester compounds, as well as prepolymers or polymers of these cyanate ester compounds; more preferably includes at least one selected from the group consisting of naphthol aralkyl-type cyanate ester compounds and bisphenol A-type cyanate ester compounds; and even more preferably includes a naphthol aralkyl-type cyanate ester compound. When the thermosetting resin (C) contains the above-mentioned cyanate ester compound, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric dissipation factor, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0184] The naphthol aralkyl cyanate ester compound is more preferably a compound represented by the following formula (7): When the thermosetting resin (C) contains the compound represented by formula (7), a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained, which has an even higher dielectric constant and an even lower dielectric loss tangent, even better thermal properties such as moisture absorption heat resistance, even better laser processability, and even higher metal foil peel strength.

[0185]

[0186] In formula (7), R ６ each independently represents a hydrogen atom or a methyl group, and among these, a hydrogen atom is preferred. In addition, in formula (7), n5 represents an integer of 1 or more, preferably an integer of 1 to 20, and more preferably an integer of 1 to 10.

[0187] The bisphenol A cyanate ester compound may be one or more selected from the group consisting of 2,2-bis(4-cyanatophenyl)propane and a prepolymer of 2,2-bis(4-cyanatophenyl)propane. Commercially available bisphenol A cyanate ester compounds may be used, such as Primaset (registered trademark) BADCy (trade name, Lonza Co., Ltd., 2,2-bis(4-cyanatophenyl)propane, cyanate ester group equivalent: 139 g / eq.) and CA210 (trade name, Mitsubishi Gas Chemical Company, Inc., 2,2-bis(4-cyanatophenyl)propane prepolymer, cyanate ester group equivalent: 139 g / eq.).

[0188] These cyanate ester compounds may be produced according to known methods, such as those described in JP-A-2017-195334 (particularly paragraphs 0052 to 0057).

[0189] The content of the cyanate ester compound is preferably 1 part by mass to 65 parts by mass, more preferably 2 parts by mass to 60 parts by mass, even more preferably 3 parts by mass to 55 parts by mass, even more preferably 4 parts by mass to 50 parts by mass, even more preferably 5 parts by mass to 45 parts by mass, and even more preferably 6 parts by mass to 40 parts by mass, based on 100 parts by mass of the total resin solids in the resin composition. When the content of the cyanate ester compound is within the above range, the resulting resin composition tends to have a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength, making it suitable for use in producing insulating layers for printed wiring boards. When the resin composition contains two or more cyanate ester compounds, it is preferable that the total amount thereof be within the above range.

[0190] (Epoxy Compound) The resin composition of the present embodiment preferably contains an epoxy compound. When the thermosetting resin (C) contains an epoxy compound, a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board tends to be obtained that has a higher dielectric constant and a lower dielectric loss tangent, and has better thermal properties such as moisture absorption heat resistance, better laser processability, and higher metal foil peel strength.

[0191] The epoxy compound is not particularly limited, and any known compound having one or more epoxy groups in one molecule can be used as appropriate. The number of epoxy groups in one molecule of the epoxy compound is one or more, preferably two or more. The epoxy compounds may be used alone or in combination of two or more.

[0192] As the epoxy compound, conventionally known epoxy compounds and epoxy resins can be used. For example, biphenylaralkyl type epoxy resins, naphthalene type epoxy resins, bisnaphthalene type epoxy resins, polyfunctional phenol type epoxy resins, naphthylene ether type epoxy resins, butadiene skeleton-containing epoxy resins, phenolaralkyl type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, xylene novolac type epoxy resins, naphthalene skeleton-modified novolac type epoxy resins, dicyclopentadiene novolac type epoxy resins, biphenyl novolac type epoxy resins, phenolaralkyl novolac type epoxy resins, naphtholaralkyl novolac type epoxy resins, aralkyl novolac type epoxy resins, aromatic hydrocarbon formaldehyde type epoxy compounds, anthraquinone type epoxy compounds, anthracene type epoxy resins, Examples of epoxy resins include epoxy resins, naphthol aralkyl epoxy compounds, dicyclopentadiene epoxy resins, Xylok epoxy compounds, bisphenol A epoxy resins, bisphenol E epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol A novolac epoxy resins, phenol epoxy compounds, biphenyl epoxy resins, aralkyl novolac epoxy resins, triazine skeleton epoxy compounds, triglycidyl isocyanurate, alicyclic epoxy resins, polyol epoxy resins, glycidyl amine, glycidyl ester resins, compounds in which the double bond of a double bond-containing compound such as butadiene has been epoxidized, and compounds obtained by reacting hydroxy group-containing silicone resins with epichlorohydrin.

[0193] The epoxy compound preferably contains at least one selected from the group consisting of biphenylaralkyl epoxy resins, naphthalene epoxy resins, naphthylene ether epoxy resins, and butadiene skeleton-containing epoxy resins, more preferably at least one selected from the group consisting of naphthalene epoxy resins and biphenylaralkyl epoxy resins, and even more preferably a biphenylaralkyl epoxy resin. When the thermosetting resin (C) contains the above epoxy resin, a resin composition suitable for use in producing an insulating layer for a printed wiring board tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength.

[0194] The biphenylaralkyl epoxy resin is preferably a compound represented by the following formula (8): When the thermosetting resin (C) contains the compound represented by formula (8), it tends to be possible to obtain a resin composition or the like that is suitable for use in producing an insulating layer of a printed wiring board, which has an even higher dielectric constant and an even lower dielectric loss tangent, even better thermal properties such as moisture absorption heat resistance, even better laser processability, and even higher metal foil peel strength.

[0195]

[0196] In formula (8), ka represents an integer of 1 or more, preferably an integer of 1 to 20, and more preferably an integer of 1 to 10.

[0197] The biphenylaralkyl epoxy resin may be a commercially available product or a product produced by a known method. Examples of commercially available products include NC-3000, NC-3000L, NC-3000H, and NC-3000FH (compounds represented by the above formula (8), where k is an integer of 1 to 10) (all trade names, Nippon Kayaku Co., Ltd.).

[0198] The naphthalene-type epoxy resin is preferably a compound represented by the following formula (9).

[0199]

[0200] In formula (9), R ３ｂ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms (e.g., a methyl group or an ethyl group), an aralkyl group, a benzyl group, a naphthyl group, a naphthyl group containing at least one glycidyloxy group, or a naphthylmethyl group containing at least one glycidyloxy group, and n represents an integer of 0 or more (e.g., 0 to 2).

[0201] A commercially available product of the compound represented by the above formula (9) is, for example, EPICLON (registered trademark) EXA-4032-70M (where n=0 and R ３ｂ are all hydrogen atoms), EPICLON (registered trademark) HP-4710 (in the above formula (9), n=0 and R ３ｂ naphthylmethyl group containing at least one glycidyloxy group) (all trade names, DIC Corporation).

[0202] The naphthylene ether type epoxy resin is preferably a bifunctional epoxy compound represented by the following formula (10) or a polyfunctional epoxy compound represented by the following formula (11), or a mixture thereof.

[0203]

[0204] In formula (10), R １３ each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms (for example, a methyl group or an ethyl group), or an alkenyl group having 2 to 3 carbon atoms (for example, a vinyl group, an allyl group, or a propenyl group).

[0205]

[0206] In formula (11), R １４ each independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms (for example, a methyl group or an ethyl group), or an alkenyl group having 2 to 3 carbon atoms (for example, a vinyl group, an allyl group, or a propenyl group).

[0207] The naphthylene ether type epoxy resin may be a commercially available product, or a product produced by a known method. Examples of commercially available products include HP-6000, EXA-7300, EXA-7310, EXA-7311, EXA-7311L, EXA7311-G3, EXA7311-G4, EXA-7311G4S, and EXA-7311G5 (all trade names, DIC Corporation). Among these, HP-6000 (trade name) is preferred.

[0208] The butadiene skeleton-containing epoxy resin may be any epoxy resin having a butadiene skeleton and an epoxy group in the molecule, such as butadiene skeleton-containing epoxy resins represented by the following formulas (12) to (14).

[0209]

[0210] In formula (12), X represents an integer of 1 to 100, and Y represents an integer of 0 to 100.

[0211]

[0212] In formula (13), R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, a and b each independently represent an integer of 1 to 100, and c and d each independently represent an integer of 0 to 100. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0213]

[0214] In formula (14), e represents an integer of 24 to 35, and f represents an integer of 8 to 11.

[0215] The butadiene skeleton-containing epoxy resin may be a commercially available product, or a product produced by a known method. Examples of commercially available products include R-15EPT and R-45EPT (compounds in which X = 50 and Y = 0 in the above formula (12)) (trade names, Nagase ChemteX Corporation); Epolead (registered trademark) PB3600 and PB4700 (trade names, Daicel Corporation); and Nisseki Polybutadiene E-1000-3.5 (trade name, Nippon Petrochemical Co., Ltd.).

[0216] The content of the epoxy compound is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 45 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the total resin solid content in the resin composition. When the content of the epoxy compound is within the above range, a resin composition suitable for use in the production of insulating layers of printed wiring boards tends to be obtained, which has a higher dielectric constant and a lower dielectric loss tangent, better thermal properties such as moisture absorption and heat resistance, better laser processability, and higher metal foil peel strength. When the resin composition contains two or more epoxy compounds, it is preferable that the total amount thereof is within the above range.

[0217] (Phenol Compound) The resin composition of the present embodiment may contain a phenol compound. Any known phenol compound may be used as long as it has two or more phenolic hydroxy groups in one molecule, and the type of phenol compound is not particularly limited. One type of phenol compound may be used alone, or two or more types may be used in combination.

[0218] Examples of the phenol compound include cresol novolac type phenolic resins, biphenyl aralkyl type phenolic resins represented by the following formula (15), naphthol aralkyl type phenolic resins represented by the following formula (16), aminotriazine novolac type phenolic resins, naphthalene type phenolic resins, phenol novolac resins, alkylphenol novolac resins, bisphenol A type novolac resins, dicyclopentadiene type phenolic resins, Zylok type phenolic resins, terpene-modified phenolic resins, and polyvinylphenols.

[0219] Among these, one or more selected from the group consisting of cresol novolac phenolic resins, biphenyl aralkyl phenolic resins represented by formula (15), naphthol aralkyl phenolic resins represented by formula (16), aminotriazine novolac phenolic resins, and naphthalene phenolic resins are preferred, as they provide excellent moldability and surface hardness, and one or more selected from the group consisting of biphenyl aralkyl phenolic resins represented by formula (15) and naphthol aralkyl phenolic resins represented by formula (16) are more preferred.

[0220]

[0221] In formula (15), R 4 each independently represents a hydrogen atom or a methyl group, and n4 is an integer of 1 to 10.

[0222]

[0223] In formula (16), R 5 each independently represents a hydrogen atom or a methyl group, and n5 is an integer of 1 to 10.

[0224] The content of the phenol compound is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 40 parts by mass or less, and even more preferably 10 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total resin solid content of the resin composition. When the content of the phenol compound is within the above range, the adhesiveness, flexibility, etc. tend to be better. When the resin composition contains two or more types of phenol compounds, it is preferable that the total amount thereof is within the above range.

[0225] (Modified Polyphenylene Ether Compound) The resin composition of the present embodiment may contain a modified polyphenylene ether compound. The modified polyphenylene ether compound is not particularly limited and any known compound may be used as long as some or all of the terminals of the polyphenylene ether compound are modified. In this specification, the term "modified" in the modified polyphenylene ether compound means that some or all of the terminals of the polyphenylene ether compound are substituted with reactive functional groups. Examples of reactive functional groups include groups having a carbon-carbon unsaturated double bond and hydroxy groups. The modified polyphenylene ether compounds may be used alone or in combination of two or more.

[0226] Examples of the polyphenylene ether compound related to the modified polyphenylene ether compound include a polymer containing at least one structural unit selected from the structural unit represented by formula (17), the structural unit represented by formula (18), and the structural unit represented by formula (19).

[0227]

[0228] In formula (17), R8, R9, R 10 , and R 11 each independently represents an alkyl group having 6 or less carbon atoms, an aryl group, a halogen atom, or a hydrogen atom.

[0229]

[0230] In formula (18), R 12 , R 13 , R 14 , R 18 , and R 19 R each independently represents an alkyl group having 6 or less carbon atoms or a phenyl group. 15 , R 16 , and R 17 each independently represents a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group.

[0231]

[0232] In formula (19), R 20 , R 21 , R 22 , R23 , R 24 , R 25 , R 26 , and R 27 each independently represents a hydrogen atom, an alkyl group having 6 or less carbon atoms, or a phenyl group. -A- represents a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms.

[0233] Examples of -A- in formula (19) include divalent organic groups such as a methylene group, an ethylidene group, a 1-methylethylidene group, a 1,1-propylidene group, a 1,4-phenylenebis(1-methylethylidene) group, a 1,3-phenylenebis(1-methylethylidene) group, a cyclohexylidene group, a phenylmethylene group, a naphthylmethylene group, and a 1-phenylethylidene group, but are not limited to these.

[0234] The modified polyphenylene ether compound is preferably, for example, a modified polyphenylene ether compound in which part or all of the terminals of the polyphenylene ether compound are modified with a functional group such as an ethylenically unsaturated group such as a vinylbenzyl group, an epoxy group, an amino group, a hydroxyl group, a mercapto group, a carboxy group, a methacryloyl group, or a silyl group.

[0235] Examples of modified polyphenylene ether compounds having hydroxyl groups at their terminals include SA90 (trade name, SABIC Innovative Plastics). Examples of modified polyphenylene ether compounds having methacryloyl groups at their terminals include SA9000 (trade name, SABIC Innovative Plastics).

[0236] The method for producing the modified polyphenylene ether compound is not particularly limited as long as it can achieve the effects of the present invention. For example, the compound can be produced by the method described in Japanese Patent No. 4,591,665.

[0237] The modified polyphenylene ether compound more preferably contains a modified polyphenylene ether compound having an ethylenically unsaturated group at its terminal. Examples of the ethylenically unsaturated group include alkenyl groups such as ethenyl, allyl, acryloyl, methacryloyl, propenyl, butenyl, hexenyl, and octenyl; cycloalkenyl groups such as cyclopentenyl and cyclohexenyl; and alkenylaryl groups such as vinylbenzyl and vinylnaphthyl. Among these, vinylbenzyl groups are preferred. The terminal ethylenically unsaturated groups may be single or multiple, and may be the same functional group or different functional groups.

[0238] The modified polyphenylene ether compound having an ethylenically unsaturated group at the terminal is preferably a compound represented by the following formula (20).

[0239]

[0240] In formula (20), X represents an aromatic group, and —(Y—O) ｍ - indicates a polyphenylene ether moiety. １ , R ２ , and R ３ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, or an alkynyl group, m represents an integer of 1 to 100, n represents an integer of 1 to 6, and q represents an integer of 1 to 4. m is preferably an integer of 1 to 50, more preferably an integer of 1 to 30. n is preferably an integer of 1 to 4, more preferably 1 or 2, and ideally 1. q is preferably an integer of 1 to 3, more preferably 1 or 2, and ideally 2.

[0241] Examples of the aromatic group represented by X in formula (20) include groups in which q hydrogen atoms have been removed from one ring structure selected from a benzene ring structure, a biphenyl ring structure, an indenyl ring structure, and a naphthalene ring structure (e.g., a phenylene group, a biphenylene group, an indenylene group, and a naphthylene group). Among these, a biphenylene group is preferred. Here, the aromatic group represented by X may include a diphenyl ether group in which an aryl group is bonded via an oxygen atom, a benzophenone group bonded via a carbonyl group, or a 2,2-diphenylpropane group bonded via an alkylene group. Furthermore, the aromatic group may be substituted with a common substituent such as an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms, particularly a methyl group), an alkenyl group, an alkynyl group, or a halogen atom. However, since the aromatic group is substituted on the polyphenylene ether moiety via an oxygen atom, the limit on the number of common substituents depends on the number of polyphenylene ether moieties.

[0242] As Y—O of the polyphenylene ether portion in formula (20), the structural unit represented by formula (17), the structural unit represented by formula (18), and the structural unit represented by formula (19) can be used. Among them, it is more preferable to contain the structural unit represented by formula (17).

[0243] Furthermore, in the modified polyphenylene ether compound represented by formula (20), the number average molecular weight is preferably 500 or more and 7000 or less. Furthermore, in formula (20), compounds having a minimum melt viscosity of 50,000 Pa·s or less can be used. In formula (20), the number average molecular weight is preferably 1,000 or more and 7,000 or less, and the minimum melt viscosity is more preferably 50,000 Pa·s or less. The number average molecular weight is measured using gel permeation chromatography according to a standard method. The number average molecular weight is preferably 1,000 or more and 3,000 or less. The minimum melt viscosity is measured using a dynamic viscoelasticity measuring device according to a standard method. The minimum melt viscosity is more preferably 500 Pa·s or more and 50,000 Pa·s or less.

[0244] As the modified polyphenylene ether compound, among those represented by formula (20), a compound represented by the following formula (21) is preferred.

[0245]

[0246] In formula (21), X is an aromatic group, -(Y-O) ｍ - and - (O-Y) ｍ "-" represents a polyphenylene ether moiety, and m represents an integer of 1 to 100. m is preferably an integer of 1 to 50, and more preferably an integer of 1 to 30. In formula (21), X and -(Y-O) ｍ - and m have the same meanings as in formula (20). -(O-Y) in formula (21) ｍ - represents -(Y-O) in formula (20). ｍ - is synonymous with.

[0247] X in the formula (20) and the formula (21) is the formula (22), the formula (23), or the formula (24), and -(Y-O) in the formula (20) and the formula (21) ｍ - and - (O-Y) ｍ - is preferably a structure in which formula (25) or formula (26) is arranged, or a structure in which formula (25) and formula (26) are arranged in blocks or randomly.

[0248]

[0249]

[0250] In formula (23), R 28 , R 29 , R 30 , and R 31 each independently represents a hydrogen atom or a methyl group. -B- represents a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms. Specific examples of -B- include the same as the specific examples of -A- in formula (19).

[0251]

[0252] In formula (24), -B- is a linear, branched, or cyclic divalent hydrocarbon group having 20 or less carbon atoms. Specific examples of -B- include the same as the specific examples of -A- in formula (19).

[0253]

[0254]

[0255] The method for producing a modified polyphenylene ether compound having a structure represented by formula (21) is not particularly limited, and the compound can be produced, for example, by vinylbenzyl etherifying the terminal phenolic hydroxyl groups of a bifunctional phenylene ether oligomer obtained by oxidative coupling of a bifunctional phenol compound with a monofunctional phenol compound. Furthermore, commercially available products such as OPE-2St1200 and OPE-2st2200 (both trade names, manufactured by Mitsubishi Gas Chemical Company, Inc.) can be used as modified polyphenylene ether compounds.

[0256] The content of the modified polyphenylene ether compound is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 40 parts by mass or less, and even more preferably 10 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total resin solid content in the resin composition. When the content of the modified polyphenylene ether compound is within the above range, low dielectric tangent and reactivity tend to be further improved. When the resin composition contains two or more modified polyphenylene ether compounds, it is preferable that the total amount thereof be within the above range.

[0257] (Alkenyl-substituted nadimide compound) The resin composition of the present embodiment may contain an alkenyl-substituted nadimide compound. The alkenyl-substituted nadimide compound is not particularly limited as long as it is a compound having one or more alkenyl-substituted nadimide groups in one molecule. The alkenyl-substituted nadimide compounds may be used alone or in combination of two or more.

[0258] Examples of the alkenyl-substituted nadimide compound include compounds represented by the following formula (27).

[0259]

[0260] In formula (27), each R1 independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms (for example, a methyl group or an ethyl group), and R2 represents an alkylene group having 1 to 6 carbon atoms, a phenylene group, a biphenylene group, a naphthylene group, or a group represented by formula (28) or formula (29).

[0261]

[0262] In formula (28), R3 represents a methylene group, an isopropylidene group, CO, O, S, or SO2.

[0263]

[0264] In formula (29), each R4 independently represents an alkylene group having 1 to 4 carbon atoms or a cycloalkylene group having 5 to 8 carbon atoms.

[0265] The alkenyl-substituted nadimide compound represented by formula (27) may be a commercially available product, or a product produced according to a known method. Commercially available products include BANI-M and BANI-X (trade names, Maruzen Petrochemical Co., Ltd.).

[0266] The content of the alkenyl-substituted nadimide compound is preferably 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the total resin solid content of the resin composition.

[0267] (Oxetane Resin) The resin composition of the present embodiment may contain an oxetane resin. The oxetane resin is not particularly limited, and generally known oxetane resins may be used. The oxetane resins may be used alone or in combination of two or more.

[0268] Examples of oxetane resins include alkyloxetanes such as oxetane, 2-methyloxetane, 2,2-dimethyloxetane, 3-methyloxetane, and 3,3-dimethyloxetane, 3-methyl-3-methoxymethyloxetane, 3,3-di(trifluoromethyl)perfluorooxetane, 2-chloromethyloxetane, 3,3-bis(chloromethyl)oxetane, biphenyl-type oxetane, OXT-101 (trade name, Toagosei Co., Ltd.), and OXT-121 (trade name, Toagosei Co., Ltd.).

[0269] The content of the oxetane resin is preferably 1 part by mass or more and 50 parts by mass or less relative to 100 parts by mass of the total resin solid content of the resin composition.

[0270] (Benzoxazine Compound) The resin composition of the present embodiment may contain a benzoxazine compound. The benzoxazine compound is not particularly limited as long as it is a compound having two or more dihydrobenzoxazine rings in one molecule, and generally known compounds can be used. The benzoxazine compounds may be used alone or in combination of two or more.

[0271] Examples of benzoxazine compounds include bisphenol A-type benzoxazine BA-BXZ, bisphenol F-type benzoxazine BF-BXZ, and bisphenol S-type benzoxazine BS-BXZ (all trade names, Konishi Chemical Industry Co., Ltd.).

[0272] The content of the benzoxazine compound is preferably 1 part by mass or more and 50 parts by mass or less relative to 100 parts by mass of the total resin solid content of the resin composition.

[0273] (Compound Having a Polymerizable Unsaturated Group) The resin composition of the present embodiment may contain a compound having a polymerizable unsaturated group. The compound having a polymerizable unsaturated group is not particularly limited, and generally known compounds can be used. The compound having a polymerizable unsaturated group may be used alone or in combination of two or more.

[0274] Examples of the compound having a polymerizable unsaturated group include vinyl compounds such as ethylene, propylene, styrene, divinylbenzene, and divinylbiphenyl; (meth)acrylates of monohydric or polyhydric alcohols such as methyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; epoxy(meth)acrylates such as bisphenol A type epoxy(meth)acrylate and bisphenol F type epoxy(meth)acrylate; and benzocyclobutene resins.

[0275] The content of the compound having a polymerizable unsaturated group is preferably 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the total resin solid content of the resin composition.

[0276] [Thermoplastic elastomer] The resin composition of the present embodiment may contain a thermoplastic elastomer. The thermoplastic elastomer is not particularly limited as long as it is a thermoplastic elastomer. The thermoplastic elastomer may be used alone or in combination of two or more.

[0277] Examples of the thermoplastic elastomer include styrene-based elastomers and other thermoplastic elastomers other than styrene-based elastomers.

[0278] Examples of styrene-based elastomers include styrene-butadiene random copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-hydrogenated butadiene-styrene block copolymers, styrene-hydrogenated isoprene-styrene block copolymers, styrene-butadiene block copolymers, styrene-isoprene block copolymers, styrene-hydrogenated butadiene block copolymers, styrene-hydrogenated isoprene block copolymers, and styrene-hydrogenated (isoprene / butadiene) block copolymers.

[0279] The styrene (styrene unit) in the polystyrene block structure may have a substituent, such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, and 4-cyclohexylstyrene.

[0280] The styrene content in the styrene elastomer is preferably 10% by mass or more, more preferably 20% by mass or more, based on 100% by mass of the styrene elastomer. The upper limit of the styrene content is, for example, less than 100% by mass, preferably less than 99% by mass, and more preferably 70% by mass or less. In this specification, the styrene content is a value expressed as (a) / (b)×100 (unit: mass%), where (a) is the mass of the styrene units contained in the styrene elastomer and (b) is the mass of the entire styrene elastomer.

[0281] As the styrene-based elastomer, commercially available products may be used, such as styrene-butadiene-styrene block copolymers such as TR2630 and TR2003 (trade names, manufactured by JSR Corporation), styrene-isoprene-styrene block copolymers such as SIS5250 (trade name, manufactured by JSR Corporation), styrene-hydrogenated isoprene-styrene block copolymers such as SEPTON (registered trademark) 2104 (manufactured by Kuraray Co., Ltd.), and styrene-hydrogenated butadiene-styrene block copolymers such as H-1043 (trade name, manufactured by Asahi Kasei Corporation).

[0282] Examples of thermoplastic elastomers other than styrene-based elastomers include polyisoprene, polybutadiene, butyl rubber, ethylene propylene rubber, fluororubber, silicone rubber, hydrogenated compounds thereof, and alkyl compounds thereof.

[0283] The content of the thermoplastic elastomer is preferably 0.5 parts by mass or more and 30 parts by mass or less, more preferably 1 part by mass or more and 25 parts by mass or less, even more preferably 1 part by mass or more and 20 parts by mass or less, still more preferably 2 parts by mass or more and 15 parts by mass or less, and even more preferably 3 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total resin solid content of the resin composition. When the resin composition contains two or more types of thermoplastic elastomers, the total amount thereof is preferably within the above range.

[0284] [Other Fillers] The resin composition of this embodiment may further contain a filler (hereinafter simply referred to as "other fillers") different from the dielectric powder (A) and the inorganic filler (B). When the resin composition contains other fillers, the dispersibility of the dielectric powder (A) and the inorganic filler (B) with the thermosetting resin (C) tends to be better. Furthermore, when the resin composition contains other fillers, a cured product tends to be obtained that has better thermal properties such as moisture absorption and heat resistance, a high glass transition temperature, a low thermal expansion coefficient, low water absorption, and better dielectric properties (high dielectric constant and low dielectric dissipation factor). Furthermore, when the resin composition contains other fillers, an insulating layer tends to be obtained that has better metal foil peel strength and more suitable surface hardness. The other fillers are not particularly limited as long as they are different from the dielectric powder (A) and the inorganic filler (B). The other fillers may be used alone or in combination of two or more.

[0285] The relative dielectric constant (Dk) of the other fillers at a frequency of 10 GHz measured according to the cavity resonator perturbation method is preferably less than 12.0, more preferably 10.0 or less, even more preferably 8.0 or less, and still more preferably 7.0 or less. The lower limit of the relative dielectric constant is not particularly limited, but is, for example, 0.1 or more.

[0286] The dielectric loss tangent (Df) of the other fillers at a frequency of 10 GHz measured according to the cavity resonator perturbation method is preferably 0.015 or less, more preferably 0.010 or less, and even more preferably 0.008 or less. When the dielectric loss tangent is 0.015 or less, an insulating layer having a lower dielectric loss tangent tends to be obtained. The lower limit of the dielectric loss tangent is not particularly limited, but is, for example, 0.001 or more.

[0287] The dielectric constants and dielectric loss tangents of other fillers can be measured and calculated in the same manner as the dielectric constant of the dielectric powder (A) described above. Specific methods for measuring the dielectric constant and dielectric loss tangent are as described in the Examples.

[0288] The other fillers have an absorbance at a wavelength of 9.3 μm in the infrared absorption spectrum obtained using the KBr tablet method of Fourier transform infrared spectroscopy, preferably less than 0.70, more preferably 0.60 or less. The lower limit of the absorbance is not particularly limited, but is 0.00 or more. The absorbance of the other fillers can be measured and calculated in the same manner as the inorganic filler (B) described above.

[0289] The melting point of the other filler is preferably above 1600°C, more preferably 1610°C or higher. The upper limit of the melting point of the other filler is, for example, 2500°C or lower. The melting point of the other filler can be measured, for example, by simultaneous differential thermal analysis and thermogravimetry. Specific methods for measuring the melting point are as described in the Examples.

[0290] The average particle diameter (D50) of the other fillers is preferably 0.10 μm or more and 10.00 μm or less, more preferably 0.30 μm or more and 5.00 μm or less. The average particle diameter (D50) of the other fillers can be measured and calculated in the same manner as the average particle diameter (D50) of the dielectric powder (A) described above.

[0291] Other fillers include, for example, silica, silicon compounds (e.g., white carbon, etc.), metal oxides (e.g., alumina), molybdenum compounds (e.g., molybdic acid, ZnMoO ４ and Zn ３ Mo ２ O ９Zinc molybdate, ammonium molybdate, sodium molybdate, potassium molybdate, calcium molybdate, molybdenum disulfide, molybdenum trioxide, molybdic acid hydrate, (NH ４ ) Zn ２ Mo ２ O ９ ・(H ３ ammonium zinc molybdate hydrate such as ammonium zinc oxide (MgO), zinc oxide, magnesium oxide, zirconium oxide, etc.), metal nitrides (for example, boron nitride, silicon nitride, aluminum nitride, etc.), metal sulfates (for example, barium sulfate, etc.), metal hydroxides (for example, aluminum hydroxide, heat-treated aluminum hydroxide (for example, aluminum hydroxide obtained by heat-treating aluminum hydroxide to remove some of the water of crystallization), boehmite, magnesium hydroxide, etc.), zinc compounds (for example, zinc borate, zinc stannate, etc.), clay, kaolin, talc other than calcined talc such as finely powdered talc and powdered talc, calcined clay, calcined kaolin, mica, E-glass, A-glass, NE-glass, C-glass, Examples of fillers include inorganic fillers such as L-glass, D-glass, S-glass, M-glass G20, short glass fibers (including glass fine powders such as E-glass, T-glass, D-glass, S-glass, and Q-glass), hollow glass, spherical glass, and metal fine particles that have been insulated from metals such as gold, silver, palladium, copper, nickel, iron, cobalt, zinc, Mn-Mg-Zn, Ni-Zn, Mn-Zn, carbonyl iron, Fe-Si, Fe-Al-Si, and Fe-Ni; and organic fillers such as styrene-type, butadiene-type, and acrylic-type rubber powders; core-shell-type rubber powders; silicone resin powders; silicone rubber powders; and silicone composite powders.

[0292] Among these, the other filler preferably includes at least one selected from the group consisting of silica, alumina, talc other than calcined talc such as fine powder talc and powdered talc, aluminum nitride, boron nitride, boehmite, aluminum hydroxide, zinc molybdate, silicone rubber powder, and silicone composite powder, and more preferably includes at least one selected from the group consisting of silica, talc other than calcined talc such as fine powder talc and powdered talc, and zinc molybdate. The silica preferably includes fused spherical silica. The alumina preferably includes spherical alumina.

[0293] The other filler may be a surface-treated filler in which an inorganic oxide is formed on at least a portion of the surface of a filler core particle, such as a surface-treated molybdenum compound particle (supported type) in which an inorganic oxide is formed on at least a portion of the surface of a core particle made of a molybdenum compound.

[0294] The inorganic oxide may be applied to at least a portion of the surface of the filler core particle. The inorganic oxide may be applied to a portion of the surface of the filler core particle, or may be applied so as to cover the entire surface of the filler core particle. It is preferable that the inorganic oxide is applied uniformly so as to cover the entire surface of the filler core particle, that is, a coating of the inorganic oxide is uniformly formed on the surface of the filler core particle.

[0295] Examples of the surface-treated molybdenum compound particles (supported type) include those obtained by surface-treating molybdenum compound particles with a silane coupling agent, and those obtained by treating the surface of the molybdenum compound particles with an inorganic oxide by a sol-gel method, a liquid-phase deposition method, or the like.

[0296] The inorganic oxide is preferably one having excellent heat resistance, and although the type is not particularly limited, metal oxides are more preferred. Examples of metal oxides include SiO ２ , Al ２ O ３ , TiO ２ , ZnO, In ２ O ３ , SnO ２ , NiO, CoO, V２ O ５ , CuO, MgO, and ZrO ２ These may be used alone or in appropriate combination of two or more. Among these, silica (SiO ２ ), titania (TiO ２ ), alumina (Al ２ O ３ ), and zirconia (ZrO ２ ) is preferably one or more selected from the group consisting of

[0297] The surface-treated molybdenum compound particles preferably have an inorganic oxide applied to at least a portion or all of the surface of a core particle made of a molybdenum compound, i.e., at least a portion or all of the periphery of the core particle.Among such surface-treated molybdenum compound particles, it is more preferred that silica be applied as an inorganic oxide to at least a portion or all of the surface of a core particle made of a molybdenum compound, i.e., at least a portion or all of the periphery of the core particle.The core particle made of a molybdenum compound is more preferably one or more selected from the group consisting of molybdic acid, zinc molybdate, and ammonium zinc molybdate hydrate.

[0298] The thickness of the inorganic oxide on the surface can be appropriately set depending on the desired performance and is not particularly limited. The thickness is preferably 3 nm or more and 500 nm or less, because a uniform inorganic oxide coating can be formed and adhesion to the filler core particles is superior.

[0299] From the viewpoint of dispersibility in the resin composition, the average particle size (D50) of the surface-treated molybdenum compound particles is 0.10 μm or more and 10.00 μm or less. The average particle size (D50) of the surface-treated molybdenum compound particles can be measured and calculated in the same manner as the average particle size (D50) of the dielectric powder (A) described above.

[0300] The core particles made of a molybdenum compound can be produced by various known methods such as a pulverization method or a granulation method, and the production method is not particularly limited. Commercially available products may also be used.

[0301] The method for producing the surface-treated molybdenum compound particles is not particularly limited, and the surface-treated molybdenum compound particles can be obtained by applying an inorganic oxide or a precursor thereof to the surface of core particles made of a molybdenum compound by appropriately employing, for example, various known methods such as a sol-gel method, a liquid phase deposition method, a dip coating method, a spray coating method, a printing method, an electroless plating method, a sputtering method, a vapor deposition method, an ion plating method, and a CVD method. The method for applying an inorganic oxide or a precursor thereof to the surface of core particles made of a molybdenum compound may be either a wet method or a dry method.

[0302] A suitable method for producing surface-treated molybdenum compound particles includes dispersing a molybdenum compound (core particles) in an alcohol solution containing a metal alkoxide such as silicon alkoxide (alkoxysilane) or aluminum alkoxide, adding a mixed solution of water, alcohol, and a catalyst dropwise while stirring to hydrolyze the alkoxide, thereby forming a low-refractive-index coating of silicon oxide or aluminum oxide on the surface of the compound, followed by solid-liquid separation of the resulting powder, vacuum drying, and heat treatment. Another suitable production method includes dispersing a molybdenum compound (core particles) in an alcohol solution containing a metal alkoxide such as silicon alkoxide or aluminum alkoxide, mixing under high temperature and low pressure to form a coating of silicon oxide or aluminum oxide on the surface of the compound, followed by vacuum drying and pulverization of the resulting powder. These methods can provide surface-treated molybdenum compound particles having a coating of a metal oxide such as silica or alumina on the surface of the molybdenum compound.

[0303] The content of the other filler is preferably 50 parts by mass or more and 300 parts by mass or less relative to 100 parts by mass of the total resin solid content in the resin composition. When the resin composition of the present embodiment contains two or more types of other fillers, the total amount is preferably within the above range.

[0304] [Silane Coupling Agent] The resin composition of this embodiment may contain a silane coupling agent. When the resin composition contains a silane coupling agent, the dispersibility of the dielectric powder (A), the inorganic filler (B), and other fillers that are added as needed is further improved, and the adhesive strength between each component contained in the resin composition and the substrate described below tends to be further improved. The silane coupling agent may be used alone or in combination of two or more.

[0305] The silane coupling agent is not particularly limited, and silane coupling agents generally used for surface treatment of inorganic substances can be used. Examples of such silane coupling agents include aminosilane compounds (e.g., 3-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, etc.), epoxysilane compounds (e.g., 3-glycidoxypropyltrimethoxysilane, etc.), acrylsilane compounds (e.g., γ-acryloxypropyltrimethoxysilane, etc.), vinylsilane compounds (e.g., vinyltrimethoxysilane, etc.), styrylsilane compounds (e.g., p-styryltrimethoxysilane, etc.), cationic silane compounds (e.g., N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, etc.), and phenylsilane compounds. Among these, the silane coupling agent is preferably one or more selected from the group consisting of epoxysilane compounds and styrylsilane compounds. Examples of epoxysilane compounds include "KBM-403" (trade name), "KBM-303" (trade name), "KBM-402" (trade name), and "KBE-403" (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. Examples of styrylsilane compounds include "KBM-1403" (trade name).

[0306] The content of the silane coupling agent is not particularly limited, but may be 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total resin solid content in the resin composition.

[0307] [Wetting and dispersing agent] The resin composition of this embodiment may contain a wetting and dispersing agent. When the resin composition contains a wetting and dispersing agent, the dispersibility of the dielectric powder (A), the inorganic filler (B), and other fillers added as needed is further improved, and the adhesive strength between each component contained in the resin composition and the substrate described below tends to be further improved. The wetting and dispersing agent may be used alone or in combination of two or more.

[0308] The wetting and dispersing agent may be a known dispersing agent (dispersion stabilizer) used to disperse fillers, such as DISPER BYK (registered trademark) -110, 111, 118, 140, 180, 161, 2009, 2055, 2152, 2155, W969, W996, W9010, and W903 (all trade names) manufactured by BYK Japan Co., Ltd.

[0309] The content of the wetting and dispersing agent is not particularly limited, but is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the total resin solid content in the resin composition.

[0310] [Curing Accelerator] The resin composition of the present embodiment may further contain a curing accelerator. The curing accelerator may be used alone or in combination of two or more.

[0311] Examples of the curing accelerator include imidazoles such as triphenylimidazole (for example, 2,4,5-triphenylimidazole); organic peroxides such as benzoyl peroxide, lauroyl peroxide, acetyl peroxide, parachlorobenzoyl peroxide, and di-tert-butyl-di-perphthalate; azo compounds such as azobisnitrile; N,N-dimethylbenzylamine, N,N-dimethylaniline, N,N-dimethyltoluidine, 2-N-ethylanilinoethanol, tri-n-butylamine, pyridine, quinoline, N-methylmorpholine, triethanolamine, triethylenediamine, tetramethyl Examples of suitable organic compounds include tertiary amines such as butanediamine and N-methylpiperidine; phenols such as phenol, xylenol, cresol, resorcinol, and catechol; organic metal salts such as lead naphthenate, lead stearate, zinc naphthenate, zinc octoate, manganese octoate, tin oleate, dibutyltin maleate, manganese naphthenate, cobalt naphthenate, and iron acetylacetonate; compounds obtained by dissolving these organic metal salts in hydroxyl-containing compounds such as phenol and bisphenol; inorganic metal salts such as tin chloride, zinc chloride, and aluminum chloride; and organic tin compounds such as dioctyltin oxide, other alkyltins, and alkyltin oxides. Among these, triphenylimidazoles such as 2,4,5-triphenylimidazole and manganese octoate are preferred because they accelerate the curing reaction and tend to further increase the glass transition temperature.

[0312] The content of the curing accelerator is not particularly limited, but may be 0.001 parts by mass or more and 2 parts by mass or less, or 0.01 parts by mass or more and 1 part by mass or less, relative to 100 parts by mass of the total resin solid content in the resin composition.

[0313] [Solvent] The resin composition of the present embodiment may further contain a solvent. By containing a solvent, the viscosity of the resin composition during preparation tends to decrease, the handleability (handling ability) of the resin composition is further improved, and the impregnation ability into the substrate tends to be further improved. The solvent may be used alone or in combination of two or more.

[0314] The solvent is not particularly limited as long as it can dissolve part or all of the components in the resin composition, and examples thereof include ketones (e.g., acetone, methyl ethyl ketone, etc.), aromatic hydrocarbons (e.g., toluene, xylene, etc.), amides (e.g., dimethylformaldehyde, etc.), propylene glycol monomethyl ether and its acetate, etc.

[0315] [Other Components] The resin composition of this embodiment may contain components other than those described above, provided that the intended properties are not impaired. Examples of other components include flame-retardant compounds such as bromine compounds such as 4,4'-dibromobiphenyl, nitrogen-containing compounds such as melamine and benzoguanamine, and silicon-based compounds. Various additives include ultraviolet absorbers, antioxidants, photopolymerization initiators, fluorescent brighteners, photosensitizers, dyes, pigments, thickeners, lubricants, antifoaming agents, dispersants, leveling agents (surface conditioners), gloss agents, and polymerization inhibitors.

[0316] The content of the other components is not particularly limited, but is usually 0.01 parts by mass or more and 10 parts by mass or less, respectively, per 100 parts by mass of the total resin solid content in the resin composition.

[0317] [Method for Producing Resin Composition] A method for producing the resin composition of this embodiment includes, for example, mixing and thoroughly stirring the dielectric powder (A), inorganic filler (B), thermosetting resin (C), and, if necessary, the above-described components. In this process, known processes such as stirring, mixing, and kneading can be performed to uniformly dissolve or disperse each component. Specifically, stirring and dispersing the components in a stirring tank equipped with a stirrer having appropriate stirring capabilities can improve the dispersibility of the dielectric powder (A), inorganic filler (B), and other fillers blended as needed in the resin composition. The stirring, mixing, and kneading processes can be performed appropriately using, for example, a mixing device such as a ball mill or a bead mill, or a known device such as a revolving or rotating mixer.

[0318] Furthermore, when preparing the resin composition, a solvent can be used as necessary to prepare a resin varnish. The resin varnish can be obtained by a known method. For example, the resin varnish can be obtained by adding 10 parts by mass or more and 900 parts by mass or less of an organic solvent to 100 parts by mass of the components in the resin composition excluding the organic solvent, and performing the known treatments (stirring, mixing, kneading treatment, etc.). The type of solvent is not particularly limited as long as it can dissolve the resin in the resin composition. Specific examples are as described above.

[0319] [Uses] The resin composition of the present embodiment can be suitably used, for example, as a raw material for cured products, prepregs, film-like underfill materials, resin sheets, laminates, build-up materials, non-conductive films, metal foil-clad laminates, printed wiring boards, and fiber-reinforced composite materials, or in the manufacture of semiconductor devices. The resin composition is suitably used for printed wiring boards. These uses will be described below.

[0320] [Cured Product] The cured product of this embodiment includes the resin composition of this embodiment. The cured product is obtained by curing the resin composition. The cured product can be produced, for example, by melting or dissolving the resin composition in a solvent (solvent), pouring the resultant into a mold, and curing it under normal conditions using heat, light, or the like. In the case of thermal curing, the curing temperature is preferably in the range of 120°C or higher and 300°C or lower, from the viewpoints of efficiently curing the product and preventing deterioration of the resulting cured product.

[0321] [Prepreg] The prepreg of this embodiment includes a substrate and the resin composition of this embodiment impregnated or coated on the substrate. The prepreg can be obtained, for example, by impregnating or coating the substrate with the resin composition (e.g., in an uncured state (A stage)) and then semi-curing (B stage) the substrate by, for example, heating and drying the composition at 120°C to 220°C for 2 to 15 minutes. In this case, the amount of the resin composition (including the cured resin composition) attached to the substrate, i.e., the amount of the resin composition (including the conductive powder (A), inorganic filler (B), and other fillers blended as needed) relative to the total amount of the semi-cured prepreg, is preferably in the range of 20% by mass to 99% by mass. The semi-cured state (B stage) refers to a state in which the components contained in the resin composition have not yet actively begun to react (cure), but the resin composition is in a dry state, i.e., the resin composition is heated to a non-tacky state to volatilize the solvent. It also includes a state in which the solvent has only volatilized without curing, even without heating. In this embodiment, the minimum melt viscosity in the semi-cured state (B-stage) is typically 20,000 Pa·s or less. The lower limit of the minimum melt viscosity is, for example, 10 Pa·s or more. In this embodiment, the minimum melt viscosity is measured by the following method. That is, 1 g of resin powder collected from the resin composition is used as a sample, and the minimum melt viscosity is measured using a rheometer (ARES-G2 (trade name), TA Instruments). Here, a disposable plate with a plate diameter of 25 mm is used, and the minimum melt viscosity of the resin powder is measured in the range of 40°C to 180°C under the conditions of a heating rate of 2°C / min, a frequency of 10.0 rad / sec, and a strain of 0.1%.

[0322] The substrate is not particularly limited as long as it is a substrate used in various printed wiring board materials. Examples of the substrate material include glass fiber (e.g., E-glass, D-glass, L-glass, S-glass, T-glass, Q-glass, UN-glass, and NE-glass), inorganic fibers other than glass fiber (e.g., quartz), and organic fibers (e.g., polyimide, polyamide, polyester, liquid crystal polyester, and polytetrafluoroethylene). The form of the substrate is not particularly limited, and examples include woven fabric, nonwoven fabric, roving, chopped strand mat, and surfacing mat. These substrates may be used alone or in combination of two or more. Among these substrates, woven fabrics that have been subjected to an ultra-opening treatment and a clogging treatment are preferred from the viewpoint of dimensional stability. Glass woven fabrics that have been surface-treated with a silane coupling agent, such as an epoxy silane treatment or an amino silane treatment, are preferred from the viewpoint of obtaining better processability and thermal properties such as moisture absorption and heat resistance. Glass fibers such as E-glass, L-glass, NE-glass, and Q-glass are preferred because they provide better processability and dielectric properties.

[0323] [Resin Sheet] The resin sheet of this embodiment includes the resin composition of this embodiment. The resin sheet may be a supported resin sheet including a support and a layer formed from the resin composition of this embodiment disposed on the surface of the support. The resin sheet can be used as a build-up film or a dry film solder resist. The method for producing the resin sheet is not particularly limited, but examples include a method of obtaining a resin sheet by applying (coating) a solution obtained by dissolving the resin composition in a solvent to a support and drying the applied solution.

[0324] Examples of the support include, but are not limited to, polyethylene film, polypropylene film, polycarbonate film, polyethylene terephthalate film, ethylene tetrafluoroethylene copolymer film, and release films obtained by applying a release agent to the surface of these films; organic film substrates such as polyimide film; metal foils such as copper foil and aluminum foil; glass plates, SUS plates, FRP, and other plate-shaped supports.

[0325] Examples of application methods (coating methods) include a method in which a solution obtained by dissolving a resin composition in a solvent is applied onto a support using a bar coater, die coater, doctor blade, baker applicator, or the like. Furthermore, after drying, a single-layer sheet (resin sheet) can be obtained by peeling or etching the support from a supported resin sheet in which the support and the resin composition are laminated. It should be noted that a single-layer sheet (resin sheet) can also be obtained without using a support by supplying a solution obtained by dissolving a resin composition in a solvent into a mold having a sheet-shaped cavity and drying it to form it into a sheet.

[0326] In the production of a single-layer sheet or a supported resin sheet, the drying conditions for removing the solvent are not particularly limited, but are preferably a temperature range of 20°C to 200°C and a drying time range of 1 minute to 90 minutes, from the viewpoint of facilitating removal of the solvent in the resin composition and suppressing the progress of curing during drying. Furthermore, in the single-layer sheet or supported resin sheet, the resin composition can be used in an uncured state after the solvent has been dried, or, if necessary, in a semi-cured (B-staged) state. Furthermore, the thickness of the resin layer of the single-layer sheet or supported resin sheet can be adjusted by the concentration and coating thickness of the resin composition solution, and is not particularly limited, but is preferably 0.1 μm to 500 μm, from the viewpoint of facilitating removal of the solvent during drying.

[0327] [Laminate] The laminate of this embodiment includes one or more selected from the group consisting of the prepreg and resin sheet of this embodiment. When two or more prepregs and resin sheets are laminated, the resin compositions used in each prepreg and resin sheet may be the same or different. When both a prepreg and a resin sheet are used, the resin compositions used therein may be the same or different. In the laminate, one or more selected from the group consisting of a prepreg and a resin sheet may be in a semi-cured state (B stage) or a completely cured state (C stage).

[0328] [Metal Foil-Clad Laminate] The metal foil-clad laminate of this embodiment includes the laminate of this embodiment and metal foil arranged on one or both sides of the laminate. The metal foil-clad laminate may also include at least one prepreg of this embodiment and metal foil laminated on one or both sides of the prepreg. Furthermore, the metal foil-clad laminate may also include at least one resin sheet of this embodiment and metal foil laminated on one or both sides of the resin sheet.

[0329] In a metal foil-clad laminate, the resin compositions used in each prepreg and resin sheet may be the same or different, and when both a prepreg and a resin sheet are used, the resin compositions used therein may be the same or different. In a metal foil-clad laminate, one or more selected from the group consisting of a prepreg and a resin sheet may be in a semi-cured state or a completely cured state.

[0330] In a metal foil-clad laminate, a metal foil is laminated on one or more materials selected from the group consisting of prepregs and resin sheets. It is particularly preferred that the metal foil be laminated so as to contact the surface of one or more materials selected from the group consisting of prepregs and resin sheets. "The metal foil is laminated so as to contact the surface of one or more materials selected from the group consisting of prepregs and resin sheets" means that the prepreg or resin sheet and the metal foil are in direct contact with each other, without the inclusion of any layer such as an adhesive layer between them. This increases the metal foil peel strength of the metal foil-clad laminate, and tends to improve the insulation reliability of printed wiring boards.

[0331] The metal foil-clad laminate may have one or more stacked prepregs and / or resin sheets and metal foils arranged on one or both sides of the prepregs and / or resin sheets. Examples of methods for producing metal foil-clad laminates include a method in which one or more prepregs and / or resin sheets are stacked and metal foils are arranged on one or both sides of the stacked prepregs and / or resin sheets to form a laminate. Examples of molding methods include methods commonly used for forming laminates and multilayer boards for printed wiring boards. More specifically, a multistage press, a multistage vacuum press, a continuous molding machine, an autoclave molding machine, or the like is used to form the laminate at a temperature of about 180°C to about 350°C, a heating time of about 100 minutes to about 300 minutes, and a surface pressure of 20 kgf / cm. ２ More than 100kgf / cm ２ Examples of the method include lamination molding at the following levels.

[0332] Alternatively, a multilayer board can be produced by laminating and molding a prepreg and / or resin sheet with a separately prepared inner layer wiring board. For example, a multilayer board can be produced by placing copper foil of approximately 1.5 μm to 70 μm thick on both sides of one or more stacked prepregs and / or resin sheets, laminating them using the above-mentioned molding method to form a copper foil-clad laminate, forming an inner layer circuit, blackening the circuit to form an inner layer circuit board, and then alternately arranging the inner layer circuit board and the prepreg and / or resin sheet one by one. Furthermore, copper foil is placed on the outermost layer, and the multilayer board can be produced by laminating and molding under the above-mentioned conditions, preferably under vacuum. The metal foil-clad laminate can be suitably used as a printed wiring board.

[0333] <Metal Foil> The metal foil is not particularly limited, and examples thereof include gold foil, silver foil, copper foil, tin foil, nickel foil, and aluminum foil. Among these, copper foil is preferred. The copper foil is not particularly limited as long as it is generally used as a material for printed wiring boards, and examples thereof include rolled copper foil and electrolytic copper foil. Among these, electrolytic copper foil is preferred from the viewpoint of copper foil peel strength and the ability to form fine wiring. The thickness of the copper foil is not particularly limited, and may be approximately 1.5 μm or more and 70 μm or less.

[0334] When copper foil is used as the metal foil, the copper foil preferably has a surface roughness Rz adjusted to 0.2 μm or more and 4.0 μm or less. When the surface roughness Rz of the copper foil is 0.2 μm or more, the surface roughness of the copper foil becomes appropriate, and the copper foil peel strength tends to be further improved. When the surface roughness Rz of the copper foil is 4.0 μm or less, the surface roughness of the copper foil becomes appropriate, and the dielectric loss tangent of the obtained cured product tends to be further improved. The roughness Rz is measured in accordance with JIS B0601:2013. Since the copper foil peel strength of the obtained cured product is further improved, the lower limit of the surface roughness Rz of the copper foil is more preferably 0.5 μm or more, even more preferably 0.6 μm or more, and even more preferably 0.7 μm or more. Furthermore, since the dielectric loss tangent of the resulting cured product is further improved, the upper limit of the roughness Rz of the copper foil surface is more preferably 3.5 μm or less, even more preferably 3.0 μm or less, and even more preferably 2.0 μm or less.

[0335] [Printed Wiring Board] The printed wiring board of this embodiment has an insulating layer and a conductor layer disposed on one or both sides of the insulating layer, and the insulating layer contains a cured product of the resin composition of this embodiment. The insulating layer preferably contains at least one of a layer formed from the resin composition (a layer containing a cured product) and a layer formed from a prepreg (a layer containing a cured product). Such a printed wiring board can be manufactured according to a conventional method, and the manufacturing method is not particularly limited, but it can be manufactured, for example, using the above-mentioned metal foil-clad laminate. An example of a method for manufacturing a printed wiring board is shown below.

[0336] First, the metal foil-clad laminate described above is prepared. Next, the surface of the metal foil-clad laminate is etched to form an inner layer circuit, producing an inner layer substrate. The inner layer circuit surface of this inner layer substrate is subjected to a surface treatment (surface roughening treatment) to increase adhesive strength, if necessary. Next, a required number of the above-described prepregs are stacked on the inner layer circuit surface, and a metal foil for an outer layer circuit is further laminated on the outside of the prepreg, and the resulting laminate is integrally molded by heating and pressurizing. In this manner, a multilayer laminate is produced in which an insulating layer composed of a substrate and a cured resin composition is formed between the inner layer circuit and the metal foil for the outer layer circuit. Next, this multilayer laminate is drilled for through holes and via holes. Thereafter, a metal plating treatment is performed to form a plated metal film on the wall of the hole, which electrically connects the inner layer circuit and the metal foil for the outer layer circuit. If necessary, the metal foil for the outer layer circuit is further etched to form the outer layer circuit, thereby producing a printed wiring board. After drilling for through holes and via holes, a roughening treatment, including a desmear treatment, is preferably performed.

[0337] The printed wiring board obtained in the above manufacturing example has an insulating layer and a conductor layer formed on the surface of the insulating layer, and the insulating layer is configured to contain a cured product of the resin composition. That is, the prepreg according to this embodiment (including a substrate and a cured product of the resin composition of this embodiment impregnated or applied thereto) and the resin composition layer of the metal foil-clad laminate according to this embodiment (a layer containing a cured product of the resin composition of this embodiment) are each composed of an insulating layer containing a cured product of the resin composition of this embodiment.

[0338] The resin composition of the present embodiment has a high dielectric constant and a low dielectric loss tangent, excellent thermal properties such as moisture absorption and heat resistance, and high metal foil peel strength, while also having excellent laser processability. Therefore, by using the resin composition, it is possible to obtain a printed wiring board having an insulating layer with higher insulation reliability, while having a high dielectric constant, a low dielectric loss tangent, excellent thermal properties such as moisture absorption and heat resistance, and high metal foil peel strength.

[0339] In the above production examples, examples of the surface roughening treatment method include a method using BO-220 (trade name, manufactured by Nippon McDermitt Co., Ltd.).

[0340] Drilling for through holes and via holes is usually performed to electrically connect inner layer circuits and outer layer circuits. A through hole is a hole that extends from a predetermined position on one surface of a laminate to the other surface of the laminate. A via hole is a hole that extends from a predetermined position on one surface of a laminate to an inner layer circuit without reaching the other surface of the laminate. The predetermined position refers to an appropriate position along the circuit pattern.

[0341] Through holes and via holes are usually filled with carbon dioxide (CO ２ Lasers, mechanical drills, ultraviolet lasers (UV lasers), and YAG lasers can be used for processing. Among these, carbon dioxide gas lasers are preferably used for drilling through holes and via holes because they can accurately process small diameter holes and are excellent in processing speed and cost.

[0342] The top diameters of the through holes and via holes may be different or the same and are not particularly limited. The top diameters of the through holes and via holes vary depending on the application, but are typically about 1.0 μm or more and 1000 μm or less. It is preferable that the top diameters are uniform, as this provides excellent mechanical strength and allows for the production of highly densely mounted substrates. In this specification, the top diameter refers to the outer diameter of each via hole located closest to the laser irradiation side.

[0343] Another advantage of the carbon dioxide laser is that it can appropriately form desired through holes and via holes by appropriately setting the laser wavelength, pulse width, total energy amount, and number of shots.

[0344] The laser wavelength of the carbon dioxide laser is usually 9.0 μm or more and 11.0 μm or less. The laser wavelength is preferably 9.3 μm, since this makes it difficult to gouge the hole wall surfaces of the laminate and results in a printed wiring board with better insulation reliability.

[0345] The pulse width of the carbon dioxide laser can be set appropriately depending on the laminate, but is usually 100 μsec or less. The pulse width is preferably 1.0 μsec or more and 20 μsec or less. When the pulse width is within the above range, a more precise hole shape tends to be obtained. In this specification, the pulse width means the half-width of the curve obtained using a single pulse laser. The pulse width has a time dimension and is a temporal width that indicates how long the light is emitted.

[0346] The total energy amount of the carbon dioxide laser per through hole or via hole is usually 0.1 mJ or more and 20 mJ or less, and preferably 0.5 mJ or more and 15 mJ or less. When the total energy amount is within the above range, a more precise hole shape tends to be obtained. In this specification, the total energy amount means the total energy amount of the laser input to the printed wiring board in one laser drilling.

[0347] The number of carbon dioxide laser shots per through-hole or via-hole is usually from 1 to 5, and from the standpoint of economy and processing time, preferably from 1 to 3.

[0348] Examples of methods for forming holes include trepanning and punching.

[0349] Trepanning is a processing method for drilling holes by applying energy along the contour of a hole having a certain shape. In other words, trepanning is a processing method for cutting the contour of a hole having a certain shape. Trepanning is preferably used for processing holes larger than the beam diameter. In trepanning, the number of shots per revolution is the number of times a single pulse laser is irradiated onto a printed wiring board during one revolution of scanning when processing a single hole by trepanning. In trepanning, the number of revolutions is the number of revolutions made along the contour of a hole when processing a single hole by trepanning.

[0350] Punching is a processing method in which a carbon dioxide laser is irradiated multiple times at the same location. Punching is suitable for drilling deep holes. In punching, the number of shots refers to the number of times the carbon dioxide laser is irradiated onto a printed wiring board when drilling a single hole by punching.

[0351] In order to remove resin residue remaining on the side surfaces of the formed through-holes and via-holes, it is preferable to carry out a roughening treatment including a desmear treatment after the drilling process.

[0352] Generally, the roughening treatment includes a swelling step, a surface roughening and smear dissolving step, and a neutralization step.

[0353] The swelling step is a step of swelling the surface of the insulating layer using a swelling agent. Examples of the swelling agent include those that can improve the wettability of the surface of the insulating layer and swell the surface of the insulating layer to an extent that oxidative decomposition is promoted in the subsequent surface roughening and smear dissolution steps. Examples of such swelling agents include alkaline solutions and surfactant solutions.

[0354] The surface roughening and smear dissolving process is a process carried out using an oxidizing agent. Examples of the oxidizing agent include an alkaline permanganate aqueous solution. Preferred examples of such aqueous solutions include a potassium permanganate aqueous solution and a sodium permanganate aqueous solution. Such an oxidizing agent treatment is usually called wet desmearing, but in addition to wet desmearing, other known roughening treatments such as dry desmearing by oxygen plasma treatment, corona discharge treatment, ultraviolet (UV) laser treatment, and excimer laser treatment, mechanical polishing by buffing, and sandblasting may be appropriately combined.

[0355] The neutralization step is a step of neutralizing the oxidizing agent used in the previous step with a reducing agent. Examples of the reducing agent include amine-based reducing agents. Preferred examples of the reducing agent include acidic aqueous solutions of hydroxylamine sulfate, ethylenediaminetetraacetic acid, and nitrilotriacetic acid.

[0356] After the through holes and / or via holes are formed or after the interiors of the through holes and / or via holes are roughened, it is preferable to carry out a metal plating treatment, which is a treatment for forming a plated metal film for electrically connecting the respective conductor layers.

[0357] As the metal plating method, a metal plating method used in the manufacture of a normal multilayer printed wiring board can be appropriately used. As the metal plating method and the type of chemical solution used for plating, a metal plating method and chemical solution used in the manufacture of a normal multilayer printed wiring board can be appropriately used. The chemical solution used for the metal plating may be a commercially available product.

[0358] Examples of such metal plating methods include a method in which the following steps are performed in this order: treatment with a conditioner solution (degreasing solution), water washing, treatment with a pre-dip solution (soft etching solution), treatment with an electroless plating catalyst solution (activator solution), water washing, treatment with an electroless plating solution (e.g., electroless copper plating solution), and treatment of immersion in a copper sulfate solution and passing an electric current through it (copper sulfate electroplating).

[0359] After the treatment of immersion in a copper sulfate solution and passing an electric current, the substrate may be dried, typically at a temperature of 130° C. to 220° C. for 10 minutes to 120 minutes.

[0360] [Semiconductor Device] A semiconductor device can be manufactured by mounting a semiconductor chip on the conductive portion of the printed wiring board of this embodiment. Here, the conductive portion refers to a portion of the multilayer printed wiring board that transmits an electrical signal, and the conductive portion may be located on the surface or in an embedded portion. Furthermore, the semiconductor chip is not particularly limited as long as it is an electrical circuit element made of a semiconductor material.

[0361] The method for mounting a semiconductor chip when manufacturing a semiconductor device is not particularly limited as long as the semiconductor chip functions effectively, but specific examples include a wire bonding mounting method, a flip chip mounting method, a bumpless build-up layer (BBUL) mounting method, an anisotropic conductive film (ACF) mounting method, and a non-conductive film (NCF) mounting method.

[0362] The present embodiment will be described in more detail below using examples and comparative examples, but the present embodiment is not limited to the following examples.

[0363] [Measurement Method] (1) Relative Permittivity (Dk) and Dielectric Loss Tangent (Df) The relative permittivity (Dk) and dielectric loss tangent (Df) of the dielectric powders (strontium titanate, spherical calcium titanate, surface-coated titanium oxide, and barium titanate) and the inorganic fillers (calcined talc, fused spherical silica, spherical alumina, finely powdered talc, and boehmite) were measured by a cavity resonator perturbation method as follows. First, a measurement sample (S) was obtained by packing 200 mg of the dielectric powder into a PTFE (polytetrafluoroethylene) tube (inner diameter: 1.5 mm, manufactured by Nichias Corporation). The relative permittivity (Dk) and dielectric loss tangent (Df) of this measurement sample (S) at a frequency of 10 GHz were measured using a network analyzer (Agilent 8722ES (trade name), manufactured by Agilent Technologies, Inc.). The measurements of the dielectric constant (Dk) and the dielectric loss tangent (Df) were carried out in an environment of a temperature of 23°C ± 1°C and a humidity of 50% RH (relative humidity) ± 5% RH. Similarly, a PTFE (polytetrafluoroethylene) tube (inner diameter: 1.5 mm, manufactured by Nichias Corporation) itself was used as sample (B) and used as a blank to measure the dielectric constant (Dk) and the dielectric loss tangent (Df) at a frequency of 10 GHz for this sample (B). From these measurement results, the dielectric constant (Dk) and the dielectric loss tangent (Df) of the dielectric powder at 10 GHz were calculated using the following Bruggeman formula (ii). Formula (ii): f ａ × [(ε ａ -ε ｄ ) / (ε ａ +2ε ｄ ) ]+f ｂ × [(ε ｂ -ε ｄ ) / (ε ｂ +2ε ｄ ) ]+f ｃ × [(ε ｃ -ε ｄ ) / (ε ｃ +2ε ｄ) )]=0 Note that f in formula (ii) ａ is the volume fraction (vol%) of PTFE in the measurement sample, f ｂ is the volume fraction of air in the measurement sample (vol%), f ｃ is the volume fraction (vol%) of the dielectric powder in the measurement sample, ε ａ is the complex dielectric constant of PTFE, ε ｂ is the complex permittivity of air, ε ｃ is the complex permittivity of the dielectric powder, ε ｄ is the complex dielectric constant of the measurement sample. Specifically, first, in sample (B), the volume fraction of air f ｂＢ 46 (vol%), PTFE volume fraction f ａＢ The complex dielectric constant is expressed by a real part and an imaginary part, such as "ε = ε' - iε"," where Dk is expressed as ε' and Df is expressed as ε" / ε'. Therefore, the complex dielectric constant ε of sample (B) (containing PTFE and air) can be calculated from the measurement results (Dk and Df) of sample (B). ｄＢ Next, the complex permittivity of air, ε ｂＢ is 1.0 assuming that the real part is 1.0 and the imaginary part is 0, so f ａＢ , f ｂＢ , ε ｄＢ , and ε ｂＢ By substituting into equation (ii), the complex dielectric constant ε of PTFE is ａ Next, the volume fraction f of the dielectric powder in the measurement sample (S) (containing PTFE, air, and dielectric powder) was calculated. ｃＳ The volume fraction f of PTFE (vol%) was calculated using the inner diameter and length of the PTFE tube, the mass difference before and after filling with the dielectric powder, and the specific gravity of the dielectric powder. ａＳ is assumed to be 54 (vol%), and the calculated volume fraction f ｃＳ Using the air volume fraction f ｂＳ Next, in the same manner as for sample (B), the complex dielectric constant ε of sample (S) (containing PTFE, air, and dielectric powder) was calculated from the measurement results (Dk and Df) of measurement sample (S). ｄＳ The complex permittivity of air, ε ｂ is assumed to be 1.0, and ε calculated using sample (B) ａ And, fａＳ , f ｂＳ , f ｃＳ , and ε ｄＳ Using the formula (ii), the complex dielectric constant ε of the dielectric powder is calculated. ｃ The calculated ε ｃ From this, Dk and Df of the dielectric powder were calculated.

[0364] (2) Average Particle Diameter The average particle diameters (D50, μm) of the dielectric powders (strontium titanate, spherical calcium titanate, surface-coated titanium oxide, and barium titanate) and the inorganic fillers (calcined talc, fused spherical silica, spherical alumina, fine talc, and boehmite) were calculated by measuring the particle size distribution by a laser diffraction / scattering method using a laser diffraction / scattering particle size distribution analyzer (Microtrac (registered trademark) MT3300EXII (product name), Microtrac-Bell Co., Ltd.) under the following measurement conditions. (Measurement conditions for the laser diffraction / scattering particle size distribution analyzer) - Strontium titanate... Solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 2.41, transmittance: 85±5%. - Spherical calcium titanate... Solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 2.41, transmittance: 85±5%. Surface-coated titanium oxide...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 2.72, transmittance: 85±5%. Barium titanate...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 2.41, transmittance: 85±5%. Calcined talc...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 1.54, transmittance: 85±5%. Fused spherical silica...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 1.45, transmittance: 85±5%. Spherical alumina...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 1.77, transmittance: 85±5%. Finely divided talc...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 1.54, transmittance: 85±5%. Boehmite...solvent: methyl ethyl ketone, solvent refractive index: 1.33, particle refractive index: 1.65, transmittance: 85±5%.

[0365] (3) Absorbance at a wavelength of 9.3 μm The absorbance at a wavelength of 9.3 μm (wave number: 1075 cm) of the dielectric powders (strontium titanate, spherical calcium titanate, surface-coated titanium oxide, and barium titanate) and the inorganic fillers (calcined talc, fused spherical silica, spherical alumina, fine powder talc, and boehmite) was －１ The absorbance at 1000 kJ / cm 2 was measured using the KBr tablet method of Fourier transform infrared spectroscopy as follows. That is, 100 mg of potassium bromide (KBr) powder was weighed per 1 mg of dielectric powder or inorganic filler, and they were crushed in a mortar to obtain a mixed powder. The mixed powder was press-molded using a hand press and an attached tablet molding machine (Mini Hand Press MHP-1 (trade name) manufactured by Shimadzu Corporation) to obtain a film-like measurement sample. A Fourier transform infrared spectrophotometer (IRSpirit (registered trademark), manufactured by Shimadzu Corporation) was used to perform background measurement without using a sample. Thereafter, the obtained measurement sample was loaded into the spectrophotometer, and a 500 cm －１ More than 4000cm －１ The infrared absorption spectrum was obtained as follows. The absorbance at a wavelength of 9.3 μm was obtained using the infrared absorption spectrum. The absorbance was calculated by dividing the incident light intensity in the background measurement by I ０ , where I is the reflected light intensity, log(I ０ In the obtained infrared absorption spectrum, the value at 700 cm －１ More than 1500cm －１ FIG. 1 shows the infrared absorption spectra of the dielectric powders (strontium titanate and surface-coated titanium oxide) and inorganic fillers (calcined talc (BST-200L (trade name)) of Example 1, fused spherical silica, spherical alumina, finely powdered talc, and boehmite) described below.

[0366] (4) Melting Point The melting points (°C) of the dielectric powders (strontium titanate, spherical calcium titanate, surface-coated titanium oxide, and barium titanate) and the inorganic fillers (calcined talc, fused spherical silica, spherical alumina, fine talc, and boehmite) were measured using a simultaneous differential thermal and thermogravimetric analyzer as follows: That is, the melting points of the dielectric powders or inorganic fillers were measured by increasing the temperature from 1000°C to 2000°C at a rate of 10°C / min under an argon gas flow using a simultaneous differential thermal and thermogravimetric analyzer (THEMYS (registered trademark), manufactured by SETARAM Instrumentation).

[0367] (5) X-ray Diffraction The crystal structures of the calcined talc and finely powdered talc in the inorganic filler were each identified using X-ray diffraction (XRD) as follows. That is, calcined talc or finely powdered talc was applied to a standard glass sample plate, and an X-ray diffraction pattern was obtained under the following measurement conditions. The obtained diffraction pattern was analyzed using integrated powder X-ray analysis software (PDXL2 (trade name) manufactured by Rigaku Corporation). Information on the peak positions and peak intensities of the diffraction pattern was collated with information from a database (ICDD, International Centre for Diffraction Data) to identify the crystalline phase, thereby identifying the calcined talc and finely powdered talc.

[0368] (Measurement conditions) X-ray diffraction apparatus: MiniFlex (registered trademark) 600 (product name) manufactured by Rigaku Corporation, θ / 2θ scan, tube voltage: 40 kV, tube current: 15 mA, X-ray source: CuKα (λ=1.54056 Å), slit: DS, 0.5°, solar slit: 2.5 deg.

[0369] [Synthesis Method] The 1-naphthol aralkyl cyanate ester compound (SN495V-CN) was synthesized as follows: 300 g (1.28 mol in terms of OH groups) of 1-naphthol aralkyl phenolic resin (SN495V (trade name), OH group (hydroxy group) equivalent: 236 g / eq., Nippon Steel Chemical Co., Ltd.) and 194.6 g (1.92 mol) of triethylamine (1.5 mol per mol of hydroxy groups) were dissolved in 1,800 g of dichloromethane, and the resulting solution was designated as Solution 1. 125.9 g (2.05 mol) of cyanogen chloride (1.6 mol relative to 1 mol of hydroxy groups), 293.8 g of dichloromethane, 194.5 g (1.92 mol) of 36% hydrochloric acid (1.5 mol relative to 1 mol of hydroxy groups), and 1,205.9 g of water were stirred, and while maintaining the liquid temperature at -2°C or higher and -0.5°C or lower, Solution 1 was added over 30 minutes. After the addition of Solution 1 was completed, the mixture was stirred at the same temperature for 30 minutes, and then a solution (Solution 2) prepared by dissolving 65 g (0.64 mol) of triethylamine (0.5 mol relative to 1 mol of hydroxy groups) in 65 g of dichloromethane was added over 10 minutes. After the addition of Solution 2 was completed, the mixture was stirred at the same temperature for 30 minutes to complete the reaction. The reaction solution was then allowed to stand, and the organic and aqueous phases were separated. The resulting organic phase was washed five times with 1,300 g of water. The electrical conductivity of the wastewater after the fifth water wash was 5 μS / cm, confirming that the ionic compounds that can be removed by washing with water were sufficiently removed. The organic phase after water washing was concentrated under reduced pressure and finally concentrated to dryness at 90° C. for 1 hour to obtain the target 1-naphthol aralkyl cyanate ester compound (SN495V-CN, cyanate ester group equivalent: 261 g / eq., R in the above formula (7) ６ All of n are hydrogen atoms, and n5 is an integer from 1 to 10) (orange viscous substance) was obtained in an amount of 331 g. The infrared absorption spectrum of the obtained SN495V-CN was -1 The absorption of the cyanate ester group was observed, and the absorption of the hydroxyl group was not observed.

[0370] Example 1 A thermosetting resin (C) was prepared using 25 parts by mass of the 1-naphthol aralkyl cyanate ester compound (SN495V-CN) obtained in Synthesis Example 1, 25 parts by mass of a biphenyl aralkyl epoxy resin (NC-3000FH (trade name), epoxy equivalent: 328 g / eq., manufactured by Nippon Kayaku Co., Ltd.) as the thermosetting resin (C), 50 parts by mass of a biphenyl aralkyl maleimide compound (MIR-3000-70MT (trade name), Nippon Kayaku Co., Ltd.) as the thermosetting resin (C), and strontium titanate (SrTiO ３ and 300 parts by mass of ST-03 (product name, manufactured by Sakai Chemical Industry Co., Ltd.), an oxide having a perovskite structure, having an average particle size (D50): 0.30 μm, a relative dielectric constant (Dk): 21, a dielectric loss tangent (Df): 0.007, an absorbance at a wavelength of 9.3 μm: 0.00, a melting point: 2000°C or higher (reference value: 2080°C, a value described in Thermoelectrics based on strontium titanate, Ohta, materials today, October 2007, Vol. 10 (number 10), pp. 44-49 (reference name)), and an inorganic filler (B) containing calcined talc (Mg ２ Si ２ O ６ An alkaline earth metal silicate having the structure (average particle size (D50): 4.00 μm, relative dielectric constant (Dk): 5.8, dielectric dissipation factor (Df): 0.003, absorbance at a wavelength of 9.3 μm: 0.78, melting point: 1550°C, BST-200L (trade name), manufactured by Nippon Talc Co., Ltd.) 50 parts by mass, a wetting dispersant (BYK (registered trademark)-W903 (trade name), manufactured by BYK Japan Co., Ltd.) 3 parts by mass, 2,4,5-triphenylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.1 parts by mass, manganese octylate (Nikka Octyx Manganese (trade name), manufactured by Nippon Chemical Industry Co., Ltd.) 0.5 parts by mass, and 100 parts by mass of methyl ethyl ketone were mixed to obtain a resin varnish. Note that the above blending parts excluding the solvent are values ​​based on the solid content. The same applies to other examples and comparative examples.

[0371] The X-ray diffraction pattern of the calcined talc (BST-200L (trade name)) is shown in FIG. 2. In FIG. 2, the peaks (diffraction lines) at 2θ of 20, 28, 30, and 31 degrees indicate that the calcined talc contains Mg. ２ Si ２ O ６ It was confirmed that the compound was an alkaline earth metal silicate having the structure:

[0372] The obtained resin varnish was applied by impregnation to a 0.032 mm thick E-glass cloth (570 S101S (trade name), manufactured by Nitto Denko Corporation) and dried by heating at 130°C for 3 minutes, thereby obtaining a prepreg with a thickness of 0.060 mm. The obtained resin varnish was also applied by impregnation to a 0.094 mm thick E-glass cloth (1031NT S640 (trade name), manufactured by Arisawa Manufacturing Co., Ltd.) and dried by heating at 130°C for 3 minutes, thereby obtaining a prepreg with a thickness of 0.100 mm. Next, 12 μm thick electrolytic copper foil (3EC-M3-VLP (trade name), manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on the top and bottom surfaces of the obtained 0.100 mm thick prepreg, and a surface pressure of 30 kgf / cm was applied. ２ A metal foil-clad laminate (double-sided copper-clad laminate) having a thickness of 0.124 mm was produced by laminating the prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm under vacuum at a temperature of 220° C. for 120 minutes. The physical properties of the resulting prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm were measured according to the evaluation methods. The results are shown in Table 1.

[0373] Example 2 A resin varnish was obtained in the same manner as in Example 1, except that 100 parts by mass of calcined talc (BST-200L (trade name)) was blended as the inorganic filler (B) instead of 50 parts by mass. Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 1.

[0374] Example 3 A resin varnish was obtained in the same manner as in Example 1, except that 30 parts by mass of calcined talc (BST-200L (trade name)) was blended as the inorganic filler (B) instead of 50 parts by mass. Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 1.

[0375] Comparative Example 1 A resin varnish was obtained in the same manner as in Example 1, except that the resin varnish was prepared without using calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 1.

[0376] Comparative Example 2 A resin varnish was obtained in the same manner as in Example 1, except that 50 parts by mass of fused spherical silica (average particle size (D50): 1.10 μm, relative dielectric constant (Dk): 3.3, dielectric dissipation factor (Df): 0.003, absorbance at a wavelength of 9.3 μm: 0.89, melting point: 1650 ° C., SC4053-SQ (trade name), manufactured by Admatechs Co., Ltd.) was blended as the inorganic filler instead of 50 parts by mass of calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. Using the obtained 0.060 mm thick prepreg and 0.124 mm thick metal foil-clad laminate, each physical property was measured according to the evaluation method, and the results are shown in Table 1.

[0377] Comparative Example 3 A resin varnish was obtained in the same manner as in Example 1, except that 50 parts by mass of spherical alumina (average particle size (D50): 3.50 μm, relative dielectric constant (Dk): 6.5, dielectric dissipation factor (Df): 0.002, absorbance at a wavelength of 9.3 μm: 0.14, melting point: 2000 ° C. or higher, AX3-15 (trade name), manufactured by the Micron Division of Nippon Steel Chemical & Material Co., Ltd.) was blended as the inorganic filler instead of 50 parts by mass of calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. The obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm were used to measure the various physical properties according to the evaluation methods. The results are shown in Table 1.

[0378] Comparative Example 4 A resin varnish was obtained in the same manner as in Example 1, except that 50 parts by mass of finely powdered talc (average particle size (D50): 4.50 μm, relative dielectric constant (Dk): 5.8, dielectric loss tangent (Df): 0.003, absorbance at a wavelength of 9.3 μm: 0.55, melting point: 1550° C., MicroAce (registered trademark) P4 (trade name), manufactured by Nippon Talc Co., Ltd.) was blended as the inorganic filler instead of 50 parts by mass of calcined talc (BST-200L (trade name)) as the inorganic filler (B).

[0379] The X-ray diffraction pattern of the fine powder talc (MicroAce (registered trademark) P4 (trade name)) is shown in FIG. 3. In FIG. 3, the peaks (diffraction lines) at 2θ of 10, 19, 28, and 30 degrees indicate that the fine powder talc contains Mg ３ Si ４ O １０ (OH) ２ It was confirmed that the resin varnish was an alkaline earth metal silicate having the structure:

[0043] Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. Using the obtained 0.060 mm thick prepreg and 0.124 mm thick metal foil-clad laminate, each physical property was measured according to the evaluation method, and the results are shown in Table 1.

[0380] Comparative Example 5 A resin varnish was prepared in the same manner as in Example 1, except that 50 parts by mass of boehmite (average particle size (D50): 1.40 μm, relative dielectric constant (Dk): 5.9, dielectric dissipation factor (Df): 0.003, absorbance at a wavelength of 9.3 μm: 0.03, melting point: 2000° C. or higher, BN-100K (product name), manufactured by Kawai Lime Industry Co., Ltd.) was blended as the inorganic filler instead of 50 parts by mass of calcined talc (BST-200L (product name)) as the inorganic filler (B). Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were prepared in the same manner as in Example 1. The physical properties of the resulting prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm were measured according to the evaluation methods, and the results are shown in Table 1.

[0381] Example 4 A resin varnish was obtained in the same manner as in Example 1, except that 300 parts by mass of spherical calcium titanate (CaTiO3, an oxide having a perovskite structure, average particle size (D50): 7.00 μm, relative permittivity (Dk): 19, dielectric dissipation factor (Df): 0.005, absorbance at a wavelength of 9.3 μm: 0.00, melting point: 1380° C., spherical calcium titanate (trade name), manufactured by Denka Co., Ltd.) was blended as the dielectric powder (A) instead of 300 parts by mass of strontium titanate (ST-03 (trade name)) as the dielectric powder (A). Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. The obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm were used to measure the physical properties according to the evaluation methods. The results are shown in Table 2.

[0382] Example 5 A resin varnish was obtained in the same manner as in Example 1, except that 300 parts by mass of surface-coated titanium oxide (crystal structure: rutile type, titanium dioxide surface-treated with silica, alumina, and dimethyl silicone (total content of silica, alumina, and dimethyl silicone: 3% by mass), titanium oxide content: 97% by mass, average particle size (D50): 0.21 μm, relative permittivity (Dk): 24, dielectric dissipation factor (Df): 0.010, absorbance at a wavelength of 9.3 μm: 0.00, melting point: 1720° C., CR-63 (trade name), Ishihara Sangyo Kaisha, Ltd.) was blended as the dielectric powder (A) instead of 300 parts by mass of strontium titanate (ST-03 (trade name)) as the dielectric powder (A). Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. The obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm were used to measure the various physical properties according to the evaluation methods. The results are shown in Table 2.

[0383] Example 6 Instead of 300 parts by mass of strontium titanate (ST-03 (trade name)) as the dielectric powder (A), barium titanate (BaTi ４ O ９ A resin varnish was obtained in the same manner as in Example 1, except that 300 parts by mass of a compound having a structure represented by the formula (I), average particle size (D50): 2.10 μm, relative dielectric constant (Dk): 19, dielectric dissipation factor (Df): 0.003, absorbance at a wavelength of 9.3 μm: 0.00, melting point: 1380 ° C., BT-149 (trade name), manufactured by Nippon Chemical Industry Co., Ltd.) was blended. Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and a metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 2.

[0384] Example 7 Instead of 50 parts by mass of calcined talc (BST-200L (trade name)) as the inorganic filler (B), calcined talc (Mg ２ Si２ O ６ A resin varnish was obtained in the same manner as in Example 1, except that 50 parts by mass of ST-100 (trade name, manufactured by Fuji Talc Kogyo Co., Ltd.) was added.

[0385] When the calcined talc (ST-100 (trade name)) was identified using XRD, peaks (diffraction lines) at 2θ of 20, 28, 30, and 31° were observed in the X-ray diffraction pattern. From these peaks, it was found that the calcined talc contained Mg ２ Si ２ O ６ It was confirmed that the compound was an alkaline earth metal silicate having the structure:

[0386] Using this resin varnish, a 0.060 mm thick prepreg, a 0.100 mm thick prepreg, and a 0.124 mm thick metal foil-clad laminate were obtained in the same manner as in Example 1. Using the obtained 0.060 mm thick prepreg and 0.124 mm thick metal foil-clad laminate, each physical property was measured according to the evaluation method, and the results are shown in Table 2.

[0387] Comparative Example 6 A resin varnish was obtained in the same manner as in Example 4, except that the varnish was prepared without using calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 2.

[0388] Comparative Example 7 A resin varnish was obtained in the same manner as in Example 5, except that the varnish was prepared without using calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 2.

[0389] Comparative Example 8 A resin varnish was obtained in the same manner as in Example 6, except that the varnish was prepared without using calcined talc (BST-200L (trade name)) as the inorganic filler (B). Using this resin varnish, a prepreg having a thickness of 0.060 mm, a prepreg having a thickness of 0.100 mm, and a metal foil-clad laminate having a thickness of 0.124 mm were obtained in the same manner as in Example 1. Using the obtained prepreg having a thickness of 0.060 mm and the metal foil-clad laminate having a thickness of 0.124 mm, each physical property was measured according to the evaluation method, and the results are shown in Table 2.

[0390] [Evaluation method]

[0391] (1) [Laser Processability] Laser processability was evaluated as follows. Using the 0.060 mm thick prepreg and 0.124 mm thick metal foil-clad laminate obtained in each of the Examples and Comparative Examples, evaluation samples were prepared as follows. One 0.060 mm thick prepreg was laminated on top and bottom of a 0.124 mm thick metal foil-clad laminate (double-sided copper-clad laminate). Furthermore, ultra-thin copper foil with carrier foil (MicroThin (registered trademark) 18FL (product name), manufactured by Mitsui Mining & Smelting Co., Ltd., carrier foil thickness: 18 μm, ultra-thin copper foil thickness: 1.5 μm) was placed on the top and bottom surfaces of the laminate, and a surface pressure of 30 kgf / cm was applied. ２The laminate was then vacuum-pressed at 220°C for 120 minutes to produce a 0.283 mm thick metal foil-clad laminate A (double-sided copper-clad laminate A). The carrier foil was removed from the resulting metal foil-clad laminate A, and via holes for interlayer connection were formed in the metal foil-clad laminate to produce a metal foil-clad laminate B. The via holes were drilled using a substrate drilling laser processing machine (ML605GTWIII-H (trade name), carbon dioxide laser, two-work, two-beam specification, manufactured by Mitsubishi Electric Corporation) under the following conditions: a top diameter of the via hole of 80 μm, a laser wavelength of 9.3 μm, a pulse width of 15 μsec, one shot, and a total energy of 6.5 mJ.

[0392] Next, a desmear treatment was performed on the metal foil-clad laminate B. First, a swelling solution (an aqueous solution containing a desmear swelling agent AppDes (registered trademark) MDS-37 (trade name, manufactured by Uemura Kogyo Co., Ltd.)) was heated to 80°C, and the metal foil-clad laminate B was immersed in this aqueous solution for 5 minutes to swell. Next, a roughening solution (an aqueous solution containing a desmear resin roughening agent MDE-40 (trade name, manufactured by Uemura Kogyo Co., Ltd.) and AppDes (registered trademark) ELC-SH (trade name, manufactured by Uemura Kogyo Co., Ltd.)) was heated to 80°C, and the swollen metal foil-clad laminate B was immersed in this aqueous solution for 10 minutes to roughen the surface and dissolve the smear. Subsequently, the metal foil-clad laminate B after surface roughening and smear dissolution was immersed in a neutralizing solution (an aqueous solution containing a desmear neutralizer AppDes (registered trademark) MDN-62 (trade name, manufactured by Uemura Kogyo Co., Ltd.)) at room temperature for 5 minutes to neutralize, thereby obtaining a laminate A for wiring boards.

[0393] Next, the wiring board laminate A was subjected to electroless plating. First, as a pretreatment for electroless plating, a cleaner conditioner (aqueous solution containing cleaner MCD-PL (trade name, Uemura Kogyo Co., Ltd.)) was heated to 40°C, and the wiring board laminate A was immersed in this aqueous solution for 5 minutes. Thereafter, it was rinsed with water to obtain a wiring board laminate B. Next, the wiring board laminate B was immersed for 2 minutes at room temperature in a pre-dip solution (aqueous solution containing alkaline palladium ion catalyst pre-dip, ALCUP (registered trademark) MDP-2 (trade name, Uemura Kogyo Co., Ltd.)) to obtain a wiring board laminate C. Next, the wiring board laminate C was immersed for 5 minutes at room temperature in an electroless plating catalyst solution (aqueous solution containing alkaline palladium ion catalyst activator, ALCUP (registered trademark) MAT-SP (trade name, Uemura Kogyo Co., Ltd.)). Thereafter, it was rinsed with water to obtain a wiring board laminate D. Next, an electroless copper plating solution (aqueous solution containing Thrucup (registered trademark) PEA-6-A (trade name, Uemura Kogyo Co., Ltd.), Thrucup (registered trademark) PEA-6-B (trade name, Uemura Kogyo Co., Ltd.), Thrucup (registered trademark) PEA-6-C (trade name, Uemura Kogyo Co., Ltd.), Thrucup (registered trademark) PEA-6-D (trade name, Uemura Kogyo Co., Ltd.), and Thrucup (registered trademark) PEA-6-E (trade name, Uemura Kogyo Co., Ltd.)) was prepared by immersing the wiring board laminate D at room temperature for 15 minutes to perform an electroless plating process, thereby obtaining a wiring board laminate E. Furthermore, copper sulfate electroplating was performed on the wiring board laminate E using a copper sulfate solution, thereby obtaining a wiring board laminate F.

[0394] Thereafter, the wiring board laminate F was dried at 170°C for 30 minutes to obtain a wiring board laminate G in which a 20 μm thick conductor layer (copper layer) was formed on the surface of the insulating layer.

[0395] The top and bottom surfaces of the obtained wiring board laminate G were sandwiched between 5 cm thick acrylic plates to obtain a wiring board laminate H. Next, using a bench polisher (ECOMET6 (trade name) manufactured by BUEHLER), a sample was cut out along the via hole in the wiring board laminate H so that the cross section of the via hole could be observed, thereby obtaining an evaluation sample. The cross section (lateral surface) of the via hole in the evaluation sample was observed using an inverted microscope (EPIPHOT200 (trade name) manufactured by Nikon Solutions Corporation) and evaluated according to the following criteria. (Evaluation Criteria) A: In the cross section of the via hole, no gouging was observed on the hole wall surface along the fibers of the glass cloth, or if gouging was observed, the length of the gouging was 2 μm or less. B: In the cross section of the via hole, gouging occurred on the hole wall surface along the fibers of the glass cloth, and the length of the gouging was more than 2 μm and 4 μm or less. C: In the cross section of the via hole, gouges were generated on the wall surface of the hole along the fibers of the glass cloth, and the length of the gouges was more than 4 μm and 6 μm or less. D: In the cross section of the via hole, gouges were generated on the wall surface of the hole along the fibers of the glass cloth, and the length of the gouges was more than 6 μm.

[0396] (2) Copper foil peel strength Five sheets of the prepreg having a thickness of 0.060 mm obtained in the examples and comparative examples were laminated, and electrolytic copper foil having a thickness of 12 μm (3EC-M3-VLP (trade name), manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on the top and bottom surfaces of the laminate. A surface pressure of 30 kgf / cm was applied. ２ A metal foil-clad laminate (double-sided copper-clad laminate) having a thickness of 0.324 mm was produced by laminating the laminated sheet at a temperature of 220° C. for 120 minutes. The copper foil peel strength (copper foil adhesion, kN / m) of this metal foil-clad laminate (10 mm × 100 mm × 0.324 mm) was measured in accordance with JIS C6481.

[0397] (3) Evaluation of moisture absorption and heat resistance (thermal properties) Five sheets of the prepreg having a thickness of 0.060 mm obtained in the examples and comparative examples were laminated, and electrolytic copper foil having a thickness of 12 μm (3EC-M3-VLP (product name), manufactured by Mitsui Mining & Smelting Co., Ltd.) was placed on the top and bottom surfaces of the laminate. ２A 0.324 mm thick metal foil-clad laminate (double-sided copper-clad laminate) was produced by laminating and vacuum pressing at a temperature of 220°C for 120 minutes. This metal foil-clad laminate was cut (downsized) to a size of 50 mm x 50 mm x 0.324 mm. Then, all of the copper foil on one side was removed by etching, and half of the copper foil surface on the other side was removed by etching to produce a measurement sample. Four measurement samples were prepared in the same manner as above. Each measurement sample was treated for 3 hours in the presence of saturated steam at 121°C and 2 atmospheres using a pressure cooker tester (PC-3 model (trade name), Hirayama Manufacturing Co., Ltd.). The sample was then immersed (dipped) in a solder bath at 260°C for 60 seconds, and the presence or absence of abnormalities in appearance was visually observed and evaluated according to the following criteria. (Evaluation Criteria) A: No abnormalities in appearance were observed in all four measurement samples. C: Out of the four measurement samples, one or more samples were found to have abnormal appearance.

[0398] (4) Relative permittivity (Dk) and dielectric loss tangent (Df) Five prepregs each having a thickness of 0.060 mm obtained in the examples and comparative examples were laminated together, and electrolytic copper foils having a thickness of 12 μm (3EC-M3-VLP (product name), manufactured by Mitsui Mining & Smelting Co., Ltd.) were placed on the top and bottom surfaces of the laminated prepregs. A surface pressure of 30 kgf / cm was applied to the laminated prepregs. ２ A 0.324 mm thick metal foil-clad laminate (double-sided copper-clad laminate) was produced by laminating and vacuum pressing at a temperature of 220 ° C for 120 minutes. The copper foil on both sides of this metal foil-clad laminate was completely etched to obtain a 0.300 mm thick unclad plate from which all copper foil on both sides had been removed. This unclad plate was cut (downsized) to a size of 1 mm x 65 mm x 0.300 mm to obtain a measurement sample. Using this measurement sample, the relative dielectric constant (Dk) and dielectric loss tangent (Df) at a frequency of 10 GHz were measured using a network analyzer (Agilent (registered trademark) 8722ES (trade name), manufactured by Agilent Technologies, Inc.). The measurements of the relative dielectric constant (Dk) and dielectric loss tangent (Df) were performed in an environment of a temperature of 23 ° C ± 1 ° C and a humidity of 50% RH ± 5% RH.

[0399]

[0400]

[0401] The resin composition of the present invention has a high dielectric constant and a low dielectric loss tangent when cured, and exhibits excellent thermal properties such as moisture absorption and heat resistance, excellent laser processability, and high metal foil peel strength. Therefore, the resin composition of the present invention can be suitably used as a raw material for, for example, cured products, prepregs, film-like underfill materials, resin sheets, laminates, build-up materials, non-conductive films, metal foil-clad laminates, printed wiring boards, and fiber-reinforced composite materials, or in the manufacture of semiconductor devices. The resin composition of the present invention is particularly suitable for use in the manufacture of insulating layers for printed wiring boards.

[0402] This application is based on a Japanese patent application (Patent Application No. 2023-219669) filed on December 26, 2023, the contents of which are incorporated herein by reference.

Claims

1. A resin composition comprising a dielectric powder (A) having a relative permittivity of 12.0 or more at a frequency of 10 GHz measured according to the cavity resonator perturbation method, an inorganic filler (B) which is different from the dielectric powder (A) and has an absorbance of 0.70 or more at a wavelength of 9.3 μm, a melting point of 1600 ° C. or less, in an infrared absorption spectrum obtained using Fourier transform infrared spectroscopy, and a thermosetting resin (C).

2. The resin composition according to claim 1, wherein the mass ratio ((A):(B)) of the dielectric powder (A) to the inorganic filler (B) is 300:10 to 300:

150.

3. The resin composition according to claim 1, wherein the dielectric tangent of the dielectric powder (A) at a frequency of 10 GHz measured according to the cavity resonator perturbation method is 0.015 or less.

4. The resin composition according to claim 1, wherein the dielectric powder (A) contains a titanium-based inorganic filler.

5. The resin composition according to claim 4, wherein the titanium-based inorganic filler contains at least one selected from the group consisting of an uncoated titanium-based inorganic filler and a surface-coated titanium-based inorganic filler.

6. The resin composition according to claim 5, wherein the uncoated titanium-based inorganic filler contains at least one selected from the group consisting of titanium monoxide, titanium dioxide, dititanium trioxide, potassium titanate, calcium titanate, strontium titanate, barium titanate, aluminum titanate, and lead titanate.

7. The resin composition according to claim 5, wherein the surface-coated titanium-based inorganic filler contains surface-coated titanium oxide.

8. The resin composition according to claim 7, wherein the surface-coated titanium oxide has an organic layer and / or an inorganic oxide layer on the surface of titanium oxide particles.

9. The resin composition according to claim 1, wherein the inorganic filler (B) contains an alkaline earth metal silicate.

10. The alkaline earth metal silicate is Mg ２ Si ２ O ６ The resin composition according to claim 9, comprising an alkaline earth metal silicate having a structure of 11. The resin composition according to claim 9, wherein the alkaline earth metal silicate contains calcined talc.

12. The resin composition according to claim 1, wherein the average particle diameter (D50) of the dielectric powder (A) is 0.10 μm or more and 10.00 μm or less, and the average particle diameter (D50) of the inorganic filler (B) is 0.10 μm or more and 10.00 μm or less.

13. The resin composition according to claim 1, wherein the content of the dielectric powder (A) is 50 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass in total of the resin solids in the resin composition.

14. The resin composition according to claim 1, wherein the content of the inorganic filler (B) is 10 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass in total of the resin solids in the resin composition.

15. The resin composition according to claim 1, wherein the thermosetting resin (C) contains one or more selected from the group consisting of a maleimide compound, a cyanate ester compound, an epoxy compound, a phenol compound, a modified polyphenylene ether compound, an alkenyl-substituted nadimide compound, an oxetane resin, a benzoxazine compound, and a compound having a polymerizable unsaturated group.

16. The resin composition according to claim 15, wherein the maleimide compound contains one or more selected from the group consisting of bis(4-maleimidophenyl)methane, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, a maleimide compound represented by the following formula (1), a maleimide compound represented by the following formula (2), a maleimide compound represented by the following formula (3), and a maleimide compound represented by the following formula (4). (In formula (1), R １ each independently represents a hydrogen atom or a methyl group, and n1 is an integer of 1 to 10.). (In formula (2), R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group, and n2 is an average value, indicating 1 < n2 ≤ 5.). (In formula (3), Ra each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, or an alkylthio group, an aryl group having 6 to 10 carbon atoms, an aryloxy group, or an arylthio group, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a nitro group, a hydroxy group, or a mercapto group. q represents an integer of 0 to 4. When q is an integer of 2 to 4, Ra may be the same or different within the same ring. Rb each independently represents an alkyl group having 1 to 10 carbon atoms, an alkyloxy group, or an alkylthio group, an aryl group having 6 to 10 carbon atoms, an aryloxy group, or an arylthio group, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. r represents an integer of 0 to 3. When r is 2 or 3, Rb may be the same or different within the same ring. n3 is an average value, indicating a value of 0.95 to 10.0.). (In formula (4), R １ each independently represents an alkyl group having 1 to 10 carbon atoms. s represents an integer of 1 to 3. R ２ each independently represents an alkyl group, an alkyloxy group, or an alkylthio group having 1 to 10 carbon atoms, an aryl group, an aryloxy group, or an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. t represents an integer of 0 to 4. R ３ each independently represents a group represented by the following formula (5). u represents an integer of 0 to 2. R ４ represents a hydrogen atom or a group represented by the following formula (5). R ５ represents a hydrogen atom or a group represented by the following formula (6). n4 represents an integer of 1 to 100.) (In formula (5), R ６ each independently represents an alkyl group, an alkyloxy group, or an alkylthio group having 1 to 10 carbon atoms, an aryl group, an aryloxy group, or an arylthio group having 6 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a halogen atom, a hydroxy group, or a mercapto group. v represents an integer of 0 to 4. *1 indicates the bonding site with a carbon atom.) (In formula (6), R ７ each independently represents an alkyl group having 1 to 10 carbon atoms. w represents an integer of 1 to 3. R ８ each independently represents the group represented by the above formula (5). x represents an integer of 0 to 2. *2 indicates the bonding site with a carbon atom.).

17. The resin composition according to claim 15, wherein the cyanate ester compound contains one or more selected from the group consisting of a phenol novolac type cyanate ester compound, a naphthol aralkyl type cyanate ester compound, a naphthylene ether type cyanate ester compound, a xylene resin type cyanate ester compound, a bisphenol M type cyanate ester compound, a bisphenol A type cyanate ester compound, a diallylbisphenol A type cyanate ester compound, a bisphenol E type cyanate ester compound, a bisphenol F type cyanate ester compound, and a biphenyl aralkyl type cyanate ester compound, and prepolymers or polymers of these cyanate ester compounds.

18. The resin composition according to claim 15, wherein the epoxy compound contains one or more selected from the group consisting of a biphenyl aralkyl type epoxy resin, a naphthalene type epoxy resin, a naphthylene ether type epoxy resin, and a butadiene skeleton-containing epoxy resin.

19. The resin composition according to claim 1, which is for a printed wiring board.

20. A cured product containing the resin composition according to any one of claims 1 to 19.

21. A prepreg comprising a base material and the resin composition according to any one of claims 1 to 19 impregnated or coated on the base material.

22. A resin sheet containing the resin composition according to any one of claims 1 to 19.

23. A laminated board containing the prepreg according to claim 21.

24. A laminated board containing the resin sheet according to claim 22.

25. A metal foil-clad laminated board comprising the laminated board according to claim 23 and a metal foil disposed on one or both sides of the laminated board.

26. A metal foil-clad laminated board comprising the laminated board according to claim 24 and a metal foil disposed on one or both sides of the laminated board.

27. A printed wiring board having an insulating layer and a conductor layer disposed on one or both sides of the insulating layer, wherein the insulating layer contains a cured product of the resin composition according to any one of claims 1 to 19.