Printed wiring board and its manufacturing method

Abstract

To provide a manufacturing method for a printed wiring board that enables efficient formation of recesses by plasma treatment.SOLUTION: A method for manufacturing a printed wiring board has a step for forming an insulating layer on an inner layer substrate and a step for forming recesses in the insulating layer by plasma treatment, and the insulating layer includes a cured product of a resin composition containing an inorganic filler, and an inorganic filler includes an inorganic filler having a porosity of 10% or more by volume.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printed wiring board and a method for manufacturing the same. [Background technology]

[0002] A known manufacturing technique for printed wiring boards is a build-up method in which insulating layers and conductor layers are alternately stacked. In build-up manufacturing methods, the insulating layer is generally formed from a cured product obtained by curing a resin composition (Patent Documents 1 to 3). In order to reduce the coefficient of linear thermal expansion (CTE) of the insulating layer and thereby suppress warping of the printed wiring board, a resin composition containing an inorganic filler is often used to form the insulating layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-60800 [Patent Document 2] Japanese Patent Publication No. 2022-66981 [Patent Document 3] Japanese Patent Publication No. 2022-039763 Summary of the Invention [Problem to be solved by the invention]

[0004] Insulation layers of printed wiring boards are sometimes formed with recesses such as trenches and via holes. Conventionally, a common method for forming a conductor layer on an insulation layer involves forming recesses by laser processing using a carbon dioxide laser, performing a wet desmearing process to remove smears using an oxidizing solution, and then performing wet electroless plating. Here, "smear" refers to resin residue formed by laser processing.

[0005] However, the wet process generates waste liquid, which poses a problem in terms of environmental impact, and therefore, in recent years, there has been a demand for the development of a technology that can replace the wet process with a dry process.

[0006] As one dry process, the inventors have investigated a method for forming recesses in an insulating layer by plasma treatment. Plasma treatment has the advantages of suppressing smear formation in the recesses, reducing the dimensions of the recesses, and reducing the environmental impact by not producing waste liquid. However, plasma treatment has the problem of lower processability compared to laser processing using a carbon dioxide laser.

[0007] The present invention has been devised in view of the above-mentioned problems, and aims to provide a method for manufacturing a printed wiring board that enables efficient formation of recesses by plasma treatment, and a printed wiring board that can be manufactured by the method. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that recesses can be efficiently formed by plasma treatment in an insulating layer formed of a cured product of a resin composition containing an inorganic filler having a specific porosity, thereby completing the present invention. That is, the present invention includes the following.

[0009] [1] forming an insulating layer on an inner layer substrate; a step of subjecting the insulating layer to a plasma treatment to form a recess; the insulating layer includes a cured product of a resin composition including an inorganic filler; A method for producing a printed wiring board, wherein the inorganic filler contains an inorganic filler having a porosity of 10% by volume or more. [2] A method for manufacturing a printed wiring board according to [1], which includes, before the step of forming a recess in the insulating layer, a step of forming a mask layer on the insulating layer to cover the area other than the area where the recess is to be formed. [3] A method for producing a printed wiring board according to [1] or [2], comprising the step of forming a conductor layer on an insulating layer. [4] The method for producing a printed wiring board according to [3], wherein the conductor layer is formed by a sputtering method. [5] The method for producing a printed wiring board according to any one of [1] to [4], wherein the porous inorganic filler has an average particle size of 5 μm or less. [6] The method for producing a printed wiring board according to any one of [1] to [5], wherein the porosity of the porous inorganic filler is 40% by volume or more. [7] The method for producing a printed wiring board according to any one of [1] to [6], wherein the porous inorganic filler contains an inorganic oxide. [8] The cured product of the resin composition has a viscosity of 1.8 g / cm 3 The method for producing a printed wiring board according to any one of [1] to [7], wherein the printed wiring board has the following density: [9] A printed wiring board comprising an inner layer substrate and an insulating layer formed on the inner layer substrate, the insulating layer includes a cured product of a resin composition including an inorganic filler; The inorganic filler includes an inorganic filler having a porosity of 10% by volume or more; A recess is formed in the insulating layer, A printed wiring board, wherein the surface of the recess includes a surface portion formed by scraping away particles of an inorganic filler having porosity. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for manufacturing a printed wiring board that can efficiently form recesses by plasma treatment, and a printed wiring board that can be manufactured by the method. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an inner layer substrate and an insulating layer of an example of a printed wiring board manufactured according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with any modifications within the scope of the claims and their equivalents.

[0013] In the following description, "dielectric constant" refers to "relative dielectric constant" unless otherwise specified.

[0014] In the following description, the term "(meth)acrylic" includes acrylic, methacrylic, and combinations thereof. The term "(meth)acrylate" includes acrylate, methacrylate, and combinations thereof. The term "(meth)acrylonitrile" includes acrylonitrile, methacrylonitrile, and combinations thereof.

[0015] <Outline of printed wiring board manufacturing method> A method for manufacturing a printed wiring board according to one embodiment of the present invention includes the steps of: Step (I) of forming an insulating layer on an inner layer substrate; a step (III) of subjecting the insulating layer to a plasma treatment to form recesses; The insulating layer includes a cured product of a resin composition including an inorganic filler, and the inorganic filler includes an inorganic filler having a porosity within a specific range.

[0016] According to this manufacturing method, when forming recesses by plasma treatment in step (III), the recesses can be formed efficiently. Therefore, recesses such as via holes and trenches can be formed in a short time, thereby improving the manufacturing efficiency of printed wiring boards. Furthermore, in printed wiring boards manufactured by this manufacturing method, the relative dielectric constant of the insulating layer can usually be reduced.

[0017] The method for manufacturing a printed wiring board according to this embodiment may further include any optional step in addition to the steps (I) and (III). For example, the method for manufacturing a printed wiring board may include a step (II) of forming a mask layer on the insulating layer to cover the portion other than the portion where the recess is to be formed, before the step (III) of forming a recess in the insulating layer. Furthermore, for example, the method for manufacturing a printed wiring board may include a step (IV) of removing the mask layer after the step (III) of forming a recess in the insulating layer. Furthermore, for example, the method for manufacturing a printed wiring board may include a step (V) of forming a conductor layer on the insulating layer. The step (V) of forming the conductor layer may be performed before the step (III) of forming the recess, or after the step (III), depending on the method for forming the conductor layer.

[0018] <Inner layer board> The "internal substrate" used in step (I) refers to a component that will become the substrate of a printed wiring board, and examples thereof include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The substrate may have a conductor layer on one or both sides, and this conductor layer may be patterned. The conductor layer of the internal substrate may be referred to as the "substrate conductor layer" below. For example, a circuit board may have a support substrate and a substrate conductor layer provided on the surface of the support substrate. In this case, the substrate conductor layer of the internal substrate is usually exposed on the main surface of the internal substrate. An internal substrate having a substrate conductor layer (circuit) formed on one or both sides of the substrate may be referred to as an "internal circuit board." Furthermore, an intermediate product on which an insulating layer and / or a conductor layer is to be further formed during the production of a printed wiring board is also included in the "internal substrate." When the printed wiring board is a circuit board with built-in components, an internal substrate with built-in components may be used.

[0019] <Resin composition> In step (I), an insulating layer containing a cured resin composition is formed on an inner layer substrate. Therefore, the insulating layer is usually formed using a resin composition. This resin composition contains (A) an inorganic filler and usually also contains (B) a curable resin.

[0020] -(A) Inorganic filler- The (A) inorganic filler as component (A) is usually contained in the resin composition in the form of particles, and is contained in the cured product while maintaining this particulate form. Inorganic compounds can be used as the material for the (A) inorganic filler. Examples of materials for the (A) inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium titanate zirconate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, inorganic oxides are preferred.

[0021] Inorganic oxides include inorganic complex oxides. An inorganic complex oxide refers to an oxide containing two or more types of atoms selected from the group consisting of metal atoms and metalloid atoms. As such inorganic complex oxides, oxides containing a combination of silicon and one or more types of atoms selected from the group consisting of metal atoms and metalloid atoms other than silicon are preferred. Metal atoms that can be combined with silicon include aluminum, lead, nickel, cobalt, copper, zinc, zirconium, iron, lithium, magnesium, barium, potassium, calcium, titanium, boron, sodium, and the like, with aluminum being particularly preferred. Therefore, as inorganic complex oxides, oxides containing silicon and aluminum are preferred, with aluminosilicates being particularly preferred.

[0022] Among these materials for (A) inorganic filler, inorganic oxides are preferred, silica, alumina and aluminosilicate are more preferred, and silica is particularly preferred. (A) inorganic filler may be used alone or in combination of two or more.

[0023] (A) Inorganic fillers can be classified into inorganic fillers having internal voids and inorganic fillers having no internal voids. Inorganic fillers having internal voids usually have a porosity greater than 0% by volume because they have voids. In the method for producing a printed wiring board according to this embodiment, the (A) inorganic filler includes (A-1) an inorganic filler having a porosity within a specific range. Hereinafter, this (A-1) inorganic filler having a porosity within a specific range may be referred to as the "(A-1) specific inorganic filler."

[0024] The porosity range of the specific inorganic filler (A-1) is usually 10% by volume or more, preferably 15% by volume or more, more preferably 20% by volume or more, even more preferably 30% by volume or more, even more preferably 40% by volume or more, even more preferably 50% by volume or more, and particularly preferably 60% by volume or more. When the inorganic filler (A) contains the specific inorganic filler (A-1) having a porosity within this range, the formation of recesses in the insulating layer by plasma treatment can be carried out efficiently, and more usually, the relative dielectric constant of the insulating layer can be reduced. From the viewpoint of the mechanical strength of the insulating layer, the upper limit of the porosity range of the specific inorganic filler (A-1) is preferably 95% by volume or less, more preferably 90% by volume or less, and particularly preferably 85% by volume or less.

[0025] The porosity P (vol %) of a particle is defined as the volume ratio of the total volume of one or more pores present inside the particle to the total volume of the particle based on the outer surface of the particle (total volume of pores / volume of particle). This porosity P is calculated by the measured value of the actual density D of the particle. M (g / cm 3 ), and the theoretical value of the material density of the material that forms the particle, D T (g / cm 3 ) can be calculated using the following formula (X1).

[0026]

number

[0027] The material of the (A-1) specific inorganic filler may be the same as the material range of the (A) inorganic filler described above. Among these, the material contained in the (A-1) specific inorganic filler is preferably an inorganic oxide, more preferably silica, alumina, or aluminosilicate, and particularly preferably silica.

[0028] The specific inorganic filler (A-1) may be a monoporous particle having only one pore therein, a multiporous particle having two or more pores therein, or a combination of monoporous and multiporous particles.

[0029] Particles of the (A-1) specific inorganic filler generally have voids formed within the particle and an outer shell formed of an inorganic compound surrounding the voids. The voids may be separated from the outside of the particle by the outer shell, or may be open to the outside of the particle without being separated from the outside of the particle by the outer shell. Examples of inorganic fillers in which voids are open to the outside of the particle include porous inorganic fillers. Among these, it is preferable that the (A-1) specific inorganic filler has voids that are not open to the outside. Hereinafter, inorganic fillers having voids that are not open to the outside of the particle may be referred to as "hollow inorganic fillers." The outer shell of such hollow inorganic fillers is usually a non-porous shell that does not have pores connecting the voids to the outside of the particle. The non-porous nature of the outer shell can be confirmed by observation with a transmission electron microscope (TEM).

[0030] The average particle size of the (A-1) specific inorganic filler is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. When the average particle size of the (A-1) specific inorganic filler is within this range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced. Furthermore, from the viewpoint of forming the opening shape of the recesses formed in the insulating layer with the intended precision, the average particle size of the (A-1) specific inorganic filler is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less. The lower limit of the range of the average particle size of the (A-1) specific inorganic filler can be, for example, 0.01 μm or more, 0.1 μm or more, or 0.3 μm or more.

[0031] The average particle size can be measured using a laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution based on volume is created using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size. A measurement sample of inorganic filler can be prepared by weighing 100 mg of inorganic filler and 10 g of methyl ethyl ketone into a vial and dispersing the mixture ultrasonically for 10 minutes. The measurement sample is measured using a laser diffraction particle size distribution analyzer with blue and red light source wavelengths using a flow cell system to measure the volumetric particle size distribution of the inorganic filler, and the average particle size can be calculated as the median diameter from the particle size distribution obtained. Examples of laser diffraction particle size distribution analyzers include the LA-960 manufactured by Horiba, Ltd.

[0032] (A-1) The range of the BET specific surface area of ​​the specific inorganic filler is preferably 1 m 2 / g or more, more preferably 2m 2 / g or more, particularly preferably 5m 2 / g or more, preferably 100m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 30m 2 / g or less. (A-1) When the BET specific surface area of ​​the specific inorganic filler is within the above range, recesses can be efficiently formed in the insulating layer by plasma treatment, and moreover, the relative dielectric constant of the insulating layer can usually be reduced. The BET specific surface area of ​​the particles can be measured according to the BET method by adsorbing nitrogen gas onto the sample surface using a specific surface area measuring device (Macsorb HM-1210 manufactured by Mountech Co., Ltd.) and calculating the specific surface area using the BET multipoint method.

[0033] The specific inorganic filler (A-1) may be a commercially available product or may be produced by a conventional method. The specific inorganic filler (A-1) may be used alone or in combination of two or more types.

[0034] The (A-1) specific inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of the surface treatment agent include a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an alkoxysilane, an organosilazane compound, and a titanate coupling agent. One type of surface treatment agent may be used alone, or two or more types may be used in any combination.

[0035] Examples of commercially available surface treatment agents include Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical Co., Ltd.'s "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

[0036] From the viewpoint of improving dispersibility, the degree of surface treatment with the surface treatment agent preferably falls within a specific range. Specifically, 100% by mass of the specific inorganic filler (A-1) is preferably surface-treated with 0.2% to 20% by mass of the surface treatment agent, more preferably with 0.2% to 16% by mass of the surface treatment agent, and even more preferably with 0.3% to 12% by mass of the surface treatment agent.

[0037] The degree of surface treatment with the surface treatment agent can be evaluated by the amount of carbon per unit surface area of ​​the (A-1) specific inorganic filler. From the viewpoint of improving the dispersibility of the (A-1) specific inorganic filler, the range of the amount of carbon per unit surface area of ​​the (A-1) specific inorganic filler is 0.02 mg / m 2More than 0.1 mg / m is preferable. 2 More preferably, 0.2 mg / m or more 2 On the other hand, from the viewpoint of preventing an increase in the melt viscosity of the resin composition, it is more preferable that the content be 1.0 mg / m 2 Less than 0.8 mg / m is preferred 2 Less than 0.5 mg / m is more preferable. 2 The following is even more preferred:

[0038] The carbon amount per unit surface area of ​​the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solid content, the carbon amount per unit surface area of ​​the inorganic filler can be measured using a carbon analyzer. The carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

[0039] The range of the amount (mass %) of the specific inorganic filler (A-1), when the nonvolatile components in the resin composition are taken as 100 mass %, is preferably 1 mass % or more, more preferably 3 mass % or more, even more preferably 5 mass % or more, even more preferably 6 mass % or more, and particularly preferably 10 mass % or more, and is preferably 90 mass % or less, more preferably 85 mass % or less, and even more preferably 80 mass % or less. When the amount of the specific inorganic filler (A-1) is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0040] The range of the amount (vol %) of the specific inorganic filler (A-1), when the nonvolatile components in the resin composition are taken as 100 vol %, is preferably 1 vol % or more, more preferably 3 vol % or more, even more preferably 5 vol % or more, even more preferably 7 vol % or more, and particularly preferably 10 vol % or more, and is preferably 90 vol % or less, more preferably 80 vol % or less, and even more preferably 70 vol % or less. When the amount of the specific inorganic filler (A-1) is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0041] The range of the volume-based amount (vol %) of each component contained in the resin composition can be calculated from the mass of the component contained in the resin composition. Specifically, the volume of each component can be calculated by dividing the mass by the specific gravity, and the volume-based amount (vol %) can be calculated from the volume of each component thus calculated.

[0042] The amount (% by mass) of the (A-1) specific inorganic filler is preferably 1% by mass to 100% by mass, more preferably 3% by mass to 100% by mass, even more preferably 5% by mass to 100% by mass, even more preferably 10% by mass to 100% by mass, and particularly preferably 16% by volume to 100% by volume, relative to 100% by mass of the total amount of the (A) inorganic filler in the resin composition. When the amount of the (A-1) specific inorganic filler is within this range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0043] The amount (vol %) of the (A-1) specific inorganic filler is preferably 1 to 100% by volume, more preferably 5 to 100% by volume, even more preferably 8 to 100% by volume, even more preferably 15 to 100% by volume, even more preferably 50 to 100% by volume, even more preferably 70 to 100% by volume, and even more preferably 90 to 100% by volume, relative to the total amount (100% by volume) of the (A) inorganic filler in the resin composition. When the amount of the (A-1) specific inorganic filler is within this range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0044] The amount of the (A-1) specific inorganic filler is preferably set so that the ratio of the volume of voids in the (A-1) specific inorganic filler to 100% by volume of the nonvolatile components in the resin composition falls within a specific range. Hereinafter, the ratio of the volume of voids in the (A-1) specific inorganic filler may be referred to as the "volume ratio of voids in the (A-1) specific inorganic filler." The specific range of the volume ratio of voids in the (A-1) specific inorganic filler to 100% by volume of the nonvolatile components in the resin composition is preferably 0.1% by volume or more, more preferably 0.5% by volume or more, even more preferably 1.0% by volume or more, even more preferably 1.5% by volume or more, even more preferably 4% by volume or more, even more preferably 6% by volume or more, even more preferably 10% by mass or more, and preferably 50% by volume or less, more preferably 40% by volume or less, and even more preferably 30% by volume or less. When the volume fraction of the pores in the (A-1) specific inorganic filler is within the above range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and moreover, the relative dielectric constant of the insulating layer can usually be effectively reduced. The volume of the pores in the (A-1) specific inorganic filler can be calculated by multiplying the volume of the (A-1) specific inorganic filler by the porosity.

[0045] The (A) inorganic filler may further contain (A-2) an optional inorganic filler in combination with the above-mentioned (A-1) specific inorganic filler. Examples of the (A-2) optional inorganic filler include an inorganic filler that does not have internal voids (solid inorganic filler) and an inorganic filler that has voids but does not have a porosity within a specific range.

[0046] Commercially available examples of the (A-2) optional inorganic filler include "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YC100C," "YA050C," "YA050C-MJE," "YA010C," "SC2500SQ," "SO-C4," "SO-C2," and "SO-C1" manufactured by Admatechs Co., Ltd.; "UFP-30," "DAW-03," and "FB-105FD" manufactured by Denka Co., Ltd.; and "Silfil NSS-3N," "Silfil NSS-4N," and "Silfil NSS-5N" manufactured by Tokuyama Corporation. One type of (A-2) optional inorganic filler may be used alone, or two or more types may be used in combination.

[0047] The average particle size range of the optional inorganic filler (A-2) is preferably 0.01 μm or more, more preferably 0.1 μm or more, particularly preferably 0.3 μm or more, and preferably 10 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less.

[0048] (A-2) The range of the BET specific surface area of ​​the optional inorganic filler is preferably 0.1 m 2 / g or more, more preferably 0.5m 2 / g or more, particularly preferably 1m 2 / g or more, preferably 100m 2 / g or less, more preferably 70m 2 / g or less, particularly preferably 40m 2 / g or less.

[0049] The (A-2) optional inorganic filler is preferably treated with a surface treatment agent, like the (A-1) specific inorganic filler.

[0050] The proportion of voids contained in the entire (A) inorganic filler, including both the (A-1) specific inorganic filler and the (A-2) optional inorganic filler, is determined as the porosity (volume %) of the (A) inorganic filler. The porosity (volume %) of the (A) inorganic filler is a representative value representing the proportion of voids in the volume of the (A) inorganic filler on a volume basis, and is expressed as "volume of voids / volume of the (A) inorganic filler." The specific range of the porosity of the (A) inorganic filler is preferably 0.1 vol% or more, more preferably 0.5 vol% or more, even more preferably 1.0 vol% or more, even more preferably 2.0 vol% or more, even more preferably 9 vol% or more, and particularly preferably 15 vol% or more, and is preferably 90 vol% or less, more preferably 80 vol% or less, and even more preferably 70 vol% or less.

[0051] The range of the average particle size of the entire (A) inorganic filler, including both the (A-1) specific inorganic filler and the (A-2) optional inorganic filler, is preferably 0.01 μm or more, more preferably 0.1 μm or more, and particularly preferably 0.3 μm or more, and is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 3 μm or less.

[0052] The range of the BET specific surface area of ​​the entire inorganic filler (A) including both the specific inorganic filler (A-1) and the optional inorganic filler (A-2) is preferably within 1 m 2 / g or more, more preferably 2m 2 / g or more, particularly preferably 5m 2 / g or more, preferably 100m 2 / g or less, more preferably 50m 2 / g or less, particularly preferably 30m 2 / g or less.

[0053] The amount (mass %) of the (A) inorganic filler, when the nonvolatile components in the resin composition are taken as 100 mass %, is preferably 10 mass % or more, more preferably 15 mass % or more, and even more preferably 20 mass % or more, and is preferably 90 mass % or less, more preferably 85 mass % or less, and even more preferably 80 mass % or less. When the amount of the (A) inorganic filler is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0054] The amount (vol %) of the (A) inorganic filler, when the nonvolatile components in the resin composition are taken as 100% by volume, is preferably 20% by volume or more, more preferably 30% by volume or more, and even more preferably 40% by volume or more, and is preferably 90% by volume or less, more preferably 80% by volume or less, and even more preferably 70% by volume or less. When the amount of the (A) inorganic filler is within this range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0055] -(B) Curing resin- The resin composition usually contains a (B) curable resin as the component (B). The (B) curable resin can be selected from the group consisting of thermosetting resins and photocurable resins. Therefore, as the (B) curable resin, only a thermosetting resin may be used, only a photocurable resin may be used, or a combination of a thermosetting resin and a photocurable resin may be used. Furthermore, the (B) curable resin may be used alone or in combination of two or more types.

[0056] As the thermosetting resin, a resin that can be cured when heat is applied can be used. Examples of thermosetting resins include epoxy resins, phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, and radical polymerizable resins. One type of thermosetting resin may be used alone, or two or more types may be used in combination. Among these, it is preferable that the thermosetting resin contains at least one type selected from the group consisting of epoxy resins, phenolic resins, active ester resins, carbodiimide resins, and radical polymerizable resins.

[0057] In particular, from the viewpoint of improving adhesion between the insulating layer and the conductor layer formed on the insulating layer, it is preferable to use a combination of an epoxy resin and a resin capable of reacting with the epoxy resin to cure the resin composition. Hereinafter, a resin capable of reacting with an epoxy resin to cure the resin composition may be referred to as a "curing agent." Examples of curing agents include phenolic resins, active ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, and thiol resins. Among these, phenolic resins, active ester resins, cyanate resins, and carbodiimide resins are preferred, and phenolic resins, active ester resins, and carbodiimide resins are more preferred. Furthermore, one type of curing agent may be used alone, or two or more types may be used in combination.

[0058] Epoxy resin is a curable resin having an epoxy group. Examples of epoxy resins include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol novolac-type epoxy resins, phenol novolac-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, glycidylamine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, phenol aralkyl-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexane dimethanol-type epoxy resins, naphthylene ether-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, isocyanurate-type epoxy resins, and phenolphthalimidine-type epoxy resins. The epoxy resin may be used alone or in combination of two or more.

[0059] From the viewpoint of obtaining a cured product having excellent heat resistance, the epoxy resin preferably contains an epoxy resin containing an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatic rings and aromatic heterocycles. Examples of epoxy resins containing an aromatic structure include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bisphenol AF type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol novolac type epoxy resins, phenol novolac type epoxy resins, tert-butyl-catechol type epoxy resins, naphthalene type epoxy resins, naphthol type epoxy resins, anthracene type epoxy resins, bisxyleneol type epoxy resins, glycidylamine type epoxy resins having an aromatic structure, glycidyl ester type epoxy resins having an aromatic structure, cresol novolac type epoxy resins, biphenyl type epoxy resins, linear aliphatic epoxy resins having an aromatic structure, epoxy resins having a butadiene structure having an aromatic structure, alicyclic epoxy resins having an aromatic structure, heterocyclic epoxy resins, spiro ring-containing epoxy resins having an aromatic structure, cyclohexanedimethanol type epoxy resins having an aromatic structure, naphthylene ether type epoxy resins, trimethylol type epoxy resins having an aromatic structure, and tetraphenylethane type epoxy resins having an aromatic structure.

[0060] The (B) curable resin preferably contains an epoxy resin having two or more epoxy groups per molecule as the epoxy resin. The proportion of the epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to 100% by mass of the non-volatile components of the epoxy resin.

[0061] Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only a liquid epoxy resin as the epoxy resin, or may contain only a solid epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin.

[0062] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0063] Preferred liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, and epoxy resins having a butadiene structure.

[0064] Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epikote 828EL" (bisphenol A type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER807" and "1750" (bisphenol F type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycyrol type epoxy resin) manufactured by ADEKA Corporation; and "EP-3950L" and "EP-3980S" ( Examples of epoxy resins include glycidylamine epoxy resins, ADEKA's "EP-4088S" (dicyclopentadiene epoxy resin), Nippon Steel Chemical & Material's "ZX1059" (a mixture of bisphenol A and bisphenol F epoxy resins), Nagase ChemteX's "EX-721" (glycidyl ester epoxy resin), Daicel's "Celloxide 2021P" (alicyclic epoxy resin with an ester structure), Daicel's "PB-3600," Nippon Soda's "JP-100" and "JP-200" (epoxy resins with a butadiene structure), and Nippon Steel Chemical & Material's "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane epoxy resin). These may be used alone or in combination.

[0065] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0066] Preferred solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol novolac-type epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenol aralkyl-type epoxy resins, tetraphenylethane-type epoxy resins, and phenolphthalimidine-type epoxy resins.

[0067] Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); DIC Corporation's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene-type epoxy resins); and DIC Corporation's "EXA-7311." "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V", "ESN4" manufactured by Nippon Steel Chemical & Material Co., Ltd. 100V" (naphthalene-type epoxy resin); "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "Y" manufactured by Mitsubishi Chemical Corporation Examples include "X7700" (phenol aralkyl type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YX7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "WHR991S" (phenolphthalimidine type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.These may be used alone or in combination of two or more.

[0068] When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the mass ratio thereof (liquid epoxy resin:solid epoxy resin) is preferably 20:1 to 1:20, more preferably 10:1 to 1:10, and particularly preferably 7:1 to 1:7.

[0069] The epoxy equivalent of the epoxy resin is preferably in the range of 50 g / eq to 5,000 g / eq, more preferably 60 g / eq to 3,000 g / eq, even more preferably 80 g / eq to 2,000 g / eq, and particularly preferably 110 g / eq to 1,000 g / eq. The epoxy equivalent represents the mass of the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0070] The weight average molecular weight (Mw) of the epoxy resin is preferably in the range of 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0071] The amount of epoxy resin is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of epoxy resin is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0072] The amount of epoxy resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on the total mass of the resin component in the resin composition as 100% by mass. Unless otherwise specified, the resin component of the resin composition refers to the non-volatile components of the resin composition excluding the inorganic filler (A). When the amount of epoxy resin is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more typically, the dielectric constant of the insulating layer can be effectively reduced.

[0073] As the activated ester resin, compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are generally preferred. When combined with an epoxy resin, activated ester resins react with the epoxy resin to cure the resin composition, and are therefore sometimes referred to as "activated ester curing agents." The activated ester resin is preferably one obtained by the condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. From the perspective of improving heat resistance, activated ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and activated ester resins obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound are more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0074] Specifically, the active ester resin is preferably a dicyclopentadiene-type active ester resin, a naphthalene-type active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolac, or an active ester resin containing a benzoylated product of phenol novolac, and among these, at least one selected from a dicyclopentadiene-type active ester resin and a naphthalene-type active ester resin is more preferred. As the dicyclopentadiene-type active ester resin, an active ester resin containing a dicyclopentadiene-type diphenol structure is preferred.

[0075] Commercially available activated ester resins include, for example, activated ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451," "EXB9460," "EXB9460S," "EXB-8000L," "EXB-8000L-65M," "EXB-8000L-65TM," "HPC-8000L-65TM," "HPC-8000," "HPC-8000-65T," "HPC-8000H," and "HPC-8000H-65TM" (manufactured by DIC Corporation); and activated ester resins containing a naphthalene structure such as "HP-B-8151-62T," "EXB-8100L-65T," "EXB-8150-60T," and "EXB-815 Examples of activated ester resins include "EXB-9416-70BK", "HPC-8150-60T", "HPC-8150-62T", and "EXB-8" (manufactured by DIC Corporation); an activated ester resin containing phosphorus, such as "EXB9401" (manufactured by DIC Corporation); an activated ester resin which is an acetylated product of phenol novolac, such as "DC808" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin which is a benzoylated product of phenol novolac, such as "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and an activated ester resin containing a styryl group and a naphthalene structure, such as "PC1300-02-65MA" (manufactured by Air Water Inc.).

[0076] The amount of the active ester resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of the active ester resin is within the above range, recesses can be formed in the insulating layer by plasma treatment particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0077] The amount of the active ester resin is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, when the resin component in the resin composition is taken as 100% by mass. When the amount of the active ester resin is within the above range, recesses can be formed in the insulating layer by plasma treatment particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0078] When an epoxy resin and an active ester resin are used in combination, the mass ratio of the epoxy resin to the active ester resin (active ester resin / epoxy resin) is preferably within a specific range, from the viewpoint of significantly achieving the effects of the present invention. The specific range of the mass ratio (active ester resin / epoxy resin) is preferably 0.1 or more, more preferably 0.4 or more, and even more preferably 0.8 or more, and is preferably 2.0 or less, more preferably 1.6 or less, and even more preferably 1.2 or less.

[0079] The phenolic resin may be a compound having one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule. When combined with an epoxy resin, a phenolic resin may react with the epoxy resin to cure the resin composition, and is therefore sometimes referred to as a "phenolic curing agent." From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. Furthermore, from the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among these, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of achieving highly satisfactory heat resistance, water resistance, and adhesion. Specific examples of phenolic resins include "MEH-7700," "MEH-7810," and "MEH-7851" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN," "CBN," and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170," "SN-180," "SN-190," "SN-475," "SN-485," "SN-495," "SN-375," and "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "LA-7052," "LA-7054," "LA-3018," "LA-3018-50P," "LA-1356," "TD2090," and "TD-2090-60M" manufactured by DIC Corporation.

[0080] The amount of the phenolic resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of the phenolic resin is within the above range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0081] The amount of the phenolic resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, when the resin component in the resin composition is taken as 100% by mass. When the amount of the phenolic resin is within the above range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0082] As the carbodiimide resin, a compound having one or more, preferably two or more, carbodiimide structures in one molecule can be used. When combined with an epoxy resin, a carbodiimide resin can react with the epoxy resin to cure the resin composition, and therefore is sometimes called a "carbodiimide-based curing agent." Specific examples of carbodiimide resins include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane-bis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenediphenylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510" manufactured by Rhein Chemie.

[0083] The amount of the carbodiimide resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of the carbodiimide resin is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0084] The amount of the carbodiimide resin is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, when the resin component in the resin composition is taken as 100% by mass. When the amount of the carbodiimide resin is within the above range, recesses can be formed in the insulating layer by plasma treatment particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0085] The cyanate resin may be a compound having one or more, preferably two or more, cyanate groups in one molecule. When combined with an epoxy resin, the cyanate resin reacts with the epoxy resin to cure the resin composition, and therefore is sometimes called a "cyanate-based curing agent." Examples of cyanate resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate (oligo(3-methylene-1,5-phenylene cyanate)), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; multifunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine. Specific examples of cyanate resins include "PT30" and "PT60" manufactured by Lonza Japan (both of which are phenol novolac-type multifunctional cyanate resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted to form a trimer).

[0086] As the acid anhydride resin, a compound having one or more, preferably two or more, acid anhydride groups in one molecule can be used. When combined with an epoxy resin, the acid anhydride resin reacts with the epoxy resin to harden the resin composition, and is therefore sometimes called an "acid anhydride curing agent." Specific examples of acid anhydride resins include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic anhydride. Examples of suitable anhydrides include hydrates, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), and polymeric anhydrides such as styrene-maleic acid resin, which is a copolymer of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd.; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Clay Valley.

[0087] The amine resin may be a compound having one or more, preferably two or more, amino groups in one molecule. When combined with an epoxy resin, the amine resin may react with the epoxy resin to cure the resin composition, and is therefore sometimes referred to as an "amine-based curing agent." Examples of the amine resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines, with aromatic amines being preferred. The amine resin is preferably a primary amine or secondary amine, with primary amines being more preferred. Specific examples of amine resins include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxyphenyl)propionate. Examples of suitable bis(4-aminophenoxy)benzene include bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine resins include, for example, "SEIKACURE-S" manufactured by Seika Corporation; "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd.; "Epicure W" manufactured by Mitsubishi Chemical Corporation; and "DTDA" manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0088] Benzoxazine resins, when combined with epoxy resins, can react with the epoxy resin to cure the resin composition, and are therefore sometimes called "benzoxazine-based curing agents." Specific examples of benzoxazine resins include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.

[0089] Thiol resins are sometimes called "thiol-based curing agents" because they react with epoxy resins when combined with them to cure the resin composition. Examples of thiol resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0090] The active group equivalent of the curing agent is preferably in the range of 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The active group equivalent is the mass of the curing agent per equivalent of the active group.

[0091] When the number of epoxy groups in the epoxy resin is taken as 1, the number of active groups in the curing agent is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.5 or more, and preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. The "number of epoxy groups in the epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition by the epoxy equivalent. Furthermore, the "number of active groups in the curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the active group equivalent.

[0092] The amount of the curing agent is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of the curing agent is within the above range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0093] The amount of curing agent is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on 100% by mass of the resin component in the resin composition. When the amount of curing agent is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0094] The radical polymerizable resin may be a compound having an ethylenically unsaturated bond. Therefore, the radical polymerizable resin may have a radical polymerizable group containing an ethylenically unsaturated bond. Examples of the radical polymerizable group include unsaturated hydrocarbon groups such as vinyl, allyl, 3-cyclohexenyl, 3-cyclopentenyl, 2-vinylphenyl, 3-vinylphenyl, and 4-vinylphenyl; and α,β-unsaturated carbonyl groups such as acryloyl, methacryloyl, and maleimide (2,5-dihydro-2,5-dioxo-1H-pyrrol-1-yl) groups. The number of radical polymerizable groups contained in one molecule of the radical polymerizable resin may be one, but preferably two or more. One type of radical polymerizable resin may be used alone, or two or more types may be used in combination.

[0095] A preferred example of the radical polymerizable resin is a styrene-based radical polymerizable resin. The styrene-based radical polymerizable resin can be a compound having one or more, preferably two or more, vinyl groups directly bonded to an aromatic carbon atom. Examples of the styrene-based radical polymerizable resin include low-molecular-weight (molecular-weight less than 1000) styrene-based compounds such as divinylbenzene, 2,4-divinyltoluene, 2,6-divinylnaphthalene, 1,4-divinylnaphthalene, 4,4'-divinylbiphenyl, 1,2-bis(4-vinylphenyl)ethane, 2,2-bis(4-vinylphenyl)propane, and bis(4-vinylphenyl)ether; and high-molecular-weight (molecular-weight 1000 or more) styrene-based compounds such as vinylbenzyl-modified polyphenylene ether resin and styrene-divinylbenzene copolymer.

[0096] The styrene-based radical polymerizable resin is preferably a modified polyphenylene ether resin having a vinylphenyl group. The vinylphenyl group may include a 2-vinylphenyl group, a 3-vinylphenyl group, a 4-vinylphenyl group, or a group in which one or more alkyl groups are further bonded to an aromatic carbon atom of these groups. Among these, the styrene-based radical polymerizable resin is preferably a resin represented by the following formula (B-1):

[0097] [ka]

[0098] (In formula (B-1), R 11 and R 12 each independently represents an alkyl group; R 13 , R 14 , R 21 , R 22 , R 23 and R 24 each independently represents a hydrogen atom or an alkyl group; R 31 and R 32 each independently represents a vinylphenyl group; Y1 is a single bond, -C(R y )2-, -O-, -CO-, -S-, -SO-, or -SO2-; R y each independently represents a hydrogen atom or an alkyl group; Y 2 represents a single bond or an alkylene group; p represents 0 or 1; q and r each independently represent an integer of 1 or more. The q units and r units may be the same or different for each unit.

[0099] In formula (B-1), R 11 and R 12 are each independently an alkyl group, preferably a methyl group.

[0100] In formula (B-1), R 13 and R 14 are each independently a hydrogen atom or an alkyl group, and are preferably a hydrogen atom.

[0101] In formula (B-1), R 21 and R 22 each independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group, and more preferably a methyl group.

[0102] In formula (B-1), R 23 and R 24 each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom or a methyl group.

[0103] In formula (B-1), R 31 and R 32 each independently represents a vinylphenyl group.

[0104] In formula (B-1), Y 2represents a single bond or an alkylene group. The alkylene group refers to a linear, branched, and / or cyclic divalent aliphatic saturated hydrocarbon group. The alkylene group is preferably an alkylene group having 1 to 14 carbon atoms, more preferably an alkylene group having 1 to 10 carbon atoms, and particularly preferably an alkylene group having 1 to 6 carbon atoms. Examples of the alkylene group include -CH2-, -CH2-CH2-, -CH(CH3)-, -CH2-CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2-, -C(CH3)2-, and the like. Preferably, Y 2 is an alkylene group (particularly preferably -CH2-).

[0105] In formula (B-1), Y 1 is a single bond, -C(R y )2-, -O-, -CO-, -S-, -SO-, or -SO2-, and preferably represents a single bond, -C(R y ) 2- or -O-, and particularly preferably a single bond. y each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom or a methyl group.

[0106] In formula (B-1), p represents 0 or 1, and is preferably 1.

[0107] In formula (B-1), q and r each independently represent an integer of 1 or more, preferably an integer of 1-200, and more preferably an integer of 1-100.

[0108] Specific examples of the resin represented by formula (B-1) include resins represented by the following formula (B-1-1): Examples of the resin represented by formula (B-1-1) include "OPE-2St 1200" and "OPE-2St 2200" (vinylbenzyl-modified polyphenylene ether resins) manufactured by Mitsubishi Gas Chemical Company, Inc.

[0109] [ka]

[0110] Another preferred radical polymerizable resin is, for example, a maleimide radical polymerizable resin. The maleimide radical polymerizable resin can be a compound having one or more, preferably two or more, maleimide groups. The maleimide radical polymerizable resin may be an aliphatic maleimide compound containing an aliphatic amine skeleton, or an aromatic maleimide compound containing an aromatic amine skeleton. Among these, the maleimide radical polymerizable resin is preferably a resin represented by the following formula (B-2):

[0111] [ka]

[0112] (In formula (B-2), R a each independently represents a hydrogen atom or an alkyl group; Ring E, ring F, and ring G each independently represent an aromatic ring which may have a substituent; Each Z is independently a single bond, -C(R z )2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-; R z each independently represents a hydrogen atom or an alkyl group; s represents an integer equal to or greater than 1; Each t independently represents 0 or 1; Each u independently represents 0, 1, 2 or 3. The s unit, t unit, and u unit may be the same or different for each unit.

[0113] In formula (B-2), R a each independently represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0114] In formula (B-2), ring E, ring F, and ring G each independently represent an aromatic ring which may have a substituent, preferably a benzene ring which may have a substituent, more preferably a benzene ring which may be substituted with a group selected from an alkyl group and an aryl group, and particularly preferably an unsubstituted benzene ring.

[0115] In formula (B-2), each Z is independently a single bond, -C(R z )2-, -O-, -CO-, -S-, -SO-, -SO2-, -CONH-, or -NHCO-, and preferably a single bond, -C(R z )2- or -O-, and more preferably a single bond or -C(R z )2-, and particularly preferably a single bond. z each independently represents a hydrogen atom or an alkyl group, and is preferably a hydrogen atom or a methyl group.

[0116] In formula (B-2), s represents an integer of 1 or more, preferably an integer of 1 to 10, and more preferably an integer of 2 to 10.

[0117] In formula (B-2), each t independently represents 0 or 1, and is preferably 0.

[0118] In formula (B-2), each u independently represents 0, 1, 2, or 3, preferably 0, 1, or 2, more preferably 0 or 1, and particularly preferably 1.

[0119] Specific examples of the resin represented by formula (B-2) include resins represented by the following formula (B-2-1): Resins represented by formula (B-2-1) include, for example, "BMI-2300" manufactured by Daiwa Kasei Kogyo Co., Ltd. In formula (B-2-1), v represents 1 or 2.

[0120] [ka]

[0121] Still another preferred radical polymerizable resin is, for example, a (meth)acrylic radical polymerizable resin. The (meth)acrylic radical polymerizable resin may be a compound having one or more, preferably two or more, acryloyl groups and / or methacryloyl groups. Examples of the (meth)acrylic radical polymerizable resin include cyclohexane-1,4-dimethanol di(meth)acrylate, cyclohexane-1,3-dimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-octanediol di(meth)acrylate, 1,6-octanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9 ... Low molecular weight (molecular weight less than 1000) aliphatic (meth)acrylic acid ester compounds such as nanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate; dioxane glycol di(meth)acrylate, 3,6-dioxa-1,8-octanediol di(meth)acrylate, Examples of the ether-containing (meth)acrylic acid ester compounds include low molecular weight (molecular weight less than 1000) ether-containing (meth)acrylic acid ester compounds such as bis(meth)acrylate, 3,6,9-trioxaundecane-1,11-diol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene, ethoxylated bisphenol A di(meth)acrylate, and propoxylated bisphenol A di(meth)acrylate; low molecular weight (molecular weight less than 1000) isocyanurate-containing (meth)acrylic acid ester compounds such as tris(3-hydroxypropyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate; and high molecular weight (molecular weight 1000 or more) acrylic acid ester compounds such as (meth)acrylic-modified polyphenylene ether resins.Commercially available (meth)acrylic radical polymerizable resins include, for example, "A-DOG" (dioxane glycol diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., "DCP-A" (tricyclodecane dimethanol diacrylate) and "DCP" (tricyclodecane dimethanol dimethacrylate) manufactured by Kyoeisha Chemical Co., Ltd., "KAYARAD R-684" (tricyclodecane dimethanol diacrylate) and "KAYARAD R-604" (dioxane glycol diacrylate) manufactured by Nippon Kayaku Co., Ltd., and "SA9000" and "SA9000-111" (methacrylic-modified polyphenylene ether) manufactured by SABIC Innovative Plastics.

[0122] Still another preferred radical polymerizable resin is, for example, an allyl radical polymerizable resin, which can be a compound having one or more, preferably two or more, allyl groups. Examples of allyl radical polymerizable resins include aromatic carboxylic acid allyl ester compounds such as diallyl diphenate, triallyl trimellitate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl 2,6-naphthalenedicarboxylate, and diallyl 2,3-naphthalenecarboxylate; isocyanuric acid allyl ester compounds such as 1,3,5-triallyl isocyanurate and 1,3-diallyl-5-glycidyl isocyanurate; epoxy-containing aromatic allyl compounds such as 2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane; benzoxazine-containing aromatic allyl compounds such as bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane; ether-containing aromatic allyl compounds such as 1,3,5-triallyl ether benzene; and allyl silane compounds such as diallyldiphenylsilane. Commercially available allyl radical polymerizable resins include, for example, "TAIC" (1,3,5-triallyl isocyanurate) manufactured by Nippon Kasei Chemical Industry Co., Ltd., "DAD" (diallyl diphenate) manufactured by Nisshoku Techno Fine Chemical Co., Ltd., "TRIAM-705" (triallyl trimellitate) manufactured by Wako Pure Chemical Industries, Ltd., "DAND" (2,3-naphthalenecarboxylic acid diallyl) manufactured by Nippon Distillation Industry Co., Ltd., "ALP-d" (bis[3-allyl-4-(3,4-dihydro-2H-1,3-benzoxazin-3-yl)phenyl]methane) manufactured by Shikoku Chemical Industry Co., Ltd., "RE-810NM" (2,2-bis[3-allyl-4-(glycidyloxy)phenyl]propane) manufactured by Nippon Kayaku Co., Ltd., and "DA-MGIC" (1,3-diallyl-5-glycidyl isocyanurate) manufactured by Shikoku Chemical Industry Co., Ltd.

[0123] The ethylenically unsaturated bond equivalent of the radical polymerizable resin is preferably 20 g / eq. to 3000 g / eq., more preferably 50 g / eq. to 2500 g / eq., even more preferably 70 g / eq. to 2000 g / eq., and particularly preferably 90 g / eq. to 1500 g / eq. The ethylenically unsaturated bond equivalent represents the mass of the radical polymerizable resin per equivalent of the ethylenically unsaturated bond.

[0124] The weight average molecular weight (Mw) of the radical polymerizable resin is preferably 40,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less. The lower limit is not particularly limited, but can be, for example, 150 or more.

[0125] The amount of the radical polymerizable resin is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, when the nonvolatile components in the resin composition are taken as 100% by mass. When the amount of the radical polymerizable resin is within the above range, the formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0126] The amount of the radical polymerizable resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, and is preferably 99% by mass or less, and more preferably 97% by mass or less, when the resin component in the resin composition is taken as 100% by mass. When the amount of the radical polymerizable resin is within the above range, recesses can be formed in the insulating layer by plasma treatment particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0127] As the photocurable resin, a resin that can be cured when exposed to light can be used. Examples of photocurable resins include radical polymerizable resins. One type of photocurable resin may be used alone, or two or more types may be used in combination. As the radical polymerizable resin as the photocurable resin, those described in the section on thermosetting resins may be used. Furthermore, from the viewpoint of enabling development with an alkaline developer, a resin having an ethylenically unsaturated bond and a carboxyl group is preferred as the radical polymerizable resin as the photocurable resin.

[0128] The amount of (B) curable resin is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the non-volatile components in the resin composition are taken as 100% by mass. When the amount of (B) curable resin is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0129] The range of the amount of (B) curable resin, when the resin component in the resin composition is 100% by mass, is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 97% by mass or less. When the amount of (B) curable resin is within the above range, formation of recesses in the insulating layer by plasma treatment can be carried out particularly efficiently, and more usually, the relative dielectric constant of the insulating layer can be effectively reduced.

[0130] -(C)Organic particles- The resin composition may further contain optional components in combination with the components (A) and (B). For example, the resin composition may contain (C) organic particles as an optional component. The (C) organic particles as the component (C) do not include components corresponding to the components (A) and (B). The (C) organic particles are present in the resin composition in particulate form and are usually included in the cured product while maintaining their particulate form.

[0131] Since the (C) organic particles contain an organic material, they usually have higher flexibility than the (A) inorganic filler, and therefore the (C) organic particles can improve the stress resistance of the cured resin composition.

[0132] As the (C) organic particles, particles having a uniform composition throughout the particle may be used, but particles having a non-uniform composition may also be used. For example, multilayer particles having a shell portion and an internal portion formed within the shell portion are preferred. Furthermore, the multilayer particles may contain portions other than the shell portion and the internal portion. For example, the multilayer particles may further contain optional portions within the internal portion. Furthermore, for example, the multilayer particles may contain optional layers between the shell portion and the internal portion. Since the internal portion is usually covered by the shell portion, the multilayer particles can be highly dispersed in the resin composition regardless of the composition of the internal portion, thereby increasing the degree of freedom in the composition of the internal portion. Therefore, the internal portion having a composition suitable for the insulating layer can be adopted, thereby improving the characteristics of the insulating layer. The multilayer particles referred to here do not necessarily refer only to particles in which the shell portion and the internal portion are clearly distinguishable, but also include particles in which the boundary between the shell portion and the internal portion is unclear, and the internal portion does not necessarily have to be completely covered by the shell portion.

[0133] The shell portion of the multi-layer particle is usually formed by a polymer. The polymer forming the shell portion may be a homopolymer, which is a polymer of one type of monomer, or a copolymer, which is a copolymer of two or more types of monomers. The type of polymer and its monomer forming the shell portion is preferably selected to suppress aggregation of the (C) organic particles and enable good dispersion in the resin composition. The specific type depends on the composition of the (B) curable resin. Preferred examples of the monomer include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, and glycidyl (meth)acrylate; (meth)acrylic acid; N-substituted maleimides such as N-methylmaleimide and N-phenylmaleimide; maleimide; α,β-unsaturated carboxylic acids such as maleic acid and itaconic acid; aromatic vinyl compounds such as styrene, 4-vinyltoluene, and α-methylstyrene; and (meth)acrylonitrile. These monomers may be used alone or in combination of two or more.

[0134] The internal cavity of the multilayer particle preferably contains an organic material different from that contained in the shell. Multilayer particles having an internal cavity containing an organic material may have a core corresponding to the internal cavity and a shell covering the core, and are therefore sometimes referred to as "core-shell particles." In particular, the internal cavity preferably contains a rubber component. When the (C) organic particles contain multilayer particles containing a rubber component in the internal cavity, the impact resistance (impact resistance) of the insulating layer containing the cured product of the resin composition can be effectively improved. For example, the rubber component may be a resin exhibiting a modulus of elasticity of 1 GPa or less when subjected to a tensile test at a temperature of 25°C and a humidity of 40% RH in accordance with Japanese Industrial Standards (JIS K7161). Furthermore, for example, the rubber component may be a resin having a glass transition temperature of preferably 0°C or less, more preferably -10°C or less, even more preferably -20°C or less, and particularly preferably -30°C or less. The glass transition temperature can be measured by DSC (differential scanning calorimetry) at a heating rate of 10°C / min. These rubber components may be, for example, resins having one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in the molecule.

[0135] Specific examples of the rubber component include silicone-based elastomers such as polydimethylsiloxane; olefin-based thermoplastic elastomers such as polybutadiene, polyisoprene, polychlorobutadiene, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-isobutylene copolymer, acrylonitrile-butadiene copolymer, isoprene-isobutylene copolymer, isobutylene-butadiene copolymer, ethylene-propylene-diene terpolymer, and ethylene-propylene-butene terpolymer; and thermoplastic elastomers such as acrylic thermoplastic elastomers such as polypropyl(meth)acrylate, polybutyl(meth)acrylate, polycyclohexyl(meth)acrylate, and polyoctyl(meth)acrylate. Furthermore, silicone-based rubbers such as polyorganosiloxane rubbers may be mixed into the rubber component.

[0136] In the multi-layered particles containing a rubber component, the amount of the rubber component is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. There is no particular upper limit, but from the viewpoint of sufficiently covering the internal part with the shell part, it can be, for example, 95% by mass or less, 90% by mass or the like.

[0137] Multilayer particles having a built-in portion containing a rubber component can be produced, for example, by a production method including the steps of preparing core particles containing a rubber component and graft-copolymerizing a monomer component copolymerizable with the rubber component contained in the core particle to form a shell portion. Commercially available multilayer particles having a built-in portion containing a rubber component may also be used. Examples of commercially available products include "CHT" manufactured by Cheil Industries, Inc.; "B602" manufactured by UMGABS, Inc.; and "Paraloid EXL-2602," "Paraloid EXL-2603," "Paraloid EXL-2655," "Paraloid EXL-2311," "Paraloid EXL-2313," "Paraloid EXL-2315," "Paraloid KM-330," "Paraloid KM-336P," and "Paraloid KCZ- 201"; "Metablen C-223A", "Metablen E-901", "Metablen S-2001", "Metablen W-450A", and "Metablen SRK-200" manufactured by Mitsubishi Rayon Co., Ltd.; "Kane Ace M-511", "Kane Ace M-600", "Kane Ace M-400", "Kane Ace M-580", and "Kane Ace MR-01" manufactured by Kaneka Corporation; and Staphyloid "AC3832" and "AC3816N" manufactured by Aica Kogyo Co., Ltd.

[0138] The (C) organic particles may be used alone or in combination of two or more types.

[0139] The (C) organic particles may be treated with a surface treatment agent. Examples of the surface treatment agent for the (C) organic particles include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid; carboxylic acids such as acetic acid, propionic acid, butyric acid, and acrylic acid; sulfonic acids such as p-toluenesulfonic acid, ethylsulfonic acid, and dodecylbenzenesulfonic acid; phosphoric acids such as polyoxyethylene alkyl ether phosphoric acid; organic acids such as phosphonic acid and phosphinic acid; silane coupling agents such as tetraethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, and 8-(meth)acryloxyoctyltrimethoxysilane; and isocyanate compounds such as ethyl isocyanate.

[0140] The average particle size of the (C) organic particles is preferably smaller than that of the (A-1) specific inorganic filler. The specific average particle size of the (C) organic particles is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.10 μm or more, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. The average particle size of the (C) organic particles can be measured using a zeta-potential particle size distribution analyzer.

[0141] The range of the amount (mass%) of the (C) organic particles may be 0 mass% or more, and is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, even more preferably 0.2 mass% or more, and is preferably 10 mass% or less, more preferably 5 mass% or less, even more preferably 1 mass% or less, when the non-volatile components in the resin composition are taken as 100 mass%.

[0142] The range of the amount (mass%) of the (C) organic particles may be 0 mass% or more, and is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and even more preferably 1.0 mass% or more, and is preferably 20 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less, when the resin component in the resin composition is 100 mass%.

[0143] -(D) Polymer resin- The resin composition may contain a (D) polymer resin as an optional component. The (D) polymer resin as the (D) component does not include components corresponding to the (A) to (C) components. The (D) polymer resin usually exists in a state of being compatible with resin components other than the (D) polymer resin, and is included in the cured product while maintaining this compatible state. When the (D) polymer resin is used, the flexibility of the insulating layer can be increased.

[0144] The (D) polymer resin usually has a large molecular weight. Specifically, the weight average molecular weight Mw of the (D) polymer resin is preferably greater than 5,000, more preferably at least 8,000, even more preferably at least 10,000, particularly preferably at least 20,000, and is preferably at most 100,000, more preferably at most 70,000, even more preferably at most 60,000, particularly preferably at most 50,000.

[0145] Examples of the (D) polymer resin include phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. The (D) polymer resin may be used alone or in combination of two or more.

[0146] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; and "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," "YL7482," and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation.

[0147] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd.

[0148] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP, manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series, manufactured by Sekisui Chemical Co., Ltd.

[0149] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymer.

[0150] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, and polyphenylene ether-polybutadiene resins.

[0151] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0152] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0153] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0154] A specific example of the polyphenylene ether resin is NORYL SA90 manufactured by SABIC, etc. A specific example of the polyetherimide resin is ULTEM manufactured by GE, etc.

[0155] Examples of polycarbonate resins include hydroxy group-containing carbonate resins, phenolic hydroxy group-containing carbonate resins, carboxy group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, urethane group-containing carbonate resins, etc. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090," "C-2090," and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd.

[0156] A specific example of the polyether ether ketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0157] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

[0158] The range of the amount of (D) polymer resin may be 0% by mass or may be greater than 0% by mass, and is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, assuming that the non-volatile components in the resin composition are 100% by mass.

[0159] The amount of (D) polymer resin in the resin composition may be 0% by mass or more, and is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, when the resin component in the resin composition is 100% by mass.

[0160] -(E) Flame retardant- The resin composition may contain a flame retardant (E) as an optional component. The flame retardant (E) as component (E) does not include components corresponding to components (A) to (D). The flame retardant (E) can improve the flame retardancy of the insulating layer.

[0161] Examples of the (E) flame retardant include phosphazene compounds, organic phosphorus flame retardants, organic nitrogen-containing phosphorus compounds, nitrogen compounds, silicone flame retardants, metal hydroxides, etc. One type of (E) flame retardant may be used alone, or two or more types may be used in combination.

[0162] Examples of (E) flame retardants include "SPH-100," "SPS-100," "SPB-100," and "SPE-100" (phosphazenes) manufactured by Otsuka Chemical Co., Ltd.; "FP-100," "FP-110," "FP-300," and "FP-400" (phosphazenes) manufactured by Fushimi Pharmaceutical Co., Ltd.; "HCA-NQ," "HCA-HQ," and "HCA-HQ-HST" (phosphinic acid esters (containing a phenolic hydroxyl group)) manufactured by Sankosha; and "PX-200," "PX-201," "PX-202," "CR-733S," "CR-741," and "CR-747" (phosphate esters) manufactured by Daihachi Chemical Industry Co., Ltd.

[0163] The range of the amount of (E) flame retardant may be 0% by mass or more, and is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, assuming that the non-volatile components in the resin composition are 100% by mass.

[0164] The amount of (E) flame retardant in the resin composition may be 0% by mass or more, and is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, when the resin component in the resin composition is 100% by mass.

[0165] -(F) Curing accelerator- The resin composition may contain a curing accelerator (F) as an optional component. The curing accelerator (F) as component (F) does not include the components (A) to (E) described above. The curing accelerator (F) functions as a curing catalyst that accelerates the curing of the curable resin (B).

[0166] The (F) curing accelerator may be an appropriate one depending on the type of (B) curable resin. For example, when the (B) curable resin contains an epoxy resin, examples of the (F) curing accelerator that can accelerate the curing of the epoxy resin include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. One type of (F) curing accelerator may be used alone, or two or more types may be used in combination.

[0167] Examples of the phosphorus-based curing accelerator include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tetraphenylphosphonium tetra-p-tolylborate. aromatic phosphonium salts such as tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine;Dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine aromatic phosphines such as benzene, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether;

[0168] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0169] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0170] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct Examples of imidazole compounds include 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Commercially available imidazole curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" manufactured by Shikoku Chemicals Corporation; and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

[0171] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0172] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc. Commercially available amine curing accelerators may be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0173] The amount of (F) curing accelerator may be 0% by mass or more, and is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.05% by mass or more, and is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, assuming that the non-volatile components in the resin composition are 100% by mass.

[0174] The range of the amount of (F) curing accelerator may be 0% by mass or may be greater than 0% by mass, and is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, when the resin component in the resin composition is taken as 100% by mass.

[0175] -(G) Polymerization initiator- The resin composition may contain a polymerization initiator (G) as an optional component. The polymerization initiator (G) as component (G) does not include the components (A) to (F) described above. The polymerization initiator (G) may be used alone or in combination of two or more.

[0176] The type of (G) polymerization initiator can be selected depending on the type of (B) curable resin. For example, when (B) curable resin contains a radical polymerizable resin, it is preferable to use a radical polymerization initiator as the (G) polymerization initiator. Examples of radical polymerization initiators include peroxide-based radical polymerization initiators and azo-based radical polymerization initiators. Among them, peroxide-based radical polymerization initiators are preferred.

[0177] Examples of the peroxide radical polymerization initiator include hydroperoxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl peroxide compounds such as tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and diacyl peroxide compounds such as dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, and bis(4-tert-butylcyclohexyl)peroxydicarbonate. peroxyester compounds such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxyneodecanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butyl peroxylaurate, (1,1-dimethylpropyl) 2-ethylperhexanoate, tert-butyl 2-ethylperhexanoate, tert-butyl 3,5,5-trimethylperhexanoate, tert-butylperoxy-2-ethylhexyl monocarbonate, and tert-butylperoxymaleic acid; and the like.

[0178] Commercially available (G) polymerization initiators include, for example, "Perbutyl C," "Perbutyl A," "Perbutyl P," "Perbutyl L," "Perbutyl O," "Perbutyl ND," "Perbutyl Z," "Perbutyl I," "Percumyl P," "Percumyl D," "Perhexyl D," "Perhexyl A," "Perhexyl I," "Perhexyl Z," "Perhexyl ND," "Perhexyl O," and "Perhexyl PV," all manufactured by NOF Corporation.

[0179] The range of the amount of (G) polymerization initiator may be 0% by mass or more than 0% by mass, and is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, even more preferably 0.1% by mass or more, and is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, assuming that the non-volatile components in the resin composition are 100% by mass.

[0180] The range of the amount of (G) polymerization initiator may be 0% by mass or may be more than 0% by mass, and is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, when the resin component in the resin composition is 100% by mass.

[0181] -(H) Optional Additives- The resin composition may contain (H) optional additives as an optional component. The (H) optional additives do not include components corresponding to the above-mentioned components (A) to (G). Examples of the (H) optional additives include organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; triazole-based adhesion promoters, tetrazolates, and the like. Examples of the optional additives include adhesion promoters such as phenol-based adhesion promoters and triazine-based adhesion promoters; antioxidants such as hindered phenol-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers; photopolymerization initiation aids such as tertiary amines; and photosensitizers such as pyrarizones, anthracenes, coumarins, xanthones, and thioxanthones. (H) Optional additives may be used alone or in combination of two or more.

[0182] -(I) Solvent- The resin composition may further contain (I) a solvent as an optional volatile component in addition to the non-volatile components (A) to (H) described above. As the (I) solvent, an organic solvent is typically used. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, and anisole; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of suitable solvents include ether ester solvents such as ethyl acetate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (I) The solvents may be used singly or in combination of two or more.

[0183] The amount of (I) solvent is not particularly limited, but when all components in the resin composition are taken as 100% by mass, it may be, for example, 60% by mass or less, 40% by mass or less, 30% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, or may even be 0% by mass.

[0184] -Method of manufacturing resin composition- The resin composition can be produced, for example, by mixing components that can be contained in the resin composition. The above-mentioned components may be mixed in part or all at the same time, or may be mixed sequentially. In the process of mixing each component, the temperature may be appropriately set, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed in the process of mixing each component.

[0185] -Characteristics of resin composition- A cured product can be obtained by curing the resin composition described above. During the curing, heat is usually applied to the resin composition layer, and volatile components (I) such as the solvent among the components contained in the resin composition may volatilize due to the heat during curing. Therefore, the cured product of the resin composition may contain non-volatile components of the resin composition or their reaction products.

[0186] The manufacturing method according to this embodiment can manufacture a printed wiring board having an insulating layer containing the cured product. The cured product of the resin composition usually has a low density because it contains pores due to the specific inorganic filler (A-1). The specific density range of the cured product of the resin composition is preferably 1.8 g / cm. 3 or less, more preferably 1.7 g / cm 3 More preferably, 1.6 g / cm or less 3 The lower limit is not particularly limited, and is, for example, 0.6 g / cm 3 More than 0.7g / cm 3 More than 0.8g / cm 3 More than 0.9g / cm 3 A cured product having a density in this range can provide an insulating layer with excellent impact resistance.

[0187] The density of the cured resin composition can be measured using a cured product collected from the insulating layer of a printed wiring board. When the sample is a resin composition before curing, the density may be measured using a sample obtained by curing the resin composition. The curing conditions for the resin composition may be the same as those used to cure the resin composition in the method for manufacturing a printed wiring board. In one example, the density may be measured using a cured product obtained by curing the resin composition at 190°C for 90 minutes. The density may be measured at 25°C. The specific measurement method may be the method described in the Examples below.

[0188] From the viewpoint of obtaining an insulating layer having excellent impact resistance, the cured product of the resin composition preferably has a tensile modulus within a specific range. The specific range of the tensile modulus of the cured product of the resin composition is preferably 8 GPa or more, more preferably 9 GPa or more, even more preferably 10 GPa or more, and preferably 16 GPa or less, more preferably 15 GPa or less, even more preferably 14 GPa or less.

[0189] The tensile modulus of a cured resin composition can be measured using a cured product collected from the insulating layer of a printed wiring board. When the sample is a resin composition before curing, the measurement can be performed using a sample obtained by curing the resin composition. The curing conditions for the resin composition can be the same as those used to cure the resin composition in the method for manufacturing a printed wiring board. In one example, the tensile modulus can be measured using a cured product obtained by curing the resin composition at 190°C for 90 minutes. The tensile modulus can be measured at 25°C in accordance with JIS K7127. The specific measurement method can be the method described in the Examples below.

[0190] The cured product of the resin composition contains pores possessed by the specific inorganic filler (A-1), and therefore can usually have a low relative dielectric constant. In one example, the relative dielectric constant of the cured product is preferably less than 3.3, more preferably 3.2 or less, even more preferably 3.1 or less, and even more preferably 3.0 or less, with less than 3.0 being particularly preferred. There is no particular restriction on the lower limit, and it can be, for example, 1.5 or more, 2.0 or more, etc.

[0191] The dielectric constant of the cured resin composition can be measured using a cured product collected from the insulating layer of a printed wiring board. When the sample is a resin composition before curing, the measurement can be performed using a sample obtained by curing the resin composition. The curing conditions for the resin composition can be the same as those used to cure the resin composition in the method for manufacturing a printed wiring board. In one example, the dielectric constant can be measured using a cured product obtained by curing the resin composition at 190°C for 90 minutes. The dielectric constant can be measured by a cavity resonance perturbation method at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C. The specific measurement method can be the method described in the Examples below.

[0192] The cured product of the resin composition can usually have excellent impact resistance. Specifically, when an insulating layer is formed on an inner layer substrate using the cured product, peeling of the insulating layer from the inner layer substrate due to impact can be suppressed. In one example, when an insulating layer is formed on an inner layer substrate using the cured product by the method described below in the Examples to obtain evaluation substrate pieces and a drop test is performed, the percentage of evaluation substrate pieces in which peeling of the insulating layer occurs can be preferably 25% or less, more preferably 20% or less. In particular, it is even more preferable that no evaluation substrate pieces in which peeling of the insulating layer occurs can be obtained by the drop test.

[0193] <Resin sheet> The resin composition may be prepared in the form of a resin sheet for use in forming the insulating layer in step (I). The resin sheet includes a support and a resin composition layer provided on the support. The resin composition layer includes the resin composition, and preferably includes only the resin composition.

[0194] The thickness of the resin composition layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, from the viewpoint of making the printed wiring board thinner and being able to provide a cured product of the resin composition that has excellent insulating properties even when the cured product is thin. The lower limit of the thickness of the resin composition layer is not particularly limited, but may be 1 μm or more, 5 μm or more, etc.

[0195] Examples of the support include films made of plastic materials, metal foils, and release papers, with films made of plastic materials and metal foils being preferred.

[0196] When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0197] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0198] The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0199] The support may be a support with a release layer, which has a release layer on the surface that bonds with the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available products may be used as the support with a release layer, including, for example, "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, and "Uni-Peel" manufactured by Unitika Limited, which are PET films having a release layer primarily composed of an alkyd resin-based release agent.

[0200] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably 10 μm to 60 μm. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0201] In one embodiment, the resin sheet may further include an optional layer as needed. Examples of such optional layers include a protective film conforming to the support and provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, it is possible to prevent dust from adhering to the surface of the resin composition layer and scratches.

[0202] The resin sheet can be produced, for example, by preparing a liquid (varnish) resin composition as is or by dissolving the resin composition in a solvent, applying the liquid (varnish) resin composition onto a support using a coating device such as a die coater, and then drying to form a resin composition layer.

[0203] The solvent may be the same as the (I) solvent described as a component of the resin composition. One type of solvent may be used alone, or two or more types may be used in combination.

[0204] Drying may be carried out by heating, blowing hot air, or the like. Drying conditions are not particularly limited, but drying is usually carried out so that the solvent content in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the solvent in the resin composition, for example, when a resin composition containing 30% by mass to 60% by mass of solvent is used, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0205] The resin sheet can be stored by being wound up in a roll. When the resin sheet has a protective film, the resin sheet can usually be used by peeling off the protective film.

[0206] <Step (I): Formation of insulating layer> The method for manufacturing a printed wiring board according to this embodiment includes a step (I) of forming an insulating layer on an inner substrate. Typically, the step (I) includes a step (I-1) of forming a resin composition layer containing a resin composition on the inner substrate, and a step (I-2) of curing the resin composition layer.

[0207] In step (I-1), a resin composition layer is typically formed on a major surface of the inner layer substrate. The major surface of the inner layer substrate refers to the surface of the inner layer substrate on which an insulating layer is provided. For example, the resin composition layer may include applying a resin composition to the inner layer substrate and, if necessary, drying the resin composition. Preferably, in step (I-1), the inner layer substrate and a resin sheet are laminated together to form a resin composition layer on the inner layer substrate.

[0208] The lamination of the inner layer substrate and the resin sheet can be carried out so that the resin composition layer of the resin sheet is bonded to the inner layer substrate. For example, the lamination can be carried out by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as a "thermocompression bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (such as a SUS roll). Note that rather than pressing the thermocompression bonding member directly onto the resin sheet, it is preferable to press it via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently conform to the surface irregularities of the inner layer substrate.

[0209] The lamination of the inner layer substrate and the resin sheet may be carried out by a vacuum lamination method. In the vacuum lamination method, the lamination conditions are, for example, as follows. The thermocompression temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C. The thermocompression pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa. The thermocompression time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The lamination is preferably carried out under reduced pressure conditions of 26.7 hPa or less.

[0210] The lamination can be performed using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., or a batch-type vacuum pressure laminator.

[0211] After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0212] In step (I-2), the resin composition layer is cured. By curing the resin composition layer, an insulating layer containing a cured product of the resin composition can be obtained. Usually, the obtained insulating layer contains only the cured product of the resin composition. The resin composition layer can be cured by a method suitable for the resin composition, such as thermal curing or photocuring. Specific curing conditions for the resin composition layer may be the conditions usually employed when forming an insulating layer for a printed wiring board.

[0213] When a thermosetting resin composition is used, curing of the resin composition may proceed as thermal curing. Therefore, in this case, step (I-2) may include thermally curing the resin composition layer. The thermal curing conditions may vary depending on the type of resin composition. For example, the curing temperature is preferably 120°C to 240°C, more preferably 150°C to 220°C, and even more preferably 170°C to 210°C. The curing time may be preferably 5 minutes to 120 minutes, more preferably 10 minutes to 100 minutes, and even more preferably 15 minutes to 100 minutes.

[0214] When the resin composition layer is thermally cured, the method for producing a printed wiring board preferably includes preheating the resin composition layer at a temperature lower than the curing temperature before the thermal curing. For example, prior to thermal curing of the resin composition layer, the resin composition layer may be preheated at a temperature of typically 50°C to 150°C, preferably 60°C to 140°C, and more preferably 70°C to 130°C for typically 5 minutes or more, preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes.

[0215] On the other hand, when a photocurable resin composition is used, the curing of the resin composition can proceed as photocuring. Therefore, in this case, step (I-2) can include photocuring the resin composition layer. The photocuring conditions can vary depending on the type of resin composition. For example, the resin composition layer can be photocured in the irradiated area by an exposure treatment in which the resin composition layer is irradiated with actinic rays. Examples of actinic rays include ultraviolet rays, visible rays, electron beams, and X-rays, and ultraviolet rays are particularly preferred. The irradiation dose of ultraviolet rays is, for example, 10 mJ / cm. 2 ~1000mJ / cm 2 When a resin sheet provided with a support is used, exposure may be carried out through the support, or after the support has been peeled off.

[0216] In the exposure treatment, the resin composition layer may be irradiated with actinic rays through a photomask. Typically, a photomask has a light-transmitting portion that can transmit actinic rays and a light-shielding portion that can block actinic rays. Therefore, when using a photomask, selective exposure can be performed on a desired portion of the resin composition layer through the light-transmitting portion. Exposure methods using a photomask include a contact exposure method in which exposure is performed by bringing the photomask into contact with the workpiece, and a non-contact exposure method in which exposure is performed using parallel light without contact, and either method may be used.

[0217] Step (I-2) may include carrying out a development treatment after the exposure treatment. The development treatment can remove the non-photocured portions (non-exposed portions) to form holes in the insulating layer. The development is usually carried out by wet development. In wet development, a safe, stable, and easy-to-use developer is used, such as an alkaline aqueous solution, a water-based developer, or an organic solvent. Of these, a development step using an alkaline aqueous solution is preferred. Examples of development methods that can be used include spraying, swing immersion, brushing, and scraping.

[0218] Furthermore, when the resin composition layer is photocured, a post-baking treatment may be carried out as necessary after the photocuring and development. Examples of the post-baking treatment include ultraviolet irradiation treatment using a high-pressure mercury lamp and heating treatment using a clean oven. The ultraviolet irradiation treatment is carried out, for example, at 0.05 J / cm 2 ~10J / cm 2 The heat treatment can be carried out, for example, preferably at 150°C to 250°C for 20 to 180 minutes, more preferably at 160°C to 230°C for 30 to 120 minutes.

[0219] The thickness of the insulating layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less, and is preferably 1 μm or more, and more preferably 5 μm or more.

[0220] When the insulating layer is formed using a resin sheet having a support, the method for manufacturing a printed wiring board may include removing the support at an appropriate time. Typically, the support is removed after step (I-1). For example, the support may be removed between step (I-1) and step (I-2). Alternatively, for example, the support may be removed after step (I-2).

[0221] <Step (II): Formation of Mask Layer> The method for manufacturing a printed wiring board according to this embodiment may include, after step (I), step (II) of forming a mask layer on the insulating layer, if necessary. This step (II) is usually performed before step (III). The mask layer is generally formed so as to selectively cover the portions of the insulating layer other than the portions where recesses are to be formed. Therefore, the mask layer is absent in the portions of the insulating layer where recesses are to be formed, and the insulating layer may be exposed. Therefore, the plasma treatment in step (III) selectively removes the portions of the insulating layer where the mask layer is absent, thereby forming recesses having an appropriate pattern shape in those portions. Unless otherwise specified, the "pattern shape" refers to the shape as viewed in the thickness direction.

[0222] The mask layer can usually be formed using a photosensitive resist. The mask layer may be formed using, for example, a dry film provided with a resist layer containing the resist. When the mask layer is formed using a dry film, step (II) may include step (II-1) of laminating the dry film on the insulating layer, and step (II-2) of exposing and developing the dry film using a photomask to form the mask layer.

[0223] The dry film used in step (II-1) may be a film having a resist layer. The resist layer may be one that can form holes having a pattern corresponding to the recesses by exposure and development. Among these, a resist layer that is resistant to plasma treatment is preferred. Examples of such resist layers include resist layers containing resins such as novolac resins and acrylic resins. From the viewpoint of improving the processability of the recesses, the thickness of the resist layer is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. The dry film may optionally be provided with a protective layer such as a plastic film layer.

[0224] The insulating layer and the dry film are usually laminated so that the insulating layer and the resist layer are bonded together. The lamination conditions for the insulating layer and the dry film can be the same as the lamination conditions for the inner layer substrate and the resin sheet in step (I-1).

[0225] After step (II-1), step (II-2) is performed, in which the dry film is exposed and developed. The exposure in step (II-2) usually involves irradiating the dry film with active energy rays through a photomask. The photomask generally comprises a member having a light-transmitting portion that can transmit active energy rays and a light-shielding portion that can block the active energy rays. In this case, one of the light-transmitting portion and the light-shielding portion (usually the light-shielding portion) has a pattern shape identical to the pattern shape of the recesses to be formed in the insulating layer. When the dry film is irradiated with active energy rays through this photomask, the portions of the resist layer corresponding to the light-shielding portions (non-exposed portions) are not irradiated with the active energy rays, but the other portions (exposed portions) are irradiated with the active energy rays through the light-transmitting portions. Thus, a latent image having the same pattern shape as the pattern shape of the recesses is formed in the resist layer by one of the exposed and non-exposed portions (usually the non-exposed portions).

[0226] Examples of active energy rays include ultraviolet rays, visible light, electron beams, and X-rays, with ultraviolet rays being preferred. The dose and duration of ultraviolet light irradiation can be appropriately set depending on the resist layer. Examples of exposure methods include contact exposure, in which a photomask is placed in close contact with the dry film for exposure, and non-contact exposure, in which a photomask is not placed in close contact with the dry film for exposure using parallel light. When the dry film has a protective layer, the protective layer is usually peeled off before the development described below.

[0227] After exposure, development is performed to remove either the exposed or unexposed portions of the resist layer (usually the unexposed portions), thereby forming a mask layer that selectively covers the insulating layer except for the portions where recesses are to be formed. Development may be performed by either wet development or dry development. Examples of development methods include a dipping method, a puddle method, a spray method, a brushing method, and a scraping method.

[0228] <Step (III): Formation of recesses> The method for manufacturing a printed wiring board according to this embodiment includes, after step (I), step (III) of subjecting the insulating layer to plasma treatment to form a recess. In step (III), the insulating layer is scraped by the plasma treatment, thereby forming a recess in the insulating layer. The recess formed is a recessed portion formed on the surface of the insulating layer opposite the inner layer substrate, and may be a portion formed to be recessed relative to the surrounding surface. Thus, the recess has an opening on the surface of the insulating layer opposite the inner layer substrate. This recess may or may not penetrate the insulating layer. Examples of recesses that do not penetrate the insulating layer include trenches. Examples of recesses that penetrate the insulating layer include via holes. There are no limitations on the shape of this recess when viewed in the thickness direction, and it may be, for example, circular or groove-shaped.

[0229] Plasma treatment can suppress the occurrence of smears in the recesses. Therefore, the method for manufacturing a printed wiring board according to this embodiment, which includes forming recesses by plasma treatment, can omit wet desmearing, thereby reducing the environmental impact. Furthermore, plasma treatment removes particles of the inorganic filler (A) contained in the insulating layer. However, in the insulating layer containing the cured product of the resin composition described above, the inorganic filler (A) contains the specific inorganic filler (A-1), so the time required to remove the inorganic filler (A) can be shortened. Therefore, the processing speed of the plasma treatment can be improved, thereby shortening the time required to form the recesses, and thus allowing for efficient formation of the recesses.

[0230] The plasma treatment can be carried out by treating the surface of the insulating layer with plasma generated by introducing a gas into a plasma generator. Examples of plasma generation methods include microwave plasma, which generates plasma using microwaves; high-frequency plasma, which uses high-frequency waves; atmospheric pressure plasma, which is generated under atmospheric pressure; and vacuum plasma, which is generated under vacuum. Vacuum plasma, which is generated under vacuum, is preferred. Furthermore, the plasma used in step (III) is preferably RF plasma, which is excited by high frequency waves.

[0231] The gas to be converted into plasma can be one that can form recesses in the insulating layer. Examples of such gases include O2; fluorine-based gases; and inert gases such as Ar and N2. Fluorine-based gases refer to gases containing fluorine atoms, such as fluorocarbon gases such as CF4, C4F6, C4F8, CH2F2, and CHF3; SF6, and NF3. Among fluorine-based gases, C4F8 and SF6 are preferred. These gases may be used alone or in combination of two or more. Among these, gases containing one or more selected from the group consisting of O2 and fluorine-based gases are preferred. Furthermore, mixed gases containing O2 and fluorine-based gases are more preferred. Among these, mixed gases containing O2 and CF4; mixed gases containing O2, CF4, and Ar; mixed gases containing O2, C4F8, and Ar; mixed gases containing O2, SF6, and mixed gases containing O2, SF6, and Ar are even more preferred. Among these, a mixed gas containing O2 and C4F8 and a mixed gas containing O2 and SF6 are preferred, and a mixed gas containing O2 and SF6 is particularly preferred.

[0232] When plasma is generated using a mixed gas containing two or more types of gases, it is preferable to adjust the mixing ratio of these gases within an appropriate range.

[0233] For example, when a mixed gas containing O2 is used, the amount of O2 relative to 100% of the total gas amount is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more, based on sccm. The upper limit is preferably 90% or less, more preferably 80% or less, even more preferably 70% or less, and may even be 50% or less. In one example, in a mixed gas containing a combination of O2 and a fluorine-based gas, and a mixed gas containing a combination of O2, a fluorine-based gas, and an inert gas, the amount of O2 is preferably within the above range.

[0234] For example, when a mixed gas containing a fluorine-based gas is used, the amount of the fluorine-based gas relative to 100% of the total gas amount is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and may be 30% or more, 40% or more, 50% or more, or 60% or more, based on sccm. The upper limit is preferably 95% or less, more preferably 90% or less. In one example, in a mixed gas containing a combination of O2 and a fluorine-based gas, and a mixed gas containing a combination of O2, a fluorine-based gas, and an inert gas, the amount of the fluorine-based gas is preferably within the above range.

[0235] For example, when a mixed gas containing an inert gas is used, the amount of the inert gas relative to 100% of the total gas amount is preferably 1% or more, more preferably 2% or more, and even more preferably 5% or more, and is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less, based on sccm. In one example, in a mixed gas containing O, a fluorine-based gas, and an inert gas in combination, the amount of the inert gas is preferably within the above range.

[0236] For example, in a mixed gas containing O2 and a fluorine-based gas, the mixture ratio "fluorine-based gas / O2" based on sccm is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 1.0 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less. Here, "sccm" is a unit of gas flow rate, and is the amount of gas flowing per minute expressed as the volume (cm) of the gas at 0°C and 1 atm. 3 ) is indicated.

[0237] The pressure inside the chamber during plasma treatment is preferably 50 Pa or more, more preferably 75 Pa or more, even more preferably 100 Pa or more, and is preferably 300 Pa or less, more preferably 250 Pa or less, even more preferably 200 Pa or less.

[0238] The irradiation time in the plasma treatment is preferably 1 minute or more, more preferably 2 minutes or more, and even more preferably 3 minutes or more. The upper limit is not particularly limited, but is preferably 20 minutes or less, more preferably 15 minutes or less, and more preferably 10 minutes or less.

[0239] Plasma treatment can form recesses with small opening dimensions. The opening dimensions of a recess refer to the opening dimensions of the recess formed on the surface of the insulating layer opposite the inner layer substrate. For example, if the recess is a trench having a groove-like pattern, the opening dimensions refer to the width of the opening of the trench. Also, for example, if the recess is a circular via hole, the opening dimensions refer to the diameter of the opening of the via hole. The specific range of the opening dimensions is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less. The lower limit is not particularly limited, but can be 1 μm or more.

[0240] The plasma treatment allows for rapid formation of recesses. The processing speed for forming recesses can be expressed by the etching rate. The etching rate represents the thickness of the insulating layer removed per unit time, and can be calculated by dividing the depth of the recesses formed by the plasma irradiation time. In one example, the etching rate is preferably 0.4 μm / min or more, more preferably greater than 0.4 μm / min, even more preferably greater than 0.55 μm / min, and even more preferably greater than 0.7 μm / min, with the higher the rate the better.

[0241] In the past, it took a long time to remove inorganic filler particles, so when a resin composition containing a large amount of inorganic filler was used to improve properties (for example, mechanical properties such as the linear thermal expansion coefficient, and electrical properties such as dielectric properties), the etching rate tended to be particularly small. Therefore, it was difficult to improve both these properties and the etching rate. In contrast, the manufacturing method according to this embodiment has the advantage of being able to improve both the physical properties and the etching rate. From the perspective of effectively utilizing this advantage, it is preferable to carry out the manufacturing method according to this embodiment using a resin composition containing a large amount of (A) inorganic filler, such as (A-1) specific inorganic filler.

[0242] <Step (IV): Removal of Mask Layer> If a mask layer is formed on the insulating layer in step (II), the mask layer may be removed by the plasma treatment in step (III), but a portion of the mask layer may remain on the insulating layer. If the mask layer remains on the insulating layer that has been subjected to the plasma treatment in step (III), the method for manufacturing a printed wiring board may include step (IV) of removing the mask layer. The method for removing the mask layer may be an appropriate method depending on the type of mask layer. For example, the mask layer may be removed using an alkaline stripping solution such as a sodium hydroxide solution.

[0243] <Step (V): Formation of Conductive Layer> The method for producing a printed wiring board according to this embodiment preferably includes a step (V) of forming a conductor layer on an insulating layer. Step (V) may be performed after step (III). When the method for producing a printed wiring board includes step (IV), step (V) may be performed after step (IV).

[0244] The conductive material used for the conductor layer is not particularly limited. For example, the conductor layer may contain one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of alloy layers include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloys, copper-nickel alloys, and copper-titanium alloys). Among these, from the viewpoints of versatility, cost, and ease of patterning in the formation of the conductor layer, single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloys, copper-nickel alloys, or copper-titanium alloys are preferred. Single metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloys are more preferred, and single metal layers of copper are even more preferred.

[0245] The conductor layer may have a single layer structure, or a multi-layer structure including two or more single metal layers or alloy layers made of different types of metals or alloys. When the conductor layer has a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

[0246] The thickness of the conductor layer depends on the design of the circuit board, but is usually 3 μm to 35 μm, and preferably 5 μm to 30 μm.

[0247] The method for forming the conductor layer is not limited. Examples of the method for forming the conductor layer include plating, sputtering, and a combination thereof. Among these, sputtering is preferred from the viewpoints of reducing the environmental load caused by waste liquid and improving the adhesion between the insulating layer and the conductor layer.

[0248] When forming a conductor layer by sputtering, a conductor seed layer is usually formed on an insulating layer by sputtering, and then a conductor sputter layer is further formed on the conductor seed layer by sputtering. Furthermore, before forming the conductor seed layer by sputtering, the surface of the insulating layer may be cleaned by reverse sputtering. Gases used for reverse sputtering are preferably Ar gas, O2 gas, or N2 gas. When the conductor seed layer is Cu or a Cu alloy, Ar gas, O2 gas, or a mixed gas of Ar and O2 are preferred. When the conductor seed layer is Ti, Ar gas, N2 gas, or a mixed gas of Ar and N2 are preferred. When the seed layer is Cr or a Cr alloy (such as nichrome), Ar gas, O2 gas, or a mixed gas of Ar and O2 are preferred. Sputtering can be performed using various sputtering devices such as magnetron sputtering and mirror tron ​​sputtering. Examples of metals that form the conductor seed layer include Cr, Ni, Ti, and nichrome. Cr and Ti are particularly preferred. The thickness of the conductive seed layer is preferably 5 nm or more, more preferably 10 nm or more, and preferably 1000 nm or less, more preferably 500 nm or less. Examples of metals that form the conductive sputtered layer include Cu, Pt, Au, and Pd. Cu is particularly preferred. The thickness of the conductive sputtered layer is preferably 50 nm or more, more preferably 100 nm or more, and preferably 3000 nm or less, more preferably 1000 nm or less.

[0249] The conductor layer may be patterned by, for example, a subtractive method or a semi-additive method.

[0250] Furthermore, when a resin sheet having a metal foil is used as a support, the metal foil may be used to form a conductor layer. For example, when a resin sheet having a metal foil is laminated with an inner layer substrate, the metal foil may be used as a conductor layer. Specifically, a resin sheet having a metal foil may be laminated with an inner layer substrate, and the resin composition layer of the resin sheet is cured to obtain an insulating layer, thereby achieving the formation of a metal foil as a conductor layer on the insulating layer. This metal foil may be processed to have a desired pattern shape by, for example, a subtractive method, a modified semi-additive method, or the like.

[0251] When the conductor layer is formed using a metal foil, it is preferable to remove the metal foil from the portion where the recess is to be formed prior to step (III). For example, the metal foil from the portion where the recess is to be formed may be removed by etching using an etching solution such as a copper chloride etching solution or an iron chloride etching solution. This removal of the metal foil allows for smooth formation of the recess in the insulating layer by plasma treatment. The removal of the metal foil may be performed prior to step (II).

[0252] <Other matters related to printed wiring boards> In the method for manufacturing a printed wiring board according to this embodiment, the above-described steps may be repeated. For example, steps (I) to (V) may be repeated to manufacture a printed wiring board having a multilayer structure (multilayer printed wiring board) in which insulating layers and conductor layers are alternately arranged.

[0253] Furthermore, the method for manufacturing a printed wiring board according to this embodiment may further include any optional step in combination with the steps described above. For example, the method for manufacturing a printed wiring board may include a step of roughening the surface of the insulating layer after forming the insulating layer in step (III). An example of the roughening treatment is a method including contacting the surface of the insulating layer with an oxidizing agent solution. However, from the viewpoint of reducing the environmental load and effectively utilizing the advantages of this embodiment, it is preferable that the method for manufacturing a printed wiring board does not include a step of roughening the surface of the insulating layer.

[0254] <Printed wiring board> According to the above-described manufacturing method, a printed wiring board can be manufactured that includes an inner layer substrate and an insulating layer formed on the inner layer substrate. In this printed wiring board, recesses such as via holes and trenches are formed in the insulating layer. Furthermore, when the manufacturing method for a printed wiring board includes a step (V) of forming a conductor layer on the insulating layer, the manufactured printed wiring board includes the conductor layer on the insulating layer.

[0255] Since the insulating layer contains a cured product of a resin composition containing the specific inorganic filler (A-1), the insulating layer contains pores. By containing these pores, the insulating layer can usually have a low relative dielectric constant. The specific range of the relative dielectric constant of the insulating layer can be, for example, the same as the range of the relative dielectric constant of the cured product of the resin composition described above. The relative dielectric constant of the insulating layer can be measured by the method described in the Examples below.

[0256] Since the insulating layer contains pores derived from the specific inorganic filler (A-1), the insulating layer can usually have a low density. The specific density range of the insulating layer can be, for example, the same as the density range of the cured product of the resin composition described above. The density of the insulating layer can be measured by the method described in the Examples below.

[0257] The insulating layer preferably has a tensile modulus within a specific range. The range of the tensile modulus of the insulating layer may be, for example, the same as the range of the tensile modulus of the cured product of the resin composition described above. The tensile modulus of the insulating layer can be measured by the method described in the Examples below.

[0258] Furthermore, an insulating layer containing voids as described above can have excellent impact resistance. Specifically, an insulating layer formed on an inner layer substrate can suppress peeling from the inner layer substrate due to impact. In one example, when a drop test is performed on evaluation substrate pieces having an insulating layer formed on an inner layer substrate by the method described below in the Examples, the percentage of evaluation substrate pieces in which peeling of the insulating layer occurs can be preferably 25% or less, more preferably 20% or less. In particular, it is even more preferable to be able to eliminate evaluation substrate pieces in which peeling of the insulating layer occurs during the drop test.

[0259] 1 is a cross-sectional view schematically illustrating an inner substrate 100 and an insulating layer 200 of an example of a manufactured printed wiring board 10 according to one embodiment of the present invention. As shown in FIG. 1, the manufacturing method described above can manufacture a printed wiring board 10 including an inner substrate 100 and an insulating layer 200. The insulating layer 200 has a recess 300 having an opening 310 formed on a surface 200U of the insulating layer 200 opposite the inner substrate 100.

[0260] The surface of the recess 300 generally includes a side surface 300S and a bottom surface 300B. FIG. 1 shows an example in which a trench is formed as the recess 300. When the recess 300 is a trench that does not penetrate the insulating layer 200 as shown in FIG. 1, the side surface 300S and bottom surface 300B of the recess 300 are formed of a cured resin composition. When the recess is a via hole that penetrates the insulating layer, the side surface of the recess is formed of a cured resin composition, and the bottom surface of the recess is formed by the inner layer substrate. In many cases, the via hole is formed on a substrate conductor layer (not shown) of the inner layer substrate, and therefore the bottom surface of the via hole is often formed by the substrate conductor layer.

[0261] Since the insulating layer 200 contains a cured product of the resin composition, the insulating layer 200 also contains particles 400 of the (A-1) specific inorganic filler. These particles 400 contain voids 410 inside, which provides the effects of efficiently forming the recesses 300 and lowering the relative dielectric constant of the insulating layer 200.

[0262] The plasma treatment can ablate the particles 400 of the (A-1) specific inorganic filler. Therefore, the surfaces of the recess 300, such as the side surface 300S and the bottom surface 300B, can include a surface portion 420 or 430 formed by abrading the particles 400 of the (A-1) specific inorganic filler. For example, if the particles 400 are abraded by the plasma treatment, and the internal voids 410 are connected to the outside, a surface portion 420 of the inorganic compound having depressions resulting from the voids 410 can be formed. Furthermore, for example, if the particles 400 are abraded by the plasma treatment but the internal voids 410 are not connected to the outside, a surface portion 430 of the inorganic compound without depressions can be formed. Generally, since laser processing does not ablate the particles of the inorganic filler, the printed wiring board 10 including the surface portion 420 or 430 formed by abrading the particles 400 of the (A-1) specific inorganic filler as described above can be said to have a structure that can only be realized by the above-described manufacturing method.

[0263] <Semiconductor device> The above-described printed wiring board can be used to manufacture a semiconductor device. This semiconductor device includes a printed wiring board. Such a semiconductor device can be manufactured, for example, by a method including mounting a component (semiconductor chip) at a conductive point on the printed wiring board. A "conductive point" is a "point on the printed wiring board that transmits an electrical signal," and the location can be either on the surface or embedded.

[0264] Examples of semiconductor devices include various semiconductor devices used in electrical appliances (for example, computers, mobile phones, digital cameras, and televisions) and vehicles (for example, motorcycles, automobiles, trains, ships, and aircraft). [Example]

[0265] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, the temperature and pressure conditions were room temperature (25°C) and atmospheric pressure (1 atm), unless otherwise specified.

[0266] <Synthesis Example 1: Production of Hollow Inorganic Filler 1> A 20 L reactor was charged with 4 kg of methanol, 33 g of a 25% solids aqueous solution of tetramethylammonium hydroxide, 68 g of dodecyltrimethylammonium chloride, and 40 g of hexane, and the resulting mixture was stirred and dissolved to obtain a methanol solution. 12 kg of ion-exchanged water was added to the methanol solution, causing emulsified droplets of hexane to precipitate. 85 g of tetramethoxysilane was then slowly added, and the mixture was stirred at room temperature (25°C) for 5 hours, after which it was aged for 12 hours. The resulting white precipitate was then filtered using Advantec filter paper (5C), washed with 10 L of water, and dried at 100°C for 5 hours to obtain a dry powder of silica particles.

[0267] The obtained dried powder was heated to 600°C at a rate of 1°C / min with an air flow (3 L / min) in a high-speed heating electric furnace (Motoyama "SK-2535E") and calcined at 600°C for 2 hours to remove organic components, yielding hollow silica precursor particles. 50 g of these hollow silica precursor particles were transferred to an alumina crucible and calcined in the electric furnace at 1000°C in air for 72 hours to obtain hollow silica particles (average particle size 2.0 μm, porosity 20%).

[0268] 150 g of toluene, 50 g of hollow silica particles, and 5 g of N-phenyl-3-aminopropyltrimethoxysilane ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a 1 L glass container and reacted at 110°C for 12 hours with stirring to surface-treat the hollow silica particles. The reaction solution was then filtered through a membrane filter (manufactured by Advantec, PTFE, 0.2 μm pore size), and the resulting powder was washed with ethanol. The powder was then dried at 100°C for 12 hours to obtain surface-treated hollow silica particles. Hereinafter, the surface-treated hollow silica particles obtained in this manner will be referred to as "hollow inorganic filler 1."

[0269] <Synthesis Example 2: Production of Hollow Inorganic Filler 2> A 20 L reaction vessel was charged with 16 kg of water, 66 g of a 25% solids aqueous solution of tetramethylammonium hydroxide, 68 g of dodecyltrimethylammonium chloride, and 144 g of cationic acrylic polymer particles (average particle size 0.75 μm) and stirred to obtain an aqueous solution. 136 g of tetramethoxysilane was slowly added to the aqueous solution, and the mixture was stirred at room temperature (25°C) for 5 hours and then aged for 12 hours. The resulting white precipitate was then filtered through a membrane filter with a pore size of 0.2 μm, washed with 10 L of water, and dried at 100°C for 5 hours to obtain a dry powder of core-shell silica particles. The core-shell silica particles contained polymer particles as the core and silica particles as the shell.

[0270] The resulting dried powder of core-shell silica particles was heated to 600°C at a rate of 1°C / min with an airflow (3 L / min) in a high-speed heating electric furnace (Motoyama "SK-2535E") and calcined at 600°C for 2 hours to remove organic components, yielding hollow silica precursor particles. 50 g of these hollow silica precursor particles were transferred to an alumina crucible and calcined in the electric furnace at 1000°C in air for 72 hours to obtain hollow silica particles (average particle size 2.0 μm, porosity 70%).

[0271] 150 g of toluene, 50 g of hollow silica particles, and 5 g of N-phenyl-3-aminopropyltrimethoxysilane ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) were placed in a 1 L glass container and reacted at 110°C for 12 hours with stirring to surface-treat the hollow silica particles. The reaction solution was then filtered through a membrane filter (manufactured by Advantec, PTFE, 0.2 μm pore size), and the resulting powder was washed with ethanol. The powder was then dried at 100°C for 12 hours to obtain surface-treated hollow silica particles. Hereinafter, the surface-treated hollow silica particles obtained in this manner are referred to as "hollow inorganic filler 2."

[0272] Example 1 (Production of Resin Varnish 1) Biphenyl type epoxy resin (Nippon Kayaku Co., Ltd. "NC-3000-L", epoxy equivalent: approx. 269 g / eq.) 10 parts, liquid 1,4-glycidylcyclohexane (Nippon Steel Chemical & Material Co., Ltd. "ZX1658", epoxy equivalent: approx. 135 g / eq.) 10 parts, bixylenol type epoxy resin (Mitsubishi Chemical Co., Ltd. "YX4000H", epoxy equivalent: approx. 185 g / eq.) 10 parts, active ester compound (DIC 50 parts of "HPC-8000-65T" manufactured by DIC Corporation, active group equivalent weight approximately 223 g / eq., toluene solution of 65% solids), 6 parts of triazine skeleton-containing phenolic curing agent ("LA-3018-50P" manufactured by DIC Corporation, hydroxyl group equivalent weight approximately 151 g / eq., 2-methoxypropanol solution of 50% solids), 6 parts of phenoxy resin ("YX7553BH30" manufactured by Mitsubishi Chemical Corporation, 1 part of MEK and cyclohexanone solution of 30% solids). 10 parts of a carbodiimide compound (Nisshinbo Chemical's "V-03", active group equivalent weight approximately 216 g / eq., toluene solution with a solid content of 50% by mass) 10 parts of a hollow inorganic filler 1 (hollow silica particles surface-treated with a silane coupling agent, average particle size 2.0 μm, porosity 20% by volume) 176 parts of a phosphorus-based flame retardant (Sankosha's "HCA-HQ-HS", 10-(2,5-dihydroxyphenyl)-10-hydro- Resin varnish 1 was prepared by mixing 1 part of 9-oxa-10-phosphaphenanthrene-10-oxide, 1 part of rubber particles ("Staphyloid AC3816N" manufactured by Aica Kogyo Co., Ltd., average particle size 0.5 μm), 5 parts of a curing accelerator (4-dimethylaminopyridine (DMAP), MEK solution with a solids content of 5% by mass), 25 parts of methyl ethyl ketone, and 15 parts of cyclohexanone and dispersing the mixture uniformly using a high-speed rotating mixer.

[0273] (Production of resin sheet 1) A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) having a release-treated release surface was prepared as a support. A resin varnish was uniformly applied to the release surface of the support so that the thickness of the resin composition layer was 40 μm, and the film was dried at 80°C to 120°C (average 100°C) for 5 minutes to obtain a resin sheet 1 including a support and a resin composition layer.

[0274] <Example 2> The amount of hollow inorganic filler 1 was changed from 176 parts to 80 parts. In addition, 120 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. Resin varnish 2 and resin sheet 2 were produced in the same manner as in Example 1, except for the above.

[0275] Example 3 The amount of hollow inorganic filler 1 was changed from 176 parts to 32 parts. In addition, 180 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. Resin varnish 3 and resin sheet 3 were produced in the same manner as in Example 1, except for the above.

[0276] Example 4 Resin varnish 4 and resin sheet 4 were produced in the same manner as in Example 1, except that 176 parts of hollow inorganic filler 1 were replaced with 30 parts of hollow inorganic filler 2 (hollow silica particles surface-treated with a silane coupling agent, average particle size 2.0 μm, porosity 70% by volume).

[0277] <Example 5> 176 parts of hollow inorganic filler 1 was changed to 25 parts of hollow inorganic filler 2 (hollow silica particles surface-treated with a silane coupling agent, average particle size 2.0 μm, porosity 70% by volume). In addition, 120 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. Resin varnish 5 and resin sheet 5 were produced in the same manner as in Example 1, except for the above.

[0278] Example 6 176 parts of hollow inorganic filler 1 was changed to 25 parts of hollow inorganic filler 3. Here, hollow inorganic filler 3 represents hollow silica particles (average particle size 16.0 μm, porosity 80% by volume) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, 100 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. A resin varnish 6 and a resin sheet 6 were produced in the same manner as in Example 1, except for the above points.

[0279] Example 7 The amount of hollow inorganic filler 1 was changed from 176 parts to 16 parts. In addition, 200 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. Resin varnish 7 and resin sheet 7 were produced in the same manner as in Example 1, except for the above.

[0280] Example 8 Resin varnish 8 and resin sheet 8 were produced in the same manner as in Example 1, except that 176 parts of hollow inorganic filler 1 was changed to 50 parts of hollow inorganic filler 4. Hollow inorganic filler 4 represents hollow silica particles (average particle size 0.5 μm, porosity 50% by volume) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0281] Example 9 Resin varnish 9 and resin sheet 9 were produced in the same manner as in Example 1, except that 176 parts of hollow inorganic filler 1 were replaced with 20 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume).

[0282] Example 10 Resin varnish 10 and resin sheet 10 were produced in the same manner as in Example 1, except that 176 parts of hollow inorganic filler 1 was replaced with 7.5 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume).

[0283] Example 11 176 parts of hollow inorganic filler 1 was changed to 50 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume). In addition, 100 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. A resin varnish 11 and a resin sheet 11 were produced in the same manner as in Example 1, except for the above.

[0284] Example 12 176 parts of hollow inorganic filler 1 was changed to 30 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume). In addition, 100 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. A resin varnish 12 and a resin sheet 12 were produced in the same manner as in Example 1, except for the above.

[0285] Example 13 176 parts of hollow inorganic filler 1 was changed to 30 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume). In addition, 60 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. A resin varnish 13 and a resin sheet 13 were produced in the same manner as in Example 1, except for the above.

[0286] Example 14 176 parts of hollow inorganic filler 1 was changed to 20 parts of hollow inorganic filler 4 (hollow silica particles surface-treated with a silane coupling agent, average particle size 0.5 μm, porosity 50% by volume). In addition, 180 parts of spherical silica ("SO-C2" manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resin composition. A resin varnish 14 and a resin sheet 14 were produced in the same manner as in Example 1, except for the above.

[0287] Example 15 (Manufacture of resin varnish 15) Resin varnish 15 was prepared by mixing 45 parts of polyphenylmethane maleimide resin (manufactured by Daiwa Kasei Kogyo Co., Ltd., "BMI-2300," maleimide equivalent: approximately 186 g / eq.), 45 parts of radically polymerizable resin (manufactured by Mitsubishi Gas Chemical Company, Inc., "OPE-2st 1200," number average molecular weight: 1200), 10 parts of phenoxy resin (manufactured by Mitsubishi Chemical Corporation, "YX7553BH30," a 1:1 solution of MEK and cyclohexanone with a solids content of 30% by mass), 220 parts of hollow inorganic filler 1 (hollow silica particles surface-treated with a silane coupling agent, average particle size 2.0 μm, porosity 20% by volume), 10 parts of polymerization initiator (manufactured by NOF Corporation, "Perhexyl," a MEK solution with a solids content of 10% by mass), 25 parts of methyl ethyl ketone, and 15 parts of toluene, and uniformly dispersing the mixture in a high-speed rotating mixer.

[0288] (Production of resin sheet 15) A polyethylene terephthalate film ("AL5" manufactured by Lintec Corporation, thickness 38 μm) having a release-treated release surface was prepared as a support. A resin varnish was uniformly applied to the release surface of the support so that the thickness of the resin composition layer was 40 μm, and the resin varnish was dried at 80°C to 120°C (average 100°C) for 5 minutes to obtain a resin sheet 15 including a support and a resin composition layer.

[0289] <Comparative Example 1> Resin varnish 16 and resin sheet 16 were produced in the same manner as in Example 1, except that 176 parts of hollow inorganic filler 1 were replaced with 220 parts of spherical silica ("SO-C2" manufactured by Admatechs, average particle size 0.5 μm) surface-treated with a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0290] <Preparation of cured product for evaluation> A PET film ("501010" manufactured by Lintec Corporation, 38 μm thick, 240 mm square) having a release agent-treated side and an untreated side was prepared. A glass cloth-based epoxy resin double-sided copper-clad laminate ("R5715ES" manufactured by Panasonic Corporation, 0.7 mm thick, 255 mm square) was placed on the untreated side of the PET film, and the four sides were fixed with polyimide adhesive tape (10 mm wide).

[0291] The PET film with the glass cloth-based epoxy resin double-sided copper-clad laminate fixed and the above-mentioned resin sheet were laminated together so that the release agent-treated surface of the PET film and the resin composition layer of the resin sheet were bonded, and then laminated using a batch-type vacuum pressure laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.). The pressure was reduced for 30 seconds to 13 hPa or less, and then pressed for 30 seconds at 100°C and a pressure of 0.74 MPa.

[0292] The support of the resin sheet was then peeled off, and the resin composition layer was thermally cured for 90 minutes in an oven at 190°C. After thermal curing, the polyimide adhesive tape was peeled off, the glass cloth-based epoxy resin double-sided copper-clad laminate was removed, and the PET film ("501010" manufactured by Lintec Corporation) was also peeled off to obtain a sheet-like cured product for evaluation.

[0293] <Test Example 1: Density Measurement> Density of the cured product for evaluation (g / cm 3 ) was measured using a Mettler-Toledo analytical balance "XP105" (using a specific gravity measurement kit).

[0294] <Test Example 2: Measurement of Elastic Modulus> The cured products for evaluation were subjected to a tensile test at 25°C using a Tensilon universal testing machine (manufactured by A&D Co., Ltd.) in accordance with Japanese Industrial Standards (JIS K7127) to measure the tensile modulus (GPa). Measurements were performed on three test pieces, and the average value was calculated.

[0295] <Test Example 3: Measurement of relative dielectric constant Dk> The cured product for evaluation was cut to obtain an evaluation sample with a length of 80 mm and a width of 2 mm. The dielectric constant of this evaluation sample was measured at a measurement frequency of 5.8 GHz and a measurement temperature of 23°C by a cavity resonance perturbation method using an analyzer (Agilent Technologies "HP8362B"). Measurements were performed on three test pieces, and the average value was calculated. The obtained dielectric constant was evaluated according to the following criteria. Excellent: Dielectric constant less than 3.0. Acceptable: Dielectric constant is 3.0 or more and less than 3.3. Unacceptable: Dielectric constant is 3.3 or more.

[0296] <Test Example 4: Measurement of Etching Rate> (1) Preparation of copper clad laminate: As the inner layer substrate, a glass cloth-based epoxy resin double-sided copper-clad laminate with copper foil layers on both sides (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R-1515A", 255 × 340 mm size) was prepared.

[0297] (2) Laminating resin sheets: The resin sheet was laminated onto both sides of the inner layer substrate using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.) so that the resin composition layer of the resin sheet contacted the inner layer substrate. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, and then pressing the resin sheet at 100°C and a pressure of 0.74 MPa for 30 seconds. The resin sheet was then heat-pressed at 100°C and a pressure of 0.5 MPa for 60 seconds.

[0298] (3) Thermal curing of resin sheet: The inner layer substrate laminated with the resin sheet was placed in an oven at 100°C and heated for 30 minutes, then transferred to an oven at 180°C and heated for 30 minutes. The heating caused the resin composition layer to thermally cure, forming an insulating layer. The support was then peeled off to obtain a laminate A having a layer structure of insulating layer / inner layer substrate / insulating layer.

[0299] (4) Dry film patterning: A dry film (manufactured by Nikko Materials Co., Ltd., "ALPHO 20A263") was prepared, comprising a resist layer (20 μm thick) and a protective layer made of polyethylene terephthalate film. The dry film was laminated onto the surface of the insulating layer of the laminate A, so that the insulating layer and the resist layer were bonded. The lamination was carried out using a batch-type vacuum pressure laminator (manufactured by Meiki Seisakusho Co., Ltd., "MVLP-500"), with the pressure reduced for 30 seconds to 13 hPa or less, followed by pressure application at 0.1 MPa and a temperature of 70°C for 20 seconds. A glass mask with a transparent portion corresponding to the trench pattern to be formed in the resist layer was then placed on the protective layer of the dry film. A UV lamp was used to irradiate the resist layer through the glass mask at an irradiation intensity of 150 mJ / cm. 2 UV irradiation was performed at 1000 K. After UV irradiation, the protective layer was peeled off. The resist layer was developed by spraying a 1% aqueous sodium carbonate solution at 30°C at a spray pressure of 0.15 MPa for 30 seconds. After that, the resist layer was washed with water to form a mask layer as a resist layer having a trench pattern with a wiring width of 20 μm. Here, the "trench pattern" refers to holes formed in the resist layer in accordance with the planar shape of the trench to be formed in the insulating layer. Therefore, the resist layer did not cover the insulating layer in the areas where the trench pattern was formed, but selectively covered the insulating layer in areas other than the trench pattern.

[0300] (5) Plasma processing: A 20 μm wide trench was formed in the insulating layer by plasma treatment using a vacuum plasma etching device (M120W manufactured by Nissin Co., Ltd.) to obtain a printed wiring board. The plasma treatment was carried out using a CF4 / O2 mixture ratio of 1:7 (sccm) at a pressure of 120 Pa for 10 minutes.

[0301] (6) Evaluation of etching rate (processing speed) of plasma treatment: The cross section of the obtained printed wiring board was observed using a FIB-SEM composite device ("SMI3050SE" manufactured by SII Nano Technology Corporation), and the trench depth was measured. The measured depth was divided by the processing time to calculate the etching rate (μm / min). The calculated etching rate was evaluated according to the following criteria. A higher etching rate indicates more efficient trench formation. Excellent: Etching rate is greater than 0.7 μm / min. Acceptable: Etching rate is greater than 0.4 μm / min and less than 0.7 μm / min. Unacceptable: Etching rate is 0.4 μm / min or less.

[0302] <Test Example 5: Evaluation of Impact Resistance> (1) Preparation of inner layer board: Both sides of a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, Panasonic "R1515A") were etched 1 μm with a microetching agent (MEC "CZ8101") to roughen the copper surface, and an inner layer substrate was obtained.

[0303] (2) Laminating resin sheets: Using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"), the resin sheets obtained in the Examples and Comparative Examples were laminated onto both sides of the inner layer substrate so that the resin composition layer was in contact with the inner layer substrate. Lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, followed by pressure bonding at 100°C and a pressure of 0.7 MPa for 30 seconds. Next, a heat press was performed at 100°C and a pressure of 0.5 MPa for 60 seconds to obtain an intermediate substrate having a layer structure of support / resin composition layer / inner layer substrate / resin composition layer / support.

[0304] (3) Curing of the resin composition layer: The resin composition layer of the intermediate substrate was heat-cured at 180°C for 90 minutes to form an insulating layer. The support was then peeled off to obtain an evaluation substrate having a layer structure of insulating layer / internal layer substrate / insulating layer.

[0305] (4) Drop test: The evaluation substrate was cut into 10 mm x 10 mm pieces to obtain evaluation substrate pieces. The evaluation substrate pieces were fixed to the circular bottom of a cylindrical weight weighing 200 g. A drop test was then performed in which the weight was dropped from a height of 1.5 m onto a steel disk (20 mm thick, 200 mm diameter, made of SS400) with the evaluation substrate piece facing downwards.

[0306] (5) Impact resistance rating: The drop test was performed on five evaluation substrate pieces. The evaluation substrate pieces were observed after the drop test, and the impact resistance was judged according to the following criteria. Excellent impact resistance means that the insulating layer is less likely to peel off even when subjected to an impact caused by a free fall. Therefore, excellent impact resistance means that the insulating layer has high resistance to peeling due to an impact. "Excellent": No peeling was observed on any of the five substrate pieces after the drop test. "Acceptable": Peeling was observed in only one sample out of five substrate pieces after the drop test. "Fail": Peeling was observed in two or more samples out of five board pieces after the drop test.

[0307] <Results of Examples 1 to 15 and Comparative Example 1> The results of the above-mentioned Examples 1 to 15 and Comparative Example 1 are shown in the following Tables 1 to 4. In the following Tables 1 to 4, the meanings of the abbreviations are as follows. Specific gravity: Specific gravity of the solid content of each reagent [g / cm 3 ]. NV: solid content concentration.

[0308] [Table 1]

[0309] [Table 2]

[0310] [Table 3]

[0311] [Table 4]

[0312] <Microscopic observation results> Microscopic observation was performed on the trenches of the printed wiring boards produced in Examples 1 to 7 and 15. The observation results showed that trenches having the same pattern shape as the trench pattern formed in the dry film were formed in Examples 1 to 5, 7 and 15. Therefore, it was confirmed that the opening shape of the trenches could be controlled with high precision in Examples 1 to 5, 7 and 15. On the other hand, in Example 6, there was a discrepancy between the trench pattern shape and the pattern shape of the trench pattern formed on the dry film. Therefore, the accuracy of the opening shape of the formed trench was low in Example 6. This low accuracy is thought to be due to the use of a hollow inorganic filler having a larger average particle size than in the other Examples.

[0313] Furthermore, as a result of observing the trenches in Examples 1 to 7 and 15, in all Examples, surface portions formed by scraping away particles of the hollow inorganic filler were confirmed on the bottom and side surfaces of the trenches.

[0314] <Conductor layer formation test> The resist layer was removed from the printed wiring boards manufactured in Examples 1 to 7 and 15, and after drying, a conductor layer was formed of copper on the insulating layer. The conductor layer was formed by sputtering using a sputtering device and electrolytic plating.

[0315] A peel test was conducted to peel off the conductive layer formed by sputtering, and a peel strength of 1.0 kgf / cm or more was obtained. In all examples, a large force was required to peel off the conductive layer, confirming that high adhesion was obtained.

[0316] On the other hand, when a peel test was conducted to peel off the conductive layer formed by plating, Examples 1 to 7 obtained a peel strength of 1.0 kgf / cm or more, confirming high adhesion, but Example 15 obtained a peel strength of 0.3 kgf / cm as the force required for peeling, which was smaller than Examples 1 to 7. Therefore, it was confirmed that Examples 1 to 7 were superior to Example 15 in terms of adhesion to the conductive layer formed by plating.

[0317] <Verification experiment of plasma processing conditions> Hereinafter, using the resin sheet 1 manufactured in Example 1, an experiment was carried out to verify how the etching rate is affected by the gas to be converted into plasma in the plasma treatment.

[0318] Example 16 Using resin sheet 1, plasma processing and the etching rate (processing speed) of plasma processing were evaluated in Test Example 4 using the same method as in Example 1, except that the gas conditions for plasma processing were changed to use CF4 / O2 at a mixing ratio of CF4:O2 = 1:7 (sccm).

[0319] Example 17 Using the resin sheet 1, the gas conditions for plasma treatment were set to a mixture ratio of CF4 / O2 / Ar at CF 4: Plasma processing and evaluation of the etching rate (processing speed) of plasma treatment in Test Example 4 were carried out in the same manner as in Example 1, except that the flow rate was changed to O2:Ar=7:1:1 (sccm).

[0320] Example 18 Using resin sheet 1, plasma processing and the etching rate (processing speed) of plasma processing were evaluated in Test Example 4 using the same method as in Example 1, except that the gas conditions for plasma processing were changed to use C4F8 / O2 at a mixing ratio of C4F8:O2 = 7:1 (sccm).

[0321] Example 19 Using resin sheet 1, plasma processing and the etching rate (processing speed) of plasma processing were evaluated in Test Example 4 using the same method as in Example 1, except that the gas conditions for plasma processing were changed to C4F8 / O2 / Ar in a mixture ratio of C4F8:O2:Ar = 7:1:1 (sccm).

[0322] Example 20 Using resin sheet 1, plasma processing and the etching rate (processing speed) of plasma processing were evaluated in Test Example 4 using the same method as in Example 1, except that the gas conditions for plasma processing were changed to use SF6 / O2 at a mixing ratio of SF6:O2 = 7:1 (sccm).

[0323] <Results of Examples 1 and 16 to 20> The results of Examples 1 and 16 to 20 described above are shown in the table below.

[0324] [Table 5] [Explanation of symbols]

[0325] 10 Printed wiring board 100 Inner layer board 200 insulating layer 200U Insulation layer surface 300 recess 300S wall 300B bottom 310 Aperture 400 Particles of specific inorganic fillers 410 Vacancies 420 Surface formed by scraping off particles of specific inorganic filler 430 Surface formed by scraping off particles of specific inorganic filler

Claims

1. forming an insulating layer on the inner layer substrate; a step of subjecting the insulating layer to plasma treatment to form a recess; the insulating layer includes a cured product of a resin composition including an inorganic filler; The inorganic filler includes an inorganic filler having a porosity of 10% by volume or more; A method for manufacturing a printed wiring board, wherein the plasma treatment is carried out so as to remove particles of an inorganic filler contained in an insulating layer.

2. The method for manufacturing a printed wiring board according to claim 1 , further comprising the step of forming a mask layer on the insulating layer to cover areas other than the areas where the recesses are to be formed, before the step of forming the recesses in the insulating layer.

3. The method for manufacturing a printed wiring board according to claim 1 , further comprising the step of forming a conductor layer on an insulating layer.

4. The method for producing a printed wiring board according to claim 3, wherein the conductor layer is formed by a sputtering method.

5. The method for producing a printed wiring board according to claim 1 , wherein the porous inorganic filler has an average particle size of 5 μm or less.

6. The method for producing a printed wiring board according to claim 1, wherein the porosity of the porous inorganic filler is 40% by volume or more.

7. The method for producing a printed wiring board according to claim 1 , wherein the porous inorganic filler comprises an inorganic oxide.

8. The cured product of the resin composition is 1.8 g / cm ３ 10. The method of claim 1, wherein the printed wiring board has a density of:

9. A method for manufacturing a printed wiring board as described in claim 1, wherein the etching rate in the process of forming a recess in the insulating layer is 0.55 μm / min or more.

10. A printed wiring board comprising an inner layer substrate and an insulating layer formed on the inner layer substrate, the insulating layer includes a cured product of a resin composition including an inorganic filler; The inorganic filler includes an inorganic filler having a porosity of 10% by volume or more; A recess is formed in the insulating layer, A printed wiring board, wherein the surface of the recess includes a surface portion formed by scraping away particles of an inorganic filler having porosity.

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