Curable resin composition, cured product, printed circuit board comprising the cured product

Abstract

[Problem] To provide a curable resin composition having high sensitivity, capable of forming a cured article pattern having high resolution in a short time as compared with a conventional curable resin composition. [Solution] In a curable resin composition containing a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator and a photopolymerizable monomer, the concentration of a (meth) acrylic group relative to the total mass of the solid content of the curable resin composition is adjusted to 0.00070-0.00170 equivalent / g.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition, and more particularly to a curable resin composition suitable for use in forming an insulating layer by a direct imaging method requiring high-precision control, a cured product thereof, and a printed circuit board comprising the cured product. Furthermore, the present invention also relates to a method for manufacturing a printed circuit board comprising an insulating layer using the curable resin composition. [Background technology]

[0002] In recent years, with the miniaturization and reduction of electronic devices, the precision and density of electronic components such as printed circuit boards have increased. Currently, insulating layers such as solder resist layers are mainly formed by so-called photolithography. This involves applying a curable resin composition to a substrate, drying it, exposing it to light, developing it to form a pattern, and then fully curing the patterned resin by heating or light irradiation. In the manufacturing of such electronic components, there is a demand for the high-speed formation of fine patterns.

[0003] Furthermore, the remarkable advancements in exposure technology in recent years have led to the development of new exposure methods and equipment to realize such new methods, and today a variety of exposure methods and equipment exist. One such exposure method, called direct imaging, is attracting attention because, compared to conventional exposure methods that use masks, it is more economical because it does not require masks, and it can shorten the time from exposure pattern design to exposure.

[0004] On the other hand, while conventional exposure methods using masks typically involve exposure in a stationary state, direct imaging involves exposure while scanning, i.e., in a moving state. Therefore, achieving high resolution in the developed pattern requires extremely high-precision control, and as the pattern becomes finer, the exposure time increases, resulting in an increase in the time required to manufacture electronic components (cycle time). For these reasons, despite having various advantages, direct imaging has not become widespread from a technical standpoint.

[0005] However, given the expected further increase in demand for electronic devices in the future, direct imaging is required to become more widespread, and various research and development efforts are underway to that end. [Overview of the project] [Problems that the invention aims to solve]

[0006] Under these circumstances, a technical challenge exists to provide a highly sensitive curable resin composition that can form high-resolution cured material patterns in a short time.

[0007] Therefore, an object of the present invention is to provide a highly sensitive curable resin composition that can form a high-resolution cured product pattern in a short time compared to conventional curable resin compositions. Furthermore, another object of the present invention is to provide a high-resolution cured product obtained by curing such a curable resin composition, a printed circuit board comprising the cured product, and a method for manufacturing the printed circuit board. [Means for solving the problem]

[0008] As a result of diligent research, the present inventors have found that the above problems can be solved by adjusting the concentration of (meth)acrylic groups relative to the total mass of solids in a curable resin composition comprising a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer to 0.00070 to 0.00170 equivalents / g. The present invention is based on this finding. In other words, the gist of the present invention is as follows.

[0009] [1] A curable resin composition comprising a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, A curable resin composition characterized in that the concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00070 to 0.00170 equivalents / g. [2] The curable resin composition according to [1], wherein 30 to 60% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer. [3] The inorganic filler includes an inorganic filler having (meth)acrylic groups on its surface, Of the concentrations of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition, 30-60% is derived from the carboxyl group-containing resin, 5-30% is derived from the inorganic filler having the (meth)acrylic group, 30-60% are derived from the aforementioned photopolymerizable monomer. The curable resin composition described in [1] or [2]. [4] The curable resin composition according to any one of [1] to [3], wherein the concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00070 to 0.00140 equivalents / g. [5] The curable resin composition according to any one of [1] to [4], wherein 40 to 55% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer. [6] The curable resin composition according to any one of [1] to [5], wherein the concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00080 to 0.00110 equivalents / g. [7] The curable resin composition according to any one of [1] to [6], wherein 45 to 55% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer. A cured product obtained by curing any of the curable resin compositions described in [8][1] to [7]. A printed circuit board comprising the cured material described in [9][8].

[10] A method for manufacturing a printed circuit board having an insulating layer, comprising the step of forming the insulating layer by curing a curable resin composition according to any one of [1] to [7]. [Effects of the Invention]

[0010] The present invention aims to provide a highly sensitive curable resin composition that can form a high-resolution cured product pattern in a short time compared to conventional curable resin compositions. Furthermore, the present invention can provide a high-resolution cured product obtained by curing such a curable resin composition, a printed circuit board equipped with the cured product, and a method for manufacturing the printed circuit board. [Modes for carrying out the invention]

[0011] [Curable resin composition] According to one aspect of the present invention, a curable resin composition (hereinafter also referred to as "the curable resin composition of the present invention") is provided. The curable resin composition of the present invention comprises a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, and is characterized in that the concentration of (meth)acrylic groups relative to the total mass of solids of the curable resin composition is adjusted to 0.00070 to 0.00170 equivalents / g. Because the concentration of (meth)acrylic groups relative to the total mass of solids of the curable resin composition of the present invention is adjusted to a predetermined range, it has higher sensitivity to exposure and can form a cured product pattern with high resolution compared to conventional curable resin compositions. Because the curable resin composition of the present invention has high sensitivity to exposure, a high-resolution cured product pattern can be formed with a short exposure time. Therefore, even with exposure methods in motion, such as direct imaging, a high-resolution cured product pattern can be formed in a short time.

[0012] In a curable resin composition containing a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, the reason why high sensitivity (photocurability) and high resolution can be achieved by adjusting the concentration of the (meth)acrylic group to 0.00070 to 0.00170 equivalents / g with respect to the total mass of the solid content of the curable resin composition is not clear, but it is inferred as follows. That is, the radicals generated by the photopolymerization initiator absorbing ultraviolet rays undergo radical polymerization with the (meth)acrylic groups present in the curable resin composition, but it is considered that polymerization inhibition by oxygen in the atmosphere also occurs in an antagonistic manner. At that time, when the concentration of the (meth)acrylic group contained in the curable resin composition is within the above range, the inhibition by oxygen on the radical polymerization of the radicals generated from the photopolymerization initiator and the (meth)acrylic groups contained in the curable resin composition can be suppressed, and the reaction can be propagated. On the other hand, it is also possible to suppress the excessive generation of halation in the unexposed area, and it is presumed that the balance between sensitivity (photocurability) and resolution can be achieved at a high level. In the curable resin composition, the concentration of the (meth)acrylic group with respect to the total mass of the solid content of the curable resin composition is more preferably adjusted to 0.00070 to 0.00140 equivalents / g, and even more preferably to 0.00080 to 0.00110 equivalents / g. In this specification, the "(meth)acrylic group concentration" in the "curable resin composition" refers to the value calculated based on the following formula. In the following formula, the "content of resin" and the "content of components other than resin" are numerical values in terms of mass conversion. [Number]

[0013] In the above formula, the "(meth)acrylic group concentration of the resin" refers to the concentration of the total amount of (meth)acrylic groups in the resin components (carboxyl group-containing resin, thermosetting resin, photopolymerizable monomer, and other polymerizable components), and is calculated as follows. First, 0.1 g (value in mass conversion) of a sample of each resin component is precisely weighed, dissolved in 10 ml of morpholine using ultrasonic waves, 7 ml of a mixed solution of acetic acid:water = 1:1 is added, and it is heated at 98 °C for 30 minutes using an oil bath to react the morpholine. Next, the reaction solution is left at room temperature, 25 ml of methyl cellosolve and 20 ml of acetic anhydride are added to react with the unreacted morpholine, and it is left at room temperature to prepare a solution for measurement. The (meth)acrylic group concentration is calculated by titrating the obtained solution with a 0.1 N perchloric acid solution.

[0014] In the above formula, the "(meth)acrylic group concentration of components other than the resin" refers to the concentration of the total amount of (meth)acrylic groups in the components other than the above-mentioned resin components. Each component other than the resin components used in the preparation of the curable resin composition is calculated based on the (meth)acrylic group concentration of the components used during the preparation of the said component.

[0015] The concentration of (meth)acrylic groups in the curable resin composition can be adjusted by appropriately selecting the types, concentrations, mixing ratios, etc. of the above-mentioned resin components and components other than the resin. In one embodiment, the concentration of (meth)acrylic groups in the curable resin composition can be adjusted by appropriately selecting the types, concentrations, mixing ratios, etc. of the carboxyl group-containing resin, inorganic filler, and photopolymerizable monomer.

[0016] Hereinafter, each component constituting the curable resin composition of the present invention will be described in detail. (Carboxyl Group-Containing Resin) The curable resin composition of the present invention contains a carboxyl group-containing resin. Various conventionally known resins having carboxyl groups in their molecules can be used as the carboxyl group-containing resin. The inclusion of a carboxyl group-containing resin in the curable resin composition imparts alkali developability to the curable resin composition. In particular, from the viewpoint of photocurability and developability of the curable resin composition, a photosensitive carboxyl group-containing resin having an ethylenically unsaturated double bond in its molecule is preferred. The ethylenically unsaturated double bond in the molecule constituting the carboxyl group-containing resin is preferably derived from acrylic acid, methacrylic acid, or derivatives thereof. When using only a carboxyl group-containing resin without an ethylenically unsaturated double bond, the curable resin composition can be made photocurable by using a compound having multiple ethylenically unsaturated groups in its molecule, i.e., a photopolymerizable monomer, as described later. Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers). In this specification, "(meth)acrylate" is a general term referring to acrylates, methacrylates, and mixtures thereof, and the same applies to similar expressions such as "(meth)acrylic acid."

[0017] (1) A carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

[0018] (2) A carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

[0019] (3) A partially acid anhydride modified product of a reaction between diisocyanate and a bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, or biphenol type epoxy resin, and a monocarboxylic acid compound having an ethylenically unsaturated double bond such as (meth)acrylic acid, as well as a carboxyl group-containing photosensitive urethane resin obtained by polyaddition reactions of carboxyl group-containing dialcohol compounds and diol compounds.

[0020] (4) A carboxyl group-containing photosensitive urethane resin obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, to the synthesis of the resin described in (2) or (3) above, and then (meth)acrylizing the terminal (meth)acrylic.

[0021] (5) A carboxyl group-containing photosensitive urethane resin in which a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule is added to the synthesis of the resin described in (2) or (3) above, and the terminal (meth)acrylic compound is formed by adding such a compound to the end (meth)acrylic compound, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate.

[0022] (6) A carboxyl group-containing photosensitive resin obtained by reacting a bifunctional or polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chain.

[0023] (7) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0024] (8) A carboxyl group-containing polyester resin obtained by reacting a bifunctional oxetane resin with dicarboxylic acids such as adipic acid, phthalic acid, and hexahydrophthalic acid, and adding dibasic acid anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride to the resulting primary hydroxyl groups.

[0025] (9) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

[0026] (10) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the reaction product with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0027] (11) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0028] (12) A carboxyl group-containing photosensitive resin obtained by adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (11) above.

[0029] The carboxyl group-containing resins are not limited to those mentioned above and can be used in any way. Furthermore, one type of carboxyl group-containing resin may be used alone, or two or more types may be used in combination.

[0030] The acid value of the carboxyl group-containing resin is preferably 30 to 150 mg KOH / g, and more preferably 50 to 120 mg KOH / g. An acid value of 30 mg KOH / g or higher for the carboxyl group-containing resin results in good alkali developability of the curable resin composition. On the other hand, an acid value of 150 mg KOH / g or lower for the carboxyl group-containing resin suppresses dissolution of the exposed areas by the developer, and further suppresses the indistinguishable dissolution and peeling of the exposed and unexposed areas, making it easier to draw a good cured pattern.

[0031] The weight-average molecular weight of the carboxyl group-containing resin varies depending on the resin skeleton, but is generally preferably 2,000 to 100,000, more preferably 5,000 to 50,000, even more preferably 6,000 to 30,000, and particularly preferably 8,000 to 15,000. A weight-average molecular weight of 2,000 or more for the carboxyl group-containing resin suppresses the decrease in moisture resistance of the coating film after exposure of the curable resin composition, and the resulting film thinning during development. As a result, a decrease in the resolution of the cured product of the curable resin composition can be suppressed. On the other hand, a weight-average molecular weight of 100,000 or less for the carboxyl group-containing resin improves the developability and storage stability of the curable resin composition. The weight-average molecular weight of the carboxyl group-containing resin can be measured by gel permeation chromatography (GPC) (polystyrene standard). Specifically, it can be measured by GPC using the following measuring apparatus and conditions. Measuring device: Waters 2695 (manufactured by Waters) Detector: Waters 2414, manufactured by Waters, RI (Differential Refractometer) Columns: Waters HSPgelColumn, HRMB-L, 3μm, 6mm x 150mm x 2 + Waters HSPgelColumn, HR1, 3μm, 6mm x 150mm x 2 Column temperature: 40℃ RI detector setting temperature: 35℃ Developing solvent: tetrahydrofuran Flow rate: 0.5ml / min Sample volume: 10 μl Sample concentration: 0.7 wt%

[0032] The acrylic group concentration in the carboxyl group-containing resin is not particularly limited, but for example, it is 0.00050 to 0.00500 equivalents / g in terms of solid content.

[0033] The content of carboxyl group-containing resin in the curable resin composition is not particularly limited as long as the effects of the present invention are achieved, but is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, in terms of solid content. By setting the content of carboxyl group-containing resin to 5% by mass or more, the coating strength of the curable resin composition can be improved. Furthermore, by setting the content of carboxyl group-containing resin to 60% by mass or less, the viscosity of the curable resin composition becomes appropriate and the processability is improved.

[0034] In one preferred embodiment, the content of carboxyl group-containing resin in the curable resin composition is adjusted so that 30-60%, preferably 40-50%, of the total amount of (meth)acrylic groups in the curable resin composition is derived from the carboxyl group-containing resin.

[0035] (Inorganic filler) The curable resin composition of the present invention contains an inorganic filler. The inclusion of an inorganic filler in the curable resin composition is expected to improve the physical strength and other properties of the coating film of the curable resin composition. Preferably, barium sulfate, spherical silica, hydrotalcite, and talc are used as the inorganic filler. Furthermore, in order to obtain a white appearance and flame retardancy in the cured product of the curable resin composition, extender pigments consisting of metal oxides such as titanium oxide and metal hydroxides such as aluminum hydroxide can also be used as inorganic fillers. The inorganic filler may be used alone or in combination of two or more types.

[0036] Preferably, spherical silica is used as the inorganic filler. Any spherical silica that can be used as an inorganic filler for electronic materials can be used. Furthermore, the shape of the spherical silica does not have to be a perfect sphere, as long as it is spherical. Suitable spherical silica includes, for example, those with a sphericity of 0.8 or higher as measured as follows, but is not limited to this.

[0037] The sphericity of spherical silica is measured as follows: First, a photograph of the spherical silica is taken using a scanning electron microscope (SEM), and the sphericity is calculated from the area and perimeter of the particles observed in the photograph using the following formula. (Sphericity)={4π×(Area)÷(Perimeter) 2} The calculation is based on the following: Specifically, an image processing device is used to calculate the sphericity of 100 particles, and the average value of these values ​​is adopted.

[0038] The particle size of the spherical silica contained in the curable resin composition in the present invention is expressed by the particle size calculated from the equivalent spherical particle size obtained by measuring the specific surface area diameter (BET(N2)) using spherical silica before surface treatment and preparation into a curable resin composition (pre-stirring, kneading) by nitrogen adsorption method. The equivalent spherical particle size D (nm) calculated from the specific surface area diameter (BET(N2)) obtained by measuring by nitrogen adsorption method is the same as the specific surface area S (m²) measured by nitrogen adsorption method. 2 From ( / g), the specific surface area is given by the formula D(nm) = 2720 / S. The specific surface area can be measured, for example, using a fully automatic specific surface area measuring device (Macsorb® HM model-1201) manufactured by Mountec Co., Ltd. The particle size of spherical silica is not particularly limited, but is preferably on the order of nanometers (nm), for example, 1 to 1000 nm.

[0039] As spherical silica, commercially available products may be used, or products manufactured as appropriate may be used. The method for manufacturing spherical silica is not particularly limited, and methods known to those skilled in the art can be used. For example, it can be manufactured by burning silicon powder using the VMC (Vaporized Metal Combustion) method. The VMC method is a method in which a chemical flame is formed by a burner in an oxygen-containing atmosphere, and a amount of metal powder that constitutes part of the target oxide particles is added to this chemical flame in an amount that forms a dust cloud, causing deflagration to obtain oxide particles.

[0040] Examples of commercially available spherical silica include AdmaFine SO-C2, SO-E2, and AdmaNano series from Admatex Co., Ltd., SFP-20M, SFP-30M, and UFP-30 from Denka Co., Ltd., OrganoSilicaSol PGM-ST from Nissan Chemical Corporation, SeaHostar® series from Nippon Shokubai Co., Ltd., Sciqas series from Sakai Chemical Industry Co., Ltd., SG-SO100 from Kyoritsu Material Co., Ltd., HPS series (HPS-0500, HPS-1000, HPS3500, etc.) from Toagosei Co., Ltd., and MUF-1BV and MSS-T7 from Ryumori Co., Ltd.

[0041] Preferably, the inorganic filler used is one whose surface is treated to have (meth)acrylic groups. By using an inorganic filler whose surface is treated to have (meth)acrylic groups, the bond at the organic-inorganic interface in the curable resin composition can be strengthened by photoreaction-mediated covalent bonding, thereby improving the strength of the cured product of the curable resin composition.

[0042] The method for surface treatment of the inorganic filler is not particularly limited, and any known and conventional method may be used. However, it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a (meth)acrylic group, such as a coupling agent having a (meth)acrylic group as an organic group.

[0043] As coupling agents, silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents can be used. One coupling agent may be used alone, or two or more may be used in combination. Preferably, silane-based coupling agents are used. Examples of silane-based coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. It is preferable that these silane-based coupling agents are pre-immobilized on the surface of the inorganic filler by adsorption or reaction. Here, the amount of coupling agent applied to 100 parts by mass of inorganic filler is preferably 0.5 to 30 parts by mass. In this invention, reactive functional groups derived from the coupling agent applied to the inorganic filler are not included in compounds having photocurable reactive groups or thermosetting functional groups.

[0044] Furthermore, surface-treated inorganic fillers only need to be blended into the curable resin composition of the present invention in a surface-treated state. Untreated inorganic fillers and surface treatment agents may be blended separately to surface-treat the inorganic fillers in the composition, but it is preferable to blend pre-surface-treated inorganic fillers. By blending pre-surface-treated inorganic fillers, it is possible to suppress the reduction in crack resistance and other properties caused by surface treatment agents that are not consumed during the surface treatment, which may remain if they are blended separately. When pre-treating the surface, it is preferable to blend a pre-dispersion in which the inorganic filler is pre-dispersed in a solvent or curable component. It is even more preferable to pre-disperse the surface-treated inorganic filler in a solvent and then blend this pre-dispersion into the composition, or to thoroughly surface-treat the untreated inorganic filler when pre-dispersing it in a solvent and then blend this pre-dispersion into the composition.

[0045] In one preferred embodiment, the inorganic filler includes an inorganic filler having (meth)acrylic groups on its surface, and particularly preferably includes spherical silica (nanosilica) having (meth)acrylic groups on its surface and having a particle size of 100 nanometers (nm) or less.

[0046] The (meth)acrylic group concentration of the inorganic filler is not particularly limited, but is, for example, 0.00003 to 0.00300 equivalents / g. More preferably, it is 0.00005 to 0.00100 equivalents / g. By having the amount of surface treatment within the above range, the dispersibility of the inorganic filler in the carboxyl group-containing resin becomes good, and the effect of improving the strength of the cured product of the curable resin composition can be obtained.

[0047] The inorganic filler content in the curable resin composition is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, based on solid content relative to the total mass of the curable resin composition. By having an inorganic filler content of 70% by mass or less, it is possible to suppress an excessive increase in the viscosity of the curable resin composition, suppress a decrease in the coatability and moldability of the curable resin composition, and suppress the brittleness of the cured product. Furthermore, by having an inorganic filler content of 20% by mass or more, it is possible to lower the thermal expansion coefficient of the cured product of the curable resin composition, thereby mitigating the difference in thermal expansion coefficients with surrounding substrates such as wiring copper.

[0048] In one preferred embodiment, the inorganic filler content in the curable resin composition is adjusted so that 5.0 to 30%, preferably 5.5 to 10%, of the total amount of (meth)acrylic groups in the curable resin composition is derived from the inorganic filler.

[0049] (thermosetting resin) The curable resin composition of the present invention contains a thermosetting resin. The inclusion of a thermosetting resin in the curable resin composition is expected to improve its heat resistance. Any known and commonly used thermosetting resin can be used, such as melamine resin, benzoguanamine resin, melamine derivatives, amino resins such as benzoguanamine derivatives, isocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, epoxy compounds, oxetane compounds, episulfide resins, bismaleimide, carbodiimide resins, etc. Particularly preferred as the thermosetting resin is a thermosetting resin having multiple cyclic ether groups or cyclic thioether groups (hereinafter abbreviated as cyclic (thio) ether groups) in its molecule. The thermosetting resin may be used alone or in combination of two or more types.

[0050] The thermosetting resins having multiple cyclic (thio) ether groups in their molecules, as described above, are compounds having multiple 3, 4, or 5-membered cyclic (thio) ether groups in their molecules. Examples include compounds having multiple epoxy groups in their molecules, i.e., polyfunctional epoxy compounds; compounds having multiple oxetanyl groups in their molecules, i.e., polyfunctional oxetane compounds; and compounds having multiple thio ether groups in their molecules, i.e., episulfide resins.

[0051] Examples of polyfunctional epoxy compounds include epoxidized vegetable oils; bisphenol A type epoxy resins; hydroquinone type epoxy resins; bisphenol type epoxy resins; thioether type epoxy resins; brominated epoxy resins; novolac type epoxy resins; biphenol novolac type epoxy resins; bisphenol F type epoxy resins; hydrogenated bisphenol A type epoxy resins; glycidylamine type epoxy resins; hydantoin type epoxy resins; alicyclic epoxy resins; trihydroxyphenylmethane type epoxy resins; bixylenol type or biphenol type epoxy resins or mixtures thereof. Examples include, but are not limited to, bisphenol S type epoxy resins, bisphenol A novolac type epoxy resins, tetraphenyloleethane type epoxy resins, heterocyclic epoxy resins, diglycidyl phthalate resins, tetraglycidyl xylenolethane resins, naphthalene group-containing epoxy resins, epoxy resins having a dicyclopentadiene skeleton, glycidyl methacrylate copolymer epoxy resins, copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, epoxy-modified polybutadiene rubber derivatives, and CTBN-modified epoxy resins.

[0052] Examples of polyfunctional oxetane compounds include bis[(3-methyl-3-oxetanylmethoxy)methyl] ether, bis[(3-ethyl-3-oxetanylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, (3-methyl-3-oxetanyl)methyl acrylate, and (3-ethyl-3-oxetanyl)methyl acrylate. Examples include polyfunctional oxetanes such as relates, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and their oligomers or copolymers, as well as ethers of oxetane alcohols with resins having hydroxyl groups such as novolac resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring with alkyl (meth)acrylates.

[0053] Examples of compounds having multiple cyclic thioether groups in their molecules include bisphenol A-type episulfide resins. Furthermore, episulfide resins obtained by replacing the oxygen atoms in the epoxy groups of novolac-type epoxy resins with sulfur atoms using a similar synthesis method can also be used.

[0054] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylolmelamine compounds, methylolbenzoguanamine compounds, methylol glycol uryl compounds, and methylol urea compounds.

[0055] Polyisocyanate compounds can be incorporated as isocyanate compounds. Examples of polyisocyanate compounds include aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2,4-tolylene dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate; alicyclic polyisocyanates such as bicycloheptane triisocyanate; and adducts, biuret compounds, and isocyanurates of the isocyanate compounds mentioned above.

[0056] As the blocking isocyanate compound, the addition reaction product of an isocyanate compound and an isocyanate blocking agent can be used. Examples of isocyanate compounds that can react with an isocyanate blocking agent include the polyisocyanate compounds mentioned above. Examples of isocyanate blocking agents include phenol-based blocking agents, lactam-based blocking agents, active methylene-based blocking agents, alcohol-based blocking agents, oxime-based blocking agents, mercaptan-based blocking agents, acid amide-based blocking agents, imide-based blocking agents, amine-based blocking agents, imidazole-based blocking agents, and imine-based blocking agents.

[0057] Preferably, epoxy resin is used as the thermosetting resin. Examples of commercially available epoxy resins include RE-306-SA9, a phenol novolac type epoxy resin manufactured by Nippon Kayaku Co., Ltd., EPICLON® N770-75EA, a phenol novolac type epoxy resin manufactured by DIC Corporation, and YX4000, a biphenyl type epoxy resin manufactured by Mitsubishi Chemical Corporation.

[0058] The thermosetting resin content in the curable resin composition is preferably such that the number of functional groups of the thermosetting resin that react with 1 mole of carboxyl groups contained in the carboxyl group-containing resin is 0.5 to 4.5 moles, more preferably 1.0 to 3.0 moles. By having a thermosetting resin content of 0.5 moles or more, the residual carboxyl groups in the cured film of the curable resin composition are reduced, and good heat resistance, alkali resistance, electrical insulation, etc., can be obtained. On the other hand, by having a thermosetting resin content of 3.0 moles or less, the residual low molecular weight cyclic (thio) ether groups in the dried coating film are reduced, and the strength of the cured product of the curable resin composition can be ensured to be good.

[0059] (Photopolymerization initiator) The curable resin composition of the present invention contains a photopolymerization initiator. Any known photopolymerization initiator can be used. The photopolymerization initiator may be used alone or in combination of two or more.

[0060] Examples of photopolymerization initiators include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphate. Sphin oxides, bisacyl phosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinate methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenyl Monoacyl phosphine oxides such as isopropyl phosphinate and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphineate, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-propan-1-one Hydroxyacetophenones such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoins such as benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenones such as benzophenone, p-methylbenzophenone, Michla's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bisdiethylaminobenzophenone;Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1- Acetophenones such as butanone and N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone. Anthraquinones such as 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoate ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(o-benzoyloxime), etanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o- Examples include oxime esters such as acetyl oxime; titanosenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; and phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide.

[0061] Examples of commercially available photopolymerization initiators include Omnirad 379 (2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)-butan-1-one) from IGM Resins BV and IRGACURE® OXE02 from BASF Japan Ltd.

[0062] When a photopolymerization initiator other than an oxime ester-based photopolymerization initiator is used as the photopolymerization initiator, its content in the curable resin composition is not particularly limited as long as the effects of the present invention are achieved, but is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass, on a solid content basis, relative to the total mass of the curable resin composition. By setting the content of the photopolymerization initiator other than an oxime ester-based photopolymerization initiator to 0.5% by mass or more, the photocurability of the curable resin composition is improved, the cured film is less likely to peel off, and film properties such as chemical resistance are also improved. On the other hand, by setting the content of the photopolymerization initiator other than an oxime ester-based photopolymerization initiator to 5% by mass or less, an outgassing reduction effect is obtained, and furthermore, light absorption on the surface of the layer of the curable resin composition is improved, and the deep curing performance is less likely to decrease. Furthermore, when an oxime ester-based photopolymerization initiator is used as the photopolymerization initiator, its content in the curable resin composition is preferably 0.005 to 1% by mass, more preferably 0.05 to 0.5% by mass, on a solid content basis, relative to the total mass of the curable resin composition. By setting the content of the oxime ester-based photopolymerization initiator to 0.005% by mass or more, the photocurability of the curable resin composition is improved, and the heat resistance, chemical resistance, and other properties of the cured product are also improved. On the other hand, by setting the content of the oxime ester-based photopolymerization initiator to 1 part by mass or less, light absorption at the surface of the layer of the curable resin composition is improved, and the deep curing properties are less likely to decrease.

[0063] In combination with the above-mentioned photopolymerization initiator, a photoinitiator or sensitizer may be used. Examples of photoinitiators or sensitizers include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The inclusion of a thioxanthone compound as a photoinitiator or sensitizer can improve the deep curing properties of the layers of the curable resin composition. These compounds can also be used as photoinitiators, but it is preferable to use them in combination with a photoinitiator. A single photoinitiator or sensitizer may be used, or two or more may be used in combination.

[0064] Furthermore, the photopolymerization initiators, photoinitiators, and sensitizers mentioned above each absorb specific wavelengths, which may result in reduced sensitivity and cause them to function as ultraviolet absorbers. However, these are not used solely for the purpose of improving the sensitivity of curable resin compositions. By absorbing light of specific wavelengths as needed, the photoreactivity of the surface can be increased, changing the line shape and aperture of the resist to vertical, tapered, or reverse tapered shapes, while also improving the accuracy of line width and aperture diameter.

[0065] (Photopolymerizable monomer) The curable resin composition of the present invention contains a photopolymerizable monomer. When using only carboxyl group-containing resins that do not have ethylenically unsaturated double bonds as described above, the curable resin composition can be made photocurable by using a photopolymerizable monomer in combination. The photopolymerizable monomer may be used alone or in combination of two or more.

[0066] Photopolymerizable monomers are monomers having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and the like. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, trishydroxyethyl isocyanurate, etc. Polyhydric acrylates such as polyhydric alcohols or their alkylene oxide adducts or ε-caprolactone adducts; polyhydric acrylates such as phenoxyacrylate, bisphenol A diacrylate or their alkylene oxide adducts; acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, not limited to the above, acrylates obtained by directly acrylateting polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylates via diisocyanate, as well as melamine acrylate and at least one of each methacrylate corresponding to the acrylates can be appropriately selected and used. Such photopolymerizable monomers can also be used as reactive diluents. Preferably, dipentaerythritol hexaacrylate (DPHA) is used as the photopolymerizable monomer.

[0067] The concentration of (meth)acrylic groups in the photopolymerizable monomer is not particularly limited, but is, for example, 0.00100 to 0.01000 equivalents / g.

[0068] The content of photopolymerizable monomers in the curable resin composition is not particularly limited as long as the effects of the present invention are achieved, but is preferably 5 to 50 parts by mass per 100 parts by mass of carboxyl group-containing resin. When the content of photopolymerizable monomers is 5 parts by mass or more, the photocurability of the curable resin composition is good, and pattern formation is easy during alkaline development after irradiation with active energy rays. On the other hand, when the content of photopolymerizable monomers is 50 parts by mass or less, halation during exposure is less likely to occur, and good resolution can be obtained.

[0069] In one preferred embodiment, the content of photopolymerizable monomers in the curable resin composition is adjusted so that 30-60%, preferably 40-55%, and more preferably 45-55%, of the total amount of (meth)acrylic groups in the curable resin composition is derived from photopolymerizable monomers.

[0070] (Thermosetting catalyst) The curable resin composition of the present invention may optionally contain a thermosetting catalyst. Any known thermosetting catalyst can be used. Examples of thermosetting catalysts include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacate dihydrazide; and phosphorus compounds such as triphenylphosphine. The thermosetting catalyst is not limited to these, and may be an epoxy resin or an oxetane compound, or any catalyst that promotes the reaction between at least one of an epoxy group and an oxetanyl group and a carboxyl group. Furthermore, S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-2,4-diamino-S-triazine, 2-vinyl-4,6-diamino-S-triazine isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-S-triazine isocyanuric acid adduct can also be used as the thermosetting catalyst. Preferably, these compounds, which also function as adhesion promoters, are used in combination with the thermosetting catalyst. The thermosetting catalyst may be used alone or in combination of two or more. Preferably, dicyandiamide (DICY), melamine, etc., are used as the thermosetting catalyst.

[0071] The content of the thermosetting catalyst in the curable resin composition is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 15 parts by mass, per 100 parts by mass of the carboxyl group-containing resin. A thermosetting catalyst content of 0.1 parts by mass or more results in excellent heat resistance of the curable resin composition. Furthermore, a thermosetting catalyst content of 30 parts by mass or less leads to improved storage stability of the curable resin composition.

[0072] (Organic solvents) The curable resin composition may contain an organic solvent for purposes such as preparation or viscosity adjustment when applying it to a substrate or film. A well-known and commonly used organic solvent can be used as the organic solvent. Examples of organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. The organic solvent may be used alone or in combination of two or more types. Preferably, carbitol acetate (for example, Juxol CA manufactured by Dow Chemical) is used as the organic solvent.

[0073] The volatilization drying of organic solvents can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (using a heat source equipped with a steam-heated air heating method, either by bringing the hot air inside the dryer into countercurrent contact or by blowing it onto the support from a nozzle).

[0074] The content of organic solvents in the curable resin composition can be appropriately changed depending on the materials constituting the curable resin composition and the method of applying the curable resin composition to the substrate. For example, when applying the curable resin composition to a substrate by screen printing, it is preferable to adjust the solvent content so that the viscosity of the curable resin composition is 30 to 300 mPa·s. In this invention, the viscosity of the resin composition is measured by taking 0.2 ml of the resin composition and using a cone-plate viscometer TV-33H (rotor 3°' × R9.7, manufactured by Toki Sangyo Co., Ltd.) at 25°C with a rotation speed of 5 rpm (shear rate 10 -1 The viscosity value is taken after rotating for 30 seconds at s).

[0075] (Other ingredients) The curable resin composition may further contain, as needed, components such as colorants, photoinitiators, cyanate compounds, elastomers, mercapto compounds, urethane catalysts, thixonating agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper damage inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, defoamers and leveling agents such as silicone-based, fluorine-based, and polymer-based agents, silane coupling agents such as imidazole-based, thiazole-based, and triazole-based agents, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphazene compounds. These components may be those known in the field of electronic materials.

[0076] [Cured product] According to another aspect of the present invention, a cured product of the curable resin composition of the present invention (hereinafter also referred to as "the cured product of the present invention") is provided. The cured product of the present invention is a cured product formed by curing the above-described curable resin composition, and may have high resolution. Therefore, it can be suitably used as an insulating layer in electronic components such as printed circuit boards where a fine cured product pattern is required.

[0077] [Dry film] According to yet another aspect of the present invention, a dry film comprising a layer of the curable resin composition of the present invention (hereinafter also referred to as "the dry film of the present invention") is provided. That is, the curable resin composition of the present invention can be in the form of a dry film comprising a first film and a resin layer made of the curable resin composition formed on the first film. The first film in the dry film of the present invention refers to a film that is at least adhered to the resin layer when it is laminated and integrally molded by heating or the like so that the side of the resin layer formed on the dry film is in contact with a substrate such as a substrate. The first film may be peeled off from the resin layer in a process after lamination. In particular, in the dry film of the present invention, it is preferable to peel off the first film from the resin layer in a process after exposure of the resin layer. When forming a dry film of the curable resin composition of the present invention, the curable resin composition is diluted with an organic solvent as needed to adjust to an appropriate viscosity, and then applied to a first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, etc., and dried at a temperature of 50 to 130°C for 1 to 30 minutes to obtain a coating film. There are no particular restrictions on the film thickness when applying the curable resin composition, but generally, the film thickness after drying is appropriately adjusted to be in the range of 1 to 150 μm, preferably 10 to 60 μm.

[0078] The first film can be any known film without particular limitations, and for example, films made of thermoplastic resins such as polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyimide films, polyamide-imide films, polypropylene films, and polystyrene films can be suitably used. Among these, polyester films are preferred from the viewpoint of heat resistance, mechanical strength, and handling. A laminate of multiple films can also be used as the first film.

[0079] Furthermore, from the viewpoint of improving mechanical strength, the film made of the thermoplastic resin described above is preferably a film stretched in one or two axes.

[0080] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0081] After forming a resin layer of the curable resin composition of the present invention on the first film, it is preferable to further laminate a peelable second film onto the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. The second film is one that is peeled off from the resin layer before lamination when integrally forming a laminate of the first film and the resin layer on a substrate such as a substrate by heating or the like, so that the resin layer side of the laminate is in contact with the substrate. Examples of such a second film can be polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc. Furthermore, the relationship between the adhesive strength of the first film and the second film is such that when peeling off the second film, the adhesive strength between the resin layer and the second film is less than the adhesive strength between the resin layer and the first film.

[0082] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0083] In addition, in the production of the dry film of the present invention, a resin layer may be formed by applying and drying the curable resin composition of the present invention on the second film described above, and then laminating the first film on its surface. That is, in the production of the dry film of the present invention, the film to which the curable resin composition of the present invention is applied may be either the first film or the second film.

[0084] [Printed wiring board] According to yet another aspect of the present invention, a printed circuit board comprising a cured product of the present invention (hereinafter also referred to as "the printed circuit board of the present invention") is provided. The printed circuit board of the present invention comprises a cured product obtained by curing a resin layer of the curable resin composition or dry film of the present invention.

[0085] The printed circuit board of the present invention can be manufactured, for example, by following the procedure below. First, the curable resin composition of the present invention is adjusted to a viscosity suitable for the coating method using an organic solvent as needed, and applied to a substrate by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. Next, the organic solvent contained in the curable resin composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer. When using a dry film, the resin layer is bonded to the substrate using a laminator or the like so that the resin layer is in contact with the substrate, and then the first film is peeled off to form the resin layer on the substrate.

[0086] The substrates used to construct printed circuit boards include printed circuit boards with circuits pre-formed using copper, flexible printed circuit boards, and copper-clad laminates for high-frequency circuits using materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / nonwoven fabric epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, etc., as well as copper-clad laminates of all grades (FR-4, etc.), metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafers, etc.

[0087] The lamination of the dry film onto the substrate is preferably performed under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if the surface of the circuit board is uneven when a circuit-formed substrate is used, the dry film adheres closely to the circuit board, preventing the inclusion of air bubbles and improving the ability to fill in depressions on the substrate surface. The pressurizing conditions are preferably around 0.1 to 2.0 MPa, and the heating conditions are preferably 40 to 120°C.

[0088] The volatilization drying performed after applying the curable resin composition of the present invention onto a substrate can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in the dryer is brought into countercurrent contact with a heat source equipped with a steam-heated air heating method, or a method in which hot air is blown onto the support from a nozzle).

[0089] After forming a resin layer on a substrate, it is selectively exposed with active energy rays through a photomask with a predetermined pattern, if necessary, and the unexposed areas are developed with a dilute alkaline aqueous solution (e.g., 0.3-3% by mass sodium carbonate aqueous solution) to form the pattern of the cured product. In the case of a dry film, after exposure, the first film is peeled off from the dry film and developed to form a patterned cured product on the substrate. Alternatively, if the properties are not impaired, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed. Furthermore, by irradiating the cured product with active energy rays and then heat-curing it (e.g., 100-220°C), or irradiating it with active energy rays after heat-curing, or performing final finishing curing (main curing) by heat-curing alone, a cured film with excellent properties such as adhesion and hardness is formed.

[0090] The exposure equipment used for the activated energy ray irradiation described above can be any device that emits ultraviolet light in the range of 350-450 nm and is equipped with high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, mercury short-arc lamps, etc. Furthermore, direct imaging devices (for example, laser direct imaging devices that directly draw images with a laser using CAD data from a computer) can also be used. The lamp light source or laser light source of the direct imaging device can have a maximum wavelength in the range of 350-450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but is generally 10-1000 mJ / cm². 2 Preferably 20-800 mJ / cm² 2 It can be within the range of

[0091] The exposure method for the curable resin composition of the present invention is not particularly limited, and various conventional exposure methods can be appropriately selected. However, since the curable resin composition of the present invention has high sensitivity to exposure and can form a high-resolution cured material pattern with a short exposure time, it can be suitably used in exposure methods in motion, such as direct imaging.

[0092] The development methods described above can include dipping, showering, spraying, and brushing, and alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used as the developing solution. [Examples]

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" all refer to mass unless otherwise specified.

[0094] [Preparation of curable resin composition] (Synthesis of carboxyl group-containing resin A-1) Prior to preparing the curable resin composition, the carboxyl group-containing resin A-1 used in this example was prepared according to the procedure shown below. First, 220 parts (1 equivalent) of cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., ECON-104S, epoxy equivalent: 220) were placed in a four-necked flask equipped with a stirrer and reflux condenser, and 218 parts of carbitol acetate were added. The mixture was then heated and dissolved. Next, 0.46 parts of methyl hydroquinone was added as a polymerization inhibitor, and 1.38 parts of triphenylphosphine was added as a reaction catalyst. The resulting mixture was heated to 95-105°C, and 50.4 parts (0.7 equivalents) of acrylic acid and 41.5 parts (0.3 equivalents) of p-hydroxyphenethyl alcohol were gradually added dropwise, and the mixture was reacted for 16 hours. The resulting reaction product (hydroxyl group: 1.3 equivalents) was cooled to 80-90°C, 91.2 parts (0.6 equivalents) of tetrahydrophthalic anhydride were added, and the mixture was reacted for 8 hours. After cooling, the mixture was removed to obtain a solution of carboxyl group-containing resin A-1. The obtained carboxyl group-containing resin A-1 had a weight-average molecular weight of 14,000, a solid content of 65%, and an acid value of 83 mgKOH / g.

[0095] (Synthesis of carboxyl group-containing resin A-2) Prior to preparing the curable resin composition, the carboxyl group-containing resin A-2 used in this example was prepared according to the procedure shown below. First, 456 parts of bisphenol A, 228 parts of water, and 649 parts of 37% formalin were placed in a flask equipped with a condenser and a stirrer. While maintaining a temperature below 40°C, 228 parts of 25% sodium hydroxide aqueous solution were added. After the addition was complete, the mixture was reacted at 50°C for 10 hours. After the reaction was complete, the mixture was cooled to 40°C, and while maintaining a temperature below 40°C, 37.5% phosphoric acid aqueous solution was added to neutralize the mixture to pH 4. Next, the reaction mixture was allowed to stand and the aqueous layer was separated. After separating the aqueous layer, 300 parts of methyl isobutyl ketone was added and dissolved uniformly. The mixture was washed three times with 500 parts of distilled water, and the water, solvent, etc., were removed by reducing the pressure at a temperature below 50°C. The obtained polymethylol compound was dissolved in 550 parts of methanol to obtain 1230 parts of methanol solution of the polymethylol compound. A portion of the obtained methanol solution of the polymethylol compound was dried in a vacuum dryer at room temperature, and the solid content was 55.2%. Next, 500 parts of a methanol solution of the obtained polymethylol compound and 440 parts of 2,6-xylenol were uniformly dissolved at 50°C. After uniform dissolution, methanol was removed under reduced pressure at a temperature below 50°C. Then, 8 parts of oxalic acid were added and the mixture was reacted at 100°C for 10 hours. After the reaction was complete, the distillate was removed under reduced pressure at 180°C and 50 mmHg to obtain 550 parts of novolac resin A. Next, 130 parts of the obtained novolac resin A, 2.6 parts of a 50% sodium hydroxide aqueous solution, and 100 parts of toluene / methyl isobutyl ketone (mass ratio = 2 / 1) were placed in an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device. The system was purged with nitrogen while stirring, and then heated to 150°C and 8 kg / cm³. 2 Then, 45 parts of ethylene oxide were gradually introduced and the reaction was initiated. Reaction gauge pressure: 0.0 kg / cm² 2The reaction was continued for approximately 4 hours until the reaction was complete, and then cooled to room temperature. 3.3 parts of 36% hydrochloric acid aqueous solution were added to the resulting reaction solution and mixed to neutralize the sodium hydroxide. The resulting neutralization reaction product was diluted with toluene, washed three times with water, and desolvented using an evaporator to obtain an ethylene oxide adduct of novolac resin A with a hydroxyl value of 175 g / eq. This means that the obtained ethylene oxide adduct of novolac resin A had an average of 1 mole of ethylene oxide added per equivalent of phenolic hydroxyl groups. Next, 175 parts of the obtained ethylene oxide adduct of novolac resin A, 50 parts of acrylic acid, 3.0 parts of p-toluenesulfonic acid, 0.1 parts of hydroquinone monomethyl ether, and 130 parts of toluene were placed in a reactor equipped with a stirrer, thermometer, and air blowing tube. The mixture was stirred while blowing air into it, the temperature was raised to 115°C, and the reaction was continued for another 4 hours while distilling off the water produced by the reaction as an azeotropic mixture with toluene, and then cooled to room temperature. The resulting reaction solution was washed with a 5% NaCl aqueous solution, and toluene was removed by vacuum distillation. Diethylene glycol monoethyl ether acetate was then added to obtain an acrylate resin solution with a solid content of 68%. Next, 312 parts of the obtained acrylate resin solution, 0.1 parts of hydroquinone monomethyl ether, and 0.3 parts of triphenylphosphine were placed in a four-necked flask equipped with a stirrer and reflux condenser. The mixture was heated to 110°C, 45 parts of tetrahydrophthalic anhydride were added, and the mixture was reacted for 4 hours. After cooling, the mixture was removed to obtain a solution of carboxyl group-containing resin A-2. The obtained carboxyl group-containing resin A-2 had a weight-average molecular weight of 12,000, a solid content of 70%, and an acid value of 65 mgKOH / g.

[0096] (Synthesis of carboxyl group-containing resin A-3) Prior to preparing the curable resin composition, the carboxyl group-containing resin A-3 used in this example was prepared according to the procedure shown below. First, 119.4 parts of novolac-type cresol resin (Shounol CRG951, manufactured by Showa Denko K.K., OH equivalent: 119.4), 1.19 parts of potassium hydroxide, and 119.4 parts of toluene were placed in an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device. The system was then purged with nitrogen while stirring, and the temperature was increased. Next, 63.8 parts of propylene oxide were gradually added dropwise, at a temperature of 125-132°C and a pressure of 0-4.8 kg / cm². 2 The mixture was reacted for 16 hours. The system was then cooled to room temperature, and 1.56 parts of 89% by mass phosphoric acid were added to the resulting reaction solution and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac-type cresol resin with a non-volatile content of 62.1% and a hydroxyl value of 182.2 g / eq. The resulting novolac-type cresol resin had an average of 1.08 moles of alkylene oxide added per equivalent of phenolic hydroxyl groups. Next, 293.0 parts of the obtained alkylene oxide reaction solution of novolac-type cresol resin, 43.2 parts of acrylic acid, 11.53 parts of methanesulfonic acid, 0.18 parts of methylhydroquinone, and 252.9 parts of toluene were placed in a reactor equipped with a stirrer, thermometer, and air blowing tube, and the mixture was reacted at a temperature of 110°C for 12 hours while blowing air at a rate of 10 ml / min and stirring. The water produced by the reaction was distilled off as an azeotropic mixture with toluene, with 12.6 parts of water being distilled off. The system was then cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts of 15% aqueous sodium hydroxide solution and washed with water. Next, toluene was removed by distillation using an evaporator, replacing it with 118.1 parts of diethylene glycol monoethyl ether acetate (carbitol acetate) to obtain a novolac-type acrylate resin solution. Next, 332.5 parts of the obtained novolac-type acrylate resin solution and 1.22 parts of triphenylphosphine were placed in a reactor equipped with a stirrer, thermometer, and air blowing tube, and 60.8 parts of tetrahydrophthalic anhydride were gradually added while stirring and blowing air at a rate of 10 ml / min. The reaction was carried out at a temperature of 95-101°C for 6 hours, and after cooling, it was removed to obtain a solution of carboxyl group-containing resin A-3. The obtained carboxyl group-containing resin A-3 had a weight-average molecular weight of 3,000, a solid content of 65%, and an acid value of 88 mgKOH / g.

[0097] (Preparation of (meth)acrylic group-containing surface-treated inorganic filler B'-1) The (meth)acrylic group-containing surface-treated inorganic filler B'-1 used in this example was prepared according to the procedure shown below. Specifically, 70 g of spherical silica (SFP-30M, manufactured by Denka Co., Ltd., 100% solids content), 27 g of PMA (propylene glycol monomethyl ether acetate) as a solvent, and 3 g of KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent were uniformly dispersed to obtain the silica solvent-dispersed (meth)acrylic group-containing surface-treated inorganic filler B'-1.

[0098] (Preparation of (meth)acrylic group-containing surface-treated inorganic filler B'-2) The (meth)acrylic group-containing surface-treated inorganic filler B'-2 used in this embodiment was prepared according to the procedure shown below. Specifically, 233 g of spherical silica (organo-silica sol PGM-ST, manufactured by Nissan Chemical Corporation, with a solid content of 30%) and 3 g of KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd., as a silane coupling agent were uniformly dispersed to obtain the silica solvent-dispersed (meth)acrylic group-containing surface-treated inorganic filler B'-2.

[0099] (Preparation of (meth)acrylic group-containing surface-treated inorganic filler B'-3) The (meth)acrylic group-containing surface-treated inorganic filler B'-3 used in this embodiment was prepared according to the procedure shown below. Specifically, 233 g of spherical silica (organo-silica sol PGM-ST, manufactured by Nissan Chemical Corporation, with a solid content of 30%) and 36 g of KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd., as a silane coupling agent were uniformly dispersed to obtain the silica solvent-dispersed (meth)acrylic group-containing surface-treated inorganic filler B'-3.

[0100] Each component shown in Table 1 was mixed in the amounts shown in the table, pre-mixed using a stirrer, and then kneaded using a three-roll mill to prepare the curable resin compositions for Examples 1-13 and Comparative Examples 1-2. Details of each component in Table 1 are as follows. Note that the (meth)acrylic group concentration of each component other than each carboxyl group-containing resin and each inorganic filler was 0 equivalents / g. Carboxyl group-containing resin A-1: ​​Carboxyl group-containing resin obtained by the synthesis of the carboxyl group-containing resin A-1 described above. Carboxyl group-containing resin A-2: Carboxyl group-containing resin obtained by the synthesis of the above-mentioned carboxyl group-containing resin A-2 Carboxyl group-containing resin A-3: Carboxyl group-containing resin obtained by the synthesis of the above-mentioned carboxyl group-containing resin A-3 Inorganic filler B-1: Untreated organosilica sol PGM-ST manufactured by Nissan Chemical Corporation (particle size 12 nm, (meth)acrylic group concentration 0 equivalents / g) Inorganic filler B-2: Barium sulfate B-30 manufactured by Sakai Chemical Industry Co., Ltd. (acrylic group concentration 0 equivalents / g) Inorganic filler B'-1: Solvent dispersion of silica surface-treated with the methacrylate silane prepared above (particle size 550 nm, (meth)acrylic group concentration 0.00011 equivalents / g) Inorganic filler B'-2: Solvent dispersion of silica surface-treated with the methacrylate silane prepared above (particle size 12 nm, (meth)acrylic group concentration 0.00005 equivalents / g) Inorganic filler B'-3: Solvent dispersion of silica surface-treated with the methacrylate silane prepared above (particle size 12 nm, (meth)acrylic group concentration 0.00050 equivalents / g) Thermosetting resin C-1: Phenol novolac type epoxy resin RE-306-SA9 (solid content epoxy group equivalent 180) manufactured by Nippon Kayaku Co., Ltd. Thermosetting resin C-2: phenol novolac type epoxy resin EPICLON® N770-75EA (solid content epoxy group equivalent 190), manufactured by DIC Corporation. Thermosetting resin C-3: Biphenyl-type epoxy resin YX4000 manufactured by Mitsubishi Chemical Corporation (solid content epoxy group equivalent 190) Photopolymerization initiator D-1: Omnirad 379 (2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)-butan-1-one) manufactured by IGM Resins BV Photopolymerization initiator D-2: IRGACURE® OXE02 manufactured by BASF Japan Ltd. Photopolymerizable monomer E-1: Dipentaerythritol hexaacrylate (DPHA) Coloring agent F-1: Firstgen Blue 5380 Coloring agent F-2: Yellow S1515 / AGR Thermosetting catalyst G-1: Dicyandiamide (DICY) Thermosetting catalyst G-2: Melamine Additive H-1: Oil compound type defoaming agent KS-66 manufactured by Shin-Etsu Chemical Co., Ltd. Organic Solvent I-1: Juksol CA (carbitol acetate) manufactured by Dow Chemical Japan Ltd.

[0101] [Measurement of (meth)acrylic group concentration in carboxyl group-containing resins and photopolymerizable monomers] The (meth)acrylic group concentrations of each carboxyl group-containing resin and photopolymerizable monomer described above were measured according to the following procedure. First, 0.1 g of each carboxyl group-containing resin and photopolymerizable monomer sample was accurately weighed and dissolved in 10 ml of morpholine using ultrasound. 7 ml of a 1:1 acetic acid / water mixture was added, and the mixture was heated in an oil bath at 98°C for 30 minutes to react with the morpholine. Next, the reaction solution was left at room temperature, and 25 ml of methyl cellosolve and 20 ml of acetic anhydride were added to react with the unreacted morpholine. The solution was then left at room temperature to prepare the solution for measurement. The (meth)acrylic group concentration was calculated by titrating the obtained solution with a 0.1 N perchloric acid solution.

[0102] [Table 1-1] TIFF0007898605000003.tif213170

[0103] The "total solid content of the curable resin composition", the "(meth)acrylic group concentration with respect to the total solid content of the curable resin composition", the "proportion of the solid content (meth)acrylic group concentration derived from the (E) polymerizable monomer", the "proportion of the solid content (meth)acrylic group concentration derived from the (A) carboxyl group-containing resin", and the "proportion of the solid content (meth)acrylic group concentration derived from the (B') acrylic group-containing surface-treated inorganic filler" of each obtained curable resin composition are shown in Table 1, respectively.

[0104] [Evaluation of photocurability (sensitivity)] The photocurability (sensitivity) of each curable resin composition was evaluated according to the following procedure. First, each curable resin composition was applied to the entire surface of a copper-plated substrate (copper-plated on an FR-4 copper-clad laminate substrate with a size of 15 cm × 9.5 cm, a thickness of 0.8 mm, and a circuit thickness of 18 μm, surface-treated (CZ8101B chemical solution, CZ roughening treatment at an etching rate of 1.0 μm)) by the screen printing method so that the film thickness after drying was 15 μm, and dried in a hot air circulation dryer at 80 °C for 20 minutes. Next, exposure was performed using a DI exposure machine (exposure device Mms-60 manufactured by Oak Co., Ltd.) through an Eastman Kodak Kodak Photographics Step Tablet No. 2. Next, using a 1 wt% aqueous sodium carbonate solution, spray pressure 2 kg / cm 2 and development was carried out for 90 seconds. From the exposure amount at which the remaining number of steps after development was 10 steps, the photocurability (sensitivity) of each curable resin composition was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. ◎: The exposure amount at which the remaining number of steps after development is 10 steps is less than 150 mJ / cm 2 . ○: The exposure amount at which the remaining number of steps after development is 10 steps is 150 mJ / cm or more 2 and less than 300 mJ / cm 2 . ×: The exposure amount at which the remaining number of steps after development is 10 steps is 300 mJ / cm or more 2 .

[0105] [Resolution evaluation] The resolution of the cured products of each curable resin composition was evaluated according to the following procedure. First, a copper-plated substrate (FR-4 copper-clad laminate, 15cm x 9.5cm, 0.8mm thick, circuit thickness 18μm, copper-plated) that had undergone surface treatment (CZ8101B chemical solution, CZ roughening treatment at an etching rate of 1.0μm) was coated with each curable resin composition by screen printing so that the film thickness after drying would be 15μm. The substrate was then dried in a hot air circulating drying oven at 80°C for 20 minutes. Next, exposure was performed using a DI exposure machine (Mms-60 exposure unit manufactured by Oak Co., Ltd.) via an Eastman Kodak Kodak Photographic Step Tablet No. 2, with exposure levels that resulted in 10 remaining stages, using various aperture patterns (apertures of Φ30~150μm (at Φ10μm intervals) formed at 200μm intervals). Finally, a 1wt% sodium carbonate aqueous solution was sprayed at a spray pressure of 2kg / cm². 2 Development was performed for 90 seconds. Then, the film was subjected to an integrated exposure of 1000 mJ / cm² in a UV conveyor oven. 2 A substrate for resolution evaluation was obtained by irradiating with ultraviolet light under the specified conditions and heating at 150°C for 60 minutes. The aperture diameter of the obtained resolution evaluation substrate was observed at 500x magnification using an electron microscope JSM-6610LV manufactured by JEOL Ltd., and the resolution of the cured material was evaluated according to the following evaluation criteria based on the minimum aperture diameter size at which halation and undercuts did not occur. ◎...The minimum aperture diameter at which halation and undercuts do not occur is less than 60 μm. ○...The minimum aperture diameter at which halation and undercut do not occur is 60 μm or more and less than 90 μm. △...The minimum aperture diameter at which halation and undercut do not occur is 90 μm or more and less than 120 μm. ×...The minimum aperture diameter at which halation and undercuts do not occur is 120 μm or larger.

[0106] [Evaluation of the fracture strength of hardened material] The tensile strength of the cured products of each curable resin composition was evaluated according to the following procedure. First, each curable resin composition was applied to the entire surface of a 18 μm thick glossy copper foil cut to 150 mm x 100 mm using a screen printing method, so that the film thickness after drying would be 30 μm. It was then dried in a hot air circulating drying oven at 80°C for 20 minutes. Next, strip patterns measuring 10 mm wide x 80 mm long were exposed using a DI exposure machine (Mms-60 exposure device manufactured by Oak Co., Ltd.) with an exposure dose equivalent to 10 stops on an Eastman Kodak Kodak Photographic Step Tablet No. 2. Then, a 1 wt% sodium carbonate aqueous solution was sprayed at a spray pressure of 2 kg / cm². 2 Development was performed for 90 seconds. Then, the film was subjected to an integrated exposure of 1000 mJ / cm² in a UV conveyor oven. 2 Under these conditions, the material was irradiated with ultraviolet light and heated at 150°C for 60 minutes to obtain a cured product. The copper foil was peeled off the obtained cured product to obtain a sample for evaluating the breaking strength. A tensile test was performed on the sample for evaluating the breaking strength at a tensile speed of 1 mm / min with a grip distance of 40 mm, and the maximum point stress was measured. The measurement was performed using a tensile testing machine AGS-G100N manufactured by Shimadzu Corporation, and the maximum point stress was evaluated. The breaking strength of the evaluation sample was evaluated according to the evaluation criteria below. ◎...The maximum point stress is 80 MPa or higher. ○...The maximum point stress is between 60 MPa and 80 MPa. ×...The maximum point stress is less than 60 MPa.

[0107] [Evaluation of solder heat resistance] The solder heat resistance of the cured products of each curable resin composition was evaluated according to the following procedure. First, each curable resin composition was applied to the entire surface of an FR-4 copper-clad laminate substrate measuring 15 cm in length, 9.5 cm in width, 0.8 mm in thickness, and 18 μm in circuit thickness, using a screen printing method, so that the film thickness on the copper after drying would be 15 μm. It was then dried in a hot air circulating drying oven at 80°C for 20 minutes. Next, exposure was performed using a DI exposure machine (Mms-60 exposure unit manufactured by Oak Co., Ltd.) with an exposure dose equivalent to 10 steps on an Eastman Kodak Kodak Photographic Step Tablet No. 2. Finally, a 1 wt% sodium carbonate aqueous solution was sprayed at a spray pressure of 2 kg / cm². 2Development was performed for 90 seconds. Then, the film was subjected to an integrated exposure of 1000 mJ / cm² in a UV conveyor oven. 2 Under these conditions, the substrates were irradiated with ultraviolet light and heated at 150°C for 60 minutes to obtain a substrate for evaluating solder heat resistance. After applying rosin-based flux to the obtained substrates for evaluating solder heat resistance, they were immersed for 10 seconds in a solder bath pre-set to 260°C. Next, the flux was washed off with ethanol, and the blistering and peeling of the cured material were observed visually, and the evaluation was performed according to the following criteria. ◎: No peeling of the hardened material was observed even after repeating immersion for 10 seconds five or more times. ○: Repeat immersion for 10 seconds 3 to 5 times, and peeling of the hardened material occurs. ×: If the hardened material swells or peels off after immersion for 10 seconds three times or less.

[0108] [Evaluation of dryness to the touch] The touch-drying properties of each curable resin composition were evaluated according to the following procedure. First, each curable resin composition was applied to the entire surface of a substrate (15cm x 9.5cm, 1.6mm thick, FR-4 copper-clad laminate) having a circuit pattern with a copper thickness of 18μm, using a screen printing method, so that the copper film thickness after drying was 15μm. The resin layer was then formed by drying in a hot air circulating drying oven at 80°C for 20 minutes. The surface of the resin layer was then touched with an index finger with enough force to make direct contact with the entire fingertip for 1 minute to check for stickiness. Touch-dryness was evaluated according to the following criteria. ◎: Not sticky at all. ○: Slightly sticky. ×: It is sticky.

[0109] As shown in Table 1, the curable resin compositions in Examples 1 to 13, which contain a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, and in which the concentration of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is adjusted to 0.00070 to 0.00170 equivalents / g, exhibit excellent photocurability (sensitivity) and resolution. On the other hand, the curable resin compositions in Comparative Examples 1 to 2, which contain a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, but in which the concentration of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is not adjusted to 0.00070 to 0.00170 equivalents / g, exhibit poor photocurability (sensitivity) and resolution.

[0110] Furthermore, it can be seen that each of the curable resin compositions in Examples 1 to 13 exhibits excellent photocurability (sensitivity) and resolution, as well as excellent touch-drying properties, tensile strength of the cured product, and solder heat resistance.

Claims

1. A curable resin composition comprising a carboxyl group-containing resin, an inorganic filler, a thermosetting resin, a photopolymerization initiator, and a photopolymerizable monomer, The concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00070 to 0.00170 equivalents / g. A curable resin composition characterized in that 30 to 55% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer.

2. The inorganic filler includes an inorganic filler having (meth)acrylic groups on its surface, Of the concentrations of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition, 30-60% are derived from the carboxyl group-containing resin, 5-30% are derived from the inorganic filler having the (meth)acrylic group, 30-55% are derived from the aforementioned photopolymerizable monomers. The curable resin composition according to claim 1.

3. The curable resin composition according to claim 1, wherein the concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00070 to 0.00140 equivalents / g.

4. The curable resin composition according to claim 1, wherein 40 to 55% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer.

5. The curable resin composition according to claim 1, wherein the concentration of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition is 0.00080 to 0.00110 equivalents / g.

6. The curable resin composition according to claim 1, wherein 45 to 55% of the total amount of (meth)acrylic groups relative to the total mass of solids in the curable resin composition are (meth)acrylic groups derived from the photopolymerizable monomer.

7. A cured product obtained by curing the curable resin composition described in claim 1.

8. A printed circuit board comprising the cured material described in claim 7.

9. A method for manufacturing a printed circuit board having an insulating layer, comprising the step of forming the insulating layer by curing the curable resin composition described in claim 1.

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