Curable resin compositions, dry films, cured products, and electronic components

Abstract

The present invention provides: a curable resin composition which exhibits excellent resolution and higher insulation reliability, while having excellent embeddability into a circuit; a dry film; a cured product; and an electronic component which comprises the curable resin composition, the dry film or the cured product. A curable resin composition which contains (A) a carboxyl group-containing resin, (B) a photopolymerization initiator, (C) a thermosetting resin and (D) silica, and which is characterized in that: the blending amount of the silica (D) is 0 to 60% by mass relative to the total solid content of the curable resin composition; the silica (D) contains (D-1) nanosilica; the nanosilica (D-1) has an average secondary particle diameter of 200 nm or less; and the degree of association of the nanosilica (D-1) is 2.3 or less.

Description

[Technical Field]

[0001] The present invention relates to curable resin compositions, dry films, cured products, and electronic components containing them. [Background technology]

[0002] In recent years, as there has been a demand for miniaturization and increased performance of electronic components, semiconductor chips mounted on these components have also become more densely packed and feature-rich. Consequently, printed circuit boards on which these semiconductor chips are mounted are also required to be smaller and denser. To manufacture highly integrated printed circuit boards, the development of insulating materials (such as solder resists and insulating films) with high resolution and reliability is progressing.

[0003] For example, Patent Document 1 discloses that a photosensitive resin composition containing a resin having ethylenically unsaturated groups and carboxyl groups, a photopolymerizable monomer having ethylenically unsaturated groups, an epoxy resin, and silica with an average particle size of less than 50 nm can provide an alkali-developable photosensitive film that can form a fine aperture pattern without impairing developability, has excellent HAST resistance between fine wiring, and possesses high heat resistance. Patent Document 1 also discloses that, as an evaluation of HAST resistance indicating insulation reliability, the photosensitive resin composition was used to evaluate a comb-shaped electrode with a line / space of 50 μm / 50 μm on the circuit. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2012-242592 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0005] However, although the photosensitive resin composition disclosed in Patent Document 1 has the above-mentioned excellent characteristics, it is difficult to embed it between narrow wirings (poor embedding ability in circuits), which may cause insulation failure in printed circuit boards. Furthermore, with the increasing density of printed circuit boards in recent years, higher insulation reliability is required, so the HAST resistance evaluation using comb-shaped electrodes with a line / space of 50 μm / 50 μm on the circuit disclosed in Patent Document 1 may be insufficient, and there is a need for superior HAST resistance under conditions with narrower line / space.

[0006] Therefore, the object of the present invention is to provide a curable resin composition and dry film, as well as cured products thereof, and electronic components using them, which have excellent resolution, higher insulation reliability, and excellent embedding properties in circuits. [Means for solving the problem]

[0007] As a result of diligent research toward achieving the above objective, the inventors have found that a curable resin composition containing silica having a specific degree of association and average secondary particle size can solve the above problem, and have completed the present invention. That is, the present invention is as follows.

[0008] The present invention (1) is, A curable resin composition comprising (A) a carboxyl group-containing resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) silica, The amount of silica (D) blended is 10 to 60% by mass relative to the total solid content of the curable resin composition. The (D) silica mentioned above includes (D-1) nanosilica, The average secondary particle size of the (D-1) nanosilica is 200 nm or less. The curable resin composition is characterized in that the degree of association of the (D-1) nanosilica is 2.3 or less. The present invention (2) is, The (D) silica further comprises (D-2) other silica, which is different from the (D-1) nanosilica and has an average secondary particle diameter of more than 200 nm, and is a curable resin composition of the invention (1). The present invention (3) is The curable resin composition of invention (2) is characterized in that the average secondary particle size of the other silica (D-2) is 400 nm to 1600 nm. The present invention (4) is, The curable resin composition according to any of the above inventions (1) to (3) is characterized in that the amount of (D-1) nanosilica blended is 50% by mass or more relative to the total amount of (D) silica blended. The present invention (5) is, The curable resin composition is a curable resin composition according to any of the inventions (1) to (4) above, further characterized by containing (E) rubber particles. The present invention (6) is, This dry film is characterized by having a resin layer obtained by applying and drying any of the curable resin compositions of invention (1) to (5) described above onto a film. The present invention (7) is, A cured product characterized by being obtained by curing a curable resin composition according to any of the above inventions (1) to (5), or the resin layer of a dry film according to invention (5). The present invention (8) is, This is an electronic component characterized by having the cured product of the above invention (7). [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a curable resin composition and dry film, as well as cured products thereof, that have excellent resolution, higher insulation reliability, and excellent embedding properties in circuits, and electronic components using the same. [Modes for carrying out the invention]

[0010] The curable resin composition of the present invention will be described below, but the present invention is not limited to the following.

[0011] When isomers exist in the described compounds, unless otherwise specified, all possible isomers can be used in the present invention.

[0012] In this specification, "resin composition" may be used in the meaning of "curable resin composition".

[0013] In this specification, when "(meth)acryl" is described, it shall include both "methacryl" and "acryl".

[0014] In this specification, when the upper limit value and the lower limit value of a numerical range are separately described, all combinations of each lower limit value and each upper limit value within a non - contradictory range are substantially described.

[0015] 1. Curable resin composition The curable resin composition of the present invention contains (A) a carboxyl - group - containing resin, (B) a photoinitiator, (C) a thermosetting resin, and (D) silica. Further, the curable resin composition of the present invention can contain (E) rubber particles. Furthermore, the curable resin composition of the present invention can contain other components.

[0016] Hereinafter, each component of the curable resin composition will be described. 1 - 1. (A) Carboxyl - group - containing resin The curable resin composition of the present invention contains a carboxyl - group - containing resin, and thus has excellent adhesion to the substrate and excellent developability. The carboxyl - group - containing resin may be a carboxyl - group - containing photosensitive resin having an ethylenically unsaturated group or a carboxyl - group - containing resin having no ethylenically unsaturated group. Among them, a carboxyl - group - containing resin having an ethylenically unsaturated group is preferable because of its excellent photocurability and developability resistance.

[0017] Specific examples of the carboxyl - group - containing resin may include the following compounds (either oligomers or polymers).

[0018] (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.

[0019] (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, phenolic hydroxyl groups, and compounds having alcoholic hydroxyl groups.

[0020] (3) A urethane resin containing terminal carboxyl groups, obtained by reacting an acid anhydride at the ends of a urethane resin by polyaddition reaction of a diisocyanate compound such as aliphatic diisocyanate, branched aliphatic diisocyanate, alicyclic diisocyanate, or aromatic diisocyanate with a diol compound such as a polycarbonate polyol, polyether polyol, polyester polyol, polyolefin polyol, acrylic polyol, bisphenol A alkylene oxide adduct diol, a phenolic hydroxyl group, or a compound having an alcoholic hydroxyl group.

[0021] (4) A carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanate with (meth)acrylate or partially acid anhydride modified products thereof of difunctional epoxy resins 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, and biphenol type epoxy resin, carboxyl group-containing dialcohol compounds, and diol compounds.

[0022] (5) A carboxyl group-containing 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, during the synthesis of the resin described in (2) or (4) above, and then (meth)acrylicating the terminal (meth) resin.

[0023] (6) A carboxyl group-containing urethane resin obtained by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in its molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, to the synthesis of the resin of (2) or (4) above, and then (meth)acrylicating the terminals.

[0024] (7) A carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin with (meth)acrylic acid and adding dibasic acid anhydrides such as phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride to the hydroxyl groups present in the side chains.

[0025] (8) A carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

[0026] (9) A carboxyl group-containing polyester resin obtained by reacting a polyfunctional oxetane resin with a dicarboxylic acid and adding a dibasic acid anhydride to the resulting primary hydroxyl group.

[0027] (10) A carboxyl group-containing resin obtained by reacting a reaction product obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

[0028] (11) A carboxyl group-containing 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.

[0029] (12) A carboxyl group-containing 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 reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride.

[0030] (13) A carboxyl group-containing resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, to the carboxyl group-containing resin described in (1) to (12) above.

[0031] These carboxyl group-containing resins can be used individually or in combination.

[0032] It is preferable that the carboxyl group-containing resin contains at least one of the carboxyl group-containing resins described in (7), (8), (10), (11), and (13), and it is more preferable to include the carboxyl group-containing resin described in (7) and (10) from the viewpoint of further improving insulation reliability.

[0033] The acid value of the carboxyl group-containing resin is not particularly limited, but is, for example, 40 to 200 mg KOH / g, preferably 45 to 120 mg KOH / g. When the acid value of the carboxyl group-containing resin is within this range, alkaline development after exposure becomes easier and resolution is improved.

[0034] 1-2. (B) Photopolymerization initiator The photopolymerization initiator according to the present invention is not particularly limited, and any photopolymerization initiator known as a photopolymerization initiator or photoradical generator can be used.

[0035] 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, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, among other bisacylphosphine oxides; Monoacyl phosphine oxides such as 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphate methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphate isopropyl ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; Hydroxyacetophenones such as 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, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; Benzoin compounds such as benzoin, benzyl benzoin, 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; Acetophenones such as 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-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; Anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; Ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; Benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethylbenzoate, and p-dimethylbenzoate ethyl ester; Oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], etanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime); Titanocenes 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; Examples include phenyl disulfide 2-nitrofluorene, butyroine, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide. These can be used individually or in combination.

[0036] The amount of photopolymerization initiator is not particularly limited, but for example, 0.5 to 20 parts by mass in terms of solid content per 100 parts by mass of carboxyl group-containing resin is preferred. When the amount of photopolymerization initiator is within this range, a curable resin composition can be obtained that has excellent surface curability, is less prone to halation, and has good resolution.

[0037] 1-3.(C) Thermosetting resin The (C) thermosetting resin according to the present invention is not particularly limited, and for example, isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy resins, oxetane compounds, episulfide resins, etc. can be used. These can be used individually or in combination. Of these, epoxy resins are preferably used.

[0038] Examples of epoxy resins include bisphenol A type epoxy resins; brominated epoxy resins; novolac type epoxy resins; bisphenol F type epoxy resins; hydrogenated bisphenol A type epoxy resins; biphenyl type epoxy resins; glycidylamine type epoxy resins; hydantoin type epoxy resins; alicyclic epoxy resins; triphenylmethane type epoxy resins; trihydroxyphenylmethane type epoxy resins; bixylenol type or biphenol type epoxy resins, or mixtures thereof; bisphenol S type epoxy resins; bisphenol A novolac type epoxy resins; tetraphenyloleethane type epoxy resins; heterocyclic epoxy resins; diglycidyl phthalate resins; tetraglycidyl xylenoylethane resins; naphthalene group-containing epoxy resins; epoxy resins having a dicyclopentadiene skeleton; epoxy resins having a silsesquioxane skeleton; glycidyl (meth)acrylate copolymer epoxy resins; copolymer epoxy resins of cyclohexylmaleimide and glycidyl (meth)acrylate; epoxy-modified polybutadiene rubber derivatives; CTBN-modified epoxy resins, etc. These can be used individually or in combination.

[0039] Of these, epoxy resins having a dicyclopentadiene skeleton are preferred because they have an alicyclic skeleton, thus improving the resolution of the curable resin composition of the present invention. Furthermore, biphenyl-type epoxy resins and novolac-type epoxy resins are preferred because they have an aromatic ring skeleton, thus improving the heat resistance of the curable resin composition and the cured dry film of the present invention.

[0040] The amount of epoxy resin to be blended is not particularly limited, but for example, it is preferable that the amount of epoxy groups of the blended epoxy resin be 0.8 to 2.5 mol per 1.0 mol of carboxyl groups contained in (A) carboxyl group-containing resin, and more preferably 1.0 to 2.0 mol. By using an amount of 0.8 mol or more, it is possible to prevent the residue of carboxyl groups in the cured film and obtain good heat resistance, alkali resistance, electrical insulation, etc. Furthermore, by using an amount of 2.5 mol or less, it is possible to prevent low molecular weight epoxy resin from remaining in the dried coating film and ensure good strength of the cured film, etc.

[0041] 1-4. (D) Silica The (D) silica in the present invention is not particularly limited, and examples include spherical silica, fine silicon oxide, amorphous silica, crystalline silica, fused silica, etc. These can be used individually or in combination. The silica can preferably be that which is disclosed in International Publication No. 2020 / 179559 or that is produced by the manufacturing method disclosed in Japanese Patent Application Publication No. 2018-168031.

[0042] (D) Silica includes (D-1) nanosilica. In this specification, nanosilica refers to silica with an average secondary particle diameter of 200 nm or less. Furthermore, (D-1) nanosilica has a degree of association of 2.3 or less. By using such silica, the effects of the present invention can be obtained. Although the mechanism by which these effects can be obtained is not clear, it is presumed that the fluidity of the curable resin composition is improved, resulting in excellent embedding properties in circuits; the compatibility between silica and resin components in the curable resin composition is excellent, resulting in high insulation reliability; and light scattering during exposure is suppressed, resulting in excellent resolution. The degree of silica association is calculated according to (Equation 1). (Formula 1) Degree of association of silica = Average secondary particle diameter of silica / Average primary particle diameter of silica The average primary particle diameter refers to the average particle diameter of individual, non-aggregated silica particles. The average primary particle diameter of silica is calculated by measuring the BET specific surface area of ​​the silica (particle aggregate) and assuming a true specific gravity of 2.2, according to formula (2) below. (Formula 2) Average primary particle diameter = 6 / (True specific gravity × BET specific surface area measurement)

[0043] The BET specific surface area of ​​silica can be measured using the carrier gas method with nitrogen gas in accordance with JIS Z 8830:2013. The evaluation device used is the QUANTACHROME AUTOSORB-1 (product name), and the BET specific surface area is measured by analyzing the obtained isothermal adsorption curves using the multi-point method.

[0044] Since moisture adsorbed on the sample surface and within its structure is thought to affect nitrogen adsorption capacity, a pretreatment to remove moisture by heating is performed before measuring the BET specific surface area. Specifically, as a pretreatment, the silica for measurement is pre-dried on a hot plate, and then heat-treated at 800°C for 1 hour to prepare the sample for measurement. After this pretreatment, the BET specific surface area is measured at an evaluation temperature of 77K.

[0045] The average secondary particle diameter refers to the average particle diameter of aggregates of primary particles. Furthermore, in this specification, the average secondary particle diameter is the volume-average particle diameter (D50 volume%) measured by dynamic light scattering using a laser diffraction analyzer for silica aggregates. That is, if primary particles are present in the silica aggregate, the average secondary particle diameter includes the particle diameter of the primary particles.

[0046] Specifically, the average secondary particle size of silica is measured using the following method. • Particle size distribution meter: Microtrac MT3300EX, manufactured by Nikkiso Co., Ltd. • Circulation system: ASVR manufactured by Nikkiso Co., Ltd. First, enter the measurement conditions using the following steps: Launch the software included with Microtrac ("Particle Size Distribution Measurement"), proceed from the SET UP screen, and set the time from the measurement condition settings options. Set the Setzero time to 30 sec., the measurement to 30 sec., and the number of measurements to 2. Next, enter the analysis conditions. In the analysis information, set the particle refractive index to 1.81 (fixed value: average value of the refractive index of all inorganic substances), and in the particle characteristics, set the permeability to permeable and the shape to non-spherical. Also, in the solvent information, select PMA (propylene glycol monomethyl ether acetate) and set the solvent refractive index to 1.4. Next, enter the scale settings. In the particle size range, set the minimum particle size to 0.021 μm and the maximum particle size to 704 μm. Next, enter the sampling system. Set the number of ASVR washes to 4, the flow rate to 50%, the ultrasonic output to 40 W, and the ultrasonic time to 300 sec. After entering all the measurement conditions, press Save in the measurement condition settings to close. Next, prepare the sample using the following procedure. Use the raw silica before it is incorporated into the curable resin composition as the sample. If silica is incorporated as a powder, use that powder as the sample; if silica is dispersed in a solvent, use the solvent dispersion as the sample. Weigh 0.3 g of the sample into a screw-top bottle, and using a dropper, gradually add 30 g of propylene glycol monomethyl ether acetate. Disperse the sample by shaking the screw-top bottle to prepare the prepared sample. Do not perform external dispersion or pre-dispersion of the prepared sample. Next, measure the prepared sample. Click on particle size distribution measurement in the software included with the Microtrac to open the sample loading screen. Using a dropper, drop a few drops of the prepared sample into the sample inlet of the main unit. When a red indicator bar appears on the sample loading screen, drop the prepared sample into the sample inlet until it falls within the range from red to green. Once it falls within the green range, press the measurement button to start the measurement. The entire process from sample preparation to measurement of the prepared sample should be completed within 5 minutes. The value of the cumulative volume average diameter at 50% displayed as the measurement result is taken as the average particle diameter D50.

[0047] Here, the upper limit of the average primary particle diameter of (D-1) nanosilica is 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less, and even more preferably 90 nm or less. The lower limit of the average primary particle diameter of (D-1) nanosilica is 5 nm or more, preferably 10 nm or more, and more preferably 12 nm or more.

[0048] (D-1) The upper limit of the average secondary particle diameter of nanosilica is 200 nm or less, preferably 180 nm or less, and more preferably 160 nm or less. (D-1) The lower limit of the average secondary particle diameter of nanosilica is 10 nm or more, preferably 15 nm or more, and more preferably 19 nm or more.

[0049] The degree of association of (D-1) nanosilica is 2.3 or less, preferably 2.0 or less. Furthermore, the degree of association of (D-1) nanosilica is preferably 1.2 or more, and more preferably 1.4 or more. When the degree of association is 1.2 or more, the fluidity of the curable resin composition is improved, resulting in superior circuit embedding properties.

[0050] The degree of silica association can be adjusted, for example, by controlling the concentration of the alkaline catalyst, the temperature of the reaction solution, etc., within a predetermined addition rate range for adding liquid (B) to liquid (A) in the manufacturing method disclosed in the aforementioned Japanese Patent Publication No. 2018-168031 (see paragraph 0049 of Japanese Patent Publication No. 2018-168031). In this invention, the average primary particle diameter, average secondary particle diameter, and degree of association represent the values ​​in the solvent dispersion or powder state, which is the state before being incorporated into the curable resin composition, as is clear from the measurement method described above.

[0051] (D) Silica may further contain silica different from (D-1) nanosilica (hereinafter referred to as (D-2) other silica). (D-2) other silica refers to silica with an average secondary particle diameter of more than 200 nm. The average secondary particle diameter of (D-2) other silica is preferably 400 to 1600 nm. When (D-2) other silica is blended into a curable resin composition compared to (D-1) nanosilica, the curable resin composition exhibits superior coating properties. Furthermore, by using (D-1) nanosilica and (D-2) other silica in combination, properties such as resolution and crack resistance can be maintained while reducing the amount of (D-1) nanosilica blended. Therefore, by including (D-2) other silica, a curable resin composition of the present invention with excellent coating properties can be obtained.

[0052] (D) The amount of silica added is 10 to 60% by mass relative to the total solid content of the curable resin composition of the present invention, more preferably 10 to 50% by mass, even more preferably 10 to 35% by mass, even more preferably 15 to 35% by mass, particularly preferably 15 to 30% by mass, and most preferably 20 to 30% by mass. When the amount of silica added is within this range, a curable resin composition can be obtained that is superior in resolution and circuit embedding ability, and further superior in the insulation reliability, crack resistance, and heat resistance of the cured product. Note that the amount of silica added is rounded to the first decimal place.

[0053] The amount of (D-1) nanosilica can be 100% by mass relative to the total amount of (D) silica. Alternatively, the amount of (D-1) nanosilica can be 50% by mass or more and less than 100% by mass relative to the total amount of (D) silica, with 90% by mass or more and less than 100% by mass being more preferable. When the amount of (D-1) nanosilica is 100% by mass, a curable resin composition with superior resolution can be obtained. On the other hand, by setting the amount of (D-1) nanosilica to 50% by mass or more and less than 100% by mass, the coatability of the curable resin composition of the present invention can be improved while maintaining properties such as resolution and crack resistance.

[0054] (D-2) The amount of other silica can be 50% by mass or less, and more preferably 10% by mass or less, relative to the total amount of silica in (D).

[0055] 1-5. (E) Rubber particles The (E) rubber particles in the present invention are not particularly limited, and for example, silicone elastomers, butadiene elastomers, styrene elastomers, acrylic elastomers, polyolefin elastomers, silicone / acrylic composite elastomers, etc. can be used. These can be used individually or in combination. Of these, butadiene elastomers and styrene elastomers are preferably used.

[0056] (E) The average secondary particle diameter of the rubber particles is not particularly limited, but is preferably 2 μm or less, and more preferably 0.01 μm to 1 μm. When the average secondary particle diameter of the rubber particles is within this range, a curable resin composition with superior crack resistance can be obtained.

[0057] (E) The amount of rubber particles added is 0 to 32% by mass, preferably 0.1 to 10% by mass, and more preferably 0.5 to 7% by mass, relative to the total solid content of the curable resin composition of the present invention. (E) When the amount of rubber particles added is within this range, a curable resin composition with even better circuit embedding properties and crack resistance after curing can be obtained.

[0058] 1-6. Other ingredients The curable resin composition of the present invention may contain other components known and commonly used in the field of electronic materials. Examples of other components include photocurable compounds, thermosetting compounds, colorants, thermosetting catalysts, organic solvents, thermal polymerization inhibitors, ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, anti-aging agents, antioxidants, antibacterial and antifungal agents, defoaming agents, leveling agents, thickeners, adhesion promoters, thixotropic agents, photoinitiator aids, sensitizers, photobase generators, thermoplastic resins, elastomers, organic fillers, release agents, surface treatment agents, dispersants, dispersion aids, surface modifiers, stabilizers, phosphors, and the like. These can be used individually or in combination.

[0059] 2. Dry film The effective resin composition of the present invention can be applied to a film (hereinafter also referred to as the "first film") and then dried to produce a dry film.

[0060] The dry film of the present invention can be obtained by diluting the curable resin composition of the present invention with an organic solvent to adjust it to an appropriate viscosity, applying it 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 drying it at a temperature of 50 to 130°C for 1 to 30 minutes. There are no particular restrictions on the coated film thickness, but generally, the film thickness after drying can be appropriately set in the range of 3 to 100 μm, preferably 5 to 40 μm.

[0061] As the first film, a plastic film can be suitably used, and it is preferable to use a plastic film such as a polyester film like polyethylene terephthalate, a polyimide film, a polyamide-imide film, a polypropylene film, or a polystyrene film. The thickness of the first film is not particularly limited, but it can generally be in the range of 10 to 150 μm.

[0062] After applying and drying the curable resin composition of the present invention onto the first film to obtain a resin layer on the first film, a peelable film (hereinafter also referred to as the "second film") may be laminated on the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. Examples of peelable second films include polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc., and it is sufficient that the adhesive force between the resin layer and the second film is less than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0063] The drying process performed after applying the curable resin composition of the present invention onto the first film can be carried out using a hot air circulating drying oven, an IR oven, a hot plate, a convection oven, or the like.

[0064] 3.Cured product The cured product of the present invention is obtained by curing the resin layer of the curable resin composition or dry film described above.

[0065] The method for obtaining a cured product from a curable resin composition or dry film is not particularly limited and can be appropriately modified depending on the composition of the curable resin composition.

[0066] As a method for curing the curable resin composition of the present invention, for example, the curable resin composition of the present invention is adjusted to a viscosity suitable for the application method using an organic solvent, and applied to a substrate by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating. After that, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60 to 100°C to form a tack-free resin layer on the substrate.

[0067] One method for forming a cured product using the dry film of the present invention is to laminate (form) the resin layer on the substrate by laminating the dry film onto the substrate using a laminator or the like so that the resin layer of the dry film is in contact with the substrate, and then peeling off the first film.

[0068] A cured product can be obtained by applying an exposure treatment to the resin layer. Examples of these exposure processes include a method in which a resin layer is formed on a circuit board, and then selectively exposed to active energy rays through a photomask on which a predetermined pattern is formed. More specifically, the cured product of the present invention can be obtained as follows. The resin layer on the substrate, prepared by the method described above, is selectively exposed to active energy rays through a photomask with a predetermined pattern, and the unexposed areas are developed with a dilute alkaline aqueous solution (for example, a 0.3-3% by mass sodium carbonate aqueous solution) to form the pattern on the resin layer. Furthermore, the cured product of the present invention can be obtained by irradiating the resin layer with active energy rays and then heat-curing it (for example, at 100-220°C for 30-120 minutes), or by irradiating it with active energy rays after heat curing, or by performing final finishing curing by heat curing alone.

[0069] The exposure machine used for active energy ray irradiation can be any device that irradiates ultraviolet light in the range of 350 to 450 nm, equipped with a high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, mercury short-arc lamp, etc. Furthermore, a direct writing device (for example, a laser direct imaging device that directly draws 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 writing device can have a maximum wavelength in the range of 350 to 450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but is generally 10 to 1000 mJ / cm². 2 Preferably 20-800 mJ / cm² 2 It can be within the range of

[0070] Development methods include, for example, the dipping method, shower method, spray method, and brush method. As for the developing solution, alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used.

[0071] 4. Electronic components The curable resin composition and dry film of the present invention can be applied, dried, or laminated at predetermined positions on a substrate to form a cured product, which can then be used to form a circuit board or other electronic component such as a printed wiring board.

[0072] The curable resin composition and dry film of the present invention are suitably used to form a cured film on a circuit board, more suitably used to form a permanent coating, and even more suitably used to form a solder resist, an interlayer insulating layer, or a coverlay. They are also suitable for forming permanent coatings (especially solder resists) for printed circuit boards with fine wiring patterns requiring high reliability, such as package substrates, and particularly for FC-BGAs. For example, they can be suitably used even with fine pitches where L / S is 10 μm / 10 μm or less, i.e., line width L is 10 μm or less and inter-line spacing is 10 μm or less. Furthermore, the curable resin composition and dry film of the present invention can be suitably used for printed circuit boards with wiring patterns even if the surface roughness of the circuit is low, such as high-frequency printed circuit boards. For example, they can be suitably used even if the surface roughness Ra is 0.5 μm or less, and particularly 0.3 μm or less. [Examples]

[0073] Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these.

[0074] <<<Preparation of curable resin composition>>> The preparation procedures for each curable resin composition (Compositions of Examples 1-8 and Comparative Examples 1-3) are described below.

[0075] <<Synthesis of carboxyl group-containing resins>> <Synthesis Example 1: Synthesis of Carboxyl Group-Containing Resin A1> In an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device, 119.4 parts by mass of novolac-type cresol resin (product name "Shonol CRG951", manufactured by Aica Kogyo Co., Ltd., OH equivalent: 119.4), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were introduced. The system was then heated and the temperature increased while stirring and purging with nitrogen. Next, 63.8 parts by mass of propylene oxide were gradually added dropwise to 125-132°C and 0-4.8 kg / cm³. 2 The reaction was carried out for 16 hours. After cooling to room temperature, 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac-type cresol resin with a solid content of 62.1% and a hydroxyl value of 182.2 mg KOH / g (307.9 g / eq.). This solution contained an average of 1.08 moles of propylene oxide added per equivalent of phenolic hydroxyl groups. 293.0 parts by mass of the propylene oxide reaction solution of the obtained novolac-type cresol resin, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and the mixture was reacted at 110°C for 12 hours while stirring. Of the water produced by the reaction, 12.6 parts by mass of water was distilled off as an azeotropic mixture with toluene. The mixture was then cooled to room temperature, and the resulting reaction solution was neutralized with 35.35 parts by mass of 15% aqueous sodium hydroxide solution, followed by washing with water. Subsequently, toluene was removed by distillation in an evaporator while substituting it with 118.1 parts by mass of diethylene glycol monoethyl ether acetate to obtain a novolac-type acrylate resin solution. Next, 332.5 parts by mass of the obtained novolac-type acrylate resin solution and 1.22 parts by mass of triphenylphosphine were introduced into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and while stirring, 60.8 parts by mass of tetrahydrophthalic anhydride were gradually added. The mixture was reacted at 95-101°C for 6 hours, and after cooling, it was removed. In this way, a solution of photosensitive carboxyl group-containing resin A1 with a solid content of 70.6% and an acid value of 87.7 mgKOH / g of the solid content was obtained.

[0076] <Synthesis Example 2: Synthesis of Carboxyl Group-Containing Resin A2> 650 parts by mass of diethylene glycol monoethyl ether acetate was charged with 1070 parts by mass of orthocresol novolac type epoxy resin (DIC Corporation, EPICLON N-695, softening point 95°C, epoxy equivalent 214, average number of functional groups 7.6) (number of glycidyl groups (total number of aromatic rings): 5.0 mol), 360 parts by mass (5.0 mol) of acrylic acid, and 1.5 parts by mass of hydroquinone. The mixture was heated to 100°C and stirred until uniformly dissolved. Next, 4.3 parts by mass of triphenylphosphine was charged, and the mixture was heated to 110°C and reacted for 2 hours. Then, an additional 1.6 parts by mass of triphenylphosphine was added, and the temperature was raised to 120°C and the reaction was carried out for a further 12 hours. 525 parts by mass of aromatic hydrocarbon (Sorvesso 150) and 608 parts by mass (4.0 mol) of tetrahydrophthalic anhydride were charged into the resulting reaction solution and the reaction was carried out at 110°C for 4 hours. Furthermore, 142.0 parts by mass (1.0 mole) of glycidyl methacrylate was added to the resulting reaction solution, and the reaction was carried out at 115°C for 4 hours to obtain a solution of carboxyl group-containing resin A2 with a solid content acid value of 77 mgKOH / g and a solid content of 65%.

[0077] <<Preparation of Silica Particle Organic Solvent Dispersion>> <Preparation Example 1: Preparation of Silica Particle Organic Solvent Dispersion D1> 500 g of silica particle aqueous dispersion (Fuso Chemical Co., Ltd., Quattron PL-3, silica concentration 20 wt%) was mixed with 400 g of γ-butyrolactone (GBL) and stirred. The dispersion medium of the silica sol was replaced with γ-butyrolactone by vacuum distillation using a rotary evaporator. This prepared silica particle organic solvent dispersion D1 (500 g) with an SiO2 concentration of 20 wt% and a water concentration of 1 wt% or less. The average primary particle diameter of the obtained silica nanoparticles was 35 nm, the average secondary particle diameter was 70 nm, and the degree of association was 2.0.

[0078] <Preparation Example 2: Preparation of Silica Particle Organic Solvent Dispersion D2> In a 5 L reaction vessel equipped with a stirrer and cooling function, a mixture of 2945 g methanol, 377.9 g pure water, and 218 g 29% by weight aqueous ammonia was added. While stirring at 300 rpm, a solution of 79 g methanol in which 309 g of tetramethoxysilane (TMOS) was dissolved was added at a rate of 11 mL / min while maintaining the reaction vessel's internal liquid temperature at 20°C to prepare a reaction solution and obtain a silica sol. 500 g of the prepared silica sol was mixed with 385 g of γ-butyrolactone (GBL) and stirred. The dispersion medium of the silica sol was replaced with γ-butyrolactone by vacuum distillation using a rotary evaporator. This prepared a silica particle organic solvent dispersion D2 (500 g) with an SiO2 concentration of 8% by weight and a water concentration of 1% by weight or less. The average primary particle diameter of the obtained silica nanoparticles was 83 nm, the average secondary particle diameter was 113 nm, and the degree of association was 1.4.

[0079] <Preparation Example 3: Preparation of Silica Particle Organic Solvent Dispersion D3> In a 5L reaction vessel equipped with a stirrer and cooling function, a mixture of 2945g methanol, 411.36g pure water, 108g 29% ammonia water, and 46.5g colloidal silica (silica concentration: 4% by weight, average secondary particle size: 8nm) was added. While stirring at 300 rpm, a solution of 79g methanol dissolved in 309g tetramethoxysilane (TMOS) was added at a rate of 0.74 mL / min while maintaining the reaction vessel's internal liquid temperature at 20°C to prepare a reaction solution and obtain a silica sol. 500g of the prepared silica sol was mixed with 385g of γ-butyrolactone (GBL) and stirred. The dispersion medium of the silica sol was replaced with γ-butyrolactone by vacuum distillation using a rotary evaporator. This prepared a silica particle organic solvent dispersion D3 (500g) with an SiO2 concentration of 8% by weight and a water concentration of 1% by weight or less. The obtained silica nanoparticles had an average primary particle diameter of 13 nm, an average secondary particle diameter of 19 nm, and a degree of association of 1.5.

[0080] <Preparation Example 4: Preparation of Silica Particle Organic Solvent Dispersion D4> In a 5L reaction vessel equipped with a stirrer and cooling function, a mixture of 2945g methanol, 373.15g pure water, 218g 29% ammonia water, and 5.4g colloidal silica (silica concentration: 12% by weight, average secondary particle size: 25nm) (solution A) was added. While stirring at 300rpm, a mixture of 79g methanol and 309g tetramethoxysilane (TMOS) (solution B) was added at a rate of 11mL / min while maintaining the reaction vessel temperature at 20°C to prepare a reaction solution and obtain a silica sol. 500g of the prepared silica sol was mixed with 385g of γ-butyrolactone (GBL) and stirred. The dispersion medium of the silica sol was replaced with γ-butyrolactone by vacuum distillation using a rotary evaporator. This prepared a silica particle organic solvent dispersion D4 (500g) with an SiO2 concentration of 8% by weight and a water concentration of 1% by weight or less. The obtained silica nanoparticles had an average primary particle diameter of 84 nm, an average secondary particle diameter of 153 nm, and a degree of association of 1.8.

[0081] <Preparation Example 5: Preparation of Silica Particle Organic Solvent Dispersion D5> 500 g of silica particle aqueous dispersion (Fuso Chemical Co., Ltd., Quattron PL-1, silica concentration 12 wt%) was mixed with 440 g of γ-butyrolactone (GBL) and stirred. The aqueous dispersion medium of the silica sol was replaced with γ-butyrolactone by vacuum distillation using a rotary evaporator. This prepared silica particle organic solvent dispersion D5 (500 g) with an SiO2 concentration of 12 wt% and a water concentration of 1 wt% or less. The average primary particle diameter of the obtained silica nanoparticles was 15 nm, the average secondary particle diameter was 40 nm, and the degree of association was 2.7.

[0082] <Preparation Example 6: Preparation of Silica Particle Organic Solvent Dispersion D6> A silica particle organic solvent dispersion D6 (500g) was prepared by adding 385g of γ-butyrolactone (GBL) to 500g of silica particle aqueous dispersion (Fuso Chemical Co., Ltd., Quattron PL-10H, silica concentration 23 wt%), stirring, and then replacing the aqueous dispersion medium of the silica sol with γ-butyrolactone by vacuum distillation using a rotary evaporator. The SiO2 concentration was 23 wt% and the water concentration was 1 wt% or less. The resulting silica nanoparticles had an average primary particle diameter of 90 nm, an average secondary particle diameter of 220 nm, and a degree of association of 2.4.

[0083] <Preparation Example 7: Preparation of Silica Particle Organic Solvent Dispersion D7> SIRPMA30WT%-K22 (30 wt% silica concentration PMA dispersion, average primary particle diameter 120 nm, average secondary particle diameter 250 nm, degree of association 2.1) manufactured by CIK Nanotech was used as is.

[0084] <Measurement of the average primary particle diameter of silica particles> Each silica particle organic solvent dispersion was pre-dried on a hot plate, and then heat-treated at 800°C for 1 hour to prepare samples for measurement. Measurements were performed using the carrier gas method with nitrogen gas in accordance with JIS Z 8830:2013. The BET specific surface area was measured by analyzing isothermal adsorption lines using the multi-point method with a QUANTACHROME AUTOSORB-1 (product name). As the evaluation device, the BET specific surface area was calculated as 2727 / BET specific surface area (m²), assuming a true specific gravity of silica of 2.2. 2 The average primary particle diameter was determined by calculating the value of ( / g).

[0085] <Average secondary particle diameter of silica particles> Using the silica particle organic solvent dispersions prepared in the above adjustment examples 1 to 7, the volume-based particle size distribution was measured by dynamic light scattering using a Microtrac MT3300EX manufactured by Nikkiso Co., Ltd., and the average secondary particle size (D50 volume%) was measured.

[0086] <Degree of association of silica particles> The degree of association of silica particles was determined using the following formula, based on the average primary particle diameter and average secondary particle diameter of the silica particles calculated by the method described above. Degree of association = (average secondary particle diameter) / (average primary particle diameter)

[0087] <<Preparation of Curable Resin Composition>> <Raw materials> (A) Carboxyl group-containing resin Carboxyl group-containing resin A1: synthesized by the method of Synthesis Example 1 above. Carboxyl group-containing resin A2: synthesized by the method of synthesis example 2 above. (B) Photopolymerization initiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, manufactured by IGM Resins. (C) Epoxy resin Dicyclopentadiene type epoxy resin HP-7200L DIC Corporation (D) Silica Silica particle organic solvent dispersion D1: Prepared by the method of Preparation Example 1 above. Silica particle organic solvent dispersion D2: Prepared by the method of Preparation Example 2 above. Silica particle organic solvent dispersion D3: Prepared by the method of Preparation Example 3 above. Silica particle organic solvent dispersion D4: Prepared by the method of Preparation Example 4 above. Silica particle organic solvent dispersion D5: Prepared by the method of Preparation Example 5 above. Silica particle organic solvent dispersion D6: Prepared by the method of Preparation Example 6 above. Silica particle organic solvent dispersion D7: Prepared by the method of Preparation Example 7 above. (D-2) Other silica Silica D2-1:SFP-20M (average secondary particle diameter 400nm), manufactured by Denka Co., Ltd. Silica D2-2:SO-C4 (average secondary particle size 1000nm), manufactured by Admatex Co., Ltd. Silica D2-3:SO-C5 (average secondary particle size 1600nm), manufactured by Admatex Co., Ltd. (E) Rubber particles Rubber particle E1: PARALOIDO EXL-2655 (average secondary particle diameter 500 nm), manufactured by Dow Chemical. Rubber particles E2:XER-91 (average secondary particle diameter 400nm), manufactured by JSR Corporation. ·Thermosetting catalyst Thermosetting catalyst 1: Melamine Thermosetting catalyst 2: Dicyandiamide DICY • Acrylate monomer Acrylate monomer: Dipentaerythritol hexaacrylate (DPHA), manufactured by Nippon Kayaku Co., Ltd. Note that the amounts of each component listed in Tables 1 and 2 all represent parts by mass on a solid content basis.

[0088] <Method for preparing a curable resin composition> For each example and comparative example of a curable resin composition, the various components listed in Tables 1 and 2 were blended in the proportions (parts by mass) shown in the tables. After pre-mixing with a stirrer, the mixture was kneaded in a bead mill to prepare the curable resin composition. The blending amounts of each component in Tables 1 and 2 are listed in terms of solid content mass. The stirring conditions for the stirrer were a rotation speed of 800 rpm, a stirring time of 10 mins, and a stirrer blade of 12 cm. A conical type K-8 bead mill (manufactured by Beura) was used, and the mixture was kneaded under the following conditions: zirconia beads, rotation speed of 1000 rpm, discharge rate of 20%, bead particle size of 0.65 mm, and packing rate of 88%.

[0089] <Preparation of dry film> Each of the curable resin compositions prepared in the above examples and comparative examples was applied to a 38 μm polyethylene terephthalate film using an applicator, and dried in a hot air circulating drying oven at 80°C for 10 minutes to produce a dry film having a resin layer with a thickness of 23 μm.

[0090] <<<Rating>>> The dry films for each example and each comparative example were evaluated as follows.

[0091] <<Resolution Evaluation>> A copper-clad laminate made of FR-4 1.6 mm thick copper foil with a thickness of 35 μm was subjected to copper etching equivalent to 1.0 μm using MEC's ​​CZ-8101B process. Dry films of each example and comparative example were then laminated onto the laminate using a vacuum laminator (CVP-300: Nikko Material Co., Ltd.) in the first chamber at 90°C under a vacuum pressure of 3 hPa and a vacuum time of 30 seconds, followed by pressing under a press pressure of 0.5 MPa and a press time of 30 seconds. Next, exposure was performed using an exposure apparatus equipped with a high-pressure mercury lamp for each aperture pattern. The exposure amount was adjusted using a step tablet (Photec 41 step) so that the gloss sensitivity was 10 steps. Then, the polyethylene terephthalate film was peeled off the photosensitive dry film to expose the photosensitive resin layer. After that, a 1% by mass Na2CO3 aqueous solution at 30°C was sprayed at a pressure of 2 kg / cm². 2 The substrate with this cured film was developed for 60 seconds under these conditions. 2 After UV irradiation under the specified conditions, the material was heat-cured at 170°C for 60 minutes. The aperture diameter of the resulting cured material was observed by SEM at a magnification of 1500x, and the presence or absence of halation and undercuts was evaluated according to the following criteria. The results are shown in Tables 1 and 2. <Evaluation Criteria> ◎: A good aperture diameter of 35 μm was obtained. ○: A good aperture diameter was obtained at 40 μm, but a good aperture diameter was not obtained at 35 μm. △: A good aperture diameter was obtained at 50 μm, but a good aperture diameter was not obtained at 40 μm. ×: A satisfactory aperture size could not be obtained with an aperture size of 50 μm.

[0092] <<Evaluation of circuit embedding capabilities>> A substrate with a copper circuit of L / S = 20 μm / 20 μm formed on it, with a copper thickness of 18 μm, was etched to a thickness equivalent to 1.0 μm using MEC's ​​CZ-8101B process. Dry films of each example and comparative example were then laminated onto the substrate using a vacuum laminator (CVP-300: Nikko Material Co., Ltd.) in the first chamber at 90°C under a vacuum pressure of 3 hPa and a vacuum time of 30 seconds. Afterward, pressing was performed under a press pressure of 0.5 MPa and a press time of 30 seconds. Next, exposure was performed using an exposure apparatus equipped with a high-pressure mercury lamp at each aperture pattern. The exposure amount was adjusted using a step tablet (Photec 41-step) so that the gloss sensitivity was 10 steps. Then, the polyethylene terephthalate film was peeled from the photosensitive dry film, exposing the photosensitive resin layer. Finally, a 1 mass% Na2CO3 aqueous solution at 30°C was sprayed at a pressure of 2 kg / cm². 2 The substrate with this cured film was developed for 60 seconds under these conditions. 2 After UV irradiation under these conditions, the material was heat-cured at 170°C for 60 minutes. The resulting cured material was observed using an optical microscope at a magnification of 500x, and the number of voids between the L / S layers was evaluated. The results are shown in Tables 1 and 2. <Evaluation Criteria> ○: No voids were observed. △: 1 to 10 voids were observed. ×: More than 11 voids were observed.

[0093] <<Insulation reliability (B-HAST resistance (L / S=10 / 10μm))>> A substrate with a comb-shaped pattern of L / S = 10 / 10 μm was formed on the substrate, and a cured film was fabricated in the same manner as the resolution evaluation substrate, except that the entire surface was exposed. HAST was then performed under the conditions of 130°C, 85% RH, applied voltage of 3.5 V, and in-cabin measurement. The evaluation criteria are as follows. The results are shown in Tables 1 and 2. <Evaluation Criteria> ◎: No abnormalities after 400 hours. ○: Short circuit occurred between 300 and 400 hours. △: Short circuit occurred between 200 and 300 hours. ×: Short circuit occurred in less than 200 hours.

[0094] <<Crack resistance>> On an evaluation substrate for FC - BGA formed with a pad pitch of 200 μm pitch, the dry films of each example and each comparative example were heat - laminated using a vacuum laminator (CVP - 300, manufactured by Nichco Materials Co., Ltd.). On the contrary, after adjusting the exposure amount so that the gloss sensitivity becomes 10 steps with a step tablet (Photec 41 steps), direct imaging exposure was performed with an aperture size of 80 μm. Then, the polyethylene terephthalate film was peeled off from the photosensitive dry film to expose the photosensitive resin layer, and a 1 mass% Na2CO3 aqueous solution at 30 °C was sprayed at a pressure of 2 kg / cm 2 under the conditions for 60 seconds to develop and obtain a pattern of the cured film. Further, after irradiating ultraviolet rays with an integrated exposure amount of 1000 mJ / cm 2 and then heating at 170 °C for 1 hour to cure. Then, Au plating treatment, solder bump formation, and Si chips were mounted to obtain an evaluation substrate. The evaluation substrate obtained as described above was placed in a thermal cycle machine in which a temperature cycle was performed between - 65 °C and 150 °C, and a TCT (Thermal Cycle Test) was performed. And the surface of the cured film at 500 cycles and 1000 cycles was observed. The judgment criteria are as follows. The results are shown in Tables 1 and 2. <Evaluation criteria> ◎: No abnormality at 1000 cycles ○: No abnormality at 500 cycles, cracks generated at 1000 cycles ×: Cracks generated at 500 cycles

[0095] <<Heat resistance>> A substrate having a cured film was produced in the same manner as the production of the resolution evaluation substrate except for full - surface exposure. The produced substrate was coated with a rosin - based flux and passed through a reflow furnace set at a maximum of 260 °C in advance, and the swelling and peeling of the cured coating film were evaluated. The evaluation criteria are as follows. The results are shown in Tables 1 and 2. <Evaluation criteria> ◎: No swelling or peeling even after passing through 10 times or more ○: No swelling or peeling occurred even after passing through 5 or more times but less than 10 times. △: No swelling or peeling occurred even after passing through the area 1 or more times but less than 5 times. ×: Swelling and peeling occurred after one use. <<Coating properties>> Dry films from each example and comparative example were cut to a size of 5 cm x 5 cm, and the surface of the dry film was observed using an optical microscope at a magnification of 500x to check for the presence and size of pinholes. The evaluation criteria were as follows. <Evaluation Criteria> ◎: No pinholes were observed. ○: Pinholes smaller than 10 μm were observed. △: Pinholes larger than 10 μm and smaller than 20 μm were observed. ×: Pinholes larger than 20 μm were observed.

[0096] [Table 1]

[0097] [Table 2]

Claims

1. A method for producing a curable resin composition, comprising a mixing step of mixing (A) a carboxyl group-containing resin, (B) a photopolymerization initiator, (C) a thermosetting resin, and (D) silica, The amount of silica (D) is 10 to 60% by mass relative to the total solid content of the curable resin composition. The (D) silica is spherical silica, The (D) silica includes (D-1) nanosilica, A method for producing a curable resin composition, characterized in that the (D-1) nanosilica satisfies the following requirements (1) and (2) before the mixing step. (1) The average secondary particle diameter is 200 nm or less. (2) The degree of association is 2.3 or less. The aforementioned average secondary particle diameter is the volume-average particle diameter measured by dynamic light scattering using a laser diffraction detector. The degree of association is calculated according to the following (Equation 1), and the average primary particle size of nanosilica is calculated according to the following (Equation 2). (Equation 1) Degree of association = Average secondary particle diameter of nanosilica / Average primary particle diameter of nanosilica (Equation 2) Average primary particle diameter of nanosilica = 6 / (True specific gravity × BET specific surface area measurement value)

2. The (D) silica further includes other silica (D-2) which is different from the (D-1) nanosilica and has an average secondary particle diameter of more than 200 nm. (D-2) The method for producing a curable resin composition according to claim 1, characterized in that the average secondary particle diameter of the other silica is the volume-average particle diameter measured by dynamic light scattering using a laser diffraction measuring instrument before the mixing step.

3. A method for producing a curable resin composition according to claim 2, characterized in that the average secondary particle size of the other silica (D-2) is 400 nm to 1600 nm.

4. A method for producing a curable resin composition according to any one of claims 1 to 3, characterized in that the amount of (D-1) nanosilica blended is 50% by mass or more relative to the total amount of (D) silica blended.

5. (E) A method for producing a curable resin composition according to any one of claims 1 to 4, further comprising the step of mixing rubber particles.

6. A method for producing a dry film, characterized by comprising the step of applying a curable resin composition produced by the method for producing a curable resin composition according to any one of claims 1 to 5 onto a film and drying it to obtain a resin layer on the film.

7. A method for producing a cured product, characterized by including a step of curing a resin layer of a curable resin composition produced by a method for producing a curable resin composition according to any one of claims 1 to 5, or a dry film produced by a method for producing a dry film according to claim 6.

8. A method for manufacturing an electronic component, characterized by including the method for manufacturing a cured product as described in claim 7.

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