Laminated structure, cured product, and printed wiring board

Abstract

[Problem] To provide a laminated structure that can be laminated by both a conveyance-type laminator and a vacuum roll laminator. [Solution] A laminated structure according to the present invention comprises a first film and a resin layer formed on the first film, the structure being characterized in that: the resin layer is composed of a dry coating film of a photosensitive resin composition; the melt viscosity of the photosensitive resin composition at 50ºC is 1000-20,000 Pa·s; the melt viscosity of the photosensitive resin composition at 100ºC is 50-2000 Pa·s; and the film thickness of the resin layer is greater than 80 μm and less than or equal to 300 μm.

Description

Laminated structure, cured product, and printed wiring board

[0001] The present invention relates to a laminate structure. The present invention also relates to a cured product formed using the laminate structure and a printed wiring board including the cured product.

[0002] In general, when mounting electronic components on a printed wiring board used in electronic devices, a solder resist layer is formed on the substrate on which the circuit pattern is formed in an area other than the connection holes in order to prevent solder from adhering to unnecessary areas.

[0003] In recent years, electronic devices have become lighter, thinner, shorter, and smaller, resulting in higher precision and higher density of printed wiring boards. Currently, solder resist layers are mainly formed using a so-called photosolder resist, in which a photosensitive resin composition is applied to a substrate, dried, exposed to light, and developed to form a pattern, and the patterned resin is then fully cured by heating or light irradiation.

[0004] It has also been proposed to form a solder resist layer using a laminate structure (photosensitive film) including a photosensitive resin layer (photosensitive layer) without using the liquid photosensitive resin composition described above. Such a laminate structure generally includes a photosensitive resin layer formed from a photosensitive resin composition on a support film. Such a laminate structure can be laminated to a wiring board by thermocompression bonding, and the support film can be peeled off and developed before exposure or after exposure from the support film side, thereby forming a patterned solder resist layer.

[0005] For example, Patent Document 1 discloses a photosensitive film having at least a support and a photosensitive layer on the support, wherein the photosensitive layer is made of a photosensitive composition containing at least a binder having a crosslinkable group, the amount of a catalyst remaining for introducing the crosslinkable group into the binder is 200 ppm or less, and the melt viscosity at 24° C. is 1.0×10 ５ Pa・s~1.0×10 ７ Pa s, and the melt viscosity at 60°C to 90°C is 1.0 × 10 ２ Pa・s~5.0×10４ The photosensitive film is characterized in that the tension when the photosensitive film is wound into a roll is 1.6 kg / 10 cm or more, and the roll has end pressers on both end surfaces. Furthermore, Patent Document 1 describes laminating a photosensitive film having a thin photosensitive layer with a thickness of 30 μm onto a substrate using a vacuum laminator.

[0006] JP 2009-237494 A

[0007] However, the inventors have found that when the photosensitive layer of a photosensitive film is thick (e.g., greater than 80 μm), poor embedding, such as air bubbles trapped between the substrate and the photosensitive layer, occurs during lamination, depending on the type of laminator. Specifically, the inventors have found that when the melt viscosity of a photosensitive resin composition is high at low temperatures (e.g., 50°C), poor embedding occurs due to insufficient resin flow during lamination using a vacuum roll laminator. On the other hand, the inventors have found that when the melt viscosity of a photosensitive resin composition is low at high temperatures (e.g., 100°C), air trapping (air trapped in the molten resin that cannot be removed even by vacuuming) occurs during lamination using a conveyor laminator.

[0008] Therefore, an object of the present invention is to provide a laminated structure that can be laminated using both a conveyor laminator and a vacuum roll laminator. Another object of the present invention is to provide a cured product formed using the laminated structure and a printed wiring board including the same.

[0009] The present inventors have found that in a laminate structure including a first film and a resin layer formed on the first film and consisting of a dried coating of a photosensitive resin composition, even when the resin layer has a thickness of more than 80 μm and not more than 300 μm, it is possible to provide a laminate structure that can be laminated using both a conveyor-type laminator and a vacuum roll laminator by adjusting the melt viscosity of the photosensitive resin composition at 50° C. and 100° C. The present invention is based on this finding.

[0010] That is, the present invention provides the following inventions. [1] A laminate structure comprising a first film and a resin layer formed on the first film, wherein the resin layer is made of a dried coating film of a photosensitive resin composition, wherein the photosensitive resin composition has a melt viscosity at 50°C of 1,000 Pa·s or more and 50,000 Pa·s or less and a melt viscosity at 100°C of 50 Pa·s or more and 2,000 Pa·s or less, and the resin layer has a thickness of more than 80 μm and 300 μm or less. [2] The laminate structure according to [1], wherein the photosensitive resin composition has a melt viscosity at 50°C of 3,000 Pa·s or more and 40,000 Pa·s or less and a melt viscosity at 100°C of 100 Pa·s or more and 1,500 Pa·s or less. [3] The laminate structure according to [1] or [2], wherein the ratio of the melt viscosity at 50°C of the photosensitive resin composition to the melt viscosity at 100°C is 10 or more and 200 or less. [4] The laminate structure according to any one of [1] to [3], wherein the photosensitive resin composition contains (A) a curable resin, (B) a photopolymerization initiator, and (C) an inorganic filler. [5] The laminate structure according to any one of [1] to [4], further comprising a second film on the resin layer. [6] The laminate structure according to any one of [1] to [5], which is used for lamination using both a conveyor laminator and a vacuum roll laminator. [7] A cured product obtained by curing the resin layer of the laminate structure according to any one of [1] to [6]. [8] A printed wiring board comprising the cured product according to [7].

[0011] According to the present invention, it is possible to provide a laminate structure that can be laminated using both a conveyor-type laminator and a vacuum roll laminator. Also, according to the present invention, it is possible to provide a cured product formed using the laminate structure and a printed wiring board including the same.

[0012] 1 is a schematic cross-sectional view showing one embodiment of a laminated structure of the present invention.

[0013] <Laminated Structure> The laminated structure according to the present invention comprises a first film and a resin layer formed on the first film, and may further comprise a second film on the resin layer.

[0014] The laminate structure according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view showing one embodiment of the laminate structure according to the present invention. The laminate structure 1 shown in Fig. 1 comprises a first film 10, a resin layer 20 provided on one side of the first film 10, and a second film 30 provided on the side of the resin layer 20 opposite to the side on which the first film 10 is provided. Each of the components constituting the laminate structure according to the present invention will be described below.

[0015] [Resin Layer] The resin layer is a photosensitive layer that is made of a dried coating film of a photosensitive resin composition and that is cured by light irradiation. In the present invention, the resin layer is preferably a single layer.

[0016] The thickness of the resin layer is more than 80 μm and not more than 300 μm, preferably 85 μm or more and 250 μm or less, and more preferably 90 μm or more and 200 μm or less. In the present invention, even when the resin layer has a thickness as large as the above numerical range, lamination can be performed using both a conveyor-type laminator and a vacuum roll laminator.

[0017] (Photosensitive resin composition) The melt viscosity of the photosensitive resin composition at 50 ° C. is 1000 Pa s or more and 50,000 Pa s or less, preferably 3,000 Pa s or more and 40,000 Pa s or less, more preferably 5,000 Pa s or more and 30,000 Pa s or less, even more preferably 10,000 Pa s or more and 25,000 Pa s or less, and even more preferably 15,000 Pa s or more and 20,000 Pa s or less. The melt viscosity of the photosensitive resin composition at 100 ° C. is 50 Pa s or more and 2,000 Pa s or less, preferably 100 Pa s or more and 1,500 Pa s or less, more preferably 150 Pa s or more and 1,250 Pa s or less, and even more preferably 200 Pa s or more and 1,000 Pa s or less. As long as the melt viscosity of the photosensitive resin composition at 50°C and 100°C is within the above numerical range, lamination can be performed using both a conveying laminator and a vacuum roll laminator, even if the resin layer has a thick film thickness within the above numerical range. In the present invention, the melt viscosity of the photosensitive resin composition at 50°C is a value measured using a dynamic viscoelasticity measuring device, which is a rotational rheometer.

[0018] The ratio of the melt viscosity of the photosensitive resin composition at 50°C to the melt viscosity at 100°C (melt viscosity at 50°C (Pa s) / melt viscosity at 100°C (Pa s)) is preferably 10 or more and 200 or less, more preferably 10 or more and 100 or less, and even more preferably 10 or more and 50 or less. When the ratio of the melt viscosity of the photosensitive resin composition at 50°C to the melt viscosity at 100°C is within the above numerical range, the change in melt viscosity due to temperature can be suppressed, and the lamination properties can be improved in both a conveyor-type laminator and a vacuum roll laminator.

[0019] The photosensitive resin composition preferably contains (A) a curable resin, (B) a photopolymerization initiator, and (C) an inorganic filler, and may further contain a photopolymerizable monomer, a colorant, an organic solvent, and other additive components. In the present invention, the melt viscosity of the photosensitive resin composition at 50°C and 100°C can be adjusted to the above-mentioned preferred numerical range by adjusting the type and amount of each component contained in the photosensitive resin composition. Each component of the photosensitive resin composition will be described in detail below.

[0020] (A) Curable Resin The curable resin preferably contains an alkali-soluble resin, and may further contain a thermosetting resin.

[0021] (Alkali-Soluble Resin) The alkali-soluble resin has an alkali-soluble group that is soluble in an alkaline aqueous solution. The alkali-soluble group is, for example, any one of a phenolic hydroxyl group, a thiol group, and a carboxyl group. Examples of alkali-soluble resins include compounds having two or more phenolic hydroxyl groups, carboxyl group-containing resins, compounds having a phenolic hydroxyl group and a carboxyl group, and compounds having two or more thiol groups. When the alkali-soluble resin is a carboxyl group-containing resin or a phenolic resin, adhesion to the substrate is improved. In particular, when the alkali-soluble resin is a carboxyl group-containing resin, developability is excellent. The carboxyl group-containing resin is preferably a carboxyl group-containing photosensitive resin having an ethylenically unsaturated group, but may also be a carboxyl group-containing resin without an ethylenically unsaturated group. When using only a carboxyl group-containing resin without an ethylenically unsaturated group, a photopolymerizable monomer, as described below, must be used in combination to make the composition photosensitive.

[0022] Specific examples of carboxyl group-containing resins include the following compounds (which may be either oligomers or polymers): (1) Carboxyl group-containing resins 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; (2) Carboxyl group-containing urethane resins obtained by polyaddition reaction of a diisocyanate such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate with a carboxyl group-containing dialcohol compound such as dimethylolpropionic acid or dimethylolbutanoic acid, or a diol compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group. (3) Carboxy-terminated urethane resins obtained by reacting acid anhydrides with the terminals of urethane resins obtained by polyaddition reaction of diisocyanate compounds such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with 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. (4) Carboxy-terminated urethane resins obtained by polyaddition reaction of diisocyanates with (meth)acrylates or partially acid anhydride-modified products thereof of bifunctional epoxy resins such as bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bixylenol epoxy resins, and biphenol epoxy resins, carboxyl-terminated dialcohol compounds, and diol compounds. (5) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as a hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (4) above.(6) A carboxyl group-containing urethane resin obtained by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (4) above, resulting in a (meth)acrylate-terminated carboxyl group-containing resin (acid-modified epoxy acrylate resin) obtained by reacting a multifunctional epoxy resin with (meth)acrylic acid to add a dibasic acid anhydride, such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride, to the hydroxyl groups present in the side chain. (8) A carboxyl group-containing resin (acid-modified epoxy acrylate resin) obtained by reacting a multifunctional epoxy resin, in which the hydroxyl groups of a bifunctional epoxy resin have been further epoxidized with epichlorohydrin, with (meth)acrylic acid to add a dibasic acid anhydride to the resulting hydroxyl groups. (9) A carboxyl group-containing polyester resin obtained by reacting a multifunctional oxetane resin with a dicarboxylic acid to add a dibasic acid anhydride to the resulting primary hydroxyl groups. (10) A carboxyl group-containing 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 obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride. (11) A carboxyl group-containing resin 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, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride. (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 groups of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride.(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, α-methylglycidyl (meth)acrylate, etc., to the carboxyl group-containing resin described in (1) to (12) above.

[0023] Examples of compounds having a phenolic hydroxyl group include compounds having a biphenyl skeleton or a phenylene skeleton, or both of these skeletons, and phenolic resins having various skeletons synthesized using phenol, orthocresol, para-cresol, meta-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, catechol, resorcinol, hydroquinone, methylhydroquinone, 2,6-dimethylhydroquinone, trimethylhydroquinone, pyrogallol, phloroglucinol, etc. Examples of the compound having a phenolic hydroxyl group include known and commonly used phenolic resins such as phenol novolac resin, alkylphenol volac resin, bisphenol A novolac resin, dicyclopentadiene-type phenolic resin, Xylok-type phenolic resin, terpene-modified phenolic resin, polyvinylphenols, bisphenol F, bisphenol S-type phenolic resin, poly-p-hydroxystyrene, condensates of naphthol and aldehydes, and condensates of dihydroxynaphthalene and aldehydes.

[0024] As the alkali-soluble resin, one of the above compounds can be used alone, or two or more of them can be used in combination.

[0025] In this specification, (meth)acrylate is a general term that refers to acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

[0026] The acid value of the alkali-soluble resin is preferably 30 mgKOH / g or more and 150 mgKOH / g or less. By making the acid value of the carboxyl group-containing photosensitive resin 30 mgKOH / g or more, alkaline development becomes good. Furthermore, by making the acid value 150 mgKOH / g or less, it becomes easy to draw a good resist pattern.

[0027] The weight-average molecular weight of the alkali-soluble resin varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. By making the weight-average molecular weight 2,000 or more, tack-free performance and resolution can be improved. Furthermore, by making the weight-average molecular weight 150,000 or less, developability and storage stability can be improved.

[0028] The amount of the alkali-soluble resin is preferably 30% by mass or more and 70% by mass or less, more preferably 35% by mass or more and 60% by mass or less, calculated as solid content, relative to the total amount of the photosensitive resin composition. When the amount of the alkali-soluble resin is within the above range, it is possible to remove the unexposed area without leaving any residue during development, resulting in good resolution.

[0029] (Thermosetting Resin) The thermosetting resin may be any resin that reacts with the functional group of the curable resin by heating, hardens, and exhibits electrical insulation, and examples thereof include epoxy compounds, oxetane compounds, melamine resins, silicone resins, etc. In particular, in the present invention, epoxy compounds and oxetane compounds can be preferably used, and these may be used in combination.

[0030] As the epoxy compound, known and commonly used compounds having one or more epoxy groups can be used, with compounds having two or more epoxy groups being preferred. Examples include monoepoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl (meth)acrylate; bisphenol A epoxy resins, bisphenol S epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, alicyclic epoxy resins; trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4'-diglycidyl ether, 1,6-hexanediol diglycidyl ether, diglycidyl ether of ethylene glycol or propylene glycol, sorbitol polyglycidyl ether, tris(2,3-epoxypropyl)isocyanurate, and triglycidyl tris(2-hydroxyethyl)isocyanurate, all of which have two or more epoxy groups per molecule. These compounds can be used alone or in combination depending on the required properties.

[0031] Examples of epoxy resins include jER828, jER834, jER1001, and jER1004 manufactured by Mitsubishi Chemical Corporation, EPICLON 840, 850, 850-S, 1050, and 2055 manufactured by DIC Corporation, Epotohto YD-011, YD-013, YD-127, and YD-128 manufactured by Nippon Steel Chemical & Material Co., Ltd., and D.E.R. 317, D.E.R. 331, D.E.R. 661, and D.E.R. 662 manufactured by The Dow Chemical Company. bisphenol A type epoxy resins such as ESA-011, ESA-014, ELA-115, and ELA-128 (all trade names) manufactured by Sumitomo Chemical Co., Ltd.; jERYL903 manufactured by Mitsubishi Chemical Corporation, EPICLON 152 and 165 manufactured by DIC Corporation, Epotohto YDB-400 and YDB-500 manufactured by Nippon Steel Chemical & Material Co., Ltd., D.E.R.542 manufactured by Dow Chemical Co., Ltd., and Sumi-Epoxy ESB-400 and ESB-700 (all trade names) manufactured by Sumitomo Chemical Co., Ltd.; jER152 and jER154 manufactured by Mitsubishi Chemical Corporation, and D.E.N.431 and D.E.N.432 manufactured by Dow Chemical Co., Ltd. 438, EPICLON N-730, N-770, N-865 manufactured by DIC Corporation, Epotohto YDCN-701, YDCN-704 manufactured by Nippon Steel Chemical & Material Co., Ltd., EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, RE-306, NC-3000, NC-3000L manufactured by Nippon Kayaku Co., Ltd., Sumi-Epoxy ESCN-195X, ESCN-220 manufactured by Sumitomo Chemical Co., Ltd., YDCN-700-2, YDCN-700-3, YDCN-700-5, YDCN-700-7, YDCN-700-10, YDCN-704 YDCN-704A manufactured by Nippon Steel Chemical & Material Co., Ltd., EPICLON manufactured by DIC Corporation Novolac epoxy resins such as N-680, N-690, and N-695 (all trade names); bisphenol F epoxy resins such as EPICLON 830 manufactured by DIC Corporation, jER807 manufactured by Mitsubishi Chemical Corporation, and Epotohto YDF-170, YDF-175, and YDF-2004 manufactured by Nippon Steel Chemical & Material Co., Ltd. (all trade names);Hydrogenated bisphenol A type epoxy resins such as Epotohto ST-2004, ST-2007, and ST-3000 (trade names) manufactured by Nippon Steel Chemical & Material Co., Ltd., and YX8034 manufactured by Mitsubishi Chemical Corporation; glycidylamine type epoxy resins such as jER604 manufactured by Mitsubishi Chemical Corporation, Epotohto YH-434 manufactured by Nippon Steel Chemical & Material Co., Ltd., and Sumi-Epoxy ELM-120 manufactured by Sumitomo Chemical Co., Ltd. (all trade names); hydantoin type epoxy resins; Celoxide 2021 manufactured by Daicel Corporation (some alicyclic epoxy resins such as YL-933 manufactured by Mitsubishi Chemical Corporation and EPPN-501 and EPPN-502 manufactured by Nippon Kayaku Co., Ltd. (all trade names); trihydroxyphenylmethane type epoxy resins such as YL-6056, YX-4000, and YL-6121 (all trade names) manufactured by Mitsubishi Chemical Corporation, bixylenol type or biphenol type epoxy resins or mixtures thereof; EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by ADEKA Corporation, and EXA-151 manufactured by DIC Corporation Bisphenol S type epoxy resins such as jER157S (trade name) manufactured by Mitsubishi Chemical Corporation; bisphenol A novolac type epoxy resins such as jERYL-931 (all trade names) manufactured by Mitsubishi Chemical Corporation; tetraphenylolethane type epoxy resins such as TEPIC (all trade names) manufactured by Nissan Chemical Industries, Ltd.; diglycidyl phthalate resins such as BLEMMER DGT manufactured by NOF Corporation; tetraglycidyl xylenolate resins such as ZX-1063 manufactured by Nippon Steel Chemical & Material Co., Ltd. naphthalene skeleton-containing epoxy resins such as ESN-190 and ESN-360 manufactured by Nippon Steel Chemical & Material Co., Ltd., and HP-4032, EXA-4750, and EXA-4700 manufactured by DIC Corporation; dicyclopentadiene skeleton-containing epoxy resins such as HP-7200 and HP-7200H manufactured by DIC Corporation; glycidyl methacrylate copolymer epoxy resins such as CP-50S and CP-50M manufactured by NOF Corporation; and cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resins;Examples of the epoxy resin include, but are not limited to, CTBN-modified epoxy resins (e.g., YR-102 and YR-450 manufactured by Nippon Steel Chemical & Material Co., Ltd.). These epoxy resins may be used alone or in combination of two or more.

[0032] Specific examples of the oxetane compound include 3-ethyl-3-hydroxymethyloxetane (OXT-101, manufactured by Toagosei Co., Ltd.), 3-ethyl-3-(phenoxymethyl)oxetane (OXT-211, manufactured by Toagosei Co., Ltd.), 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane (OXT-212, manufactured by Toagosei Co., Ltd.), 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene (OXT-121, manufactured by Toagosei Co., Ltd.), and bis(3-ethyl-3-oxetanylmethyl)ether (OXT-221, manufactured by Toagosei Co., Ltd.). Further examples include phenol novolac-type oxetane compounds. These oxetane compounds may be used in combination with the above-mentioned epoxy compounds, or may be used alone.

[0033] The amount of the thermosetting resin is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, calculated as solid content, relative to the total amount of the photosensitive resin composition. If the amount of the thermosetting resin is within the above range, a crosslinked body is appropriately formed after the thermosetting reaction, resulting in good heat resistance, such as solder heat resistance and high-temperature storage resistance.

[0034] ((B) Photopolymerization initiator) The photopolymerization initiator is used to react the above-mentioned alkali-soluble resin or the photopolymerizable monomer described below by exposure to light. Any known photopolymerization initiator can be used. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0035] Specific examples of the photopolymerization initiator 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-trimethylphenylphosphine oxide. bisacylphosphine oxides such as 2,6-dimethoxybenzoyldiphenylphosphine oxide, 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-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloyl monoacylphosphine oxides such as phenylphosphinic acid isopropyl ester and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one hydroxyacetophenones such as benzoin, benzil, 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, Michler'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-hydroxycyclohexyl phenyl 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 acetophenones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, Anthraquinones such as 2-aminoanthraquinone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzoic acid esters such as ethyl 4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate and p-dimethylbenzoic acid ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyl oxime esters such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and titanocenes such as bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, and the like.

[0036] Commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, 369, 369E, and 379 manufactured by IGM Resins. Commercially available acylphosphine oxide photopolymerization initiators include Omnirad 819 manufactured by IGM Resins. Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan Ltd., N-1919, ADEKA Arcles NCI-831 and NCI-831E manufactured by ADEKA Corporation, and TR-PBG-304 manufactured by Changzhou New Advanced Electronic Materials Co., Ltd.

[0037] The amount of the photopolymerization initiator, calculated as solid content, relative to 100 parts by mass of the alkali-soluble resin is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 18 parts by mass, and even more preferably 1 to 15 parts by mass. When the amount is 0.1 part by mass or more, the photocurability of the resin composition is good and film properties such as chemical resistance are also good, while when the amount is 20 parts by mass or less, light absorption at the surface of the resist film (cured film) is good and deep curing is less likely to decrease.

[0038] A photoinitiator aid or sensitizer may be used in combination with the above-described photopolymerization initiator. Examples of the photoinitiator aid or sensitizer 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 can improve deep curing properties. While these compounds may be used as photopolymerization initiators, it is preferable to use them in combination with a photopolymerization initiator. Furthermore, one type of photoinitiator aid or sensitizer may be used alone, or two or more types may be used in combination.

[0039] (Photopolymerizable Monomer) The photopolymerizable monomer is a monomer having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers that can be used include known and commonly used photopolymerizable oligomers and photopolymerizable vinyl monomers. One type of photopolymerizable monomer may be used alone, or two or more types may be used in combination. Furthermore, the photopolymerizable monomer can also be used as a reactive diluent to adjust the viscosity of the photosensitive resin composition.

[0040] Examples of photopolymerizable oligomers include unsaturated polyester oligomers and (meth)acrylate oligomers. Examples of (meth)acrylate oligomers include epoxy (meth)acrylates such as phenol novolac epoxy (meth)acrylate, cresol novolac epoxy (meth)acrylate, and bisphenol-type epoxy (meth)acrylate, as well as urethane (meth)acrylate, epoxy urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and polybutadiene-modified (meth)acrylate. In this specification, "(meth)acrylate" is a general term referring to acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

[0041] Examples of the photopolymerizable vinyl monomer include known and commonly used ones, such as polyfunctional allyl compounds such as triallyl isocyanurate, diallyl phthalate, and diallyl isophthalate; alkylene polyol poly(meth)acrylates such as ethylene glycol di(meth)acrylate, butanediol di(meth)acrylates, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; ) acrylate; polyoxyalkylene glycol poly(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane tri(meth)acrylate; poly(meth)acrylates such as hydroxypivalic acid neopentyl glycol ester di(meth)acrylate; and isocyanurate-type poly(meth)acrylates such as tris[(meth)acryloxyethyl]isocyanurate.

[0042] The amount of the photopolymerizable monomer is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 45 parts by mass or less, in terms of solid content, relative to 100 parts by mass of the alkali-soluble resin. When the amount of the photopolymerizable monomer is within the above range, curing of the exposed area proceeds sufficiently, and sufficient development resistance is exhibited during development, resulting in good resolution.

[0043] (C) Inorganic Filler) As the inorganic filler, conventionally known inorganic fillers can be used. Examples of inorganic fillers that can be used include silica, crystalline silica, Neuburg silica, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, aluminum hydroxide, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, and zinc oxide.

[0044] The inorganic filler may be surface-treated to enhance dispersibility in the photosensitive resin composition. The use of a surface-treated filler can suppress aggregation. The surface treatment method is not particularly limited, and any known or commonly used method may be used. However, it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, such as a coupling agent having a curable reactive group as an organic group.

[0045] Examples of coupling agents that can be used include silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents. Among these, silane-based coupling agents are preferred. Examples of such 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. These can be used alone or in combination. It is preferred that these silane-based coupling agents are immobilized on the surface of the filler in advance by adsorption or reaction. Here, the amount of the coupling agent to be treated with respect to 100 parts by mass of the inorganic filler is preferably 0.5 to 10 parts by mass.

[0046] The amount of inorganic filler to be blended is preferably 1 part by mass or more and 300 parts by mass or less, more preferably 5 parts by mass or more and 150 parts by mass or less, in terms of solid content, relative to 100 parts by mass of the alkali-soluble resin. When the amount of inorganic filler to be blended is within the above range, thermal properties such as solder heat resistance and high-temperature storage resistance are improved.

[0047] (Colorant) As the colorant, any known colorant such as red, blue, green, yellow, or black can be used, and any of pigments, dyes, and colorants may be used. However, from the viewpoint of reducing the environmental load and having little effect on the human body, a colorant that does not contain halogen is preferred.

[0048] Red colorants include monoazos, disazos, azo lakes, benzimidazolone, perylene, diketopyrrolopyrrole, condensed azos, anthraquinones, and quinacridones, and specific examples thereof include those having the following Color Index (C.I., published by The Society of Dyers and Colorists) numbers:

[0095] Examples of monoazo red colorants include Pigment Red 1, 2, 3, 4, 5, 6, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 112, 114, 146, 147, 151, 170, 184, 187, 188, 193, 210, 245, 253, 258, 266, 267, 268, and 269. Examples of disazo red colorants include Pigment Red 37, 38, and 41. Examples of monoazo lake-based red colorants include Pigment Red 48:1, 48:2, 48:3, 48:4, 49:1, 49:2, 50:1, 52:1, 52:2, 53:1, 53:2, 57:1, 58:4, 63:1, 63:2, 64:1, and 68. Examples of benzimidazolone-based red colorants include Pigment Red 171, 175, 176, 185, and 208. Examples of perylene-based red colorants include Solvent Red 135, 179, Pigment Red 123, 149, 166, 178, 179, 190, 194, and 224. Examples of diketopyrrolopyrrole red colorants include Pigment Red 254, 255, 264, 270, and 272. Examples of condensed azo red colorants include Pigment Red 220, 144, 166, 214, 220, 221, and 242. Examples of anthraquinone red colorants include Pigment Red 168, 177, and 216, and Solvent Red 52, 149, 150, and 207. Examples of quinacridone red colorants include Pigment Red 122, 202, 206, 207, and 209.

[0049] Blue colorants include phthalocyanine-based and anthraquinone-based ones, and pigment-based ones include compounds classified as pigments, such as Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, and 60. Dye-based ones include Solvent Blue 35, 63, 67, 68, 70, 83, 87, 94, 97, 122, and 136. In addition to the above, metal-substituted or unsubstituted phthalocyanine compounds can also be used.

[0050] Examples of yellow colorants include monoazo, disazo, condensed azo, benzimidazolone, isoindolinone, and anthraquinone. Examples of anthraquinone yellow colorants include Solvent Yellow 163, Pigment Yellow 24, 108, 193, 147, 199, and 202. Examples of isoindolinone yellow colorants include Pigment Yellow 110, 109, 139, 179, and 185. Examples of condensed azo yellow colorants include Pigment Yellow 93, 94, 95, 128, 155, 166, and 180. Examples of benzimidazolone yellow colorants include Pigment Yellow 120, 151, 154, 156, 175, and 181. Examples of monoazo yellow colorants include Pigment Yellow 1, 2, 3, 4, 5, 6, 9, 10, 12, 61, 62, 62:1, 65, 73, 74, 75, 97, 100, 104, 105, 111, 116, 167, 168, 169, 182, and 183. Examples of disazo yellow colorants include Pigment Yellow 12, 13, 14, 16, 17, 55, 63, 81, 83, 87, 126, 127, 152, 170, 172, 174, 176, 188, and 198.

[0051] Examples of black colorants include carbon black and Pigment Black 1, 6, 7, 8, 9, 10, 11, 12, 13, 18, 20, 25, 26, 28, 29, 30, 31, and 32.

[0052] Other colorants such as purple, orange, brown, and white may also be added. Specific examples include C.I. Pigment Violet 19, 23, 29, 32, 36, 38, and 42, Solvent Violet 13 and 36, C.I. Pigment Orange 1, 5, 13, 14, 16, 17, 24, 34, 36, 38, 40, 43, 46, 49, 51, 61, 63, 64, 71, and 73, C.I. Pigment Brown 23 and 25, and titanium oxide.

[0053] The amount of the colorant to be added is not particularly limited, but is preferably 0.1 to 10 parts by mass in terms of solid content per 100 parts by mass of the alkali-soluble resin.

[0054] [Organic Solvent] The photosensitive resin composition may contain an organic solvent to adjust the viscosity. Examples of the organic solvent 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. These organic solvents can be used alone or in combination of two or more.

[0055] [Other Additive Components] The photosensitive resin composition may further contain, as necessary, components such as elastomers, mercapto compounds, urethanization catalysts, thixotropic agents, adhesion promoters, block copolymers, chain transfer agents, polymerization inhibitors, copper inhibitors, antioxidants, rust inhibitors, thickeners such as organic bentonite and montmorillonite, at least one of silicone-based, fluorine-based, and polymer-based antifoaming agents and leveling agents, and flame retardants such as phosphinates, phosphate ester derivatives, and phosphorus compounds such as phosphazene compounds. These may be known in the field of electronic materials.

[0056] (First Film) The first film supports the resin layer (i.e., a dried coating film made of a photosensitive resin composition) and adheres to the resin layer when the laminate structure is integrally molded by laminating it onto a substrate by heating or the like so that the resin layer side of the laminate structure is in contact with the substrate. The first film may be peeled from the laminate structure in a step after lamination. In the present invention, it is preferable that the first film is peeled from the laminate structure in a step after exposure.

[0057] The first film can be any film without particular limitation, and examples of films that can be preferably used include polyester films such as polyethylene terephthalate and polyethylene naphthalate, and films made of thermoplastic resins such as polyimide films, polyamideimide films, polypropylene films, and polystyrene films, but among these, polyester films are preferably used from the viewpoints of optical properties, heat resistance, mechanical strength, handleability, etc. The first film may be a single layer, or may be a laminate of two or more layers.

[0058] Furthermore, it is preferable to use the above-mentioned thermoplastic resin film which has been oriented uniaxially or biaxially in order to improve its strength.

[0059] The thickness of the first film is not particularly limited, but may be appropriately selected depending on the application within the range of, for example, 10 to 150 μm.

[0060] (Second Film) The laminate structure according to the present invention may be provided with a second film on the other side of the resin layer (the side opposite to the first film) for the purposes of preventing adhesion of dust and the like to the surface of the resin layer and improving handleability. The second film is peeled off from the laminate structure before lamination when the laminate structure is integrally molded by laminating it by heating or the like so that the resin layer side of the laminate structure is in contact with a substrate.

[0061] As the second film, for example, a film made of the above-mentioned thermoplastic resin can be suitably used, as in the first film. In addition, in order to make it easier to peel off the second film when using the laminated structure, the surface of the second film that comes into contact with the resin layer may be subjected to the above-mentioned release treatment.

[0062] The thickness of the second film is not particularly limited, but may be appropriately selected depending on the application within the range of, for example, 10 to 150 μm.

[0063] The surface of the second film that comes into contact with the resin layer may be subjected to a release treatment, for example, by applying a coating liquid prepared by dissolving or dispersing a release agent such as waxes, silicone wax, alkyd resins, urethane resins, melamine resins, or silicone resins in an appropriate solvent to the surface of the second film by a known method such as a coating method such as roll coating or spray coating, gravure printing, or screen printing, and drying the coating liquid.

[0064] [Method for Manufacturing Cured Product and Printed Wiring Board] The cured product of the present invention can be obtained by curing the resin layer (dried coating of the photosensitive resin composition) of the laminate structure. A method for forming a cured product and a method for manufacturing a printed wiring board having the cured product (cured coating) on ​​a substrate on which a circuit pattern has been formed will be described. As an example, a method for manufacturing a printed wiring board using a laminate structure having a second film will be described. First, i) the second film is peeled from the laminate structure to expose the resin layer, ii) the resin layer of the laminate structure is attached to the substrate on which the circuit pattern has been formed, iii) exposure is performed through the first film of the laminate structure, iv) the first film is peeled from the laminate structure and developed to form a patterned resin layer on the substrate, and v) the patterned resin layer is cured by light irradiation or heat to form a cured coating, thereby forming a printed wiring board. It goes without saying that when a laminate structure without a second film is used, the second film peeling step (step i) is unnecessary. Each step will be described below.

[0065] First, the second film is peeled from the laminate structure to expose the resin layer, and the resin layer of the laminate structure is laminated onto a substrate on which a circuit pattern is formed. Examples of substrates on which a circuit pattern is formed include printed wiring boards and flexible printed wiring boards on which circuits have been pre-formed, as well as copper-clad laminates of all grades (e.g., FR-4) made of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, copper-clad laminates for high-frequency circuits made of fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate ester, and the like, as well as polyimide films, PET films, glass substrates, ceramic substrates, wafer plates, and the like.

[0066] As a method for laminating the resin layer of the laminated structure onto the circuit board, both a conveyor type laminator and a vacuum roll laminator can be used.

[0067] A vacuum roll laminator is a device that continuously laminates a laminate structure onto a substrate in a vacuum. By using a vacuum roll laminator, it is possible to laminate a laminate structure onto an uneven substrate without introducing air bubbles or dust. Furthermore, laminating in a vacuum also eliminates contamination. Using a vacuum roll laminator makes it possible to manufacture long substrates.

[0068] The conditions for the vacuum roll laminator can be appropriately adjusted depending on the thickness of the resin layer of the laminated structure and the melt viscosity of the photosensitive resin composition at 50° C. and 100° C. For example, the conditions for the vacuum roll laminator are a temperature of 80 to 90° C. and a pressure of 3 to 5 kgf / cm. ２ The reduced pressure condition is preferably 10 to 100 Pa.

[0069] A conveyor laminator is a laminator device that is based on single-substrate processing. It bonds a laminated structure to a substrate that fits inside a vacuum chamber, removes air bubbles using a vacuum, and then bonds the laminated structure to an uneven substrate without introducing air bubbles by applying pressure.

[0070] The conditions for the conveying type laminator can be adjusted appropriately depending on the thickness of the resin layer of the laminated structure and the melt viscosity of the photosensitive resin composition at 50° C. and 100° C. For example, the conditions for the conveying type laminator are preferably a temperature of 50° C. to 80° C., a vacuum time of 10 to 60 seconds, and a pressure time of 20 to 120 seconds.

[0071] Next, exposure (irradiation with active energy rays) is performed from above the first film of the laminate structure. This process cures only the exposed resin layer. The exposure process is not particularly limited, and for example, it may be performed by a contact (or non-contact) method, selectively exposing to active energy rays through a photomask on which a desired pattern is formed, or it may be performed by a direct imaging device, exposing the desired pattern to active energy rays.

[0072] The exposure device used for actinic energy ray irradiation may be any device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, or the like, and capable of irradiating ultraviolet rays in the range of 350 to 450 nm. Furthermore, a direct imaging device (for example, a laser direct imaging device that draws an image directly with a laser based on CAD data from a computer) may also be used. The laser light source for the direct imaging device may be either a gas laser or a solid-state laser, as long as it uses laser light with a maximum wavelength in the range of 350 to 410 nm. The exposure dose for image formation varies depending on factors such as the film thickness, but is generally 20 to 800 mJ / cm. ２ , preferably 20 to 600 mJ / cm ２ The range may be:

[0073] After the exposure, the first film is peeled off from the laminated structure and developed to form a patterned resin layer on the substrate. When the first film is peeled off, the surface of the exposed and cured resin layer is imprinted with the shape of the surface of the first film.

[0074] The developing step is not particularly limited, and may be a dipping method, a shower method, a spray method, a brush method, etc. As the developer, an aqueous alkali solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, or an amine may be used.

[0075] The patterned resin layer is then cured by irradiation with active energy rays (light) or heat to form a cured product (cured coating). This process is called main curing or additional curing, and promotes polymerization of unreacted monomers in the resin layer, and furthermore, thermally cures the carboxyl group-containing photosensitive resin and the epoxy resin, thereby reducing the amount of remaining carboxyl groups. The active energy ray irradiation can be carried out in the same manner as the exposure described above, but is preferably carried out under conditions of stronger irradiation energy than that during exposure. For example, 500 to 3000 mJ / cm ２The thermal curing can be carried out under heating conditions of 100 to 200° C. for about 20 to 90 minutes. It is preferable that the main curing be carried out by thermal curing after photocuring.

[0076] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all by mass unless otherwise specified.

[0077] (Synthesis of alkali-soluble urethane resin A-1) In a 2 L flask equipped with a stirrer and a reflux condenser, 378.0 g of a bisphenol A type epoxy compound ("jER828" manufactured by Mitsubishi Chemical Corporation; bifunctional bisphenol A type epoxy resin, epoxy equivalent: 189 g / equivalent), 142.7 g of acrylic acid (molecular weight: 72.06), 2.94 g of 2,6-di-tert-butyl-p-cresol as a thermal polymerization inhibitor, and 1.53 g of triphenylphosphine as a reaction catalyst were charged, and the mixture was reacted at a temperature of 98 ° C. until the acid value of the reaction solution reached 0.5 mg KOH / g or less, yielding an epoxy acrylate compound (a) (theoretical molecular weight: 510.7). Next, 594.0 g of carbitol acetate as a reaction solvent and 105.5 g of dimethylolpropionic acid (b) (molecular weight: 134.16) were added to the reaction solution, and the temperature was raised to 45 ° C. To this solution, 264.7 g of isophorone diisocyanate (c) (molecular weight: 222.28) was gradually added dropwise so that the reaction temperature did not exceed 65° C. After the addition was completed, the temperature was raised to 80° C., and a peak at 2250 cm was observed by infrared absorption spectroscopy. －１ The reaction was continued for 6 hours until absorption by nearby isocyanate groups ceased, and then for a further 2 hours at 98°C. In this way, a resin solution (alkali-soluble urethane resin A-1) containing 60% by mass of alkali-soluble urethane resin (A) as a solid content was obtained. The acid value was measured and found to be 28.9 mgKOH / g (solid content acid value: 48.2 mgKOH / g).

[0078] (Synthesis of alkali-soluble urethane resin A-2) Into a reaction vessel equipped with a stirrer, a thermometer, and a condenser, 3600 g (4.5 mol) of a polycarbonate diol derived from 1,5-pentanediol and 1,6-hexanediol as a compound having two or more alcoholic hydroxyl groups ("TJ5650J" manufactured by Asahi Kasei Corporation, number average molecular weight 800), 814 g (5.5 mol) of dimethylolbutanoic acid, and 186 g (1.6 mol) of 2-hydroxyethyl acrylate as a molecular weight modifier (reaction terminator) were added. Next, 2009 g (10.8 mol) of trimethylhexamethylene diisocyanate as an isocyanate compound having no aromatic ring was added, and the mixture was heated to 60 ° C. with stirring and stopped. When the temperature in the reaction vessel began to decrease, the mixture was heated again and continued stirring at 80 ° C., and the absorption spectrum of the isocyanate group was measured by infrared absorption spectroscopy (2280 cm －１ The reaction was terminated after confirming that the carboxyl group-containing alkali-soluble urethane resin had disappeared. Carbitol acetate was then added so that the solids content was 60% by mass, yielding a viscous liquid carboxyl group-containing alkali-soluble urethane resin (alkali-soluble urethane resin A-2) containing a diluent. The acid value of the solids content of the resulting carboxyl group-containing alkali-soluble urethane resin A-2 was 49.8 mgKOH / g.

[0079] (Synthesis of Acid-Modified Epoxy Acrylate Resin A-3) 380 parts of bisphenol F epoxy resin (epoxy equivalent 950 g / eq, softening point 85°C) having an average degree of polymerization n of 6.2 and 925 parts of epichlorohydrin were dissolved in 462.5 parts of dimethyl sulfoxide, and then 60.9 parts of 98.5% NaOH was added over 100 minutes at 70°C with stirring. After the addition, the reaction was continued for another 3 hours at 70°C. After completion of the reaction, 250 parts of water was added and the mixture was washed with water. After oil-water separation, most of the dimethyl sulfoxide and excess unreacted epichlorohydrin were recovered from the oil layer by distillation under reduced pressure, and the remaining reaction product containing by-product salt and dimethyl sulfoxide was dissolved in 750 parts of methyl isobutyl ketone, to which 10 parts of 30% NaOH was added and the mixture was reacted for 1 hour at 70°C. After completion of the reaction, the mixture was washed twice with 200 parts of water. After oil-water separation, methyl isobutyl ketone was recovered by distillation from the oil layer to obtain epoxy resin (a) with an epoxy equivalent of 310 g / eq and a softening point of 69°C. Calculations based on the epoxy equivalent indicated that approximately 5 of the 6.2 alcoholic hydroxyl groups in the starting bisphenol F epoxy resin had been epoxidized in the resulting epoxy resin (a). 310 parts of this epoxy resin (a) and 282 parts of carbitol acetate were charged into a flask, heated to 90°C, stirred, and dissolved. The resulting solution was cooled to 60°C, and then 72 parts (1 mole) of acrylic acid, 0.5 parts of methylhydroquinone, and 2 parts of triphenylphosphine were added. The mixture was heated to 100°C and reacted for approximately 60 hours to obtain a reaction product with an acid value of 0.2 mgKOH / g. To this was added 140 parts (0.92 mol) of tetrahydrophthalic anhydride, and the mixture was heated to 90°C to carry out a reaction, thereby obtaining an acid-modified epoxy acrylate resin (acid-modified epoxy acrylate resin A-3). The resulting acid-modified epoxy acrylate resin A-3 had a solid content concentration of 62 mass% and an acid value of the solid content (mgKOH / g) of 100.

[0080] (Synthesis of Acid-Modified Epoxy Acrylate Resin A-4) 220 parts of a cresol novolac epoxy resin (EPICLON N-695 manufactured by DIC Corporation; epoxy equivalent: 220) was placed in a four-neck flask equipped with a stirrer and a reflux condenser, and 214 parts of carbitol acetate was added and dissolved by heating. Next, 0.1 parts of hydroquinone as a polymerization inhibitor and 2.0 parts of dimethylbenzylamine as a reaction catalyst were added. This mixture was heated to 95-105°C, and 72 parts of acrylic acid was slowly added dropwise, allowing the reaction to proceed for 16 hours. The reaction product was cooled to 80-90°C, and 106 parts of tetrahydrophthalic anhydride was added. The reaction was allowed to proceed for 8 hours, cooled, and then discharged. The acid-modified epoxy acrylate resin (Acid-Modified Epoxy Acrylate Resin A-4) thus obtained had a solids content of 65%, an acid value of the solids of 100 mgKOH / g, and a weight-average molecular weight Mw of approximately 3,500.

[0081] [Examples 1 to 3, Comparative Examples 1 to 3] <Preparation of Photosensitive Resin Compositions> The components shown in the Examples and Comparative Examples were blended according to the formulations shown in Table 1, premixed in a mixer, and then kneaded in a three-roll mill to prepare photosensitive resin compositions. Each value in the table indicates parts by mass (equivalent to solid content).

[0082]

[0083] The blend amounts in Table 1 are shown in parts by mass. Details of each component in Table 1 are as follows: *1: Trimethylolpropane EO-modified triacrylate, manufactured by Toagosei Co., Ltd., trade name Aronix M-350 *2: Caprolactone-modified hexaacrylate, manufactured by Nippon Kayaku Co., Ltd., trade name DPCA-60 *3: Special urethane acrylate, manufactured by Daicel Allnex Corporation, trade name RAYLOK5021 *4: 2,4,6-trimethylbenzoyldiphenylphosphine oxide *5: Biphenyl aralkyl epoxy resin, manufactured by Nippon Kayaku Co., Ltd., trade name NC-3000L *6: Aluminum hydroxide, manufactured by Showa Denko K.K., trade name Hijilite H-42M

[0084] <Laminate Structure Production 1> A 25 μm thick polyethylene terephthalate film ("E5041" manufactured by Toyobo Co., Ltd.) was prepared as the first film. Each photosensitive resin composition obtained above was uniformly applied to the surface of the first film using a die coater, and the film was dried by passing it through a drying oven at 80°C to 130°C (average 108°C) for 5 minutes to form a resin layer with a thickness of 100 μm. Next, a second film, MA-411 (manufactured by Oji F-Tex Co., Ltd., biaxially oriented polypropylene film), was laminated and bonded to the surface of the resin layer at normal pressure and 50°C, thereby obtaining laminate structures of Examples 1 to 3 and Comparative Examples 1 to 3, in which a resin layer was disposed between the first film and the second film. The obtained laminate structure was wound into a roll (winding length 50 m) and slit to a width of 247 mm to obtain a roll-shaped laminate structure.

[0085] <Evaluation of Photosensitive Resin Composition> (Melt Viscosity Measurement) After cutting the laminated structure obtained above to a predetermined size, the second film was peeled off, and the resin layer of the laminated structure was laminated onto a fluororesin (AGC Corporation, Aflex 50 HK NT) using a conveyor-type vacuum laminator (Nikko Materials Co., Ltd., CVP-300) under the conditions of lamination temperature = 60 ° C, vacuum time = 20 seconds, and pressure time = 30 seconds. The first film was then peeled off, and another resin layer was stacked and laminated. This process was repeated three times, resulting in a total thickness of the laminated resin layer of 400 μm. The melt viscosity was measured under the following measurement conditions using a Thermo Fisher Scientific RS-6000. The melt viscosities at 50 ° C and 100 ° C are shown in Table 2. (Melt viscosity measurement conditions) Sensor: Φ20 mm parallel plate type Heating rate: 5°C / min Measurement frequency: 1 Hz Measurement pressure: 3 Pa

[0086] <Evaluation 1 of Laminated Structure> (Lamination Properties in a Conveyor Laminator) The laminated structure obtained above was cut to a predetermined size, and the second film was then peeled off. Subsequently, lamination was performed by bringing the exposed surface of the resin layer into contact with a single-sided flexible printed wiring board (copper thickness = 70 μm, substrate (polyimide film) thickness = 25 μm) on which a circuit had been formed. Lamination was performed using a conveyor vacuum laminator (manufactured by Nikko Materials Co., Ltd., CVP-300) under the following conditions: lamination temperature = 60°C, vacuum time = 20 seconds, and pressure time = 30 seconds. The state after lamination was observed with an optical microscope and evaluated according to the following criteria. The evaluation results are shown in Table 2. [Evaluation Criteria] ○: No abnormalities (no voids due to poor embedding or bubbles due to air traps) ×: Abnormalities (voids due to poor embedding or bubbles due to air traps)

[0087] (Lamination properties in a vacuum roll laminator) The laminate structure obtained above was set in a vacuum roll laminator ("MVRN-DFW-500TP" manufactured by MCK Corporation). The lamination conditions were: degree of vacuum: 50 Pa, substrate tension: 50 N, substrate preheating temperature: 80°C, laminating roll temperature: 90°C, laminating pressure: 0.4 MPa, conveying speed: 0.5 m / min, dry film unwinding tension: 20 N, separator winding tension: 15 N. While conveying the laminate structure, the second film was peeled off, and lamination was performed so that the surface with the exposed resin layer was in contact with a single-sided flexible printed wiring board (copper thickness = 70 μm, substrate (polyimide film) thickness = 25 μm) on which a circuit was formed. The state after lamination was observed with an optical microscope and evaluated according to the following criteria. The evaluation results are shown in Table 2. Evaluation was performed according to the following criteria. The evaluation results are shown in Table 2. [Evaluation criteria] ○: No abnormalities (no voids due to poor filling or bubbles due to air traps) ×: Abnormalities (voids due to poor filling or bubbles due to air traps)

[0088] As is clear from Table 2, the laminate structures of Examples 1 to 3 exhibit good lamination properties with both a conveyor-type laminator and a vacuum roll laminator, whereas when the melt viscosity is too low as in Comparative Example 1, fusion occurs before a predetermined degree of vacuum is reached, resulting in a state in which air is trapped (so-called air traps), resulting in poor lamination. Furthermore, lamination using a vacuum roll laminator was attempted for Comparative Example 1, but the peelability of the second film deteriorated due to the melt viscosity being too low, making lamination impossible and therefore evaluation was not possible.

[0089]

[0090] [Examples 4 to 6, Comparative Examples 4 to 5] <Production of laminated structure 2> Subsequently, laminated structures having different film thicknesses were produced in the same manner as in <Production of laminated structure 1> above, except that resin layers having film thicknesses shown in Table 3 below were formed using the photosensitive composition of Example 1, the photosensitive composition of Comparative Example 1, and the photosensitive composition of Comparative Example 3.

[0091]

[0092] <Evaluation 2 of laminated structure> The obtained laminated structure was evaluated for lamination properties in the same manner as in the above <Evaluation 1 of laminated structure>. The results are shown in Table 4. In Comparative Example 4, the second film could not be peeled off, and evaluation of lamination properties was impossible.

[0093]

[0094] REFERENCE SIGNS LIST 1 laminated structure 10 first film 20 resin layer 30 second film

Claims

1. A laminated structure comprising a first film and a resin layer formed on the first film, the resin layer is made of a dried coating film of a photosensitive resin composition, the resin layer has a melt viscosity at 50°C of 1,000 Pa s or more and 50,000 Pa s or less, and a melt viscosity at 100°C of 50 Pa s or more and 2,000 Pa s or less; A laminated structure, characterized in that the resin layer has a film thickness of more than 80 μm and not more than 300 μm.

2. 2. The laminate structure according to claim 1, wherein the resin layer has a melt viscosity at 50°C of 3,000 Pa·s or more and 40,000 Pa·s or less, and a melt viscosity at 100°C of 100 Pa·s or more and 1,500 Pa·s or less.

3. 2. The laminate structure according to claim 1, wherein the ratio of the melt viscosity at 50°C to the melt viscosity at 100°C of the resin layer is 10 or more and 200 or less.

4. The laminate structure according to claim 1 , wherein the photosensitive resin composition comprises (A) a curable resin, (B) a photopolymerization initiator, and (C) an inorganic filler.

5. The laminate structure of claim 1 , further comprising a second film on the resin layer.

6. 10. The laminate structure of claim 1, adapted for lamination in both a conveyor laminator and a vacuum roll laminator.

7. A cured product obtained by curing the resin layer of the laminate structure according to any one of claims 1 to 6.

8. A printed wiring board comprising the cured product according to claim 7.