Photosensitive resin composition, photosensitive element, method for forming resist pattern, and method for producing printed wiring board

Abstract

A photosensitive resin composition according to one aspect of the present disclosure contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the binder polymer has a structural unit derived from acrylic acid, and the sensitizer content is less than 0.01 parts by mass relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

Description

Photosensitive resin composition, photosensitive element, method for forming resist pattern, and method for manufacturing printed wiring board

[0001] The present disclosure relates to a photosensitive resin composition, a photosensitive element, a method for forming a resist pattern, and a method for producing a printed wiring board.

[0002] In the field of printed wiring board manufacturing, photosensitive resin compositions and photosensitive elements comprising a support and a layer formed on the support using the photosensitive resin composition (hereinafter also referred to as a "photosensitive layer") are widely used as resist materials used in etching or plating processes (see, for example, Patent Documents 1 and 2 listed below).

[0003] A printed wiring board is manufactured, for example, using the above-mentioned photosensitive element by the following procedure. First, the photosensitive layer of the photosensitive element is laminated onto a circuit-forming substrate such as a copper-clad laminate. Next, predetermined portions of the photosensitive layer are exposed through a photomask to form photocured portions. At this time, the support is peeled off before or after exposure. Thereafter, areas of the photosensitive layer other than the photocured portions are removed with a developer to form a resist pattern on the substrate. Next, using the resist pattern as a resist, an etching process or a plating process is performed to form a conductor pattern (conductor layer) on the substrate, and finally the resist is peeled off and removed.

[0004] JP 2009-003177 A JP 2013-061556 A

[0005] In recent years, in electronic components such as inductors, increasing the thickness of the conductor layer to form a wiring pattern with a high aspect ratio has been considered. Therefore, a photosensitive resin composition capable of forming a thick-film resist pattern (e.g., a film thickness of 30 μm or more) is desired. However, with conventional photosensitive resin compositions, increasing the thickness of the photosensitive layer makes it difficult for light to penetrate to the bottom of the photosensitive layer, resulting in reduced adhesion and making it difficult to form a resist pattern with a high aspect ratio. Furthermore, increasing the thickness of the photosensitive layer tends to increase the development time and stripping time. In order to shorten the development time and stripping time and increase production efficiency, a photosensitive resin composition with excellent developability and stripping properties is desired.

[0006] An object of the present disclosure is to provide a photosensitive resin composition and a photosensitive element that are excellent in developability and removability and are capable of forming a resist pattern with a high aspect ratio, as well as a method for forming a resist pattern and a method for producing a printed wiring board using the same.

[0007] To achieve the above object, one aspect of the present disclosure relates to the following photosensitive resin composition, photosensitive element, method for forming a resist pattern, and method for manufacturing a printed wiring board. [1] A photosensitive resin composition containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the binder polymer has a structural unit derived from acrylic acid, and the content of the sensitizer is less than 0.01 parts by mass per 100 parts by mass of the binder polymer and the photopolymerizable compound. [2] The photosensitive resin composition according to [1] above, wherein the content of the sensitizer is 0.65 parts by mass or less per 100 parts by mass of the photopolymerization initiator. [3] The photosensitive resin composition according to [1] or [2] above, wherein the content of the sensitizer is 0.001 parts by mass or more per 100 parts by mass of the binder polymer and the photopolymerizable compound. [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the binder polymer further contains at least one structural unit selected from the group consisting of a structural unit derived from styrene or a styrene derivative and a structural unit derived from a (meth)acrylate compound having an alicyclic structure. [5] The photosensitive resin composition according to any one of [1] to [4] above, wherein the sensitizer contains at least one structural unit selected from the group consisting of a dialkylaminobenzophenone compound, a pyrazoline compound, and an anthracene compound. [6] A photosensitive element comprising a support and a photosensitive layer formed on the support using the photosensitive resin composition according to any one of [1] to [5] above. [7] The photosensitive element according to [6] above, wherein the photosensitive layer has a thickness of 30 μm or more. [8] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition described in any one of [1] to [5] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing from the substrate the unphotocured portions of the photosensitive layer to form a resist pattern. [9] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element described in [6] or [7] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing from the substrate the unphotocured portions of the photosensitive layer to form a resist pattern.

[10] A method for producing a printed wiring board, comprising a step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to [8] or [9] above, to form a conductor pattern.

[0008] According to the present disclosure, it is possible to provide a photosensitive resin composition and a photosensitive element that are excellent in developability and removability and that can form a resist pattern with a high aspect ratio, as well as a method for forming a resist pattern and a method for producing a printed wiring board using the same.

[0009] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a photosensitive element.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail, but the present invention is not limited to the following embodiments.

[0011] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved. The term "layer" encompasses not only a structure that is formed over the entire surface when observed in a plan view, but also a structure that is formed on a portion of the surface. Numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples.

[0012] In this specification, "(meth)acrylate" means at least one of "acrylate" and its corresponding "methacrylate." The same applies to other similar expressions such as (meth)acryloyl.

[0013] In this specification, the amount of each component in a photosensitive resin composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. In this specification, the term "solid content" refers to the non-volatile content of the photosensitive resin composition excluding volatile substances (water, solvent, etc.). In other words, the term "solid content" refers to components other than the solvent that remain without volatilizing upon drying of the photosensitive resin composition, as described below, and includes components that are liquid, syrup-like, or waxy at room temperature (25°C).

[0014] [Photosensitive Resin Composition] The photosensitive resin composition according to this embodiment contains (A) a binder polymer (hereinafter sometimes referred to as "component (A)"), (B) a photopolymerizable compound (hereinafter sometimes referred to as "component (B)"), (C) a photopolymerization initiator (hereinafter sometimes referred to as "component (C)"), and (D) a sensitizer (hereinafter sometimes referred to as "component (D)"). The component (A) has a structural unit derived from acrylic acid, and the content of the component (D) is less than 0.01 parts by mass per 100 parts by mass of the total of the components (A) and (B). The photosensitive resin composition according to this embodiment uses such a specific binder polymer in combination with a specific amount of the sensitizer, thereby enabling the formation of a resist pattern with excellent developability and removability and a high aspect ratio, making it suitable for use in thick film applications. Each component that may be contained in the photosensitive resin composition will be described in detail below.

[0015] Component (A): Binder Polymer The photosensitive resin composition contains one or more components (A). Component (A) has a structural unit derived from acrylic acid (hereinafter, sometimes referred to as a "first structural unit"). Component (A) can be produced by radical polymerization of a polymerizable monomer containing acrylic acid.

[0016] The photosensitive resin composition according to this embodiment contains a binder polymer having a first structural unit as component (A), thereby improving the developability and post-curing releasability of the photosensitive layer formed from the photosensitive resin composition. Acrylic acid has a lower glass transition temperature and is softer than methacrylic acid. The inventors have found that using acrylic acid as a polymerizable monomer can lower the glass transition temperature of the resulting binder polymer, thereby improving the developability and releasability of the photosensitive resin composition.

[0017] The content of the first structural unit in the component (A) may be 15% by mass or more, 18% by mass or more, 19% by mass or more, or 20% by mass or more, based on the total mass of structural units derived from polymerizable monomers constituting the binder polymer, from the viewpoints of sensitivity, developability, adhesion, and releasability, and may be 27% by mass or less, 26% by mass or less, 25% by mass or less, or 24% by mass or less, from the viewpoint of alkali resistance. The content of the first structural unit in the component (A) may be 15% by mass to 27% by mass, 18% by mass to 26% by mass, 19% by mass to 25% by mass, or 20% by mass to 24% by mass, based on the total mass of structural units derived from polymerizable monomers constituting the binder polymer.

[0018] From the viewpoint of improving the resolution and adhesion of the photosensitive resin composition and reducing the amount of resist tail generation, the component (A) may have a structural unit derived from styrene or a styrene derivative (hereinafter, sometimes referred to as a "second structural unit.") Examples of styrene derivatives include vinyltoluene, α-methylstyrene, p-methylstyrene, and p-ethylstyrene.

[0019] The content of the second structural unit in the component (A) may be 55% by mass or more, 60% by mass or more, or 65% by mass or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer, from the viewpoint of improving resolution and adhesion and reducing the amount of resist tail generation; and may be 84% by mass or less, 80% by mass or less, 78% by mass or less, or 75% by mass or less, from the viewpoint of appropriately shortening the development time and making it less likely that undeveloped images will remain.

[0020] From the viewpoint of the resolution and adhesion of the photosensitive resin composition, the component (A) may have a structural unit derived from a (meth)acrylate compound having an alicyclic structure (hereinafter, sometimes referred to as a "third structural unit.") Examples of the (meth)acrylate having an alicyclic structure include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclopentanyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0021] The content of the third structural unit in the component (A) may be 0.5% by mass or more, 0.8% by mass or more, 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, or 4.0% by mass or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer, from the viewpoint of further improving the resolution and adhesion of the photosensitive resin composition, and may be 20% by mass or less, 18% by mass or less, 16% by mass or less, 14% by mass or less, or 12% by mass or less, from the viewpoint of further improving the developability of the photosensitive resin composition.

[0022] The component (A) may further have a structural unit derived from a polymerizable monomer other than those described above (hereinafter also referred to as "other monomer"). Examples of other monomers include methacrylic acid, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, benzyl (meth)acrylate or a derivative thereof, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, β-furyl (meth)acrylic acid, β-styryl (meth)acrylic acid, maleic acid, maleic anhydride, maleic acid monoalkyl ester, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. These may be used alone or in combination of two or more.

[0023] The weight average molecular weight (Mw) of component (A) may be 20,000 or more, 25,000 or more, 30,000 or more, or 35,000 or more, or may be 80,000 or less, 70,000 or less, 60,000 or less, or 50,000 or less. The Mw of component (A) may be 20,000 to 80,000, 25,000 to 70,000, 30,000 to 60,000, or 35,000 to 50,000. When the Mw is 80,000 or less, resolution and developability tend to be further improved, while when the Mw is 20,000 or more, the flexibility of the cured film is improved, and chipping and peeling of the resist pattern tend to be less likely to occur.

[0024] The Mw can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. More specifically, it can be measured under the conditions described in the Examples.

[0025] The acid value of component (A) may be 140 mgKOH / g or more, 150 mgKOH / g or more, 160 mgKOH / g or more, or 170 mgKOH / g or more, or may be 200 mgKOH / g or less, 190 mgKOH / g or less, 185 mgKOH / g or less, or 180 mgKOH / g or less. From the viewpoint of better developability and strippability, the acid value of component (A) may be 140 to 200 mgKOH / g, 150 to 190 mgKOH / g, 160 to 185 mgKOH / g, or 170 to 180 mgKOH / g. When the acid value of component (A) is 140 mgKOH / g or more, it is possible to more sufficiently prevent the development time from becoming long, and when the acid value is 200 mgKOH / g or less, it is easier to further improve the developer resistance (adhesion) of the cured product of the photosensitive resin composition. The acid value of component (A) can be adjusted by adjusting the structural unit derived from acrylic acid, and can be measured in accordance with JIS K6901:2008 5.3.2.

[0026] The glass transition temperature (Tg) of component (A) may be 80°C or higher, 90°C or higher, 95°C or higher, or 100°C or higher, or may be 113°C or lower, 112°C or lower, 111°C or lower, or 110°C or lower. The Tg of component (A) may be 80°C to 113°C, 90°C to 112°C, 95°C to 111°C, or 100°C to 110°C. A Tg of component (A) of 80°C or higher facilitates improved lamination of the photosensitive layer formed from the photosensitive resin composition, while a Tg of 120°C or lower facilitates improved adhesion, resolution, and storage stability of the photosensitive resin composition. The Tg of component (A) is a value determined according to Fox's formula and can be calculated from the mass of each polymerizable monomer constituting component (A) and the Tg of the homopolymer of each polymerizable monomer.

[0027] The content of the (A) component may be 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, or 50 parts by mass or more, relative to 100 parts by mass of the total amount of the (A) component and the (B) component, from the viewpoint of excellent film formability, and may be 80 parts by mass or less, 70 parts by mass or less, or 60 parts by mass or less, from the viewpoint of further improving sensitivity and resolution.

[0028] Component (B): Photopolymerizable Compound The photosensitive resin composition contains one or more types of component (B). Component (B) may be any compound that polymerizes when exposed to light, such as a compound having an ethylenically unsaturated bond. Component (B) may contain a polyfunctional monomer having two or more reactive groups that react with radicals. From the viewpoints of developability, resolution, and releasability after curing, component (B) may contain a bisphenol A (meth)acrylate compound.

[0029] Examples of bisphenol A type (meth)acrylate compounds include 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolypropoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolybutoxy)phenyl)propane, and 2,2-bis(4-((meth)acryloxypolyethoxypolypropoxy)phenyl)propane. From the viewpoints of resolution and strippability, component (B) may contain 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane. As the 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane, a compound having 10 or more oxyethylene groups may be used, or a compound having less than 10 oxyethylene groups may be used, or a compound having 10 or more oxyethylene groups may be used in combination with a compound having less than 10 oxyethylene groups. Examples of 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane include 2,2-bis(4-((meth)acryloxypentaethoxy)phenyl)propane and 2,2-bis(4-((meth)acryloxydiethoxy)phenyl)propane.

[0030] From the viewpoint of resolution, the content of the bisphenol A type (meth)acrylate compound may be 20% by mass or more, 40% by mass or more, 60% by mass or more, or 80% by mass or more, and may be 100% by mass or less, or 95% by mass or less, based on the total amount of component (B). When 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is used as the bisphenol A type (meth)acrylate compound, the content of the compound having 10 or more oxyethylene groups may be 20% by mass or more, 40% by mass or more, 60% by mass or more, or 70% by mass or more, and may be 100% by mass or less, 95% by mass or less, or 90% by mass or less, based on the total amount of component (B).

[0031] From the viewpoint of resolution and flexibility, component (B) may contain an α,β-unsaturated ester compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid. Examples of the α,β-unsaturated ester compound include polyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and EO-modified polypropylene glycol, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO-PO-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate.

[0032] From the viewpoint of sensitivity and adhesion, the component (B) may contain a compound having three or more (meth)acryloyl groups. Examples of the compound having three or more (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO-PO-modified trimethylolpropane tri(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, EO-modified ditrimethylolpropane tetra(meth)acrylate, and EO-modified dipentaerythritol hexa(meth)acrylate.

[0033] The content of the α,β-unsaturated ester compound may be 20% by mass or more or 30% by mass or more based on the total amount of the component (B) from the viewpoint of flexibility, and may be 70% by mass or less or 60% by mass or less from the viewpoint of resolution.

[0034] The photosensitive resin composition may contain, as component (B), a photopolymerizable compound other than the bisphenol A (meth)acrylate compound and the α,β-unsaturated ester compound.

[0035] Examples of other photopolymerizable compounds include nonylphenoxy polyethyleneoxy acrylate, phthalic acid compounds, (meth)acrylic acid alkyl esters, and photopolymerizable compounds having at least one cationically polymerizable cyclic ether group in the molecule (such as oxetane compounds). From the viewpoints of resolution, adhesion, resist shape, and releasability after curing, the other photopolymerizable compound may be at least one selected from the group consisting of nonylphenoxy polyethyleneoxy acrylate and phthalic acid compounds.

[0036] Examples of nonylphenoxy polyethyleneoxyacrylates include nonylphenoxytriethyleneoxyacrylate, nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate, nonylphenoxynonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, and nonylphenoxyundecaethyleneoxyacrylate.

[0037] Examples of phthalic acid compounds include γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate (also known as 3-chloro-2-hydroxypropyl-2-(meth)acryloyloxyethyl phthalate), β-hydroxyethyl-β'-(meth)acryloyloxyethyl-o-phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate.

[0038] When the component (B) contains other photopolymerizable compounds, the content of the other photopolymerizable compounds may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, and may be 30% by mass or less, 25% by mass or less, or 20% by mass or less, based on the total amount of the component (B), from the viewpoints of resolution, adhesion, resist shape, and releasability after curing.

[0039] From the viewpoints of adhesion and resolution, the component (B) may include, among the above-mentioned compounds, a compound having a total of 2 to 40 oxyethylene groups (EO groups) and / or oxypropylene groups (PO groups) in the molecule. From the viewpoints of adhesion and resolution, the total number of EO groups and / or PO groups may be 2 to 40 or 2 to 30.

[0040] The content of the compound having a total of 2 to 40 EO groups and / or PO groups may be 2 to 15 mass%, 4 to 12 mass%, or 5 to 8 mass%, based on the total amount of component (B), from the viewpoints of adhesion and resolution.

[0041] The content of the component (B) may be 3% by mass or more, 10% by mass or more, or 25% by mass or more, based on the total solid content of the photosensitive resin composition, from the viewpoint of sensitivity and resolution, and may be 70% by mass or less, 60% by mass or less, or 50% by mass or less, from the viewpoint of film formability.

[0042] Component (C): Photopolymerization Initiator The photosensitive resin composition contains one or more types of component (C). The component (C) is not particularly limited as long as it is a component that can polymerize component (B), and can be appropriately selected from commonly used photopolymerization initiators.

[0043] Examples of the component (C) include hexaarylbiimidazole compounds; aromatic ketone compounds such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanone-1; alkyl aryl ketone compounds such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone; benzoin ether compounds such as benzoin alkyl ether; benzoin compounds such as benzoin and alkylbenzoin; benzyl derivatives such as benzyl dimethyl ketal; and phosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethylbenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0044] From the viewpoint of suppressing penetration of the photosensitizer into the polyethylene film, component (C) may contain a hexaarylbiimidazole compound. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. The hydrogen atom bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (e.g., a chlorine atom).

[0045] The hexaarylbiimidazole compound may be a 2,4,5-triarylimidazole dimer. Examples of the 2,4,5-triarylimidazole dimer include 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-bis-(m-methoxyphenyl)imidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer. From the viewpoint of further suppressing the penetration of the photosensitizer into the polyethylene film, the hexaarylbiimidazole compound is preferably 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, and more preferably 2,2-bis(o-chlorophenyl)-4,5-4',5'-tetraphenyl-1,2'biimidazole.

[0046] The content of the hexaarylbiimidazole compound may be 90% by mass or more, 95% by mass or more, or 99% by mass or more, based on the total amount of component (C). Component (C) may consist solely of the hexaarylbiimidazole compound.

[0047] From the viewpoints of sensitivity and adhesion, the content of the component (C) may be 0.1 mass % or more, 0.5 mass % or more, or 1.0 mass % or more, and may be 20 mass % or less, 10 mass % or less, or 5 mass % or less, based on the total solid content of the photosensitive resin composition.

[0048] Component (D): Sensitizer The photosensitive resin composition contains one or more types of component (D). Examples of component (D) include dialkylaminobenzophenone compounds, pyrazoline compounds, anthracene compounds, coumarin compounds, xanthone compounds, thioxanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, naphthalimide compounds, triarylamine compounds, and aminoacridine compounds.

[0049] Examples of dialkylaminobenzophenone compounds include 4,4'-bis(dimethylamino)benzophenone and 4,4'-bis(diethylamino)benzophenone.

[0050] Examples of the pyrazoline compound include 1-(4-methoxyphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1,5-bis-(4-methoxyphenyl)-3-(4-methoxystyryl)-pyrazoline, 1-(4-isopropylphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, 1,5-bis-(4-isopropylphenyl)-3-(4- isopropylstyryl)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-isopropyl-styryl)-5-(4-isopropyl 1-(4-methoxyphenyl)-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-phenyl-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,6-dimethoxystyryl)-5 -(2,6-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,4-dimethoxystyryl)-5-(2 ,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,5-dimethoxystyryl)-5 -(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,4-dimethoxystyryl)-5- (3,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, and 1-(4-isopropyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline.

[0051] Examples of the anthracene compound include 1-methylanthracene, 2-methylanthracene, 9-methylanthracene, 2-ethylanthracene, 2-butylanthracene, 9-vinylanthracene, 9-phenylanthracene, 1-aminoanthracene, 2-aminoanthracene, 9-(methylaminomethyl)anthracene, 9-acetylanthracene, 9-anthraldehyde, 9,10-dimethylanthracene, 9,10-dimethoxyanthracene, and 9,10- Examples include diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-dipentoxyanthracene, 9,10-di(2-ethylhexyloxy)anthracene, 9,10-diphenylanthracene, 2-bromo-9,10-diphenylanthracene, 9-(4-bromophenyl)-10-phenylanthracene, 10-methyl-9-anthraldehyde, and 1,4,9,10-tetrahydroxyanthracene.

[0052] Examples of coumarin compounds include 3-benzoyl-7-diethylaminocoumarin, 7-diethylamino-4-methylcoumarin, and 3,3'-carbonylbis(7-diethylaminocoumarin).

[0053] From the viewpoints of adhesion, resolution, and a high aspect ratio, the component (D) may contain at least one compound selected from the group consisting of a dialkylaminobenzophenone compound, a pyrazoline compound, and an anthracene compound.

[0054] From the viewpoints of adhesion, resolution, and a high aspect ratio, the content of the component (D) may be less than 0.01 parts by mass, 0.009 parts by mass or less, 0.008 parts by mass or less, 0.007 parts by mass or less, or 0.006 parts by mass or less, relative to 100 parts by mass of the total amount of the components (A) and (B). From the viewpoint of sensitivity, the content of the component (D) may be 0.001 parts by mass or more, 0.002 parts by mass or more, 0.003 parts by mass or more, or 0.004 parts by mass or more, relative to 100 parts by mass of the total amount of the components (A) and (B).

[0055] From the viewpoints of adhesion, resolution, and a high aspect ratio, the content of the component (D) may be 0.65 parts by mass or less, 0.60 parts by mass or less, 0.50 parts by mass or less, 0.40 parts by mass or less, 0.30 parts by mass or less, or 0.20 parts by mass or less, relative to 100 parts by mass of the total amount of the component (C).

[0056] Component (E): Polymerization Inhibitor The photosensitive resin composition may further contain a polymerization inhibitor (component (E)) from the viewpoint of suppressing polymerization in unexposed areas during resist pattern formation and improving resolution. Examples of the polymerization inhibitor include 4-tert-butylcatechol and 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl.

[0057] The content of component (E) may be 0.001 to 0.10 parts by mass, 0.005 to 0.08 parts by mass, or 0.01 to 0.06 parts by mass, relative to 100 parts by mass of the total amount of components (A) and (B).

[0058] The photosensitive resin composition may further contain one or more other components in addition to the components described above. Examples of such other components include hydrogen donors (such as bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leuco crystal violet, and N-phenylglycine), dyes (such as malachite green), photocoloring agents (such as tribromophenyl sulfone and leuco crystal violet), thermal color-developing inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, defoamers, flame retardants, stabilizers, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, and thermal crosslinkers. The content of such other components may be 0.005 parts by mass or more, or 0.01 parts by mass or more, and may be 20 parts by mass or less, per 100 parts by mass of the total amount of component (A) and component (B).

[0059] The photosensitive resin composition may further contain one or more organic solvents from the viewpoint of adjusting the viscosity. Examples of organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, and propylene glycol monomethyl ether. The content of the organic solvent may be 40% by mass or more and 70% by mass or less, based on the total amount of the photosensitive resin composition.

[0060] The photosensitive resin composition can be suitably used for forming a resist pattern, and can be particularly suitably used in the method for producing a wiring board described below.

[0061] [Photosensitive Element] The photosensitive element according to this embodiment comprises a support and a photosensitive layer formed on the support using the photosensitive resin composition. When using the photosensitive element according to this embodiment, the photosensitive layer may be laminated on a substrate and then exposed without peeling off the support. Figure 1 is a schematic cross-sectional view of a photosensitive element according to one embodiment. As shown in Figure 1, the photosensitive element 1 comprises a support 2 and a photosensitive layer 3 derived from the photosensitive resin composition formed on the support 2, and is configured to comprise other layers such as a protective layer 4 that are provided as needed.

[0062] The support 2 and the protective layer 4 may each be a polymer film having heat resistance and solvent resistance, for example, a polyester film such as a polyethylene terephthalate film, a polyethylene film, a polyolefin film such as a polypropylene film, etc. The support 2 and the protective layer 4 may each be a film of a hydrocarbon polymer other than polyolefin. A film of a hydrocarbon polymer including polyolefin may have a low density, for example, a density of 1.014 g / cm ３ The support 2 and the protective layer 4 may each be a stretched film obtained by stretching the low-density hydrocarbon-based polymer film. The type of polymer film constituting the protective layer 4 may be the same as or different from the type of polymer film constituting the support 2.

[0063] These polymer films are commercially available as polyethylene terephthalate films such as the PS series (e.g., PS-25) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by Tamapoly Co., Ltd., or polypropylene films manufactured by Oji Paper Co., Ltd. (e.g., Alphan MA-410, E-200C) and Shin-Etsu Film Co., Ltd.

[0064] The thickness of the support 2 may be 1 μm or more or 5 μm or more from the viewpoint of preventing damage to the support 2 when peeling the support 2 from the photosensitive layer 3, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of enabling suitable exposure even when exposure is performed through the support 2.

[0065] The thickness of the protective layer 4 may be 1 μm or more, 5 μm or more, or 15 μm or more from the viewpoint of suppressing damage to the protective layer 4 when the photosensitive layer 3 and the support 2 are laminated onto the substrate while peeling off the protective layer 4, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improving productivity.

[0066] The photosensitive layer 3 is formed using the above-described photosensitive resin composition. The thickness of the photosensitive layer 3 after drying (after volatilizing the organic solvent if the photosensitive resin composition contains an organic solvent) may be 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, or 80 μm or more from the viewpoint of forming a thick resist pattern, and may be 500 μm or less, 450 μm or less, 400 μm or less, 350 μm or less, or 300 μm or less from the viewpoints of adhesion, resolution, and a high aspect ratio.

[0067] The photosensitive element 1 can be obtained, for example, as follows. First, a photosensitive layer 3 is formed on a support 2. The photosensitive layer 3 can be formed, for example, by applying a photosensitive resin composition containing an organic solvent to form a coating layer and drying the coating layer. Next, a protective layer 4 is formed on the surface of the photosensitive layer 3 opposite the support 2.

[0068] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating, etc. The coating layer is dried so that the amount of organic solvent remaining in the photosensitive layer 3 is, for example, 2% by mass or less, and specifically, for example, at 70 to 150°C for about 5 to 30 minutes.

[0069] In another embodiment, the photosensitive element may not include a protective layer, and may further include other layers such as a cushion layer, an adhesive layer, a light-absorbing layer, and a gas barrier layer.

[0070] The photosensitive element 1 may be, for example, in the form of a sheet, or may be in the form of a photosensitive element roll wound around a core. In the photosensitive element roll, the photosensitive element 1 is preferably wound with the support 2 facing outward. The core is formed of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or the like. An end separator may be provided on the end face of the photosensitive element roll from the viewpoint of end face protection, and a moisture-proof end face separator may be provided from the viewpoint of edge fusion resistance. The photosensitive element 1 may be wrapped, for example, in a black sheet with low moisture permeability.

[0071] The photosensitive element 1 can be suitably used for forming a resist pattern, and can be particularly suitably used in the method for producing a printed wiring board, which will be described later.

[0072] [Method of Forming a Resist Pattern] The method of forming a resist pattern according to this embodiment includes the steps of forming a photosensitive layer on a substrate using the photosensitive resin composition or the photosensitive element (photosensitive layer formation step), irradiating at least a portion (predetermined portion) of the photosensitive layer with actinic light to form a photocured portion (exposure step), and removing at least a portion of the unphotocured portion of the photosensitive layer from the substrate (development step), and may include other steps as necessary. The resist pattern can also be referred to as a photocured product pattern of the photosensitive resin composition or a relief pattern. The method of forming a resist pattern can also be referred to as a method of manufacturing a substrate with a resist pattern.

[0073] (Photosensitive layer forming process) As a method for forming a photosensitive layer on a substrate, for example, the photosensitive resin composition may be applied and dried, or after removing the protective layer from the photosensitive element, the photosensitive layer of the photosensitive element may be pressed onto the substrate while heating. When a photosensitive element is used, a laminate is obtained in which the substrate, the photosensitive layer, and the support are laminated in this order. The substrate is not particularly limited, but usually, a circuit-forming substrate having an insulating layer and a conductor layer formed on the insulating layer, or a die pad (substrate for lead frame) such as an alloy substrate is used.

[0074] When a photosensitive element is used, the photosensitive layer forming step may be carried out under reduced pressure from the viewpoint of adhesion and followability. The photosensitive layer and / or the substrate may be heated at a temperature of 70 to 130°C during pressure bonding. The pressure bonding is carried out at a pressure of about 0.1 to 1.0 MPa (1 to 10 kgf / cm). ２ These conditions may be appropriately selected as required. Note that if the photosensitive layer is heated to 70 to 130°C, it is not necessary to preheat the substrate, but in order to further improve adhesion and conformability, it is also possible to preheat the substrate.

[0075] (Exposure process) In the exposure process, at least a part of the photosensitive layer formed on the substrate is irradiated with actinic rays, whereby the part irradiated with actinic rays is photocured to form a latent image. In this case, if a support is present on the photosensitive layer, and the support is transparent to actinic rays, the actinic rays can be irradiated through the support, but if the support is light-shielding, the support is removed before the photosensitive layer is irradiated with actinic rays.

[0076] Examples of the exposure method include a method of irradiating an actinic ray in an imagewise manner by a direct writing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method, a method of irradiating an actinic ray in an imagewise manner through a negative or positive mask pattern called artwork (a mask exposure method), and a method of irradiating an actinic ray in an imagewise manner by a projection exposure method.

[0077] As the light source of the actinic rays, a known light source can be used, for example, a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid-state laser such as a YAG laser, a semiconductor laser, or the like, which effectively emits ultraviolet light or visible light.

[0078] (Developing Step) In the developing step, at least a portion of the uncured portion (other than the cured portion) of the photosensitive layer is removed from the substrate, thereby forming a resist pattern on the substrate.

[0079] When a support is present on the photosensitive layer, the support is removed, and then the areas other than the photocured areas (which can also be called unexposed areas) are removed (developed). There are two development methods, wet development and dry development, but wet development is widely used.

[0080] When wet development is employed, development may be carried out by a known development method using a developer suitable for the photosensitive resin composition. Examples of the development method include a dipping method, a puddling method, a spraying method, brushing, slapping, scrubbing, and swinging immersion. From the viewpoint of resolution, a high-pressure spraying method may be used as the development method. Development may be carried out by combining two or more of these methods.

[0081] The composition of the developer is appropriately selected depending on the composition of the photosensitive resin composition. Examples of the developer include an alkaline aqueous solution and an organic solvent developer.

[0082] From the viewpoints of safety, stability, and ease of use, an alkaline aqueous solution may be used as the developer. Examples of the base for the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide; alkali carbonates such as carbonates or bicarbonates of lithium, sodium, potassium, or ammonium; alkali metal phosphates such as potassium phosphate and sodium phosphate; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol, 1,3-diaminopropanol-2, and morpholine.

[0083] Examples of alkaline aqueous solutions that can be used for development include a dilute solution of 0.1 to 5% by mass sodium carbonate, a dilute solution of 0.1 to 5% by mass potassium carbonate, a dilute solution of 0.1 to 5% by mass sodium hydroxide, and a dilute solution of 0.1 to 5% by mass sodium tetraborate. The pH of the alkaline aqueous solution may be in the range of 9 to 11, and the temperature can be adjusted according to the alkaline developability of the photosensitive layer. The alkaline aqueous solution may contain, for example, a surfactant, an antifoaming agent, or a small amount of an organic solvent to promote development.

[0084] Examples of organic solvents used in the alkaline aqueous solution include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0085] Examples of organic solvents used in the organic solvent developer include 1,1,1-trichloroethane, N-methyl-2-pyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. To prevent ignition, water may be added to these organic solvents in an amount of 1 to 20% by mass to form an organic solvent developer.

[0086] In the method for forming a resist pattern according to this embodiment, after removing the uncured portion in the development step, the resist is heated at about 60 to 250° C. or irradiated with 0.2 to 10 J / cm 2 as needed. ２ The method may further include a step of further hardening the resist pattern by exposing the resist pattern to light.

[0087] [Method for manufacturing printed wiring board] The method for manufacturing a printed wiring board according to this embodiment includes a step of forming a conductor pattern by etching or plating a substrate on which a resist pattern has been formed by the above-described method for forming a resist pattern, and may also include other steps such as a resist pattern removal step, as necessary.

[0088] In the plating process, a conductive layer provided on a substrate is plated using a resist pattern formed on the substrate as a mask. After the plating process, the resist may be removed by removing the resist pattern as described below, and the conductive layer covered by the resist may be etched to form a conductive pattern. The plating method may be electrolytic plating or electroless plating, or may be electroless plating.

[0089] On the other hand, in the etching process, a conductive layer provided on a substrate is etched away using a resist pattern formed on the substrate as a mask to form a conductive pattern. The etching method is appropriately selected depending on the conductive layer to be removed. Examples of etching solutions include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide-based etching solution.

[0090] After the etching or plating process, the resist pattern on the substrate may be removed. The resist pattern can be removed, for example, with an aqueous solution that is more strongly alkaline than the aqueous solution used in the development step. Examples of the strongly alkaline aqueous solution include a 1 to 10 mass % aqueous solution of sodium hydroxide and a 1 to 10 mass % aqueous solution of potassium hydroxide.

[0091] When the resist pattern is removed after plating, the conductor layer covered with the resist is further etched by etching to form a conductor pattern, thereby manufacturing a desired printed wiring board. The etching method used here is appropriately selected depending on the conductor layer to be removed. For example, the above-mentioned etching solution can be used.

[0092] The method for manufacturing a printed wiring board according to this embodiment can be applied to the manufacture of not only single-layer printed wiring boards but also multi-layer printed wiring boards, and can also be applied to the manufacture of printed wiring boards having small-diameter through holes.

[0093] The present disclosure will be explained in more detail below using examples, but the present invention is not limited to these examples.

[0094] [Synthesis of Binder Polymer] As polymerizable monomers, compounds having the following homopolymer Tg were prepared: AA: acrylic acid (Tg: 106°C) MAA: methacrylic acid (Tg: 228°C) ST: styrene (Tg: 100°C) TCDMA: dicyclopentanyl methacrylate (Tg: 175°C) HEMA: hydroxyethyl methacrylate (Tg: 55°C) BZMA: benzyl methacrylate (Tg: 54°C)

[0095] Synthesis Example 1: 100.4 g of acrylic acid (AA), 308.9 g of styrene (ST), and 29.7 g of dicyclopentanyl methacrylate (TCDMA) (AA / ST / TCDMA mass ratio = 23 / 70 / 7) as polymerizable monomers were mixed with 2.2 g of azobisisobutyronitrile (AIBN) as a thermal radical polymerization initiator and 129.5 g of propylene glycol monomethyl ether as a solvent to prepare a mixture (x). 5.5 g of AIBN was dissolved in 26.3 g of propylene glycol monomethyl ether to prepare a solution (a).

[0096] A flask equipped with a stirrer, dropping funnel, condenser, thermometer, and gas inlet tube was charged with 45.6 g of propylene glycol monomethyl ether and 175.1 g of toluene, and the mixture was stirred under a nitrogen atmosphere while replacing the gas, and the temperature was raised to 80°C. Next, mixture (x) was added dropwise to the flask over 2 hours. After the dropwise addition was completed, the mixture was stirred at 80°C for 2 hours, and then solution (a) was added and stirred for an additional 3 hours. Next, with continued stirring, the solution in the flask was heated to 100°C over 20 minutes, and then stirred at 100°C for 2 hours. Next, 93.7 g of propylene glycol monomethyl ether and 74.3 g of toluene were added, and the mixture was cooled to room temperature with stirring to obtain a solution of binder polymer (A-1) (solid content: 50% by mass).

[0097] Synthesis Example 2 A solution of binder polymer (A-2) (solid content: 50% by mass) was obtained under the same conditions as in Synthesis Example 1, except that the types and amounts of the polymerizable monomers in the mixture (x) were changed to the polymerizable monomers and mass ratios shown in Table 1.

[0098]

[0099] (Weight-average molecular weight) As a sample for Mw measurement, a polymer solution was dissolved in tetrahydrofuran (THF) to prepare a 0.2 mass% THF solution. Mw was measured by gel permeation chromatography (GPC) and calculated by conversion using a calibration curve of standard polystyrene. The GPC conditions are as follows: Measuring apparatus: Shodex (registered trademark) GPC-101 (manufactured by Resonac Co., Ltd.) Detector: Differential refractometer Shodex RI-71S (manufactured by Resonac Co., Ltd.) Column: Shodex LF-804 + LF-804 (manufactured by Resonac Co., Ltd.) Column temperature: 40°C Eluent: THF Flow rate: 1 mL / min

[0100] (Glass Transition Temperature) The Tg of the binder polymer was calculated using the Fox formula.

[0101] (Acid Value) The acid value of the binder polymer was measured by neutralization titration in accordance with JIS K6901:2008 5.3.2.

[0102] [Photosensitive resin composition] A photosensitive resin composition was prepared by mixing 57.0 parts by mass of the solid content of the binder polymer solution with each component in the amount (parts by mass) shown in Table 2 and a sensitizer (EAB: 4,4'-bis(diethylamino)benzophenone (manufactured by Hodogaya Chemical Co., Ltd.)) in the amount (parts by mass) shown in Table 3. Details of each component shown in Table 2 are as follows.

[0103]

[0104] (Photopolymerizable Compounds) FA-321M: 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (manufactured by Resonac Corporation) FA-024M: EOPO-modified dimethacrylate (manufactured by Resonac Corporation) BP-2EM: 2,2-bis(4-(methacryloxydiethoxy)phenyl)propane (manufactured by Kyoeisha Chemical Co., Ltd.) (Photopolymerization Initiator) B-CIM: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Hampford Chemical Co., Ltd.) (Polymerization Inhibitor) Q-TBC-5P: 4-tert-butylcatechol (manufactured by DIC Corporation) LA-7RD: 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (manufactured by ADEKA Corporation) (Photocolor Forming Agent) LCV: Leuco Crystal Violet (manufactured by Yamada Chemical Industry Co., Ltd.) (adhesion imparting agent) SF-808H: mixture of carboxybenzotriazole, 5-amino-1H-tetrazole and methoxypropanol (manufactured by Sanwa Kasei Co., Ltd.) (dye) MKG: Malachite Green (manufactured by Osaka Organic Chemical Industry Ltd.)

[0105] [Photosensitive element] A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "QS-69") was prepared as a support. A photosensitive resin composition was applied onto the support and then dried in a hot air convection dryer at 80°C and 120°C successively to form a photosensitive layer having a thickness after drying shown in Table 3. A polyethylene film (manufactured by Tamapoly Corporation, trade name "NF-15") was laminated onto this photosensitive layer as a protective layer to obtain a photosensitive element in which the support, photosensitive layer, and protective layer were laminated in that order.

[0106] [Laminate] A copper-clad laminate (manufactured by Resonac Corporation, product name "MCL-E-679"), a glass epoxy material with copper foil (thickness: 35 μm) laminated on both sides, was surface-treated by water washing, pickling, and water washing, and then dried in an air stream. The surface-treated copper-clad laminate was heated to 80°C, and while peeling off the protective layer, a photosensitive element was laminated onto the copper-clad laminate so that the photosensitive layer was in contact with the copper surface. This resulted in a laminate in which the copper-clad laminate, photosensitive layer, and support were laminated in this order. Lamination was performed using a 110°C heat roll at a compression pressure of 0.4 MPa and a roll speed of 1.05 m / min.

[0107] [Evaluation] (Minimum Development Time) The laminate was cut into 5 cm squares to obtain test pieces for measuring the minimum development time. After peeling the support from the test piece, the unexposed photosensitive layer was spray-developed at a pressure of 0.15 MPa using a 1% by mass aqueous sodium carbonate solution at 30°C. The minimum development time (unit: seconds) was determined as the shortest time required for visually confirming that an unexposed portion of 1 mm or more had been removed. A full-cone type nozzle was used for spray development. The distance between the test piece and the nozzle tip was 6 cm, and the nozzle was positioned so that the center of the test piece coincided with the center of the nozzle. The shorter the minimum development time, the better the developability. The results are shown in Table 3.

[0108] (Adhesion) A test pattern having a line width (L) / space width (S) of x / 3x (x=1 to 100, unit: μm, changed in 1 μm intervals) was placed on the support of the laminate as a negative mask for evaluating adhesion, and exposure was performed using a parallel light exposure device (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201") using a high-pressure mercury lamp as a light source, at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 14.

[0109] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and the unexposed portions were removed by spraying a 1% by weight aqueous solution of sodium carbonate at 30°C for 50 seconds. After development, the space portions (unexposed portions) were removed without residue, and the line portions (exposed portions) were formed without meandering or chipping. Adhesion was evaluated based on the minimum line width (unit: μm) in the resist pattern. The smaller this value, the better the adhesion. The ratio of the thickness of the resist pattern to this value (aspect ratio of the resist pattern) was also calculated. The results are shown in Table 3.

[0110] (Resolution) A resolution evaluation mask having a grid-like pattern of dots with diameters of 1 to 100 μm was placed on the support of the laminate. Then, using a parallel light exposure device (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201") using a high-pressure mercury lamp as a light source, exposure was performed at an exposure amount such that the number of remaining steps after development of a 41-step tablet would be 14.

[0111] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and a 1% by mass aqueous sodium carbonate solution at 30°C was sprayed on the layer for twice the minimum development time (the shortest time required to remove the unexposed portion) to remove the unexposed portion. This formed a resist pattern (dot pattern). The formed via pattern (via hole pattern) was then observed and evaluated using an optical microscope. The resolution (via pattern) was evaluated based on the smallest via pattern diameter among the via patterns arranged in a lattice pattern that were completely removed (opened). The smaller this value, the better the resolution. The ratio of the resist pattern thickness to this resolution (resist pattern thickness / resolution, hereinafter also referred to as the "via aspect ratio") was also calculated. The results are shown in Table 3.

[0112] (Removability) A glass chrome type phototool (having a 45 mm × 60 mm planar pattern) was placed on the support of the laminate as a negative mask for evaluating peel test. Then, using a parallel light exposure device (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201") using a high-pressure mercury lamp as a light source, exposure was performed at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 14.

[0113] After exposure, the support was peeled from the laminate to expose the photosensitive layer, and the unexposed areas were removed by spraying a 1% by weight aqueous sodium carbonate solution at 30°C for twice the minimum development time, yielding a substrate on which a cured film had been formed. After leaving this substrate at room temperature for 3 hours, it was immersed in an amine-based stripping solution (aqueous solution of 6% by volume R-100S + 2% by volume R-101, manufactured by Mitsubishi Gas Chemical Company, Inc.) heated to 50°C and stirred at 400 rpm. The peeling time (unit: seconds) was the time from the start of stirring until the cured film was completely removed from the substrate. A shorter peeling time indicates better removability. The results are shown in Table 3.

[0114]

[0115] 1... photosensitive element, 2... support, 3... photosensitive layer, 4... protective layer.

Claims

1. A photosensitive resin composition comprising a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the binder polymer has a structural unit derived from acrylic acid, and the content of the sensitizer is less than 0.01 parts by mass per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

2. The photosensitive resin composition according to claim 1, wherein the content of the sensitizer is 0.65 parts by mass or less per 100 parts by mass of the total amount of the photopolymerization initiator.

3. A photosensitive resin composition according to claim 1 or 2, wherein the content of the sensitizer is 0.001 parts by mass or more per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

4. The photosensitive resin composition according to any one of claims 1 to 3, wherein the binder polymer further comprises at least one selected from the group consisting of a structural unit derived from styrene or a styrene derivative, and a structural unit derived from a (meth)acrylate compound having an alicyclic structure.

5. The photosensitive resin composition according to any one of claims 1 to 4, wherein the sensitizer comprises at least one selected from the group consisting of dialkylaminobenzophenone compounds, pyrazoline compounds, and anthracene compounds.

6. A photosensitive element comprising a support and a photosensitive layer formed on the support using the photosensitive resin composition according to any one of claims 1 to 5.

7. The photosensitive element of claim 6, wherein the photosensitive layer has a thickness of 30 μm or greater.

8. A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of claims 1 to 5; irradiating at least a portion of the photosensitive layer with active light rays to form a photocured portion; and removing an unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

9. A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to claim 6 or 7; irradiating at least a portion of the photosensitive layer with active light rays to form a photocured portion; and removing an unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

10. A method for producing a printed wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to claim 8, to form a conductor pattern.

11. A method for producing a printed wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to claim 9, to form a conductor pattern.

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