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

Abstract

A photosensitive resin composition according to the present disclosure contains a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, in which the binder polymer has a structural unit (a1) derived from a polymerizable monomer having a carboxy group, a structural unit (a2) derived from styrene or a styrene derivative, a structural unit (a3) derived from alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms, and a structural unit (a4) derived from alkyl (meth)methacrylate having an alkyl group having 4 to 12 carbon atoms. No accompanying figure

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 layer formed on a support film 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.

[0003] A printed wiring board is manufactured using the photosensitive element, for example, by the following procedure. That is, first, the photosensitive layer of the photosensitive element is laminated onto a circuit-forming substrate such as a copper-clad laminate. Next, the photosensitive layer is exposed to light through a mask film or the like to form a photocured portion. At this time, the support film is peeled off before or after exposure. Thereafter, the area of ​​the photosensitive layer other than the photocured portion is removed with a developer to form a resist pattern. Next, using the resist pattern as a resist, an etching process or a plating process is performed to form a conductor pattern, and finally, the photocured portion of the photosensitive layer (resist pattern) is peeled off (removed).

[0004] In recent years, with the increasing density of printed wiring boards and the advancement of finer conductor patterns, the contact area between the circuit-forming substrate and the photosensitive layer serving as a resist is becoming smaller. Therefore, the photosensitive layer is required to have excellent properties in etching or plating processes, as well as excellent adhesion to the circuit-forming substrate and excellent resolution in forming the resist pattern.

[0005] For example, Patent Document 1 discloses a photosensitive resin composition that is excellent in sensitivity and resolution by using a specific sensitizing dye, and Patent Document 2 discloses a photosensitive resin composition that is excellent in sensitivity and resolution by using a specific alkali-soluble polymer and a compound having an ethylenic double bond.

[0006] JP 2009-003177 A JP 2013-061556 A

[0007] When laminating the photosensitive layer of the photosensitive element onto the circuit-forming substrate, if the photosensitive layer has poor conformability to the circuit-forming substrate, minute gaps may be generated between the photosensitive layer and the circuit-forming substrate, which may affect the formation of the conductor pattern. Therefore, the photosensitive layer is required to have excellent conformability to the circuit-forming substrate.

[0008] The present disclosure aims to provide a photosensitive resin composition capable of forming a photosensitive layer that has excellent conformability to a circuit-forming substrate, a photosensitive element using the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a printed wiring board.

[0009] The photosensitive resin composition according to the present disclosure contains a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, and the binder polymer has a structural unit (a1) derived from a polymerizable monomer having a carboxy group, a structural unit (a2) derived from styrene or a styrene derivative, a structural unit (a3) ​​derived from an alkyl(meth)acrylate having an alkyl group with 1 to 3 carbon atoms, and a structural unit (a4) derived from an alkyl(meth)methacrylate having an alkyl group with 4 to 12 carbon atoms.

[0010] The photosensitive element according to the present disclosure comprises a support and a photosensitive layer formed on the support, and the photosensitive layer contains the above-described photosensitive resin composition.

[0011] The method for forming a resist pattern according to the present disclosure includes the steps of forming a photosensitive layer on a substrate using the above-described photosensitive resin composition or photosensitive element, irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion, and removing at least a portion of the unphotocured portion of the photosensitive layer from the substrate.

[0012] A method for manufacturing a printed wiring board according to the present disclosure includes a step of etching or plating a substrate on which a resist pattern has been formed by the above-described method for forming a resist pattern to form a conductor pattern.

[0013] According to the present disclosure, it is possible to provide a photosensitive resin composition capable of forming a photosensitive layer that has excellent conformability to a circuit-forming substrate, a photosensitive element using the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a printed wiring board.

[0014] 1 is a schematic cross-sectional view showing one embodiment of a photosensitive element. 2 is a diagram showing an example of a manufacturing process for a printed wiring board.

[0015] The present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiments. 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. In this specification, the term "layer" includes a structure having a shape formed on the entire surface as well as a structure having a shape formed on a portion thereof when observed in a plan view.

[0016] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, in numerical ranges described in stages in this specification, the upper or lower limit of a numerical range in a certain stage may be replaced with the upper or lower limit of a numerical range in another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. When referring to the amount of each component in a composition in this specification, if the composition contains multiple substances corresponding to each component, the total amount of the multiple substances present in the composition is meant, unless otherwise specified.

[0017] In this specification, "(meth)acrylic acid" means at least one of "acrylic acid" and the corresponding "methacrylic acid," and the same applies to other similar expressions such as (meth)acrylate. In this specification, "solid content" refers to the non-volatile content excluding volatile substances such as water and solvent contained in the photosensitive resin composition, and indicates the components that remain without volatilization when the resin composition is dried, and also includes liquid, starch syrup-like, and wax-like components at room temperature around 25°C.

[0018] [Photosensitive Resin Composition] The photosensitive resin composition according to this embodiment contains a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, and the binder polymer has a structural unit (a1) derived from a polymerizable monomer having a carboxy group, a structural unit (a2) derived from styrene or a styrene derivative, a structural unit (a3) ​​derived from an alkyl(meth)acrylate having an alkyl group with 1 to 3 carbon atoms, and a structural unit (a4) derived from an alkyl(meth)methacrylate having an alkyl group with 4 to 12 carbon atoms. Each component used in the photosensitive resin composition according to this embodiment will be described in detail below.

[0019] (Component (A): Binder Polymer) The component (A) according to this embodiment contains a binder polymer having a structural unit (a1) having a carboxy group, a structural unit (a2) derived from styrene or a styrene derivative, a structural unit (a3) ​​derived from an alkyl(meth)acrylate having an alkyl group with 1 to 3 carbon atoms, and a structural unit (a4) derived from an alkyl(meth)methacrylate having an alkyl group with 4 to 12 carbon atoms.

[0020] From the viewpoint of alkaline developability, the binder polymer has a structural unit (a1). Examples of polymerizable monomers having a carboxy group include (meth)acrylic acid, α-bromoacrylic acid, α-chloroacrylic acid, β-furyl(meth)acrylic acid, β-styryl(meth)acrylic acid, maleic acid, maleic anhydride, maleic acid monoesters such as monomethyl maleate, monoethyl maleate, and monoisopropyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. From the viewpoint of further improving alkaline developability, the polymerizable monomer having a carboxy group may be either (meth)acrylic acid or methacrylic acid.

[0021] From the viewpoint of improving alkaline developability and tracking ability in a balanced manner, the content of the structural unit (a1) may be 10 to 30% by mass, 15 to 28% by mass, or 20 to 26% by mass, based on the total amount of component (A). When the content of the structural unit (a1) is 10% by mass or more, alkaline developability tends to be improved, and when it is 30% by mass or less, tracking ability tends to be excellent.

[0022] From the viewpoint of resolution, the binder polymer has the structural unit (a2). The styrene derivative is a polymerizable compound in which a hydrogen atom at the α-position or on the aromatic ring of styrene such as vinyltoluene or α-methylstyrene is substituted.

[0023] From the standpoint of improving alkali developability and tracking ability in a balanced manner, the content of the structural unit (a2) in the component (A) may be 10 to 50% by mass, 12 to 45% by mass, or 14 to 44% by mass, based on the total amount of the component (A).

[0024] From the viewpoint of resolution, the binder polymer has the structural unit (a3). Examples of the alkyl(meth)acrylate having an alkyl group having 1 to 3 carbon atoms include methyl(meth)acrylate, ethyl(meth)acrylate, and propyl(meth)acrylate.

[0025] From the viewpoint of improving alkaline developability and tracking ability in a balanced manner, the content of the structural unit (a3) ​​in the component (A) may be 5 to 70% by mass, 12 to 65% by mass, or 15 to 64% by mass, based on the total amount of the component (A). When the content of the structural unit (a3) ​​is 5% by mass or more, alkaline developability tends to be improved, and when it is 70% by mass or less, tracking ability tends to be excellent.

[0026] The binder polymer has the structural unit (a4) from the viewpoint of followability. The alkyl group having 4 to 12 carbon atoms may be a linear or branched alkyl group. Examples of alkyl (meth)methacrylates having an alkyl group having 4 to 12 carbon atoms include butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate.

[0027] From the standpoint of improving alkali developability and tracking ability in a balanced manner, the content of the structural unit (a4) in the component (A) may be 0.5 to 30% by mass, 0.8 to 25% by mass, or 1 to 22% by mass, based on the total amount of the component (A).

[0028] The component (A) may further have a structural unit (a5) other than the structural units (a1) to (a4). Examples of polymerizable monomers for introducing the structural unit (a5) include benzyl (meth)acrylate or a derivative thereof, acrylamides such as diacetone acrylamide, vinyl alcohol ether compounds such as vinyl-n-butyl ether, acrylonitrile, cycloalkyl (meth)acrylate, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl acrylate, and the like. Examples of the acrylates include 2,2,3,3-tetrafluoropropyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, isobornyloxyethyl (meth)acrylate, cyclohexyloxyethyl (meth)acrylate, adamantyloxyethyl (meth)acrylate, dicyclopentenyloxypropyloxyethyl (meth)acrylate, dicyclopentanyloxypropyloxyethyl (meth)acrylate, dicyclopentenyloxypropyloxyethyl (meth)acrylate, and adamantyloxypropyloxyethyl (meth)acrylate. These can be used alone or in any combination of two or more.

[0029] The acid value of the component (A) may be 100 mgKOH / g or more, 110 mgKOH / g or more, 120 mgKOH / g or more, or 130 mgKOH / g or more from the viewpoint of further improving the balance of developability, resolution, and tracking ability. The acid value of the component (A) may be 180 mgKOH / g or less, 170 mgKOH / g or less, 165 mgKOH / g or less, or 160 mgKOH / g or less from the viewpoint of further improving the tracking ability of the photosensitive layer. The acid value of the binder polymer may be 100 mgKOH / g or more to 180 mgKOH / g or less, 110 mgKOH / g or more to 170 mgKOH / g or less, 120 mgKOH / g or more to 165 mgKOH / g or less, or 130 mgKOH / g or more to 160 mgKOH / g or less.

[0030] In terms of even better developability, the weight average molecular weight (Mw) of the component (A) may be 60,000 or less, 56,000 or less, 54,000 or less, or 52,000 or less. In terms of even better adhesion, the Mw of the component (A) may be 10,000 or more, 15,000 or more, 20,000 or more, or 25,000 or more. The weight average molecular weight of the binder polymer may be 10,000 or more and 60,000 or less, 15,000 or more and 56,000 or less, 20,000 or more and 54,000 or less, or 25,000 or more and 52,000 or less.

[0031] The dispersity (weight average molecular weight / number average molecular weight) of component (A) may be 3.0 or less, 2.8 or less, or 2.5 or less, in order to achieve even better resolution and adhesion. A smaller dispersity tends to improve resolution. The weight average molecular weight and number average molecular weight are measured by gel permeation chromatography (GPC) and are values ​​converted using standard polystyrene as a standard sample.

[0032] The glass transition temperature (Tg) of the component (A) may be 80 to 130°C, 85 to 125°C, or 90 to 120°C, in order to further improve conformability.

[0033] The component (A) can be used alone or in combination of two or more. When two or more types of the component (A) are used in combination, examples of the component (A) include two or more binder polymers made of different polymerizable monomers, two or more binder polymers having different Mw, and two or more binder polymers having different dispersities.

[0034] The content of component (A) may be 30 to 80 parts by mass, 40 to 75 parts by mass, 50 to 70 parts by mass, or 50 to 60 parts by mass, relative to 100 parts by mass of the total amount of components (A) and (B). When the content of component (A) is within this range, the strength of the photocured portion of the photosensitive layer is improved.

[0035] (Component (B): Photopolymerizable Compound) The component (B) is not particularly limited as long as it has at least one ethylenically unsaturated bond and is a photopolymerizable compound. The ethylenically unsaturated bond is not particularly limited as long as it is photopolymerizable. Examples of the ethylenically unsaturated bond include α,β-unsaturated carbonyl groups such as a (meth)acryloyl group.

[0036] Examples of photopolymerizable compounds having an α,β-unsaturated carbonyl group include α,β-unsaturated carboxylic acid esters of polyhydric alcohols, bisphenol-type (meth)acrylates, α,β-unsaturated carboxylic acid adducts of glycidyl group-containing compounds, (meth)acrylates having a urethane bond, nonylphenoxy polyethyleneoxy acrylate, and (meth)acrylic acid alkyl esters.

[0037] Examples of α,β-unsaturated carboxylic acid esters of polyhydric alcohols include polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups, polypropylene glycol di(meth)acrylate having 2 to 14 propylene groups, polyethylene-polypropylene glycol di(meth)acrylate having 2 to 14 ethylene groups and 2 to 14 propylene groups, 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, tetramethylolmethane tetra(meth)acrylate, and (meth)acrylate compounds having a skeleton derived from dipentaerythritol or pentaerythritol. "EO-modified" means having a block structure of ethylene oxide (EO) groups, and "PO-modified" means having a block structure of propylene oxide (PO) groups.

[0038] From the viewpoint of improving the flexibility of the resist pattern, the component (B) may contain a polyalkylene glycol di(meth)acrylate. The polyalkylene glycol di(meth)acrylate may have at least one of an EO group and a PO group, or may have both an EO group and a PO group. In a polyalkylene glycol di(meth)acrylate having both an EO group and a PO group, the EO groups and the PO groups may each be present in succession in a block form, or may be present randomly. The PO group may be either an oxy-n-propylene group or an oxyisopropylene group. In the (poly)oxyisopropylene group, the secondary carbon of the propylene group may be bonded to an oxygen atom, or the primary carbon may be bonded to an oxygen atom.

[0039] Commercially available polyalkylene glycol di(meth)acrylates include, for example, FA-023M (manufactured by Showa Denko Materials Co., Ltd.), FA-024M (manufactured by Showa Denko Materials Co., Ltd.), and NK Ester HEMA-9P (manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0040] From the viewpoint of improving the flexibility of the resist pattern, component (B) may contain a (meth)acrylate having a urethane bond. Examples of (meth)acrylates having a urethane bond include an addition reaction product of a (meth)acrylic monomer having an OH group at the β-position with a diisocyanate (such as isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, or 1,6-hexamethylene diisocyanate), tris((meth)acryloxytetraethylene glycol isocyanate)hexamethylene isocyanurate, EO-modified urethane di(meth)acrylate, and EO,PO-modified urethane di(meth)acrylate.

[0041] Commercially available EO-modified urethane di(meth)acrylates include, for example, "UA-11" and "UA-21EB" (manufactured by Shin-Nakamura Chemical Co., Ltd.). Commercially available EO, PO-modified urethane di(meth)acrylates include, for example, "UA-13" (manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0042] From the viewpoints of facilitating the formation of a thick resist pattern and improving resolution and adhesion in a balanced manner, the component (B) may contain a (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol. The (meth)acrylate compound having a skeleton derived from dipentaerythritol preferably has four or more (meth)acryloyl groups, and may be dipentaerythritol penta(meth)acrylate or dipentaerythritol hexa(meth)acrylate.

[0043] From the viewpoint of further improving resolution and release properties after curing, component (B) may contain a bisphenol type (meth)acrylate, and among bisphenol type (meth)acrylates, it may contain bisphenol A type (meth)acrylate. Examples of bisphenol A type (meth)acrylates 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. Of these, from the viewpoint of further improving resolution and pattern formability, 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is preferred.

[0044] Examples of commercially available 2,2-bis(4-((meth)acryloxydipropoxy)phenyl)propane include BPE-200 (Shin-Nakamura Chemical Co., Ltd.), and examples of 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane include BPE-500 (Shin-Nakamura Chemical Co., Ltd.) and FA-321M (Showa Denko Materials K.K.).

[0045] Examples of nonylphenoxy polyethyleneoxyacrylates include nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate, nonylphenoxynonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, and nonylphenoxyundecaethyleneoxyacrylate.

[0046] The content of component (B) is preferably 20 to 60 parts by mass, more preferably 30 to 55 parts by mass, and even more preferably 35 to 50 parts by mass, per 100 parts by mass of the total amount of components (A) and (B). When the content of component (B) is within this range, the photosensitive resin composition exhibits improved photosensitivity and film-forming properties in addition to improved resolution, adhesion, and resistance to resist tailing.

[0047] (Component (C): Photopolymerization Initiator) The component (C) is not particularly limited as long as it can polymerize the component (B), and can be appropriately selected from commonly used photopolymerization initiators. From the viewpoint of improving pattern formability, examples of the photopolymerization initiator include those that generate free radicals when exposed to actinic rays, such as acylphosphine oxide-based, oxime ester-based, aromatic ketone-based, quinone-based, alkylphenone-based, imidazole-based, acridine-based, phenylglycine-based, and coumarin-based photopolymerization initiators.

[0048] The component (C) may contain an acridine-based photopolymerization initiator, a phenylglycine-based photopolymerization initiator, or an imidazole-based photopolymerization initiator, and preferably contains an acridine-based photopolymerization initiator, from the viewpoint of improving sensitivity and resolution in a balanced manner. The component (C) can be used alone or in combination of two or more types.

[0049] Examples of the acridine-based photopolymerization initiator include 9-phenylacridine, 9-(p-methylphenyl)acridine, 9-(m-methylphenyl)acridine, 9-(p-chlorophenyl)acridine, 9-(m-chlorophenyl)acridine, 9-aminoacridine, 9-dimethylaminoacridine, 9-diethylaminoacridine, 9-pentylaminoacridine, 1,2-bis(9-acridinyl)ethane, 1,4-bis(9-acridinyl)butane, 1,6-bis(9-acridinyl)hexane, and 1,8-bis(9-acridinyl)octadecane. bis(9-acridinyl)alkanes such as 1,10-bis(9-acridinyl)decane, 1,12-bis(9-acridinyl)dodecane, 1,14-bis(9-acridinyl)tetradecane, 1,16-bis(9-acridinyl)hexadecane, 1,18-bis(9-acridinyl)octadecane, and 1,20-bis(9-acridinyl)eicosane; 1,3-bis(9-acridinyl)-2-oxapropane, 1,3-bis(9-acridinyl)-2-thiapropane, and 1,5-bis(9-acridinyl)-3-thiapentane.

[0050] Examples of the phenylglycine-based photopolymerization initiator include N-phenylglycine, N-methyl-N-phenylglycine, and N-ethyl-N-phenylglycine.

[0051] Examples of the imidazole-based photopolymerization initiator include 2-(o-chlorophenyl)-4,5-diphenylbiimidazole, 2,2',5-tris-(o-chlorophenyl)-4-(3,4-dimethoxyphenyl)-4',5'-diphenylbiimidazole, 2,4-bis-(o-chlorophenyl)-5-(3,4-dimethoxyphenyl)-diphenylbiimidazole, 2,4,5-tris-(o-chlorophenyl)-diphenylbiimidazole, 2-(o-chlorophenyl)-bis-4,5-(3,4-dimethoxyphenyl)-biimidazole, 2,2' 2,2'-bis-(2-fluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,3-difluoromethylphenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2'-bis-(2,4-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole, and 2,2'-bis-(2,5-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole.

[0052] The amount of component (C) may be 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, 0.4 to 3 parts by mass, or 0.5 to 2 parts by mass, relative to 100 parts by mass of the total amount of component (A) and component (B). When the amount of component (C) is 0.1 part by mass or more, photosensitivity, resolution, and adhesion tend to be improved, while when it is 10 parts by mass or less, resist pattern formability tends to be better.

[0053] (Component (D): Sensitizer) The photosensitive resin composition according to this embodiment may further contain, as component (D), a sensitizer having absorption in the range of 340 to 430 nm. This further improves the photosensitivity of the photosensitive resin composition. Examples of sensitizers include dialkylaminobenzophenone compounds, pyrazoline compounds, anthracene compounds, coumarin compounds, xanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, naphthalimide compounds, and triarylamine compounds. From the viewpoints of sensitivity and adhesion, the sensitizer may include at least one selected from the group consisting of pyrazoline compounds, anthracene compounds, coumarin compounds, and triarylamine compounds, and may include at least one selected from the group consisting of pyrazoline compounds, anthracene compounds, and coumarin compounds.

[0054] Examples of pyrazoline compounds include 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)pyrazoline, 1-phenyl-3-(4-tert-butylstyryl)-5-(4-tert-butylphenyl)pyrazoline, and 1-phenyl-3-biphenyl-5-(4-tert-butylphenyl)pyrazoline. Examples of anthracene compounds include 9,10-dibutoxyanthracene and 9,10-diphenylanthracene. Examples of coumarin compounds include 3-benzoyl-7-diethylaminocoumarin, 7-diethylamino-4-methylcoumarin, 3,3'-carbonylbis(7-diethylaminocoumarin), and 2,3,6,7-tetrahydro-9-methyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]kyrolidin-11-one.

[0055] When the photosensitive resin composition contains the (D) component, the content of the (D) component may be 0.01 to 10 mass%, 0.05 to 5 mass%, or 0.1 to 3 mass%, based on the total solid content of the photosensitive resin composition. When the (D) component is 0.01 mass% or more, sensitivity and resolution are further improved, and when the (D) component is 10 mass% or less, the resist shape is prevented from becoming an inverted trapezoid, and adhesion is further improved. From the viewpoint of a balance between resolution and adhesion, the content of the (D) component may be 0.005 to 0.5 parts by mass, 0.008 to 0.2 parts by mass, or 0.01 to 0.1 parts by mass, relative to 100 parts by mass of the total amount of the (A) component and the (B) component.

[0056] (Component (E): Heat Stabilizer) The photosensitive resin composition according to this embodiment may further contain a heat stabilizer as component (E). Examples of component (E) include quinone derivatives such as benzoquinone and hydroquinone, phenol derivatives (hindered phenol derivatives) such as 4-methoxyphenol and 4-t-butylcatechol, aminoxyl derivatives such as 2,2,6,6-tetramethylpiperidine-1-oxyl and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and hindered amine derivatives such as tetramethylpiperidyl methacrylate. In particular, by using an aminoxyl derivative as component (E), the photosensitive resin composition can have good sensitivity, while the resolution and adhesion of the formed resist pattern can be further improved.

[0057] The content of component (E) may be 0.005 to 10 parts by mass, 0.01 to 8 parts by mass, or 0.01 to 5 parts by mass, relative to 100 parts by mass of the total amount of component (A). When the content of component (E) is 0.005 parts by mass or more, resolution and adhesion tend to be better, and when it is 10 parts by mass or less, sensitivity tends to be better. The content of component (E) may be 0.005 to 20 parts by mass, 0.01 to 5 parts by mass, or 0.02 to 1 part by mass, relative to 100 parts by mass of the total amount of component (A) and component (B). When this content is 0.005 parts by mass or more, resolution and suppression of resist tail generation tend to be better, and when it is 20 parts by mass or less, sensitivity tends to be better.

[0058] (Other Components) The photosensitive resin composition according to this embodiment may further contain, as necessary, additives such as dyes, photocoloring agents, thermal color-developing inhibitors, plasticizers, pigments, fillers, defoamers, flame retardants, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, thermal crosslinking agents, polymerization inhibitors, etc. These additives may be used alone or in combination of two or more.

[0059] Examples of dyes include malachite green, Victoria Pure Blue, brilliant green, and methyl violet. Examples of photochromic agents include tribromophenyl sulfone, leuco crystal violet, diphenylamine, benzylamine, triphenylamine, diethylaniline, and o-chloroaniline. Examples of plasticizers include p-toluenesulfonamide.

[0060] The content of the additive may be 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, or 0.1 to 3 parts by mass, respectively, per 100 parts by mass of the total amount of the components (A) and (B).

[0061] The photosensitive resin composition can be dissolved, as necessary, in a solvent such as methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, or propylene glycol monomethyl ether, or a mixed solvent thereof, to prepare a solution having a solids content of about 30 to 60 mass %.

[0062] [Photosensitive Element] The photosensitive element of this embodiment comprises a support and a photosensitive layer formed on the support, and the photosensitive layer contains the above-mentioned photosensitive resin composition. When using the photosensitive element of this embodiment, the photosensitive layer may be laminated on a substrate and then exposed without peeling off the support (support film). As shown in the schematic cross-sectional view of an example in Figure 1, the photosensitive element 1 of this embodiment comprises a support 2 and a photosensitive layer 3 derived from the above-mentioned photosensitive resin composition formed on the support 2, and other layers such as a protective layer 4 that are provided as necessary.

[0063] (Support) Examples of the support include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene-2,6-naphthalate (PEN), and polyolefin films such as polypropylene and polyethylene. Among these, PET film may be used because it is easily available and has excellent handleability (particularly heat resistance, heat shrinkage rate, and breaking strength) in the production process.

[0064] The haze of the support may be 0.01 to 1.0% or 0.01 to 0.5%. When the haze is 0.01% or more, the support itself tends to be easier to manufacture, while when it is 1.0% or less, micro-defects that may occur in the resist pattern tend to be reduced. "Haze" refers to cloudiness. The haze in this disclosure refers to a value measured using a commercially available haze meter (turbidity meter) in accordance with the method specified in JIS K 7105. Haze can be measured, for example, using a commercially available turbidity meter such as the NDH-5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0065] The thickness of the support may be 1 to 100 μm, 5 to 60 μm, 10 to 50 μm, 10 to 40 μm, 10 to 30 μm, or 10 to 25 μm. When the thickness of the support is 1 μm or more, it tends to be possible to prevent the support from being torn when peeled off. Furthermore, when the thickness of the support is 100 μm or less, it is possible to prevent a decrease in resolution when exposure is performed through the support.

[0066] (Protective Layer) The photosensitive element may further include a protective layer, if necessary. As the protective layer, a film may be used in which the adhesive strength between the photosensitive layer and the protective layer is smaller than the adhesive strength between the photosensitive layer and the support, or a film with low fisheyes may be used. Specific examples include the films that can be used as the support described above. From the viewpoint of releasability from the photosensitive layer, a polyethylene film may be used as the protective layer. The thickness of the protective layer may vary depending on the application, but may be about 1 to 100 μm.

[0067] The photosensitive element can be produced, for example, as follows: A solution (coating liquid) of the photosensitive resin composition is applied to a support to form a coating layer, which is then dried to form a photosensitive layer. The surface of the photosensitive layer opposite the support is then covered with a protective layer to obtain a photosensitive element comprising the support, the photosensitive layer formed on the support, and the protective layer laminated on the photosensitive layer.

[0068] The coating solution can be applied to the support by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating.

[0069] The drying of the coating layer is not particularly limited as long as it can remove at least a portion of the organic solvent from the coating layer. For example, it may be performed at 70 to 150°C for about 5 to 30 minutes. After drying, the amount of solvent remaining in the photosensitive layer may be 2% by mass or less, from the viewpoint of preventing diffusion of the solvent in subsequent steps.

[0070] The thickness of the photosensitive layer in the photosensitive element can be appropriately selected depending on the application, but may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm after drying. A thickness of 1 μm or more facilitates industrial coating and improves productivity. Furthermore, a thickness of 100 μm or less improves adhesion and resolution.

[0071] The form of the photosensitive element is not particularly limited. For example, it may be in the form of a sheet, or may be in the form of a roll wound around a core. When wound into a roll, it may be wound so that the support film is on the outside. Examples of the core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer).

[0072] An end separator may be provided on the end surface of the roll-shaped photosensitive element to protect the end surface, or a moisture-proof end separator may be provided to prevent edge fusion. The photosensitive element may be wrapped and packaged in a black sheet with low moisture permeability.

[0073] The photosensitive element can be suitably used, for example, in the method for forming a resist pattern described below. In particular, from the viewpoint of resolution, it is suitable for application to a manufacturing method for forming a conductor pattern by etching.

[0074] [Method of Forming a Resist Pattern] The method of forming a resist pattern of this embodiment includes: (i) a step of forming a photosensitive layer on a substrate using the photosensitive resin composition or the photosensitive element (photosensitive layer forming step); (ii) a step of irradiating at least a portion (predetermined portion) of the photosensitive layer with actinic light to form a photocured portion (exposure step); and (iii) a step of removing at least a portion of the unphotocured portion 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.

[0075] (i) Photosensitive Layer Forming Step) The photosensitive layer can be formed on a substrate by, for example, applying and drying the photosensitive resin composition, or by removing the protective layer from the photosensitive element and then pressing the photosensitive layer of the photosensitive element onto the substrate while heating. When a photosensitive element is used, a laminate is obtained that is composed of a substrate, a photosensitive layer, and a support, which are laminated in this order. The substrate is not particularly limited, but is 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.

[0076] When a photosensitive element is used, the photosensitive layer forming step is preferably 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 for pressure bonding is 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.

[0077] (ii) Exposure Step) In the exposure step, at least a part of the photosensitive layer formed on the substrate is irradiated with actinic rays, whereby the part irradiated with the 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 irradiating the photosensitive layer with actinic rays.

[0078] Examples of the exposure method include a method of irradiating an actinic ray imagewise through a negative or positive mask pattern called artwork (mask exposure method). Alternatively, a method of irradiating an actinic ray imagewise by a projection exposure method may be employed. Alternatively, a method of irradiating an actinic ray imagewise by a direct writing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be employed.

[0079] 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.

[0080] ((iii) Development Step) In the development 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.

[0081] 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.

[0082] In the case of wet development, development is 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 improving 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] [Method for manufacturing printed wiring board] The method for manufacturing a printed wiring board of the present embodiment includes a step of etching or plating a substrate on which a resist pattern has been formed by the above-described method for forming a resist pattern to form a conductor pattern, and may also include other steps such as a resist pattern removal step, as necessary.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] An example of a manufacturing process for a printed wiring board using a subtractive method is shown in Figure 2. In Figure 2(a), a substrate (circuit-forming substrate) is prepared in which a conductor layer 40 is formed on an insulating layer 50. The conductor layer 40 is, for example, a copper layer. In Figure 2(b), a photosensitive layer 30 is formed on the conductor layer 40 in the photosensitive layer formation step. Next, in the exposure step, actinic rays are irradiated onto the photosensitive layer 30 by a direct writing method to form a photocured portion in the photosensitive layer 30.

[0095] 2(c), a development process is performed to remove from the substrate areas other than the photocured areas formed in the exposure process, thereby forming a photocured resist pattern 32 on the substrate. In FIG. 2(d), an etching process is performed to remove the conductor layer 40 that is not covered by the resist pattern 32, thereby forming a conductor pattern 42. In FIG. 2(e), the resist pattern 32 is peeled off with a strong alkaline aqueous solution, thereby producing a substrate having a conductor pattern 42.

[0096] 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.

[0097] The objects and advantages of the present embodiment will be explained in more detail below based on examples and comparative examples, but the present embodiment is not limited to the following examples.

[0098] [Binder Polymer] As polymerizable monomers for synthesizing binder polymers used in the Examples and Comparative Examples, methacrylic acid (MAA), styrene (ST), methyl methacrylate (MMA), butyl methacrylate (BMA), butyl acrylate (BA), 2-ethylhexyl acrylate (EHA), ethyl acrylate (AEEC), and benzyl methacrylate (BZMA) were prepared.

[0099] (Binder Polymer (A-1)) 25.5 g of methacrylic acid (MAA), 52.9 g of styrene (ST), 9.9 g of methyl methacrylate (MMA), 3.2 g of butyl acrylate (BA), 23.5 g of benzyl methacrylate (BZMA), 0.02 g of 4-methoxyphenol, and 0.7 g of azobisisobutyronitrile were mixed to prepare solution a. Furthermore, 9 g of propylene glycol monomethyl ether, 7.6 g of toluene, and 0.14 g of azobisisobutyronitrile were mixed to prepare solution b. Furthermore, 4.5 g of propylene glycol monomethyl ether, 7.6 g of toluene, and 0.5 g of azobisisobutyronitrile were mixed to prepare solution c.

[0100] 48 g of propylene glycol monomethyl ether and 40 g of toluene were placed in a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, and a nitrogen gas inlet tube, and the mixture was stirred at 80°C for 30 minutes while blowing nitrogen gas into the flask, to obtain a mixed liquid.

[0101] Solution a was added dropwise to the mixture in the flask over 4 hours, and the mixture was stirred at 80°C for 2 hours. Next, solution b was added dropwise to the solution in the flask, and the mixture was stirred at 80°C for 2 hours. Furthermore, while continuing to stir, the solution in the flask was heated to 95°C over 1 hour, and then solution c was added dropwise over 10 minutes and the mixture was stirred at 95°C for 2 hours to carry out the reaction. The reaction solution was cooled to 50°C, and methanol was added to obtain a solution of binder polymer (A-1). The non-volatile content (solid content) of binder polymer (A-1) was 47.7% by mass.

[0102] (Binder polymers (A-2) to (A-18)) Solutions of binder polymers (A-2) to (A-18) were obtained in the same manner as for obtaining the solution of binder polymer (A-1), except that the polymerizable monomers shown in Table 1 or Table 2 were used in the mass ratios shown in the same table.

[0103] (Weight-average molecular weight) 120 mg of the binder polymer solution was collected and dissolved in 5 mL of tetrahydrofuran to prepare a sample for Mw measurement. Mw was measured by gel permeation chromatography (GPC) and calculated using a calibration curve of standard polystyrene. The GPC conditions are shown below.

[0104] (GPC conditions) Pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd.) Column: Gelpack GL-R440, Gelpack GL-R450, and Gelpack GL-R440M (manufactured by Showa Denko Materials Technoservice Co., Ltd., column specifications: 10.7 mmφ×300 mm) Eluent: tetrahydrofuran Measurement temperature: 40° C. Injection volume: 200 μL Pressure: 49 kgf / cm ２ (4.8 MPa) Flow rate: 2.05 mL / min Detector: Hitachi L-2490 RI (manufactured by Hitachi, Ltd.)

[0105] (Acid Value) The acid value was measured by the neutralization titration method based on JIS K 0070. A mixed solvent (mass ratio: toluene / methanol = 70 / 30) was added to about 1 g of the binder polymer to dissolve it, and an appropriate amount of phenolphthalein solution was added as an indicator to the solution, followed by titration with a 0.1 N potassium hydroxide aqueous solution to measure the acid value of the binder polymer.

[0106] (Glass Transition Temperature) The glass transition temperature (Tg) of the binder polymer was calculated from the Fox equation.

[0107]

[0108]

[0109] [Photosensitive Resin Composition] Photosensitive resin compositions of the Examples and Comparative Examples were prepared by mixing components (A), (B), and (C) in the amounts (parts by mass) shown in Table 3 or Table 4 with 5 parts by mass of methanol, 10 parts by mass of toluene, and 11 parts by mass of acetone as solvents. The amounts of binder polymer shown in Tables 3 and 4 are the masses of nonvolatile components (solid content).

[0110] Details of each component shown in Tables 3 and 4 are as follows: (Component (B): Photopolymerizable Compound) B-1: FA-321M 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (Showa Denko Materials Co., Ltd.) B-2: FA-MECH γ-chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate (Showa Denko Materials Co., Ltd.) B-3: M2200 Ethoxylated bisphenol A dimethacrylate (EO modified with an average of 20 mol) (manufactured by Miwon) B-4: BPE-200 Ethoxylated bisphenol A dimethacrylate (EO modified with an average of 4 mol) (Shin-Nakamura Chemical Co., Ltd.) B-5: SR454 EO-modified trimethylolpropane acrylate (Tomoe Engineering Co., Ltd.) B-6: FA-137M EO-modified trimethylolpropane acrylate (Showa Denko Materials Co., Ltd.) B-7: DPEA-12 Dipentaerythritol (meth)acrylate having an EO group (Nippon Kayaku Co., Ltd.) B-8: UA-21 Tris(methacryloxytetraethylene glycol isocyanate) hexamethylene isocyanurate (Shin-Nakamura Chemical Co., Ltd.) B-9: FA-024M EOPO-modified dimethacrylate (Showa Denko Materials Co., Ltd.) (Component (C): photopolymerization initiator) C-1: 9-PA 9-phenylacridine (Changzhou Powerful New Electronic Materials Co., Ltd.) C-2: N-PG N-phenylglycine (Changzhou Powerful New Electronic Materials Co., Ltd.) C-3: B-CIM 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (Hodogaya Chemical Co., Ltd.) (Component (D): sensitizer) D-1: DBA 9,10-Dibutoxyanthracene (Kawasaki Chemical Industries, Ltd.)

[0111] [Photosensitive element] A solution of the photosensitive resin composition was applied to a 16 μm-thick polyethylene terephthalate (PET) film (Teijin Film Solutions Co., Ltd., trade name "G2J") (support), and dried sequentially in a hot air convection dryer at 75°C and 125°C to form a photosensitive layer having a thickness of 25 μm after drying. A polypropylene film (Tamapoly Co., Ltd., trade name "NF-13") (protective layer) was laminated onto this photosensitive layer, and photosensitive elements having a support, photosensitive layer, and protective layer laminated in this order were obtained.

[0112] (Follow-up ability) The copper surface of a copper-clad laminate was etched to form eight circular holes with a diameter of 200 μm and a depth of 11 μm, thereby preparing a substrate. The substrate was then heated to 80°C, and a photosensitive element was laminated onto the substrate. The lamination was performed using a heat roll at 110°C, while removing the protective layer, at a pressure of 0.3 MPa and a roll speed of 1.5 m / min. Thus, a laminate was obtained in which the substrate, photosensitive layer, and support were laminated in this order. The circular holes were observed from directly above the laminate using an optical microscope (Keyence Corporation, VK-8500), and the diameter of any bubbles generated between the circular holes in the substrate and the photosensitive layer was measured. A smaller bubble diameter indicates better follow-up ability.

[0113]

[0114]

[0115] As is clear from Tables 1 to 4, a photosensitive resin composition containing a binder polymer having a specific structure can form a photosensitive layer with excellent followability.

[0116] 1... photosensitive element, 2... support, 3... photosensitive layer, 4... protective layer.

Claims

1. A photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, wherein the binder polymer has a structural unit (a1) derived from a polymerizable monomer having a carboxy group, a structural unit (a2) derived from styrene or a styrene derivative, a structural unit (a3) ​​derived from an alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms, and a structural unit (a4) derived from an alkyl (meth)methacrylate having an alkyl group with 4 to 12 carbon atoms.

2. The photosensitive resin composition according to claim 1, wherein the acid value of the binder polymer is from 100 mgKOH / g to 180 mgKOH / g.

3. The photosensitive resin composition according to claim 1 or 2, wherein the weight average molecular weight of the binder polymer is 10,000 or more and 60,000 or less.

4. The photosensitive resin composition according to any one of claims 1 to 3, wherein the content of the structural unit (a4) is 0.5 to 30 mass% based on the total amount of the binder polymer.

5. The photosensitive resin composition according to any one of claims 1 to 4, wherein the photopolymerization initiator comprises an acridine-based photopolymerization initiator.

6. The photosensitive resin composition according to any one of claims 1 to 5, wherein the photopolymerizable compound comprises a bisphenol type di(meth)acrylate.

7. The photosensitive resin composition according to any one of claims 1 to 6, wherein the photopolymerizable compound comprises a (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol.

8. A photosensitive element comprising a support and a photosensitive layer formed on the support, the photosensitive layer comprising the photosensitive resin composition according to any one of claims 1 to 7.

9. 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 7 or the photosensitive element according to claim 8; irradiating at least a portion of the photosensitive layer with active light rays to form a photocured portion; and removing at least a portion of the unphotocured portion of the photosensitive layer from the substrate.

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 9, to form a conductor pattern.

11. The method for producing a printed wiring board according to claim 10, further comprising the step of removing the resist pattern after the etching or plating treatment.