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

Abstract

A photosensitive resin composition according to the present disclosure contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer. The photopolymerizable compound contains a monofunctional (meth)acrylate having a bicyclo skeleton. The contained amount of the monofunctional (meth)acrylate having a bicyclo skeleton is less than 5.0 parts by mass with respect 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 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 wiring board.

[0002] In the field of wiring board manufacturing, photosensitive resin compositions and photosensitive elements comprising a layer formed on a 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.

[0003] A wiring board is manufactured, for example, by the following procedure. First, a photosensitive layer of a photosensitive element is laminated onto a circuit-forming substrate (photosensitive layer forming step). Next, a predetermined portion of the photosensitive layer is exposed to light to form a photocured portion (exposure step). At this time, the support is peeled off before or after exposure. Thereafter, areas of the photosensitive layer other than the photocured portion are removed from the substrate, and a resist pattern, which is a cured product of the photosensitive resin composition, is formed on the substrate (developing step). Next, the obtained resist pattern is used as a resist and subjected to etching or plating to form a conductor pattern on the substrate (circuit forming step), and finally the resist is peeled off and removed (peeling step).

[0004] As an exposure method, a method of exposing through a photomask using a mercury lamp as a light source has been conventionally known. Recently, a direct imaging exposure method called LDI (Laser Direct Imaging) has been used as an exposure method that does not require a photomask, in which digital data of a pattern is directly written onto a photosensitive layer. This direct imaging exposure method has better alignment accuracy than exposure methods using a photomask and can produce high-resolution patterns, and is therefore being introduced for the production of high-density packaging substrates.

[0005] In general, in the exposure step, it is desirable to shorten the exposure time in order to improve production efficiency. However, in the above-mentioned direct writing exposure method, monochromatic light such as a laser is used as a light source, and actinic rays are irradiated while scanning the substrate, so that the exposure time tends to be longer than that of a conventional exposure method using a photomask. Therefore, in order to shorten the exposure time and improve production efficiency, it is necessary to further improve the sensitivity of the photosensitive resin composition.

[0006] In the stripping step, it is desirable to shorten the resist stripping time in order to improve production efficiency. Therefore, a photosensitive resin composition that has excellent strippability after curing is required. Furthermore, with the recent trend toward higher density wiring boards, a photosensitive resin composition that can form a resist pattern with excellent resolution and adhesion is also required.

[0007] In response to these demands, various photosensitive resin compositions have been investigated. For example, Patent Document 1 discloses a photosensitive resin composition that is excellent in sensitivity and resolution by using a specific photosensitizer. 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.

[0008] JP 2009-003177 A JP 2013-061556 A

[0009] In recent years, for example, in order to form copper pillars connecting IC chips and wiring boards for semiconductor packages, photosensitive resin compositions are required to form resist patterns such as via hole patterns with high resolution. However, the thicker the photosensitive layer formed using a photosensitive resin composition, the more difficult it is to cure uniformly to the bottom, making it difficult to form a resist pattern with sufficient resolution and adhesion. Furthermore, resist patterns with excellent adhesion tend to require longer peel times. Therefore, photosensitive resin compositions are required to form resist patterns with excellent adhesion and resolution, as well as to have excellent peelability after curing.

[0010] An object of the present disclosure is to provide a photosensitive resin composition that is excellent in resolution, adhesion, and releasability, a photosensitive element that uses the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a wiring board.

[0011] The present disclosure provides the following photosensitive resin composition, photosensitive element, method for forming a resist pattern, and method for manufacturing a wiring board. [1] A photosensitive resin composition containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the photopolymerizable compound contains a monofunctional (meth)acrylate having a bicyclo skeleton, and the content of the monofunctional (meth)acrylate having a bicyclo skeleton is less than 5.0 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 monofunctional (meth)acrylate having a bicyclo skeleton is 1.0 to 4.5 parts by mass per 100 parts by mass of the binder polymer and the photopolymerizable compound. [3] The photosensitive resin composition according to [1] or [2] above, wherein the photopolymerizable compound further contains bisphenol A (meth)acrylate. [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the sensitizer comprises an anthracene compound. [5] 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 [4] above. [6] The photosensitive element according to [5] above, wherein the photosensitive layer has a thickness of 30 μm or more. [7] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to [6] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern. [8] A method for producing a 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 [7] above, to form a conductor pattern. [9] A method for producing a wiring board according to [8] above, further comprising the step of removing the resist pattern using an organic alkaline stripper after the etching or plating.

[0012] According to the present disclosure, it is possible to provide a photosensitive resin composition that is excellent in resolution, adhesion, and releasability, a photosensitive element that uses the photosensitive resin composition, a method for forming a resist pattern, and a method for manufacturing a wiring board.

[0013] FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a photosensitive element.

[0014] Embodiments of the present disclosure are described in detail below. In this specification, the term "process" refers not only to an independent process, but also to a process that is not clearly distinguishable from other processes, as long as the process achieves its intended function. The term "layer" encompasses not only a structure that is formed over the entire surface when viewed in a plan view, but also a structure that is formed only 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 a value shown in an example.

[0015] 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". "EO" refers to ethylene oxide, and an "EO-modified" compound refers to a compound having an oxyethylene group. "PO" refers to propylene oxide, and a "PO-modified" compound refers to a compound having an oxypropylene group.

[0016] 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).

[0017] [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 photopolymerizable compound contains a monofunctional (meth)acrylate having a bicyclo skeleton, and the content of the monofunctional (meth)acrylate having a bicyclo skeleton in the photosensitive resin composition is less than 5.0 parts by mass per 100 parts by mass of the binder polymer and the photopolymerizable compound combined. By containing such a specific photopolymerizable compound in a specific range, the photosensitive resin composition according to this embodiment has excellent resolution, adhesion, and releasability, making it suitable for use in thick film applications. Each component will be described below.

[0018] (Component (A): Binder Polymer) The photosensitive resin composition contains one or more types of component (A). Examples of component (A) include acrylic resins, styrene resins, epoxy resins, amide resins, amide-epoxy resins, alkyd resins, and phenolic resins.

[0019] From the viewpoint of alkali developability, the component (A) may contain an acrylic resin. The acrylic resin is a resin having structural units (monomer units) derived from a (meth)acryloyl group-containing compound.

[0020] The (meth)acryloyl group-containing compound is a compound containing a (meth)acryloyl group. Examples of the (meth)acryloyl group-containing compound include hydroxyalkyl(meth)acrylate, (meth)acrylic acid, (meth)acrylic acid alkyl ester, (meth)acrylic acid aryl ester, (meth)acrylic acid cycloalkyl ester, acrylamide such as diacetone acrylamide, (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid dimethylaminoethyl ester, (meth)acrylic acid diethylaminoethyl ester, (meth)acrylic acid glycidyl ester, 2,2,2-trifluoroethyl(meth)acrylate, 2,2,3,3-tetrafluoropropyl(meth)acrylate, α-bromoacrylic acid, α-chloroacrylic acid, β-furyl(meth)acrylic acid, and β-styryl(meth)acrylic acid.

[0021] The acrylic resin may be, for example, a polymer (a) having at least one unit selected from the group consisting of a (meth)acrylic acid unit, a (meth)acrylic acid alkyl ester unit, a (meth)acrylic acid aryl ester unit, and a hydroxyalkyl (meth)acrylate unit.

[0022] The (meth)acrylic acid unit is a structural unit derived from (meth)acrylic acid. When the polymer (a) has the (meth)acrylic acid unit, the content of the (meth)acrylic acid unit may be 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more, based on the total amount (100% by mass) of the monomer units constituting the polymer (a), from the viewpoints of resolution and adhesion, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less.

[0023] The (meth)acrylic acid alkyl ester unit is a structural unit derived from a (meth)acrylic acid alkyl ester. The alkyl group of the (meth)acrylic acid alkyl ester may be, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, or a structural isomer thereof, or may be an alkyl group having 1 to 4 carbon atoms from the viewpoint of releasability.

[0024] When the polymer (a) has a (meth)acrylic acid alkyl ester unit, the content of the (meth)acrylic acid alkyl ester unit may be 1 mass % or more, 2 mass % or more, or 3 mass % or more, based on the total amount of monomer units constituting the polymer (a), from the viewpoint of releasability, and may be 30 mass % or less, 20 mass % or less, 10 mass % or less, or 8 mass % or less, from the viewpoint of resolution and adhesion.

[0025] The (meth)acrylic acid aryl ester unit is a structural unit derived from a (meth)acrylic acid aryl ester. Examples of the (meth)acrylic acid aryl ester include benzyl (meth)acrylate, phenyl (meth)acrylate, and naphthyl (meth)acrylate. When the polymer (a) has a (meth)acrylic acid aryl ester unit, the content of the (meth)acrylic acid aryl ester unit may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, and may be 40% by mass or less, 35% by mass or less, 30% by mass or less, or 25% by mass or less, based on the total amount of the monomer units constituting the polymer (a), from the viewpoint of resolution and adhesion.

[0026] The hydroxyalkyl (meth)acrylate unit is a structural unit derived from a hydroxyalkyl (meth)acrylate. Examples of the hydroxyalkyl (meth)acrylate include hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, and hydroxyhexyl (meth)acrylate. When the alkyl moiety in the hydroxyalkyl (meth)acrylate unit has 3 or more carbon atoms, the hydroxyalkyl (meth)acrylate unit may have a branched structure.

[0027] When the polymer (a) has a hydroxyalkyl (meth)acrylate unit, the content of the hydroxyalkyl (meth)acrylate unit may be 0.5% by mass or more, 0.75% by mass or more, or 1.0% by mass or more, based on the total amount of monomer units constituting the polymer (a), from the viewpoint of dispersibility, and may be 20% by mass or less, 15% by mass or less, or 8% by mass or less, from the viewpoint of water absorbency.

[0028] In order to further improve the resolution and adhesion of the photosensitive resin composition, the polymer (a) may have a structural unit derived from styrene or a styrene derivative (hereinafter also referred to as a "styrene-based unit"). Examples of the styrene derivative include vinyltoluene, α-methylstyrene, p-methylstyrene, and p-ethylstyrene.

[0029] When the polymer (a) has a styrene-based unit, the content of the styrene-based unit, based on the total amount of monomer units constituting the polymer (a), may be 35% by mass or more, 40% by mass or more, 43% by mass or more, or 45% by mass or more from the viewpoint of resolution, and may be 70% by mass or less, 60% by mass or less, 50% by mass or less, or 48% by mass or less from the viewpoint of developability.

[0030] The polymer (a) may further have structural units derived from other monomers than those mentioned above. Examples of other monomers include acrylonitrile, vinyl alcohol ethers such as vinyl n-butyl ether, 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.

[0031] The component (A) may contain a binder polymer other than the polymer (a), or may consist solely of the polymer (a). From the viewpoints of adhesion and resolution, the content of the polymer (a) in the component (A) may be 50 to 100 mass % or 80 to 100 mass % based on the total amount of the component (A).

[0032] The acid value of polymer (a) may be 100 mgKOH / g or more, 120 mgKOH / g or more, 140 mgKOH / g or more, 150 mgKOH / g or more, 160 mgKOH / g or more, or 170 mgKOH / g or more from the viewpoint of developability, and 250 mgKOH / g or less, 240 mgKOH / g or less, 230 mgKOH / g or less, 200 mgKOH / g or less, or 190 mgKOH / g or less from the viewpoint of adhesion (developer resistance) of the cured product of the photosensitive resin composition. The acid value of polymer (a) can be adjusted by the content of structural units (e.g., (meth)acrylic acid units) constituting polymer (a). When component (A) contains a binder polymer other than polymer (a), the acid value of the other binder polymer may also be within the above range.

[0033] The weight average molecular weight (Mw) of the polymer (a) may be 10,000 or more, 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, 40,000 or more, or 45,000 or more from the viewpoint of adhesion (developer resistance) of the cured product of the photosensitive resin composition and ease of forming a thick film resist pattern, and may be 100,000 or less, 80,000 or less, 60,000 or less, or 50,000 or less from the viewpoint of developability. The dispersity (Mw / Mn) of the polymer (a) may be, for example, 1.0 or more or 1.5 or more, and may be 3.0 or less or 2.5 or less from the viewpoint of adhesion and resolution. When the (A) component contains a binder polymer other than the polymer (a), the Mw of the other binder polymer may also be within the above range.

[0034] The weight average molecular weight and dispersity can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. More specifically, they can be measured under the conditions described in the Examples. For compounds with low molecular weights, if it is difficult to measure the weight average molecular weight using the above-mentioned method, the molecular weight can be measured by another method and the average can be calculated.

[0035] The content of the component (A), based on the total amount of solids in the photosensitive resin composition, may be 20% by mass or more, 30% by mass or more, or 40% by mass or more from the viewpoint of film formability, and may be 90% by mass or less, 80% by mass or less, 70% by mass or less, or 65% by mass or less from the viewpoint of sensitivity and resolution.

[0036] The content of the (A) component may be 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 film formability, and may be 70 parts by mass or less, 65 parts by mass or less, or 60 parts by mass or less, from the viewpoint of sensitivity and resolution.

[0037] (Component (B): Photopolymerizable Compound) From the viewpoint of releasability, the photosensitive resin composition contains, as the component (B), a monofunctional (meth)acrylate having a bicyclo skeleton (hereinafter also referred to as “component (b1)”), and from the viewpoints of adhesion and resolution, the content of component (b1) is less than 5.0 parts by mass per 100 parts by mass of the total amount of component (A) and component (B).

[0038] Examples of the component (b1) include dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate.

[0039] From the viewpoint of achieving a balance between adhesion, resolution, and releasability, the content of the component (b1) may be 1.0 to 4.5 parts by mass, 1.5 to 4.0 parts by mass, 2.0 to 3.5 parts by mass, or 2.5 to 3.3 parts by mass per 100 parts by mass of the total amount of the components (A) and (B).

[0040] From the viewpoints of developability, resolution, and removability, the component (B) may contain a bifunctional (meth)acrylate (hereinafter also referred to as “component (b2)”), which is a compound having two (meth)acryloyl groups. Examples of the component (b2) include bisphenol A-type (meth)acrylates such as 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; polyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and EO-modified polypropylene glycol di(meth)acrylate; and di(meth)acrylates having an alicyclic skeleton such as cyclohexyl di(meth)acrylate and tricyclodecane dimethanol di(meth)acrylate.

[0041] As the component (b2), from the viewpoint of further improving resolution and releasability, bisphenol A type (meth)acrylate is preferred, and 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is more preferred.

[0042] From the viewpoint of further improving resolution and adhesion, the content of the component (b2) may be 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, or 35 parts by mass or more, and may be 65 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, or 45 parts by mass or less, relative to 100 parts by mass of the total amount of the components (A) and (B). That is, the content of the component (b2) may be 20 to 65 parts by mass, 25 to 60 parts by mass, 30 to 50 parts by mass, or 35 to 45 parts by mass, relative to 100 parts by mass of the total amount of the components (A) and (B).

[0043] From the viewpoints of sensitivity, developability, and adhesion, the component (B) may further contain a compound having three or more (meth)acryloyl groups (hereinafter also referred to as the “component (b3)”). Examples of the component (b3) 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, EO-modified dipentaerythritol hexa(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate.

[0044] The content of the (b3) component may be 1 mass % or more, 5 mass % or more, or 10 mass % or more, and may be 25 mass % or less, 20 mass % or less, or 15 mass % or less, based on the total amount of the (B) component.

[0045] The photosensitive resin composition may further contain, as the component (B), a photopolymerizable compound other than the above-mentioned components (b1), (b2), and (b3).

[0046] Examples of other photopolymerizable compounds include urethane monomers, nonylphenoxy polyethyleneoxy (meth)acrylates, 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 removability, the other photopolymerizable compound may be at least one selected from the group consisting of urethane monomers, nonylphenoxy polyethyleneoxy (meth)acrylates, and phthalic acid compounds.

[0047] Examples of nonylphenoxy polyethyleneoxy(meth)acrylates include nonylphenoxytriethyleneoxy(meth)acrylate, nonylphenoxytetraethyleneoxy(meth)acrylate, nonylphenoxypentaethyleneoxy(meth)acrylate, nonylphenoxyhexaethyleneoxy(meth)acrylate, nonylphenoxyheptaethyleneoxy(meth)acrylate, nonylphenoxyoctaethyleneoxy(meth)acrylate, nonylphenoxynonaethyleneoxy(meth)acrylate, nonylphenoxydecaethyleneoxy(meth)acrylate, and nonylphenoxyundecaethyleneoxy(meth)acrylate.

[0048] 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.

[0049] 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 viewpoints 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.

[0050] (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.

[0051] 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.

[0052] Component (C) may contain a hexaarylbiimidazole compound from the viewpoint of improving the adhesion of the photosensitive layer to a smooth substrate. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. A hydrogen atom bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (e.g., a chlorine atom).

[0053] The hexaarylbiimidazole compound may be a 2,4,5-triarylimidazole dimer, such as 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.

[0054] The content of component (C) may be 1.0 to 10 parts by mass, 2.0 to 8 parts by mass, 3.0 to 7.0 parts by mass, or 4.0 to 6.0 parts by mass, relative to 100 parts by mass of the total amount of component (A) and component (B). When the content of component (C) is within this range, it becomes easy to improve both photosensitivity and resolution in a balanced manner.

[0055] (Component (D): Sensitizer) The photosensitive resin composition according to this embodiment contains the component (D), which allows effective use of the absorption wavelength of actinic rays used for exposure.

[0056] Examples of the 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. From the viewpoint of further improving resolution and adhesion, the component (D) may contain an anthracene compound.

[0057] Examples of the anthracene compound include 9,10-dibutoxyanthracene, 9,10-diphenylanthracene, and 9,10-diethoxyanthracene. From the viewpoints of sensitivity, adhesion, resolution, and strippability, the anthracene compound may include 9,10-dibutoxyanthracene.

[0058] From the viewpoint of improving sensitivity and resolution, the content of the component (D) may be 0.2 parts by mass or more, 0.3 parts by mass or more, 0.4 parts by mass or more, or 0.5 parts by mass or more, and may be 1.5 parts by mass or less, 1.0 parts by mass or less, 0.8 parts by mass or less, 0.75 parts by mass or less, or 0.7 parts by mass or less, relative to 100 parts by mass of the total amount of the component (A) and the component (B).

[0059] (Other Components) The photosensitive resin composition may further contain one or more other components in addition to the components described above. Examples of other components include polymerization inhibitors, hydrogen donors (such as bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leucocrystal violet, and N-phenylglycine), dyes (such as malachite green), tribromophenyl sulfone, photocoloring agents, thermal color-developing inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, and thermal crosslinking agents. The content of the 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, relative to 100 parts by mass of the total amount of component (A) and component (B).

[0060] The photosensitive resin composition may contain an organic solvent to improve the handleability of the photosensitive composition and to adjust the viscosity and storage stability. Any commonly used organic solvent can be used as the organic solvent without any particular limitations. Examples of the organic solvent include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, and propylene glycol monomethyl ether. For example, components (A) to (D) can be dissolved in an organic solvent to form a solution with a solids content of approximately 30 to 60% by mass.

[0061] The photosensitive resin composition according to the present embodiment may be in a liquid form or a film form (photosensitive film). The photosensitive resin composition may be used, for example, as a negative photosensitive resin composition. The photosensitive resin composition may be suitably used in the method for forming a resist pattern and the method for manufacturing a wiring board, which will be described later.

[0062] [Photosensitive Element] The photosensitive element of this embodiment includes a support and a photosensitive layer formed on the support, and the photosensitive layer contains the above-described photosensitive resin composition. The content of each component (components (A) to (D) and other components) other than the volatile substance in the photosensitive layer may be within the numerical range of the content of each component in the above-described photosensitive resin composition. When using the photosensitive element of this embodiment, after laminating the photosensitive layer on a substrate, exposure may be performed without peeling off the support (support film).

[0063] Fig. 1 is a schematic cross-sectional view of a photosensitive element according to one embodiment. As shown in Fig. 1, the photosensitive element 1 includes a support 2, a photosensitive layer 3 formed on the support 2 and made from the photosensitive resin composition, and other layers such as a protective layer 4 that may be provided as needed.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The photosensitive layer 3 is made of the photosensitive resin composition described above. 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 to 100 μm. From the viewpoint of forming a resist pattern having a high aspect ratio, the thickness of the photosensitive layer may be 30 μm or more, 35 μm or more, 38 μm or more, 40 μm or more, or 50 μm or more, and from the viewpoint of releasability, the thickness may be 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, or 60 μm or less.

[0069] 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.

[0070] 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.

[0071] The photosensitive element may further include an intermediate layer between the support 2 and the photosensitive layer 3. The intermediate layer may be a layer containing a water-soluble resin. Examples of the water-soluble resin include a resin containing polyvinyl alcohol as a main component.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] [Method for forming a resist pattern] The method for forming a resist pattern of this embodiment includes a step of forming a photosensitive layer on a substrate using the photosensitive resin composition or the photosensitive element (photosensitive layer formation step), 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 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 for forming a resist pattern can also be referred to as a method for producing a substrate with a resist pattern.

[0076] (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 consisting of a substrate, a photosensitive layer, and a support, which are sequentially stacked, is obtained. 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.

[0077] The surface roughness (Ra) of the substrate may be 200 nm or less, 180 nm or less, or 160 nm or less from the viewpoint of suppressing halation due to unevenness on the substrate and improving resolution, and may be 10 nm or more, 30 nm or more, or 40 nm or more from the viewpoint of improving adhesion of the resist pattern. Ra may be 10 to 200 nm, 30 to 180 nm, or 40 to 160 nm from the viewpoint of maintaining a balance between resolution and adhesion.

[0078] 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). ２These 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.

[0079] (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.

[0080] 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.

[0081] 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.

[0082] (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. If a support is present on the photosensitive layer, the support is removed, and then the area other than the cured portion (also referred to as the unexposed portion) is removed (developed). There are two development methods: wet development and dry development, with wet development being widely used.

[0083] 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 puddle method, a spray method, brushing, scrubbing, and swinging immersion. From the viewpoint of improving resolution, a high-pressure spray method may be used as the development method. Development may also be carried out by combining two or more of these methods.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] [Method for manufacturing wiring board] The method for manufacturing a wiring board of 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-mentioned method for forming a resist pattern, and may also include other steps such as a resist pattern removal step, as necessary.

[0091] In the etching process, a resist pattern formed on a substrate is used as a mask to etch away the conductive layer provided on the substrate, thereby forming 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] 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.

[0093] After the etching or plating process, the resist pattern on the substrate is removed. The resist pattern can be removed, for example, using an inorganic alkaline stripper or an organic alkaline stripper. Examples of inorganic alkaline stripper solutions that can be used include a 1 to 10 mass % aqueous solution of sodium hydroxide and a 1 to 10 mass % aqueous solution of potassium hydroxide. Examples of organic alkaline stripper solutions that can be used include amine-based strippers such as ethanolamine, ethylenediamine, and diethylenetriamine, and tetramethylammonium hydroxide aqueous solutions. From the viewpoint of the strippability of thick-film resist patterns, organic alkaline stripper solutions may also be used.

[0094] Methods for removing the resist pattern include, for example, a dipping method and a spray method, which may be used alone or in combination.

[0095] 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.

[0096] The method for manufacturing a wiring board according to this embodiment can be applied to the manufacture of not only single-layer wiring boards but also multi-layer wiring boards, and can also be applied to the manufacture of wiring boards having small-diameter through holes.

[0097] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples.

[0098] [Photosensitive Resin Composition] Each photosensitive resin composition was prepared by mixing the components shown in Table 1 in the amounts (parts by mass) shown in the table. The amounts (parts by mass) of components other than the solvent shown in Table 1 are the mass of non-volatile components (solid content). Details of each component shown in Table 1 are as follows.

[0099] (Component (A)) A-1: ​​ethylene glycol monomethyl ether / toluene solution (solid content: 47% by mass) of a copolymer of methacrylic acid / methyl methacrylate / styrene / benzyl methacrylate (mass ratio: 27 / 5 / 45 / 23, Mw: 47,000, acid value: 176.1 mg KOH / g, Tg: 107°C) (Component (B)) b1-1: dicyclopentanyl acrylate (manufactured by Resonac Corporation, trade name "FA-513AS") b1-2: dicyclopentanyl methacrylate (manufactured by Resonac Corporation, trade name "FA-513M") b1-3: isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Ltd.) b2-1: 70% solution of 2,2-bis(4-(methacryloxyethoxy)phenyl)propane (average 10 mol adduct of ethylene oxide) in propylene glycol monomethyl ether (manufactured by Resonac Corporation, trade name "FA-321M") b2-2: tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-DCP") b2-3: ethoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "A-BPE-10") (component (C)) BCIM: 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole (manufactured by Hampford Chemical Industries, Ltd.) (component (D)) DBA: 9,10-dibutoxyanthracene (manufactured by Kawasaki Chemical Industries, Ltd.) (other components) Hydrogen donor: Leuco Crystal Violet (Yamada Chemical Industry Co., Ltd.) Dye: Malachite Green (Osaka Organic Chemical Industry Co., Ltd.)

[0100] [Photosensitive element] A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "FB-40") was prepared as a support. The photosensitive resin composition was applied to 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 of 40 μm after drying. A polyethylene film (manufactured by Tamapoly Corporation, product name "NF-15") was laminated on the 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.

[0101] [Laminate L1] A copper-clad laminate (manufactured by Resonac Corporation, product name "MCL-E-67") comprising a glass epoxy material and copper foil (thickness: 16 μm) arranged on both sides thereof was pickled, washed with water, and then dried with an air flow. The copper-clad laminate was then heated to 80°C, and the protective layer was peeled off. A photosensitive element was then laminated onto the copper-clad laminate so that the photosensitive layer was in contact with the copper surface, thereby obtaining a laminate L1 comprising, in order, the copper-clad laminate, the photosensitive layer, and the support. Lamination was performed using a 110°C heat roll at a pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0102] [Laminate L2] The above-mentioned photosensitive element was laminated onto a Cu-sputtered PET film (manufactured by Geomatec Co., Ltd., thickness: 125 μm) while peeling off the protective layer, so that the photosensitive layer was in contact with the copper surface, thereby obtaining a laminate L2 having the Cu-sputtered PET film, photosensitive layer, and support in that order. The lamination was performed using a heat roll at 110°C, with a compression pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0103] [Evaluation] The laminates L1 and L2 were evaluated as follows. The results are shown in Table 2.

[0104] (Minimum Development Time) The laminate L1 was cut into a square (5 cm x 5 cm) and the support was peeled off to obtain a test piece. Next, the unexposed photosensitive layer of the test piece was spray-developed at a pressure of 0.18 MPa using a 1% by mass aqueous sodium carbonate solution at 30°C, and the shortest time at which it was visually confirmed that 1 mm or more of the unexposed photosensitive layer had been removed was defined as the minimum development time (MD). 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 (unit: seconds), the better the developability.

[0105] (Sensitivity) After placing a Hitachi 41-step step tablet on the support of the laminate L1, the photosensitive layer was exposed through the support using a direct imaging exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name "FDi-Ms") using a blue-violet laser diode with a wavelength of 405 nm as a light source, at an exposure amount (amount of irradiation energy) such that the number of remaining steps of the Hitachi 41-step step tablet was 15. The exposure amount at this time (unit: mJ / cm ２ The sensitivity (photosensitivity) was evaluated by the following formula: The lower the exposure amount, the higher the sensitivity.

[0106] (Adhesion) Using a drawing pattern in which line width (L) / space width (S) is x / 3x (x=3 to 30, unit: μm, 1 μm intervals), the photosensitive layer of the laminate L1 was exposed with a direct writing exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15.

[0107] (Resolution) Using a drawing pattern in which the line width (L) / space width (S) ratio was 3x / x (x=3 to 30, unit: μm, 1 μm intervals), the photosensitive layer of the laminate L1 was exposed with a direct writing exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15.

[0108] After exposure, the support was peeled off from the laminate L1 to expose the photosensitive layer, and the unexposed areas were removed by spraying a 1% by mass aqueous sodium carbonate solution at 30°C for twice the minimum development time. After development, the space areas (unexposed areas) were removed without residue, and the line areas (exposed areas) were formed without meandering or chipping. Resolution was evaluated based on the minimum space width (unit: μm) in the resist pattern, and adhesion was evaluated based on the minimum line width (unit: μm) in the resist pattern. For both resolution and adhesion, the smaller the numerical value, the better the performance.

[0109] (Round hole resolution) Using a via pattern (via hole pattern) in which the diameter of the round hole opening / the center-to-center pitch of the round holes was x / 1.5x (x = 10 to 50, unit: μm, 1 μm intervals), the photosensitive layer of the laminate L2 was exposed with a direct imaging exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15.

[0110] After exposure, the support was peeled off from the laminate L2 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. The formed via pattern (via hole pattern) was observed under an optical microscope, and the round hole resolution was evaluated based on the value of 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 round hole resolution.

[0111] (Peeling property) Using a glass chrome type phototool (having a 45 mm × 60 mm planar pattern) as a negative for evaluating peeling test on the support of the laminate L1, the photosensitive layer was exposed through the support using a direct imaging exposure machine (FDi-Ms) at an exposure amount such that the number of remaining steps of a Hitachi 41-step step tablet was 15.

[0112] After exposure, the support was peeled off from the laminate L1 to expose the photosensitive layer, and the unexposed areas were removed by spraying a 1% by mass 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 a speed of 400 rpm. The time from the start of stirring until the cured film was completely removed from the substrate was defined as the peeling time (unit: seconds). A shorter peeling time indicates better releasability.

[0113]

[0114]

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

Claims

1. A photosensitive resin composition containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the photopolymerizable compound contains a monofunctional (meth)acrylate having a bicyclo skeleton, and the content of the monofunctional (meth)acrylate having a bicyclo skeleton is less than 5.0 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 monofunctional (meth)acrylate having a bicyclo skeleton is 1.0 to 4.5 parts by mass per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

3. The photosensitive resin composition according to claim 1, wherein the photopolymerizable compound further contains a bisphenol A type (meth)acrylate.

4. The photosensitive resin composition according to claim 1, wherein the sensitizer comprises an anthracene compound.

5. 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 4.

6. The photosensitive element of claim 5, wherein the photosensitive layer has a thickness of 30 μm or greater.

7. 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; 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.

8. A method for manufacturing a 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 claim 7, to form a conductor pattern.

9. The method for manufacturing a wiring board according to claim 8, further comprising the step of removing the resist pattern using an organic alkaline stripping solution after the etching or plating process.

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