WO2019173966A1

WO2019173966A1 - Photosensitizer, photosensitive resin composition, photosensitive element, and method of producing wiring board

Info

Publication number: WO2019173966A1
Application number: PCT/CN2018/078834
Authority: WO
Inventors: Sadaaki Katou; Xuesong Jiang; Yasuharu Murakami
Original assignee: Hitachi Chemical Company, Ltd.; Shanghai Jiao Tong University
Priority date: 2018-03-13
Filing date: 2018-03-13
Publication date: 2019-09-19
Also published as: JP2021523245A; JP7058335B2

Abstract

Provided is a photosensitizer containing a compound represented by the formula (1) : wherein A represents an aromatic hydrocarbon ring, X represents a monovalent organic group, R represents a monovalent hydrocarbon group, m1 represents an integer of 1 or greater, and n1 represents an integer of 0 or greater.

Description

PHOTOSENSITIZER, PHOTOSENSITIVE RESIN COMPOSITION, PHOTOSENSITIVE ELEMENT, AND METHOD OF PRODUCING WIRING BOARD

Technical Field

The present invention relates to a photosensitizer, a photosensitive resin composition, a photosensitive element, and a method of producing a wiring board.

Background Art

In wiring board production, a resist pattern is formed for obtaining a desired wiring pattern. Photosensitive resin compositions are widely used in resist patterning. In recent years, MSAP (Modified Semi Additive Process) has received attention as a promising method for forming a fine wiring pattern. It is required that a resist pattern is formed with a high accuracy compared to conventional methods to obtain a fine wiring pattern by this method.

A photosensitizer is typically added to a photosensitive resin composition for resist patterning with a high accuracy. For example, 9, 10-dibutoxyanthracene (DBA) is known as the photosensitizer (see Patent Document 1, for example) .

Citation List

Patent Literature

International Publication No. WO 2007/123062

Summary of Invention

Technical Problem

However, photosensitive resin compositions containing DBA have some room for improvement to obtain a resist pattern with an even higher accuracy. Additionally, a photosensitive resin composition is used typically in a form of a photosensitive element interposed between polymer films such as polyethylene films. According to studies conducted by the inventors of the present invention, DBA contained in a photosensitive resin composition penetrates polymer films and thereby may interfere with the formation of a desired resist pattern. This problem occurs especially when the polymer films are polyethylene films.

A primary object of the present invention is to provide a photosensitive resin composition and a photosensitive element which are capable of forming a resist pattern with a high accuracy and inhibiting penetration of a photosensitizer into a polyethylene film; and a photosensitizer suitable for use in the photosensitive resin composition and the photosensitive element.

Solution to Problem

An aspect of the present invention is a photosensitizer containing a compound represented by the formula (1) :

wherein A represents an aromatic hydrocarbon ring, X represents a monovalent organic group, R represents a monovalent hydrocarbon group, m1 represents an integer of 1 or greater, and n1 represents an integer of 0 or greater.

Another aspect of the present invention is a photosensitive resin composition containing a resin, a photopolymerizable compound, a photopolymerization initiator, and a compound represented by the formula (1) .

In the formula (1) , the aromatic hydrocarbon ring may be a fused ring comprising two or more rings, may be a fused ring consisting of two to four rings, and may be an anthracene ring.

The compound represented by the formula (1) may be a compound represented by the formula (3a) :

wherein X ¹ and X ² independently represent a monovalent organic group, R represents a monovalent hydrocarbon group, and n3 represents an integer of 0 to 8.

In the formula (3a) , the monovalent organic group may be a monovalent hydrocarbon group. The monovalent hydrocarbon group may be an alkyl group and may be an aryl group. The monovalent organic group may have a hydroxyl group, an ester group or an ether group.

Another aspect of the present invention is a photosensitive element that includes a support and a photosensitive resin layer, the photosensitive resin layer being disposed on the support and comprising the photosensitive resin composition. The photosensitive element may further include a protective layer disposed on the photosensitive resin layer on a side opposite to the support.

Another aspect of the present invention is a method of producing a wiring board, the method including disposing a photosensitive resin layer comprising the photosensitive resin composition on a substrate; photocuring a part of the photosensitive resin layer; removing an uncured part of the photosensitive resin layer to form a resist pattern; and forming a wiring layer on a part of the substrate on which no resist pattern is formed.

Advantageous Effects of Invention

The present invention provides a photosensitive resin composition and a photosensitive element which are capable of forming a resist pattern with a high accuracy and inhibiting penetration of a photosensitizer into a polyethylene film; and a photosensitizer suitable for use in the photosensitive resin composition and the photosensitive element.

Brief Description of Drawings

Fig. 1 is a schematic sectional view of a photosensitive element according to an embodiment.

Fig. 2 is a scheme view of a method of producing a wiring board according to an embodiment.

Description of Embodiments

Embodiments of the present invention will be described below in detail.

The term “step” in the present specification refers to an independent step; as well as a step that successfully achieves the intended action of the step and is not clearly differentiated from other steps. A numerical range specified using the word “to” refers to a range that includes the numerical values preceding and following the word “to” as the minimum and the maximum values of the range. The term “layer” refers to a structure that is formed all over the surface of something in a plan view as well as a structure that is formed on a partial surface of something in a plan view. The term “ (meth) acrylic acid” refers to at least one of “acrylic acid” and corresponding “methacrylic acid” . The same applies to other similar expressions such as (meth) acrylate.

The term “ (poly) oxyethylene group” in the present specification refers to an oxyethylene group or a polyoxyethylene group having two or more ethylene groups linked to each other with an ether bond. The term “ (poly) oxypropylene group” refers to an oxypropylene group or a polyoxypropylene group having two or more propylene groups linked to each other with an ether bond. The term “EO-modified” is used to refer to a compound having a (poly) oxyethylene group. The term “PO-modified” is used to refer to a compound having a (poly) oxypropylene group. The term “EO·PO-modified” is used to refer to a compound having a (poly) oxyethylene group and/or a (poly) oxypropylene group.

In the present specification, a content of each component in a composition in the present specification, when there are a plurality of substances contained in the composition that consist the component, refers to the total content of all of these substances in the composition unless otherwise indicated. In the present specification, the term “solid component” refers to nonvolatile component in a photosensitive resin composition, not including volatile substances (water or solvent, for example) . More specifically, the term “solid component” refers to any component that is not solvent and that does not volatilize but remains after drying a photosensitive resin composition which is described below, and includes a substance that is in a liquid state, a syrup-like state, or a wax state at room temperature (25℃) .

A photosensitive resin composition according to an embodiment contains component (A) , which is a resin, component (B) , which is a photopolymerizable compound, component (C) , which is a photopolymerization initiator, and component (D) , which is a compound represented by the following formula (1) :

The photosensitive resin composition contains one, or, two or more types of the component (A) . Examples of the component (A) include acrylic resins, styrene resins, epoxy resins, amide resins, amide epoxy resins, alkyd resins, and phenolic resins. The component (A) may contain an acrylic resin from the viewpoint of further improvement in alkaline development properties.

The acrylic resin has a structural unit derived from (meth) acrylic acid, for example, and may further have a structural unit derived from other monomers except (meth) acrylic acid.

That other monomer may be a (meth) acrylic acid ester, for example. Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl esters, (meth) acrylic acid cycloalkyl esters, and (meth) acrylic acid aryl esters.

That other monomer may be preferably a (meth) acrylic acid alkyl ester from the viewpoint of improvement in alkaline development properties and peeling properties. The alkyl group in the (meth) acrylic acid alkyl ester may be, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, or a structural isomer of any of these groups. The alkyl group may be a C1 to C4 alkyl group from the viewpoint of further improvement in peeling properties.

When that other monomer is a (meth) acrylic acid alkyl ester, the content of the (meth) acrylic acid alkyl ester based on the total content of monomers constituting the component (A) may be 1%by mass or more, 2%by mass or more, or 3%by mass or more from the viewpoint of excellent peeling properties, and may be 80%by mass or less, 60%by mass or less, or 50%by mass or less from the viewpoint of further improvement in resolution and adhesion.

That other monomer may be styrene or a styrene derivative from the viewpoint of further improvement in accuracy and adhesion. The styrene derivative may be vinyltoluene or α-methylstyrene, for example. When that other monomer is styrene or a styrene derivative, the content of the styrene and the styrene derivative based on the total content of monomers constituting the component (A) may be 5%by mass or more, 10%by mass or more, or 20%by mass or more from the viewpoint of further improvement in resolution, and may be 65%by mass or less, 55%by mass or less, or 50%by mass or less from the viewpoint of excellent peeling properties.

The acid value of the component (A) may be 100 mgKOH/g or more, 120 mgKOH/g or more, 140 mgKOH/g or more, or 150 mgKOH/g or more from the viewpoint of excellent development, and may be 250 mgKOH/g or less, 240 mgKOH/g or less, or 230 mgKOH/g or less from the viewpoint of improvement in adhesion (or resistance to developer solution) of a cured product derived from the photosensitive resin composition. The acid value of the component (A) is adjustable by changing the content of a structural unit constituting the component (A) (for example, the content of a structural unit derived from (meth) acrylic acid) .

The weight average molecular weight (Mw) of the component (A) may be 10000 or more, 20000 or more, or 25000 or more from the viewpoint of excellent adhesion (or resistance to developer solution) of a cured product derived from the photosensitive resin composition, and may be 100000 or less, 80000 or less, or 60000 or less from the viewpoint of excellent development. The degree of dispersion (Mw/Mn) of the component (A) may be 1.0 or more or 1.5 or more, for example, and from the viewpoint of further improvement in adhesion and resolution, the degree of dispersion may be 3.0 or less or 2.5 or less.

The weight average molecular weight and the degree of dispersion may be measured by, for example, gel permeation chromatography (GPC) and use of a calibration curve plotted for standard polystyrene. More specifically, the measurement may be carried out under conditions described in the Examples section. When a compound with a low molecular weight is subjected to measurement and it is difficult to measure the weight average molecular weight by the method described above, the weight average molecular weight of the compound may be determined by measuring the molecular weight of the compound by a different method and then calculating the average value.

The content of the component (A) based on the total content of solid component 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 excellent film formation, and may be 90%by mass or less, 80%by mass or less, or 65%by mass or less from the viewpoint of further excellent sensitivity and further excellent resolution.

The content of the component (A) based on 100 parts by mass of the total content of the component (A) and the component (B) may be 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more from the viewpoint of excellent film formation, 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 further improvement in sensitivity and resolution.

The photosensitive resin composition contains one, or, two or more types of the component (B) . The component (B) may be any compound that polymerizes in response to light and may be, for example, a compound having an ethylenically unsaturated bond. The component (B) may contain a bisphenol A (meth) acrylate compound from the viewpoint of further improvement in alkaline development properties, resolution, and post-curing peeling properties.

Examples of the bisphenol A (meth) acrylate compound include 2, 2-bis (4- ( (meth) acryloxypolyethoxy) phenyl) propane (such as 2, 2-bis (4- ( (meth) acryloxypentaethoxy) phenyl) propane) , 2, 2-bis (4- ( (meth) acryloxypolypropoxy) phenyl) propane, 2, 2-bis (4- ( (meth) acryloxypolyb utoxy) phenyl) propane, and 2, 2-bis (4- ( (meth) acryloxypolyethoxypolypropoxy) phenyl) propane. The component (B) may contain 2, 2-bis (4- ( (meth) acryloxypolyethoxy) phenyl) propane (such as 2, 2-bis (4- ( (meth) acryloxypentaethoxy) phenyl) propane) from the viewpoint of further improvement in resolution and peeling properties.

The content of the bisphenol A (meth) acrylate compound based on the total content of the component (B) may be 20%by mass or more or 40%by mass or more and may be 100%by mass or less, 95%by mass or less, or 90%by mass or less from the viewpoint of further improvement in resist patterning resolution.

The component (B) may contain an α, β-unsaturated ester compound obtained by reaction between a polyhydric alcohol and an α, β-unsaturated carboxylic acid from the viewpoint of further proper improvement in resolution and flexibility. Examples of the α, β-unsaturated ester compound include polyalkylene glycol di (meth) acrylates such as polyethylene glycol di(meth) acrylate, polypropylene glycol di (meth) acrylate, and EO-modified polypropylene glycol, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO·PO-modified trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, and tetramethylolmethane tetra (meth) acrylate.

The component (B) may contain trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, or EO·PO-modified trimethylolpropane tri (meth) acrylate from the viewpoint of further improvement in resolution, .

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

The photosensitive resin composition may contain, as the component (B) , other photopolymerizable compounds that are neither the bisphenol A (meth) acrylate compound nor the α, β-unsaturated ester compound.

Examples of that other photopolymerizable compound include nonylphenoxypolyethyleneoxy acrylate, phthalic compounds, (meth) acrylic acid alkyl esters, and photopolymerizable compounds having at least one cationically polymerizable cyclic ether group within the molecule (such as oxetane compounds) . That other photopolymerizable compound may be at least one compound selected from the group consisting of nonylphenoxypolyethyleneoxy acrylate and phthalic compounds from the viewpoint of further proper improvement in resolution, adhesion, resist shape, and post-curing peeling properties.

Examples of the nonylphenoxypolyethyleneoxy acrylates include nonylphenoxytriethyleneoxy acrylate, nonylphenoxytetraethyleneoxy acrylate, nonylphenoxypentaethyleneoxy acrylate, nonylphenoxyhexaethyleneoxy acrylate, nonylphenoxyheptaethyleneoxy acrylate, nonylphenoxyoctaethyleneoxy acrylate, nonylphenoxynonaethyleneoxy acrylate, nonylphenoxydecaethyleneoxy acrylate, and nonylphenoxyundecaethyleneoxy acrylate.

The phthalic compounds may be, for example, γ-chloro-β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate (also called 3-chloro-2-hydroxypropyl-2- (meth) acryloyloxyethylphthalate) , β-hydroxyethyl-β’- (meth) acryloyloxyethyl-o-phthalate, or β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate, preferably γ-chloro-β-hydroxypropyl-β’- (meth) acryloyloxyethyl-o-phthalate.

When the component (B) contains that other photopolymerizable compound, the content of that other photopolymerizable compound based on the total content of the component (B) may be 1%by mass or more, 3%by mass or more, or 5%by mass or more and 30%by mass or less, 25%by mass or less, or 20%by mass or less from the viewpoint of further proper improvement in resolution, adhesion, resist shape, and post-curing peeling properties.

The content of the component (B) based on the total content of solid component in the photosensitive resin composition may be 3%by mass or more, 10%by mass or more, or 25%by mass or more from the viewpoint of further improvement in 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 excellent film formation.

The photosensitive resin composition contains one, or, two or more types of the component (C) . Examples of the component (C) include hexaarylbiimidazole compounds; aromatic ketones 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; quinones such as alkyl anthraquinones; benzoin ether compounds such as benzoin alkyl ethers; benzoin compounds such as benzoin and alkyl benzoins; benzyl derivatives such as benzyl dimethyl ketal; bis (2, 4, 6-trimethylbenzoyl) -phenylphosphineoxide; bis (2, 6-dimethylbenzoyl) -2, 4, 4-trimethyl-pentylphosphineoxide; and (2, 4, 6-trimethylbenzoyl) ethoxyphenylphosphineoxide.

The component (C) may contain a hexaarylbiimidazole compound from the viewpoint of further inhibiting penetration of a photosensitizer into a polyethylene film. An aryl group in the hexaarylbiimidazole compound may be a phenyl group, for example. A hydrogen atom bonded to an aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (such as a chlorine atom) .

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

The content of the hexaarylbiimidazole compound based on the total content of the component (C) may be 90%by mass or more, 95%by mass or more, or 99%by mass or more from the viewpoint of further inhibiting penetration of a photosensitizer into a polyethylene film. The component (C) may be consisting of the hexaarylbiimidazole compound.

The content of the component (C) based on the total content of solid component in the photosensitive resin composition may be 0.1%by mass or more, 0.5%by mass or more, or 1%by mass or more and 20%by mass or less, 10%by mass or less, or 5%by mas or less from the viewpoint of further improvement in sensitivity and adhesion.

The photosensitive resin composition contains one, or, two or more types of the component (D) . The component (D) is used as a photosensitizer. More specifically, in an embodiment, the photosensitizer contains a compound represented by the following formula (1) :

wherein A represents an aromatic hydrocarbon ring, X represents a monovalent organic group, R represents a monovalent hydrocarbon group, m1 represents an integer of 1 or greater, and n1 represents an integer of 0 or greater; when m1 is an integer of 2 or greater, a plurality of monovalent organic groups represented by X may be the same as or different from each other; and when n1 is an integer of 2 or greater, a plurality of monovalent hydrocarbon groups represented by R may be the same as or different from each other.

The aromatic hydrocarbon ring represented by A may contain only one ring or may be a fused ring containing two or more rings. The aromatic hydrocarbon ring is preferably a fused ring containing two or more rings, more preferably a fused ring containing two to four rings, further preferably a fused ring containing three rings (an anthracene ring) from the viewpoint of absorption of light that has a wavelength within an appropriate range.

The monovalent organic group represented by X may be a monovalent hydrocarbon group, for example. The monovalent hydrocarbon group may be an alkyl group or an aryl group. The monovalent organic group represented by X may have a hydroxyl group, an alkoxy group, an aldehyde group, an ester group, an ether group, an amino group, or a nitro group; may have a hydroxyl group, an ester group, or an ether group; may be a substituted monovalent hydrocarbon group that is equivalent to the monovalent hydrocarbon group in which at least one hydrogen atom is substituted with a hydroxyl group, an alkoxy group, an aldehyde group, an ester group, an amino group, or a nitro group; or may be a substituted (or an ether-group-containing) monovalent hydrocarbon group that is equivalent to the monovalent hydrocarbon group in which at least one methylene group (-CH ₂-) is substituted with an oxygen atom (-O-) . The monovalent organic group represented by X is preferably a monovalent hydrocarbon group, a substituted monovalent hydrocarbon group that is equivalent to the monovalent hydrocarbon group in which at least one hydrogen atom is substituted with a hydroxyl group or an ester group, or a substituted (or an ether-group-containing) monovalent hydrocarbon group that is equivalent to the monovalent hydrocarbon group in which at least one methylene group (-CH ₂-) is substituted with an oxygen atom (-O-) ; and more preferably a substituted monovalent hydrocarbon group that is equivalent to the monovalent hydrocarbon group in which at least one hydrogen atom is substituted with a hydroxyl group from the viewpoint of excellent solubility in the photosensitive resin composition.

The number of carbon atoms in the monovalent organic group represented by X may be 1 or greater, 2 or greater, or 3 or greater; may be 12 or smaller, 10 or smaller, 8 or smaller, or 6 or smaller; and may be 1 to 12, 1 to 10, 1 to 8, 1 to 6, 2 to 12, 2 to 10, 2 to 8, 2 to 6, 3 to 12, 3 to 10, 3 to 8, or 3 to 6.

The monovalent hydrocarbon group represented by R may be an alkyl group, for example. The number of carbon atoms in the monovalent hydrocarbon group may be 1 to 8, 1 to 6, or 1 to 4, for example.

m1 may be an integer of 2 or greater; may be an integer of 6 or smaller, 5 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 6, 2 to 5, 2 to 4, or 2 to 3.

n1 may be an integer of 1 or greater or 2 or greater; may be an integer of 8 or smaller, 6 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 0 to 8, 0 to 6, 0 to 4, 0 to 3, 0 to 2, 1 to 8, 1 to 6, 1 to 4, 1 to 3, 1 to 2, 2 to 8, 2 to 6, 2 to 4, or 2 to 3.

In an embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (1a) , (1b) , (1c) , or (1d) :

wherein each of R ^a, R ^c and R ^d represents a monovalent hydrocarbon group, R ^b represents a hydrocarbon group with a valence of (p + 1) , p represents an integer of 1 or greater, and A, R, m1, and n1 represent the same A, R, m1, and n1, respectively, as in the formula (1) .

The monovalent hydrocarbon group represented by R ^a may be an alkyl group or an aryl group, for example. The number of carbon atoms in the monovalent hydrocarbon group may be 1 or greater, 2 or greater, or 3 or greater; may be 12 or smaller, 10 or smaller, 8 or smaller, or 6 or smaller; and may be 1 to 12, 1 to 10, 1 to 8, 1 to 6, 2 to 12, 2 to 10, 2 to 8, 2 to 6, 3 to 12, 3 to 10, 3 to 8, or 3 to 6.

The number of carbon atoms in the hydrocarbon group with a valence of (p + 1) represented by R ^b may be 1 or greater, 2 or greater, or 3 or greater; may be 12 or smaller, 10 or smaller, 8 or smaller, or 6 or smaller; and may be 1 to 12, 1 to 10, 1 to 8, 1 to 6, 2 to 12, 2 to 10, 2 to 8, 2 to 6, 3 to 12, 3 to 10, 3 to 8, or 3 to 6.

The monovalent hydrocarbon group represented by R ^c or R ^d may be an alkyl group or an aryl group, for example. The number of carbon atoms in the monovalent hydrocarbon group may be 1 or greater, 2 or greater, or 3 or greater; may be 12 or smaller, 10 or smaller, 8 or smaller, or 6 or smaller; and may be 1 to 12, 1 to 10, 1 to 8, 1 to 6, 2 to 12, 2 to 10, 2 to 8, 2 to 6, 3 to 12, 3 to 10, 3 to 8, or 3 to 6.

p may be an integer of 2 or greater; may be an integer of 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 1 to 4, 1 to 3, 1 to 2, 2 to 4, or 2 to 3.

In an embodiment, the compound represented by the formula (1) may be a compound represented by the following formula (2) , (3) , or (4) :

wherein m2, m3, and m4 independently represent an integer of 1 or greater, n2, n3, and n4 independently represent an integer of 0 or greater, and X and R represent the same X and R, respectively, as in the formula (1) ; when m2, m3, or m4 is an integer of 2 or greater, a plurality of monovalent organic groups represented by X may be the same as or different from each other; and when n2, n3, or n4 is an integer of 2 or greater, a plurality of monovalent hydrocarbon groups represented by R may be the same as or different from each other.

m2 may be an integer of 2 or greater; may be an integer of 6 or smaller, 5 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 6, 2 to 5, 2 to 4, or 2 to 3. n2 may be an integer of 1 or greater or 2 or greater; may be an integer of 6 or smaller, 5 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 0 to 6, 0 to 5, 0 to 4, 0 to 3, 0 to 2, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 6, 2 to 5, 2 to 4, or 2 to 3. Here, (m2 + n2) is 8 or smaller.

m3 may be an integer of 2 or greater; may be an integer of 6 or smaller, 5 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; may be an integer of 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 6, 2 to 5, 2 to 4, or 2 to 3. n3 may be an integer of 1 or greater or 2 or greater; may be an integer of 8 or smaller, 6 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 0 to 8, 0 to 6, 0 to 4, 0 to 3, 0 to 2, 1 to 8, 1 to 6, 1 to 4, 1 to 3, 1 to 2, 2 to 8, 2 to 6, 2 to 4, or 2 to 3. Here, (m3 + n3) is 10 or smaller.

m4 may be an integer of 2 or greater; may be an integer of 6 or smaller, 5 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, 2 to 6, 2 to 5, 2 to 4, or 2 to 3. n4 may be an integer of 1 or greater or 2 or greater; may be an integer of 8 or smaller, 6 or smaller, 4 or smaller, 3 or smaller, or 2 or smaller; and may be an integer of 0 to 8, 0 to 6, 0 to 4, 0 to 3, 0 to 2, 1 to 8, 1 to 6, 1 to 4, 1 to 3, 1 to 2, 2 to 8, 2 to 6, 2 to 4, or 2 to 3. Here, (m4 + n4) is 10 or smaller.

The compound represented by the formula (1) is preferably a compound represented by the formula (3) from the viewpoint of absorption of light having a wavelength within a more appropriate range. In an embodiment, the compound represented by the formula (3) may be a compound represented by the following formula (3a) . In an embodiment, the compound represented by the formula (3a) may be a compound represented by the following formula (3b) (acompound represented by the formula (3a) in which n3 = 0) :

wherein X ¹ and X ² independently represent the same X as in the formula (3) , preferably the same to each other. R and n3 represent the same R and n3, respectively, as in the formula (3) .

In an embodiment, the compound represented by the formula (3a) may be a compound represented by the following formula (3a-1) , (3a-2) , (3a-3) , or (3a-4) . In an embodiment, the compound represented by the formula (3b) may be a compound represented by the following formula (3b-1) , (3b-2) , (3b-3) , or (3b-4) .

In these formulae, R ^1a and R ^2a independently represent the same R ^a as in the formula (1a) , preferably the same to each other. R ^1b and R ^2b independently represent the same R ^b as in the formulae (1b) to (1d) , preferably the same to each other. R ^1c and R ^2c independently represent the same R ^c as in the formula (1c) , preferably the same to each other. R ^1d and R ^2d independently represent the same R ^d as in the formula (1d) , preferably the same to each other. p1 and p2 independently represent the same p as in the formulae (1b) to (1d) , preferably the same to each other. R and n3 represent the same R and n3, respectively, as in the formula (3a) .

The content of the component (D) based on 100 parts by mass of the total content of the component (A) and the component (B) is 0.01 parts by mass or more, for example, preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, further preferably 0.3 parts by mass from the viewpoint of obtaining a desired level of sensitivity; and is 10 parts by mass or less, for example, preferably 5 parts by mass or less, more preferably 3 parts by mass or less, further preferably 2 parts by mass or less, particularly preferably 1 part by mass or less from the viewpoint of further improvement in patterning accuracy.

The mass ratio of the content of the component (D) to the content of the component (C) (content of the component (D) /content of the component (C) ) may be 0.025 or more, 0.1 or more, or 0.15 or more and may be 1.0 or less, 0.5 or less, or 0.3 or less, from the viewpoint of further inhibiting penetration of a photosensitizer into a polyethylene film.

The photosensitive resin composition may further contain a known photosensitizer as an additional photosensitizer, in addition to the component (D) . The content of the additional sensitizer based on 100 parts by mass of the total content of the component (A) and the component (B) may be, for example, 0.01 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more; and may be 10 parts by mass or less, 5 parts by mass or less, 3 parts by mass or less, 2 parts by mass or less, 1 part by mass or less, or 0.9 parts by mass or less.

The photosensitive resin composition may further contain component (E) , which is a polymerization inhibitor, from the viewpoint of inhibiting polymerization at an unexposed portion during resist patterning and thereby further improving resolution. The polymerization inhibitor may be t-butylcatechol or 4-hydroxy-2, 2, 6, 6-tetramethylpiperidin-N-oxyl, for example.

The photosensitive resin composition that contains the component (D) rather than a conventional photosensitizer (DBA, for example) can inhibit polymerization at an unexposed portion during resist patterning and further improve the accuracy of resist patterning, even when the photosensitive resin composition contains no polymerization inhibitor. Therefore, the content of the component (E) based on 100 parts by mass of the total content of the component (A) and the component (B) may be 0.01 parts by mass or less, 0.005 parts by mass or less, or 0.003 parts by mass or less, or the photosensitive resin composition may contain no component (E) . The content of the component (E) based on 100 parts by mass of the total content of the component (A) and the component (B) may be 0.001 parts by mass or more.

The photosensitive resin composition may further contain one, or, two or more additional components other than any of the components described above. Examples of these additional components include a hydrogen donor (such as bis [4- (dimethylamino) phenyl] methane, bis [4- (diethylamino) phenyl] methane, leuco crystal violet, and N-phenylglycine) , a dye (such as malachite green) , tribromophenyl sulfone, a photochromic agent, an agent for preventing thermochromic phenomena, a plasticizer (such as p-toluenesulfonamide) , a pigment, a filler, an antifoaming agent, a flame retardant, a stabilizer, an adhesion promoter, a leveling agent, a peeling promoter, an antioxidant, a perfume, an imaging agent, and a thermal crosslinking agent. The content of the additional components based on 100 parts by mass of the total content of the component (A) and the component (B) 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.

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

The photosensitive resin composition may be suitable for use in resist patterning and may be particularly suitable for use in a method of producing a wiring board described below.

Fig. 1 is a schematic sectional view of a photosensitive element according to an embodiment. As shown in Fig. 1, a photosensitive element 1 includes a support 2, a photosensitive resin layer 3 disposed on the support 2, and a protective layer 4 disposed on the photosensitive resin layer 3 on a side opposite to the support 2.

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

These polymer films may be commercially available as, for example, polyethylene terephthalate films such as the PS product line (PS-25, for example) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by Tamapoly Co., Ltd., polypropylene films manufactured by Oji Paper Co., Ltd. (Alphan MA-410 and E-200C, for example) , and polypropylene films manufactured by Shin-Etsu Film Co., Ltd.

The thickness of the support 2 may be 1 μm or more or 5 μm or more from the viewpoint of inhibiting potential damage caused to the support 2 while the support 2 is peeled off the photosensitive resin layer 3; and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of proper exposure through the support 2.

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 inhibiting potential damage caused to the protective layer 4 while the protective layer 4 is peeled off and the photosensitive resin layer 3 and the support 2 are laminated with a substrate; and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improvement in productivity.

The photosensitive resin layer 3 is constituted of the photosensitive resin composition described above. The thickness of the photosensitive resin layer 3 after drying (or after organic solvent volatilization when the photosensitive resin composition contains an organic solvent) may be 1 μm or more or 5 μm or more from the viewpoint of easy application and improved productivity; and may be 100 μm or less, 50 μm or less, or 40 μm or less from the viewpoint of further improvement in adhesion and resolution.

The photosensitive element 1 may be obtained as follows, for example. First, the photosensitive resin layer 3 is formed on the support 2. The formation of the photosensitive resin layer 3 may be carried out by, for example, applying a photosensitive resin composition containing an organic solvent to form a coating layer and drying the resulting coating layer. Subsequently, the protective layer 4 is formed on the photosensitive resin layer 3 on a side opposite to the support 2.

The formation of the coating layer may be carried out by, for example, a known method, such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating. The coating layer is dried in such a way that the amount of the organic solvent remaining in the photosensitive resin layer 3 becomes 2%by mass or less, for example. More specifically, the drying is carried out at 70℃ to 150℃ for about 5 minutes to 30 minutes, for example.

In another embodiment, the photosensitive element may include no protective layer and may further include an additional layer such as a cushioning layer, an adhesive layer, a light-absorbing layer, and a gas barrier layer.

The photosensitive element 1 may be, for example, a photosensitive element sheet or a photosensitive element roll that is a roll of the photosensitive element wound around a core. When the photosensitive element 1 is such a photosensitive element roll, it is preferable that the support 2 be on the outside. The core is made of polyethylene, polypropylene, polystyrene, polyvinyl chloride, or an acrylonitrile-butadiene-styrene copolymer, for example. An end face of the photosensitive element roll may have an end-face separator disposed thereon from the viewpoint of protecting the end face and may have a moisture-proof end-face separator disposed thereon from the viewpoint of avoiding edge fusion. The photosensitive element 1 may be wrapped with a black sheet having low moisture permeability, for example.

The photosensitive element 1 may be suitable for use in resist patterning, particularly suitable for use in a method of producing a wiring board described below. The photosensitive element 1 is capable of inhibiting penetration of a photosensitizer into a polyethylene film compared to a conventional photosensitive element, and therefore at least one of the support 2 and the protective layer 4 can be constituted of a polyethylene film, or can be constituted of the hydrocarbon-based polymer film having a low density or the stretch film thereof.

Fig. 2 is a scheme view showing a method of producing a wiring board (also called printed wiring board) according to an embodiment. In this method, as shown in Fig. 2 (a) , a substrate (for example, a substrate on which a circuit is to be formed) is prepared in which the substrate has an insulating layer 11 and a conductor layer 12 formed on the insulating layer 11. The conductor layer 12 may be a metal copper layer, for example.

Subsequently, as shown in Fig. 2 (b) , a photosensitive resin layer 13 is formed on the substrate (conductor layer 12) . In this step, the photosensitive resin layer 13 consisting of the photosensitive resin composition described above is formed on the substrate (conductor layer 12) by using the photosensitive resin composition described above or the photosensitive element 1. For example, the formation of the photosensitive resin layer 13 is carried out by applying the photosensitive resin composition to the substrate and drying the photosensitive resin composition. Alternatively, the formation of the photosensitive resin layer 13 is carried out by removing the protective layer 4 from the photosensitive element 1 and then heating the photosensitive resin layer 3 of the photosensitive element 1 for thermocompression bonding to the substrate. During the thermocompression bonding, at least one of the photosensitive resin layer 3 and the substrate may be heated at 70℃ to 130℃, for example. The pressure applied in the thermocompression bonding may be 0.1 MPa to 1.0 MPa, for example.

Subsequently, as shown in Fig. 2 (c) , a mask 14 is placed on the photosensitive resin layer 13 and an active ray 15 is applied thereto. As a result, an area other than the area with the mask 14 placed thereon is subjected to exposure and thereby the photosensitive resin layer 13 is photocured. The light source of the active ray 15 may be an ultraviolet light source or a visible light source, such as a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser (an argon laser, for example) , a solid-state laser (aYAG laser, for example) , or a semiconductor laser.

In another embodiment, instead of the mask 14, a direct image exposure method such as LDI exposure method or DLP exposure method may be used. In that case, the active ray 15 may be applied in a desired pattern so that only a part of the photosensitive resin layer 13 is exposed to light.

Subsequently, as shown in Fig. 2 (d) , an area (uncured part) other than a photocured part formed by exposure is removed from the substrate by development and thereby a resist pattern 16 consisting of the photocured part (the cured product of the photosensitive resin layer) is formed. The method of development may be wet development or dry development, for example, preferably wet development.

Wet development is carried out by using a developer solution applicable to the photosensitive resin composition and by such a technique as dipping, using a paddle, spraying, brushing, slapping, scrubbing, or dipping and shaking. The developer solution is selected as appropriate depending on the composition of the photosensitive resin composition and may be an alkaline developer solution or an organic solvent developer solution.

The alkaline developer solution may be an aqueous solution containing such a base as an alkali hydroxide, such as a hydroxide of lithium, sodium, or potassium; an alkali carbonate, such as a carbonate or a bicarbonate of lithium, sodium, potassium, or ammonium; an alkali metal phosphate, such as potassium phosphate or sodium phosphate; an alkali metal pyrophosphate, such as sodium pyrophosphate or potassium pyrophosphate; borax; sodium metasilicate; tetramethylammonium hydroxide; ethanolamine; ethylenediamine; diethylenetriamine; 2-amino-2-hydroxymethyl-1, 3-propanediol; 1, 3-diamino-2-propanol; or morpholine.

The alkaline developer solution may be, for example, an aqueous solution of sodium carbonate at 0.1%by mass to 5%by mass, an aqueous solution of potassium carbonate at 0.1%by mass to 5%by mass, an aqueous solution of sodium hydroxide at 0.1%by mass to 5%by mass, or an aqueous solution of sodium tetraborate at 0.1%by mass to 5%by mass. The alkaline developer solution may have pH9 to pH11, for example.

The alkaline developer solution may further contain a surfactant, an antifoaming agent, and/or an organic solvent, for example. Examples of the organic solvent include acetone, ethyl acetate, an alkoxyethanol having a C1 to C4 alkoxy group, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether. The content of the organic solvent based on the total amount of the alkaline developer solution may be 2%by mass to 90%by mass.

The organic solvent developer solution may contain an organic solvent such as 1, 1, 1-trichloroethane, N-methylpyrrolidone, N, N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, or γ-butyrolactone. The organic solvent developer solution may further contain 1%by mass to 20%by mass of water.

In this step, following the removal of the unexposed part, the resultant may be heated at 60℃ to 250℃ or subjected to further exposure at 0.2 J/cm ² to 10 J/cm ² as needed for further curing the resist pattern 16.

Subsequently, as shown in Fig. 2 (e) , the part of the conductor layer 12 on which the resist pattern 16 is not formed is subjected to plating treatment, for example, and thereby a wiring layer 17 is formed on that part. The type of material constituting the wiring layer 17 may be the same as or different from that of the conductor layer 12. Trace layer 17 may be a metal copper layer, for example. As the plating treatment, either or both of electrolytic plating treatment and electroless plating treatment may be employed.

Subsequently, as shown in Fig. 2 (f) , the resist pattern 16 is removed and a part of the conductor layer 12 disposed at a position corresponding to the resist pattern 16 is removed. As a result, a wiring board 18 is obtained which is constituted of the substrate and the wiring layer 17 formed on the substrate.

The removal of the resist pattern 16 may be carried out by, for example, development with the use of an aqueous solution of strong alkali by such a technique as dipping or spraying. The aqueous solution of strong alkali may be an aqueous solution of sodium hydroxide at 1%by mass to 10%by mass or an aqueous solution of potassium hydroxide at 1%by mass to 10%by mass, for example.

The removal of the conductor layer 12 may be carried out by etching treatment. The etchant liquid is selected as appropriate depending on the type of the conductor layer 12 and may be a cupric chloride solution, a ferric chloride solution, an alkaline etchant solution, or a hydrogen peroxide etchant liquid, for example.

Examples

Next, the present invention is further more specifically described referring to examples. These examples are by no means limitative of the scope of the present invention.

(Acrylic resin A-1)

Monomers, specifically 150 g of methacrylic acid, 25 g of methyl methacrylate, 200 g of styrene, and 125 g of benzyl methacrylate; and 2.0 g of azobisisobutyronitrile were mixed to prepare solution (a) . In 50 g of mixed liquid (x) of 30 parts by mass of methyl cellosolve and 20 parts by mass of toluene, 3.0 g of azobisisobutyronitrile was dissolved, and thus solution (b) was prepared. To a flask equipped with a stirrer, a reflux condenser, a thermometer, a tap funnel, and a nitrogen-gas inlet tube, 500 g of the mixed liquid (x) was added. The mixed liquid was stirred while nitrogen gas was being blown into the flask, and the temperature was raised to reach 80℃. To the mixed liquid in the flask, the solution (a) was added dropwise over 4 hours at a constant rate. Then, stirring was carried out for 2 hours at 80℃. Subsequently, to the solution in the flask, the solution (b) was added dropwise over 10 minutes at a constant rate. Then, the resulting solution in the flask was stirred at 80℃ for 3 hours. The temperature of the solution in the flask was raised to reach 90℃ over 30 minutes, and this temperature (90℃) was kept for 2 hours. Stirring was terminated and the resultant was cooled to room temperature (25℃) . Thus, a solution of acrylic resin A-2 was obtained. The solution of acrylic resin A-2 had a content of nonvolatile matter (solid component) of 48.0%by mass, a weight average molecular weight of 47000, and an acid value of 176 mgKOH/g.

(Acrylic resin A-2)

To a flask equipped with a reflux condenser, a thermometer, a tap funnel, and a nitrogen-gas inlet tube, 400 g of the mixed liquid (x) was added. While nitrogen gas was being blown into the flask and the mixed liquid (x) was being heated to 80℃, stirring the mixed liquid was carried out. Meanwhile, 125 g of methacrylic acid, 250 g of methyl methacrylate, which were monomers, and 125 g of styrene were mixed with 0.8 g of azobisisobutyronitrile to prepare solution (c) . To the mixed liquid (x) heated to 80℃, the solution (c) was added dropwise over 4 hours. The temperature of the resultant was kept at 80℃ for 2 hours with stirring. To the solution in the flask, another solution prepared by dissolving 1 g of azobisisobutyronitrile in 100 g of solution (c) was added dropwise over 10 minutes at a constant rate. Then, the resulting solution in the flask was stirred at 80℃ for 3 hours. The temperature of the solution in the flask was raised to reach 90℃ over 30 minutes, and this temperature (90℃) was kept for 2 hours, followed by cooling. Thus, a solution of acrylic resin A-2 was obtained.

Acetone was added to the resulting solution of acrylic resin A-2 so that the content of a nonvolatile component (nonvolatile matter) reached 50%by mass. The resulting binder polymer had a weight average molecular weight of 60000 and an acid value of 176 mgKOH/g.

The weight average molecular weight was measured by gel permeation chromatography (GPC) and calculated based on a calibration curve plotted for standard polystyrene. GPC conditions are as follows.

(GPC conditions)

Pump: Hitachi L-6000 (trade name, manufactured by Hitachi, Ltd. )

Columns: Three columns shown below

Gelpack GL-R420

Gelpack GL-R430

Gelpack GL-R440 (trade names, all of these were manufactured by Hitachi Chemical Company, Ltd. )

Eluent: Tetrahydrofuran

Measurement temperature: 40℃

Flow rate: 2.05 mL/minute

Detector: Hitachi L-3300 RI (trade name, manufactured by Hitachi, Ltd. )

Components shown in Tables 1-3 each in the amount (parts by mass) shown in Tables 1-3 were mixed, and thus photosensitive resin compositions were prepared. Each amount (parts by mass) of the component (A) shown in Tables 1-3 is the mass of nonvolatile component (amount of solid component) . Details of each component shown in Tables 1-3 are as follows.

Component (B)

B-1: 2, 2-Bis (4- (methacryloxypentaethoxy) phenyl) propane [FA-321M (trade name, manufactured by Hitachi Chemical Company, Ltd. ) ]

B-2: EO-Modified polypropylene glycol #700 dimethacrylate [FA-023M (trade name, manufactured by Hitachi Chemical Company, Ltd. ) ]

B-3: γ-Chloro-β-hydroxypropyl-β’-methacryloyloxyethyl-o-phthalate [FA-MECH (trade name, manufactured by Hitachi Chemical Company, Ltd. ) ]

B-4: EO-Modified trimethylolpropane methacrylate [FA-137M (trade name, manufactured by Hitachi Chemical Company, Ltd. ) ]

B-5: Polyethylene glycol #400 dimethacrylate [9G (trade name, manufactured by Shin Nakamura Chemical Co., Ltd. ) ]

B-6: Trimethylolpropane EO-modified triacrylate [M3130 (trade name, manufactured by Toyo Chemicals Co., Ltd. ) ]

Component (C)

C-1: 2, 2-Bis (o-chlorophenyl) -4, 5-4’, 5’-tetraphenyl-1, 2’-biimidazole [B-CIM (trade name, manufactured by Hampford) ]

Component (D)

D-1: Compound represented by the following formula (D-1)

D-2: Compound represented by the following formula (D-2)

D-3: Compound represented by the following formula (D-3)

D-4: Compound represented by the following formula (D-4)

D-5: Compound represented by the following formula (D-5)

d-1: 9, 10-Dibutoxyanthracene (the following formula (d-1) )

Component (E)

E-1: 4-t-Butylcatechol [DIC-TBC (trade name, manufactured by DIC Corporation) ] (Other additives)

F-1: Leuco crystal violet [LCV (trade name, manufactured by Yamada Chemical Co., Ltd. ) ]

F-2: Mixture of 1H-benzotriazolecarboxylic acid, 5-amino-1H-tetrazole, beef tallow alkyl trimethylenediamine, di (2-ethylhexyl) amine, and methoxypropanol [SF-808H (trade name, manufactured by Sunlight Co., Ltd. ) ]

F-3: N-Phenylglycine [NPG (trade name, manufactured by Wako Pure Chemical Industries, Ltd. )

As a support, a polyethylene terephthalate film (manufactured by Teijin Limited, trade name “HTF-01” ) with a thickness of 16 μm was prepared. A photosensitive resin composition was applied to the support to form a coating with a uniform thickness, and the resultant was dried in a hot-air convection dryer sequentially at 70℃ and then at 110℃. Thus, a photosensitive resin layer with a dry thickness of 25 μm was formed. To the photosensitive resin layer, a polyethylene film (manufactured by Tamapoly Co., Ltd., trade name “NF-15” ) as a protective layer was bonded, and thus a photosensitive element having the support, the photosensitive resin layer, and the protective layer sequentially laminated was obtained.

A copper-clad laminate (substrate, manufactured by Hitachi Chemical Company, Ltd. trade name “MCL-E-679” ) , which was a glass epoxy material having copper foil (thickness, 35 μm) laminated on both sides, was subjected to surface treatment with a surface roughening liquid, “MECetchBOND CZ-8100” (trade name, manufactured by MEC Company Ltd. ) . The resultant was rinsed with water, acid, and water, followed by air stream drying. To the resulting surface-treated copper-clad laminate warmed to 80℃, the photosensitive element was laminated while the protective layer was being peeled off, in such a way that the photosensitive resin layer came into contact with the copper surface. Thus, a laminate having the copper-clad laminate, the photosensitive resin layer, and the support laminated in this order was obtained. The resulting laminate was used as a specimen in the following test. The lamination process was carried out with rolls heated at 110℃ under conditions of a press pressure of 0.4 MPa and a roll speed of 1.5 m/minute.

(Evaluation of patterning accuracy)

On the photosensitive resin layer of the specimen, a 41-step tablet (manufactured by Hitachi Chemical Company, Ltd. ) was placed. Then, exposure was carried out with a DLP exposure machine (manufactured by Via Mechanics, Ltd., trade name “DE-1UH” ) equipped with a semiconductor laser as a light source and operated at a wavelength of 405 nm in accordance with imaging data having a wiring pattern, which was a pattern for evaluation, having a (line width) / (space width) value of n/n (n = 3 μm to 20 μm; 2 μm to 2.5 μm intervals) . The exposure was carried out at a dose that was adjusted so that the 41-step tablet had 14.0 steps remaining after development. Then, the support was peeled off and the uncured parts were removed by spraying an aqueous solution of sodium carbonate at 1.0%by mass for 60 seconds to form a resist pattern. The formed resist pattern was subjected to optical microscopic examination and the line width of the resist pattern was measured. Smaller difference L, which is a difference between the measured line width of the resist pattern and the line width of the wiring pattern of the imaging data (i.e., L = the measured line width -the line width of the wiring pattern) means that the resist pattern was formed with a higher accuracy. Tables 1-3 show the results of evaluation based on the following criteria:

A: L is less than 1.0 μm

B: L is 1.0 μm or more but less than 1.5 μm

C: L is 1.5 μm or more but less than 3.0 μm

D: L is 3.0 μm or more

E: The resist pattern was entirely peeled off due to lack of sensitivity

(Evaluation of photosensitizer penetration into polyethylene film)

A new polyethylene terephthalate film and a new polyethylene film were prepared in the same manner as those used in fabricating the photosensitive element described above.

The polyethylene film was peeled from the photosensitive element fabricated as described above, and the remaining polyethylene terephthalate film attached to the photosensitive resin layer was placed on a sample measurer of a UV spectrometer (manufactured by Hitachi, Ltd. ; tradename: “U-3310” ) . Furthermore, the new polyethylene terephthalate film was placed on a reference measurer of the UV spectrometer. Absorbance was measured, and an absorbance Ix at a wavelength (λmax) in which absorbance was at its greatest in the wavelength range of 350-450 nm was measured.

Subsequently, the polyethylene film peeled as described above was placed on the sample measurer of the UV spectrometer, and the new polyethylene film was placed on the reference measurer. Absorbance was measured, and an absorbance Iy at a wavelength (λmax) in which absorbance was at its greatest in the wavelength range of 350-450 nm was measured.

The permeation rate of photosensitizer into the polyethylene film (PE) was calculated from the measured absorbances Ix and Iy in accordance with the following formula:

Permeation rate into PE (%) = Iy/Ix×100

Tables 1-3 show the results of evaluation based on the following criteria:

A: Permeation rate into PE is less than 1%

B: Permeation rate into PE is 1%or more but less than 5%

C: Permeation rate into PE is 5%or more

[Table 1]

[Table 2]

[Table 3]

Reference Signs List

1... photosensitive element, 2... support, 3, 13... photosensitive resin layer, 4... protective layer, 16... resist pattern, 17... wiring layer, 18... wiring board

Claims

A photosensitizer comprising a compound represented by the following formula (1) :

wherein A represents an aromatic hydrocarbon ring, X represents a monovalent organic group, R represents a monovalent hydrocarbon group, m1 represents an integer of 1 or greater, and n1 represents an integer of 0 or greater.
The photosensitizer according to claim 1, wherein the aromatic hydrocarbon ring is a fused ring comprising two or more rings.
The photosensitizer according to claim 1 or 2, wherein the aromatic hydrocarbon ring is a fused ring comprising two to four rings.
The photosensitizer according to any one of claims 1 to 3, wherein the aromatic hydrocarbon ring is an anthracene ring.
The photosensitizer according to any one of claims 1 to 4, wherein the compound represented by the formula (1) is a compound represented by the following formula (3a) :

wherein X ¹ and X ² independently represent a monovalent organic group, R represents a monovalent hydrocarbon group, and n3 represents an integer of 0 to 8.
The photosensitizer according to claim 5, wherein the monovalent organic group is a monovalent hydrocarbon group.
The photosensitizer according to claim 6, wherein the monovalent hydrocarbon group is an alkyl group.
The photosensitizer according to claim 6, wherein the monovalent hydrocarbon group is an aryl group.
The photosensitizer according to claim 5, wherein the monovalent organic group has a hydroxyl group, an ester group or an ether group.
A photosensitive resin composition comprising:

a resin;

a photopolymerizable compound;

a photopolymerization initiator; and

a compound represented by the following formula (1) :

wherein A represents an aromatic hydrocarbon ring, X represents a monovalent organic group, R represents a monovalent hydrocarbon group, m1 represents an integer of 1 or greater, and n1 represents an integer of 0 or greater.
The photosensitive resin composition according to claim 10, wherein the aromatic hydrocarbon ring is a fused ring comprising two or more rings.
The photosensitive resin composition according to claim 10 or 11, wherein the aromatic hydrocarbon ring is a fused ring comprising two to four rings.
The photosensitive resin composition according to any one of claims 10 to 12, wherein the aromatic hydrocarbon ring is an anthracene ring.
The photosensitive resin composition according to any one of claims 10 to 13, wherein the compound represented by the formula (1) is a compound represented by the following formula (3a) :

wherein X ¹ and X ² independently represent a monovalent organic group, R represents a monovalent hydrocarbon group, and n3 represents an integer of 0 to 8.
The photosensitive resin composition according to claim 14, wherein the monovalent organic group is a monovalent hydrocarbon group.
The photosensitive resin composition according to claim 15, wherein the monovalent hydrocarbon group is an alkyl group.
The photosensitive resin composition according to claim 15, wherein the monovalent hydrocarbon group is an aryl group.
The photosensitive resin composition according to claim 14, wherein the monovalent organic group has a hydroxyl group, an ester group or an ether group.
A photosensitive element comprising:

a support; and

a photosensitive resin layer disposed on the support, the photosensitive resin layer comprising the photosensitive resin composition according to any one of claims 10 to 18.
The photosensitive element according to claim 19, further comprising a protective layer disposed on the photosensitive resin layer on a side opposite to the support.
A method of producing a wiring board, comprising:

disposing a photosensitive resin layer comprising the photosensitive resin composition according to any one of claims 10 to 18 on a substrate;

photocuring a part of the photosensitive resin layer;

removing an uncured part of the photosensitive resin layer to form a resist pattern; and

forming a wiring layer on a part of the substrate on which no resist pattern is formed.