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

Abstract

A photosensitive resin composition containing a resin having an ethylenically unsaturated bond and an acidic group, a photopolymerizable compound, and a photopolymerization initiator having a fluorene skeleton, wherein the content of a polybutadiene-based elastomer is 0 to 2.0 mass% based on the total solid content of the photosensitive resin composition.

Description

Photosensitive resin composition, photosensitive element, printed circuit board, and method for manufacturing a printed circuit board

[0001] This disclosure relates to a photosensitive resin composition, a photosensitive element, a printed circuit board, and a method for manufacturing a printed circuit board.

[0002] In the field of printed circuit boards (PCBs), permanent resist is formed on the PCBs. Permanent resist plays a role in preventing corrosion of the conductor layer and maintaining electrical insulation between conductor layers during the use of the PCB. Furthermore, in processes such as flip-chip mounting and wire bonding mounting of semiconductor elements onto the PCB via solder, the permanent resist also acts as a solder resist film, preventing solder from adhering to unwanted areas of the conductor layer on the PCB.

[0003] In recent years, in response to the increasing density of printed circuit boards, the miniaturization of copper wiring and the narrowing of bump pitches have progressed, and further performance improvements are required for permanent resists (solder resists). In particular, the demand for the formation of fine patterns is increasing year by year.

[0004] Therefore, in order to meet the above requirements, the development of photosensitive resin compositions used for forming permanent resists is underway. For example, Patent Document 1 discloses a photocurable and thermosetting resin composition containing a specific active energy ray curable resin, a specific polybutadiene, a photopolymerization initiator, and a photosensitive (meth)acrylate compound.

[0005] Japanese Patent Publication No. 2002-293878

[0006] However, even with photosensitive resin compositions like the one described in Patent Document 1, there is still room for improvement in terms of resolution.

[0007] One aspect of this disclosure aims to provide a photosensitive resin composition capable of forming an insulating layer with excellent resolution, as well as a photosensitive element, a printed circuit board, and a method for manufacturing a printed circuit board using the photosensitive resin composition.

[0008] As a result of the inventors' investigation, it was first found that one of the causes of insufficient resolution was the polybutadiene-based elastomer contained in the photosensitive resin composition. Based on this finding, further investigation revealed that the above problem could be solved by limiting the content of the polybutadiene-based elastomer to a specific range and using a specific photopolymerization initiator.

[0009] In other words, one aspect of this disclosure provides the following photosensitive resin compositions, photosensitive elements, printed circuit boards, and methods for manufacturing printed circuit boards: [1] A photosensitive resin composition comprising a resin having ethylenically unsaturated bonds and acidic groups, a photopolymerizable compound, and a photopolymerization initiator having a fluorene skeleton, wherein the content of polybutadiene elastomer is 0 to 2.0% by mass based on the total solid content of the photosensitive resin composition. [2] The photosensitive resin composition according to [1], wherein the content of polyester elastomer is 0 to 1.4% by mass based on the total solid content of the photosensitive resin composition. [3] The photosensitive resin composition according to [1] or [2], further comprising at least one thermosetting resin selected from the group consisting of bisphenol F type epoxy resins and phenol novolac type epoxy resins. [4] The photosensitive resin composition according to any one of [1] to [3], wherein the photopolymerizable compound comprises dipentaerythritol hexa(meth)acrylate. [5] A photosensitive resin composition according to any one of [1] to [4], wherein the chlorine content is 250 ppm by mass or less. [6] A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer comprises the photosensitive resin composition according to any one of [1] to [5]. [7] A printed wiring board comprising an insulating layer containing a cured product of the photosensitive resin composition according to any one of [1] to [5]. [8] A method for manufacturing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of [1] to [5]; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form an insulating layer. [9] A method for manufacturing a printed wiring board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to [6]; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form an insulating layer.

[0010] According to this disclosure, a photosensitive resin composition capable of forming an insulating layer with excellent resolution, and a photosensitive element, a printed circuit board, and a method for manufacturing a printed circuit board using the photosensitive resin composition can be provided.

[0011] This is a schematic cross-sectional view showing a photosensitive element according to this embodiment. This is a schematic diagram showing one aspect of the manufacturing method of the printed circuit board according to this embodiment.

[0012] The present disclosure will be described in detail below. In this specification, the term "process" includes not only independent processes but also processes that are indistinguishable from other processes as long as the intended function of the process is achieved. The term "layer" includes not only structures that are formed over the entire surface when viewed in a plan view, but also structures that are formed in part.

[0013] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers listed before and after "~" 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 in one stage may be replaced with the upper or lower limit of a numerical range in another stage, or with the values ​​shown in the examples. In this specification, for example, the statement "10 or more" means 10 and numbers greater than 10, and the same applies when the numbers are different. Similarly, for example, the statement "10 or less" means 10 and numbers less than 10, and the same applies when the numbers are different.

[0014] In this specification, the content of each component in a composition means the total content of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component are present in the composition. In this specification, "number of ring members" means the number of carbon atoms required to form a ring, and does not include the number of carbon atoms of substituents on the ring. In this specification, "(meth)acrylate" means at least one of "acrylate" and its corresponding "methacrylate," and the same applies to other similar expressions such as (meth)acrylic acid. In this specification, "solids" refers to the non-volatile content of a photosensitive resin composition excluding volatile substances, and includes components that are liquid, syrup-like, or waxy at room temperature (around 25°C).

[0015] [Photosensitive Resin Composition] The photosensitive resin composition according to this embodiment contains (A) a resin having ethylenically unsaturated bonds and acidic groups (hereinafter sometimes referred to as "component (A)"), (B) a photopolymerizable compound resin (hereinafter sometimes referred to as "component (B)"), and (C) a photopolymerization initiator (hereinafter sometimes referred to as "component (C)"). The photopolymerization initiator includes a photopolymerization initiator having a fluorene skeleton. Furthermore, in the photosensitive resin composition, the content of polybutadiene elastomer is 0 to 2.0% by mass based on the total solid content of the photosensitive resin composition.

[0016] (Component (A): Resin having an ethylenically unsaturated bond and an acidic group) The photosensitive resin composition according to this embodiment includes a resin having an ethylenically unsaturated bond and an acidic group as component (A). The resin having an ethylenically unsaturated bond and an acidic group is not particularly limited as long as it has a photopolymerizable ethylenically unsaturated bond and an alkali-soluble acidic group. Examples of groups having an ethylenically unsaturated bond (hereinafter sometimes referred to as "ethylenically unsaturated group") include vinyl group, allyl group, propargyl group, butenyl group, ethynyl group, phenylethynyl group, maleimide group, nadiimide group, and (meth)acryloyl group, and among these, the (meth)acryloyl group is preferred from the viewpoint of excellent reactivity and resolution. Examples of acidic groups that component (A) has include carboxyl group, sulfo group, and phenolic hydroxyl group. Among these, the carboxyl group is preferred from the viewpoint of superior resolution.

[0017] Examples of resins having ethylenically unsaturated bonds and acidic groups include (A1) phenol derivatives having ethylenically unsaturated bonds and acidic groups (hereinafter sometimes referred to as "(A1) acid-modified ethylenically unsaturated bond-containing phenol derivative" or "(A1) component"). Component (A1) may be an oligomer or a polymer.

[0018] (A1) Acid-modified ethylenically unsaturated bond-containing phenol derivative (A1) Acid-modified ethylenically unsaturated bond-containing phenol derivative is a resin obtained by reacting (a1) a compound having two or more phenolic hydroxyl groups in one molecule (hereinafter sometimes referred to as "component (a1)") with (b1) an alkylene oxide (hereinafter sometimes referred to as "component (b1)") to obtain a resin (A1'), reacting (c1) an ethylenically unsaturated group-containing organic acid (hereinafter sometimes referred to as "component (c1)") to obtain a resin (A1''), and then reacting the resulting resin (A1'') with (d1) a saturated or unsaturated group-containing polybasic acid anhydride (hereinafter sometimes referred to as "component (d1)").

[0019] (a1) Compounds having two or more phenolic hydroxyl groups in one molecule. Examples of component (a1) include condensates of phenols and ketones, condensates of phenols and aldehydes, condensates of phenols and aromatic aldehydes having phenolic hydroxyl groups, poly-p-hydroxystyrene, naphthol-type novolac resins, trisphenolmethane-type resins, etc. These may be used individually or in combination of two or more. (a1) Examples of phenols used for the synthesis of component include phenols; cresols such as o-cresol, m-cresol, and p-cresol; xylenols such as 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, and 3,4-xylenol; monohydric phenols such as 1-naphthol and 2-naphthol; and polyhydric phenols such as resorcinol, alkylresorcinol, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene. These may be used individually or in combination of two or more.

[0020] Further, examples of the component (a1) include known phenol resins such as phenol novolac resins, alkyl novolac phenol resins, naphthol novolac resins, bisphenol A novolac resins, phenol aralkyl novolac resins, phenol naphthalene novolac resins, phenol dicyclopentadiene novolac resins, modified novolac phenol resins modified with cashew nut oil, terpenes, tall oil, rosin, phenoxy resins, xylene resins and the like, and resol-type phenol resins.

[0021] ((b1) alkylene oxide) Examples of the component (b1) include ethylene oxide, propylene oxide, trimethylene oxide, tetrahydrofuran, tetrahydropyran and the like.

[0022] The component (A1') obtained by reacting the component (a1) with the component (b1) has a (poly)oxyalkylene group having an alcoholic hydroxyl group at a terminal end, which is formed by a ring-opening addition reaction between the phenolic hydroxyl group of the component (a1) and the component (b1). The (poly)oxyalkylene group is chain-extended from part or all of the phenolic hydroxyl groups of the component (a1). The residual phenolic hydroxyl groups to which no (poly)oxyalkylene group is added in the component (A1') is preferably 0.2 equivalent or less relative to the phenolic hydroxyl groups of the component (a1).

[0023] The number of repeating oxyalkylene units constituting the (poly)oxyalkylene group in the component (A1') is preferably 1 to 10. If the number of repeating oxyalkylene units is less than 1, the photocurability of the photosensitive resin composition may be reduced. If the number of repeating oxyalkylene units is more than 10, the heat resistance, light resistance and thermosetting properties may be reduced.

[0024] By further reacting the component (A1') with the component (c1), the component (A1'') having an ethylenically unsaturated group introduced into the component (A1') can be obtained.

[0025] ((c1) Ethylenically unsaturated group-containing organic acid) As the component (c1), for example, acrylic acid, dimers of acrylic acid, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, α-cyanocinnamic acid and other acrylic acid derivatives; half-ester compounds which are reaction products of hydroxyl group-containing (meth)acrylate and dibasic acid anhydride; and half-ester compounds which are reaction products of monoglycidyl ether having an ethylenically unsaturated bond or monoglycidyl ester having an ethylenically unsaturated bond and a dibasic acid anhydride. Component (c1) may be used alone, or two or more types may be used in combination.

[0026] In the reaction between component (A1') and component (c1), it is preferable to carry out the reaction at a ratio where component (c1) is 0.2 to 0.8 equivalents relative to 1 equivalent of the alcoholic hydroxyl group of component (A1'), and it is more preferable to carry out the reaction at a ratio of 0.4 to 0.6 equivalents. By carrying out the reaction at such a ratio, photosensitivity increases, and a fine pattern tends to be obtained.

[0027] For the reaction between component (A1') and component (c1), a polymerization inhibitor may be used for the purpose of preventing polymerization during the reaction. Examples of the polymerization inhibitor include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, and phenothiazine. The polymerization inhibitor may be used alone, or two or more types may be used in combination.

[0028] By further reacting (d1) a polybasic acid anhydride containing a saturated group or an unsaturated group with component (A1''), which is a reaction product of component (A1') and component (c1), (A1) an acid-modified ethylenically unsaturated bond-containing phenol derivative can be obtained.

[0029] (d1) Polybasic acid anhydride containing saturated or unsaturated groups. Examples of component (d1) include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride. Among these, tetrahydrophthalic anhydride is preferred from the viewpoint of superior resolution. Component (d1) may be used alone or in combination of two or more.

[0030] In the reaction between component (A1'') and component (d1), it is preferable to react them in a ratio of 0.1 to 1.0 equivalents of component (d1) per equivalent of 1 equivalent of alcoholic hydroxyl group in component (A1''), and more preferably in a ratio of 0.2 to 0.8 equivalents. This allows for adjustment of the acid value of component (A1).

[0031] Furthermore, as a resin having ethylenically unsaturated bonds and acidic groups, (A2) epoxy derivatives having ethylenically unsaturated bonds and acidic groups (hereinafter sometimes referred to as "(A2) acid-modified ethylenically unsaturated bond-containing epoxy derivative" or "(A2) component") may be used. Component (A2) may be an oligomer or a polymer.

[0032] ((A2) Acid-modified ethylenically unsaturated bond-containing epoxy derivative) (A2) Acid-modified ethylenically unsaturated bond-containing epoxy derivative is a resin (A2') obtained by reacting (a2) epoxy resin (hereinafter sometimes referred to as "component (a2)") with (c2) organic acid containing ethylenically unsaturated groups (hereinafter sometimes referred to as "component (c2)") with (d2) polybasic acid anhydride containing saturated or unsaturated groups (hereinafter sometimes referred to as "component (d2)").

[0033] (a2) Epoxy resins. Examples of component (a2) include bisphenol novolac type epoxy resins, novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, triphenolmethane type epoxy resins, dicyclopentadiene type epoxy resins, and biphenyl type epoxy resins. From the viewpoint of superior resolution and superior crack resistance, component (a2) may also include bisphenol novolac type epoxy resins and novolac type epoxy resins.

[0034] Examples of commercially available bisphenol novolac type epoxy resins include EXA-7376 (manufactured by DIC Corporation, product name) and EPON SU8 (manufactured by Westlake, product name).

[0035] Examples of novolac-type epoxy resins include phenol novolac-type epoxy resins and cresol novolac-type epoxy resins.

[0036] Examples of commercially available phenol novolac type epoxy resins or cresol novolac type epoxy resins include YDCN-700-7, YDCN-700-10, YDCN-704, YDCN-704A, YDPN-638 (all manufactured by Nippon Steel Chemical & Material Co., Ltd., trade names), EOCN-102S, EOCN-103S, EOCN-104S, EOCN-1012, EOCN-1027, BREN-S (all manufactured by Nippon Kayaku Co., Ltd., trade names), and N-740, N-770, N-665, N-673 (all manufactured by DIC Corporation, trade names).

[0037] If necessary, hydrogenated bisphenol A epoxy resin may be partially used as component (a2), and styrene-maleic acid resins such as hydroxyethyl (meth)acrylate modified styrene-maleic anhydride copolymers may also be partially used.

[0038] Component (c2) and component (d2) can be the same compounds as those described above for component (c1) and component (d1). Component (c2) and component (d2) can each be used individually or in combination of two or more.

[0039] Component (A) preferably contains component (A1) from the viewpoint of suppressing the occurrence of undercuts, providing superior resolution, and improving the insulation reliability of the insulating layer. Furthermore, component (A) may also contain resins having ethylenically unsaturated bonds and acidic groups other than component (A1) (for example, component (A2)).

[0040] (A) The acid value of component (A) is not particularly limited. From the viewpoint of improving the solubility of the unexposed portion in the alkaline aqueous solution, the acid value of component (A) may be 30 mg KOH / g or more, 40 mg KOH / g or more, or 50 mg KOH / g or more. From the viewpoint of improving the electrical properties of the cured product, the acid value of component (A) may be 150 mg KOH / g or less, 120 mg KOH / g or less, or 100 mg KOH / g or less.

[0041] The weight-average molecular weight (Mw) of component (A) varies depending on the resin skeleton, but is not particularly limited. From the viewpoint of improving the adhesion of the insulating layer, the Mw of component (A) may be 3000 or more, 4000 or more, or 5000 or more. From the viewpoint of superior resolution, the Mw of component (A) may be 30000 or less, 25000 or less, or 18000 or less.

[0042] Mw can be measured by gel permeation chromatography (GPC). For example, Mw can be measured under the GPC conditions described below, and the value converted using a calibration curve for standard polystyrene can be used as the Mw value. A set of five samples ("PStQuick MP-H" and "PStQuick B," manufactured by Tosoh Corporation) can be used as the standard polystyrene to create the calibration curve. GPC instrument: High-speed GPC instrument "HCL-8320GPC" (manufactured by Tosoh Corporation) Detector: Differential refractometer or UV detector (manufactured by Tosoh Corporation) Column: TSKgel SuperMultipore HZ-H column (column length: 15 cm, column inner diameter: 4.6 mm) (manufactured by Tosoh Corporation) Eluent: Tetrahydrofuran (THF) Measurement temperature: 40°C Flow rate: 0.35 mL / min Sample concentration: 10 mg / THF 5 mL Injection volume: 20 μL

[0043] The content of component (A) in the photosensitive resin composition may be 20 to 70% by mass, 25 to 60% by mass, or 30 to 50% by mass, based on the total solid content of the photosensitive resin composition, from the viewpoint of improving the heat resistance, electrical properties, and chemical resistance of the insulating layer.

[0044] (Component (B): Photopolymerizable compound) Component (B) is not particularly limited as long as it is a compound having a functional group that exhibits photopolymerization. Component (B) may be a photopolymerizable compound having an ethylenically unsaturated group that does not have an acidic group. Component (B) preferably comprises at least one selected from the group consisting of (Bi) a monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group, (Bii) a difunctional vinyl monomer having two polymerizable ethylenically unsaturated groups, and (Biiii) a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups, and more preferably comprises at least the above-mentioned (Biiii) component. Components (Bi) to (Biiii) are preferably those with a molecular weight of 1000 or less.

[0045] ((Bi) Monofunctional vinyl monomer) Examples of monofunctional vinyl monomers having one polymerizable ethylenically unsaturated group include (meth)acrylic acid and alkyl (meth)acrylates. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and hydroxyethyl (meth)acrylate. The (Bi) component may be used alone or in combination of two or more.

[0046] ((Bii) Difunctional Vinyl Monomer) Examples of the above-mentioned difunctional vinyl monomer having two polymerizable ethylenically unsaturated groups include polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis(4-(meth)acryloxypolyethoxypolypropoxyphenyl)propane, bisphenol A diglycidyl ether di(meth)acrylate, and the like. The (Bii) component may be used alone or in combination of two or more.

[0047] ((Biiii) Polyfunctional vinyl monomer) Examples of polyfunctional vinyl monomers having at least three polymerizable ethylenically unsaturated groups include (meth)acrylate compounds having a trimethylolpropane-derived skeleton such as trimethylolpropane tri(meth)acrylate; (meth)acrylate compounds having a tetramethylolmethane-derived skeleton such as tetramethylolmethane tri(meth)acrylate and tetramethylolmethane tetra(meth)acrylate; and pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate. Examples include (meth)acrylate compounds having an erythritol-derived skeleton; (meth)acrylate compounds having a dipentaerythritol-derived skeleton such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate; (meth)acrylate compounds having a ditrimethylolpropane-derived skeleton such as ditrimethylolpropane tetra(meth)acrylate; (meth)acrylate compounds having a diglycerin-derived skeleton; and (meth)acrylates having a polyglycerin-derived skeleton. Among these, (meth)acrylate compounds having a dipentaerythritol-derived skeleton are preferred, and dipentaerythritol hexa(meth)acrylate is more preferred, from the viewpoint of improving chemical resistance after curing (exposure) and increasing the difference in developer resistance between the exposed and unexposed areas, and from the viewpoint of excellent insulation reliability (HAST resistance) and crack resistance. Component (Biii) may be used alone or two or more may be used in combination.

[0048] The content of component (B) in the photosensitive resin composition is not particularly limited, but may be 1 to 15% by mass, 2 to 12% by mass, or 3 to 9% by mass based on the total solid content of the photosensitive resin composition.

[0049] (Component (C): Photopolymerization Initiator) The photopolymerization initiator that is component (C) comprises a photopolymerization initiator having a fluorene skeleton.

[0050] Examples of the photopolymerization initiator having a fluorene skeleton include compounds represented by the following formula (1).

[0051]

[0052] In formula (1), R １ａ and R １ｂ each independently represent a hydrogen atom or a monovalent organic group. Examples of the monovalent organic group represented by R １ａ and R １ｂ include a halogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, a chain alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and an alkyl group having 1 to 10 carbon atoms substituted with a cycloalkyl group having 3 to 8 carbon atoms. R １ａ and R １ｂ may be the same or different. R １ａ and R １ｂ may be bonded to each other to form a cycloalkyl group having 3 to 8 carbon atoms. From the viewpoint of further excellent resolution, R １ａ and R １ｂ each independently may be a hydrogen atom, a linear alkyl group having 1 to 20 carbon atoms (for example, a linear alkyl group having 1 to 10 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, or a linear alkyl group having 1 to 4 carbon atoms), or a chain alkenyl group having 2 to 20 carbon atoms (for example, a chain alkenyl group having 2 to 10 carbon atoms or a chain alkenyl group having 2 to 4 carbon atoms), or may be bonded to each other to form a cycloalkyl group having 3 to 8 carbon atoms (for example, a cyclohexyl group).

[0053] R ２ａ and R ３ａ each independently represent a monovalent organic group. R ２ａ and R ３ａExamples of monovalent organic groups represented by include linear or branched alkyl groups having 1 to 20 carbon atoms, linear alkenyl groups having 2 to 20 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, alkyl groups having 1 to 10 carbon atoms substituted with cycloalkyl groups having 3 to 8 carbon atoms, or aryl groups having 6 to 20 carbon atoms. ２ａ and R ３ａ They may be the same or different. ２ａ and R ３ａ These may bond to form a cycloalkyl group having 3 to 8 carbon atoms. From the viewpoint of superior resolution, R ２ａ and R ３ａ Each of these may independently be a linear alkyl group having 1 to 20 carbon atoms (for example, a linear alkyl group having 1 to 10 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms, or a linear alkyl group having 1 to 3 carbon atoms).

[0054] R ４ａ This indicates a monovalent organic group containing a hydroxyl group or a nitrogen atom. Examples of monovalent organic groups containing a nitrogen atom include morpholinyl group, piperidinyl group, pyrrolidinyl group and -NR ９ａ R ９ｂ R is one example. ９ａ and R ９ｂ Each independently represents a linear or branched alkyl group having 1 to 5 carbon atoms (e.g., methyl group, ethyl group, propyl group, or butyl group). From the viewpoint of superior resolution, R ４ａ This may be a monovalent organic group containing a nitrogen atom.

[0055] X represents a hydrogen atom or a monovalent organic group. Examples of monovalent organic groups represented by X include linear or branched alkyl groups having 1 to 20 carbon atoms, linear alkenyl groups having 2 to 20 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, alkyl groups having 1 to 10 carbon atoms substituted with cycloalkyl groups having 3 to 8 carbon atoms, and -X １ - (X ２ ) ｎ X is one example. １ X represents a heteroatom selected from the group consisting of O, N, or S. ２X represents a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or an alkyl group having 1 to 10 carbon atoms substituted with a cycloalkyl group having 3 to 8 carbon atoms. ２ One or more of the carbon atoms in the compound may be substituted by the heteroatom described above, and n represents 1 or 2.

[0056] From the viewpoint of superior resolution, the photopolymerization initiator having a fluorene skeleton may be an α-aminoketone compound having a fluorene skeleton. Examples of α-aminoketone compounds having a fluorene skeleton include R ４ａ is a morpholinyl group, piperidinyl group, pyrrolidinyl group or -NR ９ａ R ９ｂ Examples of compounds represented by the above formula (1) are shown.

[0057] The upper limit of the molecular weight of the compound represented by formula (1) is not particularly limited, but may be 3000 or less, 2000 or less, 1000 or less, or 500 or less. The compound represented by formula (1) can be produced, for example, by the method described in Japanese Patent Publication No. 2019-528331. Examples of commercially available products of the compound represented by formula (1) include TR-NPI-20400 (manufactured by TRONLY, trade name).

[0058] Specific examples of photopolymerization initiators having a fluorene skeleton include 1-(9,9-dibutyl-9H-fluoren-2-yl)-2-methyl-2-morpholin-4-yl-propan-1-one.

[0059] Component (C) may consist solely of a photopolymerization initiator having a fluorene skeleton, or it may further contain a photopolymerization initiator other than a photopolymerization initiator having a fluorene skeleton (other photopolymerization initiators). Other photopolymerization initiators include, for example, acetophenone compounds such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane, and N,N-dimethylaminoacetophenone; anthraquinone compounds such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, and 2-aminoanthraquinone; benzophenone, methylbenzophenone, and 4,4'-dichloro Examples include benzophenone compounds such as benzophenone, 4,4'-bis(diethylamino)benzophenone, Michlaz ketone, and 4-benzoyl-4'-methyldiphenyl sulfide; acridine compounds such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; and oxime ester compounds such as 1,2-octanedione-1-[4-(phenylthio)phenyl]-2-(O-benzoyl oxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone-1-(O-acetyl oxime), and 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl) oxime].

[0060] The content of the photopolymerization initiator having a fluorene skeleton in component (C) may be 50 to 100% by mass, 60 to 100% by mass, or 70 to 100% by mass.

[0061] The content of component (C) in the photosensitive resin composition is not particularly limited, but may be 0.5 to 15% by mass, 1.0 to 10% by mass, or 1.5 to 5% by mass, based on the total solid content of the photosensitive resin composition.

[0062] (Component (D): Elastomer) The photosensitive resin composition according to this embodiment may contain an elastomer as component (D), but the content of the polybutadiene elastomer in the photosensitive resin composition is 0 to 2.0% by mass based on the total solid content of the photosensitive resin composition. That is, the photosensitive resin composition according to this embodiment includes embodiments that do not contain a polybutadiene elastomer, and embodiments that contain a polybutadiene elastomer in an amount greater than 0% by mass and less than or equal to 2.0% by mass based on the total solid content of the photosensitive resin composition.

[0063] Examples of polybutadiene-based elastomers include polymers of butadiene such as polybutadiene, epoxidized polybutadiene, and hydroxyl group-containing polybutadiene. Furthermore, the term "polybutadiene-based elastomer" as used herein also includes copolymers of butadiene with other polymerizable monomers (such as carboxylic acid-modified butadiene-acrylonitrile copolymers).

[0064] The number-average molecular weight (Mn) of the polybutadiene elastomer may be 1,000 to 50,000 or 3,000 to 20,000. In this specification, the number-average molecular weight (Mn) is the value obtained on a standard polystyrene basis by gel permeation chromatography (GPC) using tetrahydrofuran as the solvent.

[0065] As described above, the polybutadiene elastomer content is 0 to 2.0% by mass, based on the total solid content of the photosensitive resin composition. From the viewpoint of excellent crack resistance, it may be 0 to 1.4% by mass, 0 to 1.3% by mass, or 0 to 1.2% by mass, based on the total solid content of the photosensitive resin composition.

[0066] The photosensitive resin composition according to this embodiment may contain a polyester elastomer as component (D). That is, the photosensitive resin composition according to this embodiment includes embodiments that do not contain a polyester elastomer and embodiments that contain a polyester elastomer.

[0067] As the polyester elastomer, a compound obtained by polycondensation of a dicarboxylic acid or its derivative with a diol compound or its derivative can be used.

[0068] Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

[0069] Examples of diol compounds include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanediol; and aromatic diols such as bisphenol A, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)propane, and resorcinol.

[0070] As the polyester elastomer, a multiblock copolymer may be used in which aromatic polyester (e.g., polybutylene terephthalate) is used as the hard segment component and aliphatic polyester (e.g., polytetramethylene glycol) is used as the soft segment component. There are various grades of polyester elastomers depending on the type, ratio, and molecular weight of the hard and soft segments. Examples of commercially available multiblock copolymers include "Hytrel®" (manufactured by Toray DuPont Co., Ltd.), "Perprene®" (manufactured by Toyobo Co., Ltd.), "Esper®" and "Teslac®" (manufactured by Resonaq Co., Ltd.).

[0071] The number-average molecular weight (Mn) of the polyester elastomer may be 900 to 30,000, 1,000 to 25,000, or 5,000 to 20,000.

[0072] The polyester elastomer content may be 0 to 2.0% by mass based on the total solid content of the photosensitive resin composition, and may be 0 to 1.4% by mass, 0 to 1.0% by mass, or 0 to 0.7% by mass from the viewpoint of excellent insulation reliability (HAST resistance).

[0073] Other components (D) besides polybutadiene-based elastomers and polyester-based elastomers include, for example, olefin-based elastomers other than butadiene, styrene-based elastomers, urethane-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. These elastomers are composed of hard segment components that contribute to heat resistance and strength, and soft segment components that contribute to flexibility and toughness. Component (D) may be used alone or in combination of two or more types.

[0074] Examples of olefin-based elastomers other than butadiene include polymers or copolymers of α-olefins having 2, 3, and 5-20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methylpentene; and copolymers of α-olefins having 2, 3, and 5-20 carbon atoms with non-conjugated dienes having 2, 3, and 5-20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene. Specifically, examples include polyethylene, hydroxyl group-containing polyisopropylene, ethylene-propylene copolymer (EPR), and ethylene-propylene-diene copolymer (EPDM).

[0075] From the viewpoint of the adhesion of the cured product, as well as compatibility and solubility with other components contained in the photosensitive resin composition, component (D) is preferably an elastomer that is liquid at room temperature.

[0076] If the photosensitive resin composition according to this embodiment contains component (D), the content of component (D) (or the sum of the content of two or more elastomers if they are included) may be 0.1 to 3.5% by mass, 0.1 to 3.0% by mass, 0.1 to 2.5% by mass, or 0.1 to 2.0% by mass, based on the total solid content of the photosensitive resin composition (except when the content of polybutadiene elastomer exceeds 2.0% by mass, based on the total solid content of the photosensitive resin composition). When the content of component (D) is within the above range, resolution tends to be superior, and the adhesion and insulation reliability (HAST resistance) of the cured product tend to improve.

[0077] (Component (E): Thermosetting resin) The photosensitive resin composition according to this embodiment may also contain a thermosetting resin as component (E). By using component (E), the heat resistance, adhesion, and chemical resistance of the insulating layer formed from the photosensitive resin composition can be improved. Component (E) may be used alone or in combination of two or more types.

[0078] Examples of component (E) include epoxy resins, phenolic resins, unsaturated imide resins, cyanate resins, isocyanate resins, benzoxazine resins, oxetane resins, amino resins, unsaturated polyester resins, allyl resins, dicyclopentadiene resins, silicone resins, triazine resins, and melamine resins.

[0079] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, hydantoin type epoxy resin, triglycidyl isocyanurate, and bixylenol type epoxy resin.

[0080] The photosensitive resin composition according to this embodiment may further contain at least one thermosetting resin selected from the group consisting of bisphenol F type epoxy resins and phenol novolac type epoxy resins, from the viewpoint of excellent crack resistance.

[0081] The content of component (E) may be 5 to 30% by mass, 8 to 25% by mass, or 12 to 20% by mass, based on the total solid content of the photosensitive resin composition. When the content of component (E) is within the above range, the heat resistance of the formed insulating layer can be further improved while maintaining good developability.

[0082] (Component (F): Inorganic filler) The photosensitive resin composition according to this embodiment may further contain an inorganic filler as component (F). By including component (F), the adhesion and hardness of the insulating layer can be improved. Component (F) may be used alone or in combination of two or more types.

[0083] Examples of inorganic filler materials include silica, alumina, titania, tantalum oxide, zirconia, silicon nitride, barium titanate, barium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, lead titanate, lead zirconate titanate, lead lanthanum zirconate titanate, gallium oxide, spinel, mullite, cordierite, talc, aluminum titanate, yttria-containing zirconia, barium silicate, boron nitride, calcium carbonate, barium sulfate, calcium sulfate, zinc oxide, magnesium titanate, hydrotalcite, mica, calcined kaolin, and carbon.

[0084] Component (F) may contain silica filler from the viewpoint of improving the heat resistance of the insulating layer, and may contain barium sulfate filler from the viewpoint of improving the heat resistance and adhesion of the insulating layer, or may contain both silica filler and barium sulfate filler. Furthermore, component (F) may contain inorganic oxide filler or silica filler from the viewpoint of further improving heat dissipation. From the viewpoint of improving the dispersibility of the inorganic filler, inorganic filler that has been surface-treated with alumina or an organosilane compound beforehand may be used.

[0085] The shape of component (F) is not particularly limited, but it may be spherical from the viewpoint of improving crack resistance.

[0086] The average particle size of component (F) may be 0.01 to 5.0 μm, 0.05 to 3.0 μm, 0.1 to 2.0 μm, or 0.15 to 1.0 μm, from the viewpoint of superior resolution.

[0087] The average particle size of component (F) is the average particle size of the inorganic filler dispersed in the photosensitive resin composition, and is the value obtained by measurement as follows: First, the photosensitive resin composition is diluted 1000 times with methyl ethyl ketone, and then the particles dispersed in the solvent are measured using a submicron particle analyzer (Beckman Coulter, Inc., product name "N5") in accordance with the international standard ISO 13321, with a refractive index of 1.38, and the particle diameter at 50% of the cumulative value (by volume) in the particle size distribution is taken as the average particle size.

[0088] The content of component (F) may be 5 to 80% by mass, 5 to 70% by mass, 6 to 60% by mass, or 10 to 50% by mass, based on the total solid content of the photosensitive resin composition. When the content of component (F) is within the above range, the low coefficient of thermal expansion, heat resistance, and film strength can be further improved.

[0089] (Component (G): Pigment) The photosensitive resin composition according to this embodiment may further contain a pigment as component (G) from the viewpoint of improving the identifiability or appearance of the manufacturing apparatus. As component (G), a coloring agent that produces a desired color when concealing wiring (conductor patterns) can be used. Component (G) may be used alone or in combination of two or more types.

[0090] (G) Examples of components include phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, carbon black, and naphthalene black.

[0091] (G) The content of component (G) may be 0.01 to 5.0% by mass, 0.1 to 3.0% by mass, or 0.5 to 2.0% by mass, based on the total amount of solids in the photosensitive resin composition, from the viewpoint of making the manufacturing equipment easier to identify and better concealing the wiring.

[0092] (Other components) The photosensitive resin composition according to this embodiment may further contain, if necessary, other components such as photosensitizers and various additives.

[0093] Examples of photosensitizers include thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; phosphine compounds such as triphenylphosphine; toluidine compounds such as N,N-dimethyltoluidine; anthracene compounds such as 9,10-dimethoxyanthracene, 2-ethyl-9,10-dimethoxyanthracene, and 2-ethyl-9,10-diethoxyanthracene; perylene compounds; coumarin compounds; pyrarisone compounds; oxazole compounds; benzoxazole compounds; thiazole compounds; triazole compounds; stilbene compounds; triazine compounds; thiophene compounds; naphthalimide compounds; and triarylamine compounds.

[0094] From the viewpoint of maintaining good via shape, the photosensitizer is preferably 2,4-dimethylthioxanthone or 2,4-diethylthioxanthone, and more preferably 2,4-diethylthioxanthone. Using 2,4-diethylthioxanthone tends to reduce scattered light to unexposed areas, and as a result, good via shape can be maintained.

[0095] Other additives include polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol; silicone-based, fluorine-based, and vinyl resin-based defoaming agents; silane coupling agents; and flame retardants such as phosphate compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters.

[0096] The content of other components may be 0.01 to 5% by mass, 0.05 to 3% by mass, 0.1 to 2% by mass, or 0.3 to 1.5% by mass, based on the total solid content of the photosensitive resin composition.

[0097] (Solvent) The photosensitive resin composition according to this embodiment contains a solvent to dissolve and disperse each component, thereby facilitating application to a substrate and forming a coating film of uniform thickness.

[0098] Examples of solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; and esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate. The solvent may be used individually or in combination of two or more.

[0099] The amount of solvent is not particularly limited, but the proportion of solvent in the photosensitive resin composition may be 10 to 50% by mass, 20 to 40% by mass, or 25 to 35% by mass.

[0100] The photosensitive resin composition according to this embodiment is superior in resolution, insulation reliability (HAST resistance), and crack resistance, and therefore contains an acid-modified ethylenically unsaturated bond-containing phenol derivative as component (A) and dipentaerythritol hexa(meth)acrylate as component (B), but does not necessarily contain component (D).

[0101] The photosensitive resin composition according to this embodiment can be prepared by uniformly mixing the above-mentioned components using a roll mill, bead mill, or the like.

[0102] In the photosensitive resin composition according to this embodiment, the chlorine content may be 250 ppm by mass or less, 230 ppm by mass or less, or 210 ppm by mass or less, from the viewpoint of excellent insulation reliability (HAST resistance). The lower limit of the chlorine content is not particularly limited and may be 0 ppm by mass or more, 0.1 ppm by mass or more, or 1 ppm by mass or more. As a result of diligent research, the inventors have found that if the chlorine content in the photosensitive resin composition is within the above range, copper migration can be suppressed in printed circuit boards made using the photosensitive resin composition, thereby improving insulation reliability (HAST resistance).

[0103] In this specification, "chlorine" in "chlorine content" refers to chlorine in the ionic state, chlorine in the nonionic state, chlorine in inorganic chlorides, and chlorine in organic chlorides, and "chlorine content" refers to the total amount of these chlorines. The method for measuring the chlorine content in a photosensitive resin composition is not particularly limited and can be measured by known methods, for example, by ion chromatography.

[0104] [Photosensitive Element] The photosensitive element according to this embodiment comprises a support film and a photosensitive layer containing the above-described photosensitive resin composition. Figure 1 is a schematic cross-sectional view showing the photosensitive element according to this embodiment. As shown in Figure 1, the photosensitive element 1 comprises a support film 10 and a photosensitive layer 20 formed on the support film 10. The photosensitive element 1 may further include a protective film 30 on the photosensitive layer 20.

[0105] The photosensitive element 1 can be manufactured by applying the photosensitive resin composition according to this embodiment onto the support film 10 using a known coating apparatus such as a comma coater, bar coater, kiss coater, roll coater, gravure coater, or die coater, and then drying the coating to form a photosensitive layer 20. The thickness of the photosensitive layer is not particularly limited, but from the viewpoint of thinning the printed circuit board, it may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm.

[0106] The coating film can be dried using a hot air dryer, a dryer using far-infrared or near-infrared rays, etc. The drying temperature may be 60 to 150°C, 70 to 120°C, or 80 to 100°C. The drying time may be 1 to 60 minutes, 2 to 30 minutes, or 5 to 20 minutes. The residual solvent content in the coating film (photosensitive layer 20) after drying may be 3% by mass or less, 2% by mass or less, or 1% by mass or less, from the viewpoint of avoiding the diffusion of solvent in the manufacturing process of printed circuit boards. The solid content of each component other than volatile substances in the photosensitive layer 20 is the same as the solid content of each component in the photosensitive resin composition that forms the photosensitive layer 20.

[0107] Examples of support films include polyester films such as polyethylene terephthalate film and polybutylene terephthalate film; and polyolefin films such as polypropylene film and polyethylene film. The thickness of the support film may be, for example, 5 to 100 μm, 5 to 60 μm, or 15 to 45 μm.

[0108] For example, a polymer film such as polyethylene or polypropylene may be used as the protective film 30. The protective film 30 may be the same film as the support film 10, or a different film may be used.

[0109] The photosensitive resin composition according to this embodiment is suitable as a permanent resist for semiconductor elements and electronic devices, such as a surface protective layer for solder resist on printed circuit boards, and an insulating layer for interlayer insulation. Furthermore, the photosensitive resin composition according to this embodiment is also useful for forming cavities for embedding chips or passive elements.

[0110] [Printed wiring board and method for manufacturing a printed wiring board] The printed wiring board according to this embodiment comprises an insulating layer containing a cured product of the photosensitive resin composition according to this embodiment.

[0111] The method for manufacturing a printed circuit board according to this embodiment comprises the steps of: forming a photosensitive layer on a substrate using the photosensitive resin composition according to this embodiment; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form an insulating layer.

[0112] Figure 2 is a schematic cross-sectional view showing an example of a method for manufacturing a multilayer printed circuit board having a cured photosensitive resin composition as an insulating layer according to this embodiment. The multilayer printed circuit board 100A shown in Figure 2(f) has wiring patterns on its surface and inside. The multilayer printed circuit board 100A can be obtained by laminating a copper-clad laminate, an insulating layer, metal foil, etc., and forming wiring patterns as appropriate by etching or a semi-additive method. The method for manufacturing the multilayer printed circuit board 100A will be briefly described below based on Figure 2.

[0113] First, an interlayer insulating layer 103 is formed on both sides of a substrate (e.g., a copper-clad laminate) 101 having a wiring pattern 102 on its surface (see Figure 2(a)). The interlayer insulating layer 103 may be formed by printing the photosensitive resin composition according to this embodiment using a screen printing machine or a roll coater, or it may be formed by preparing a photosensitive element according to this embodiment in advance and attaching the photosensitive layer of the photosensitive element to the surface of the substrate 101 using a laminator.

[0114] Next, vias (openings) 104 are formed at locations where electrical connection to the outside is required by exposure and development, followed by heat curing (see Figure 2(b)).

[0115] Next, a seed layer 105 is formed by electroless plating (see Figure 2(c)). A photosensitive layer is formed on the seed layer 105 using a photosensitive dry film, and a resin pattern 106 is formed by exposing and developing predetermined areas (see Figure 2(d)).

[0116] Next, a wiring pattern 107 is formed in the areas of the seed layer 105 where the resin pattern 106 is not formed, using an electroplating method. After removing the resin pattern 106 with a stripping solution, the areas of the seed layer 105 where the wiring pattern 107 is not formed are removed by etching (see Figure 2(e)).

[0117] By repeating the above operations, a multilayer printed circuit board 100A can be manufactured by forming a surface protective layer 108 containing a cured product of the photosensitive resin composition according to this embodiment on the outermost surface (see Figure 2(f)). The multilayer printed circuit board 100A obtained in this way can, for example, have semiconductor elements mounted at corresponding locations to ensure electrical connections.

[0118] The permanent resist according to this embodiment can be used as an interlayer insulating layer or surface protective layer of a semiconductor element. A semiconductor element having an interlayer insulating layer or surface protective layer formed from the cured product of the above-described photosensitive resin composition, and an electronic device including the semiconductor element, can be manufactured. The semiconductor element may be, for example, a memory, package, etc., having a multilayer wiring structure, a rewiring structure, etc. Examples of electronic devices include mobile phones, smartphones, tablet terminals, personal computers, and hard disk suspensions. By providing a patterned cured product formed from the photosensitive resin composition according to this embodiment, highly reliable semiconductor elements and electronic devices can be provided.

[0119] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0120] (Synthesis Example 1) In an autoclave equipped with a thermometer, a nitrogen introduction device / alkylene oxide introduction device, and a stirring device, 119.4 parts by mass of novolac-type cresol resin (manufactured by Aica Kogyo Co., Ltd., trade name "Shounol CRG951", OH equivalent: 119.4 g / eq.), 1.19 parts by mass of potassium hydroxide, and 119.4 parts by mass of toluene were charged, and the system was heated and the temperature increased while stirring and purging with nitrogen. Next, 63.8 parts by mass of propylene oxide was gradually introduced into the reactor, and the temperature was raised to 125-132°C and 0-4.8 kg / cm³. ２The reaction was carried out for 16 hours. After cooling to room temperature, 1.56 parts by mass of 89% phosphoric acid was added to the reaction solution and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac-type cresol resin with a non-volatile content of 62.1% by mass and a hydroxyl value of 182.2 mg KOH / g. This solution contained an average of 1.08 moles of propylene oxide per equivalent of phenolic hydroxyl groups.

[0121] Next, 293.0 parts by mass of the obtained novolac-type cresol resin propylene oxide reaction solution, 43.2 parts by mass of acrylic acid, 11.53 parts by mass of methanesulfonic acid, 0.18 parts by mass of methylhydroquinone, and 252.9 parts by mass of toluene were charged into a reactor equipped with a stirrer, thermometer, and air blowing tube, and the reaction was carried out at 110°C for 12 hours while stirring and blowing air at a rate of 10 ml / min. Of the water produced by the reaction, 12.6 parts by mass of water was distilled off as an azeotropic mixture with toluene. After that, the solution was cooled to room temperature, neutralized with 35.35 parts by mass of a 15% by mass sodium hydroxide aqueous solution, and then washed with water. Subsequently, toluene was removed by distillation in an evaporator while substituting with 118.1 parts by mass of diethylene glycol monoethyl ether acetate (carbitol acetate) to obtain a novolac-type acrylate resin solution.

[0122] Next, 332.5 parts by mass of the obtained novolac-type acrylate resin solution and 1.22 parts by mass of triphenylphosphine were charged into a reactor equipped with a stirrer, thermometer, and air blowing tube. While stirring and blowing air at a rate of 10 ml / min, 60.8 parts by mass of tetrahydrophthalic anhydride (THPAC) were gradually added, and the reaction was carried out at 95-101°C for 6 hours. By cooling the reaction solution, a solution of resin (A-1) (acid-modified ethylenically unsaturated bond-containing phenol derivative) having ethylenically unsaturated bonds and acidic groups as component (A) was obtained, with a solid acid value of 88 mg KOH / g and a solid content concentration of 70.9% by mass.

[0123] (Synthesis Example 2) Bisphenol F novolac type epoxy resin (manufactured by DIC Corporation, trade name "EXA-7376", in formula (II), Y ３ and Y ４ is a glycidyl group, R１２ 350 parts by mass of bisphenol F novolac-type epoxy resin having a structural unit in which hydrogen atoms (epoxy equivalent: 186), 70 parts by mass of acrylic acid, 0.5 parts by mass of methyl hydroquinone, and 120 parts by mass of carbitol acetate were charged and heated to 90°C and stirred to dissolve the mixture. Next, the obtained solution was cooled to 60°C, 2 parts by mass of triphenylphosphine were added, and the mixture was heated to 100°C and reacted until the acid value of the solution was 1 mg KOH / g or less. To the reacted solution, 98 parts by mass of tetrahydrophthalic anhydride (THPAC) and 85 parts by mass of carbitol acetate were added, and the mixture was heated to 80°C and reacted for 6 hours. After that, the solution was cooled to room temperature to obtain a solution of resin (A-2) (acid-modified ethylenically unsaturated bond-containing epoxy derivative) having ethylenically unsaturated bonds and acidic groups as component (A), with a solid content concentration of 73% by mass.

[0124] The following materials were prepared as components (B) to (F): B-1: Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., trade name "DPHA") B-2: Acrylate with a polyglycerin-derived skeleton (manufactured by Sakamoto Pharmaceutical Co., Ltd., trade name "SA-TE6") C-1: 1-(9,9-dibutyl-9H-fluoren-2-yl)-2-methyl-2-morpholin-4-ylpropan-1-one (photopolymerization initiator with a fluorene skeleton, manufactured by TRONLY Co., Ltd., trade name "TR-NPI-20400") C-2: 2-methyl-[4-(methylthio)phenyl]morpholino-1-propanone (manufactured by IGM Resins B.V., trade name "Omnirad 907") C-3: 2,4-diethylthioxanthone D-1: Polybutadiene elastomer (manufactured by Daicel Corporation, product name "Epolide PB3600") D-2: Polyester elastomer (manufactured by Resonac Corporation, product name "SP1108") E-1: Phenol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name "RE-306") E-2: Bisphenol F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YL983U") F-1: Spherical silica filler (manufactured by Admatex, product name "Admafine", average particle size: 0.5 μm) G-1: Pigment (mixture of blue pigment and yellow pigment)

[0125] (Examples 1-7 and Comparative Examples 1-4) [Preparation of Photosensitive Resin Compositions] Each component was blended in the amounts (parts by mass, equivalent to solid content) shown in Table 1 or Table 2 and kneaded in a three-roll mill. Then, methyl ethyl ketone was added to prepare a photosensitive resin composition so that the solid content concentration was 65% by mass.

[0126] [Preparation of Photosensitive Element] A polyethylene terephthalate film with a thickness of 25 μm (manufactured by Toyobo Co., Ltd., product name: HPES0) was prepared as a support film. The photosensitive resin composition was applied to the support film so that its thickness after drying was 18 μm, and dried at 100°C for 10 minutes using a hot air convection dryer to form a photosensitive layer. Next, a polyethylene film (manufactured by Tamapoly Co., Ltd., product name: NF-13) was laminated as a protective film onto the surface opposite to the side of the photosensitive layer that is in contact with the support film to obtain a photosensitive element.

[0127] [Resolution Evaluation] (1) Preparation of evaluation laminate A printed circuit board substrate (manufactured by Resonac Co., Ltd., product name "MCL-E-679") made by laminating 12 μm thick copper foil onto a glass epoxy substrate was treated with a roughening solution (manufactured by MEC Co., Ltd., product name "CZ-8100") on the copper foil surface, then washed with water and dried to obtain a roughened printed circuit board substrate.

[0128] Next, the protective film was peeled off from the photosensitive elements manufactured in each example and comparative example. The exposed photosensitive layer was then placed in contact with the copper foil of the roughened printed circuit board substrate, and laminated using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500"). The lamination conditions were: atmospheric pressure of 4 kPa or less, vacuuming time of 20 seconds, pressing pressure of 0.4 MPa, press hot plate temperature of 75°C, and lamination press time of 30 seconds. After lamination, the laminate was left at room temperature for more than one hour to obtain an evaluation laminate in which the photosensitive layer and support film were laminated in that order on the copper foil surface of the printed circuit board substrate.

[0129] (2) Sensitivity measurement of the photosensitive layer A 41-step tablet was placed on the support film of the evaluation laminate obtained in (1) above, and exposure was performed using an i-line exposure apparatus (manufactured by Ushio Inc., model number "UX-2240SM"). After exposure, the material was left at room temperature for 30 minutes, and then the unexposed areas of the photosensitive resin composition were spray-developed for 40 seconds using a 1% by mass aqueous sodium carbonate solution at 30°C. Exposure energy was 50 to 1000 mJ / cm². ２ Within the range of 50 mJ / cm ２ Perform the above operation while gradually changing the exposure energy, and after development, find the exposure energy amount at which the glossy remaining step number of the 41-step tablet becomes 10.0, which corresponds to the sensitivity of the photosensitive layer (unit: mJ / cm²). ２ )

[0130] (3) Preparation of test specimens The support film of the evaluation laminate obtained in (1) above was exposed using an i-line exposure apparatus (manufactured by Ushio Inc., product name "UX-2240SM"). The exposure pattern used was a grid pattern of dots (dot diameter:distance between dot centers = 1:2). The dot diameter (Φ) was varied in 5 μm increments within the range of 20 to 100 μm. Exposure was performed at an exposure energy amount that resulted in a sensitivity of the photosensitive layer, i.e., a remaining step stage of 10.0, as measured in (2) above. After exposure, the specimen was left at room temperature for 40 minutes, and then the unexposed photosensitive resin composition was spray-developed for 40 seconds using a 1% by mass aqueous solution of sodium carbonate at 30°C. Next, the developed photosensitive layer was exposed to 2000 mJ / cm using an ultraviolet exposure apparatus. ２ The specimens were then post-exposed with the specified exposure dose. Subsequently, they were post-heated at 170°C for 1 hour using a hot air circulation dryer. Through these operations, test specimens were obtained having a cured film on a copper-clad laminate with a via pattern of a predetermined size.

[0131] (4) Evaluation The via patterns of the specimens obtained in (3) above were observed using a scanning electron microscope. The diameter of the base of the vias with a mask diameter of Φ25 μm was measured, and the resolution was evaluated according to the following evaluation criteria. The results are shown in Tables 1 and 2. <Evaluation Criteria> A: The diameter of the base of the via is greater than 14 μm B: The diameter of the base of the via is 12 μm or more and 14 μm or less C: The diameter of the base of the via is less than 12 μm

[0132]

[0133]

[0134] The following evaluation tests were also performed on the photosensitive resin compositions of Examples 1 to 7.

[0135] [Analysis of Chlorine Content] The chlorine content of the photosensitive layer of the fabricated photosensitive element was measured by combustion tube decomposition-ion chromatography using the following procedure. First, the photosensitive layer was removed from the photosensitive element, and an arbitrary weight (approximately 10 mg) was weighed to be used as the analytical sample. The analytical sample was humidified and combusted, and the resulting gas was absorbed into an absorption solution. The chlorine content (mass ppm) in the absorption solution was quantified by ion chromatography and evaluated according to the following evaluation criteria. The results are shown in Table 3. <Evaluation Criteria> A: Chlorine content is 250 mass ppm or less B: Chlorine content exceeds 250 mass ppm

[0136] [Insulation Reliability (HAST Resistance) Evaluation] Test specimens were prepared in the same manner as in the [Resolution Evaluation] above, except that an evaluation substrate with comb-shaped electrodes (line / space = 10 μm / 10 μm) was used instead of a copper-clad laminate substrate, and the entire surface was exposed without using a negative mask. The test specimens were then exposed to 130°C, 85% RH, and 3.5 V. The resistance between the electrodes was measured, and if the resistance value was 10 －６ The time at which the resistance fell below Ω was defined as the copper migration occurrence time. Based on the copper migration occurrence time, insulation reliability (HAST resistance) was evaluated according to the following evaluation criteria. The results are shown in Table 3. <Evaluation Criteria> A: 300 hours or more B: 200 hours or more but less than 300 hours C: 150 hours or more but less than 200 hours D: Less than 150 hours

[0137] [Evaluation of crack resistance] (1) Preparation of evaluation laminate A photosensitive layer and a support film were laminated in this order on the copper foil surface of a printed circuit board substrate in the same manner as in [Evaluation of resolution] above.

[0138] (2) Preparation of test specimens The support film of the evaluation laminate obtained in (1) above was exposed using an i-line exposure apparatus (manufactured by Ushio Inc., product name "UX-2240SM"). The exposure pattern used was a grid pattern of square dots (dot diameter:distance between dot centers = 1:2). The diameter (Φ) of the square dots was varied in 5 μm increments within the range of 20 to 100 μm. Exposure was performed at an exposure energy amount that resulted in a sensitivity of the photosensitive layer, i.e., a remaining step stage of 10.0, as measured in [Resolution Evaluation] above. After exposure, the specimens were left at room temperature for 40 minutes, and then the unexposed areas of the photosensitive resin composition were spray-developed for 40 seconds using a 1% by mass aqueous solution of sodium carbonate at 30°C. Next, the developed photosensitive layer was exposed to 2000 mJ / cm using an ultraviolet exposure apparatus. ２ Post-exposure was performed with the specified exposure dose. Subsequently, post-heating was carried out at 170°C for 1 hour using a hot air circulation dryer. Through these operations, a test specimen was obtained having a cured film on a copper-clad laminate with a predetermined size square via pattern formed thereon.

[0139] (3) Thermal cycling test A thermal cycling test was performed using the test specimens obtained in (2) above. After being exposed to air at -65°C for 15 minutes, the temperature was raised to 150°C at a heating rate of 180°C / min, then exposed to air at 150°C for 15 minutes, and then cooled down to -65°C at a cooling rate of 180°C / min. This thermal cycle was repeated 1000 times.

[0140] (4) Evaluation After the thermal cycling test, the hardened film of the specimen was observed using a metallurgical microscope at 100x magnification. For each region with square vias of aperture sizes of 60 μm and 70 μm, 10 arbitrary locations were observed, each being 2 mm square. The presence or absence of cracks and the condition of the cracks were observed, and crack resistance was evaluated according to the following criteria. The results are shown in Table 3. <Evaluation Criteria> A: No cracks connecting the square vias occurred. B: Cracks connecting the square vias occurred in 1, 2, or 3 out of 10 locations. C: Cracks connecting the square vias occurred in 4 or more out of 10 locations.

[0141]

[0142] 1...Photosensitive element, 10...Support film, 20...Photosensitive layer, 30...Protective film, 100A...Multilayer printed circuit board, 101...Substrate, 102, 107...Wiring pattern, 103...Interlayer insulating layer, 104...Via, 105...Seed layer, 106...Resin pattern, 108...Surface protective layer.

Claims

1. A photosensitive resin composition comprising a resin having ethylenically unsaturated bonds and acidic groups, a photopolymerizable compound, and a photopolymerization initiator having a fluorene skeleton, wherein the polybutadiene elastomer content is 0 to 2.0% by mass, based on the total solid content of the photosensitive resin composition.

2. The photosensitive resin composition according to claim 1, wherein the content of the polyester elastomer is 0 to 1.4% by mass, based on the total amount of solids in the photosensitive resin composition.

3. The photosensitive resin composition according to claim 1, further comprising at least one thermosetting resin selected from the group consisting of bisphenol F type epoxy resins and phenol novolac type epoxy resins.

4. The photosensitive resin composition according to claim 1, wherein the photopolymerizable compound comprises dipentaerythritol hexa(meth)acrylate.

5. The photosensitive resin composition according to claim 1, wherein the chlorine content is 250 ppm by mass or less.

6. A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the photosensitive layer contains the photosensitive resin composition described in any one of claims 1 to 5.

7. A printed circuit board comprising an insulating layer containing a cured product of the photosensitive resin composition according to any one of claims 1 to 5.

8. A method for manufacturing a printed circuit board, comprising the steps of: forming a photosensitive layer on a substrate using a photosensitive resin composition according to any one of claims 1 to 5; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form an insulating layer.

9. A method for manufacturing a printed circuit board, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element described in claim 6; exposing and developing the photosensitive layer to form a resist pattern; and curing the resist pattern to form an insulating layer.

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