Photosensitive element, method for forming resist pattern, and method for producing printed circuit board

Abstract

The photosensitive element according to the present disclosure comprises a substrate and a photosensitive layer formed on this substrate. The photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer. The thickness of the photosensitive layer is less than 10 μm. The photosensitive layer has a light transmittance of over 70% at a wavelength of 405 nm.

Description

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

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

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

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

[0004] JP 2009-003177 A JP 2013-195712 A

[0005] In recent years, as printed wiring boards have become increasingly dense and conductor patterns have become increasingly finer, there has been a demand for photosensitive elements capable of forming fine resist patterns with line and space widths of 2 μm or less, and therefore the photosensitive layer is required to have excellent resolution in forming the resist pattern.

[0006] An object of the present disclosure is to provide a photosensitive element with excellent resolution, a method for forming a resist pattern, and a method for producing a printed wiring board.

[0007] One aspect of the present disclosure relates to the following photosensitive element, method for forming a resist pattern, and method for manufacturing a printed wiring board. [1] A photosensitive element comprising a support and a photosensitive layer formed on the support, the photosensitive layer containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, the photosensitive layer having a thickness of less than 10 μm and a light transmittance of more than 70% at a wavelength of 405 nm. [2] The photosensitive element according to [1] above, wherein the sensitizer contains an anthracene compound and a pyrazoline compound. [3] The photosensitive element according to [1] above, wherein the sensitizer contains an anthracene compound, and the content of the anthracene compound is 0.70 parts by mass or more per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound. [4] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element described in any one of [1] to [3] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern. [5] A method for producing a printed wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern described in [4] above to form a conductor pattern.

[0008] According to the present disclosure, it is possible to provide a photosensitive element having excellent resolution, a method for forming a resist pattern, and a method for manufacturing a printed wiring board. The photosensitive element of the present disclosure includes a photosensitive layer having excellent resolution, and therefore can form a fine resist pattern with a resolution of 2 μm or less.

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

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In this specification, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. The term "layer" encompasses not only a structure that is formed over the entire surface when observed in a plan view, but also a structure that is formed on a portion of the surface. Numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a numerical range of a certain stage may be replaced with the upper or lower limit of a numerical range of another stage. In numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples.

[0011] In this specification, "(meth)acrylate" means at least one of "acrylate" and its corresponding "methacrylate." The same applies to other similar expressions such as "(meth)acryloyl."

[0012] In this specification, the amount of each component in a photosensitive resin composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified. In this specification, the term "solid content" refers to the non-volatile content of the photosensitive resin composition excluding volatile substances (water, solvent, etc.). In other words, the term "solid content" refers to components other than the solvent that remain without volatilizing upon drying of the photosensitive resin composition, as described below, and includes components that are liquid, syrup-like, or waxy at room temperature (25°C).

[0013] [Photosensitive Element] The photosensitive element according to this embodiment includes a support and a photosensitive layer formed on the support. The photosensitive layer contains (A) a binder polymer (hereinafter also referred to as "component (A)"), (B) a photopolymerizable compound (hereinafter also referred to as "component (B)"), (C) a photopolymerization initiator (hereinafter also referred to as "(C)"), and (D) a sensitizer (hereinafter also referred to as "component (D)"). The photosensitive layer has a thickness of less than 10 μm, and a light transmittance of more than 70% at a wavelength of 405 nm. The photosensitive element according to this embodiment includes a photosensitive layer having such a specific thickness and specific light transmittance, thereby enabling the formation of a resist pattern with excellent resolution.

[0014] Fig. 1 is a schematic cross-sectional view of a photosensitive element according to one embodiment. As shown in Fig. 1, the photosensitive element 1 includes a support 2 and a photosensitive layer 3 formed on the support 2, and may also include other layers such as a protective layer 4, which may be provided as needed.

[0015] (Photosensitive Layer) The photosensitive layer is a layer formed using a photosensitive resin composition containing (A) a binder polymer, (B) a photopolymerizable compound, (C) a photopolymerization initiator, and (D) a sensitizer. The photosensitive resin composition may further contain a polymerization inhibitor or other components as needed. The solid content of each component contained in the photosensitive layer other than the volatile substance may be within the numerical range of the solid content of each component contained in the photosensitive resin composition described above. Each component will be described below.

[0016] Component (A): Binder Polymer The photosensitive resin composition contains one or more components (A), such as acrylic resins, styrene resins, epoxy resins, amide resins, amide-epoxy resins, alkyd resins, and phenolic resins.

[0017] From the viewpoint of alkali developability, the component (A) may contain an acrylic resin. The acrylic resin is a resin having structural units (monomer units) derived from a (meth)acryloyl group-containing compound.

[0018] The (meth)acryloyl group-containing compound is a compound containing a (meth)acryloyl group. Examples of the (meth)acryloyl group-containing compound include hydroxyalkyl (meth)acrylate, (meth)acrylic acid, (meth)acrylic acid alkyl ester, (meth)acrylic acid aryl ester, (meth)acrylic acid cycloalkyl ester, acrylamide such as diacetone acrylamide, (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid dimethylaminoethyl ester, (meth)acrylic acid diethylaminoethyl ester, (meth)acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, α-bromoacrylic acid, α-chloroacrylic acid, β-furyl (meth)acrylic acid, and β-styryl (meth)acrylic acid.

[0019] The acrylic resin may be, for example, a polymer (a) having at least one unit selected from the group consisting of a hydroxyalkyl (meth)acrylate unit, a (meth)acrylic acid unit, a (meth)acrylic acid cycloalkyl ester unit, a (meth)acrylic acid alkyl ester unit, and a (meth)acrylic acid aryl ester unit.

[0020] The hydroxyalkyl (meth)acrylate unit is a structural unit derived from a hydroxyalkyl (meth)acrylate. Examples of the hydroxyalkyl (meth)acrylate include hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, and hydroxyhexyl (meth)acrylate. When the alkyl moiety in the hydroxyalkyl (meth)acrylate unit has 3 or more carbon atoms, the hydroxyalkyl (meth)acrylate unit may have a branched structure.

[0021] When the polymer (a) has a hydroxyalkyl (meth)acrylate unit, the content of the hydroxyalkyl (meth)acrylate unit may be 0.5% by mass or more, 0.75% by mass or more, or 1.0% by mass or more, based on the total amount of monomer units constituting the polymer (a), from the viewpoint of dispersibility, and may be 20% by mass or less, 15% by mass or less, or 8% by mass or less, from the viewpoint of water absorbency.

[0022] The (meth)acrylic acid unit is a structural unit derived from (meth)acrylic acid. When the polymer (a) has a (meth)acrylic acid unit, the content of the (meth)acrylic acid unit may be 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, based on the total amount of monomer units constituting the polymer (a), from the viewpoints of resolution and adhesion, and may be 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less. From the viewpoints of developability and strippability, the (meth)acrylic acid unit may be an acrylic acid unit.

[0023] The (meth)acrylic acid cycloalkyl ester unit is a structural unit derived from a (meth)acrylic acid cycloalkyl ester. Examples of the (meth)acrylic acid cycloalkyl ester include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclopentanyl (meth)acrylate, and dicyclopentanyl (meth)acrylate. The content of the (meth)acrylic acid cycloalkyl ester unit may be 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, or 6% by mass or more, and may be 15% by mass or less, 10% by mass or less, or 8% by mass or less, based on the total amount of all the monomers constituting the polymer (a).

[0024] The (meth)acrylic acid alkyl ester unit is a structural unit derived from a (meth)acrylic acid alkyl ester. The alkyl group of the (meth)acrylic acid alkyl ester may be, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, or a structural isomer thereof, or may be an alkyl group having 1 to 4 carbon atoms from the viewpoint of releasability.

[0025] When the polymer (a) has (meth)acrylic acid alkyl ester units, the content of the (meth)acrylic acid alkyl ester units may be 1 mass % or more, 2 mass % or more, 3 mass % or more, or 4 mass % or more, based on the total amount of monomer units constituting the polymer (a), from the viewpoint of releasability, and may be 50 mass % or less, 30 mass % or less, 10 mass % or less, 8 mass % or less, or 6 mass % or less, from the viewpoint of resolution and adhesion.

[0026] The (meth)acrylic acid aryl ester unit is a structural unit derived from a (meth)acrylic acid aryl ester. Examples of the (meth)acrylic acid aryl ester include benzyl (meth)acrylate, phenyl (meth)acrylate, and naphthyl (meth)acrylate. When the polymer (a) has a (meth)acrylic acid aryl ester unit, the content of the (meth)acrylic acid aryl ester unit may be 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, or 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, 30% by mass or less, or 25% by mass or less, based on the total amount of the monomer units constituting the polymer (a), from the viewpoint of resolution and adhesion.

[0027] The polymer (a) may further have a structural unit derived from a monomer other than the (meth)acryloyl group-containing compound. The other monomer may be one type or two or more types.

[0028] Examples of other monomers include styrene or styrene derivatives, acrylonitrile, vinyl alcohol ethers such as vinyl n-butyl ether, maleic acid, maleic anhydride, maleic acid monoesters such as monomethyl maleate, monoethyl maleate, and monoisopropyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. Examples of styrene derivatives include vinyltoluene and α-methylstyrene.

[0029] When the polymer (a) has a structural unit derived from styrene or a styrene derivative (hereinafter also referred to as a "styrene or styrene derivative unit"), the content of the styrene or styrene derivative unit, based on the total amount of the monomer units constituting the polymer (a), may be 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more from the viewpoint of resolution, and may be 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less from the viewpoint of developability.

[0030] The component (A) may contain a binder polymer other than the polymer (a), or may consist solely of the polymer (a). From the viewpoints of adhesion and resolution, the content of the polymer (a) in the component (A) may be 50 to 100 mass % or 80 to 100 mass % based on the total amount of the component (A).

[0031] The acid value of polymer (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 developability; and may be 250 mgKOH / g or less, 240 mgKOH / g or less, 230 mgKOH / g or less, 200 mgKOH / g or less, 180 mgKOH / g or less, or 160 mgKOH / g or less from the viewpoint of adhesion of the cured product of the photosensitive resin composition. The acid value of polymer (a) can be adjusted by the content of structural units (e.g., (meth)acrylic acid units) constituting polymer (a). When component (A) contains a binder polymer other than polymer (a), the acid value of the other binder polymer may also be within the above range. The acid value can be measured by the following procedure. First, 1 g of the binder polymer to be measured for acid value is precisely weighed, and then 30 g of acetone is added to the binder polymer to uniformly dissolve it, thereby obtaining a solution. Next, an appropriate amount of phenolphthalein as an indicator is added to the solution, and then titration is performed using a 0.1 N aqueous solution of potassium hydroxide (KOH). The acid value is determined by calculating the mass (unit: mg) of KOH required to neutralize the acetone solution of the binder polymer.

[0032] The weight average molecular weight (Mw) of the polymer (a) may be 10,000 or more, 15,000 or more, 20,000 or more, 25,000 or more, 30,000 or more, 35,000 or more, or 40,000 or more from the viewpoint of adhesion of the cured product of the photosensitive resin composition and formability of a resist pattern, and may be 100,000 or less, 80,000 or less, 60,000 or less, 50,000 or less, or 45,000 or less from the viewpoint of developability. The dispersity (Mw / Mn) of the polymer (a) may be, for example, 1.0 or more or 1.5 or more, and from the viewpoint of adhesion and resolution, may be 3.0 or less or 2.5 or less. When the component (A) contains a binder polymer other than the polymer (a), the Mw of the other binder polymer may also be within the above range.

[0033] The weight average molecular weight and dispersity can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. For compounds with low molecular weights, if it is difficult to measure the weight average molecular weight using the above-mentioned method, the molecular weight can be measured by another method and the average calculated. The GPC conditions are as follows: Pump: Hitachi L-6000 type (trade name, manufactured by Hitachi, Ltd.) Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (all manufactured by Resonac Corporation, trade names) Eluent: tetrahydrofuran Measurement temperature: 40°C Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (trade name, manufactured by Hitachi, Ltd.)

[0034] From the viewpoint of resolution or adhesion, the glass transition temperature (Tg) of the polymer (a) may be 70 to 125° C., 90 to 120° C., or 94 to 110° C. The Tg is a value determined according to the Fox equation, and can be calculated from the mass of each monomer constituting the polymer (a) and the Tg of a homopolymer of each of the monomers.

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

[0036] Component (B): Photopolymerizable Compound The photosensitive resin composition contains one or more components (B). The component (B) is not particularly limited as long as it has at least one ethylenically unsaturated bond and is a photopolymerizable compound.

[0037] From the viewpoints of alkali developability, resolution, and release properties after curing, the component (B) may contain at least one bisphenol (meth)acrylate. The bisphenol (meth)acrylate may be a bisphenol A (meth)acrylate. Examples of bisphenol A (meth)acrylates include 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolypropoxy)phenyl)propane, 2,2-bis(4-((meth)acryloxypolybutoxy)phenyl)propane, and 2,2-bis(4-((meth)acryloxypolyethoxypolypropoxy)phenyl)propane.

[0038] From the viewpoint of resolution and release properties, component (B) may contain 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane. As the 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane, a compound having 10 or more oxyethylene groups may be used, or a compound having less than 10 oxyethylene groups may be used, or a compound having 10 or more oxyethylene groups and a compound having less than 10 oxyethylene groups may be used in combination.

[0039] Examples of commercially available bisphenol A (meth)acrylates include 2,2-bis(4-((meth)acryloxydipropoxy)phenyl)propane, such as BPE-200 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.), ethoxylated bisphenol A dimethacrylate, such as BP-2EM (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), and 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane, such as BPE-500 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.), and FA-321M (trade name, manufactured by Resonac Corporation). These bisphenol A (meth)acrylates may be used alone or in combination of two or more.

[0040] The content of the bisphenol (meth)acrylate may be 40 to 98 mass%, 50 to 97 mass%, or 60 to 95 mass%, based on the total amount of component (B). A content of 40 mass% or more improves resolution, adhesion, and suppression of resist tail formation, while a content of 98 mass% or less shortens the development time appropriately and makes it more difficult for undeveloped residue to occur.

[0041] The component (B) other than the bisphenol-type (meth)acrylate may further include at least one polyalkylene glycol di(meth)acrylate having at least one of a (poly)oxyethylene chain and a (poly)oxypropylene chain in the molecule, from the viewpoint of improving the flexibility of the cured product (cured film), or may further include a polyalkylene glycol di(meth)acrylate having both a (poly)oxyethylene chain and a (poly)oxypropylene chain in the molecule. The total number of oxyethylene groups (EO groups) and / or oxypropylene groups (PO groups) in the polyalkylene glycol di(meth)acrylate may be 2 to 40, 4 to 30, or 6 to 20, from the viewpoint of further improving adhesion and resolution.

[0042] Examples of polyalkylene glycol di(meth)acrylates include FA-023M (trade name, manufactured by Resonac Corporation), FA-024M (trade name, manufactured by Resonac Corporation), and NK Ester HEMA-9P (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). These may be used alone or in combination of two or more.

[0043] The content of the polyalkylene glycol di(meth)acrylate may be 2 to 40 mass %, 3 to 30 mass %, or 5 to 20 mass %, based on the total amount of the component (B).

[0044] Other examples of component (B) that may be used include nonylphenoxy polyethyleneoxy acrylate, phthalic acid compounds, (meth)acrylic acid polyol esters, and (meth)acrylic acid alkyl esters.

[0045] The content of the component (B) may be 20 to 60 parts by mass, 30 to 55 parts by mass, or 35 to 50 parts by mass, relative to 100 parts by mass of the total amount of the components (A) and (B).

[0046] The photosensitive resin composition contains one or more components (C). The component (C) is not particularly limited as long as it is a component that can polymerize the component (B), and can be appropriately selected from commonly used photopolymerization initiators.

[0047] The component (C) may include a hexaarylbiimidazole compound. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. The hydrogen atom bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (e.g., a chlorine atom).

[0048] The hexaarylbiimidazole compound may be a 2,4,5-triarylimidazole dimer, such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-bis-(m-methoxyphenyl)imidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer.

[0049] The content of component (C) may be 1.0 to 10 parts by mass, 2.0 to 8 parts by mass, 3.0 to 7.0 parts by mass, or 4.0 to 6.0 parts by mass, relative to 100 parts by mass of the total amount of component (A) and component (B). When the content of component (C) is within this range, it becomes easy to improve both sensitivity and resolution in a balanced manner.

[0050] Component (D): Sensitizer The photosensitive resin composition contains one or more types of component (D). By using component (D), the photosensitive resin composition can effectively utilize the absorption wavelength of the actinic ray used for exposure.

[0051] Examples of component (D) include pyrazoline compounds, anthracene compounds, dialkylaminobenzophenone compounds, coumarin compounds, xanthone compounds, thioxanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, naphthalimide compounds, triarylamine compounds, and aminoacridine compounds. From the viewpoint of further improving resolution and sensitivity, component (D) may contain a pyrazoline compound or an anthracene compound.

[0052] The pyrazoline compound may be a phenyl group-containing pyrazoline compound. Examples of the phenyl group-containing pyrazoline compound include 1-(4-methoxyphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1,5-bis-(4-methoxyphenyl)-3-(4-methoxystyryl)-pyrazoline, 1-(4-isopropylphenyl)-3-styryl-5-phenyl-pyrazoline, 1-phenyl-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, and 1,5-bis-(4-isopropylphenyl)-3-styryl-5-phenyl-pyrazoline. 1-(4-tert-butyl-phenyl)-3-(4-isopropylstyryl)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4- 1-(4-isopropyl-styryl)-5-(4-isopropyl-phenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-isopropylstyryl)-5-(4-isopropylphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-methoxystyryl)-5-(4-methoxyphenyl)-pyrazoline, 1-phenyl-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline Pyrazoline, 1-phenyl-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-( 4-methoxyphenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,4-dimethoxystyryl)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-tert- butyl-phenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,5-dimethoxystyryl)-5-(3,5-dimethoxyphenyl)-pyrazoline 1-(4-isopropyl-phenyl)-3-(2,6-dimethoxystyryl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,5-dimethoxystyryl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,3-dimethoxystyryl)-5-(2,3-dimethoxyphenyl)-pyrazoline, and 1-(4-isopropyl-phenyl)-3-(2,4-dimethoxystyryl)-5-(2,4-dimethoxyphenyl)-pyrazoline.

[0053] Examples of the anthracene compound include 1-methylanthracene, 2-methylanthracene, 9-methylanthracene, 2-ethylanthracene, 2-butylanthracene, 9-vinylanthracene, 9-phenylanthracene, 1-aminoanthracene, 2-aminoanthracene, 9-(methylaminomethyl)anthracene, 9-acetylanthracene, 9-anthraldehyde, 9,10-dimethylanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-di(2-ethylhexyloxy)anthracene, 9,10-diphenylanthracene, 2-bromo-9,10-diphenylanthracene, 9-(4-bromophenyl)-10-phenylanthracene, 10-methyl-9-anthraldehyde, and 1,4,9,10-tetrahydroxyanthracene.

[0054] The anthracene compound may be a compound having an alkoxy group bonded to the anthracene ring (for example, a dialkoxyanthracene compound having two alkoxy groups bonded to the anthracene ring). The dialkoxyanthracene compound may be a 9,10-dialkoxyanthracene compound having alkoxy groups at the 9- and 10-positions of the anthracene ring. Examples of 9,10-dialkoxyanthracene compounds include 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, and 9,10-di(2-ethylhexyloxy)anthracene.

[0055] From the viewpoint of facilitating the formation of a photosensitive layer having a thickness of less than 10 μm and a light transmittance at a wavelength of 405 nm of more than 70%, the (D) component may be a combination of a pyrazoline compound and an anthracene compound. In this case, the content of the pyrazoline compound may be 0.02 parts by mass or more, 0.03 parts by mass or more, 0.05 parts by mass or more, 0.08 parts by mass or more, or 0.10 parts by mass or more, relative to 100 parts by mass of the total of the (A) component and the (B) component, and may be 0.30 parts by mass or less, 0.25 parts by mass or less, or 0.20 parts by mass or less. From the viewpoint of sensitivity, the content of the pyrazoline compound may be 0.03 parts by mass or more, 0.05 parts by mass or more, 0.08 parts by mass or more, or 0.10 parts by mass or more, relative to 100 parts by mass of the total of the (A) component and the (B) component. The content of the anthracene compound may be 0.10 parts by mass or more, 0.15 parts by mass or more, 0.20 parts by mass or more, 0.25 parts by mass or more, or 0.30 parts by mass or more, relative to 100 parts by mass of the total amount of the (A) component and the (B) component, and may be 0.60 parts by mass or less, 0.55 parts by mass or less, 0.50 parts by mass or less, 0.45 parts by mass or less, 0.40 parts by mass or less, or 0.35 parts by mass or less. The mass ratio of the anthracene compound to the pyrazoline compound (anthracene compound / pyrazoline compound) may be 1.0 or more, 1.3 or more, 1.5 or more, or 1.7 or more. The upper limit of the mass ratio of the anthracene compound to the pyrazoline compound is not particularly limited, but from the viewpoint of sensitivity, it may be 12 or less, 10 or less, 5 or less, 4 or less, 3 or less, or 2.5 or less.

[0056] From the viewpoint of facilitating the formation of a photosensitive layer having a thickness of less than 10 μm and a light transmittance at a wavelength of 405 nm of more than 70%, the (D) component may contain a high content of an anthracene compound. In this case, the content of the anthracene compound may be 0.70 parts by mass or more, 0.75 parts by mass or more, 0.80 parts by mass or more, 0.85 parts by mass or more, 0.90 parts by mass or more, or 0.95 parts by mass or more, relative to 100 parts by mass of the total amount of the (A) component and the (B) component. The upper limit of the content of the anthracene compound is not particularly limited, but may be 5.0 parts by mass or less, 3.0 parts by mass or less, 2.5 parts by mass or less, 2.0 parts by mass or less, or 1.5 parts by mass or less, relative to 100 parts by mass of the total amount of the (A) component and the (B) component.

[0057] From the viewpoint of further improving sensitivity and resolution, the content of the (D) component may be 0.10 parts by mass or more, 0.20 parts by mass or more, or 0.30 parts by mass or more, and may be 5.0 parts by mass or less, 3.0 parts by mass or less, or 1.0 part by mass or less, relative to 100 parts by mass of the total amount of the (A) component and the (B) component.

[0058] Component (E): Polymerization InhibitorThe photosensitive resin composition may further contain a polymerization inhibitor as component (E) from the viewpoint of suppressing polymerization in unexposed areas during resist pattern formation and further improving resolution. Examples of polymerization inhibitors include catechol compounds (e.g., tert-butylcatechol such as 4-tert-butylcatechol) and hindered amines (e.g., 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl).

[0059] When the photosensitive resin composition contains a catechol compound, the content of the catechol compound may be 0.001 parts by mass or more, 0.005 parts by mass or more, 0.01 parts by mass or more, 0.02 parts by mass or more, or 0.03 parts by mass or more, and may be 0.10 parts by mass or less, 0.08 parts by mass or less, 0.06 parts by mass or less, or 0.05 parts by mass or less, relative to 100 parts by mass of the total of the (A) and (B) components. When the photosensitive resin composition contains a hindered amine, the content of the hindered amine may be 0.001 parts by mass or more, 0.003 parts by mass or more, 0.005 parts by mass or more, or 0.008 parts by mass or more, and may be 0.10 parts by mass or less, 0.08 parts by mass or less, 0.06 parts by mass or less, 0.04 parts by mass or less, or 0.03 parts by mass or less, relative to 100 parts by mass of the total of the (A) and (B) components.

[0060] The content of the component (E) may be 0.001 to 0.10 parts by mass, 0.005 to 0.08 parts by mass, or 0.01 to 0.06 parts by mass relative to 100 parts by mass of the total amount of the components (A) and (B).

[0061] (Other Components) The photosensitive resin composition may further contain one or more other components in addition to the components described above. Examples of other components include hydrogen donors (such as bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leucocrystal violet, and N-phenylglycine), dyes (such as malachite green), tribromophenyl sulfone, photocoloring agents, thermal color-developing inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion promoters, leveling agents, release promoters, antioxidants, fragrances, imaging agents, and thermal crosslinking agents. The content of the other components may be 0.005 parts by mass or more, or 0.01 parts by mass or more, and may be 20 parts by mass or less, per 100 parts by mass of the total amount of component (A) and component (B).

[0062] The photosensitive resin composition may contain an organic solvent to improve handling properties and adjust viscosity and storage stability. As the organic solvent, any commonly used organic solvent can be used without particular limitation. Examples of the organic solvent include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, propylene glycol monomethyl ether, and mixed solvents thereof. For example, components (A) to (D) can be dissolved in an organic solvent to form a solution with a solids content of approximately 30 to 60% by mass (hereinafter referred to as the "coating liquid").

[0063] The thickness of the photosensitive layer is less than 10 μm. From the viewpoint of achieving better resolution, the thickness of the photosensitive layer may be 9 μm or less, 8 μm or less, 7 μm or less, or 6 μm or less. The lower limit of the thickness of the photosensitive layer is not particularly limited, but may be 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more. The thickness of the photosensitive layer is the thickness after the photosensitive layer has been dried (after the organic solvent has been volatilized if the photosensitive resin composition contains an organic solvent).

[0064] The light transmittance of the photosensitive layer at a wavelength of 405 nm is more than 70%. From the viewpoint of achieving better resolution, the light transmittance of the photosensitive layer at a wavelength of 405 nm may be 71% or more, 72% or more, or 73% or more. The upper limit of the light transmittance of the photosensitive layer at a wavelength of 405 nm is not particularly limited, but from the viewpoint of achieving better sensitivity (particularly sensitivity at a wavelength of 405 nm), it may be 95% or less, 90% or less, or 85% or less.

[0065] (Support) The support may be a polymer film having heat resistance and solvent resistance, for example, a polyester film such as a polyethylene terephthalate film, a polyethylene film, a polyolefin film such as a polypropylene film, etc. The support may be a film of a hydrocarbon polymer other than polyolefin. A film of a hydrocarbon polymer including polyolefin may have a low density, for example, 1.014 g / cm ３ The support may have the following density: The support may be a stretched film obtained by stretching the low-density hydrocarbon polymer film.

[0066] The thickness of the support may be 1 μm or more or 5 μm or more from the viewpoint of preventing damage to the support when peeling the support from the photosensitive layer, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of enabling suitable exposure even when exposure is performed through the support.

[0067] (Protective Layer) The protective layer may be a polymer film having heat resistance and solvent resistance, for example, a polyester film such as a polyethylene terephthalate film, a polyethylene film, a polyolefin film such as a polypropylene film, etc. The type of polymer film constituting the protective layer may be the same as or different from the type of polymer film constituting the support.

[0068] The thickness of the protective layer may be 1 μm or more, 5 μm or more, or 15 μm or more from the viewpoint of suppressing damage to the protective layer when the photosensitive layer and the support are laminated onto the substrate while the protective layer is peeled off, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improving productivity.

[0069] The photosensitive element can be obtained, for example, as follows: First, a photosensitive layer is formed on a support. The photosensitive layer can be formed, for example, by applying a photosensitive resin composition containing an organic solvent to form a coating layer, and then drying the coating layer. Next, a protective layer is formed on the surface of the photosensitive layer opposite the support.

[0070] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating, etc. The coating layer is dried so that the amount of organic solvent remaining in the photosensitive layer becomes, for example, 2% by mass or less, and specifically, for example, the drying is performed at 70 to 150°C for about 5 to 30 minutes.

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

[0072] The photosensitive element may be, for example, in the form of a sheet, or may be in the form of a photosensitive element roll wound around a core. In the photosensitive element roll, the photosensitive element is preferably wound with the support facing outward. The core is formed of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or the like. An end separator may be provided on the end surface of the photosensitive element roll from the viewpoint of end surface protection, or a moisture-proof end surface separator may be provided from the viewpoint of edge fusion resistance. The photosensitive element may be wrapped, for example, in a black sheet with low moisture permeability.

[0073] The photosensitive element can be suitably used for forming a fine resist pattern, and can be particularly suitably used in the method for producing a printed wiring board, which will be described later.

[0074] [Method of Forming a Resist Pattern] The method of forming a resist pattern of this embodiment includes the steps of forming a photosensitive layer on a substrate using the photosensitive element (photosensitive layer formation step), irradiating at least a portion (predetermined portion) of the photosensitive layer with actinic light to form a photocured portion (exposure step), and removing at least a portion of the unphotocured portion from the substrate (development step), and may include other steps as necessary. The resist pattern can also be referred to as a photocured product pattern of a photosensitive resin composition or a relief pattern. The method of forming a resist pattern can also be referred to as a method of manufacturing a substrate with a resist pattern.

[0075] (Photosensitive layer forming process) As a method for forming a photosensitive layer on a substrate, for example, after removing the protective layer from the photosensitive element, the photosensitive layer of the photosensitive element may be pressed onto the substrate while being heated. When a photosensitive element is used, a laminate consisting of a substrate, a photosensitive layer, and a support, which are sequentially stacked, is obtained. The substrate is not particularly limited, but is usually a circuit-forming substrate having an insulating layer and a conductor layer formed on the insulating layer, or a die pad (substrate for lead frame) such as an alloy substrate.

[0076] The photosensitive layer forming step may be carried out under reduced pressure from the viewpoint of adhesion and followability. The photosensitive layer and / or the substrate may be heated at a temperature of 70 to 130°C during pressure bonding. The pressure bonding is carried out at a pressure of about 0.1 to 1.0 MPa (1 to 10 kgf / cm ２ These conditions may be appropriately selected as required. Note that if the photosensitive layer is heated to 70 to 130°C, it is not necessary to preheat the substrate, but in order to further improve adhesion and conformability, it is also possible to preheat the substrate.

[0077] (Exposure process) In the exposure process, at least a part of the photosensitive layer formed on the substrate is irradiated with actinic rays, whereby the part irradiated with actinic rays is photocured to form a latent image. In this case, if a support is present on the photosensitive layer, and the support is transparent to actinic rays, the actinic rays can be irradiated through the support, but if the support is light-shielding, the support is removed before the photosensitive layer is irradiated with actinic rays.

[0078] Examples of the exposure method include a method of irradiating an actinic ray in an imagewise manner through a negative mask pattern called artwork (mask exposure method), a direct writing exposure method of irradiating an actinic ray in an imagewise manner, and a projection exposure method of irradiating an actinic ray projected from an image of a photomask through a lens in an imagewise manner.

[0079] As the light source of the actinic rays, a known light source can be used, for example, a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid-state laser such as a YAG laser, a semiconductor laser, etc., which effectively emit ultraviolet light and visible light, can be used.

[0080] When forming fine wiring on a panel-sized substrate, direct writing exposure, which has excellent alignment properties, is often used. In direct writing exposure, a laser diode emitting light at 405 nm is used as a light source, and therefore, from the viewpoint of productivity, a photosensitive element having high sensitivity to light with a wavelength of 405 nm is required. The photosensitive layer of the photosensitive element according to this embodiment not only has excellent resolution but also high sensitivity to light with a wavelength of 405 nm, and therefore can be suitably used in direct writing exposure.

[0081] (Development step) In the development step, at least a portion of the uncured portion (other than the cured portion) of the photosensitive layer is removed from the substrate, thereby forming a resist pattern on the substrate. If a support is present on the photosensitive layer, the support is removed, and then the area other than the cured portion (also referred to as the unexposed portion) is removed (developed). There are two development methods: wet development and dry development, with wet development being widely used.

[0082] In the case of wet development, development is carried out by a known development method using a developer suitable for the photosensitive resin composition. Examples of the development method include a dipping method, a puddle method, a spray method, brushing, scrubbing, and swinging immersion. From the viewpoint of further improving resolution, a high-pressure spray method may be used as the development method. Development may be carried out by combining two or more of these methods.

[0083] The composition of the developer is appropriately selected depending on the composition of the photosensitive resin composition. Examples of the developer include an alkaline aqueous solution and an organic solvent developer.

[0084] From the viewpoints of safety, stability, and ease of use, an alkaline aqueous solution may be used as the developer. Examples of the base for the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxide; alkali carbonates such as carbonates or bicarbonates of lithium, sodium, potassium, or ammonium; alkali metal phosphates such as potassium phosphate and sodium phosphate; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl-1,3-propanediol, 1,3-diaminopropanol-2, and morpholine.

[0085] Examples of alkaline aqueous solutions that can be used for development include a dilute solution of 0.1 to 5% by mass sodium carbonate, a dilute solution of 0.1 to 5% by mass potassium carbonate, a dilute solution of 0.1 to 5% by mass sodium hydroxide, and a dilute solution of 0.1 to 5% by mass sodium tetraborate. The pH of the alkaline aqueous solution may be in the range of 9 to 11, and the temperature can be adjusted according to the alkaline developability of the photosensitive layer. The alkaline aqueous solution may contain, for example, a surfactant, an antifoaming agent, or a small amount of an organic solvent to promote development.

[0086] Examples of organic solvents used in the alkaline aqueous solution include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0087] Examples of organic solvents used in the organic solvent developer include 1,1,1-trichloroethane, N-methyl-2-pyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. To prevent ignition, water may be added to these organic solvents in an amount of 1 to 20% by mass to form an organic solvent developer.

[0088] In the method for forming a resist pattern according to this embodiment, after removing the uncured portion in the development step, the resist is heated at about 60 to 250° C. or irradiated with 0.2 to 10 J / cm 2 as needed. ２ The method may further include a step of further hardening the resist pattern by exposing the resist pattern to light.

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

[0090] In the plating process, a conductive layer provided on a substrate is plated using a resist pattern formed on the substrate as a mask. After the plating process, the resist may be removed by removing the resist pattern as described below, and the conductive layer covered by the resist may be etched to form a conductive pattern. The plating method may be electrolytic plating or electroless plating, or may be electroless plating.

[0091] In the etching process, a resist pattern formed on a substrate is used as a mask to etch away the conductive layer provided on the substrate, thereby forming a conductive pattern. The etching method is appropriately selected depending on the conductive layer to be removed. Examples of etching solutions include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide-based etching solution.

[0092] After the etching or plating process, the resist pattern on the substrate may be removed. The resist pattern can be removed, for example, with an aqueous solution that is more strongly alkaline than the aqueous solution used in the development step. Examples of the strongly alkaline aqueous solution include a 1 to 10 mass % aqueous solution of sodium hydroxide and a 1 to 10 mass % aqueous solution of potassium hydroxide.

[0093] When the resist pattern is removed after plating, the conductor layer covered with the resist is further etched by etching to form a conductor pattern, thereby manufacturing a desired printed wiring board. The etching method used here is appropriately selected depending on the conductor layer to be removed. For example, the above-mentioned etching solution can be used.

[0094] The method for manufacturing a printed wiring board according to this embodiment can be applied to the manufacture of not only single-layer printed wiring boards but also multi-layer printed wiring boards, and can also be applied to the manufacture of printed wiring boards having small-diameter through holes.

[0095] The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples.

[0096] [Photosensitive Resin Composition] Photosensitive resin compositions of the Examples and Comparative Examples were prepared by mixing each component in the amount (parts by mass) shown in Table 1 with the component (D) in the amount (parts by mass) shown in Tables 2 and 3. The amount of each component other than the solvent shown in Tables 1 to 3 is the mass of the non-volatile content (solid content). Details of each component shown in Tables 1 to 3 are as follows.

[0097] Polymer A1: acrylic acid / styrene / dicyclopentanyl methacrylate copolymer (mass ratio: 21.0 / 72.2 / 6.8, Mw: 40,500, acid value: 156 mg KOH / g, Tg: 108°C) in toluene / propylene glycol monomethyl ether (solid content: 50% by mass); FA-321M: 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (manufactured by Resonac Co., Ltd., number of EO groups: 10 (average value)); FA-024M: PO.EO.PO-modified dimethacrylate (manufactured by Resonac Co., Ltd., number of EO groups: 6 (average value), number of PO groups: 12 (average value)); BP-2EM: ethoxylated bisphenol A dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., number of EO groups: 2.6 (average value)); B-CIM: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Hodogaya Chemical Co., Ltd.) DBA: 9,10-dibutoxyanthracene (manufactured by Kawasaki Chemical Industries, Ltd.) PZ-501D: 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)pyrazoline (manufactured by Nippon Chemical Industry Co., Ltd.) Q-TBC-5P: 4-tert-butylcatechol (manufactured by DIC Corporation) LA-7RD: 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (manufactured by ADEKA Corporation) LCV: Leuco Crystal Violet (manufactured by Yamada Chemical Industry Co., Ltd.) SF-808H: mixture of carboxybenzotriazole, 5-amino-1H-tetrazole and methoxypropanol (manufactured by Sanwa Chemical Industry Co., Ltd.) MKG: Malachite Green (Osaka Organic Chemical Industry Co., Ltd.) ACS: Acetone TLS: Toluene MAL: Methanol

[0098] [Photosensitive element] A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., trade name "FS-31") was prepared as a support. The photosensitive resin composition was applied onto the support and then dried for 10 minutes in a hot air convection dryer at 90°C to form a photosensitive layer having a thickness after drying shown in Tables 2 and 3. Subsequently, a polyethylene film (manufactured by Tamapoly Corporation, trade name "NF-15A") was laminated on the photosensitive layer as a protective layer to obtain a photosensitive element in which the support, photosensitive layer, and protective layer were laminated in this order.

[0099] [Laminate] A substrate (Ra: 150 nm) obtained by electroless copper plating on Ajinomoto Build-Up Film (registered trademark) ABF (Ajinomoto Fine-Techno Co., Ltd., product name "GL-102") was heated to 80°C, and a photosensitive element was laminated onto the copper surface of the substrate. Lamination was performed using a heat roll at 110°C, with a pressure of 0.4 MPa and a roll speed of 1.0 m / min, while peeling off the protective layer, so that the photosensitive layer of the photosensitive element was in contact with the copper surface of the copper substrate. This resulted in a laminate in which the substrate, photosensitive layer, and support were laminated in this order.

[0100] [Evaluation] (Light Transmittance) A photosensitive element was laminated on the surface of a glass slide (manufactured by Matsunami Glass Industrial Co., Ltd., white glass slide cut-off No. 1 S1126). Lamination was performed using a 110°C heat roll at a pressure of 0.4 MPa and a roll speed of 1.0 m / min, with the photosensitive layer of the photosensitive element in contact with the surface of the glass slide while peeling off the protective layer. After the photosensitive layer was laminated on the glass slide, the support was peeled off. The light transmittance of the photosensitive layer was measured using a U-3310 spectrophotometer (manufactured by Hitachi High-Tech Science Corporation) under the following measurement conditions: wavelength range: 330 to 700 nm, scan speed: 300 nm / min, scan interval: 0.50 nm, slit width: 2 nm. Baseline measurement was performed using untreated glass slides as the reference and sample. The glass slide with the photosensitive layer laminated thereon was placed in the sample holder, and an untreated glass slide was placed in the reference holder. From the obtained absorption spectrum, the light transmittance at an exposure wavelength of 405 nm was recorded and taken as the light transmittance of the photosensitive layer.

[0101] (Sensitivity) After placing a Hitachi 41-step step tablet on the support of the laminate, the photosensitive layer was exposed through the support using a direct imaging exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name: FDi-Ms) with a blue-violet laser diode having a wavelength of 405 nm as a light source, at an exposure amount (amount of irradiation energy) such that the number of remaining steps of the Hitachi 41-step step tablet was 12. The exposure amount at this time (unit: mJ / cm ２The sensitivity (photosensitivity) was evaluated by the following formula: The lower the exposure amount, the higher the sensitivity.

[0102] (Resolution) After placing a Hitachi 41-step step tablet on the support of the above laminate, the photosensitive layer was exposed through the support using a direct imaging exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name: FDi-Ms) with a blue-violet laser diode having a wavelength of 405 nm as a light source, using a drawing pattern with a line width (L) / space width (S) of 3x / x (x = 1 to 20, unit: μm, 1 μm intervals) at an exposure amount (amount of irradiation energy) such that the number of remaining steps on the Hitachi 41-step step tablet was 12.

[0103] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and the unexposed areas were removed by spraying a 1% by mass aqueous solution of sodium carbonate at 30°C for twice the minimum development time. After development, the space areas (unexposed areas) were removed without residue, and the line areas (exposed areas) were formed without meandering or chipping. The resolution was evaluated based on the minimum space width (unit: μm) in the resist pattern. The smaller this value, the better the resolution.

[0104]

[0105]

[0106]

[0107] 1... photosensitive element, 2... support, 3... photosensitive layer, 4... protective layer.

Claims

1. A photosensitive element comprising a support and a photosensitive layer formed on the support, wherein the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, the photosensitive layer having a thickness of less than 10 μm and a light transmittance of more than 70% at a wavelength of 405 nm.

2. The photosensitive element of claim 1, wherein the sensitizer comprises an anthracene compound and a pyrazoline compound.

3. The photosensitive element according to claim 1, wherein the sensitizer comprises an anthracene compound, and the content of the anthracene compound is 0.70 parts by mass or more per 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

4. A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to any one of claims 1 to 3; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

5. A method for manufacturing a printed wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method for forming a resist pattern according to claim 4, to form a conductor pattern.

Images