Photosensitive resin composition, photosensitive element, method for forming resist pattern, and method for producing printed wiring board

Abstract

A photosensitive resin composition according to one embodiment of the present invention contains: a binder polymer having a structural unit derived from acrylic acid; a photopolymerizable compound; a photopolymerization initiator; and a sensitizer. The content of the sensitizer is less than 0.01 parts by mass with respect to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

Description

Technical Field

[0001] The present invention relates to a photosensitive resin composition, a photosensitive element, a method for forming a resist pattern, and a method for manufacturing a printed wiring board. Background Art

[0002] In the field of printed wiring board manufacturing, as a resist material used in etching or plating, a photosensitive element having a photosensitive resin composition and a layer formed on a support using the photosensitive resin composition (hereinafter also referred to as a "photosensitive layer") is widely used (for example, refer to the following Patent Documents 1 and 2).

[0003] A printed wiring board is manufactured, for example, using the above-mentioned photosensitive element by the following steps. First, the photosensitive layer of the photosensitive element is laminated on a circuit forming substrate such as a copper-clad laminate. Then, a prescribed portion of the photosensitive layer is exposed via a photomask to form a photocured portion. At this time, the support is peeled off before or after exposure. Afterwards, the area outside the photocured portion of the photosensitive layer is removed with a developer to form a resist pattern on the substrate. Then, the resist pattern is used as a resist and an etching process or a plating process is performed to form a conductor pattern (conductor layer) on the substrate, and the resist is finally peeled off and removed.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-003177

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-061556 Summary of the Invention

[0008] Technical issues to be solved by the invention

[0009] In recent years, in electronic components such as inductors, a wiring pattern with a high aspect ratio is formed by increasing the thickness of the conductor layer. Therefore, a photosensitive resin composition capable of forming a thick film (for example, a film thickness of more than 30 μm) is needed. However, in previous photosensitive resin compositions, when the thickness of the photosensitive layer is increased, light is difficult to penetrate to the bottom of the photosensitive layer, resulting in a decrease in adhesion, thereby making it difficult to form a resist pattern with a high aspect ratio. Furthermore, when the thickness of the photosensitive layer is increased, there is a tendency for the developing time and the stripping time to become longer. In order to shorten the developing time and the stripping time and improve production efficiency, a photosensitive resin composition with excellent developability and stripping properties is needed.

[0010] An object of the present invention is to provide a photosensitive resin composition having excellent developability and releasability and capable of forming a resist pattern with a high aspect ratio, a photosensitive element, a method for forming a resist pattern using the same, and a method for producing a printed wiring board.

[0011] Means for solving technical problems

[0012] In order to achieve the above-mentioned object, one embodiment of the present invention relates to the following photosensitive resin composition, photosensitive element, resist pattern forming method, and printed wiring board manufacturing method.

[0013] [1] A photosensitive resin composition comprising: a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, wherein the binder polymer has a structural unit derived from acrylic acid, and the content of the sensitizer is less than 0.01 parts by mass relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

[0014] [2] The photosensitive resin composition according to [1] above, wherein

[0015] The content of the sensitizer is 0.65 parts by mass or less relative to 100 parts by mass of the total amount of the photopolymerization initiator.

[0016] [3] The photosensitive resin composition according to [1] or [2] above, wherein

[0017] The content of the sensitizer is 0.001 parts by mass or more relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

[0018] [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein

[0019] The binder polymer further includes at least one selected from the group consisting of a structural unit derived from styrene or a styrene derivative and a structural unit derived from a (meth)acrylate compound having an alicyclic structure.

[0020] [5] The photosensitive resin composition according to any one of [1] to [4] above, wherein

[0021] The sensitizer includes at least one selected from the group consisting of dialkylaminobenzophenone compounds, pyrazoline compounds, and anthracene compounds.

[0022] [6] A photosensitive element comprising a support and a photosensitive layer formed on the support using the photosensitive resin composition according to any one of [1] to [5] above.

[0023] [7] The photosensitive element according to [6] above, wherein:

[0024] The thickness of the photosensitive layer is greater than 30 μm.

[0025] [8] A method for forming a resist pattern, comprising: forming a photosensitive layer on a substrate using the photosensitive resin composition described in any one of [1] to [5] above; irradiating at least a portion of the photosensitive layer with active light to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

[0026] [9] A method for forming a resist pattern, comprising: forming a photosensitive layer on a substrate using the photosensitive element described in [6] or [7] above; irradiating at least a portion of the photosensitive layer with active light to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

[0027]

[10] A method for manufacturing a printed wiring board, comprising the step of forming a conductor pattern by etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method described in [8] or [9] above.

[0028] Effects of the Invention

[0029] According to the present invention, there can be provided a photosensitive resin composition having excellent developability and releasability and capable of forming a resist pattern with a high aspect ratio, a photosensitive element, a resist pattern forming method using the same, and a printed wiring board manufacturing method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic cross-sectional view showing one embodiment of a photosensitive element. DETAILED DESCRIPTION

[0031] Hereinafter, the embodiment for implementing the present invention will be described in detail. However, the present invention is not limited to the following embodiment.

[0032] In this specification, the word "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. Regarding the word "layer", when viewed from a top view, in addition to the structure of the shape formed on the entire surface, it also includes the structure of the shape formed on a part. The numerical range represented by "~" means a range that includes the numerical values ​​recorded before and after "~" as the minimum and maximum values, respectively. Within the numerical range described in stages in this specification, the upper limit or lower limit of the numerical range of any stage can also be replaced by the upper limit or lower limit of the numerical range of other stages. Within the numerical range described in this specification, the upper limit or lower limit of its numerical range can also be replaced by the value shown in the embodiment.

[0033] In this specification, "(meth)acrylate" refers to at least one of "acrylate" and its corresponding "methacrylate." The same applies to other similar expressions such as (meth)acryloyl.

[0034] In this specification, the amount of each component in a photosensitive resin composition refers to the total amount of each component present in the composition, unless otherwise specified. In this specification, the term "solids" refers to the non-volatile components of the photosensitive resin composition, excluding volatile substances (such as water and solvent). Specifically, "solids" refers to components other than the solvent that remain after drying the photosensitive resin composition, which will be described later. This also includes components that are liquid, syrupy, or waxy at room temperature (25°C).

[0035] [Photosensitive resin composition]

[0036] The photosensitive resin composition according to the present embodiment contains (A) a binder polymer (hereinafter sometimes referred to as "component (A)"), (B) a photopolymerizable compound (hereinafter sometimes referred to as "component (B)"), (C) a photopolymerization initiator (hereinafter sometimes referred to as "component (C)"), and (D) a sensitizer (hereinafter sometimes referred to as "component (D)"). Component (A) has a structural unit derived from acrylic acid, and the content of component (D) is less than 0.01 parts by mass relative to 100 parts by mass of the total amount of components (A) and (B). The photosensitive resin composition according to the present embodiment is excellent in developability and releasability by using such a specific binder polymer and a specific amount of a sensitizer in combination, and can form a resist pattern with a high aspect ratio, and is therefore suitable for thick film applications. The following describes in detail the various components that the photosensitive resin composition may contain.

[0037] (A) Component: Binder polymer

[0038] The photosensitive resin composition contains one or more components (A). Component (A) has a structural unit derived from acrylic acid (hereinafter sometimes referred to as a "first structural unit"). Component (A) can be produced by radical polymerization of a polymerizable monomer containing acrylic acid.

[0039] The photosensitive resin composition according to this embodiment, by containing a binder polymer having a first structural unit as component (A), can improve the developability and post-curing releasability of the photosensitive layer formed from the photosensitive resin composition. Compared to methacrylic acid, acrylic acid has a lower glass transition temperature and is more flexible. The present inventors have discovered that by using acrylic acid as a polymerizable monomer, the glass transition temperature of the resulting binder polymer can be lowered, thereby improving the developability and releasability of the photosensitive resin composition.

[0040] The content of the first structural unit in component (A) may be 15% by mass or more, 18% by mass or more, 19% by mass or more, or 20% by mass or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer, from the viewpoints of sensitivity, developability, adhesion, and releasability; and may be 27% by mass or less, 26% by mass or less, 25% by mass or less, or 24% by mass or less, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer. The content of the first structural unit in component (A) may be 15% to 27% by mass, 18% to 26% by mass, 19% to 25% by mass, or 20% to 24% by mass, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer.

[0041] From the perspective of improving the resolvability and adhesion of the photosensitive resin composition and reducing the amount of resist footing, component (A) may have a structural unit derived from styrene or a styrene derivative (hereinafter sometimes referred to as a "second structural unit"). Examples of styrene derivatives include vinyltoluene, α-methylstyrene, p-methylstyrene, and p-ethylstyrene.

[0042] The content of the second structural unit in component (A) is based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer. From the perspective of improving resolution and adhesion and reducing the amount of resist skirt generated, it can be 55% by mass or more, 60% by mass or more, 65% by mass or more, or 68% by mass or more. From the perspective of appropriately shortening the development time and preventing the generation of development residue, it can be 84% by mass or less, 80% by mass or less, 78% by mass or less, or 75% by mass or less. When component (A) has a second structural unit, from the perspective of developability, strippability, and a high aspect ratio, the mass ratio of the second structural unit to the first structural unit (mass of the second structural unit / mass of the first structural unit) can be 2.5 or more, 2.8 or more, or 3.0 or more, or 3.5 or less, or 3.3 or less.

[0043] From the viewpoint of resolution and adhesion of the photosensitive resin composition, component (A) may have a structural unit derived from a (meth)acrylate compound having an alicyclic structure (hereinafter sometimes referred to as a "third structural unit"). Examples of the (meth)acrylate having an alicyclic structure include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclopentyl (meth)acrylate, and dicyclopentyl (meth)acrylate.

[0044] The content of the third structural unit in the component (A) can be 0.5% by mass or more, 0.8% by mass or more, 1.0% by mass or more, 2.0% by mass or more, 3.0% by mass or more, or 4.0% by mass or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer, from the viewpoint of further improving the resolution and adhesion of the photosensitive resin composition; and can be 20% by mass or less, 18% by mass or less, 16% by mass or less, 14% by mass or less, or 12% by mass or less, from the viewpoint of further improving the developability of the photosensitive resin composition.

[0045] (A) component may further have a structural unit derived from a polymerizable monomer other than the above (hereinafter also referred to as "other monomers") within the scope of not affecting the effect of the present invention. As other monomers, for example, methacrylic acid, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, benzyl (meth)acrylate or its derivatives, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, β-furanyl (meth)acrylate, β-styrene (meth)acrylate, maleic acid, maleic anhydride, monoalkyl maleate, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid and propiolic acid. These can be used alone or in combination of two or more. From the viewpoint of achieving more excellent developability and releasability, the component (A) may not contain a structural unit derived from methacrylic acid.

[0046] The weight average molecular weight (Mw) of component (A) may be 20,000 or more, 25,000 or more, 30,000 or more, or 35,000 or more, or 80,000 or less, 70,000 or less, 60,000 or less, or 50,000 or less. The Mw of component (A) may be 20,000 to 80,000, 25,000 to 70,000, 30,000 to 60,000, or 35,000 to 50,000. When the Mw is 80,000 or less, the resolution and developability tend to be further improved. When the Mw is 20,000 or more, the flexibility of the cured film tends to be improved, and defects and peeling of the resist pattern tend to be less likely to occur.

[0047] Mw can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. More specifically, it can be measured under the conditions described in the Examples.

[0048] The acid value of component (A) may be 140 mgKOH / g or more, 150 mgKOH / g or more, 160 mgKOH / g or more, or 170 mgKOH / g or less, or 230 mgKOH / g or less, 220 mgKOH / g or less, 200 mgKOH / g or less, 190 mgKOH / g or less, 185 mgKOH / g or less, or 180 mgKOH / g or less. From the viewpoint of achieving superior developability and releasability, the acid value of component (A) may be 140 to 230 mgKOH / g, 140 to 200 mgKOH / g, 150 to 190 mgKOH / g, 160 to 185 mgKOH / g, or 170 to 180 mgKOH / g. When the acid value of component (A) is 140 mgKOH / g or greater, the development time can be more effectively suppressed. When it is 200 mgKOH / g or less, the developer resistance (adhesion) of the cured product of the photosensitive resin composition can be more easily improved. The acid value of component (A) can be adjusted by the structural unit derived from acrylic acid. The acid value of component (A) can be measured according to JIS K6901:2008 5.3.2.

[0049] The glass transition temperature (Tg) of component (A) may be 80°C or higher, 90°C or higher, 95°C or higher, or 100°C or higher, or 120°C or lower, 113°C or lower, 112°C or lower, 111°C or lower, or 110°C or lower. The Tg of component (A) may be 80°C to 120°C, 80°C to 113°C, 90°C to 112°C, 95°C to 111°C, or 100°C to 110°C. When the Tg of component (A) is 80°C or higher, the lamination properties of the photosensitive layer formed from the photosensitive resin composition are easily improved. When it is 120°C or lower, the adhesion, resolution, and storage stability of the photosensitive resin composition are easily improved. The Tg of component (A) is a value determined according to Fox's equation and can be calculated based on the mass of each polymerizable monomer constituting component (A) and the Tg of the homopolymer of each polymerizable monomer.

[0050] The content of component (A) relative to 100 parts by mass of the total amount of component (A) and component (B) may be 20 parts by mass or more, 30 parts by mass or more, 40 parts by mass or more, or 50 parts by mass or more from the viewpoint of excellent film formability, and may be 80 parts by mass or less, 70 parts by mass or less, or 60 parts by mass or less from the viewpoint of further improving sensitivity and resolution.

[0051] Component (B): Photopolymerizable compound

[0052] The photosensitive resin composition contains one or more components (B). Component (B) may be a compound that undergoes photopolymerization, for example, a compound having an ethylenically unsaturated bond. Component (B) may also contain a polyfunctional monomer having two or more reactive groups that undergo free radical reactions. From the perspectives of developability, resolution, and post-curing peelability, component (B) may contain a bisphenol A (meth)acrylate compound.

[0053] Examples of bisphenol A (meth)acrylate compounds include 2,2-bis(4-((meth)acryloyloxypolyethoxy)phenyl)propane, 2,2-bis(4-((meth)acryloyloxypolypropoxy)phenyl)propane, 2,2-bis(4-((meth)acryloyloxypolybutoxy)phenyl)propane, and 2,2-bis(4-((meth)acryloyloxypolyethoxypolypropoxy)phenyl)propane. From the perspective of resolution and releasability, component (B) may contain 2,2-bis(4-((meth)acryloyloxypolyethoxy)phenyl)propane. As 2,2-bis(4-((meth)acryloyloxypolyethoxy)phenyl)propane, a compound having 10 or more ethylene oxides or a compound having less than 10 ethylene oxides may be used, or a compound having 10 or more ethylene oxides and a compound having less than 10 ethylene oxides may be used in combination. Examples of 2,2-bis(4-((meth)acryloyloxypolyethoxy)phenyl)propane include 2,2-bis(4-((meth)acryloyloxypentaethoxy)phenyl)propane and 2,2-bis(4-((meth)acryloyloxydiethoxy)phenyl)propane.

[0054] From the perspective of resolution, the content of the bisphenol A (meth)acrylate compound may be 20% by mass or more, 40% by mass or more, 60% by mass or more, or 80% by mass or more, based on the total amount of component (B), or may be 100% by mass or less, or 95% by mass or less. When 2,2-bis(4-((meth)acryloyloxypolyethoxy)phenyl)propane is used as the bisphenol A (meth)acrylate compound, the content of the compound having 10 or more ethylene oxide groups, based on the total amount of component (B), may be 20% by mass or more, 40% by mass or more, 60% by mass or more, or 70% by mass or less, or may be 100% by mass or less, 95% by mass or less, or 90% by mass or less.

[0055] From the perspective of resolution and flexibility, component (B) may include an α,β-unsaturated ester compound obtained by reacting a polyol with an α,β-unsaturated carboxylic acid. Examples of the α,β-unsaturated ester compound include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyalkylene glycol di(meth)acrylates such as EO-modified polypropylene glycol, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO / PO-modified trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate.

[0056] From the viewpoint of sensitivity and adhesion, component (B) may contain a compound having three or more (meth)acryloyl groups. Examples of the compound having three or more (meth)acryloyl groups include trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO / PO-modified trimethylolpropane tri(meth)acrylate, EO-modified pentaerythritol tetra(meth)acrylate, EO-modified ditrimethylolpropane tetra(meth)acrylate, and EO-modified dipentaerythritol hexa(meth)acrylate.

[0057] The content of the α,β-unsaturated ester compound may be 20% or 30% by mass based on the total amount of the component (B) from the viewpoint of flexibility, and may be 70% or 60% by mass from the viewpoint of resolution.

[0058] The photosensitive resin composition may contain other photopolymerizable compounds other than the bisphenol A-type (meth)acrylate compound and the α,β-unsaturated ester compound as the component (B).

[0059] Examples of other photopolymerizable compounds include nonylphenoxy polyethylene oxyacrylate, phthalic acid compounds, alkyl (meth)acrylates, and photopolymerizable compounds having at least one cationically polymerizable cyclic ether group in the molecule (such as oxetane compounds). From the perspectives of resolution, adhesion, resist shape, and post-curing peelability, the other photopolymerizable compound may be at least one selected from the group consisting of nonylphenoxy polyethylene oxyacrylate and phthalic acid compounds.

[0060] Examples of the nonylphenoxy polyethyleneoxy acrylate include nonylphenoxytriethyleneoxy acrylate, nonylphenoxytetraethyleneoxy acrylate, nonylphenoxypentaethyleneoxy acrylate, nonylphenoxyhexaethyleneoxy acrylate, nonylphenoxyheptaethyleneoxy acrylate, nonylphenoxyoctaethyleneoxy acrylate, nonylphenoxynonaeethyleneoxy acrylate, nonylphenoxydecaethyleneoxy acrylate, and nonylphenoxyundeethyleneoxy acrylate.

[0061] Examples of phthalic acid compounds include γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl phthalate (also known as 3-chloro-2-hydroxypropyl-2-(meth)acryloyloxyethyl phthalate), β-hydroxyethyl-β'-(meth)acryloyloxyethyl phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl phthalate.

[0062] When component (B) contains other photopolymerizable compounds, the content of other photopolymerizable compounds may be 1% by mass or more, 3% by mass or more, or 5% by mass or less, or 30% by mass or less, or 25% by mass or less, based on the total amount of component (B), from the viewpoints of resolution, adhesion, resist shape, and peelability after curing.

[0063] Among the above compounds, component (B) may contain a compound having a total of 2 to 40 ethylene oxide (EO groups) and / or propylene oxide (PO groups) in the molecule from the viewpoint of adhesion and resolution. From the viewpoint of adhesion and resolution, the total number of EO groups and / or PO groups may be 2 to 40 or 2 to 30.

[0064] From the viewpoint of adhesion and resolution, the content of the compound having 2 to 40 EO and / or PO groups in total based on the total amount of component (B) may be 2 to 15 mass %, 4 to 12 mass %, or 5 to 8 mass %.

[0065] The content of component (B) is based on the total solid content of the photosensitive resin composition. From the viewpoint of sensitivity and resolution, it can be 3% by mass or more, 10% by mass or more, or 25% by mass or more. From the viewpoint of film formability, it can be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

[0066] Component (C): Photopolymerization initiator

[0067] The photosensitive resin composition contains one or more components (C). The component (C) is not particularly limited as long as it can polymerize the component (B), and can be appropriately selected from commonly used photopolymerization initiators.

[0068] Examples of the component (C) include hexaarylbiimidazole compounds; benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino- Aromatic ketone compounds such as acetone-1; quinone compounds such as alkyl anthraquinone; benzoin ether compounds such as benzoin alkyl ether; benzoin compounds such as benzoin and alkyl benzoin; benzyl derivatives such as benzyl dimethyl ketal; and phosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethylbenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0069] From the perspective of suppressing the permeation of the photosensitizer into the polyethylene film, component (C) may contain a hexaarylbiimidazole compound. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. The hydrogen atoms bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with halogen atoms (chlorine atoms, etc.).

[0070] The hexaarylbiimidazole compound may be a 2,4,5-triaryl imidazole dimer. Examples of the 2,4,5-triaryl imidazole dimer include 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-bis-(m-methoxyphenyl) imidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer. From the perspective of further suppressing the permeation of the photosensitizer into the polyethylene film, the hexaarylbiimidazole compound is preferably a 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, and more preferably 2,2-bis(o-chlorophenyl)-4,5-4',5'-tetraphenyl-1,2'biimidazole.

[0071] The content of the hexaarylbiimidazole compound may be 90% by mass or more, 95% by mass or more, or 99% by mass or more based on the total amount of the component (C). The component (C) may consist solely of the hexaarylbiimidazole compound.

[0072] From the viewpoint of sensitivity and adhesion, the content of component (C) may be 0.1% by mass or more, 0.5% by mass or more, or 1.0% by mass or more, or 20% by mass or less, 10% by mass or less, or 5% by mass or less, based on the total solid content of the photosensitive resin composition.

[0073] (D) Component: Sensitizer

[0074] The photosensitive resin composition contains one or more components (D). Examples of the component (D) include dialkylaminobenzophenone compounds, pyrazoline compounds, anthracene compounds, coumarin compounds, xanthone compounds, thioxanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, naphthalimide compounds, triarylamine compounds, and aminoacridine compounds.

[0075] Examples of the dialkylaminobenzophenone compound include 4,4′-bis(dimethylamino)benzophenone and 4,4′-bis(diethylamino)benzophenone.

[0076] Examples of the pyrazoline compound include 1-(4-methoxyphenyl)-3-styrene-5-phenyl-pyrazoline, 1-phenyl-3-(4-methoxystyrene)-5-(4-methoxyphenyl)-pyrazoline, 1,5-bis-(4-methoxyphenyl)-3-(4-methoxystyrene)-pyrazoline, 1-(4-isopropylphenyl)-3-styrene-5-phenyl-pyrazoline, 1-phenyl-3-(4-isopropylstyrene)-5-(4-isopropylphenyl)-pyrazoline, 1,5-bis-(4-isopropylphenyl)-3-(4-isopropylstyrene)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-tert-butylstyrene)-5-(4-tert-butylphenyl)-pyrazoline, and 1-(4-methoxyphenyl)-3-(4-tert-butylstyrene)-5-(4-tert-butylphenyl)-pyrazoline. 4-tert-butyl-phenyl)-3-(4-methoxystyrene)-5-(4-methoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-tert-butyl-styrene)-5-(4-tert-butyl-phenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(4-isopropyl-styrene)-5-(4-isopropyl-phenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(4-isopropylstyrene)-5-(4-isopropylphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(4-methoxystyrene)-5-(4-methoxyphenyl)-pyrazoline, 1-phenyl-3-(3,5-dimethoxystyrene)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(3,4-dimethoxystyrene)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,6-dimethoxystyrene)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,5-dimethoxystyrene)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,3-dimethoxystyrene)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-phenyl-3-(2,4-dimethoxystyrene)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(3,5-dimethoxystyrene)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-( 4-methoxyphenyl)-3-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,6-dimethoxyphenyl)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,5-dimethoxyphenyl)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,3-dimethoxyphenyl)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-methoxyphenyl)-3-(2,4-dimethoxyphenyl)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,5-dimethoxystyrene)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(3,4-dimethoxystyrene)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,6-dimethoxystyrene)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,5-dimethoxystyrene)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,3-dimethoxystyrene)-5-(2,3-dimethoxyphenyl)-pyrazoline, 1-(4-tert-butyl-phenyl)-3-(2,4-dimethoxystyrene)-5-(2,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl- phenyl)-3-(3,5-dimethoxystyrene)-5-(3,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(3,4-dimethoxystyrene)-5-(3,4-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,6-dimethoxystyrene)-5-(2,6-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,5-dimethoxystyrene)-5-(2,5-dimethoxyphenyl)-pyrazoline, 1-(4-isopropyl-phenyl)-3-(2,3-dimethoxystyrene)-5-(2,3-dimethoxyphenyl)-pyrazoline and 1-(4-isopropyl-phenyl)-3-(2,4-dimethoxystyrene)-5-(2,4-dimethoxyphenyl)-pyrazoline. ,

[0077] 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-anthracenecarboxaldehyde, 9,10-dimethylanthracene, 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 9,10-dipentyloxyanthracene, 9,10-di(2-ethylhexyloxy)anthracene, 9,10-diphenylanthracene, 2-bromo-9,10-diphenylanthracene, 9-(4-bromophenyl)-10-phenylanthracene, 10-methyl-9-anthracenecarboxaldehyde, and 1,4,9,10-tetrahydroxyanthracene.

[0078] Examples of the coumarin compound include 3-benzoyl-7-diethylaminocoumarin, 7-diethylamino-4-methylcoumarin, and 3,3′-carbonylbis(7-diethylaminocoumarin).

[0079] From the viewpoints of adhesion, resolution, and high aspect ratio, component (D) may contain at least one selected from the group consisting of dialkylaminobenzophenone compounds, pyrazoline compounds, and anthracene compounds. From the viewpoint of releasability, component (D) may contain a dialkylaminobenzophenone compound.

[0080] From the viewpoints of adhesion, resolution, and high aspect ratio, the content of component (D) is less than 0.01 parts by mass, and may be 0.009 parts by mass or less, 0.008 parts by mass or less, 0.007 parts by mass or less, or 0.006 parts by mass or less, relative to 100 parts by mass of the total of components (A) and (B). From the viewpoint of sensitivity, the content of component (D) may be 0.001 parts by mass or more, 0.002 parts by mass or more, 0.003 parts by mass or more, or 0.004 parts by mass or more, relative to 100 parts by mass of the total of components (A) and (B).

[0081] From the viewpoint of adhesion, resolution, and high aspect ratio, the content of component (D) can be 0.65 parts by mass or less, 0.60 parts by mass or less, 0.50 parts by mass or less, 0.40 parts by mass or less, 0.30 parts by mass or less, or 0.20 parts by mass or less relative to 100 parts by mass of the total amount of component (C).

[0082] (E) ingredient: polymerization inhibitor

[0083] To suppress polymerization of unexposed areas during resist pattern formation and improve resolution, the photosensitive resin composition may further contain component (E): a polymerization inhibitor. Examples of the polymerization inhibitor include 4-tert-butylcatechol and 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl.

[0084] 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).

[0085] The photosensitive resin composition may further contain one or more other ingredients other than the above-mentioned ingredients. As other ingredients, hydrogen donors (bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leuco crystal violet, N-phenylglycine, etc.), dyes (malachite green, etc.), photochromic agents (tribromophenyl sulfone, leuco crystal violet, etc.), thermochromic inhibitors, plasticizers (p-toluenesulfonamide, etc.), pigments, fillers, defoamers, flame retardants, stabilizers, adhesion-imparting agents, leveling agents, peeling accelerators, antioxidants, fragrances, imaging agents, thermal crosslinking agents, etc. can be mentioned. The content of other ingredients can be 0.005 mass parts or more or 0.01 mass parts or less relative to 100 mass parts of the total amount of component (A) and component (B), or can be 20 mass parts or less.

[0086] From the perspective of adjusting viscosity, the photosensitive resin composition may further contain one or more organic solvents. Examples of organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, and propylene glycol monomethyl ether. The content of the organic solvent may be 40% by mass or greater, or 70% by mass or less, based on the total amount of the photosensitive resin composition.

[0087] The photosensitive resin composition can be used to form a resist pattern, and can be particularly used in a method for producing a wiring board to be described later.

[0088] [Photosensitive element]

[0089] The photosensitive element according to this embodiment comprises a support and a photosensitive layer formed on the support using the above-described photosensitive resin composition. The solid content of each component in the photosensitive layer, excluding volatile substances, can be within the numerical range of the solid content of each component in the above-described photosensitive resin composition. When using the photosensitive element according to this embodiment, after laminating the photosensitive layer on the substrate, exposure can be performed without removing the support. Figure 1 1 is a schematic cross-sectional view of a photosensitive element according to one embodiment. Figure 1 As shown, the photosensitive element 1 includes a support 2, a photosensitive layer 3 made of the above-mentioned photosensitive resin composition formed on the support 2, and other layers such as a protective layer 4 provided as needed.

[0090] The support 2 and the protective layer 4 can each be a heat-resistant and solvent-resistant polymer film, for example, a polyester film such as polyethylene terephthalate film, a polyolefin film such as polyethylene film, or a polypropylene film. The support 2 and the protective layer 4 can each be a film of a hydrocarbon polymer other than polyolefin. The film of a hydrocarbon polymer including polyolefin can have a low density, for example, 1.014 g / cm 3The support 2 and the protective layer 4 can each be a stretched film formed by stretching the low-density hydrocarbon polymer film. The type of polymer film constituting the protective layer 4 can be the same as or different from the type of polymer film constituting the support 2.

[0091] These polymer films are commercially available as polyethylene terephthalate films such as PS series (e.g., PS-25) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by TAMAPOLY CO., LTD., or polypropylene films such as those manufactured by OJIPAPER CO., LTD. (e.g., ALPHAN MA-410, E-200C) and SHIN-ETSU FILM CO., LTD.

[0092] Regarding the thickness of the support 2, from the viewpoint of being able to suppress damage to the support 2 when peeling off the photosensitive layer 3, it can be greater than 1 μm or greater than 5 μm, and from the viewpoint of being able to appropriately perform exposure when exposure is performed through the support 2, it can be less than 100 μm, less than 50 μm or less than 30 μm.

[0093] Regarding the thickness of the protective layer 4, from the perspective of suppressing damage to the protective layer 4 when the protective layer 4 is peeled off and the photosensitive layer 3 and the support body 2 are laminated on the substrate, it can be greater than 1 μm, greater than 5 μm or greater than 15 μm. From the perspective of improving productivity, it can be less than 100 μm, less than 50 μm or less than 30 μm.

[0094] The photosensitive layer 3 is formed using the above-mentioned photosensitive resin composition. The thickness of the photosensitive layer 3 after drying (after volatilization of the organic solvent when the photosensitive resin composition contains an organic solvent) can be 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, or 80 μm or more from the perspective of forming a thick film resist pattern, and can be 500 μm or less, 450 μm or less, 400 μm or less, 350 μm or less, or 300 μm or less from the perspective of adhesion, resolution, and a high aspect ratio.

[0095] The photosensitive element 1 can be obtained, for example, as follows. First, a photosensitive layer 3 is formed on a support 2. The photosensitive layer 3 can be formed, for example, by applying a photosensitive resin composition containing an organic solvent to form a coating layer and drying the coating layer. Next, a protective layer 4 is formed on the surface of the photosensitive layer 3 opposite the support 2.

[0096] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating. The coating layer is dried so that the amount of the organic solvent remaining in the photosensitive layer 3 is, for example, 2% by mass or less. Specifically, the drying is performed at 70 to 150° C. for about 5 to 30 minutes.

[0097] In another embodiment, the photosensitive element may not include the protective layer, and may further include other layers such as a buffer layer, an adhesive layer, a light absorbing layer, and a gas barrier layer.

[0098] The photosensitive element 1 may be in the form of a sheet or a roll of a photosensitive element wound around a core. In the photosensitive element roll, the photosensitive element 1 is preferably wound with the support 2 facing outward. The core may be made of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, or acrylonitrile-butadiene-styrene copolymer. To protect the ends, the photosensitive element roll may be provided with end spacers, or to prevent edge fusion, moisture-proof end spacers may be provided. The photosensitive element 1 may be packaged, for example, with a black sheet having low moisture permeability.

[0099] The photosensitive element 1 can be suitably used for forming a resist pattern, and is particularly suitable for a method of manufacturing a printed wiring board to be described later.

[0100] [Method for Forming Resist Pattern]

[0101] The method for forming a resist pattern according to the present embodiment includes: a process of forming a photosensitive layer on a substrate using the above-mentioned photosensitive resin composition or the above-mentioned photosensitive element (photosensitive layer forming process); a process of irradiating at least a portion (prescribed portion) of the above-mentioned photosensitive layer with active light to form a photocured portion (exposure process); and a process of removing at least a portion of the unphotocured portion of the above-mentioned photosensitive layer from the above-mentioned substrate (development process), and may also include other processes as needed. The resist pattern is also called a photocured pattern of a photosensitive resin composition, and is also called a relief pattern. The method for forming a resist pattern is also called a method for manufacturing a substrate with a resist pattern.

[0102] (Photosensitive layer forming step)

[0103] As a method for forming a photosensitive layer on a substrate, for example, the photosensitive resin composition may be applied and dried, or the protective layer may be removed from the photosensitive element and then the photosensitive layer of the photosensitive element may be heated and then pressed against the substrate. When a photosensitive element is used, a laminated body can be obtained by sequentially laminating a substrate, a photosensitive layer, and a support. The substrate is not particularly limited, but a die pad (lead frame substrate) such as a circuit forming substrate or an alloy substrate having an insulating layer and a conductive layer formed on the insulating layer can generally be used.

[0104] When using a photosensitive element, the photosensitive layer formation process can be carried out under reduced pressure from the perspective of adhesion and followability. The heating of the photosensitive layer and / or substrate during pressure bonding can be carried out at a temperature of 70 to 130°C. Pressure bonding can be carried out at about 0.1 to 1.0 MPa (1 to 10 kgf / cm 2 The substrate is heated to 70-130°C, but preheating the substrate is not necessary. However, preheating the substrate may be performed to further improve adhesion and tracking properties.

[0105] (Exposure Process)

[0106] During the exposure process, at least a portion of the photosensitive layer formed on the substrate is irradiated with active light. The portion exposed to the active light is photocured, forming a latent image. If a support is present on the photosensitive layer, the active light can be irradiated through the support if the support is transmissive to the active light. However, if the support is light-blocking, the active light can be irradiated to the photosensitive layer after the support is removed.

[0107] Examples of the exposure method include a method of irradiating active light in an image-like manner using a direct writing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method, a method of irradiating active light in an image-like manner using a negative or positive mask pattern called an original image (mask exposure method), and a method of irradiating active light in an image-like manner using a projection exposure method.

[0108] As the light source of the active light, 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 laser such as a YAG laser, an ultraviolet light such as a semiconductor laser, or a light source that effectively radiates visible light.

[0109] (Development Process)

[0110] In the development step, at least a portion of the unphotocured portion (other than the photocured portion) of the photosensitive layer is removed from the substrate, thereby forming a resist pattern on the substrate.

[0111] When a support is present on the photosensitive layer, the support is removed and then the area other than the photocured portion (also referred to as the unexposed portion) is removed (developed). There are two development methods: wet development and dry development, but wet development is widely used.

[0112] When wet development is employed, a developer corresponding to the photosensitive resin composition can be used to develop the image using a known development method. Examples of development methods include dipping, capstan immersion, spraying, brushing, patting, scrubbing, and shaking immersion. From the perspective of resolution, a high-pressure spray method can be used. Development can also be performed using a combination of two or more of these methods.

[0113] The composition of the developer can be appropriately selected according to the composition of the photosensitive resin composition. Examples of the developer include alkaline aqueous solutions and organic solvent developers.

[0114] From the perspectives of safety, stability, and good operability, an alkaline aqueous solution may also be used as a developer. Examples of the base in the alkaline aqueous solution include alkali hydroxides such as lithium, sodium, or potassium hydroxides; alkali carbonates such as lithium, sodium, potassium, or ammonium carbonates or bicarbonates; 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, morpholine, and the like.

[0115] Examples of the alkaline aqueous solution used for development include a dilute solution of 0.1-5% by mass sodium carbonate, a dilute solution of 0.1-5% by mass potassium carbonate, a dilute solution of 0.1-5% by mass sodium hydroxide, and a dilute solution of 0.1-5% by mass sodium tetraborate. The pH of the alkaline aqueous solution can be set within a range of 9-11, and the temperature can be adjusted according to the alkali developability of the photosensitive layer. For example, a surfactant, a defoaming agent, or a small amount of an organic solvent may be mixed into the alkaline aqueous solution to promote development.

[0116] Examples of the organic solvent used in the alkaline aqueous solution include acetone, ethyl acetate, alkoxyethanol having an alkoxy group having 1 to 4 carbon atoms, ethanol, isopropyl alcohol, butanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

[0117] Examples of organic solvents used in organic solvent developers include 1,1,1-trichloroethane, N-methyl-2-pyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. To prevent ignition, water is added to these organic solvents in an amount ranging from 1 to 20% by mass to prepare the organic solvent developer.

[0118] The resist pattern forming method of the present embodiment may further include the following steps: after removing the uncured portion in the development step, heating at about 60 to 250° C. or heating at 0.2 to 10 J / cm 2The resist pattern is further cured by exposure of about 100 nm.

[0119] [Manufacturing method of printed wiring board]

[0120] The method for manufacturing a printed wiring board according to this embodiment includes a step of forming a conductor pattern by etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method described above, and may also include other steps such as a resist pattern removal step as needed.

[0121] In the plating process, a conductive layer provided on the substrate is plated using a resist pattern formed on the substrate as a mask. After the plating process, the resist can be removed by removing the resist pattern as described below, and the conductive layer covered by the resist can be further etched to form a conductive pattern. The plating method can be electrolytic plating or electroless plating, and electroless plating is also possible.

[0122] Meanwhile, in the etching process, a conductive layer provided on the substrate is etched away using a resist pattern formed on the substrate as a mask to form a conductive pattern. The etching method can be appropriately selected depending on the conductive layer to be removed. Examples of etching solutions include cupric chloride solutions, ferric chloride solutions, alkaline etching solutions, and hydrogen peroxide-based etching solutions.

[0123] After the etching or plating process, the resist pattern on the substrate can also be removed. The resist pattern can be removed, for example, by using an aqueous solution that is more alkaline than the alkaline aqueous solution used in the development step. Examples of the strongly alkaline aqueous solution include a 1-10% by mass sodium hydroxide aqueous solution or a 1-10% by mass potassium hydroxide aqueous solution.

[0124] When the resist pattern is removed after plating, the conductive layer covered by the resist is further etched to form a conductive pattern, thereby manufacturing a desired printed wiring board. The etching method in this case can be appropriately selected depending on the conductive layer to be removed. For example, the above-mentioned etching solution can be used.

[0125] The method for manufacturing a printed wiring board according to the present embodiment can be applied to the manufacture of not only a single-layer printed wiring board but also a multilayer printed wiring board, and can also be applied to the manufacture of a printed wiring board having a through hole with a small diameter, and the like.

[0126] Example

[0127] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0128] [Synthesis of Binder Polymer]

[0129] As a polymerizable monomer, a compound having the homopolymer Tg shown below was prepared.

[0130] AA: Acrylic acid (Tg: 106°C)

[0131] MAA: Methacrylic acid (Tg: 228°C)

[0132] ST: Styrene (Tg: 100°C)

[0133] TCDMA: dicyclopentyl methacrylate (Tg: 175°C)

[0134] HEMA: Hydroxyethyl methacrylate (Tg: 55°C)

[0135] BZMA: benzyl methacrylate (Tg: 54°C)

[0136] (Synthesis example 1)

[0137] A mixture (x) was prepared by mixing 100.4 g of acrylic acid (AA), 308.9 g of styrene (ST), and 29.7 g of dicyclopentyl methacrylate (TCDMA) (mass ratio of AA / ST / TCDMA = 23 / 70 / 7) as polymerizable monomers, 2.2 g of azobisisobutyronitrile (AIBN) as a thermal radical polymerization initiator, and 129.5 g of propylene glycol monomethyl ether as a solvent. A solution (a) was prepared by dissolving 5.5 g of AIBN in 26.3 g of propylene glycol monomethyl ether.

[0138] To a flask equipped with a stirring device, a dropping funnel, a capacitor, a thermometer and a gas inlet tube, 45.6 g of propylene glycol monomethyl ether and 175.1 g of toluene were added, and the mixture was stirred while replacing the gas under a nitrogen atmosphere and heated to 80°C. Then, the mixture (x) was added dropwise to the flask over 2 hours. After the addition was completed, the mixture was stirred at 80°C for 2 hours, and then the solution (a) was added and stirred for a further 3 hours. Then, while continuing to stir, the solution in the flask was heated to 100°C over 20 minutes, and then stirred at 100°C for 2 hours. Then, 93.7 g of propylene glycol monomethyl ether and 74.3 g of toluene were added, and the mixture was cooled to room temperature while stirring to obtain a solution of the binder polymer (A-1) (solid content: 50% by mass).

[0139] (Synthesis Examples 2 to 5)

[0140] Except that the type and amount of the polymerizable monomer of the mixture (x) were changed to the polymerizable monomer and mass ratio shown in Table 1, under the same conditions as in Synthesis Example 1, solutions of binder polymers (A-2) to (A-5) (solid content: 50% by mass) were obtained.

[0141] [Table 1]

[0142]

[0143] (weight average molecular weight)

[0144] As a sample for Mw measurement, the polymer solution was dissolved in tetrahydrofuran (THF) to prepare a 0.2 mass% THF solution. The Mw was derived by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene. The GPC conditions are shown below.

[0145] Measuring apparatus: Shodex (registered trademark) GPC-101 (manufactured by Resonac Holdings Corporation)

[0146] Detector: Differential refractometer Shodex RI-71S (manufactured by Resonac Holdings Corporation)

[0147] Chromatographic columns: Shodex LF-804+LF-804 (manufactured by Resonac Holdings Corporation)

[0148] Column temperature: 40°C

[0149] Eluent: THF

[0150] Flow rate: 1 mL / min

[0151] (Glass transition temperature)

[0152] The Tg of the binder polymer was calculated from the Fox formula.

[0153] (Acid value)

[0154] The acid value of the binder polymer was measured by a neutralization titration method in accordance with JIS K6901:2008 5.3.2.

[0155] [Photosensitive resin composition]

[0156] A photosensitive resin composition was prepared by mixing the components in the amounts (parts by mass) listed in Table 2 with the amounts (parts by mass) listed in Tables 3 and 4 for the sensitizers (EAB: 4,4'-bis(diethylamino)benzophenone (manufactured by HODOGAYA CHEMICAL CO., LTD.); and pyrazoline: 1-phenyl-3-(4-methoxyphenyl)-5-(4-methoxyphenyl)pyrazoline (manufactured by NIPPON CHEMICAL WORKS CO., LTD., trade name "PZ-501D")) relative to 57.0 parts by mass of the solid content of the binder polymer solution. Details of the components listed in Table 2 are as follows.

[0157] [Table 2]

[0158] FA-321M 34.5 FA-024M 2.5 BP-2EM 6.0 B-CIM 2.9 Q-TBC-5P 0.04 LA-7RD 0.01 LCV 0.3 SF-808H 1.0 MKG 0.03 acetone 10 Toluene 10 Methanol 6

[0159] (Photopolymerizable compound)

[0160] FA-321M: 2,2-bis(4-(methacryloyloxypentaethoxy)phenyl)propane (manufactured by Resonac Holdings Corporation)

[0161] FA-024M: EOPO-modified dimethacrylate (manufactured by Resonac Holdings Corporation)

[0162] BP-2EM: 2,2-bis(4-(methacryloyloxydiethoxy)phenyl)propane (manufactured by KYOEISHA CHEMICAL Co., LTD.)

[0163] (Photopolymerization initiator)

[0164] B-CIM: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Hampford)

[0165] (Polymerization Inhibitor)

[0166] Q-TBC-5P: 4-tert-butylcatechol (manufactured by DIC Corporation)

[0167] LA-7RD: 2,2,6,6-tetramethyl-4-hydroxypiperidin-1-oxyl (manufactured by ADEKA CORPORATION)

[0168] (Photochromic agent)

[0169] LCV: Leuco crystal violet (manufactured by YAMADA CHEMICAL CO., LTD.)

[0170] (Adhesion-imparting agent)

[0171] SF-808H: A mixture of carboxybenzotriazole, 5-amino-1H-tetrazole, and methoxypropanol (manufactured by SANWA KASEICORP)

[0172] (dye)

[0173] MKG: Malachite green (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.)

[0174] [Photosensitive element]

[0175] A 16 μm thick polyethylene terephthalate film (manufactured by TORAY INDUSTRIES, INC., trade name "QS-69") was prepared as a support. After coating the support with a photosensitive resin composition, the composition was dried in a hot air convection dryer at 80°C and 120°C, respectively, to form a photosensitive layer having the film thicknesses shown in Tables 3 and 4 after drying. A polyethylene film (manufactured by TAMAPOLY CO., LTD., trade name "NF-15") was laminated onto the photosensitive layer as a protective layer, yielding a photosensitive element in which a support, a photosensitive layer, and a protective layer were laminated in this order.

[0176] [Laminated body]

[0177] A copper-clad laminate (MCL-E-679, manufactured by Resonac Holdings Corporation) made of glass epoxy resin and laminated on both sides with copper foil (thickness: 35 μm) was surface treated by water washing, acid washing, and water washing, and then dried with airflow. The surface-treated copper-clad laminate was heated to 80°C, and while the protective layer was peeled off, a photosensitive element was laminated onto the copper-clad laminate so that the photosensitive layer was in contact with the copper surface. This produced a laminated body composed of the copper-clad laminate, photosensitive layer, and support laminated in this order. Lamination was performed using a heated roller at 110°C, with a pressing pressure of 0.4 MPa and a roller speed of 1.05 m / min.

[0178] [evaluate]

[0179] (Minimum development time)

[0180] The above-mentioned laminate was cut into 5 cm squares to obtain a test piece for measuring the minimum developing time. After peeling the support from the test piece, the unexposed photosensitive layer was spray-developed using a 1% by mass sodium carbonate aqueous solution at 30°C at a pressure of 0.15 MPa. The shortest time that can be visually confirmed to remove an unexposed portion of more than 1 mm was set as the minimum developing time (unit: second). A full cone was used for the spray developing nozzle. The distance between the above-mentioned test piece and the front end of the nozzle was 6 cm, and the center of the test piece was configured to coincide with the center of the nozzle. The shorter the minimum developing time, the better the developability. The results are shown in Tables 3 and 4.

[0181] (Adhesion)

[0182] A test pattern with a line width (L) / space width (S) of x / 3x (x = 1 to 100, unit: μm, varying at intervals of 1 μm) as a negative mask for evaluating adhesion was placed on the support body of the above-mentioned laminate, and exposure was performed using a parallel light exposure device (manufactured by ORC MANUFACTURING CO., LTD., trade name "EXM-1201") using a high-pressure mercury lamp as a light source, with an exposure amount such that the number of remaining stages of a Hitachi 41-stage step tablet became 14 stages.

[0183] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and a 1% by mass sodium carbonate aqueous solution was sprayed at 30 ° C for 50 seconds to remove the unexposed portion. After development, the minimum value (unit: μm) in the line width of the resist pattern formed by removing the gap portion (unexposed portion) without residue and the line portion (exposed portion) without snaking and defects was evaluated for adhesion. The smaller the value, the better the adhesion. In addition, the ratio of the thickness of the resist pattern to the value (the aspect ratio of the resist pattern) was calculated. The results are shown in Tables 3 and 4.

[0184] (resolution)

[0185] A resolution evaluation mask with a grid-like pattern of dots with diameters of 1 to 100 μm was placed on the support of the laminate. Exposure was then performed using a parallel light exposure system (manufactured by ORC MANUFACTURING CO., LTD., trade name "EXM-1201") using a high-pressure mercury lamp as a light source, at an exposure dose sufficient to provide 14 remaining steps after development on a 41-step exposure meter.

[0186] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and a 1% by mass sodium carbonate aqueous solution at 30°C was sprayed for twice the minimum development time (the shortest time to remove the unexposed portion) to remove the unexposed portion. Thus, a resist pattern (dot pattern) was formed. Afterwards, the formed through-hole pattern (through-hole pattern) was observed and evaluated with an optical microscope. In the through-hole pattern arranged in a lattice, in the pattern in which the entire surface was completely removed (opened), the resolution (through-hole pattern) was evaluated by the value of the minimum through-hole pattern diameter. The smaller the numerical value, the better the resolution. In addition, the ratio of the thickness of the resist pattern to the resolution (thickness of the resist pattern / resolution, hereinafter also referred to as "aspect ratio of the through-hole") was calculated. The results are shown in Tables 3 and 4.

[0187] (peelability)

[0188] A glass chrome plate exposure tool (having a 45 mm x 60 mm flat pattern) was placed on the support of the laminate as a negative mask for peel test evaluation. Next, exposure was performed using a parallel light exposure apparatus (manufactured by ORC MANUFACTURING CO., LTD., trade name "EXM-1201") using a high-pressure mercury lamp as a light source, at an exposure dose sufficient to provide 14 remaining steps on a Hitachi 41-step step meter.

[0189] After exposure, the support was peeled off from the laminate to expose the photosensitive layer, and the unexposed portion was removed by spraying a 1% by mass sodium carbonate aqueous solution at 30°C for twice the minimum development time, thereby obtaining a substrate having a cured film. After the substrate was left at room temperature for 3 hours, it was immersed in an amine stripping solution (6% by volume R-100S + 2% by volume R-101 aqueous solution, manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC.) heated to 50°C and stirred at a speed of 400 rpm. The time from the start of stirring to the complete removal of the cured film from the substrate was set to the stripping time (unit: second). The shorter the stripping time, the better the stripping property. The results are shown in Tables 3 and 4.

[0190] [Table 3]

[0191] Example 1 Comparative Example 1 Comparative Example 2 Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 A-1 57.0 - 57.0 57.0 - 57.0 - 57.0 A-2 - 57.0 - - 57.0 - 57.0 - EAB 0.005 0.005 0.083 0.005 0.005 0.083 0.083 0.083 Thickness of photosensitive layer (μm) 80 80 80 40 40 40 7 7 Development (seconds) 47 67 48 23 31 24 7 7 Adhesion (μm) 22 22 ＞50 8 8 25 3 3 Aspect ratio of the resist pattern 3.6 3.6 - 5.0 5.0 1.6 2.3 2.3 Resolution (μm) 20 20 40 12 12 30 5 5 Aspect ratio of vias 4.0 4.0 2.0 3.3 3.3 1.3 1.4 1.4 Peelability (seconds) 263 364 270 71 101 75 14 14

[0192] [Table 4]

[0193] Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 7 A-1 - - 57.0 57.0 57.0 - A-3 57.0 - - - - - A-4 - 57.0 - - - - A-5 - - - - - 57.0 EAB 0.005 0.005 0.001 0.009 - 0.005 Pyrazoline - - - - 0.005 - Thickness of photosensitive layer (μm) 40 40 40 40 40 40 Development (seconds) 19 20 23 23 23 - Adhesion (μm) 18 18 8 9 8 - Aspect ratio of the resist pattern 2.2 2.2 5.0 4.4 5.0 - Resolution (μm) 10 10 14 11 12 - Aspect ratio of vias 4.0 4.0 2.9 3.6 3.3 - Peelability (seconds) 65 62 70 71 72 -

[0194] In Comparative Example 7, since the hydrophobicity and glass transition temperature of the binder polymer were too high, development and peeling could not be performed.

[0195] Explanation of symbols

[0196] 1- photosensitive element, 2- support, 3- photosensitive layer, 4- protective layer.

Claims

1. A photosensitive resin composition comprising: Binder polymer, photopolymerizable compound, photopolymerization initiator and sensitizer, The binder polymer has a structural unit derived from acrylic acid, The content of the sensitizer is less than 0.01 parts by mass based on 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

2. The photosensitive resin composition according to claim 1, wherein The content of the sensitizer is 0.65 parts by mass or less relative to 100 parts by mass of the total amount of the photopolymerization initiator.

3. The photosensitive resin composition according to claim 1, wherein The content of the sensitizer is 0.001 parts by mass or more relative to 100 parts by mass of the total amount of the binder polymer and the photopolymerizable compound.

4. The photosensitive resin composition according to claim 1, wherein The binder polymer further includes at least one selected from the group consisting of a structural unit derived from styrene or a styrene derivative and a structural unit derived from a (meth)acrylate compound having an alicyclic structure.

5. The photosensitive resin composition according to claim 1, wherein The sensitizer includes at least one selected from the group consisting of dialkylaminobenzophenone compounds, pyrazoline compounds, and anthracene compounds. 6 . A photosensitive element comprising a support and a photosensitive layer formed on the support using the photosensitive resin composition according to claim 1 .

7. The photosensitive element according to claim 6, wherein The thickness of the photosensitive layer is greater than 30 μm.

8. A method for forming a resist pattern, comprising: A step of forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of claims 1 to 5; irradiating at least a portion of the photosensitive layer with active light to form a photocured portion; and a step of removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

9. A method for forming a resist pattern, comprising: a step of forming a photosensitive layer on a substrate using the photosensitive element according to claim 6; irradiating at least a portion of the photosensitive layer with active light to form a photocured portion; and a step of removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern. 10 . A method for producing a printed wiring board, comprising the step of forming a conductor pattern by etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method according to claim 8 . 11 . A method for producing a printed wiring board, comprising the step of forming a conductor pattern by etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method according to claim 9 .

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