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

Abstract

A photosensitive element according to the present disclosure comprises a support, and a photosensitive layer formed on the support by using a photosensitive resin composition, wherein: the photosensitive layer has a thickness of 10 μm or less; the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer; the binder polymer has a first structural unit derived from acrylic acid; and the binder polymer has an acid value of 140-165 mgKOH / g.

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 resin compositions and photosensitive elements comprising a layer formed on a support film using the photosensitive resin composition (hereinafter also referred to as a "photosensitive layer") are widely used as resist materials used in etching processes, plating processes, and the like (see, for example, Patent Document 1).

[0003] A printed wiring board is manufactured using the photosensitive element, for example, by the following procedure. That is, first, the photosensitive layer of the photosensitive element is laminated onto a circuit-forming substrate such as a copper-clad laminate. Next, the photosensitive layer is exposed to light through a mask film or the like to form a photocured portion. At this time, the support film is peeled off before or after exposure. Thereafter, the area of ​​the photosensitive layer other than the photocured portion is removed with a developer to form a resist pattern. Next, using the resist pattern as a resist, an etching process or a plating process is performed to form a conductor pattern, and finally, the photocured portion of the photosensitive layer (resist pattern) is peeled off (removed).

[0004] JP 2013-195712 A

[0005] With the recent trend toward smaller and more powerful devices and modules, the formation of high-density, fine wiring is required for semiconductor packages. Accordingly, it is desired that photosensitive resin compositions be used to form finer resist patterns with line widths and space widths of 5 μm or less, and even with line widths and space widths of 2 μm or less. In order to form finer resist patterns, further improvements in the developability and resolution of the photosensitive layer are required.

[0006] An object of the present disclosure is to provide a photosensitive element that has excellent developability and resolution and is capable of forming a finer resist pattern, 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 including a support and a photosensitive layer formed on the support using a photosensitive resin composition, the photosensitive layer having a thickness of 10 μm or less, the photosensitive layer containing a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, the binder polymer having a first structural unit derived from acrylic acid, and an acid value of the binder polymer of 140 to 165 mgKOH / g. [2] The photosensitive element according to [1] above, wherein the acid value of the binder polymer is 145 to 160 mgKOH / g. [3] A photosensitive element comprising a support and a photosensitive layer formed on the support using a photosensitive resin composition, wherein the photosensitive layer has a thickness of 10 μm or less, and the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer, the binder polymer having a first structural unit derived from acrylic acid and a second structural unit derived from styrene or a styrene derivative, the content of the first structural unit being 18.0 to 22.0 mass% and the content of the second structural unit being 60.0 mass% or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer. [4] The photosensitive element according to [3] above, wherein the binder polymer further has a third structural unit derived from a (meth)acrylate compound having an alicyclic structure. [5] The photosensitive element according to any one of [1] to [4] above, wherein the binder polymer has a weight-average molecular weight of 30,000 to 48,000. [6] The photosensitive element according to any one of [1] to [5] above, wherein the photosensitive layer further contains an ultraviolet absorber. [7] A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to any one of [1] to [6] above; irradiating at least a portion of the photosensitive layer with actinic rays to form a photocured portion; and removing the unphotocured portion of the photosensitive layer from the substrate to form a resist pattern. [8] A method for producing a 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 [7] above, to form a conductor pattern.[9] The method for producing a printed wiring board according to [8] above, further comprising a step of removing the resist pattern after the etching treatment or plating treatment.

[0008] According to the present disclosure, it is possible to provide a photosensitive element that has excellent developability and resolution and is capable of forming a finer resist pattern, a method for forming a resist pattern, and a method for producing a printed wiring board.

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

[0010] In this specification, the term "process" includes not only an independent process but also 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 of this embodiment includes a support and a photosensitive layer formed on the support. When using the photosensitive element of this embodiment, after laminating the photosensitive layer on a substrate, exposure may be performed without peeling off the support (support film).

[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, a photosensitive layer 3 formed on the support 2, and other layers such as a protective layer 4 that may be provided as needed. Each layer in the photosensitive element according to this embodiment will be described in detail below.

[0015] The support 2 and the protective layer 4 may each be a polymer film having heat resistance and solvent resistance, for example, a polyester film such as a polyethylene terephthalate film, a polyethylene film, a polyolefin film such as a polypropylene film, etc. The support 2 and the protective layer 4 may each be a film of a hydrocarbon polymer other than polyolefin. A film of a hydrocarbon polymer including polyolefin may have a low density, for example, a density of 1.014 g / cm ３ The support 2 and the protective layer 4 may each be a stretched film obtained by stretching the low-density hydrocarbon-based polymer film. The type of polymer film constituting the protective layer 4 may be the same as or different from the type of polymer film constituting the support 2.

[0016] These polymer films are commercially available as polyethylene terephthalate films such as the PS series (e.g., PS-25) manufactured by Teijin Limited, polyethylene films such as NF-15 manufactured by Tamapoly Co., Ltd., or polypropylene films manufactured by Oji Paper Co., Ltd. (e.g., Alphan MA-410, E-200C) and Shin-Etsu Film Co., Ltd.

[0017] The thickness of the support 2 may be 1 μm or more or 5 μm or more from the viewpoint of preventing damage to the support 2 when peeling the support 2 from the photosensitive layer 3, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of enabling suitable exposure even when exposure is performed through the support 2.

[0018] The thickness of the protective layer 4 may be 1 μm or more, 5 μm or more, or 15 μm or more from the viewpoint of suppressing damage to the protective layer 4 when the photosensitive layer 3 and the support 2 are laminated onto the substrate while peeling off the protective layer 4, and may be 100 μm or less, 50 μm or less, or 30 μm or less from the viewpoint of improving productivity.

[0019] From the viewpoint of forming a fine resist pattern, the thickness of the photosensitive layer 3 is 10 μm or less. The thickness of the photosensitive layer 3 after drying (after volatilizing the organic solvent when the photosensitive resin composition contains an organic solvent) may be 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more from the viewpoint of facilitating coating and improving productivity, and may be 9 μm or less, 8 μm or less, or 7 μm or less from the viewpoint of further improving resolution.

[0020] The photosensitive layer 3 is a layer formed using a photosensitive resin composition described below, and contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator, and a sensitizer. The photosensitive layer 3 may contain a polymerization inhibitor, an ultraviolet absorber, or other components as needed. Each component used in the photosensitive resin composition of this embodiment will be described in more detail below.

[0021] (Component (A): Binder Polymer) The photosensitive resin composition according to this embodiment contains a binder polymer having a specific structure as component (A), which can improve the developability and resolution of a photosensitive layer formed from the photosensitive resin composition.

[0022] The binder polymer according to this embodiment may have a first structural unit derived from acrylic acid, and the acid value of the binder polymer may be 140 to 165 mgKOH / g. The binder polymer according to this embodiment may have a first structural unit derived from acrylic acid and a second structural unit derived from styrene or a styrene derivative, and the content of the first structural unit may be 18.0 to 22.0 mass% and the content of the second structural unit may be 60.0 mass% or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer.

[0023] The component (A) can be produced by radical polymerization of a polymerizable monomer containing acrylic acid. When the component (A) has a first structural unit derived from acrylic acid, the alkali developability of the photosensitive resin composition can be improved.

[0024] The content of the first structural unit in the component (A) may be 18.0% by mass or more, 18.5% by mass or more, 19.0% by mass or more, or 19.5% by mass or more, based on the total mass (100% by mass) of the structural units derived from the polymerizable monomers constituting the binder polymer, from the viewpoint of further shortening the development time. From the viewpoint of further improving resolution, the content of the first structural unit may be 22.0% by mass or less, 21.5% by mass or less, or 21.0% by mass or less. From the viewpoint of improving developability and resolution in a balanced manner, the content of the first structural unit may be 18.0 to 22.0% by mass, 18.5 to 22.0% by mass, 19.0 to 21.5% by mass, or 19.5 to 21.0% by mass.

[0025] The component (A) having a second structural unit derived from styrene or a styrene derivative, such as vinyl toluene, α-methyl styrene, p-methyl styrene, and p-ethyl styrene, can improve the resolution and adhesion of the photosensitive resin composition.

[0026] The content of the second structural unit in component (A) may be 60.0% by mass or more, 64.0% by mass or more, 68.0% by mass or more, or 70.0% by mass or more, based on the total mass of the structural units derived from the polymerizable monomers constituting the binder interpolymer, from the viewpoint of further improving adhesion. The content of the second structural unit may be 85.0% by mass or less, 84.0% by mass or less, 83.0% by mass or less, or 80% by mass or less, from the viewpoint of further shortening the peeling time. From the viewpoint of improving adhesion and peeling in a balanced manner, the content of the styrene-based structural unit may be 60.0 to 85.0% by mass, 64.0 to 84.0% by mass, 68.0 to 83.0% by mass, or 70.0 to 80.0% by mass.

[0027] When the component (A) has a third structural unit derived from a (meth)acrylate compound having an alicyclic structure, the balance between the developability and the resolution of the photosensitive resin composition can be adjusted.

[0028] Examples of the (meth)acrylate having an alicyclic structure include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclopentanyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0029] The content of the third structural unit may be 0.5 mass% or more, 1.0 mass% or more, 2.0 mass% or more, or 3.0 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 of the photosensitive resin composition, and may be 18.0 mass% or less, 15.0 mass% or less, 10.0 mass% or less, or 8.0 mass% or less, from the viewpoint of further improving the developability of the photosensitive resin composition.

[0030] Component (A) may further contain structural units derived from polymerizable monomers other than those described above (hereinafter also referred to as "other monomers"). Examples of other monomers include methacrylic acid, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, benzyl (meth)acrylate or derivatives thereof, 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-furyl (meth)acrylic acid, β-styryl (meth)acrylic acid, maleic acid, maleic anhydride, maleic acid monoalkyl ester, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. These may be used alone or in combination of two or more.

[0031] The weight average molecular weight (Mw) of component (A) may be 25,000 to 50,000, 30,000 to 48,000, 32,000 to 46,000, or 35,000 to 44,000. When Mw is 50,000 or less, resolution and developability tend to be further improved, while when Mw is 25,000 or more, chipping and peeling of the resist pattern tend to be less likely to occur. The dispersity (Mw / Mn) of component (A) may be 1.0 to 3.0, 1.0 to 2.5, or 1.0 to 2.3. As the dispersity decreases, resolution tends to improve.

[0032] Mw and Mn can be measured, for example, by gel permeation chromatography (GPC) using a calibration curve of standard polystyrene. More specifically, they can be measured under the conditions described in the Examples.

[0033] From the viewpoint of achieving both developability and strippability, the acid value of component (A) may be 140 to 165 mgKOH / g, 144 to 163 mgKOH / g, 145 to 160 mgKOH / g, or 146 to 158 mgKOH / g. When the acid value of component (A) is 140 mgKOH / g or more, development time can be more easily shortened, and when it is 165 mgKOH / g or less, resolution is further improved, making it easier to form a finer resist pattern. 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 in accordance with JIS K6901:2008 5.3.2.

[0034] From the viewpoint of resolution or adhesion, the glass transition temperature (Tg) of the component (A) may be 70 to 125° C., 90 to 120° C., 94 to 110° C., or 96 to 108° C. The Tg of the component (A) is a value determined according to the Fox equation, and can be calculated from the mass of each polymerizable monomer constituting the component (A) and the Tg of a homopolymer of each polymerizable monomer.

[0035] The content of the (A) component 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, relative to 100 parts by mass of the total amount of the (A) component and the (B) component, 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.

[0036] (Component (B): Photopolymerizable Compound) The component (B) is not particularly limited as long as it has at least one ethylenically unsaturated bond and is a photopolymerizable compound. From the viewpoint of improving alkali developability, resolution, and release properties after curing, the component (B) preferably contains at least one bisphenol (meth)acrylate, and among bisphenol (meth)acrylates, it is more preferable to contain bisphenol A (meth)acrylate.

[0037] Examples of bisphenol A type (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. Of these, 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is preferred from the viewpoint of further improving resolution and release properties.

[0038] 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%, 60 to 95 mass%, or 70 to 90 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. In particular, from the viewpoint of achieving a balanced improvement in resolution, adhesion, resist shape, and post-curing release properties, component (B) may contain at least one compound selected from nonylphenoxy polyethyleneoxy acrylate and a phthalic acid compound. However, because the refractive index of these compounds is relatively low, from the viewpoint of improving resolution, the content thereof may be 5 to 50 mass%, 5 to 40 mass%, or 10 to 30 mass%, based on the total amount of component (B).

[0045] Examples of nonylphenoxy polyethyleneoxyacrylates include nonylphenoxytriethyleneoxyacrylate, nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate, nonylphenoxynonaethyleneoxyacrylate, nonylphenoxydecaethyleneoxyacrylate, and nonylphenoxyundecaethyleneoxyacrylate.

[0046] Examples of phthalic acid compounds include γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β'-(meth)acryloyloxyethyl-o-phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate. γ-Chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate is commercially available as FA-MECH (trade name, manufactured by Resonac Corporation).

[0047] From the viewpoint of improving sensitivity and reducing tailing, the component (B) may contain a (meth)acrylic acid polyol ester. Examples of the (meth)acrylic acid polyol ester include trimethylolpropane polyethoxy tri(meth)acrylate, trimethylolpropane polypropoxy tri(meth)acrylate, trimethylolpropane polybutoxy tri(meth)acrylate, trimethylolpropane polyethoxy polypropoxy tri(meth)acrylate, trimethylolethane polyethoxy tri(meth)acrylate, trimethylolethane polypropoxy tri(meth)acrylate, trimethylolethane polybutoxy tri(meth)acrylate, and trimethylolethane polyethoxy tri(meth)acrylate. Examples of the glyceryl polyacrylate include glyceryl polypropoxytri(meth)acrylate, pentaerythritol polyethoxytri(meth)acrylate, pentaerythritol polypropoxytri(meth)acrylate, pentaerythritol polybutoxytri(meth)acrylate, pentaerythritol polyethoxypolypropoxytri(meth)acrylate, glyceryl polyethoxytri(meth)acrylate, glyceryl polypropoxytri(meth)acrylate, glyceryl polybutoxytri(meth)acrylate, and glyceryl polyethoxypolypropoxytri(meth)acrylate.

[0048] The content of component (B) is preferably 20 to 60 parts by mass, more preferably 30 to 55 parts by mass, and even more preferably 35 to 50 parts by mass, relative to 100 parts by mass of the total amount of components (A) and (B). When the content of component (B) is within this range, the photosensitive resin composition exhibits improved photosensitivity and film properties in addition to improved resolution and adhesion.

[0049] (Component (C): Photopolymerization Initiator) 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.

[0050] Examples of the component (C) include hexaarylbiimidazole compounds; aromatic ketone compounds such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propanone-1; alkyl aryl ketone compounds such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone; benzoin ether compounds such as benzoin alkyl ether; benzoin compounds such as benzoin and alkylbenzoin; benzyl derivatives such as benzyl dimethyl ketal; and phosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethylbenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0051] Component (C) may contain a hexaarylbiimidazole compound from the viewpoint of improving the adhesion of the photosensitive layer to a smooth substrate. The aryl group in the hexaarylbiimidazole compound may be a phenyl group or the like. A hydrogen atom bonded to the aryl group in the hexaarylbiimidazole compound may be substituted with a halogen atom (e.g., a chlorine atom).

[0052] 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.

[0053] The content of component (C) may be 1.0 to 10 parts by mass, 2.0 to 8.0 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 components (A) and (B). When the content of component (C) is within this range, it becomes easy to improve both photosensitivity and resolution in a balanced manner.

[0054] (Component (D): Sensitizer) The photosensitive resin composition according to this embodiment contains the component (D), which allows effective use of the absorption wavelength of actinic rays used for exposure.

[0055] Examples of component (D) include dialkylaminobenzophenone compounds, pyrazoline compounds, anthracene compounds, coumarin compounds, xanthone compounds, thioxanthone compounds, oxazole compounds, benzoxazole compounds, thiazole compounds, benzothiazole compounds, triazole compounds, stilbene compounds, triazine compounds, thiophene compounds, naphthalimide compounds, triarylamine compounds, and aminoacridine compounds. From the viewpoint of further improving resolution and adhesion, component (D) may contain a pyrazoline compound or a dialkylaminobenzophenone compound.

[0056] Examples of the 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, 1,5-bis-(4-isopropylphenyl)-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-isopropyl-styryl)-5-(4-isopropyl 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, 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-(3,4-dimethoxystyryl)-5- (3,4-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.

[0057] Examples of dialkylaminobenzophenone compounds include 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide.

[0058] From the viewpoint of further improving adhesion, the content of the component (D) may be 1.60 parts by mass or less, 1.50 parts by mass or less, 1.40 parts by mass or less, or 1.35 parts by mass or less, relative to 100 parts by mass of the component (C). From the viewpoint of improving developability, adhesion, and releasability in a balanced manner, the content of the component (D) may be 0.15 to 1.60 parts by mass, 0.20 to 1.50 parts by mass, 0.25 to 1.40 parts by mass, or 0.30 to 1.35 parts by mass, relative to 100 parts by mass of the component (C).

[0059] From the viewpoint of improving photosensitivity and resolution, the content of the component (D) may be 0.01 to 0.10 parts by mass, 0.01 to 0.09 parts by mass, or 0.01 to 0.08 parts by mass, relative to 100 parts by mass of the total amount of the component (A) and the component (B).

[0060] (Component (E): Polymerization Inhibitor) The 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 4-tert-butylcatechol and 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl.

[0061] 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, per 100 parts by mass of the total amount of the components (A) and (B).

[0062] (Component (F): Ultraviolet Absorber) From the viewpoint of forming a finer resist pattern, the photosensitive resin composition may contain an ultraviolet absorber as the component (F).

[0063] Component (F) may be a compound that absorbs light in the range of 340 to 430 nm, or may be a compound that efficiently absorbs light with a wavelength of 365 nm. The molar absorption coefficient of component (F) for light with a wavelength of 365 nm is in the range of 500 to 50,000 L / (mol cm). The molar absorption coefficient is an index of the ease of light absorption.

[0064] When the photosensitive layer is exposed to actinic rays of 340 to 430 nm, component (F) may contain at least one compound selected from the group consisting of benzophenone compounds, benzotriazole compounds, and triazine compounds, since it effectively absorbs light of the exposure wavelength. The benzophenone compound may be a benzophenone compound in which some of the hydrogen atoms are substituted with groups having oxygen atoms, or a benzophenone compound having a hydroxy group.

[0065] Examples of benzophenone compounds include 4,4'-dimethoxybenzophenone, 4,4'-bis(trimethylacetoxy)benzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-(octyloxy)benzophenone, and 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid. Examples of benzotriazole compounds include 2,2-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol], 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, and 2-(5-chloro-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol. Examples of triazine compounds include 2-[4,6-di(2,4-xylyl)-1,3,5-triazin-2-yl]-5-octyloxyphenol, and 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine.

[0066] The content of the component (F) may be 0.05 to 5.0 parts by mass, 0.1 to 4.0 parts by mass, or 0.2 to 2.0 parts by mass, per 100 parts by mass of the total amount of the components (A) and (B).

[0067] (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).

[0068] The photosensitive resin composition may contain an organic solvent to improve the handleability of the photosensitive composition and to adjust the viscosity and storage stability. Any commonly used organic solvent can be used as the organic solvent without any particular 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. These may be used alone or in combination of two or more.

[0069] The photosensitive element 1 can be obtained, for example, as follows. First, a photosensitive layer 3 is formed on a support 2. The photosensitive layer 3 can be formed, for example, by applying a photosensitive resin composition containing an organic solvent to form a coating layer and drying the coating layer. Next, a protective layer 4 is formed on the surface of the photosensitive layer 3 opposite the support 2.

[0070] The coating layer is formed by a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating, etc. The coating layer is dried so that the amount of organic solvent remaining in the photosensitive layer 3 is, for example, 2% by mass or less, and specifically, for example, at 70 to 150°C for about 5 to 30 minutes.

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

[0072] In another embodiment, the photosensitive element may not include a protective layer, and may further include other layers such as a cushion layer, an adhesive layer, a light-absorbing layer, and a gas barrier layer.

[0073] The photosensitive element 1 may be, for example, in the form of a sheet, or may be in the form of a photosensitive element roll wound around a core. In the photosensitive element roll, the photosensitive element 1 is preferably wound with the support 2 facing outward. The core is formed of, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, or the like. An end separator may be provided on the end face of the photosensitive element roll from the viewpoint of end face protection, and a moisture-proof end face separator may be provided from the viewpoint of edge fusion resistance. The photosensitive element 1 may be wrapped, for example, in a black sheet with low moisture permeability.

[0074] The photosensitive element 1 can be suitably used for forming a resist pattern, and can be particularly suitably used in the method for producing a printed wiring board, which will be described later.

[0075] [Method 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.

[0076] (Photosensitive layer forming process) As a method for forming a photosensitive layer on a substrate, 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.

[0077] The photosensitive layer forming step is preferably carried out under reduced pressure from the viewpoint of adhesion and followability. The photosensitive layer and / or the substrate may be heated at a temperature of 70 to 130°C during pressure bonding. The pressure is 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.

[0078] (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.

[0079] Examples of the exposure method include a method of irradiating an actinic ray imagewise through a negative or positive mask pattern called artwork (mask exposure method). Alternatively, a method of irradiating an actinic ray imagewise by a projection exposure method may be employed. Alternatively, a method of irradiating an actinic ray imagewise by a direct writing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be employed.

[0080] 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.

[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 improving resolution, a high-pressure spray method may be used as the development method. Development may also be carried out by combining two or more of these methods.

[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 the present 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 invention is not limited to these examples.

[0096] (Component (A): Binder Polymer) Acrylic acid (AA), methacrylic acid (MAA), styrene (ST), and dicyclopentanyl methacrylate (TCDMA) were prepared as polymerizable monomers, and solutions of binder polymers (A-1) to (A-7) shown in Table 1 were prepared by the following procedure.

[0097] (A-1) 91.3 g of acrylic acid (AA), 314.5 g of styrene (ST), and 9.4 g of dicyclopentanyl methacrylate (TCDMA) (AA / ST / TCDMA mass ratio = 21.0 / 72.2 / 6.8) were mixed with 4.6 g of tert-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name "Perbutyl (registered trademark) O") as a thermal radical polymerization initiator, and 128.6 g of propylene glycol monomethyl ether as a solvent to prepare a mixture (x). 4.4 g of Perbutyl O was dissolved in 37.4 g of propylene glycol monomethyl ether to prepare a solution (a).

[0098] A flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer, and a gas inlet tube was charged with 46.2 g of propylene glycol monomethyl ether and 174.8 g of toluene, and the mixture was stirred under a nitrogen atmosphere while replacing the gas, and the temperature was raised to 98°C. Next, mixture (x) was added dropwise to the flask over 2 hours. After the dropwise addition was completed, the mixture was stirred at 98°C for 2 hours, and then solution (a) was added and stirred for an additional 3 hours. Next, with continued stirring, the solution in the flask was heated to 105°C over 20 minutes, and then stirred at 105°C for 2 hours. Next, 93.8 g of propylene glycol monomethyl ether and 74.2 g of toluene were added, and the mixture was cooled to room temperature with stirring to obtain a solution of binder polymer (A-1).

[0099] (A-2) to (A-7) Solutions of binder polymers (A-2) to (A-7) were obtained in the same manner as for obtaining the solution of binder polymer (A-1), except that mixture (x) was prepared using the polymerizable monomers shown in Table 1 in the mass ratios shown in the same table.

[0100] (Weight-average molecular weight) A binder polymer solution was dissolved in tetrahydrofuran (THF) to prepare a 0.2% by mass THF solution as a sample for Mw measurement. Mw was measured by gel permeation chromatography (GPC) and calculated by conversion using a calibration curve of standard polystyrene. The GPC conditions are as follows: Measuring apparatus: Shodex GPC-101 (manufactured by Resonac Co., Ltd.) Detector: Differential refractometer Shodex RI-71S (manufactured by Resonac Co., Ltd.) Column: Shodex LF-804 + LF-804 (manufactured by Resonac Co., Ltd.) Column temperature: 40°C Eluent: tetrahydrofuran (THF) Flow rate: 1 mL / min

[0101] (Acid Value) The acid value of the binder polymer was measured by neutralization titration in accordance with JIS K6901:2008 5.3.2.

[0102]

[0103] [Photosensitive Resin Composition] Photosensitive resin compositions of the Examples and Comparative Examples were prepared by mixing each component in the blending amounts (parts by mass) shown in Table 2 with respect to a binder polymer solution having a solid content of 57 parts by mass. Details of each component shown in Table 2 are as follows.

[0104] (Component (B): Photopolymerizable Compound) FA-321M: 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (manufactured by Resonac Corporation, number of EO groups: 10 (average)) FA-024M: PO-EO-PO modified dimethacrylate (manufactured by Resonac Corporation, number of EO groups: 6 (average), number of PO groups: 12 (average)) BP-2EM: Ethoxylated bisphenol A dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., number of EO groups: 2.6 (average)) (Component (C): Photopolymerization Initiator) B-CIM: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Hodogaya Chemical Co., Ltd.) (Component (D): Sensitizer) PZ-501D: 1-phenyl-3-(4-methoxystyryl)-5-(4-methoxyphenyl)pyrazoline (manufactured by Nippon Chemical Industry Co., Ltd.) (Component (E): polymerization inhibitor) 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) (Component (F): ultraviolet absorber) SEESORB-106: 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (Shipro Chemical Co., Ltd.) (adhesion promoter) SF-808H: mixture of carboxybenzotriazole, 5-amino-1H-tetrazole and methoxypropanol (manufactured by Sanwa Chemical Co., Ltd.) (photocolor former) LCV: Leuco Crystal Violet (manufactured by Yamada Chemical Co., Ltd.) (dye) MKG: Malachite Green (Osaka Organic Chemical Industry Ltd.)

[0105]

[0106] [Photosensitive element] A 16 μm thick polyethylene terephthalate film (manufactured by Toray Industries, Inc., product name "FS-31") was prepared as a support. The photosensitive resin composition was applied to the support and then dried for 10 minutes in a hot air convection dryer at 90°C to form a photosensitive layer having the thickness shown in Table 3. Subsequently, a polyethylene film (manufactured by Tamapoly Corporation, product name "NF-15A") was laminated as a protective layer on the photosensitive layer to obtain a photosensitive element in which the support, photosensitive layer, and protective layer were laminated in this order.

[0107] [Laminate] A substrate formed by copper sputtering on a silicon wafer 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 the photosensitive layer of the photosensitive element in contact with the copper surface of the copper substrate, while peeling off the protective layer, at a pressure of 0.4 MPa and a roll speed of 1.0 m / min. This resulted in a laminate in which the substrate, photosensitive layer, and support were laminated in this order. The resulting laminate was used as a test piece for the following tests.

[0108] (Minimum Development Time) The support was peeled off from the test piece to expose the photosensitive layer, and a 1% by mass aqueous solution of sodium carbonate was sprayed at 30° C. The time until the photosensitive layer was completely removed was measured and defined as the minimum development time.

[0109] (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 projection exposure apparatus (manufactured by Ushio Inc., product name "UX-44101SM") using an ultra-high pressure mercury lamp (365 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 ２ The sensitivity (photosensitivity) was evaluated by the following formula: The lower the exposure amount, the higher the sensitivity.

[0110] (Resolution) A glass chrome type phototool (resolution negative: having a wiring pattern of line width / space width of x / x (x: 1 to 10, unit: μm)) was used as a negative for evaluating resolution on the support of a test piece, and the photosensitive layer was exposed to a predetermined energy amount using a projection exposure apparatus (Canon Inc., product name "FPA-3000iW") using an ultra-high pressure mercury lamp (365 nm) as a light source. After exposure, the support was peeled off to expose the photosensitive layer, and a 1 mass % sodium carbonate aqueous solution at 30°C was sprayed on it for a time twice the minimum developing time to remove the unexposed portion (development treatment).

[0111] After development, the space portions (unexposed portions) were completely removed, and the line portions (exposed portions) were formed without distortion, meandering, or chipping. The resolution was evaluated based on the smallest line width / space width ratio among the resist patterns. The smaller this value, the better the resolution.

[0112]

[0113] As is clear from Table 3, the photosensitive elements of Examples 1 to 5 had improved developability and resolution, and were able to form fine resist patterns. On the other hand, the photosensitive element of Comparative Example 1 did not have sufficient resolution, and the photosensitive elements of Comparative Examples 2 to 4 required a long time for development, and were unable to form fine resist patterns.

[0114] 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 using a photosensitive resin composition, wherein the photosensitive layer has a thickness of 10 μm or less, the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator and a sensitizer, the binder polymer has a first structural unit derived from acrylic acid, and the acid value of the binder polymer is 140 to 165 mg KOH / g.

2. The photosensitive element of claim 1, wherein the binder polymer has an acid value of 145 to 160 mg KOH / g.

3. A photosensitive element comprising a support and a photosensitive layer formed on the support using a photosensitive resin composition, wherein the photosensitive layer has a thickness of 10 μm or less, the photosensitive layer contains a binder polymer, a photopolymerizable compound, a photopolymerization initiator and a sensitizer, the binder polymer has a first structural unit derived from acrylic acid and a second structural unit derived from styrene or a styrene derivative, and the content of the first structural unit is 18.0 to 22.0 mass% and the content of the second structural unit is 60.0 mass% or more based on the total mass of the structural units derived from the polymerizable monomers constituting the binder polymer.

4. The photosensitive element according to claim 3, wherein the binder polymer further comprises a third structural unit derived from a (meth)acrylate compound having an alicyclic structure.

5. The photosensitive element according to any one of claims 1 to 4, wherein the binder polymer has a weight average molecular weight of 30,000 to 48,000.

6. The photosensitive element of any one of claims 1 to 5, wherein the photosensitive layer further comprises an ultraviolet light absorber.

7. A method for forming a resist pattern, comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive element according to any one of claims 1 to 6; irradiating at least a portion of the photosensitive layer with active light rays to form a photocured portion; and removing an unphotocured portion of the photosensitive layer from the substrate to form a resist pattern.

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

9. The method for producing a printed wiring board according to claim 8, further comprising the step of removing the resist pattern after the etching or plating process.

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