Photosensitive resin composition

Abstract

To provide a photosensitive resin composition that can reduce the deviation of the obtained resist line width from the design value when forming a resist pattern. [Solution] A photosensitive resin composition comprising (A) a binder polymer, (B) a photopolymerizable compound having at least one ethylenically unsaturated bond, and (C) a photopolymerization initiator, wherein (C) the photopolymerization initiator includes an oxime ester-based photopolymerization initiator, and the content of the oxime ester-based photopolymerization initiator is 0.3 parts by mass or more per 100 parts by mass of the total of (A) the binder polymer and (B) the photopolymerizable compound.

Description

Technical Field

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

Background Art

[0002] In the field of manufacturing printed wiring boards, a photosensitive element including a layer formed on a support (hereinafter referred to as "photosensitive resin layer") using a photosensitive resin composition as a resist material used in etching treatment, plating treatment, etc. is widely used.

[0003] Conventionally, a printed wiring board has been manufactured, for example, by the following procedure using the above photosensitive element. That is, first, the photosensitive resin layer of the photosensitive element is laminated on a circuit formation substrate (copper-clad laminate, etc.). At this time, the lamination is performed so that the photosensitive resin layer adheres to the surface for forming the conductor pattern (circuit) of the circuit formation substrate. Also, the lamination is performed by heat-pressure bonding the photosensitive resin layer to the underlying circuit formation substrate (atmospheric pressure lamination method).

[0004] Next, a desired region of the photosensitive resin layer is exposed through a mask film or the like (mask exposure method). At this time, the support (support film, etc.) is peeled off at either timing before or after the exposure. Then, the unexposed portion of the photosensitive resin layer is dissolved or dispersed and removed with a developer to form a resist pattern composed of the cured portion of the photosensitive resin layer. Next, after performing an etching treatment or a plating treatment to form a conductor pattern, the resist pattern is finally peeled off and removed.

[0005] By the way, as the above-described pattern exposure method, recently, a direct drawing method (such as an LDI (Lazer Direct Imaging) method) that directly draws circuit data created by CAD with laser light without requiring a mask film is becoming widespread.

[0006] Direct lithography (LDI) methods offer many advantages, including reduced mask film costs due to the elimination of mask film, high accuracy in aligning resist openings, easy scaling correction, and elimination of the need to manage foreign matter, dirt, and scratches on the mask.

[0007] As a photosensitive resin composition that can be used in such a direct drawing method, for example, a photosensitive resin composition containing a specific binder polymer and a specific photopolymerization initiator has been proposed (see, for example, Patent Documents 1 and 2 below). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2010-217400 [Patent Document 2] International Publication No. 2012 / 014580 [Patent Document 3] Japanese Patent Application Publication No. 11-327137 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0009] In both mask exposure and direct writing methods, accurately forming a resist pattern is necessary to create fine wiring. However, when using conventional photosensitive resin compositions to form resist patterns, there was a problem in that the resist line width after exposure and development tended to be thicker than the design value.

[0010] Therefore, the present disclosure aims to provide a photosensitive resin composition that can reduce the deviation of the resist line width obtained from the design value when a resist pattern is formed. Furthermore, the present disclosure aims to provide a photosensitive element, a cured product, a method for forming a resist pattern, and a method for manufacturing a printed circuit board using the above photosensitive resin composition. [Means for solving the problem]

[0011] To solve the above problems, this disclosure provides the following photosensitive resin composition, photosensitive element, cured product, method for forming a resist pattern, and method for manufacturing a printed circuit board.

[0012] [1] A photosensitive resin composition comprising (A) a binder polymer, (B) a photopolymerizable compound having at least one ethylenically unsaturated bond, and (C) a photopolymerization initiator, wherein the (C) photopolymerization initiator includes an oxime ester-based photopolymerization initiator, and the content of the oxime ester-based photopolymerization initiator is 0.3 parts by mass or more with respect to 100 parts by mass of the total of the (A) binder polymer and the (B) photopolymerizable compound. [2] The photosensitive resin composition according to [1] above, wherein the binder polymer (A) has structural units derived from (meth)acrylic acid and structural units derived from benzyl (meth)acrylate or a benzyl (meth)acrylate derivative. [3] The photosensitive resin composition according to [1] or [2] above, wherein the (C) photopolymerization initiator consists solely of the oxime ester-based photopolymerization initiator. [4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the oxime ester-based photopolymerization initiator comprises a compound having a carbazole structure. [5] The photosensitive resin composition according to any one of [1] to [4] above, wherein the oxime ester-based photopolymerization initiator comprises a compound having a phenyl sulfide structure. [6] The photosensitive resin composition according to any one of [1] to [5] above, wherein the oxime ester-based photopolymerization initiator comprises a compound having a fluorene structure. [7] The photosensitive resin composition according to any one of [1] to [6] above, wherein the content of the oxime ester-based photopolymerization initiator is 3.0 parts by mass or less with respect to 100 parts by mass of the total of the binder polymer (A) and the photopolymerizable compound (B). [8] A photosensitive resin composition according to any one of [1] to [7] above, used in a direct drawing method. [9] A photosensitive element comprising a support and a photosensitive resin layer disposed on the support, wherein the photosensitive resin layer contains the photosensitive resin composition described in any of [1] to [8] above or a cured product thereof.

[10] A cured product of any of the photosensitive resin compositions described in [1] to [8] above.

[11] The cured product described in

[10] above, which is a resist pattern.

[12] A method for forming a resist pattern, comprising the steps of: forming a photosensitive resin layer on a substrate using a photosensitive resin composition described in any of [1] to [8] above; curing the photosensitive resin layer by irradiating at least a part of the photosensitive resin layer with an active light; and removing the uncured portion of the photosensitive resin layer from the substrate to form a resist pattern.

[13] A method for forming a resist pattern, comprising the steps of: forming a photosensitive resin layer on a substrate using the photosensitive element described in [9] above; curing the photosensitive resin layer by irradiating at least a part of the photosensitive resin layer with an active light; and removing the uncured portion of the photosensitive resin layer from the substrate to form a resist pattern.

[14] A method for manufacturing a printed circuit board, comprising the steps of forming a resist pattern on the substrate by the resist pattern formation method described in

[12] or

[13] above, and plating or etching the substrate and the member having the resist pattern. [Effects of the Invention]

[0013] According to this disclosure, it is possible to provide a photosensitive resin composition that can reduce the deviation of the resist line width obtained from the design value when a resist pattern is formed. Furthermore, this disclosure can provide a photosensitive element, a cured product, a method for forming a resist pattern, and a method for manufacturing a printed circuit board using the above photosensitive resin composition. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view showing a photosensitive element according to one embodiment of the present disclosure. [Figure 2] It is a perspective view schematically showing an example of a manufacturing process of a printed wiring board by a semi-additive process.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described in detail. It should be understood that other embodiments can be considered and fabricated without departing from the scope and spirit of the present disclosure. Therefore, the description of the following "Mode for Carrying Out the Invention" should not be understood in a limiting sense.

[0016] In this specification, the term "process" includes not only an independent process but also a process in which the intended action of the process is achieved even if it cannot be clearly distinguished from other processes. The numerical range indicated by "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of the numerical range at a certain step may be replaced with the upper limit value or the lower limit value of the numerical range at other steps. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. The term "layer" includes not only a structure formed over the entire surface but also a structure formed partially when observed as a plan view. "(Meth)acrylic acid" means at least one of "acrylic acid" and the corresponding "methacrylic acid". The same applies to other similar expressions such as (meth)acrylate.

[0017] When referring to the amount of each component in the composition in this specification, in the case where there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition. In this specification, "room temperature" refers to 25°C. In this specification, "solid content" refers to the non-volatile content excluding volatile substances (such as water, solvents, etc.) in the photosensitive resin composition. That is, it refers to components other than solvents such as water and organic solvents that remain without volatilizing in the drying process, and also includes substances in a liquid state, a molasses state, and a wax state near room temperature (25°C).

[0018] "(Poly)oxyethylene group" means an oxyethylene group or a polyoxyethylene group in which two or more ethylene groups are linked by an ether bond. "(Poly)oxypropylene group" means an oxypropylene group or a polyoxypropylene group in which two or more propylene groups are linked by an ether bond. "EO modification" means a compound having a (poly)oxyethylene group. "PO modification" means a compound having a (poly)oxypropylene group. "EO·PO modification" means a compound having both a (poly)oxyethylene group and a (poly)oxypropylene group.

[0019] <Photosensitive Resin Composition and Its Cured Product> The photosensitive resin composition according to this embodiment contains (A) a binder polymer (hereinafter also referred to as component (A)), (B) a photopolymerizable compound having at least one ethylenically unsaturated bond (hereinafter also referred to as component (B)), and (C) a photoinitiator (hereinafter also referred to as component (C)). In the photosensitive resin composition according to this embodiment, the above-mentioned (C) photoinitiator includes an oxime ester-based photoinitiator. In the photosensitive resin composition according to this embodiment, the content of the above-mentioned oxime ester-based photoinitiator is 0.3 parts by mass or more with respect to 100 parts by mass in total of the above-mentioned (A) binder polymer and the above-mentioned (B) photopolymerizable compound.

[0020] The photosensitive resin composition according to this embodiment contains an oxime ester-based photopolymerization initiator as component (C) in an amount of 0.3 parts by mass or more per 100 parts by mass of the total of components (A) and (B). This suppresses the formation of a resist pattern using either a mask exposure method or a direct writing method, thereby reducing deviations from the design value of the resist line width. Conventionally, when the deviation of the obtained resist line width from the design value was large, it was necessary to correct the drawing data or mask film to account for the thicker or thinner resist line width. However, by using the photosensitive resin composition according to this embodiment, a resist line width close to the design value can be obtained without correction. Therefore, correction of the design value is not necessary, or only slight correction is required, in the exposure process, making it possible to perform the exposure process efficiently.

[0021] The cured product according to this embodiment is a cured product of the photosensitive resin composition according to this embodiment. The cured product according to this embodiment may also be a resist pattern.

[0022] ((A) Ingredient: Binder polymer) Examples of component (A) that can be used in the photosensitive resin composition according to this embodiment include (meth)acrylic resins (resins having structural units derived from (meth)acrylic acid), styrene resins, epoxy resins, amide resins, amide epoxy resins, alkyd resins, and phenolic resins. From the viewpoint of further improving alkali developability, the photosensitive resin composition according to this embodiment may contain a (meth)acrylic resin, and component (A) may have structural units derived from (meth)acrylic acid. In addition, component (A) may have structural units derived from polymerizable monomers other than (meth)acrylic acid. Examples of such structural units include structural units derived from styrene or styrene derivatives, structural units derived from alkyl (meth)acrylate, structural units derived from benzyl (meth)acrylate or benzyl (meth)acrylate derivatives, etc. From the viewpoint of improving resolution and adhesion, it is preferable that component (A) has at least structural units derived from (meth)acrylic acid and structural units derived from benzyl (meth)acrylate or benzyl (meth)acrylate derivatives. Furthermore, from the viewpoint of further improving resolution and adhesion, component (A) may have structural units derived from hydroxyalkyl (meth)acrylate. Alternatively, component (A) may consist only of at least one structural unit selected from the group consisting of structural units derived from (meth)acrylic acid, structural units derived from styrene or styrene derivatives, structural units derived from alkyl (meth)acrylate, structural units derived from benzyl (meth)acrylate or benzyl (meth)acrylate derivatives, and structural units derived from hydroxyalkyl (meth)acrylate. Component (A) can be produced, for example, by radical polymerization of a polymerizable monomer.

[0023] Examples of polymerizable monomers other than (meth)acrylic acid include styrene; polymerizable styrene derivatives substituted at the α-position or aromatic ring, such as vinyltoluene and α-methylstyrene; alkyl (meth)acrylate; benzyl (meth)acrylate; benzyl (meth)acrylate derivatives; acrylamides such as diacetone acrylamide; acrylonitrile; vinyl alcohol esters such as vinyl-n-butyl ether; cycloalkyl (meth)acrylate; furfuryl (meth)acrylate; tetrahydrofurfuryl (meth)acrylate; isobornyl (meth)acrylate; adamantyl (meth)acrylate. Examples include: dicyclopentanyl (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 acid anhydride; maleic acid monoesters such as monomethyl maleic acid, monoethyl maleic acid, and monoisopropyl maleic acid; fumaric acid; cinnamic acid; α-cyanocinnamic acid; itaconic acid; crotonic acid; propiolic acid, etc.

[0024] Examples of benzyl (meth)acrylate derivatives include compounds in which the aromatic ring of the benzyl group is substituted with an alkoxy group having 1 to 6 carbon atoms, a halogen atom, and / or an alkyl group having 1 to 6 carbon atoms. Examples of benzyl (meth)acrylate derivatives include ethoxybenzyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, methylbenzyl (meth)acrylate, and ethylbenzyl (meth)acrylate.

[0025] Component (A) may have at least one structural unit derived from styrene or a styrene derivative, from the viewpoint of further improving resolution and adhesion. In this case, the resolution is further improved, and an even better resist shape can be obtained. Component (A) may have structural units derived from styrene and structural units derived from a styrene derivative.

[0026] Examples of hydroxyalkyl (meth)acrylates include hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxypentyl (meth)acrylate, and hydroxyhexyl (meth)acrylate. Furthermore, if the alkyl portion of the hydroxyalkyl (meth)acrylate unit has three or more carbon atoms, it may have a branched structure.

[0027] Component (A) may have at least one structural unit derived from alkyl (meth)acrylate from the viewpoint of improving alkali developability and peeling properties. Examples of alkyl groups of alkyl (meth)acrylate include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group. Any structural isomer can be used as the alkyl group. Examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. The number of carbon atoms in the alkyl group may be 1 to 4 from the viewpoint of further improving peeling properties. Alkyl (meth)acrylate can be used alone or in any combination of two or more types.

[0028] (A) The content of each structural unit constituting component (A) is not particularly limited. The content of structural units derived from (meth)acrylic acid may be such that the acid value of component (A) is within the following ranges. The acid value of component (A) may be 100 mg KOH / g or more, 120 mg KOH / g or more, 140 mg KOH / g or more, 150 mg KOH / g or more, or 160 mg KOH / g or more, from the viewpoint of suppressing the lengthening of the development time. The acid value of component (A) may be 250 mg KOH / g or less, 240 mg KOH / g or less, or 230 mg KOH / g or less, from the viewpoint of further improving the developer resistance (e.g., adhesion) of the cured product of the photosensitive resin composition. From these viewpoints, the acid value of component (A) may be 100-250 mg KOH / g, 120-240 mg KOH / g, 140-230 mg KOH / g, 150-230 mg KOH / g, or 160-230 mg KOH / g. Furthermore, when performing solvent development, a small amount of polymerizable monomer (monomer, such as (meth)acrylic acid) having a carboxyl group may be added for superior developability.

[0029] If component (A) has structural units derived from benzyl (meth)acrylate or a benzyl (meth)acrylate derivative, the content of such structural units may be within the following ranges based on the total solid content (total mass) of component (A). From the viewpoint of improving the chemical resistance of the resin, the above content may be 1% by mass or more, 15% by mass or more, or 20% by mass or more. From the viewpoint of suppressing a longer peeling time, the above content may be 80% by mass or less, 50% by mass or less, or 40% by mass or less. From these viewpoints, the above content may be 1 to 80% by mass, 15 to 50% by mass, or 20 to 40% by mass.

[0030] If component (A) has structural units derived from styrene or a styrene derivative, the content of such structural units may be within the following ranges based on the total solid content (total mass) of component (A). From the viewpoint of further improving resolution, the above content may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, or 45% by mass or more. From the viewpoint of suppressing the size of the peeling pieces and suppressing the length of the peeling time, the above content may be 65% by mass or less, 55% by mass or less, or 50% by mass or less. From these viewpoints, the above content may be 5-65% by mass, 10-55% by mass, 20-50% by mass, 25-50% by mass, 30-50% by mass, 35-50% by mass, 40-50% by mass, or 45-50% by mass.

[0031] Component (A) may have structural units derived from benzyl (meth)acrylate or a benzyl (meth)acrylate derivative, and structural units derived from styrene or a styrene derivative. In this case, a resist with better adhesion can be obtained.

[0032] If component (A) has structural units derived from alkyl (meth)acrylate, the content of such structural units may be within the following ranges based on the total solid content (total mass) of component (A). The above content may be 1% by mass or more, 2% by mass or more, or 3% by mass or more, from the viewpoint of suppressing the size of the peeling pieces and suppressing the length of the peeling time. The above content may be 80% by mass or less, 60% by mass or less, or 50% by mass or less, from the viewpoint of further improving resolution and adhesion. From these viewpoints, the above content may be 1 to 80% by mass, 2 to 60% by mass, or 3 to 50% by mass.

[0033] The weight-average molecular weight (Mw) of component (A) may be 10,000 or more, 20,000 or more, or 25,000 or more, from the viewpoint of further improving the developer resistance (e.g., adhesion) of the cured product of the photosensitive resin composition. The weight-average molecular weight (Mw) of component (A) may be 100,000 or less, 80,000 or less, or 60,000 or less, from the viewpoint of improving the development time. From these viewpoints, the weight-average molecular weight (Mw) of component (A) may be 10,000 to 100,000, 20,000 to 80,000, or 25,000 to 60,000. The weight-average molecular weight of component (A) is measured by gel permeation chromatography (GPC) (converted using a calibration curve with standard polystyrene). For compounds with low molecular weight, if it is difficult to measure the weight-average molecular weight using the above-described method, the molecular weight can be measured by other methods and its average can be calculated.

[0034] (A) The dispersion degree (Mw / Mn) of component (A) is not particularly limited, but may be between 1.0 and 3.0, or between 1.5 and 2.5. If the dispersion degree is 3.0 or less, adhesion and resolution will be further improved.

[0035] (A) Component may optionally have a characteristic group (such as a nitro group) within its molecule that is photosensitive to light having a wavelength in the range of 350 to 440 nm.

[0036] In the photosensitive resin composition according to this embodiment, one type of binder polymer may be used alone as component (A), or two or more types of binder polymers may be used in any combination. Examples of components (A) when two or more types are used in combination include two or more binder polymers consisting of different copolymer components (binder polymers containing different monomer units as copolymer components), two or more binder polymers with different weight-average molecular weights, and two or more binder polymers with different degrees of dispersion. As component (A), a polymer having a multimode molecular weight distribution as described in Japanese Patent Application Publication No. 11-327137 (Patent Document 3) can also be used.

[0037] The content of component (A) may be within the following ranges based on the total solid content (total mass) of the photosensitive resin composition. The content of component (A) may be 20% by mass or more, 30% by mass or more, 40% by mass or more, or 50% by mass or more, from the viewpoint of having excellent moldability of the film. The content of component (A) may be 90% by mass or less, 80% by mass or less, 65% by mass or less, or 60% by mass or less, from the viewpoint of having even better sensitivity and resolution. From these viewpoints, the content of component (A) may be 20-90% by mass, 30-80% by mass, 40-65% by mass, or 50-60% by mass.

[0038] The content of component (A) may be within the following ranges relative to 100 parts by mass of the total amount of components (A) and (B): From the viewpoint of further improving film formation, the content of component (A) may be 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, or 50 parts by mass or more. From the viewpoint of further improving sensitivity and resolution, the content of component (A) may be 70 parts by mass or less, 65 parts by mass or less, or 60 parts by mass or less. From these viewpoints, the content of component (A) may be 30 to 70 parts by mass, 35 to 65 parts by mass, 40 to 60 parts by mass, or 50 to 60 parts by mass.

[0039] ((B) component: photopolymerizable compound) Component (B) is a compound having at least one ethylenically unsaturated bond. Component (B) can be used alone or in any combination of two or more types. Component (B) may also contain at least one bisphenol A type (meth)acrylate compound from the viewpoint of further improving alkali developability, resolution and peelability after curing.

[0040] Examples of bisphenol A type (meth)acrylate compounds 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. In particular, component (B) may contain 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane from the viewpoint of further improving resolution and peeling properties. Bisphenol A type (meth)acrylate compounds can be used individually or in any combination of two or more types.

[0041] Of these, 2,2-bis(4-(methacryloxydiethoxy)phenyl)propane is commercially available as BPE-200 (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name). 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane is commercially available as BPE-500 (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name) or FA-321M (manufactured by Resonaq Corporation, trade name).

[0042] In the photosensitive resin composition according to this embodiment, the content of the bisphenol A type (meth)acrylate compound may be within the following ranges, based on the total solid content (total mass) of component (B), from the viewpoint of further improving the resolution of the resist pattern. The content may be 20% by mass or more, 40% by mass or more, 60% by mass or more, or 70% by mass or more. The content may be 100% by mass or less, or 95% by mass or less. From these viewpoints, the content may be 20-100% by mass, 40-100% by mass, 60-100% by mass, or 70-100% by mass, or 20-95% by mass, 40-95% by mass, 60-95% by mass, or 70-95% by mass.

[0043] Component (B) may include compounds obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid, from the viewpoint of improving resolution and flexibility in a balanced manner. Examples of compounds obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid include polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups; polypropylene glycol di(meth)acrylate having 2 to 14 propylene groups; alkylene glycol di(meth)acrylate having both (poly)oxyethylene groups and (poly)oxypropylene groups; 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. These compounds can be used individually, but to further improve resolution, two or more compounds selected from the group obtained by reacting the above-mentioned polyhydric alcohols with α,β-unsaturated carboxylic acids may be used in combination. Combining two or more compounds further improves resolution.

[0044] The content (total amount) of the above compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid may be within the following ranges, based on the total amount (total mass) of solids of component (B). The above content may be 5% by mass or more from the viewpoint of improving flexibility. The above content may be 20% by mass or less or 15% by mass or less from the viewpoint of further improving resolution. From these viewpoints, the above content may be 5 to 20% by mass or 5 to 15% by mass.

[0045] The photosensitive resin composition in this embodiment may further contain, as component (B), the above-mentioned bisphenol A type (meth)acrylate compound and other polymerizable compounds other than the above-mentioned compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid.

[0046] Other polymerizable compounds include nonylphenoxypolyethylene oxy(meth)acrylate, phthalate compounds, alkyl (meth)acrylates, and photopolymerizable compounds having at least one cationically polymerizable cyclic ether group in the molecule (such as oxetane compounds). Among these, at least one selected from the group consisting of nonylphenoxypolyethylene oxy(meth)acrylate and phthalate compounds is preferred from the viewpoint of improving resolution, adhesion, resist shape, and peelability after curing in a balanced manner.

[0047] Examples of the nonylphenoxypolyethylene oxy(meth)acrylates mentioned above include nonylphenoxytriethylene oxy(meth)acrylate, nonylphenoxytetraethylene oxy(meth)acrylate, nonylphenoxypentaethylene oxy(meth)acrylate, nonylphenoxyhexaethylene oxy(meth)acrylate, nonylphenoxyheptaethylene oxy(meth)acrylate, nonylphenoxyoctaethylene oxy(meth)acrylate, nonylphenoxynonaethylene oxy(meth)acrylate, nonylphenoxydecaethylene oxy(meth)acrylate, and nonylphenoxyundaethylene oxy(meth)acrylate. Nonylphenoxypolyethylene oxy(meth)acrylates can be used individually or in any combination of two or more types.

[0048] Examples of phthalate 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. Among these, γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate is preferred as the phthalate compound. γ-chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate is commercially available as FA-MECH (manufactured by Resonaq Corporation, trade name). The phthalate compounds can be used individually or in any combination of two or more types.

[0049] If the photosensitive resin composition according to this embodiment contains the above-mentioned other photopolymerizable compounds as component (B), the content of the photopolymerizable compounds may be 1 to 30% by mass, 3 to 25% by mass, or 5 to 20% by mass, based on the total solid content (total mass) of component (B), from the viewpoint of improving resolution, adhesion, resist shape, and peelability after curing in a balanced manner.

[0050] The content of component (B) may be within the following ranges based on the total solid content (total mass) of the photosensitive resin composition. The content of component (B) may be 3% by mass or more, 10% by mass or more, 25% by mass or more, 30% by mass or more, or 40% by mass or more, from the viewpoint of having a tendency to be even better in sensitivity and resolution. The content of component (B) may be 70% by mass or less, 60% by mass or less, or 50% by mass or less, from the viewpoint of having a tendency to be good in terms of film moldability. From these viewpoints, the content of component (B) may be 3 to 70% by mass, 10 to 60% by mass, 25 to 50% by mass, 30 to 50% by mass, or 40 to 50% by mass.

[0051] The content of component (B) may be within the following ranges relative to 100 parts by mass of the total amount of components (A) and (B). The content of component (B) may be 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, or 40 parts by mass or more, from the viewpoint of further improving sensitivity and resolution. The content of component (B) may be 70 parts by mass or less, 65 parts by mass or less, 60 parts by mass or less, 50 parts by mass or less, or 45 parts by mass or less, from the viewpoint of further improving film formation. From these viewpoints, the content of component (B) may be 5 to 70 parts by mass, 10 to 70 parts by mass, 15 to 65 parts by mass, 20 to 60 parts by mass, 30 to 50 parts by mass, or 40 to 45 parts by mass.

[0052] ((C) component: photopolymerization initiator) The photosensitive resin composition according to this embodiment contains an oxime ester-based photopolymerization initiator as component (C). This makes it possible to reduce the deviation of the resist line width obtained from the design value when forming a resist pattern, whether using a mask exposure method or a direct writing method.

[0053] The oxime ester-based photopolymerization initiator is not particularly limited as long as it has an oxime ester group, but it is preferably a compound having at least one of a carbazole structure, a phenyl sulfide structure, and a fluorene structure. This makes it possible to further reduce the deviation of the obtained resist line width from the design value when forming a resist pattern, whether using a mask exposure method or a direct writing method. The oxime ester-based photopolymerization initiator can be used alone or in any combination of two or more types.

[0054] Examples of oxime ester-based photopolymerization initiators having a carbazole structure include 1-propanone,3-cyclopentyl-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o-acetyloxime) (trade name "TR-PBG-304", manufactured by Changzhou Strong Electronic New Materials Co., Ltd.), 1-propanone,3-cyclopentyl-1-[2-(2-pyrimidinylthio)-9H-carbazole-3-yl]-,1-(o-acetyloxime) (trade name "TR-PBG-314", manufactured by Changzhou Strong Electronic New Materials Co., Ltd.), and 2-(acetoxyimino)-1-(6-(2-(acetoxyimino)-3-cyclohexylpropionyl)-9-ethylcarbazole-3-yl)n-octan-1-one. Examples of commercially available products include TR-PBG-304, TR-PBG-314, and TR-PBG-345 (all manufactured by Changzhou Strong Electronic New Materials Co., Ltd.).

[0055] Examples of oxime ester-based photopolymerization initiators having a phenyl sulfide structure include 1-[4-(phenylthio)phenyl]-3-cyclopentylpropane-1,2-dione-2-(o-benzoyl oxime) (trade name "TR-PBG-305", manufactured by Changzhou Strong Electronic New Materials Co., Ltd.). Commercially available products include TR-PBG-305 and TR-PBG-3057 (both manufactured by Changzhou Strong Electronic New Materials Co., Ltd.).

[0056] Examples of oxime ester-based photopolymerization initiators having a fluorene structure include [(Z)-[3-cyclohexyl-1-(9,9-dibutyl-7-nitrofluorene-2-yl)propyridene]amino)acetate. A commercially available example is TR-PBG-358 (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.).

[0057] Oxime ester-based photopolymerization initiators may be compounds that do not possess any of the carbazole, phenyl sulfide, or fluorene structures. Examples of such oxime ester-based photopolymerization initiators include 1-phenyl-1,2-propanedione-2-o-benzoyl oxime.

[0058] The content of the oxime ester-based photopolymerization initiator is 0.3 parts by mass or more per 100 parts by mass of the total of components (A) and (B). This reduces the deviation of the resist line width from the design value when forming a resist pattern, regardless of whether a mask exposure method or a direct writing method is used. From the viewpoint of further enhancing the above effect, the content of the oxime ester-based photopolymerization initiator may be 0.35 parts by mass or more, or 0.4 parts by mass or more, per 100 parts by mass of the total of components (A) and (B). Furthermore, from the viewpoint of obtaining appropriate sensitivity, the content of the oxime ester-based photopolymerization initiator may be 3.0 parts by mass or less, 2.5 parts by mass or less, or 2.0 parts by mass or less, per 100 parts by mass of the total of components (A) and (B). From these viewpoints, the content of the oxime ester-based photopolymerization initiator may be 0.3 to 3.0 parts by mass, 0.35 to 2.5 parts by mass, or 0.4 to 2.0 parts by mass, per 100 parts by mass of the total of components (A) and (B).

[0059] From the viewpoint of obtaining appropriate sensitivity, the content of the oxime ester-based photopolymerization initiator may be within the following ranges based on the total mass of component (C): The content of the oxime ester-based photopolymerization initiator may be 50% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, or 75% by mass or more. The content of the oxime ester-based photopolymerization initiator may be 100% by mass. That is, the (C) photopolymerization initiator may consist only of the oxime ester-based photopolymerization initiator. From these viewpoints, the above content may be 50-100% by mass, 60-100% by mass, 65-100% by mass, 70-100% by mass, or 75-100% by mass.

[0060] The photosensitive resin composition according to this embodiment may further contain other photopolymerization initiators other than oxime ester-based photopolymerization initiators. Examples of other photopolymerization initiators include hexaarylbiimidazole derivatives. From the viewpoint of further improving sensitivity and adhesion, at least one 2,4,5-triarylimidazole dimer is preferred as the above photopolymerization initiator. The structure of the above 2,4,5-triarylimidazole dimer may be symmetric or asymmetric.

[0061] Examples of the 2,4,5-triarylimidazole dimers mentioned above include 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer (also known as 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole), 2-(o-chlorophenyl)-4,5-bis-(m-methoxyphenyl)imidazole dimer, and 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer. Among these, 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer is preferred.

[0062] Other photopolymerization initiators include aromatic ketones such as benzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 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; alkylanes Examples include quinones such as traquinone; benzoin ether compounds such as benzoin alkyl ethers; benzoin compounds such as benzoin and alkylbenzoin; benzyl derivatives such as benzyldimethylketal; bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; bis(2,6-dimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide; and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide.

[0063] If the photosensitive resin composition according to this embodiment contains the above-mentioned other photopolymerization initiators, the amount of such photopolymerization initiator may be 0.01 to 10 parts by mass, 0.01 to 8 parts by mass, or 0.01 to 5 parts by mass per 100 parts by mass of the total of components (A) and (B).

[0064] (C) The content of component (C) may be within the following ranges, based on the total solid content (total mass) of the photosensitive resin composition, from the viewpoint of further improving sensitivity and adhesion. The content of component (C) may be 0.1% by mass or more, 0.2% by mass or more, 0.3% by mass or more, or 0.35% by mass or more. The content of component (C) may be 20% by mass or less, 10% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, or 0.4% by mass or less. From these viewpoints, the content of component (C) may be 0.1 to 20% by mass, 0.1 to 10% by mass, or 0.1 to 3% by mass.

[0065] (Component D: Hydrogen donor) The photosensitive resin composition according to this embodiment may further contain a hydrogen donor that can supply hydrogen during the reaction of the exposed area. This further improves the sensitivity of the photosensitive resin composition.

[0066] Examples of component (D) include bis[4-(dimethylamino)phenyl]methane, bis[4-(diethylamino)phenyl]methane, leucocrystal violet, and N-phenylglycine. Component (D) can be used individually or in any combination of two or more types.

[0067] If the photosensitive resin composition according to this embodiment contains component (D), the content of component (D) may be within the following ranges relative to 100 parts by mass of the total amount of components (A) and (B). From the viewpoint of further improving sensitivity, the content of component (D) may be 0.01 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, 0.3 parts by mass or more, 0.5 parts by mass or more, or 0.6 parts by mass or more. From the viewpoint of suppressing the precipitation of excess component (D) as foreign matter after film formation, the content of component (D) may be 10 parts by mass or less, 5 parts by mass or less, 2 parts by mass or less, or 1 part by mass or less. From these viewpoints, the content of component (D) may be 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, or 0.1 to 2 parts by mass.

[0068] (Sensitizing dye) The photosensitive resin composition according to this embodiment may further contain a sensitizing dye. This further improves the sensitivity of the photosensitive resin composition. Examples of sensitizing dyes include dialkylaminobenzophenones, pyrazolines, anthracenes, coumarins, xanthones, oxazoles, benzoxazoles, thiazoles, benzothiazoles, triazoles, stilbenes, triazines, thiophenes, naphthalimides, and triarylamines. The sensitizing dye can be used alone or in any combination of two or more types.

[0069] In particular, when exposing a photosensitive resin layer using active light with a wavelength of 390-420 nm, the sensitizing dye may include at least one selected from the group consisting of pyrazolines, anthracenes, coumarins, and triarylamines, from the viewpoint of further superior sensitivity and adhesion, and in particular may include at least one selected from the group consisting of pyrazolines, anthracenes, and triarylamines.

[0070] If the photosensitive resin composition according to this embodiment contains a sensitizing dye, the amount of the sensitizing dye may be 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, or 0.1 to 3 parts by mass per 100 parts by mass of the total amount of components (A) and (B). A sensitizing dye content of 0.01 parts by mass or more further improves sensitivity and resolution. A sensitizing dye content of 10 parts by mass or less further suppresses the formation of an inverted trapezoidal resist shape, thereby further improving adhesion.

[0071] (Other ingredients) The photosensitive resin composition according to this embodiment may contain other components in addition to the above components, as needed. Examples of other components include dyes (such as malachite green), tribromophenylsulfone, photochromic agents, thermal color inhibitors, plasticizers (such as p-toluenesulfonamide), pigments, fillers, defoamers, flame retardants, stabilizers, adhesion promoters, leveling agents, release accelerators, antioxidants, fragrances, imaging agents, and thermal crosslinking agents. These can be used individually or in any combination of two or more types.

[0072] The content of each of these components is preferably about 0.01 to 20 parts by mass per 100 parts by mass of the total amount of component (A) and component (B).

[0073] The content of dyes and pigments may be less than 0.5% by mass and 0.45% by mass or less, based on the solid content (total mass) of the photosensitive resin composition.

[0074] The photosensitive resin composition according to this embodiment may optionally contain at least one organic solvent to adjust its viscosity. Any commonly used organic solvent can be used without particular limitation. Examples of organic solvents include methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, propylene glycol monomethyl ether, and mixtures thereof.

[0075] The photosensitive resin composition according to this embodiment can be used, for example, by dissolving at least component (A), component (B), and component (C) in the above organic solvent to form a solution with a solid content of about 30 to 60% by mass (hereinafter referred to as "coating solution").

[0076] The above coating solution can be used, for example, to form a photosensitive resin layer as follows: By applying the above coating solution to the surface of a support (support film, metal plate, etc.) described later and drying it, a photosensitive resin layer derived from the above photosensitive resin composition can be formed on the support. Examples of metal plates include copper, copper alloys, nickel, chromium, iron, and iron alloys (stainless steel, etc.), and preferably copper, copper alloys, iron alloys, etc.

[0077] The thickness of the photosensitive resin layer varies depending on the application, but it may be approximately 1 to 100 μm after drying.

[0078] The photosensitive resin composition according to this embodiment can be suitably used, for example, in a resist pattern formation method described later. In particular, it is suitable for application in a method of forming a conductive pattern (circuit) by plating.

[0079] <Photosensitive element> The photosensitive element according to this embodiment comprises a support and a photosensitive resin layer disposed on the support. The photosensitive resin layer includes a photosensitive resin composition according to this embodiment or a cured product thereof. The photosensitive resin layer is formed using the photosensitive resin composition according to this embodiment, and the photosensitive resin composition may be in an uncured state (coating film). The photosensitive element may optionally include other layers such as a protective layer. For example, the surface of the photosensitive resin layer opposite to the surface facing the support may be covered with a protective layer (protective film, etc.).

[0080] Figure 1 shows one embodiment of a photosensitive element. In the photosensitive element 1 shown in Figure 1, a support 2, a photosensitive resin layer 3, and a protective layer 4 are laminated in this order. The photosensitive element 1 can be obtained, for example, as follows: A coating liquid, which is a photosensitive resin composition, is applied to the support 2 to form a coating layer, and then the coating layer is dried to form a photosensitive resin layer 3. Next, the side of the photosensitive resin layer 3 opposite to the support 2 is covered with a protective layer 4 to obtain a photosensitive element 1 comprising a support 2, a photosensitive resin layer 3 formed on the support 2, and a protective layer 4 laminated on the photosensitive resin layer 3. The photosensitive element 1 does not necessarily have to include a protective layer 4.

[0081] As the support, polymer films with heat resistance and solvent resistance, such as polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film, can be used.

[0082] The thickness of the above-mentioned support (support film, etc.) may be 1 to 100 μm, 5 to 50 μm, or 5 to 30 μm. A support thickness of 1 μm or more makes it easy to prevent the support from tearing when peeling it off. A support thickness of 100 μm or less makes it easy to prevent a decrease in resolution when exposure is performed through the support.

[0083] The protective layer (protective film, etc.) described above preferably has an adhesive strength to the photosensitive resin layer that is less than the adhesive strength to the photosensitive resin layer of the support, and a low-fish-eye film is also preferred. Here, "fish-eye" refers to the incorporation of foreign matter, undissolved material, oxidatively degraded material, etc., into the film when the material constituting the protective film is heat-melted, kneaded, extruded, biaxially stretched, cast, etc. In other words, "low-fish-eye" means that there is a small amount of the above-mentioned foreign matter, etc., in the film.

[0084] Specifically, the protective layer can be a polymer film having heat resistance and solvent resistance, such as polyethylene terephthalate film, polyethylene film, polypropylene film, or polyester film. Examples of commercially available polymer films include polypropylene films from Oji Paper Co., Ltd. (e.g., Alphan MA-410 and E-200C) and Shin-Etsu Film Co., Ltd., and polyethylene terephthalate films such as Teijin Limited's PS-25 (e.g., PS series). The protective layer may be made of the same type of material as the support, or of a different type.

[0085] The thickness of the protective layer may be 1 to 100 μm, 5 to 50 μm, 5 to 30 μm, or 15 to 30 μm. A protective layer thickness of 1 μm or more helps to prevent tearing of the protective layer when laminating the photosensitive resin layer and support onto the substrate (such as a substrate) while peeling off the protective layer. A protective layer thickness of 100 μm or less improves productivity.

[0086] The photosensitive element according to this embodiment can be manufactured, for example, as follows. The photosensitive element can be manufactured by a manufacturing method comprising the steps of: dissolving at least component (A), component (B), and component (C) in an organic solvent to prepare a coating solution with a solid content of about 30 to 60% by mass; applying the coating solution onto a support to form a coating layer; and drying the coating layer to form a photosensitive resin layer.

[0087] The above coating solution can be applied to the support by known methods such as roll coating, comma coating, gravure coating, air knife coating, die coating, and bar coating. The drying of the coating layer is not particularly limited as long as at least a portion of the organic solvent can be removed from the coating layer. For example, drying may be carried out at 70 to 150°C for about 5 to 30 minutes. The amount of residual organic solvent in the photosensitive resin layer after drying may be 2% by mass or less, from the viewpoint of preventing the diffusion of the organic solvent in subsequent processes.

[0088] The thickness of the photosensitive resin layer in the photosensitive element according to this embodiment can be appropriately selected depending on the application, but the thickness after drying may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm. A photosensitive resin layer thickness of 1 μm or more facilitates industrial coating and improves productivity. A photosensitive resin layer thickness of 100 μm or less further improves adhesion and resolution.

[0089] The photosensitive element according to this embodiment may further include known intermediate layers such as a cushion layer, adhesive layer, light-absorbing layer, or gas barrier layer, as needed.

[0090] The form of the photosensitive element according to this embodiment is not particularly limited. The photosensitive element may be, for example, in the form of a sheet, or it may be wound in a roll on a core.

[0091] The photosensitive element according to this embodiment can be suitably used, for example, in a resist pattern formation method described later. In particular, it is suitable for application in a method of forming a conductor pattern (circuit) by plating.

[0092] <Method for forming a resist pattern> The method for forming a resist pattern according to this embodiment comprises: (i) a step of forming a photosensitive resin layer on a substrate (such as a substrate) using the above-mentioned photosensitive resin composition or the above-mentioned photosensitive element (photosensitive resin layer formation step); (ii) a step of curing the photosensitive resin layer by irradiating at least a part of the photosensitive resin layer with active light (exposure step); and (iii) a step of removing the uncured portion of the photosensitive resin layer from the substrate to form a resist pattern (development step), and additional steps as necessary. The resist pattern can also be called a relief pattern. The method for forming a resist pattern according to this embodiment can also be called a method for manufacturing a substrate with a resist pattern.

[0093] ((i) Photosensitive resin layer formation step) In the photosensitive resin layer formation process, a photosensitive resin layer is formed on a substrate (such as a substrate) using the above-mentioned photosensitive resin composition or photosensitive element. The above-mentioned substrate is not particularly limited, but examples include a substrate having a conductive layer. As a substrate having a conductive layer, a circuit formation substrate comprising an insulating layer and a conductive layer formed on the insulating layer, or a die pad (a substrate for a lead frame; such as an alloy substrate) can be used.

[0094] One method for forming a photosensitive resin layer on a substrate (such as a circuit board) is to remove the protective layer from the photosensitive element and then press the photosensitive resin layer of the photosensitive element onto the substrate while heating it. This yields a laminate consisting of a substrate, a photosensitive resin layer, and a support, which are stacked in that order. Alternatively, the photosensitive resin layer may be formed by coating and drying the photosensitive resin composition.

[0095] This photosensitive resin layer formation process is preferably carried out under reduced pressure from the viewpoint of even better adhesion and conformability. The photosensitive resin layer and / or substrate (substrate, etc.) may be heated at a temperature of 70 to 130°C during bonding. The bonding pressure should be approximately 0.1 to 1.0 MPa (1 to 10 kgf / cm²). 2 The process may be carried out under a pressure of approximately [amount]. These conditions can be selected as appropriate as needed. Although preheating the substrate is not necessary if the photosensitive resin layer is heated to 70-130°C, preheating the substrate can be performed to further improve adhesion and conformability.

[0096] (ii) Exposure process In the exposure process, at least a portion of the photosensitive resin layer formed on the substrate (such as a paper substrate) is irradiated with active light, causing the irradiated portion to harden and form a latent image.

[0097] In this case, if the support present on the photosensitive resin layer is transparent to active light, the active light can be irradiated through the support. If the support is light-shielding, the active light can be irradiated onto the photosensitive resin layer after the support has been removed.

[0098] As for the exposure method, a method of irradiating active light in an image pattern using direct drawing exposure methods such as LDI (Laser Direct Imaging) exposure or DLP (Digital Light Processing) exposure may be employed, or a method of irradiating active light in an image pattern via a negative or positive mask pattern called artwork (mask exposure method) may be employed, or these may be used in combination.

[0099] As the light source for the active light, any known light source can be used. For example, light sources that effectively emit ultraviolet or visible light, such as carbon arc lamps, mercury vapor arc lamps, high-pressure mercury lamps, xenon lamps, gas lasers (argon lasers, etc.), solid-state lasers (YAG lasers, etc.), and semiconductor lasers, can be used. Examples of the dominant wavelength of the active light include 355 nm and 405 nm. The dominant wavelength refers to the set wavelength of the active light; for example, light with a dominant wavelength of 355 nm may include light with wavelengths of 352 to 358 nm.

[0100] ((iii) Development process) In the development process, the uncured portion of the photosensitive resin layer is removed from the substrate (such as a paper substrate), thereby forming a resist pattern on the substrate consisting of the cured photosensitive resin layer. If a support is present on the photosensitive resin layer, the support is removed before removing (developing) the unexposed portions other than the exposed portions. Development methods include wet development and dry development, but wet development is widely used.

[0101] When using wet development, development can be carried out using a developer solution corresponding to the photosensitive resin composition and a known development method. Development methods include the dip method, paddle method, spray method, brushing, slapping, scrubbing, and agitation immersion, among others. From the viewpoint of further improving resolution, the high-pressure spray method is most suitable. Two or more of these methods may be combined for development.

[0102] The composition of the developer can be appropriately selected according to the composition of the photosensitive resin composition described above. Examples of developers include alkaline aqueous solutions and organic solvent developers.

[0103] Alkaline aqueous solutions are safe, stable, and easy to handle when used as developing solutions. Examples of bases in alkaline aqueous solutions 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-diamino-2-propanol; and morpholine.

[0104] Preferred alkaline aqueous solutions include dilute solutions of 0.1-5% by mass sodium carbonate, 0.1-5% by mass potassium carbonate, 0.1-5% by mass sodium hydroxide, and 0.1-5% by mass sodium tetraborate. The pH of the alkaline aqueous solution is preferably 9-11. The temperature of the alkaline aqueous solution is adjusted to match the alkaline developability of the photosensitive resin layer. Surface surfactants, defoamers, and small amounts of organic solvents to promote development may be added to the alkaline aqueous solution.

[0105] Examples of organic solvents include acetone, ethyl acetate, alkoxyethanol having alkoxy groups with 1 to 4 carbon atoms, ethyl alcohol, isopropyl alcohol, butyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether. Organic solvents can be used individually or in any combination of two or more. The content of the organic solvent in the aqueous developer is usually preferably 2 to 90% by mass, and its temperature can be adjusted according to the alkaline developing properties.

[0106] Examples of organic solvent developers include 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexanone, methyl isobutyl ketone, and γ-butyrolactone. It is preferable to add water to the organic solvent in an amount of 1 to 20% by mass to prevent ignition.

[0107] In this embodiment, after removing the unexposed areas in the development process, heating to approximately 60-250°C or 0.2-10 J / cm² is performed as needed. 2 The resist pattern may be further hardened by exposure to a certain extent.

[0108] <Manufacturing method for printed circuit boards> The method for manufacturing a printed circuit board according to this embodiment comprises the steps of forming a resist pattern on a substrate (such as a substrate) by the resist pattern formation method described above, and forming a conductor pattern by applying a plating or etching treatment to the substrate (such as a substrate) and the member having the resist pattern (a substrate on which the resist pattern is formed, a substrate with a resist pattern). Furthermore, the method for manufacturing a printed circuit board according to this embodiment may include other steps, such as a step of removing the resist pattern, as needed.

[0109] In this embodiment, for example, a resist pattern formed on a substrate (such as a substrate) can be used as a mask to perform plating or etching on the substrate (for example, a conductive layer provided on the substrate).

[0110] In the manufacturing method of printed circuit boards, the plating treatment may be either electrolytic plating or electroless plating, or both, with electroless plating being preferred. Examples of electroless plating treatments include copper plating such as copper sulfate plating and copper pyrophosphate plating; solder plating such as high-slow solder plating; Watt bath (nickel sulfate-nickel chloride) plating; nickel plating such as nickel sulfamate; and gold plating.

[0111] In the step of removing the resist pattern, the resist pattern can be removed using an aqueous solution that is even more strongly alkaline than the alkaline aqueous solution used in the development step described above. Examples of such strongly alkaline aqueous solutions include 1-10% by mass sodium hydroxide aqueous solution and 1-10% by mass potassium hydroxide aqueous solution. Methods for this include immersion methods and spray methods, which may be used individually or in combination.

[0112] The etching method can be appropriately selected depending on the conductive layer (metal layer) to be removed. Examples of etching solutions include cupric chloride solution, ferric chloride solution, alkaline etching solution, and hydrogen peroxide etching solution. Among these, ferric chloride solution is preferred from the viewpoint of having a good etch factor.

[0113] The printed circuit board manufactured by the printing circuit board manufacturing method according to this embodiment may be a multilayer printed circuit board and may also have small-diameter through-holes.

[0114] The printed circuit board according to this embodiment can be manufactured by a manufacturing method that includes an etching process or an etching process to form a conductor pattern on a substrate on which a resist pattern has been formed by the resist pattern formation method according to this embodiment. Hereinafter, an example of the manufacturing process of a printed circuit board by the semi-additive method will be described with reference to Figure 2.

[0115] Figure 2(a) shows a substrate (circuit formation substrate) prepared, in which a conductive layer 10 is formed on an insulating layer 15. The conductive layer 10 is, for example, a metallic copper layer. Figure 2(b) shows that a photosensitive resin layer 32 is formed on the conductive layer 10 of the substrate by the photosensitive resin layer formation process described above. Figure 2(c) shows that a mask 20 is placed on the photosensitive resin layer 32, and an active light 50 is irradiated to expose the area other than the area where the mask 20 is placed, thereby forming a photocurable area. Figure 2(d) shows that the area other than the photocurable area formed by the exposure process is removed from the substrate by the development process, thereby forming a resist pattern 30, which is the photocurable area, on the substrate. Figure 2(e) shows that a plating layer 42 is formed on the conductive layer 10 by a plating process using the resist pattern 30, which is the photocurable area, as a mask. In Figure 2(f), the resist pattern 30, which is the photocurable portion, is removed with a strong alkaline aqueous solution, and then a portion of the plating layer 42 and the conductive layer 10 that was masked by the resist pattern 30 are removed by flash etching to form the conductive pattern 40. The conductive layer 10 and the plating layer 42 may be made of the same material or different materials. If the conductive layer 10 and the plating layer 42 are made of the same material, the conductive layer 10 and the plating layer 42 may be integrated. In Figure 2, a method for forming the resist pattern 30 using a mask 20 is described, but the resist pattern 30 may also be formed by direct exposure without using a mask 20. [Examples]

[0116] The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to these examples.

[0117] [Examples 1-7 and Comparative Examples 1-6] <Preparation of photosensitive resin composition> The materials shown in Tables 1 and 2 were mixed in the amounts (parts by mass) shown in the same tables to prepare solutions of the photosensitive resin composition. Note that the amounts (parts by mass) of components other than the solvent shown in Tables 1 and 2 represent the mass of non-volatile components (solid content). Details of each component shown in Tables 1 and 2 are as follows.

[0118] ((A) Binder polymer) A-1: Propylene glycol monomethyl ether / toluene (mass ratio 3 / 4) solution of copolymer of methacrylic acid / styrene / benzyl methacrylate / 2-hydroxyethyl methacrylate (mass ratio: 27 / 50 / 20 / 3, Mw: 35000, acid value: 176.1 mgKOH / g, Tg: 106.8℃) (solids content: 49.6% by mass) A-2: Propylene glycol monomethyl ether / toluene (mass ratio 3 / 4) solution of copolymer of methacrylic acid / methyl methacrylate / styrene / benzyl methacrylate (mass ratio: 27 / 5 / 45 / 23, Mw: 51000, acid value: 176.1 mgKOH / g, Tg: 107.0℃) (solids content: 47% by mass)

[0119] ((B) Photopolymerizable compound) FA-321M: 2,2-Bis(4-(methacryloxypentaethoxy)phenyl)propane (manufactured by Resonaq Corporation, number of EO groups: 10 (average value)) BP-2EM: 2,2-bis(4-(methacryloxypolyethoxy)phenyl)propane (EO group: 2.6 (total value), manufactured by Kyoeisha Chemical Co., Ltd.) BPE-200: 2,2-Bis(4-(methacryloxydiethoxy)phenyl)propane (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) FA-024M: Polyalkylene glycol dimethacrylate (manufactured by Resonac Corporation, number of EO groups: 12 (average), number of PO groups: 6 (average)) FA-023M: Polyalkylene glycol dimethacrylate (manufactured by Resonac Co., Ltd., number of EO groups: 6 (average value), number of PO groups: 12 (average value)) FA-MECH: γ-chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate (manufactured by Resonaq Corporation)

[0120] ((C) Photopolymerization initiator) B-CIM: 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (manufactured by Changzhou Strong Electronics New Materials Co., Ltd.) TR-PBG-304: An oxime ester-based photopolymerization initiator having a carbazole structure represented by the following formula (1) (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) [ka] TR-PBG-305: Oxime ester-based photopolymerization initiator having a phenyl sulfide structure represented by the following formula (2) (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) [ka] TR-PBG-314: An oxime ester-based photopolymerization initiator having a carbazole structure represented by the following formula (3) (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) [ka] TR-PBG-345: An oxime ester-based photopolymerization initiator having a carbazole structure represented by the following formula (4) (manufactured by Changzhou Strong Electronics New Materials Co., Ltd.) [ka] TR-PBG-358: Oxime ester-based photopolymerization initiator having a fluorene structure represented by the following formula (5) (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) [ka] TR-PBG-365: Oxime ester-based photopolymerization initiator having a fluorene structure (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) TR-PBG-3057: Oxime ester-based photopolymerization initiator having a phenyl sulfide structure represented by the following formula (6) (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.) [ka]

[0121] (Other ingredients) DBA: 9,10-Dibutoxyanthracene (manufactured by Kawasaki Chemical Industries, Ltd.) TBC: 4-tert-butylcatechol (manufactured by DIC Corporation) (polymerization inhibitor) LCV: Leucocrystal violet (Yamada Chemical Industries Co., Ltd.) (colorant) MKG: Malachite Green (manufactured by Osaka Organic Chemical Industry Co., Ltd.) (dye) LA-7RD: 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (manufactured by Adeka Co., Ltd.) FA-711MM: 1,2,2,6,6-Pentamethylpiperidine-4-yl methacrylate (manufactured by Resonaq Corporation) SF-808H: A mixture of carboxybenzotriazole, 5-amino-1H-tetrazole, and methoxypropanol (manufactured by Sanwa Chemical Co., Ltd.)

[0122] <Fabrication of photosensitive elements> Each of the photosensitive resin compositions obtained above was applied to a 16 μm thick polyethylene terephthalate film (Toray Industries, Inc., product name "FS-31", support) so as to ensure uniform thickness. Next, it was dried in a hot air convection dryer at 80°C and 120°C to form a photosensitive resin layer with a thickness of 25 μm after drying. A polyethylene film (Tamapoly Co., Ltd., product name "NF-15") (protective layer) was laminated onto this photosensitive resin layer to obtain a photosensitive element in which the support, photosensitive resin layer, and protective layer were laminated in that order.

[0123] <Fabrication of laminates> A copper-clad laminate (substrate, manufactured by Resonaq Corporation, product name "MLC-E-67"), which is a glass epoxy material with copper foil (thickness: 35 μm) laminated on both sides, was sequentially washed with water, pickled, and washed with water again, and then dried with an airflow. This copper-clad laminate was heated to 80°C. While peeling off the protective layer, the photosensitive elements obtained above were laminated so that the photosensitive resin layer was in contact with the copper surface. This resulted in laminates in which the copper-clad laminate, photosensitive resin layer, and support were laminated in that order. The obtained laminates were used as test pieces in the resist line width accuracy evaluation test shown below. The lamination was performed using a 110°C heat roll with a pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0124] <Measuring the minimum development time> After cutting the aforementioned laminate into a square shape (5cm x 5cm), test specimens were obtained by peeling off the support. Next, the unexposed photosensitive resin layer on the test specimen was spray-developed at a pressure of 0.18 MPa using a 1% by mass aqueous sodium carbonate solution at 30°C (nozzle: full cone type, distance between the object to be treated and the nozzle tip: 6cm), and the shortest time at which the removal of the unexposed photosensitive resin layer could be visually confirmed was obtained as the minimum development time (MD).

[0125] <Evaluation of resist line width accuracy (mask exposure method)> A 41-step tablet (manufactured by Resonac Co., Ltd.) and a photomask (a photomask with lines of 10 μm width) were placed on the support of the test specimen described above. Using a parallel beam exposure machine (manufactured by Oak Manufacturing Co., Ltd., product name: EXM1201), ultraviolet light was irradiated from above and perpendicular to the photomask surface at an energy level that resulted in 15 steps remaining on the 41-step tablet. After that, the support was peeled off and spray-developed for twice the minimum development time obtained by the method described above to remove the unexposed areas. This formed a resist pattern, which is a photocured product of a photosensitive resin composition, on the copper-clad laminate. The line width of the obtained resist pattern was measured at three locations, and the average value was taken as the measured line width (unit: μm). The ratio of the measured value to the design value of the photomask line width (10 μm) (measured value / design value) was calculated. This ratio (measured value / design value) is shown in Tables 1 and 2 as the accuracy of the resist line width. The closer this value is to 1, the less the resulting resist line width deviates from the design value.

[0126] [Table 1]

[0127] [Table 2]

[0128] [Examples 8-12 and Comparative Examples 7-10] <Preparation of photosensitive resin composition> A solution of the photosensitive resin composition was prepared by mixing each material shown in Table 3 in the proportions (unit: parts by mass) shown in the same table. Note that the proportions (parts by mass) of components other than the solvent shown in Table 3 refer to the mass of non-volatile components (solid content). Details of each component shown in Table 3 are as follows. However, the details of the components that are the same as those shown in Tables 1 and 2 are as described above.

[0129] ((A) Binder polymer) A-3: Acetone / propylene glycol monomethyl ether solution (mass ratio 6 / 1) of a copolymer of methacrylic acid / methyl methacrylate / styrene / benzyl methacrylate (mass ratio: 27 / 5 / 45 / 23, Mw: 47000, acid value: 176.1 mgKOH / g, Tg: 107.0℃) (solids content: 47% by mass)

[0130] ((C) Photopolymerization initiator) C-1: Oxime ester-based photopolymerization initiator having a carbazole structure represented by the following formula (7) (manufactured by Nippon Chemical Laboratories Co., Ltd.) [ka]

[0131] <Fabrication of photosensitive elements> Each of the photosensitive resin compositions obtained above was applied to a 16 μm thick polyethylene terephthalate film (Toray Industries, Inc., product name "FS-31", support) so as to ensure uniform thickness. Next, it was dried in a hot air convection dryer at 80°C and 120°C to form a photosensitive resin layer with a thickness of 25 μm after drying. A polyethylene film (Tamapoly Co., Ltd., product name "NF-15") (protective layer) was laminated onto this photosensitive resin layer to obtain a photosensitive element in which the support, photosensitive resin layer, and protective layer were laminated in that order.

[0132] <Fabrication of laminates> A copper-clad laminate (substrate, manufactured by Resonaq Corporation, product name "MLC-E-679"), which is a glass epoxy material with copper foil (thickness: 35 μm) laminated on both sides, was sequentially washed with water, pickled, and washed with water again, and then dried with an airflow. This copper-clad laminate was heated to 80°C. While peeling off the protective layer, the photosensitive elements obtained above were laminated so that the photosensitive resin layer was in contact with the copper surface. This resulted in laminates in which the copper-clad laminate, photosensitive resin layer, and support were laminated in that order. The obtained laminates were used as test pieces in the resist line width accuracy evaluation test shown below. The lamination was performed using a 110°C heat roll with a pressing pressure of 0.4 MPa and a roll speed of 1.0 m / min.

[0133] <Evaluation of Resist Line Width Accuracy (Direct Drawing Method)> A 41-step tablet (manufactured by Resonac Co., Ltd.) was placed on the support of the test specimen described above. Next, using an LDI exposure machine (main wavelength 405 nm, manufactured by Adtec Engineering Co., Ltd., product name "DE-1UH"), the 41-step tablet was exposed at an energy level that resulted in 15 remaining steps. Then, the support was peeled off and spray-developed for twice the minimum development time obtained by the above method to remove the unexposed areas. This formed a resist pattern (design line width: 10 μm), which is a photocured product of a photosensitive resin composition, on the copper-clad laminate. The line width of the obtained resist pattern was measured at three locations, and the average value was taken as the measured line width (unit: μm). The ratio of the measured value to the design line width of the photomask (10 μm) (measured value / design value) was calculated. This ratio (measured value / design value) is shown in Table 3 as the accuracy of the resist line width. The closer this value is to 1, the less the obtained resist line width deviates from the design value.

[0134] [Table 3] [Explanation of Symbols]

[0135] 1...Photosensitive element, 2...Support, 3, 32...Photosensitive resin layer, 4...Protective layer, 10...Conducting layer, 15...Insulating layer, 20...Mask, 30...Resist pattern, 40...Conducting pattern, 42...Plating layer, 50...Activating light.

Claims

[Claim 1] (A) a binder polymer, (B) a photopolymerizable compound having at least one ethylenically unsaturated bond, and (C) a photopolymerization initiator, The (C) photopolymerization initiator comprises an oxime ester-based photopolymerization initiator, A photosensitive resin composition in which the content of the oxime ester-based photopolymerization initiator is 0.3 parts by mass or more with respect to 100 parts by mass of the total of the binder polymer (A) and the photopolymerizable compound (B).

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