JP7327485B2 - Photosensitive resin composition, photosensitive element, method for forming resist pattern, and method for producing printed wiring board - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a photosensitive resin composition, a photosensitive element, a method for forming a resist pattern, and a method for manufacturing a printed wiring board.

In the field of manufacturing printed wiring boards, a photosensitive resin composition is used as a resist material for etching or plating, and a layer formed using a photosensitive resin composition on a support film (hereinafter referred to as " Photosensitive elements with a "photosensitive layer") are widely used.

A printed wiring board is manufactured using the above-described photosensitive element, for example, according to the following procedure. That is, first, the photosensitive layer of the photosensitive element is laminated on a circuit-forming substrate such as a copper-clad laminate. Next, the photosensitive layer is exposed through a mask film or the like to form a photocured portion. At this time, the support film is peeled off before or after the exposure. After that, 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 (resist pattern) of the photosensitive layer is stripped (removed).

In recent years, as the density of printed wiring boards has increased, the contact area between the circuit-forming substrate and the photosensitive layer, which is a resist, has become smaller as conductor patterns have become finer. Therefore, the photosensitive layer is required to have excellent properties in etching treatment or plating treatment, as well as excellent adhesion to circuit forming substrates and excellent resolution in forming a resist pattern.

For example, Patent Document 1 discloses a photosensitive resin composition having excellent sensitivity and resolution by using a specific sensitizing dye. Further, Patent Document 2 discloses a photosensitive resin composition excellent in sensitivity and resolution by using a specific alkali-soluble polymer and a compound having an ethylenic double bond.

JP 2009-003177 A JP 2013-061556 A

In order to improve production efficiency, each process is required to be shortened and shortened. For example, shortening of peeling time is demanded at the same time as resolution and the like are demanded. The photosensitive resin composition is required to form a resist pattern with high developability in the unexposed area and excellent resolution. It is required to be excellent in

The present disclosure provides a photosensitive resin composition having an excellent balance of developability, resolution and release properties, a photosensitive element using the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a printed wiring board. for the purpose.

The photosensitive resin composition according to the present disclosure contains a binder polymer having a structural unit derived from styrene or a styrene derivative, a photopolymerizable compound, and a photopolymerization initiator, and the acid value of the binder polymer is 165 to 195 mgKOH/g, and the photopolymerizable compound contains a (meth)acrylate having a phthalic acid skeleton.

The binder polymer may have 41 to 64% by mass of structural units derived from styrene or styrene derivatives. The weight average molecular weight of the binder polymer may range from 5,000 to 37,000.

The content of the (meth)acrylate having a phthalic acid skeleton may be 1 to 30 parts by mass with respect to 100 parts by mass as the total amount of the binder polymer and the photopolymerizable compound. Moreover, the photopolymerization initiator may include an acridine-based photopolymerization initiator.

A photosensitive element according to the present disclosure comprises a support and a photosensitive layer formed on the support, wherein the photosensitive layer contains the photosensitive resin composition described above.

The method for forming a resist pattern according to the present disclosure includes the steps of forming a photosensitive layer on a substrate using the above-described photosensitive resin composition or photosensitive element, and irradiating a predetermined portion of the photosensitive layer with an actinic ray. forming a photo-cured portion; and removing at least a portion of the photosensitive layer other than the photo-cured portion from the substrate.

A printed wiring board manufacturing method according to the present disclosure includes a step of etching or plating a substrate on which a resist pattern has been formed by the resist pattern forming method to form a conductor pattern. The printed wiring board manufacturing method may further include a step of removing the photocured portion after the etching treatment or the plating treatment.

According to the present disclosure, a photosensitive resin composition having an excellent balance of developability, resolution and peeling properties, a photosensitive element using the photosensitive resin composition, a method for forming a resist pattern, and a method for producing a printed wiring board are provided. can provide.

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

The present disclosure will be described in detail below. In this specification, a numerical range indicated using "to" indicates a range including the numerical values before and after "to" as the minimum and maximum values, respectively. In addition, in the numerical ranges described stepwise in this specification, the upper limit or lower limit of the numerical range at one stage may be replaced with the upper limit or lower limit of the numerical range at another stage. In the numerical ranges described herein, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.

As used herein, "(meth)acrylic acid" means at least one of "acrylic acid" and "methacrylic acid" corresponding thereto, and the same applies to other similar expressions such as (meth)acrylate.

As used herein, the term “solid content” refers to non-volatile content excluding volatile substances such as water and solvents contained in the photosensitive resin composition, and when the resin composition is dried, It also includes those that are liquid, syrup-like, and wax-like at room temperature around 25°C.

[Photosensitive resin composition]
The photosensitive resin composition according to this embodiment contains a binder polymer having a structural unit derived from styrene or a styrene derivative, a photopolymerizable compound, and a photopolymerization initiator. The binder polymer has an acid value of 165 to 195 mgKOH/g, and the photopolymerizable compound includes a phthalic acid compound. Each component used in the photosensitive resin composition of the present embodiment will be described in detail below.

((A) binder polymer)
(A) The binder polymer (hereinafter also referred to as "(A) component") has a structural unit derived from styrene or a styrene derivative, thereby improving the release properties of the photosensitive layer formed from the photosensitive resin composition. be able to. Component (A) can be produced, for example, by radically polymerizing a polymerizable monomer containing styrene or a styrene derivative.

Styrene derivatives are polymerizable compounds such as vinyltoluene, α-methylstyrene, etc., in which the hydrogen atom at the α-position or aromatic ring of styrene is substituted. The content of structural units derived from styrene or styrene derivatives in component (A) is 41 to 64% by mass, 41 to 60% by mass, 42 to 55% by mass, or 43% by mass, based on the total amount of component (A). It may be up to 50% by mass. When this content is 41% by mass or more, the resolution tends to be further improved, and when it is 64% by mass or less, it is possible to suppress the increase in peeled pieces during development, and the tendency is to suppress the lengthening of the time required for peeling. be.

The component (A) may have a carboxy group from the standpoint of alkali developability. The component (A) having a carboxy group can be produced, for example, by radically polymerizing a polymerizable monomer having a carboxy group and a polymerizable monomer containing styrene or a styrene derivative.

Examples of polymerizable monomers having a carboxy group include (meth)acrylic acid, α-bromoacrylic acid, α-chloroacrylic acid, β-furyl (meth)acrylic acid, β-styryl (meth)acrylic acid, Maleic acid, maleic anhydride, monomethyl maleate, monoethyl maleate, monoisopropyl maleate and other maleic acid monoesters, fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, and propiolic acid. mentioned. From the viewpoint of further improving alkali developability, the polymerizable monomer having a carboxy group may be (meth)acrylic acid or methacrylic acid.

From the viewpoint of improving alkali developability and alkali resistance in a well-balanced manner, the content of structural units derived from a polymerizable monomer having a carboxy group is 10 to 50% by mass based on the total amount of component (A). , 15 to 40% by weight, or 20 to 35% by weight. When the content is 10% by mass or more, the alkali developability tends to be improved, and when the content is 50% by mass or less, the alkali resistance tends to be excellent.

Component (A) further includes a structural unit derived from a polymerizable monomer other than styrene or a styrene derivative and a polymerizable monomer having a carboxy group (hereinafter also referred to as "(other polymerizable monomer")). Other polymerizable monomers include, for example, acrylamides such as diacetone acrylamide, acrylonitrile, vinyl alcohol ethers such as vinyl-n-butyl ether, (meth)acrylic acid alkyl esters, (meth) ) benzyl acrylate, (meth)acrylate tetrahydrofurfuryl ester, (meth)acrylate dimethylaminoethyl ester, (meth)acrylate diethylaminoethyl ester, (meth)acrylate glycidyl ester, 2,2,2-tri fluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, etc. Other polymerizable monomers may be used alone or in combination of two or more. can be done.

The component (A) may have a structural unit derived from a (meth)acrylic acid alkyl ester from the viewpoint of improving plasticity. Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and pentyl (meth)acrylate. Ester, (meth)acrylic acid hexyl ester, (meth)acrylic acid heptyl ester, (meth)acrylic acid octyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid nonyl ester, (meth)acrylic acid decyl ester esters, undecyl (meth)acrylate, and dodecyl (meth)acrylate.

The acid value of component (A) is 165 to 195 mgKOH/g, and from the viewpoint of further improving the balance between developability, resolution and peeling properties, it is 170 to 195 mgKOH/g, 175 to 193 mgKOH/g, or 180 to 190 mgKOH/g. g.

The weight average molecular weight (Mw) of component (A) may be 5,000 to 37,000, 8,000 to 36,000, 10,000 to 35,000, or 15,000 to 33,000. When the Mw of the component (A) is 5,000 or more, the developer resistance of the photocured portion tends to be excellent. Component (A) may have a degree of dispersion (weight average molecular weight/number average molecular weight) of 1.0 to 3.0, or 1.0 to 2.0. Resolution tends to improve as the degree of dispersion decreases.

The weight-average molecular weight and number-average molecular weight in this specification are values measured by gel permeation chromatography (GPC) and converted using standard polystyrene as a standard sample.

(A) Component can be used individually by 1 type or in combination of 2 or more types. As the component (A) when two or more are used in combination, for example, two or more binder polymers composed of different polymerizable monomers, two or more binder polymers having different Mw, and different dispersion degrees Two or more binder polymers are included.

The content of component (A) is 30 to 80 parts by mass, 40 to 75 parts by mass, 50 to 70 parts by mass, or 50 to It may be 60 parts by mass. If the content of component (A) is within this range, the strength of the photocured portion of the photosensitive layer will be better.

((B) photopolymerizable compound)
(B) The photopolymerizable compound (hereinafter also referred to as "(B) component") contains a (meth)acrylate having a phthalic acid skeleton, thereby improving the resolution of the resist pattern and the release properties after curing in a well-balanced manner. be able to.

(Meth)acrylates having a phthalic acid skeleton include, for example, γ-chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate, β-hydroxyethyl-β'-(meth)acryloyloxy Ethyl-o-phthalate, and β-hydroxypropyl-β'-(meth)acryloyloxyethyl-o-phthalate. γ-Chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate is commercially available as FA-MECH (Hitachi Chemical Co., Ltd.).

The content of the (meth)acrylate having a phthalic acid skeleton is 1 to 30 parts by mass, 2 to 25 parts by mass, 5 to 20 parts by mass, based on 100 parts by mass of the total amount of components (A) and (B). Alternatively, it may be 8 to 15 parts by mass. If the content of the (meth)acrylate having a phthalic acid skeleton is within this range, the peeling properties will be better.

The component (B) may further contain a photopolymerizable compound other than the (meth)acrylate having a phthalic acid skeleton (hereinafter also referred to as “another photopolymerizable compound”). As another photopolymerizable compound, a compound having an ethylenically unsaturated bond can be used. Other photopolymerizable compounds may be used singly or in combination of two or more.

The ethylenically unsaturated bond is not particularly limited as long as photopolymerization is possible. Examples of ethylenically unsaturated bonds include α,β-unsaturated carbonyl groups such as (meth)acryloyl groups. Examples of the photopolymerizable compound having an α,β-unsaturated carbonyl group include α,β-unsaturated carboxylic acid esters of polyhydric alcohols, bisphenol-type (meth)acrylates, and α,β-unsaturated glycidyl group-containing compounds. Saturated carboxylic acid adducts, (meth)acrylates having urethane bonds, nonylphenoxypolyethyleneoxyacrylates, and (meth)acrylic acid alkyl esters can be mentioned.

Examples of α,β-unsaturated carboxylic acid esters of polyhydric alcohols include polyethylene glycol di(meth)acrylate having 2 to 14 ethylene groups and polypropylene glycol di(meth)acrylate having 2 to 14 propylene groups. meth)acrylate, polyethylene-polypropylene glycol di(meth)acrylate having 2 to 14 ethylene groups and 2 to 14 propylene 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, tetramethylolmethane tetra (Meth)acrylates and (meth)acrylate compounds having a skeleton derived from dipentaerythritol or pentaerythritol. "EO-modified" means having a block structure of ethylene oxide (EO) groups, and "PO-modified" means having a block structure of propylene oxide (PO) groups.

The component (B) may contain polyalkylene glycol di(meth)acrylate from the viewpoint of improving the flexibility of the resist pattern. The polyalkylene glycol di(meth)acrylate may have at least one of EO and PO groups, or both EO and PO groups. In the polyalkylene glycol di(meth)acrylate having both EO groups and PO groups, the EO groups and PO groups may be present continuously in blocks or randomly. Also, the PO group may be either an oxy-n-propylene group or an oxyisopropylene group. In addition, in the (poly)oxyisopropylene group, the secondary carbon of the propylene group may be bonded to the oxygen atom, or the primary carbon may be bonded to the oxygen atom.

Examples of commercially available polyalkylene glycol di(meth)acrylates include FA-023M (manufactured by Hitachi Chemical Co., Ltd.), FA-024M (manufactured by Hitachi Chemical Co., Ltd.), and NK Ester HEMA-9P (Shin-Nakamura Chemical Co., Ltd. manufactured by the company).

The component (B) may contain a (meth)acrylate having a urethane bond from the viewpoint of improving the flexibility of the resist pattern. The (meth)acrylate having a urethane bond includes, for example, a (meth)acrylic monomer having an OH group at the β-position and a diisocyanate (isophorone diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, 1,6-hexa methylene diisocyanate, etc.), tris((meth)acryloxytetraethylene glycol isocyanate) hexamethylene isocyanurate, EO-modified urethane di(meth)acrylate, and EO, PO-modified urethane di(meth)acrylate.

Commercially available EO-modified urethane di(meth)acrylates include, for example, “UA-11” and “UA-21EB” (manufactured by Shin-Nakamura Chemical Co., Ltd.). Commercially available EO, PO-modified urethane di(meth)acrylates include, for example, "UA-13" (manufactured by Shin-Nakamura Chemical Co., Ltd.).

The component (B) may contain a (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol from the viewpoint of facilitating the formation of a thick resist pattern and improving resolution and adhesion in a well-balanced manner. The (meth)acrylate compound having a skeleton derived from dipentaerythritol or pentaerythritol preferably has four or more (meth)acryloyl groups, and is dipentaerythritol penta (meth) acrylate or dipentaerythritol hexa (meth) acrylate. may be

From the viewpoint of further improving resolution and release properties after curing, the component (B) may contain a bisphenol type (meth)acrylate, and among the bisphenol type (meth)acrylates, it may contain a bisphenol A type (meth)acrylate. . Bisphenol A type (meth)acrylates include, for example, 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane and 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. be done. Among them, 2,2-bis(4-((meth)acryloxypolyethoxy)phenyl)propane is preferable from the viewpoint of further improving the resolution and puttability.

Commercially available ones include, for example, 2,2-bis(4-((meth)acryloxydipropoxy)phenyl)propane, BPE-200 (Shin-Nakamura Chemical Co., Ltd.), 2,2- Bis(4-(methacryloxypentaethoxy)phenyl)propane includes BPE-500 (Shin-Nakamura Chemical Co., Ltd.) and FA-321M (Hitachi Chemical Co., Ltd.).

Examples of nonylphenoxypolyethyleneoxyacrylate include nonylphenoxytetraethyleneoxyacrylate, nonylphenoxypentaethyleneoxyacrylate, nonylphenoxyhexaethyleneoxyacrylate, nonylphenoxyheptaethyleneoxyacrylate, nonylphenoxyoctaethyleneoxyacrylate, nonylphenoxynonaethyleneoxy acrylates, nonylphenoxydecaethyleneoxy acrylate, and nonylphenoxyundecaethyleneoxy acrylate.

((C) photoinitiator)
(C) The photopolymerization initiator (hereinafter also referred to as "component (C)") is not particularly limited as long as it can polymerize the component (B). It can be selected as appropriate. From the viewpoint of improving pattern formability, substances that generate free radicals by actinic rays, such as acylphosphine oxides, oxime esters, aromatic ketones, quinones, alkylphenones, imidazoles, acridines, and phenylglycine and coumarin-based photopolymerization initiators.

The component (C) may contain an acridine-based photopolymerization initiator, a phenylglycine-based photopolymerization initiator, or an imidazole-based photopolymerization initiator in order to improve sensitivity and resolution in a well-balanced manner. (C) Component can be used individually by 1 type or in combination of 2 or more types.

Examples of acridine photopolymerization initiators include 9-phenylacridine, 9-(p-methylphenyl)acridine, 9-(m-methylphenyl)acridine, 9-(p-chlorophenyl)acridine, 9-(m- chlorophenyl)acridine, 9-aminoacridine, 9-dimethylaminoacridine, 9-diethylaminoacridine, 9-pentylaminoacridine, 1,2-bis(9-acridinyl)ethane, 1,4-bis(9-acridinyl)butane, 1,6-bis(9-acridinyl)hexane, 1,8-bis(9-acridinyl)octane, 1,10-bis(9-acridinyl)decane, 1,12-bis(9-acridinyl)dodecane, 1, Bis(9) such as 14-bis(9-acridinyl)tetradecane, 1,16-bis(9-acridinyl)hexadecane, 1,18-bis(9-acridinyl)octadecane, 1,20-bis(9-acridinyl)eicosane -acridinyl)alkanes, 1,3-bis(9-acridinyl)-2-oxapropane, 1,3-bis(9-acridinyl)-2-thiapropane, and 1,5-bis(9-acridinyl)-3- Thiapentane is mentioned.

Phenylglycine-based photopolymerization initiators include, for example, N-phenylglycine, N-methyl-N-phenylglycine, and N-ethyl-N-phenylglycine.

Examples of imidazole-based photopolymerization initiators include 2-(o-chlorophenyl)-4,5-diphenylbiimidazole, 2,2′,5-tris-(o-chlorophenyl)-4-(3,4-dimethoxy Phenyl)-4′,5′-diphenylbiimidazole, 2,4-bis-(o-chlorophenyl)-5-(3,4-dimethoxyphenyl)-diphenylbiimidazole, 2,4,5-tris-(o -chlorophenyl)-diphenylbiimidazole, 2-(o-chlorophenyl)-bis-4,5-(3,4-dimethoxyphenyl)-biimidazole, 2,2′-bis-(2-fluorophenyl)-4, 4′,5,5′-tetrakis-(3-methoxyphenyl)-biimidazole, 2,2′-bis-(2,3-difluoromethylphenyl)-4,4′,5,5′-tetrakis-( 3-methoxyphenyl)-biimidazole, 2,2′-bis-(2,4-difluorophenyl)-4,4′,5,5′-tetrakis-(3-methoxyphenyl)-biimidazole, and 2, 2'-bis-(2,5-difluorophenyl)-4,4',5,5'-tetrakis-(3-methoxyphenyl)-biimidazole.

The content of component (C) is 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, and 0.4 to 3 parts by mass based on 100 parts by mass of the total amount of components (A) and (B). , or 0.5 to 2 parts by mass. When the content of component (C) is 0.1 parts by mass or more, photosensitivity, resolution and adhesion tend to be improved, and when it is 10 parts by mass or less, resist pattern formability tends to be more excellent.

(other ingredients)
The photosensitive resin composition according to the present embodiment may optionally contain a dye, a photocoloring agent, a thermal coloring inhibitor, a plasticizer, a pigment, a filler, an antifoaming agent, a flame retardant, an adhesion imparting agent, and a leveling agent. Additives such as agents, release accelerators, antioxidants, fragrances, imaging agents, thermal cross-linking agents, and polymerization inhibitors may be further contained. These additives can be used singly or in combination of two or more.

Dyes include, for example, malachite green, victoria pure blue, brilliant green, and methyl violet. Photochromic agents include, for example, tribromophenylsulfone, leucocrystal violet, diphenylamine, benzylamine, triphenylamine, diethylaniline, and o-chloroaniline. Plasticizers include, for example, p-toluenesulfonamide.

The content of the additive is 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, or 0.1 to 3 parts by mass based on 100 parts by mass of the total amount of components (A) and (B). There may be.

The photosensitive resin composition is dissolved in a solvent such as methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N,N-dimethylformamide, propylene glycol monomethyl ether, or a mixed solvent thereof, if necessary. can be prepared as a solution with a solid content of about 30 to 60% by mass.

[Photosensitive element]
The photosensitive element of this embodiment comprises a support and a photosensitive layer formed on the support, and the photosensitive layer contains the photosensitive resin composition described above. When the photosensitive element of this embodiment is used, after the photosensitive layer is laminated on the substrate, exposure may be performed without peeling off the support (support film). A photosensitive element 1 according to the present embodiment includes a support 2 and a photosensitive layer 3 formed on the support 2 and derived from the photosensitive resin composition, as shown in a schematic cross-sectional view of an example thereof in FIG. and other layers such as a protective layer 4 provided as necessary.

(support)
Examples of the support include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyethylene-2,6-naphthalate (PEN), and polyolefin films such as polypropylene and polyethylene. Among them, a PET film may be used because it is easily available and has excellent handleability (in particular, heat resistance, heat shrinkage, and breaking strength) in the manufacturing process.

The haze of the support may be 0.01-1.0% or 0.01-0.5%. A haze of 0.01% or more tends to facilitate the production of the support itself, and a haze of 1.0% or less tends to reduce minute defects that may occur in the resist pattern. "Haze" means cloudiness. Haze in the present disclosure refers to a value measured using a commercially available cloudiness meter (turbidity meter) in accordance with the method specified in JIS K 7105. Haze can be measured with a commercially available turbidity meter such as NDH-5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

The thickness of the support may be 1-100 μm, 5-60 μm, 10-50 μm, 10-40 μm, 10-30 μm, or 10-25 μm. When the thickness of the support is 1 μm or more, it tends to be possible to suppress tearing of the support when the support is peeled off. Further, when the thickness of the support is 100 μm or less, it is possible to suppress deterioration in resolution when exposure is performed through the support.

(protective layer)
The photosensitive element may further comprise a protective layer if desired. As the protective layer, a film in which the adhesive strength between the photosensitive layer and the protective layer is smaller than the adhesive strength between the photosensitive layer and the support may be used. may be used. Specific examples include those that can be used as the support described above. From the standpoint of releasability from the photosensitive layer, it may be a polyethylene film. The thickness of the protective layer may be about 1 to 100 μm, depending on the application.

A photosensitive element can be manufactured, for example, as follows. That is, a solution (coating liquid) of a photosensitive resin composition is applied onto a support to form a coating layer, which is then dried to form a photosensitive layer. Then, the surface of the photosensitive layer opposite to the support is covered with a protective layer, thereby separating the support, the photosensitive layer formed on the support, and the protective layer laminated on the photosensitive layer. A photosensitive element is obtained comprising:

Application of the coating solution onto the support can be carried out by known methods such as roll coating, comma coating, gravure coating, air knife coating, die coating, bar coating and the like.

There are no particular restrictions on the drying of the coating layer as long as at least part of the organic solvent can be removed from the coating layer. For example, it may be carried out at 70 to 150° C. for about 5 to 30 minutes. After drying, the amount of solvent remaining in the photosensitive layer may be 2% by mass or less from the viewpoint of preventing diffusion of the solvent in subsequent steps.

The thickness of the photosensitive layer in the photosensitive element can be appropriately selected depending on the application, and the thickness after drying may be 1 to 100 μm, 1 to 50 μm, or 5 to 40 μm. When the thickness is 1 µm or more, industrial coating is facilitated and productivity is improved. Further, when the thickness is 100 μm or less, adhesion and resolution are improved.

The form of the photosensitive element is not particularly limited. For example, it may be in the form of a sheet, or may be in the form of a roll wound around a core. When wound into a roll, the film may be wound with the support film on the outside. Examples of the winding core include plastics such as polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, and ABS resin (acrylonitrile-butadiene-styrene copolymer).

An end face separator may be provided on the end face of the roll-shaped photosensitive element for protection of the end face, or a moisture-proof end face separator may be provided for edge fusion resistance. The photosensitive element may be packaged by wrapping it in a black sheet with low moisture permeability.

The photosensitive element can be suitably used, for example, in the method of forming a resist pattern, which will be described later. Above all, from the viewpoint of resolution, it is suitable for application to a manufacturing method in which a conductive pattern is formed by plating.

[Method of forming a resist pattern]
The method for forming a resist pattern of the present embodiment includes (i) a step of forming a photosensitive layer on a substrate using the photosensitive resin composition or the photosensitive element (photosensitive layer forming step); ii) a step of irradiating at least a portion (predetermined portion) of the photosensitive layer with actinic rays to form a photocured portion (exposure step); and (iii) at least a portion other than the photocured portion from the substrate. and a step of removing the (development step), and may include other steps as necessary. A resist pattern can be said to be a pattern of a photocured product of a photosensitive resin composition, or a relief pattern. The method of forming a resist pattern can also be said to be a method of manufacturing a substrate with a resist pattern.

((i) Photosensitive layer forming step)
As a method for forming a photosensitive layer on a substrate, for example, the photosensitive resin composition may be applied and dried, or after removing the protective layer from the photosensitive element, the photosensitive layer of the photosensitive element may be formed. It may be pressure-bonded to the substrate while being heated. When a photosensitive element is used, a laminate comprising a substrate, a photosensitive layer and a support, which are laminated in order, is obtained. Although the substrate is not particularly limited, a circuit forming substrate comprising an insulating layer and a conductor layer formed on the insulating layer, or a die pad (lead frame substrate) such as an alloy substrate is usually used.

When a photosensitive element is used, the photosensitive layer forming step is preferably carried out under reduced pressure from the viewpoint of adhesion and followability. Heating of the photosensitive layer and/or the substrate during compression may be performed at a temperature of 70 to 130.degree. Crimping may be performed at a pressure of approximately 0.1 to 1.0 MPa (approximately 1 to 10 kgf/cm ² ), but these conditions are appropriately selected as necessary. If the photosensitive layer is heated to 70 to 130° C., it is not necessary to preheat the substrate, but the substrate may be preheated in order to further improve adhesion and followability.

((ii) exposure step)
In the exposure step, at least a portion of the photosensitive layer formed on the substrate is irradiated with actinic rays, and the portion irradiated with actinic rays is photocured to form a latent image. In this case, when a support is present on the photosensitive layer, actinic rays can be irradiated through the support if the support is transparent to actinic rays. irradiates the photosensitive layer with an actinic ray after removing the support.

Examples of the exposure method include a method of irradiating actinic rays 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. Moreover, you may employ|adopt the method of irradiating an actinic ray imagewise by direct drawing exposure methods, such as LDI (Laser Direct Imaging) exposure method and DLP (Digital Light Processing) exposure method.

As a light source for actinic rays, known light sources can be used. A material that effectively emits ultraviolet rays and visible light is used.

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

When a support is present on the photosensitive layer, after removing the support, areas other than the photocured areas (which can be called unexposed areas) are removed (developed). Developing methods include wet development and dry development, and wet development is widely used.

In the case of wet development, development is performed by a known developing method using a developer corresponding to the photosensitive resin composition. Examples of the developing method include methods using a dip method, a paddle method, a spray method, brushing, slapping, scrubbing, rocking immersion, etc. From the viewpoint of improving resolution, a high-pressure spray method may be used. . Development may be performed by combining two or more of these methods.

The composition of the developer is appropriately selected according to the composition of the photosensitive resin composition. The developer includes, for example, an alkaline aqueous solution and an organic solvent developer.

From the standpoint of safety, stability, and good operability, an alkaline aqueous solution may be used as the developer. Examples of the base of the alkaline aqueous solution include alkali hydroxides such as lithium, sodium or potassium hydroxide; alkali carbonates such as lithium, sodium, potassium or ammonium carbonates or bicarbonates; potassium phosphate, sodium phosphate and the like. alkali metal phosphate; alkali metal pyrophosphate such as sodium pyrophosphate and potassium pyrophosphate; borax, sodium metasilicate, tetramethylammonium hydroxide, ethanolamine, ethylenediamine, diethylenetriamine, 2-amino-2-hydroxymethyl- 1,3-propanediol, 1,3-diaminopropanol-2, morpholine and the like are used.

Alkaline aqueous solutions used for development include dilute solutions of 0.1 to 5% by mass sodium carbonate, dilute solutions of 0.1 to 5% by mass potassium carbonate, dilute solutions of 0.1 to 5% by mass sodium hydroxide, and 0.1% to 5% by mass. A dilute solution of 1 to 5 mass % sodium tetraborate or the like can be used. 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, a small amount of organic solvent for promoting development, and the like.

Organic solvents used in the alkaline aqueous solution include, for example, 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 may be mentioned.

Examples of organic solvents used in organic solvent developers include 1,1,1-trichloroethane, N-methylpyrrolidone, N,N-dimethylformamide, cyclohexanone, methylisobutylketone and γ-butyrolactone. In order to prevent ignition, water may be added to these organic solvents in a range of 1 to 20% by mass to prepare an organic solvent developer.

In the method of forming a resist pattern in the present embodiment, after removing the uncured portion in the development step, heating at about 60 to 250° C. or exposure at about 0.2 to 10 J/cm ² is performed as necessary. may include a step of further hardening the resist pattern.

[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 is formed by the above method of forming a resist pattern to form a conductor pattern. It may be configured to include other processes such as a pattern removing process.

In plating, a conductor layer provided on a substrate is plated using a resist pattern formed on the substrate as a mask. After plating, the resist may be removed by removing the resist pattern, which will be described later, and the conductor layer covered with the resist may be etched to form the conductor pattern. The method of plating treatment may be electrolytic plating treatment, electroless plating treatment, or electroless plating treatment.

On the other hand, in the etching process, a conductor layer provided on the substrate is removed by etching using a resist pattern formed on the substrate as a mask to form a conductor pattern. The etching method is appropriately selected according to the conductor layer to be removed. Examples of the etching solution include cupric chloride solution, ferric chloride solution, alkaline etching solution, hydrogen peroxide-based etching solution, and the like.

After etching or plating, the resist pattern on the substrate may be removed. The resist pattern can be removed, for example, with a stronger alkaline aqueous solution than the alkaline aqueous solution used in the developing step. As the strong alkaline aqueous solution, for example, a 1 to 10% by mass sodium hydroxide aqueous solution, a 1 to 10% by mass potassium hydroxide aqueous solution, or the like is used.

When the resist pattern is removed after the plating treatment, the desired printed wiring board can be manufactured by further etching the conductor layer covered with the resist by etching treatment to form the conductor pattern. The etching method at this time is appropriately selected according to the conductor layer to be removed. For example, the etchant described above can be applied.

The printed wiring board manufacturing method according to the present embodiment can be applied not only to manufacturing single-layer printed wiring boards, but also to manufacturing multilayer printed wiring boards, and also to manufacturing printed wiring boards having small-diameter through-holes. It is possible.

EXAMPLES The purpose and advantages of the present embodiment will be described in more detail below based on examples and comparative examples, but the present embodiment is not limited to the following examples.

(Binder polymer (A-1))
A solution a was prepared by mixing 24 g of methacrylic acid, 26 g of methyl methacrylate, 35 g of styrene, 0.02 g of 4-methoxyphenol, and 0.7 g of azobisisobutyronitrile. Also, 9 g of propylene glycol monomethyl ether, 7.6 g of toluene, and 0.14 g of azobisisobutyronitrile were mixed to prepare solution b. Furthermore, 4.5 g of propylene glycol monomethyl ether, 7.6 g of toluene, and 0.5 g of azobisisobutyronitrile were mixed to prepare solution c.

48 g of propylene glycol monomethyl ether, 40 g of toluene, 5 g of methacrylic acid, and 10 g of styrene were charged into a flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen gas introduction tube, and nitrogen gas was blown into the flask. While stirring at 80° C. for 30 minutes, a mixed solution was obtained.

After the above solution a was added dropwise to the mixed liquid in the flask over 4 hours, the mixture was stirred at 80° C. for 2 hours. Next, the above solution b was added dropwise to the solution in the flask, and the mixture was stirred at 80°C for 2 hours. Further, the solution in the flask was heated to 95° C. over 1 hour while stirring was continued, and then the above solution c was added dropwise over 10 minutes, followed by stirring at 95° C. for 2 hours for reaction. After cooling the reaction solution to 50° C., methanol was added to obtain a solution of binder polymer (A-1). The non-volatile content (solid content) of the binder polymer (A-1) was 47.7% by mass.

(Binder Polymers (A-2) and (A-3))
Binder polymer (A-2) and (A-2) and ( A-3) solution was obtained.

(Weight average molecular weight)
120 mg of the binder polymer solution was collected and dissolved in 5 mL of THF to prepare a sample for Mw measurement. Mw was derived by measuring by gel permeation chromatography (GPC) and converting using a standard polystyrene calibration curve. The conditions of GPC are shown below.

(GPC conditions)
Pump: Hitachi L-6000 type (manufactured by Hitachi, Ltd.)
Column: Gelpack GL-R420, Gelpack GL-R430 and Gelpack GL-R440 (manufactured by Hitachi Chemical Co., Ltd., column specifications: 10.7 mmφ × 300 mm)
Eluent: Tetrahydrofuran (hereinafter also referred to as "THF")
Measurement temperature: 40°C
Injection volume: 200 μL
Pressure: 49 kgf/cm ² (4.8 MPa)
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd.)

(acid number)
A suitable amount of a phenolphthalein solution is added as an indicator to a solution prepared by adding a mixed solvent (mass ratio: toluene/methanol = 70/30) to about 1 g of the binder polymer, and titration is performed with a 0.1N potassium hydroxide aqueous solution. Thus, the acid value of the binder polymer was measured.

[Photosensitive resin composition]
The photosensitive resin compositions of Examples and Comparative Examples were prepared by mixing each component in the amounts (parts by mass) shown in Table 2 and solvents (methanol, toluene, acetone). The blending amount of the binder polymer shown in Table 2 is the mass of non-volatile matter (solid content).

Details of each component shown in Table 2 are as follows.
((B) photopolymerizable compound)
FA-321M: 2,2-bis(4-(methacryloxypentaethoxy)phenyl)propane (Hitachi Chemical Co., Ltd.)
M2200: Ethoxylated bisphenol A dimethacrylate (modified with EO average of 20 mol) (manufactured by Miwon)
BPE-200: Ethoxylated bisphenol A dimethacrylate (modified with EO average 4 mol) (Shin-Nakamura Chemical Industry Co., Ltd.)
FA-MECH: γ-chloro-β-hydroxypropyl-β'-methacryloyloxyethyl-o-phthalate (Hitachi Chemical Co., Ltd.)
((C) photoinitiator)
9-PA: 9-phenylacridine (Changzhou Power Electronics New Materials Co., Ltd.)
N-PG: N-phenylglycine (Changzhou Power Electronics New Materials Co., Ltd.)
(Photochromic agent)
LCV: Leuco Crystal Violet (Yamada Chemical Industry Co., Ltd.)
TPS: Tribromophenyl sulfone (Changzhou Power Electronics New Materials Co., Ltd.)
(Adherence imparting agent)
SF-808H: a mixture of carboxybenzotriazole, 5-amino-1H-tetrazole and methoxypropanol (Sanwa Kasei Co., Ltd.)
(dye)
MKG: Malachite Green (Osaka Organic Chemical Industry Co., Ltd.)

[Photosensitive element]
The solution of the photosensitive resin composition is applied onto a polyethylene terephthalate (PET) film (Teijin Film Solution Co., Ltd., trade name "G2J") (support) with a thickness of 16 µm, and dried by hot air convection at 75°C and 125°C. They were dried in order in a vessel to form a photosensitive layer having a thickness of 25 μm after drying. A polypropylene film (manufactured by Tamapoly Co., Ltd., product name "NF-13") (protective layer) is laminated on the photosensitive layer, and a photosensitive element in which a support, a photosensitive layer, and a protective layer are laminated in this order is prepared. Obtained.

(Laminate)
A copper clad laminate (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-67") in which copper foil (thickness: 35 μm) is laminated on both sides of a glass fiber reinforced epoxy resin layer is washed with water, acid washed, and washed with water. Dried in stream. The copper clad laminate was then heated to 80° C. to laminate the photosensitive element on the copper surface of the copper clad laminate. The lamination was carried out using a heat roll at 110° C. while removing the protective layer at a pressing pressure of 0.4 MPa on the substrate and a roll speed of 1.0 m/min. Thus, a laminate was obtained in which the copper-clad laminate, the photosensitive layer, and the support were laminated in this order.

(light sensitivity)
On the support of the laminate, a Hitachi 41-step tablet as a negative mask having a density range of 0.00 to 2.00, a density step of 0.05, a tablet size of 20 mm x 187 mm, and each step size of 3 mm x 12 mm. (manufactured by Hitachi Chemical Co., Ltd.) was placed. Then, the photosensitive layer was exposed with a predetermined amount of energy using a DLP exposure machine (manufactured by Hitachi Via Mechanics Co., Ltd., product name "DE-1UH") with a wavelength of 405 nm using a semiconductor laser as a light source.

After exposure, the support was peeled off, and a 1% by weight sodium carbonate aqueous solution at 30° C. was sprayed for twice the shortest development time (shortest time for removing the unexposed portion) to remove the unexposed portion (development process). After the development treatment, the amount of energy (mJ/cm ² ) at which the step tablet of the photocured film formed on the substrate becomes 15.0 steps was determined, and the photosensitivity of the photosensitive resin composition was evaluated. A smaller value indicates a higher photosensitivity.

(resolution)
On the support of the laminate, a glass chrome type photo tool as a negative for resolution evaluation (resolution negative: having a wiring pattern with a line width/space width of x/x (x: 1 to 30, unit: μm)) was used, and the amount of energy was such that the number of steps remaining after development of the Hitachi 41-step tablet was 17.0. After exposure, the photosensitive layer was developed in the same manner as in the photosensitivity evaluation.

Evaluate the resolution from the smallest space width value of the resist pattern formed after the development processing, in which the space portion (unexposed portion) is cleanly removed and the line portion (exposed portion) is formed without meandering or chipping. did. A smaller numerical value means better resolution and adhesion.

(Peeling property)
The photosensitive layer of the laminate was exposed using a drawing pattern that forms a cured film of 40 mm×50 mm. After the exposure, the support was peeled off, and a test piece having a cured film of 40 mm×50 mm formed on the substrate was prepared by performing the same development treatment as in the photosensitivity evaluation.

After leaving the test piece at room temperature for a whole day and night, the test piece was immersed in a 3.0% by mass sodium hydroxide aqueous solution at 50° C., and the time (seconds) until the cured film was completely peeled off from the substrate was measured. Also, the size of the peeled pieces was visually observed. A shorter peeling time and a smaller peeled piece size indicate better peeling properties.

DESCRIPTION OF SYMBOLS 1... Photosensitive element, 2... Support, 3... Photosensitive layer, 4... Protective layer.

Claims (7)

Containing a binder polymer having a structural unit derived from styrene or a styrene derivative, a photopolymerizable compound, and a photopolymerization initiator,
The binder polymer has 41 to 64% by mass of structural units derived from the styrene or styrene derivative,
The acid value of the binder polymer is 180 to 195 mgKOH/g,
The binder polymer has a weight average molecular weight of 5000 to 36000,
A photosensitive resin composition, wherein the photopolymerizable compound contains a (meth)acrylate having a phthalic acid skeleton. The photosensitive resin according to claim 1 , wherein the content of the (meth)acrylate having a phthalic acid skeleton is 1 to 30 parts by mass with respect to 100 parts by mass as the total amount of the binder polymer and the photopolymerizable compound. Composition. The photosensitive resin composition according to claim 1 or 2 , wherein the photopolymerization initiator contains an acridine-based photopolymerization initiator. comprising a support and a photosensitive layer formed on the support;
A photosensitive element, wherein the photosensitive layer comprises the photosensitive resin composition according to any one of claims 1 to 3 . forming a photosensitive layer on a substrate using the photosensitive resin composition according to any one of claims 1 to 3 or the photosensitive element according to claim 4 ;
a step of irradiating a predetermined portion of the photosensitive layer with an actinic ray to form a photocured portion;
removing at least a portion of the photosensitive layer other than the photocured portion from the substrate;
A method of forming a resist pattern, comprising: A method of manufacturing a printed wiring board, comprising the step of etching or plating a substrate on which a resist pattern has been formed by the method of forming a resist pattern according to claim 5 to form a conductor pattern. 7. The method of manufacturing a printed wiring board according to claim 6 , further comprising the step of removing said photocured portion after said etching treatment or plating treatment.

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