JP2022124854A - Photosensitive resin composition and plating method - Google Patents

Abstract

To provide a photosensitive resin composition in which fine lines and dots are stably held on a base material and a non-exposure part of a photosensitive resin layer can be completely removed from the substrate by a developer in a step of forming a resist pattern and a plating step, and a plating method using the photosensitive resin composition.SOLUTION: There are provided a photosensitive resin composition which contains (A) an alkali-soluble resin, (B) a photopolymerization initiator and (C) a methacrylate monomer, and contains specific contents of (C1) ethylene oxide-modified dimethacrylate represented by specific formula, (C2) ethylene oxide-modified bisphenol type A dimethacrylate (compound which is represented by general formula (ii) and m+n=5-16) and (C3) ethylene oxide-modified bisphenol type A dimethacrylate (compound represented by general formula (ii) and m+n=3-4), as (C) the methacrylate monomer; and a plating method using the photosensitive resin composition.SELECTED DRAWING: None

Description

The present invention relates to a photosensitive resin composition and a plating method using the photosensitive resin composition.

2. Description of the Related Art In recent years, along with the miniaturization and weight reduction of electronic devices, miniaturization of patterns in printed wiring boards, metal masks and the like has been promoted. Therefore, in the production of a conductive circuit of a printed wiring board or the production of a metal mask, a metal layer is produced by a (semi)additive method using a photosensitive resin composition and electroplating.

For example, in the semi-additive method for printed wiring boards, first, a thin electroless plated layer is formed on the surface of an insulating resin such as glass epoxy resin by electroless plating, and then a photosensitive resin composition is added to the surface of the copper layer. A photosensitive resin layer is formed, then exposed and developed to form a resist pattern, then electroplated to form a thick electrolytic plated layer, then the resist pattern is peeled off, and the electroless plated layer that appears after peeling. is a method of etching (see, for example, Patent Document 1).

Further, for example, as a method for manufacturing a metal mask, a first step of forming a photosensitive resin layer containing a photosensitive resin composition having a predetermined thickness on a substrate, and an opening of the metal mask on the photosensitive resin layer. A second step of pattern exposure according to the above, a third step of developing to remove only the unexposed portion of the photosensitive resin layer to prepare a resist pattern, and exposing the substrate, and the substrate obtained by this third step. After performing a fourth step of forming a metal mask material layer on the exposed portion by electroplating, a fifth step of removing the remaining photosensitive resin layer and a sixth step of separating the metal mask material layer from the substrate are performed. There is a manufacturing method (see, for example, Patent Document 2).

In these methods, a narrow-pitch resist pattern is formed, and electrolytic plating is applied between the narrow spaces to form a thick metal layer that will become an electrolytic plating layer or a metal mask material layer. However, as the width of the resist pattern becomes narrower, meandering and peeling of the resist pattern tend to occur due to swelling of the photosensitive resin layer in the process of resist pattern formation by development and plating.

In order to solve such problems due to swelling of the photosensitive resin layer, photosensitive resin compositions having a small volume expansion coefficient in a developer and a low expansion rate have been proposed (see, for example, Patent Documents 3 to 8). ). By reducing the solubility of the photosensitive resin layer in the developer, fine lines and dots can be easily held on the substrate without meandering or deformation after development. In Patent Documents 3 to 8, the hydrophobicity of the binder polymer and monomer is adjusted to suppress the swelling of the photosensitive resin layer after exposure due to the developer, and to increase the adhesion of the photosensitive resin layer after exposure to the substrate. As a result, an improvement in resolution is achieved.

However, when the hydrophilicity of the alkali-soluble resin or monomer is lowered, the unexposed portion of the photosensitive resin layer becomes difficult to completely dissolve in the developer, and the unexposed portion of the photosensitive resin layer becomes difficult to dissolve in the narrow space after development. There is a problem that a residue tends to be generated, and a problem that the non-exposed portion remains on the substrate in the form of a thin film, which hinders the growth of the plating. Therefore, the photosensitivity is compatible with the characteristics of being able to form a resist pattern of fine lines and dots and maintaining the resist pattern on the substrate, as well as the characteristics of being able to completely remove the unexposed portions of the photosensitive resin layer with a developer. What is desired is a resin composition.

JP 2004-101617 A JP-A-4-166844 JP 2007-298972 A JP 2014-134815 A Japanese Patent No. 5679080 JP 2016-070978 A International Publication No. 2018/159629 Pamphlet Japanese Patent No. 6750088

An object of the present invention is to stably hold fine lines and dots on a base material in a process of forming a resist pattern and a plating process, and to completely remove the non-exposed part of the photosensitive resin layer from the substrate with a developer. It is an object of the present invention to provide a photosensitive resin composition which can be easily removed and a plating method using the photosensitive resin composition.

As a result of intensive studies to solve the above problems, the following means were found.

<1> (A) an alkali-soluble resin, (B) a photopolymerization initiator and (C) a methacrylate monomer,
(C) As methacrylate monomers, (C1) ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l = 16 to 30), (C2) ethylene oxide-modified bisphenol A-type dimethacrylate (general formula ( ii) and m+n=5 to 16) and (C3) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) and m+n=3 to 4),
(C) The content of (C1) ethylene oxide-modified dimethacrylate (a compound represented by the general formula (i) where l = 16 to 30) is 10 to 20 mass% with respect to the total amount of methacrylate monomer, C2) The content of ethylene oxide-modified bisphenol A type dimethacrylate (compound represented by general formula (ii) where m+n = 5 to 16) is 50 to 70% by mass, and (C3) ethylene oxide-modified bisphenol A type A photosensitive resin composition containing 15 to 35% by mass of dimethacrylate (compound represented by formula (ii) where m+n=3 to 4).

<2> The step of forming a photosensitive resin layer containing the photosensitive resin composition of the above <1> on a substrate, the step of performing pattern exposure to cure the exposed portion, and the photosensitive resin layer by performing development. removing the non-exposed portion of to form a resist pattern containing a cured photosensitive resin layer, removing the non-exposed portion of the photosensitive resin layer and plating the exposed base material, a plating method .

With the photosensitive resin composition of the present invention, fine lines and dots are stably retained on the substrate in the process of forming a resist pattern and the plating process, and the non-exposed portion of the photosensitive resin layer is exposed to the developer. It can be completely removed from the top.

The photosensitive resin composition and plating method of the present invention are described in detail below. In the specification, they may be abbreviated as follows.
(A): (A) alkali-soluble resin (B): (B) photopolymerization initiator (C): (C) methacrylate monomer (C1): (C1) ethylene oxide-modified dimethacrylate (represented by general formula (i) and l=16-30)
(C2): (C2) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n=5 to 16)
(C3): (C3) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n=3 to 4)

In the (A) alkali-soluble resin according to the present invention, the term “alkali-soluble” means that the film thickness of the alkali-soluble resin (A) is 0.5% when immersed in a 1% by mass sodium carbonate aqueous solution at 25° C. for 10 minutes. 01 μm or more dissolved. Specifically, (A) the alkali-soluble resin is a resin containing an acidic group, and examples thereof include resins having an acid value of 40 mgKOH/g or more. Specific examples of acidic groups include carboxyl groups, phenolic hydroxyl groups, sulfonic acid groups, and phosphoric acid groups.

Examples of (A) alkali-soluble resins include organic polymers such as (meth)acrylic resins, styrene resins, epoxy resins, amide resins, amide epoxy resins, alkyd resins, and phenol resins. . These may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, it is preferable to use (meth)acrylic resins. The (meth)acrylic resin may be a (meth)acrylic polymer obtained by copolymerizing (meth)acrylate as a main component with an ethylenically unsaturated carboxylic acid. Further, monomers having other copolymerizable ethylenically unsaturated groups may be copolymerized.

Examples of the (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate acrylates, lauryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(diethylamino)ethyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate ) acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate and the like.

As the ethylenically unsaturated carboxylic acid, monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid are preferably used, and dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and their anhydrides and half esters are preferably used. can also be used. Among these, acrylic acid and methacrylic acid are particularly preferred.

Other copolymerizable monomers having an ethylenically unsaturated group include, for example, styrene, α-methylstyrene, 4-methylstyrene, 3-methylstyrene, 2-methylstyrene, 4-ethylstyrene, 3-ethyl Styrene, 2-ethylstyrene, 4-methoxystyrene, 3-methoxystyrene, 2-methoxystyrene, 4-ethoxystyrene, 3-ethoxystyrene, 2-ethoxystyrene, 4-chlorostyrene, 3-chlorostyrene, 2-chloro Styrene, 4-bromostyrene, 3-bromostyrene, 2-bromostyrene, (meth)acrylonitrile, (meth)acrylamide, diacetoneacrylamide, vinyl acetate, vinyl-n-butyl ether and the like.

(A) The acid value of the alkali-soluble resin affects development speed, resist stripping speed, exposure sensitivity, softness of the photosensitive resin layer, adhesion between the photosensitive resin layer and the substrate, and the like. (A) The acid value of the alkali-soluble resin is preferably 40 to 500 mgKOH/g, more preferably 100 to 300 mgKOH/g. When the acid value is less than 40 mgKOH/g, development time tends to be long, while when it exceeds 500 mgKOH/g, the adhesion between the photosensitive resin layer and the substrate may deteriorate. The acid value is a value measured according to JIS K2501:2003.

The weight average molecular weight of (A) the alkali-soluble resin is preferably 5,000 to 50,000, more preferably 10,000 to 40,000. (A) If the weight average molecular weight of the alkali-soluble resin is less than 5,000, it may be difficult to form the photosensitive resin composition before curing into a film. On the other hand, if the mass-average molecular weight of (A) the alkali-soluble resin exceeds 50,000, the solubility in the developer deteriorates, and the unexposed portion of the photosensitive resin layer tends to remain in the form of a thin film on the substrate after development. Tend.

(B) Photopolymerization initiators include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2- Aromatic ketones such as morpholinopropan-1-one; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone , 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethylanthraquinone, etc. quinones; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether; benzoin compounds such as benzoin, methylbenzoin, ethylbenzoin; benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2- methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4- [4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4 Alkylphenones such as -(4-morpholinyl)phenyl]-1-butanone; Acylphos such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide Fin oxides; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(o-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H -carbazol-3-yl]-, 1-(o-acetyloxime) and other oxime esters; 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4 ,5-bis(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer , 2-(p-methoxy 2,4,5-triarylimidazole dimers such as siphenyl)-4,5-diphenylimidazole dimer; acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; ; N-phenylglycine, N-phenylglycine derivatives; coumarin compounds; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, Benzophenone compounds such as 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone, 4,4′-bis(dimethylamino)benzophenone, 4,4′-bis(diethylamino)benzophenone, etc. Examples include benzophenone compounds. The substituents of the aryl groups of the two 2,4,5-triarylimidazoles in the 2,4,5-triarylimidazole dimer may be the same to give a symmetrical compound, or they may be different. Asymmetric compounds may be provided. A thioxanthone-based compound and a tertiary amine compound may also be combined, such as a combination of diethylthioxanthone and dimethylaminobenzoic acid. These are used alone or in combination of two or more. Among them, 2,4,5-triarylimidazole dimer is highly sensitive and can be preferably used, and 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer can also be usefully used.

The photosensitive resin composition of the present invention includes (C) ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l = 16 to 30), (C2) ethylene oxide-modified dimethacrylate as (C) methacrylate monomer. Bisphenol A type dimethacrylate (compound represented by general formula (ii) where m + n = 5 to 16) and (C3) ethylene oxide-modified bisphenol A type dimethacrylate (compound represented by general formula (ii) where m + n = 3 to 4), and the content of (C1) ethylene oxide-modified dimethacrylate (compound represented by general formula (i) and l = 16 to 30) relative to the total amount of (C) methacrylate monomer (C2) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m + n = 5 to 16) content is 50 to 70% by mass, (C3) The content of (C3) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n = 3 to 4) is 15 to 35% by mass, thereby forming a resist pattern. The non-exposed portions of the photosensitive resin layer can be completely removed with a developer while maintaining the characteristics of being able to form a resist pattern of fine lines and dots on the base material without meandering or deformation in the forming process and plating process. The effect of not inhibiting plating formation can be achieved.

If l in (C1) is less than 16, the adhesiveness between the cured photosensitive resin layer and the substrate is reduced, and if l is greater than 30, the photosensitive resin layer tends to swell during development. A fine resist pattern cannot be formed. Therefore, l in (C1) is 16-30, more preferably 20-28, still more preferably 22-26.

When m + n in (C2) is less than 5, the unexposed portion of the photosensitive resin layer tends to remain as a thin film on the substrate surface after development. The layer tends to swell, making it impossible to form a fine resist pattern. Therefore, m+n in (C2) is 5-16, more preferably 7-14, and still more preferably 9-12.

When m + n in (C3) is less than 3, the unexposed portion of the photosensitive resin layer tends to remain in the form of a thin film on the substrate surface after development. The layer tends to swell, making it impossible to form a fine resist pattern. Therefore, m+n in (C2) is 3-4, more preferably 4.

(C) The methacrylate monomer may contain compounds other than (C1), (C2) and (C3). Examples of (C) methacrylate monomers other than (C1), (C2), and (C3) include compounds having one or more methacryloyl groups.

Compounds having one methacryloyl group include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl, isobutyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl Methacrylate, benzyl methacrylate, isomyristyl methacrylate, stearyl methacrylate, nonylphenoxy polyethylene glycol methacrylate (one or more ethoxy groups), 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, glycidyl methacrylate, lauryl methacrylate, tetrahydrofurfuryl methacrylate, 2- (Dimethylamino) ethyl methacrylate, 2-(diethylamino) ethyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, glycerin monomethacrylate, methoxypolyethylene glycol methacrylate (number of ethoxy groups is 2 to 30), phenoxy polyethylene glycol methacrylate (2 to 30 ethoxy groups), methoxy polypropylene glycol methacrylate (2 to 30 propoxy groups), phenoxy polypropylene glycol methacrylate (2 to 30 propoxy groups), 2-methacryloyloxyethyl succinate, 2-hydroxy-3-phenoxypropyl methacrylate, ethoxylated o-phenylphenol methacrylate and the like.

Moreover, as the compound having two methacryloyl groups in the (C) methacrylate monomer, for example, a compound obtained by reacting a polyhydric alcohol with two acrylic acids can be mentioned. Also, for example, ethylene glycol dimethacrylate, ethylene oxide-modified dimethacrylate (having 2 to 15 and 31 to 50 propoxy groups), propylene glycol dimethacrylate, polypropylene glycol dimethacrylate (having 2 to 30 propoxy groups), polytetramethylene glycol. Dimethacrylate, neopentyl glycol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,9-nonanediol dimethacrylate, di Methyloltricyclodecane dimethacrylate, ethylene oxide-modified bisphenol A type dimethacrylate (having 1 to 2 and 17 to 30 ethoxy groups), dimethacrylate of propylene oxide adduct of bisphenol A (having 2 to 40 propoxy groups), bisphenol A dimethacrylate of ethylene oxide and propylene oxide adducts (sum of ethoxy group and propoxy group is 2 to 40), neopentylglycol hydroxypivalate dimethacrylate, 9,9-bis[4-(2-methacryloyloxyester)phenyl ] fluoresin, tricyclodecanedimethanol dimethacrylate and the like.

Further, examples of the (C) methacrylate monomer compound having three or more methacryloyl groups include a compound obtained by reacting a polyhydric alcohol with acrylic acid. Further, for example, trimethylolpropane trimethacrylate, ditrimethylolpropane tetramethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, ethylene oxide-modified pentaerythritol trimethacrylate, trimethylolpropane trimethacrylate, glycidyl ether trimethacrylate, ethylene oxide-modified isocyanuric acid trimethacrylate, ε-caprolactone-modified tris-(2-methacryloxyethyl) isocyanurate, glycerin trimethacrylate, ethylene oxide-modified glycerin trimethacrylate, ethylene oxide-modified pentaerythritol tetramethacrylate, and the like. be done.

The content of (C1) is 10 to 20% by mass, more preferably 15 to 18% by mass, based on the total amount of (C) methacrylate monomer. If the content is less than 10% by mass, the adhesiveness between the cured photosensitive resin layer and the substrate is reduced, and fine lines and dots are peeled off by development. The photosensitive resin layer swells at , causing meandering and deformation of fine lines and dots.

The content of (C2) is 50 to 70% by mass, more preferably 55 to 65% by mass, based on the total amount of (C) methacrylate monomer. If the content is less than 50% by mass, the elution of the non-exposed portions of the photosensitive resin layer into the developer is reduced, fine holes and spaces cannot be removed, and the non-exposed portions of the photosensitive resin layer are not removed after development. remains in the form of a thin film on the surface of the base material, and if the content is greater than 70% by mass, the adhesion between the photosensitive resin layer and the base material decreases, and the photosensitive resin layer swells during development. Meandering and peeling occur in fine lines and dots.

The content of (C3) is preferably 15 to 35% by mass, more preferably 17 to 25% by mass, based on the total amount of (C) methacrylate monomer. If the content is less than 15% by mass, the photosensitive resin layer swells during development, causing meandering and peeling of fine lines and dots during development. The non-exposed portion of the photosensitive resin layer remains in the form of a thin film on the substrate surface.

The photosensitive resin composition of the invention may contain an acrylate monomer. The acrylate monomer is a compound obtained by replacing the methacryloyl group of the methacrylate monomer (C) with an acryloyl group. In the present invention, the content of the acrylate monomer is preferably 0 to 10% by mass with respect to the total amount of the (C) methacrylate monomer. If the content of the acrylate monomer exceeds 10% by mass, the cured photosensitive resin layer tends to swell with the developing solution during development, which may cause meandering and peeling of fine lines and dots.

The photosensitive resin composition of the present invention may optionally contain components other than the above (A) to (C). Such components include solvents, photopolymerization inhibitors, thermal polymerization inhibitors, plasticizers, colorants (dyes, pigments), photocoloring agents, photocolor reducing agents, photocurable resins, anti-thermal coloration agents, fillers. , antifoaming agents, flame retardants, adhesion imparting agents, leveling agents, peeling accelerators, antioxidants, fragrances, heat curing agents, water repellents and oil repellents, each about 0.01 to 20% by mass. can contain. These components can be used individually by 1 type or in combination of 2 or more types.

In the photosensitive resin composition of the present invention, the content of (A) is preferably 39.9 to 75% by mass with respect to the total amount of (A), (B) and (C), and 45 to 60% by mass. % by mass is more preferred. If the content of (A) is less than 39.9% by mass, the film properties may deteriorate or the developability may deteriorate. If the content of (A) exceeds 75% by mass, the resolution of the resist pattern may deteriorate.

The content of (B) is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, relative to the total amount of (A), (B) and (C). . If the content of (B) is less than 0.1% by mass, the photopolymerizability tends to be insufficient. On the other hand, if it exceeds 10% by mass, the absorption on the surface of the photosensitive resin layer increases during exposure, and the photocrosslinking inside the photosensitive resin layer tends to be insufficient.

The content of (C) is preferably 15 to 60% by mass, more preferably 20 to 50% by mass, based on the total amount of (A), (B) and (C). If the content of (C) is less than 15% by mass, the crosslinkability tends to decrease and the photosensitivity tends to be insufficient. On the other hand, when it exceeds 60% by mass, the adhesiveness of the film surface of the photosensitive resin layer tends to increase.

The photosensitive resin composition of the present invention may be configured as a dry film resist (DFR) in which a support (carrier film) and a photosensitive resin layer are laminated. A photosensitive resin layer is a layer containing a photosensitive resin composition. Also, the DFR may have a structure in which a support, a photosensitive resin layer and a cover film are laminated.

The support is preferably a transparent film that transmits actinic rays. The thinner the thickness, the less light is refracted, and the thicker the thickness, the better the coating stability. Such films include films of polyethylene terephthalate, polycarbonate, and the like.

As the cover film, it is sufficient that the uncured or cured photosensitive resin layer can be peeled off, and a resin with high releasability is used. Examples thereof include polyethylene film, polypropylene film, and polyethylene film coated with a release agent such as silicon.

The thickness of the photosensitive resin layer is preferably 4-50 μm, more preferably 10-25 μm. If the photosensitive resin layer is too thick, problems such as a decrease in resolution and an increase in cost tend to occur. Conversely, if it is too thin, the adhesiveness and acid resistance tend to decrease.

Next, the plating method of the present invention will be described in detail. The plating method of the present invention can be applied to plating processes such as copper plating and nickel plating. Specifically, it is preferably used for applications such as the additive method for forming metal circuits, the semi-additive method, and the additive method for producing high-definition metal masks. In this method, a metal pattern is formed by plating the exposed base material other than the part. For example, when producing a printed wiring board, first, a substrate in which a thin metal layer is provided on an insulating substrate is prepared as a base material. Next, a resist pattern is formed on the portion where the circuit pattern is not formed. Electroplating is then performed to form a plated metal layer on the surface of the exposed thin metal layer. Subsequently, the resist pattern is removed by a resist stripping process. The circuit pattern is then formed by (flash) etching away the thin metal layer.

Examples of base materials include copper, copper-based alloys (titanium-copper alloys, copper-nickel alloys, etc.), nickel, chromium, iron, tungsten, iron-based alloys such as stainless steel and 42 alloy, and metal base materials such as aluminum and amorphous alloys. can be used. Copper-clad laminates, (non-)electrolytically plated substrates, flexible copper-clad laminates, flexible stainless steel plates, laminates, and the like, which are used in the manufacture of printed wiring boards, etc., can also be used.

A photo method is used to form a resist pattern on a substrate. In the photo method, first, a coating liquid containing a photosensitive resin composition is applied to a substrate and dried to form a photosensitive resin layer containing the photosensitive resin composition. A DFR may be prepared by forming a photosensitive resin layer on a carrier film in advance, and the photosensitive resin layer may be transferred to the substrate. Next, pattern exposure is performed to cure the exposed portion. Next, development is performed to remove the unexposed portion of the photosensitive resin layer, which is an unnecessary portion of the resist pattern, to form a resist pattern including the cured photosensitive resin layer.

As a developer used for development, for example, an aqueous solution of an inorganic basic compound can be used. Examples of inorganic basic compounds include carbonates and hydroxides of lithium, sodium, potassium and the like, and 0.1 to 3% by mass aqueous sodium carbonate solution can be preferably used. A small amount of a surfactant, an antifoaming agent, a solvent, or the like can be appropriately mixed in the developer. As the development processing method, there are a dip method, a battle method, a spray method, a brushing method, a scraping method, and the like, and the spray method is most suitable for removal speed. The treatment temperature is preferably 15-35° C., and the spray pressure is preferably 0.02-0.3 MPa.

In the present invention, the resist pattern after development may be baked. By the baking treatment, the effect of improving the adhesion between the photosensitive resin layer and the substrate, the effect of improving the plating resistance, and the like can be obtained. The baking temperature is preferably 80° C. or higher, and the baking time is preferably 5 minutes or longer. If the base material is copper or the like and is a material that is easily discolored by oxidation or the like, baking treatment is performed at about 80°C. If the base material is stainless steel or the like and is a material that is difficult to oxidize, the temperature of the baking treatment may be 100° C. or higher, and the baking treatment may be performed for a long time of 30 minutes or longer. Moreover, for the purpose of preventing deformation of the photosensitive resin layer due to heat, an actinic ray irradiation treatment such as ultraviolet rays may be performed before the baking treatment.

In the resist stripping process, an alkaline aqueous solution is usefully used as a resist stripping liquid. Examples of the basic compound used in the resist stripping solution include inorganic basic compounds such as alkali metal silicates, alkali metal hydroxides, alkali metal phosphates, alkali metal carbonates, ammonium phosphates, and ammonium carbonates. Compounds: organic basic compounds such as ethanolamine, ethylenediamine, propanediamine, triethylenetetramine, morpholine, and tetramethylammonium hydroxide. In the resist stripping process, it is necessary to adjust the concentration, temperature, spray pressure, ultrasonic wave conditions, etc. of the resist stripping solution in order to control the solubility in the cured photosensitive resin layer. The higher the temperature of the resist stripping solution, the faster the rate at which the cured photosensitive resin layer dissolves, so a temperature of 40° C. or higher is preferable. The concentration of the basic compound in the resist stripping solution is preferably a concentration suitable for solubility, and when the basic compound is sodium hydroxide, it is preferably 1 to 4% by mass. As a device, a dip processing device, an ultrasonic device, a shower spray device, or the like can be used.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

(Examples 1 to 7, Comparative Examples 1 to 12)
Each component shown in Table 1 was mixed to obtain a coating liquid of a photosensitive resin composition. In addition, the unit in the compounding quantity of each component in Table 1 is a mass part. The resulting coating solution is applied onto a polyethylene terephthalate (PET) film (trade name: R310, 16 μm thick, manufactured by Mitsubishi Chemical Corporation, support) using an applicator, dried at 80° C. for 8 minutes, By removing the solvent component, a DFR was obtained in which a photosensitive resin layer (dry film thickness: 15 μm) containing the photosensitive resin compositions of Examples 1 to 7 and Comparative Examples 1 to 12 was provided on one side of the PET film.

In Table 1, each component is as follows.

(A) Alkali-soluble resin (A-1) Copolymer resin obtained by copolymerizing styrene/methyl methacrylate/n-butyl acrylate/methacrylic acid at a mass ratio of 20/40/15/25 (mass average molecular weight 30,000)

(B) Photoinitiator (B-1) 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer (B-2) 4,4′-bis(diethylamino)benzophenone

(C) methacrylate monomer (C1)
(C-1) Ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l≈23)

(C2)
(C-2) Ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n≈10)

(C3)
(C-3) Ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n≈4)

Methacrylate monomers other than (C1) to (C3) (C-4) ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l≈14)
(C-5) Ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l≈44)
(C-6) Ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n≈2.6)
(C-7) Ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) where m+n≈17)

A stainless steel plate having a surface roughness Ra of 0.01 μm to 1 μm was subjected to surface treatment such as alkali degreasing and acid treatment, and the photosensitive resin layers of Examples 1 to 7 and Comparative Examples 1 to 12 were attached. Next, pattern exposure is performed through a photomask having a line and space (L/S) line pattern with a width of 7 μm and 6 μm, then the PET film is peeled off, and development is performed with a 1.0% by mass sodium carbonate aqueous solution. Then, the photosensitive resin layer in the non-exposed portions was removed to form a resist pattern including the cured photosensitive resin layer.

At this time, in Comparative Example 1 in which the content of (C-1) is higher than 20% by mass, the line pattern of lines and spaces with widths of 7 μm and 6 μm meanders due to swelling due to the development process, and part of the space An unexposed portion of the photosensitive resin layer remained.

In Comparative Example 2 in which the content of (C-2) is higher than 70% by mass, part of the line and space line patterns with widths of 7 μm and 6 μm are lifted from the substrate surface after the resist pattern is formed by development. seen.

In Comparative Example 3, in which the content of (C-3) is higher than 35% by mass, the line pattern of lines and spaces with widths of 7 μm and 6 μm remained on the substrate without deformation due to the development process, but the photosensitive resin A part of the non-exposed portion of the photosensitive resin layer remained in the form of a thin film on the surface of the base material where the layer was laminated.

In Comparative Example 4, in which the content of (C-1) was less than 10% by mass, more than half of the line and space line patterns with widths of 7 μm and 6 μm were lost due to the development process.

In Comparative Example 5, in which the content of (C-2) is less than 50% by mass, after pattern formation by development, a part of the unexposed portion of the photosensitive resin layer is added to the surface of the base material where the photosensitive resin layer is laminated. part remained in the form of a thin film. In addition, in the lines and spaces with widths of 7 μm and 6 μm, the unexposed portion of the photosensitive resin layer remained in part of the space.

In Comparative Example 6, in which the content of (C-3) is less than 15% by mass, a line pattern of lines and spaces with a width of 7 μm could be formed by the development process, but a line pattern of lines and spaces with a width of 6 μm was formed. It meandered due to swelling.

In Comparative Example 7 containing (C-4), half or more of the line pattern of lines and spaces with widths of 7 μm and 6 μm was lost due to the development process.

In Comparative Example 8 containing (C-5), the line pattern of lines and spaces with widths of 7 μm and 6 μm meandered due to swelling, and unexposed portions of the photosensitive resin layer remained in part of the spaces.

In Comparative Examples 9 and 10 including (C-6), after pattern formation by development, line patterns of lines and spaces with widths of 7 μm and 6 μm remained on the substrate without deformation, but the photosensitive resin layer was laminated. A part of the non-exposed part of the photosensitive resin layer remained in the form of a thin film on the surface of the base material.

In Comparative Examples 11 and 12 containing (C-7), the line pattern of lines and spaces with widths of 7 μm and 6 μm meandered due to swelling.

On the other hand, in Examples 1 to 7, even after development, line patterns of 7 μm wide and 6 μm wide lines and spaces remained on the substrate without deformation, and in the spaces, there was no residue from the non-exposed portions of the photosensitive resin layer. was not seen.

Next, observation with a microscope was performed, and Examples 1 to 7 and Comparative Examples 3, 6, 9 and 10 showed that there were line patterns in which line deformation due to swelling of the developer and line disappearance due to the development process did not occur. 10, by electrolytic plating using a nickel sulfamate (Ni) bath, a plating film was grown on the portion not covered by the resist pattern on the stainless steel plate to form a Ni metal layer with a thickness of 7 μm. formed.

At this time, in Comparative Examples 3, 9 and 10, the Ni metal layer did not grow because the thin film of the unexposed portion of the photosensitive resin layer was present on the substrate after development.

In Comparative Example 6, although a Ni metal layer having a good shape was formed in the space portion of the formed line and space with a width of 7 μm, the Ni metal layer was formed in the space portion of the line and space with a width of 6 μm that was meandering due to swelling. A shape defect was observed in the metal layer.

On the other hand, on the substrates of Examples 1 to 7, Ni metal layers with good shapes were formed.

Next, the resist pattern was removed by immersion in a 3% by mass aqueous sodium hydroxide solution (liquid temperature: 50°C). The resist patterns formed from the photosensitive resin compositions of Examples 1 to 7 and Comparative Examples 3, 6, 9 and 10 could be peeled off satisfactorily.

As described above, in Examples 1 to 7, good Ni plating was achieved.

INDUSTRIAL APPLICABILITY The present invention can be widely used as a photosensitive resin composition. It can also be used as a plating method for plating in the manufacture of printed wiring boards, lead frames, metal masks, shadow masks, semiconductor packages, electrode members, electromagnetic wave shields, and the like.

Claims (2)

(A) an alkali-soluble resin, (B) a photopolymerization initiator and (C) a methacrylate monomer,
(C) As methacrylate monomers, (C1) ethylene oxide-modified dimethacrylate (compound represented by general formula (i) where l = 16 to 30), (C2) ethylene oxide-modified bisphenol A-type dimethacrylate (general formula ( ii) and m+n=5 to 16) and (C3) ethylene oxide-modified bisphenol A-type dimethacrylate (compound represented by general formula (ii) and m+n=3 to 4),
(C) The content of (C1) ethylene oxide-modified dimethacrylate (a compound represented by the general formula (i) where l = 16 to 30) is 10 to 20 mass% with respect to the total amount of methacrylate monomer, C2) The content of ethylene oxide-modified bisphenol A type dimethacrylate (compound represented by general formula (ii) where m+n = 5 to 16) is 50 to 70% by mass, and (C3) ethylene oxide-modified bisphenol A type A photosensitive resin composition containing 15 to 35% by mass of a dimethacrylate (a compound represented by the general formula (ii) where m+n=3 to 4).

The step of forming a photosensitive resin layer containing the photosensitive resin composition according to claim 1 on a substrate, the step of performing pattern exposure to cure the exposed portion, and performing development to unexpose the photosensitive resin layer. A plating method, comprising the steps of: removing a portion to form a resist pattern including a cured photosensitive resin layer; and plating the exposed substrate by removing the unexposed portion of the photosensitive resin layer.