JP2016102828A - Photosensitive resin composition for plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition for plating, which allows easy stripping of a resist pattern and hardly leaves a residual portion after stripping, even in a metal pattern having a narrow pitch, and which has high acid resistance.SOLUTION: The photosensitive resin composition for plating comprises at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a polyfunctional acrylate monomer, and (D) a urethane compound having a terminal acrylate group obtained from a polyhydric alcohol, a diisocyanate compound, a lactone compound, and an acrylate compound having a hydroxyl group. A photocured portion of the photosensitive resin composition is dissolved in a resist stripping solution or dispersed as fine particles in the resist stripping solution.SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive resin composition for plating.

  In recent years, with respect to printed wiring boards, metal masks, and the like, pattern miniaturization has been promoted as electronic devices become smaller and lighter. Therefore, in the production of a conductor circuit of a printed wiring board or a metal mask, a metal pattern is produced by a (semi) additive method using a photosensitive resin composition and electrolytic plating.

  For example, the (semi) additive method in the production of a printed circuit board conductor circuit first forms a thin copper layer by electroless plating on the surface of an insulating resin such as glass epoxy resin, and then forms a photosensitive resin layer on the surface of the copper layer. Then, exposure and development are performed to form a resist pattern. Further, a copper layer by electrolytic plating is laminated on the copper layer by electroless plating, and the entire copper layer is thickened. In this method, a resist pattern is peeled off, and a copper layer formed by electroless plating that appears after peeling is etched to produce a metal pattern (for example, Patent Document 1).

  In addition, for example, an additive method for producing a metal mask includes a first step of forming a photosensitive resin layer having a predetermined thickness on a substrate, and pattern exposure on the photosensitive resin layer in accordance with the opening of the metal mask. A second step of developing, a third step of developing only a non-exposed portion of the photosensitive resin layer to form a resist pattern and exposing the base material, and a metal mask material by electrolytic plating on the exposed portion of the base material After performing the 4th process of forming a layer, the 5th process of removing a resist pattern by removing the remaining photosensitive resin layer with a resist stripping solution, and the 6th process of separating a metal mask material layer from a substrate This is a method for producing a metal pattern (for example, Patent Document 2).

  When a narrow pitch metal pattern is formed by electrolytic plating, a thick metal layer is formed in a narrow space between resist patterns. However, in the subsequent process of peeling the resist pattern, there is a problem of residual peeling that the resist pattern is not normally peeled off and the resist remains.

  Moreover, copper plating, nickel plating, etc. are used as electrolytic plating. However, there is a problem that the plating bath is strongly acidic and the fine resist pattern is peeled off.

JP 2004-101617 A JP-A-4-166844

  An object of the present invention is to provide a photosensitive resin composition for plating that can easily peel off a resist pattern even in a narrow-pitch metal pattern, hardly causes a peeling residue, and has high acid resistance. is there.

  As a result of intensive studies to solve the above problems, at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a polyfunctional acrylate monomer, (D) a polyhydric alcohol, a diisocyanate compound, and a lactone A urethane compound having an acrylate group at the terminal obtained from the compound and an acrylate compound having a hydroxyl group, and the photocured portion of the photosensitive resin composition is dissolved or dispersed as fine particles in the resist stripping solution. The above-described problems have been solved by the characteristic photosensitive resin composition for plating.

  According to the photosensitive resin composition for plating of the present invention, a resist pattern can be easily peeled even in a narrow-pitch metal pattern, a peeling residue hardly occurs, and it has acid resistance. Resist peeling in the resist pattern hardly occurs and a fine metal pattern can be formed.

  Hereinafter, the photosensitive resin composition for plating of the present invention (hereinafter sometimes abbreviated as “photosensitive resin composition”) will be described in detail.

  (A) Examples of the alkali-soluble resin include a carboxyl group-containing acrylic resin. Examples of the carboxyl group-containing acrylic resin include an acrylic polymer having (meth) acrylate as a main component and copolymerized with an ethylenically unsaturated carboxylic acid. Further, other monomers having a copolymerizable ethylenically unsaturated group may be copolymerized.

  Examples of the (meth) acrylate 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, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2- (dimethylamino) ethyl (meth) acrylate, 2- (diethylamino) ethyl (meth) acrylate, 2, , 2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate.

  Monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid are preferably used as the ethylenically unsaturated carboxylic acid, and dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and anhydrides and half esters thereof. It can also be used. Among these, acrylic acid and methacrylic acid are particularly preferable.

  Examples of the other monomer having a copolymerizable ethylenically unsaturated group include styrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, p-ethoxystyrene, p. -Chlorostyrene, p-bromostyrene, (meth) acrylonitrile, (meth) acrylamide, diacetone acrylamide, vinyl toluene, vinyl acetate, vinyl-n-butyl ether and the like.

  (A) It is preferable that the acid value of alkali-soluble resin is 30-500 mgKOH / g, and it is more preferable that it is 100-300 mgKOH / g. When the acid value is less than 30 mgKOH / g, the alkali development time tends to be long. On the other hand, when it exceeds 500 mgKOH / g, it may become hard and adhesiveness may fall.

  The mass average molecular weight of the (A) alkali-soluble resin is preferably 10,000 to 200,000, and more preferably 10,000 to 150,000. When the mass average molecular weight is less than 10,000, it may be difficult to form the photosensitive resin composition for plating of the present invention in a film state. On the other hand, if it exceeds 200,000, the solubility in an alkali developer tends to deteriorate.

  (B) As the photopolymerization initiator, benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy- 4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone- Aromatic ketones such as 1; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenyl Anthraquinone, 1-chloroanthraquinone, -Quinones such as methyl anthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethylanthraquinone; benzoin methyl ether, benzoin ethyl ether, benzoin phenyl Benzoin ether compounds such as ether; benzoin compounds such as benzoin, methylbenzoin, and ethylbenzoin; benzyl derivatives such as benzyldimethyl ketal; 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o- Chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenyl Imidazole dimer, 2- (p- 2,4,5-triarylimidazole dimers such as toxiphenyl) -4,5-diphenylimidazole dimer; acridines such as 9-phenylacridine, 1,7-bis (9,9'-acridinyl) heptane Derivatives: N-phenylglycine, N-phenylglycine derivatives, coumarin compounds and the like. The substituents of the aryl groups of two 2,4,5-triarylimidazoles in the 2,4,5-triarylimidazole dimer may give the same and symmetrical compounds, but differently Asymmetric compounds may be provided. Moreover, you may combine a thioxanthone type compound and a tertiary amine compound like the combination of diethyl thioxanthone and dimethylaminobenzoic acid. These are used alone or in combination of two or more.

  (C) As a polyfunctional acrylate monomer, the compound which has two or more acryloyl groups is mentioned. For example, the compound obtained by making two acrylic acids react with polyhydric alcohol is mentioned. Ethylene glycol diacrylate, polyethylene glycol diacrylate (having 2 to 30 ethoxy groups), propylene glycol diacrylate, polypropylene glycol diacrylate (having 2 to 30 propoxy groups), polytetramethylene glycol diacrylate, neopentyl glycol Diacrylate, 3-methyl-1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, 1,10-decanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol tricyclodecane diacrylate , Diacrylate of bisphenol A ethylene oxide adduct (having 2 to 30 ethoxy groups), Diacrylate of bisphenol A propylene oxide adduct Having 2 to 40 poxy groups), diacrylate of ethylene oxide and propylene oxide adducts of bisphenol A (the sum of ethoxy groups and propoxy groups being 2 to 40), neopentyl glycol diacrylate hydroxypivalate, Examples include 9-bis [4- (2-acryloyloxyester) phenyl] fluorin, tricyclodecane dimethanol diacrylate, and the like. Among these, polyethylene glycol diacrylate can be usefully used for the flexibility of the photosensitive resin layer and the adhesion to the substrate. Examples of the compound having three or more acryloyl groups include a compound obtained by reacting polyhydric alcohol with acrylic acid. Also, for example, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated pentaerythritol triacrylate, trimethylolpropane triglycidyl Examples include ether triacrylate, ethoxylated isocyanuric acid triacrylate, ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate, glycerin triacrylate, and ethoxylated glycerin triacrylate. Especially, pentaerythritol triacrylate can be usefully used from the point of the solubility of the resist peeling in the photocuring part of the photosensitive resin layer.

  The polyhydric alcohol related to the component (D) can be used without particular limitation as long as it has two or more hydroxyl groups. Specifically, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polypentamethylene glycol, bisphenol A, hydroquinone, dihydroxycyclohexanone, trimethylolpropane, tetra Examples include methylolpropane, pentaerythritol, dipentaerythritol and the like.

  As the diisocyanate compound related to the component (D), dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, 2,2-dimethylpentane-1,5-diisocyanate, octane Methylene diisocyanate, 2,5-dimethylhexane-1,6-diisocyanate, 2,2,4-trimethylpentane-1,5-diisocyanate, nonamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, decamethylene diisocyanate, isophorone Aliphatic or alicyclic diisocyanate compounds such as diisocyanate can be used.

  As the lactone compound related to the component (D), δ-valerolactan, ε-caprolactone, β-propiolactone, α-methyl-β-propiolactone, β-methyl-β-propiolactone, α, α- Examples thereof include dimethyl-β-propiolactone and β, β-dimethyl-β-propiolactone.

  Specific examples of the acrylate compound having a hydroxyl group related to the component (D) include hydroxymethyl acrylate, 2-hydroxyethyl acrylate, and 3-hydroxypropyl acrylate.

  As the resist stripping solution according to the present invention, an alkaline aqueous solution is usefully used. For example, an aqueous solution of an inorganic basic compound such as alkali metal silicate, alkali metal hydroxide, phosphoric acid or alkali metal carbonate, phosphoric acid or ammonium carbonate; ethanolamine, ethylenediamine, propanediamine, triethylenetetramine, morpholine An aqueous solution of an organic basic compound such as tetramethylammonium hydroxide can be used. In order to control the solubility of the photocured portion of the photosensitive resin layer in these resist stripping solutions, it is necessary to adjust the concentration and temperature of the resist stripping solution, the spray pressure when supplying the resist stripping solution, and the like. The higher the temperature of the resist stripping solution, the faster the dissolution rate, and a temperature of 40 ° C. or higher is preferable. The concentration of the resist stripping solution is preferably a concentration suitable for solubility, and is preferably 1 to 4% by mass for sodium hydroxide. As the apparatus, a dip processing apparatus, an ultrasonic apparatus, a shower spray apparatus, or the like can be used.

  The photosensitive resin composition for plating according to the present invention is photocured by exposure, and in some cases, the baked photosensitive resin layer is removed by a resist stripping solution and dissolved or the strips become very fine and become fine particles. scatter. In the present invention, “the photocured part is dissolved in the resist stripping solution or dispersed as fine particles” means that it is dispersed at the molecular level or in the state of fine particles of 500 μm or less. Generally, the photosensitive resin composition contains an acrylate group-containing crosslinking agent and a methacrylate group-containing crosslinking agent as reactive components. In the photosensitive resin composition for plating of the present invention, in order for the photocured part to be dissolved or dispersed in the resist stripping solution, the reactive component does not include a commonly used methacrylate group-containing crosslinking agent, and acrylate. It contains a group-containing crosslinking agent as a main component. That is, (C) the polyfunctional acrylate monomer must not be a polyfunctional methacrylate monomer, and the acrylate compound having a hydroxyl group related to the component (D) must not be a methacrylate compound having a hydroxyl group. If the release piece of the photocured part is large, there is a problem of reattaching to the fine part of the metal pattern, but as in the present invention, there is a problem that the release piece reattaches to the metal pattern by being dissolved or dispersed as fine particles. Reduce.

  You may make the photosensitive resin composition of this invention contain components other than the said component (A)-(D) as needed. Such components include photopolymerizable monomers, solvents, thermal polymerization inhibitors, plasticizers, colorants (dyes, pigments), photochromic agents, photochromic agents, thermochromic inhibitors, fillers, antifoaming Agents, flame retardants, adhesion-imparting agents, leveling agents, peeling accelerators, antioxidants, fragrances, thermosetting agents, water and oil repellents, and the like, each containing about 0.01 to 20% by mass. Can do. 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 amount of the component (A) is preferably 30 to 70% by mass with respect to the total amount of the components (A), (B), (C), and (D). 40 to 60% by mass is more preferable. When the blending amount of the component (A) is less than 30% by mass, the film property may be deteriorated or the alkali developability may be deteriorated. When the compounding amount of the component (A) exceeds 70% by mass, the resolution of the resist pattern with the substrate may be lowered.

  The blending amount of the component (B) is preferably 0.1 to 10% by mass, and 0.2 to 5% by mass with respect to the total amount of the components (A), (B), (C) and (D). It is more preferable that When the blending amount of the component (B) is less than 0.1% by mass, the photopolymerizability tends to be insufficient. On the other hand, if it exceeds 10% by mass, absorption increases on the surface of the photosensitive resin layer during exposure, and photocuring inside the photosensitive resin layer tends to be insufficient.

  The compounding amount of the component (C) is preferably 5 to 40% by mass and preferably 10 to 30% by mass with respect to the total amount of the components (A), (B), (C) and (D). More preferred. When the blending amount of the component (C) is less than 5% by mass, there is a tendency that the crosslinkability is lowered and the photosensitivity is insufficient. On the other hand, when it exceeds 40 mass%, the adhesiveness of the film surface tends to increase.

  The blending amount of component (D) is preferably 5 to 55% by mass, and preferably 10 to 50% by mass, based on the total amount of components (A), (B), (C) and (D). More preferred. When the blending amount of the component (D) is less than 5% by mass, the acid resistance tends to decrease and the tackiness increases before photocuring. On the other hand, if it exceeds 55% by mass, the generation of edge fusion, resolution and photosensitivity tend to be insufficient.

  The photosensitive resin composition of the present invention can be used as a liquid photosensitive composition in which each component is dissolved in a solvent, applied to a target substrate, and the solvent is dried. Examples of the coating method include roll coating, curtain coating, dip coating, and spin coating. The coating film thickness is preferably 5 to 50 μm. Moreover, it is good also as a structure of the dry film which laminated | stacked the support body, the photosensitive resin layer, and the cover film. The support is preferably a transparent film that transmits actinic rays. A thinner thickness is preferable because light refraction is less, and a thicker thickness is preferable because of excellent coating stability, but a thickness of 5 to 50 μm is preferable. Examples of such a film include films of polyethylene terephthalate and polycarbonate. The cover film only needs to be able to peel off the uncured or cured photosensitive resin layer, and a resin having a high releasability is used. For example, a polyethylene film, a polypropylene film, etc. are mentioned. It may be a film coated with a release agent such as silicon. The photosensitive resin layer is a layer made of a photosensitive resin composition.

  The thickness of the photosensitive resin layer is preferably 10 to 150 μm, and more preferably 30 to 120 μm. If the thickness of the photosensitive resin layer is too large, problems such as a decrease in resolution and high costs are likely to occur. On the other hand, if it is too thin, adhesion and acid resistance tend to decrease.

  The plating according to the present invention is electrolytic plating, and includes plating using an acidic bath such as copper plating, nickel plating, and zinc plating. For example, a method for producing a metal pattern by nickel plating includes a (semi) additive method and a method for producing a metal mask by an additive method in producing a conductor circuit of a printed wiring board. In the (semi) additive method for the production of printed circuit board conductor circuits, a photosensitive resin layer is first formed on the surface of a copper layer of a base material that is formed by electroless plating on the surface of an insulating resin such as glass epoxy resin. Next, exposure and development are performed to form a resist pattern. Further, a copper layer by electroplating is laminated on the copper layer by electroless plating, and the entire copper layer is thickened. The copper layer by electroless plating that appears after peeling is etched to produce a metal pattern. In the metal mask manufacturing method, for example, a photosensitive resin layer is formed on a base material that is a base, and then a resist pattern is formed by performing exposure and development, on a base material that is not covered with the photosensitive resin layer. Then, the resist pattern and the base material are removed to obtain a metal mask which is a screen printing mask. Although the (semi) additive method takes time, the productivity is low and the cost is high, but a fine opening pattern can be formed. Therefore, it is used in the field where a narrow pitch metal pattern is required, and is used for manufacturing a printed wiring board having a high wiring density or a bump mask or the like that requires higher-definition printing. In the present invention, the narrow pitch metal pattern is a metal pattern such as lines & spaces, dots, openings, etc. of 70 μm or less.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example.

(Reference Example 1)
Plaxel (registered trademark) 220 [polycaprolactone polyol manufactured by Daicel Corporation, number average molecular weight 2000] is reacted with 100 parts by mass of 17 parts by mass of hexamethylene diisocyanate, and further with 12 parts by mass of 2-hydroxyethyl acrylate. Thus, urethane acrylate (UA-1) having a number average molecular weight of 2500 was obtained.

(Reference Example 2)
Plaxel (registered trademark) 320 [polycaprolactone polyol manufactured by Daicel Corporation, number average molecular weight 2000] is reacted with 100 parts by mass of 17 parts by mass of hexamethylene diisocyanate, and further with 12 parts by mass of 2-hydroxyethyl acrylate. Thus, urethane acrylate (UA-2) having a number average molecular weight of 2500 was obtained.

(Reference Example 3)
50 parts by mass of polypropylene glycol [number average molecular weight 1000] is reacted with 17 parts by mass of hexamethylene diisocyanate, and further reacted with 12 parts by mass of 2-hydroxyethyl acrylate to give urethane acrylate having a number average molecular weight of 1500 (UA-3). Got.

(Reference Example 4)
Plaxel (registered trademark) 320 [polycaprolactone polyol manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 2000] is reacted with 17 parts by mass of hexamethylene diisocyanate, and 13 parts by mass of 2-hydroxyethyl methacrylate is further reacted. By reacting, urethane acrylate (UA-4) having a number average molecular weight of 2500 was obtained.

(Examples 1-4, Comparative Examples 1-3)
Each component shown in Table 1 was mixed to obtain a photosensitive resin composition. In addition, the unit of each component compounding amount in Table 1 represents a mass part. The obtained coating solution was coated on a polyethylene terephthalate (PET) film (trade name: R310, 25 μm thickness, manufactured by Mitsubishi Plastics) using a wire bar, and dried at 80 ° C. for 8 minutes. The solvent component was skipped and the photosensitive film which provided the photosensitive resin layer (dry film thickness: 30 micrometers) which consists of the photosensitive resin composition of Examples 1-4 and Comparative Examples 1-3 on the single side | surface of PET film was obtained. .

In Table 1, each component is as follows.
(A-1) Copolymerized resin (mass average molecular weight 70000) obtained by copolymerizing methyl methacrylate / n-butyl acrylate / methacrylic acid at a mass ratio of 60/15/25
(B-1) 2- (2'-chlorophenyl) -4,5-diphenylimidazole dimer (B-2) 4,4'-bis (diethylamino) benzophenone (C-1) polyethylene glycol diacrylate (ethoxy group number) 4)
(C-2) Polyethylene glycol diacrylate (the number of ethoxy groups is 9)
(C-3) Pentaerythritol triacrylate

  Surface treatments such as alkali degreasing and acid treatment were carried out on stainless steel plates having a surface roughness Ra of 0.01 μm to 1 μm, and the photosensitive films obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were attached. . Next, the photosensitive resin layer is exposed through a photomask having a 50 μm line & space pattern, then the PET film is peeled off, and alkali development is performed with a 1% by mass aqueous sodium carbonate solution. The photosensitive resin layer was removed and a resist pattern was formed.

  Next, an Ni plating film was grown on an uncoated portion of the resist pattern on the stainless steel plate by electrolytic plating using a nickel sulfamate (Ni) bath to form a Ni layer (25 μm thick).

  At this time, when the photosensitive resin compositions of Comparative Examples 1 and 3 were used, it was found that the plating solution soaked into the bottom of the line and the acid resistance of the resist pattern was low. Therefore, the Ni layer entered under the resist pattern, and a good Ni pattern could not be produced.

  Next, the resist pattern was stripped by dipping in a 3% by mass aqueous sodium hydroxide solution (resist stripper). When the photosensitive resin compositions of Examples 1 to 4 were used, peeling could be performed satisfactorily. When the photosensitive resin composition of Comparative Example 2 was used, the peeled piece was not dissolved, and a resist pattern peeled residue remained in a 50 μm space, causing a problem.

  Moreover, as a result of immersing the peeling piece of the photocured part of the photosensitive resin composition of Examples 1 to 4 in a 3% by mass sodium hydroxide aqueous solution (resist peeling liquid) for 1 hour, the peeling piece cannot be visually confirmed. It was confirmed that the photocured part was dissolved or dispersed as fine particles in the resist stripping solution. As a result, when the resist pattern is continuously peeled, there is no concern that the resist pattern peeling pieces between the Ni patterns may be entangled when the next workpiece is processed.

  The present invention can be used as a photosensitive resin composition for plating.

Claims (1)

  It is obtained from at least (A) an alkali-soluble resin, (B) a photopolymerization initiator, (C) a polyfunctional acrylate monomer, (D) a polyhydric alcohol, a diisocyanate compound, a lactone compound, and an acrylate compound having a hydroxyl group. A photosensitive resin composition for plating, comprising a urethane compound having an acrylate group at a terminal, wherein a photocured portion of the photosensitive resin composition is dissolved or dispersed as fine particles in a resist stripping solution.