JP7216506B2 - Photosensitive resin composition for plating resist, method for producing dry film and printed wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive resin composition for plating resist, a dry film, and a method for producing a printed wiring board.

2. Description of the Related Art In recent years, portable information communication terminals typified by mobile devices and the like are favored as lightweight and compact products because of their intended use. As a result, the printed wiring board used inside such portable information communication terminals has seen an increase in the number of parts mounted and a wide variety of products, and it has become possible to connect various parts on a single printed wiring board. It has been demanded.

Conventionally, there has been proposed a method of partially applying surface treatment such as solder plating or nickel/gold plating to a conductor pad to which a component is connected (see Patent Document 1). According to this patent document, by partially forming a plating resist, it is possible to arbitrarily select a portion to be nickel/gold-plated and a portion not to be plated, and various parts can be connected.

On the other hand, in the technique of partially nickel/gold plating treatment, exposure/development type plating resist is mainly used. Patent Document 1 describes that there is a problem of elution of
On the other hand, this patent document proposes a method of using a thermosetting or ultraviolet curing plating resist and performing processing in a short number of steps and in a short manufacturing time, thereby solving this problem.

JP 2007-12735 A

Therefore, the present invention provides an exposure/development type plating resist that has a sufficient inhibitory effect on elution into the nickel plating solution and a decrease in the plating deposition rate, and has sufficient peelability after plating, so that it can be produced. A main object of the present invention is to provide a photosensitive resin composition for a plating resist with high resistance.
Another object of the present invention is to provide a method for producing a dry film and a printed wiring board using the above photosensitive resin composition for plating resist.

The inventors have found that the component eluted into the nickel plating solution is the photopolymerization initiator in the plating resist, and have made earnest studies to achieve the above object. As a result, by using a titanocene-based photopolymerization initiator as a photopolymerization initiator, it is possible to sufficiently suppress the elution of the plating resist component into the nickel plating solution and the decrease in the plating deposition rate, as well as the sufficient peelability after the plating treatment. The present inventors have found that both of the above can be achieved, and have completed the present invention.

That is, the photosensitive resin composition for a plating resist of the present invention is characterized by comprising (A) an alkali-soluble resin, (B) a photopolymerizable monomer, and (C) a titanocene-based photopolymerization initiator. It is.

The photosensitive resin composition for a plating resist of the present invention preferably further contains (D) a photopolymerization initiator other than the titanocene-based photopolymerization initiator (C), and the amount thereof is It is preferably 2% by mass or less with respect to the photopolymerizable monomer, and the photopolymerization initiator excluding (D) the titanocene photopolymerization initiator (C) is an oxime ester photopolymerization initiator. is desirable.

The dry film of the present invention is obtained by forming a resin layer comprising the photosensitive resin composition for plating resist on a film.

The method for producing a printed wiring board of the present invention forms a coating made of the photosensitive resin composition for plating resist or the resin layer of the dry film on a printed wiring board having a conductor circuit or a solder resist on the conductor circuit. a step of providing a light-irradiated portion and a light-unirradiated portion in the film; a step of removing the light-unirradiated portion of the film with a developer to expose a conductor circuit; and after plating the exposed conductor circuit. and a step of removing the light-irradiated portion of the coating with a stripping solution.

According to the present invention, even if it is an exposure/development type plating resist, it has a high inhibitory effect on the elution of the plating resist component into the nickel plating solution and the decrease in the plating deposition rate, and the peelability after the plating treatment is high. , a photosensitive resin composition for a plating resist with high productivity can be provided.

The photosensitive resin composition for plating resist of the present invention is most characterized in that a titanocene-based photopolymerization initiator is used as the photopolymerization initiator.
The inventors have identified that the causative component of plating bath contamination is the photopolymerization initiator, and have found that the molecular weight has an effect. Inferred that the elution into the plating solution is accelerated, the inventors have found that a titanocene-based photopolymerization initiator is used as the photopolymerization initiator. That is, by using a titanocene-based photopolymerization initiator, which has a relatively large molecular weight and is a non-self-cleavage (photobleaching) photopolymerization initiator, nickel plating can be achieved even with an exposure/development type plating resist. It is possible to achieve both an effect of suppressing elution into the liquid and a decrease in plating deposition rate, and sufficient peelability after plating.

In addition, in the present invention, by further combining a specific amount of an oxime ester photopolymerization initiator that can obtain photocurability even in a small amount, the titanocene photopolymerization initiator can be used from the viewpoint of the photocurability of the coating film surface. The function can be supplemented, and the effects described above can be further enhanced.

Next, each component of the photosensitive resin composition for plating resist of the present invention will be described.
In this specification, (meth)acrylate is a generic term for acrylate, methacrylate and mixtures thereof, and the same applies to other similar expressions.

[(A) alkali-soluble resin]
(A) As the alkali-soluble resin, conventionally known various carboxyl group-containing resins having a carboxyl group in the molecule can be used. When the photosensitive resin composition for plating resists contains (A) an alkali-soluble resin, the alkali releasability of the photosensitive resin composition for plating resists can be improved. Further, (A) the alkali-soluble resin may have an ethylenically unsaturated double bond in the molecule, and by having the ethylenically unsaturated double bond, the photocurable resin composition for the plating resist is It is possible to improve the durability and improve the plating resistance.
(A) Specific examples of the alkali-soluble resin include the following compounds (both oligomers and polymers).

(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid and an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, isobutylene, or the like.

(2) Diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates; Carboxyl group-containing urethane resins obtained by polyaddition reaction of diol compounds such as polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

(3) Diisocyanate and bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin ( A carboxyl group-containing photosensitive urethane resin produced by a polyaddition reaction of a meth)acrylate or its partial acid anhydride modified product, a carboxyl group-containing dialcohol compound and a diol compound.

(4) During the synthesis of the resin (2) or (3), a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule such as hydroxyalkyl (meth)acrylate is added, and the terminal ( Meta) acrylated carboxyl group-containing photosensitive urethane resin.

(5) During the synthesis of the resin of (2) or (3), one isocyanate group and one or more (meth)acryloyl groups are added in the molecule, such as an equimolar reaction product of isophorone diisocyanate and pentaerythritol triacrylate. A carboxyl group-containing photosensitive urethane resin that is terminally (meth)acrylated by adding a compound having

(6) A carboxyl group-containing photosensitive resin obtained by reacting (meth)acrylic acid with a polyfunctional (solid) epoxy resin having a functionality of 2 or more and adding a dibasic acid anhydride to the hydroxyl group present in the side chain.

(7) A carboxyl obtained by reacting (meth)acrylic acid with a polyfunctional epoxy resin obtained by further epoxidizing the hydroxyl group of a bifunctional (solid) epoxy resin with epichlorohydrin, and adding a dibasic acid anhydride to the resulting hydroxyl group. Group-containing photosensitive resin.

(8) A bifunctional oxetane resin is reacted with a dicarboxylic acid such as adipic acid, phthalic acid, and hexahydrophthalic acid, and the resulting primary hydroxyl group is treated with a dibasic such as phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride. Carboxyl group-containing polyester resin to which acid anhydride is added.

(9) an epoxy compound having a plurality of epoxy groups in one molecule, a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol; Maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, adipic acid to the alcoholic hydroxyl group of the reaction product obtained by reacting with a monocarboxylic acid containing an unsaturated group such as acrylic acid. A carboxyl group-containing photosensitive resin obtained by reacting a polybasic acid anhydride such as an acid.

(10) A reaction product obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide and reacting an unsaturated group-containing monocarboxylic acid to obtain a reaction product A carboxyl group-containing photosensitive resin obtained by reacting a polybasic acid anhydride with a substance.

(11) A reaction obtained by reacting a reaction product obtained by reacting a compound having a plurality of phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate with a monocarboxylic acid containing an unsaturated group. A carboxyl group-containing photosensitive resin obtained by reacting the product with a polybasic acid anhydride.

(12) A carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resins of (1) to (11).

(A) The acid value of the alkali-soluble resin is preferably 20 to 400 mgKOH/g. (A) By setting the acid value of the alkali-soluble resin to 20 mgKOH/g or more, alkali developability and peelability are improved. Further, by setting the acid value to 400 mgKOH/g or less, it is possible to suppress the penetration of the plating solution into the film. More preferably 80-300 mgKOH/g, still more preferably 100-250 mgKOH/g.

(A) The weight average molecular weight of the alkali-soluble resin varies depending on the resin skeleton, but is generally preferably from 5,000 to 150,000. By setting the weight average molecular weight to 5000 or more, the film strength can be improved. Further, by setting the weight average molecular weight to 150,000 or less, alkali developability and peelability can be improved. More preferably 10,000 to 120,000, still more preferably 20,000 to 100,000.

(A) The content of the alkali-soluble resin is preferably 10 to 90% by mass in terms of solid content in the photosensitive resin composition. By making it 10% by mass or more, coatability, film strength, alkali developability and releasability can be improved. Moreover, plating resistance improves by making it 90 mass % or less. More preferably 20 to 80% by mass, still more preferably 30 to 70% by mass.

These (A) alkali-soluble resins can be used without being limited to those listed above. One type may be used alone, or two or more types may be used in combination. It is preferable that the compound (1) is included from the viewpoint of the balance of adhesion and peelability after plating.

[(B) Photopolymerizable Monomer]
The photosensitive resin composition for plating resist of the present invention contains a photopolymerizable monomer. A photopolymerizable monomer is a compound having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include alkyl (meth)acrylates such as 2-ethylhexyl (meth)acrylate and cyclohexyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; Hydroxyalkyl (meth)acrylates such as acrylates; mono- or di(meth)acrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane , dipentaerythritol, polyhydric alcohols such as trishydroxyethyl isocyanurate, or polyhydric (meth)acrylates of ethylene oxide or propylene oxide adducts thereof; phenoxyethyl (meth)acrylate, polyethoxydi(meth)acrylate of bisphenol A, etc. (Meth)acrylates of ethylene oxide or propylene oxide adducts of phenols; (meth)acrylates of glycidyl ethers such as glycerol diglycidyl ether, trimethylolpropane triglycidyl ether and triglycidyl isocyanurate; and melamine (meth)acrylates is mentioned.

The photopolymerizable monomers are not limited to those listed above, and any known and commonly used monomers may be used. One type may be used alone, or two or more types may be used in combination, It preferably contains one or more of ethoxylated bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and polyethylene glycol di(meth)acrylate, more preferably all three. The inclusion of ethoxylated bisphenol A di(meth)acrylate and polyethylene glycol di(meth)acrylate improves adhesion and peelability in gold plating, and the inclusion of trimethylolpropane tri(meth)acrylate provides resistance to gold plating. improves.

The content of the photopolymerizable monomer is preferably 1 to 60 parts by mass with respect to 100 parts by mass of the alkali-soluble resin (A). When the blending amount is 1 part by mass or more, the photocurability is good, and pattern formation is facilitated in alkali development after irradiation with active energy rays. On the other hand, when the content is 60 parts by mass or less, halation is less likely to occur and good resolution can be obtained. More preferably, the ratio is 10 to 50 parts by mass.

で示されるビス（η５－シクロペンタジエニル）－ビス（２，６－ジフルオロ－３－（１Ｈ－ピロール－１－イル）フェニル）チタニウムが光硬化性、供給体制の面から好ましい。チタノセン系光重合開始剤は、前記列挙したものに限らず公知慣用のものをいずれも使用することができ、１種類を単独で使用してもよく、２種以上を組み合わせて使用してもよい。 [(C) Titanocene-based photopolymerization initiator]
The photosensitive resin composition for a plating resist of the present invention contains (C) a titanocene-based photopolymerization initiator. Titanocene-based photopolymerization initiators (C) include bis(cyclopentadienyl)-di-chloro-titanium, bis(cyclopentadienyl)-di-phenyl-titanium, bis(cyclopentadienyl)-bis( 2,3,4,5,6 pentafluorophenyl)titanium, bis(cyclopentadienyl)-bis(2,6difluorophenyl)titanium, bis(η5-cyclopentadienyl)-bis(2,6-difluoro -3-(1H-pyrrol-1-yl)phenyl)titanium and the like, among which the following formula ( 1 )

Bis(η5-cyclopentadienyl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium represented by is preferable in terms of photocurability and supply system. The titanocene-based photopolymerization initiator is not limited to those listed above, and any known and commonly used one can be used, and one type may be used alone, or two or more types may be used in combination. .

The blending amount of these titanocene-based photopolymerization initiators (C) is preferably 0.1 to 2.0 parts by mass per 100 parts by mass of the photopolymerizable monomer (B). When the blending amount is 0.1 part by mass or more, the photocurability is improved and the shape is good. On the other hand, when the content is 2.0 parts by mass or less, the balance between shape and releasability is good. More preferably, the ratio is 0.2 to 1.0 parts by mass.

[(D) Photopolymerization initiator other than titanocene-based photopolymerization initiator (C)]
The photosensitive resin composition for a plating resist of the present invention can use (C) a titanocene-based photopolymerization initiator together with (D) a photopolymerization initiator other than the titanocene-based photopolymerization initiator (C). (D) Photopolymerization initiators other than the titanocene-based photopolymerization initiator (C) can be any known and commonly used ones, and one type may be used alone, or two or more types may be used in combination. Although they may be used, oxime-based photopolymerization initiators are preferred because even a small amount can supplement the titanocene-based photopolymerization initiators from the viewpoint of photocuring of the coating film surface.

Specific examples of the oxime ester-based photopolymerization initiator (B) as the photopolymerization initiator include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide and bis-(2,6-dichlorobenzoyl )-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis -(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2, Bisacylphosphine oxides such as 5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichloro Benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2-methylbenzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid isopropyl ester, 2,4,6-trimethylbenzoyldiphenylphosphine monoacylphosphine oxides such as fin oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxy-cyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2 -hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane- Hydroxyacetophenones such as 1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzoin, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin n -benzoins such as butyl ether; benzoin alkyl ethers; benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone and other benzophenones; phenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio) Phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl) Acetophenones such as methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone and N,N-dimethylaminoacetophenone; thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone , 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone , 2-amyl anthraquinone, 2-aminoanthraquinone, and other anthraquinones; acetophenone dimethyl ketal, benzyl dimethyl ketal, and other ketals; ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethylbenzoate, ethyl p-dimethylbenzoate Benzoates such as esters; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methyl) benzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime) and other oxime esters; bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro -3-(1H-pyrrol-1-yl)phenyl)titanium, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrr-1-yl)ethyl)phenyl] titanocenes such as titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoine ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide and the like. The oxime ester photopolymerization initiator is not limited to those listed above, and any known and commonly used one can be used, and one type may be used alone, or two or more types may be used in combination. good.

The amount of the photopolymerization initiator (D) other than the titanocene-based photopolymerization initiator (C) is preferably 0.1 to 15 parts by weight per 100 parts by weight of the photopolymerizable monomer (B). When the content is 0.1 parts by mass or more, the resin composition has good photocurability and improved chemical resistance to plating solutions and the like. On the other hand, when the amount is 15 parts by mass or less, the effect of reducing contamination and outgassing of the plating solution is obtained, and the light absorption on the surface of the plating resist coating film is improved, and the deep-part curability is less likely to deteriorate. More preferably 0.2 to 10 parts by mass, still more preferably 0.3 to 5 parts by mass. Among them, a small amount of the oxime ester photopolymerization initiator is preferable because the above effect can be obtained. .3 to 2.0 parts by mass.

[Other additive ingredients]
The photosensitive resin composition for a plating resist of the present invention further contains a photoinitiator auxiliary, a sensitizer, a thermosetting component, a thermosetting catalyst, a cyanate compound, an elastomer, a mercapto compound, Urethane catalyst, thixotropic agent, adhesion promoter, block copolymer, chain transfer agent, polymerization inhibitor, copper damage inhibitor, antioxidant, rust inhibitor, barium sulfate, silica, talc, titanium oxide, metal oxide materials, inorganic fillers such as metal hydroxides, coloring agents such as pigments and dyes, thickeners such as finely divided silica, organic bentonite, and montmorillonite, antifoaming agents such as silicone, fluorine, and polymers, and/or Components such as leveling agents, imidazole-based, thiazole-based, triazole-based silane coupling agents, phosphinates, phosphoric acid ester derivatives, and phosphorus compounds such as phosphazene compounds can be blended. As these, those known in the field of electronic materials can be used.

The content of the coloring agent in the photosensitive resin composition is not particularly limited, but is 0.1 to 5.0 parts by mass based on 100 parts by mass of the (A) alkali-soluble resin in terms of solid content. be able to.

The photosensitive resin composition for a plating resist of the present invention can contain an organic solvent for the purpose of preparing the composition and adjusting the viscosity when applied to a substrate or film. Examples of organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether; , dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, tripropylene glycol monomethyl ether; ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbi Esters such as tall acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, and solvent naphtha; Conventional organic solvents can be used. These organic solvents may be used singly or in combination of two or more.

Volatilization drying of organic solvents is carried out by using a hot air circulating drying furnace, IR furnace, hot plate, convection oven, etc. (equipped with a heat source that heats the air using steam), and a method in which the hot air in the dryer is brought into contact with the counter current and supported by a nozzle. method of spraying on the body) can be used.

The content of the organic solvent in the photosensitive resin composition is preferably changed as appropriate according to the materials constituting the photosensitive resin composition. 50 to 300 parts by mass.

The photosensitive resin composition for plating resist of the present invention may be used as a dry film or as a liquid. Moreover, when it is used as a liquid, it may be one-liquid or two-liquid or more.

(dry film)
The photosensitive resin composition for plating resists of the present invention is in the form of a dry film comprising a support (carrier) film and a resin layer formed on the support film and made of the photosensitive resin composition for plating resists. You can also When forming a dry film, the photosensitive resin composition for a plating resist of the present invention is diluted with the above organic solvent to adjust the viscosity to an appropriate value, and is coated with a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, A film can be obtained by coating a carrier film with a uniform thickness using a transfer roll coater, gravure coater, spray coater or the like and drying at a temperature of 50 to 130° C. for 1 to 30 minutes. The coating thickness is not particularly limited, but is generally selected appropriately within the range of 1 to 150 μm, preferably 10 to 60 μm, in terms of film thickness after drying.

A plastic film is used as the support film, and it is preferable to use a plastic film such as a polyester film such as polyethylene terephthalate (PET), a polyimide film, a polyamideimide film, a polypropylene film, or a polystyrene film. The thickness of the support film is not particularly limited, but is generally selected appropriately within the range of 10 to 150 μm.

As the support film, any known one can be used without particular limitation. Examples include thermoplastic resins such as polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyimide films, polyamideimide films, polypropylene films, and polystyrene films. A film consisting of can be preferably used. Among these, a polyester film is preferable from the viewpoint of heat resistance, mechanical strength, handleability, and the like. A laminate of these films can also be used as a support film.

From the viewpoint of improving mechanical strength, the thermoplastic resin film as described above is preferably a uniaxially or biaxially stretched film.

The thickness of the support film is not particularly limited, but can be, for example, 10 μm to 150 μm.

After the resin layer of the photosensitive resin composition for plating resist of the present invention is formed on the support film, the surface of the resin layer can be peeled off for the purpose of preventing dust from adhering to the surface of the resin layer. It is preferred to laminate a protective (cover) film. As the peelable protective film, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, a surface-treated paper, or the like can be used. It is sufficient that the adhesive force between the resin layer and the protective film is smaller.

The thickness of the protective film is not particularly limited, but can be, for example, 10 μm to 150 μm.

In the present invention, the photosensitive resin composition for plating resist of the present invention is coated on the protective film and dried to form a resin layer, and a support film is laminated on the surface thereof. good. That is, as a film to which the photosensitive resin composition for plating resist of the present invention is applied when producing a dry film in the present invention, either a support film or a protective film may be used.

(cured product)
The cured product of the present invention is obtained by curing the photosensitive resin composition for a plating resist of the present invention or the resin layer of the dry film of the present invention. It has the characteristics of being highly effective in suppressing a decrease in plating deposition rate and having high releasability after plating.

(Printed wiring board)
The printed wiring board of the present invention has a cured product obtained from the photosensitive resin composition for plating resist or the resin layer of the dry film of the present invention. As a method for producing the printed wiring board of the present invention, for example, the photosensitive resin composition for plating resist of the present invention is adjusted to a viscosity suitable for the coating method using the above organic solvent, and is dipped on the substrate. After coating by a method such as coating method, flow coating method, roll coating method, bar coating method, screen printing method, curtain coating method, etc., the organic solvent contained in the composition is evaporated and dried at a temperature of 60 to 100 ° C. (temporary drying) to form a tack-free resin layer. In the case of a dry film, the resin layer is formed on the substrate by laminating it on the substrate with a laminator or the like so that the resin layer is in contact with the substrate, and then peeling off the carrier film.

Examples of the base material include printed wiring boards and flexible printed wiring boards in which a protective film such as a solder resist is formed on a circuit made of copper or the like in advance, as well as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, and glass. Copper-clad laminates made of cloth/non-woven epoxy, glass cloth/paper epoxy, synthetic fiber epoxy, etc. Copper-clad laminates made of high-frequency circuit materials such as fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide, cyanate, etc. , metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates and the like.

The lamination of the dry film onto the substrate is preferably carried out under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, when using a circuit-formed substrate, even if the surface of the circuit substrate has unevenness, the dry film adheres to the circuit substrate, so there is no entrapment of air bubbles. It also improves the ability to fill recesses on the substrate surface. The pressure condition is preferably about 0.1 to 2.0 MPa, and the heating condition is preferably 40 to 140°C.

Volatilization drying performed after coating the photosensitive resin composition for plating resist of the present invention can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. A method of contacting hot air in a dryer in a countercurrent manner and a method of blowing hot air from a nozzle onto the support can be used.

After forming a resin layer on the substrate, it is selectively exposed to active energy rays through a photomask having a predetermined pattern, and the unexposed area is treated with a dilute alkaline aqueous solution (eg, 0.3 to 3% by mass aqueous solution of sodium carbonate). to form a pattern of the cured product. In the case of a dry film, after exposure, the support film is peeled off from the dry film and developed to form a patterned cured product on the substrate. Before exposure, the support film may be peeled off from the dry film, and the exposed resin layer may be exposed and developed as long as the properties are not impaired.

The exposure machine used for the active energy ray irradiation may be any device equipped with a high-pressure mercury lamp, ultra-high pressure mercury lamp, metal halide lamp, mercury short arc lamp, etc., and irradiating ultraviolet rays in the range of 350 to 450 nm. In addition, a direct writing device (eg, a laser direct imaging device that draws an image with a laser directly from CAD data from a computer) can also be used. The lamp light source or laser light source of the direct drawing machine may have a maximum wavelength in the range of 350 to 450 nm. The amount of exposure for image formation varies depending on the film thickness and the like, but can generally be in the range of 10-1000 mJ/cm ² , preferably in the range of 20-800 mJ/cm ² .

Examples of the developing method include a dipping method, a shower method, a spray method, a brush method, and the like. Alkaline aqueous solutions such as ammonia and amines can be used.

Then, plating treatment is performed. Any of electroless nickel/gold plating, electroless nickel/palladium/gold plating, electrolytic nickel/gold plating, electroless copper plating and electrolytic copper plating can be used for the plating treatment here. Electroless nickel/gold plating or electroless nickel/palladium/gold plating is preferably used when nickel/gold plating is applied to a printed wiring board on which components are mounted at high density.

Electroless nickel/gold plating is performed under the following conditions, for example. First, degreasing, washing with water, pickling, soft etching, and washing with water are carried out in this order mainly for the purpose of cleaning the printed wiring board on which the plating resist has been cured. Next, after treating the surface with a catalyst, it is placed in a bath of a nickel plating solution at 90° C., and electroless nickel plating of about 5 μm is deposited at a plating rate of 3 to 5 minutes per 1 μm. Then, after washing with water, it is placed in a bath of gold plating solution at about 90° C., and electroless gold plating of about 0.03 μm is applied at a plating speed of 3 to 5 minutes. Here, the plating resist of the present invention has a high inhibitory effect on elution into the nickel plating solution and a decrease in plating deposition rate, and does not contaminate the plating solution.

The plating resist is then stripped using, for example, about 3% sodium hydroxide aqueous solution. Here, too, the plating resist of the present invention has high releasability after plating, and the stripping work becomes easy.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. In the following description, "parts" and "%" are based on mass unless otherwise specified.

((A) Synthesis of alkali-soluble resin A-1)
900 g of diethylene glycol dimethyl ether and t-butylperoxy 2-ethylhexanoate (perbutyl O) 21.4 g was charged, and after heating to 90° C., 309.9 g of methacrylic acid, 116.4 g of methyl methacrylate, and lactone-modified 2-hydroxyethyl methacrylate represented by general formula (I) (Daicel Chemical Industries, Ltd. ) 109.8 g of bis(4-t-butylcyclohexyl)peroxydicarbonate (perloyl TCP manufactured by NOF Corporation) was added dropwise to diethylene glycol dimethyl ether over 3 hours, followed by 6 hours. A carboxyl group-containing copolymer resin solution was obtained by aging. The reaction was performed under nitrogen atmosphere.
Next, 363.9 g of 3,4-epoxycyclohexylmethyl acrylate (Cycromer A200 manufactured by Daicel Chemical Industries, Ltd.), 3.6 g of dimethylbenzylamine, and 1.80 g of hydroquinone monomethyl ether are added to the carboxyl group-containing copolymer resin solution. , the temperature was raised to 100° C., and the ring-opening addition reaction of the epoxy was performed by stirring. After 16 hours, a solution containing 53.8% (nonvolatile matter) of a carboxyl group-containing copolymer resin having a solid content acid value of 108.9 mgKOH/g and a weight average molecular weight of 25,000 (in terms of styrene) was obtained.

(Examples 1-4 and Comparative Examples 1-3)
With respect to 100 parts by mass of (A) the alkali-soluble resin A-1 having a terminal unsaturated group synthesized above, (B) a photopolymerizable monomer, (C) a titanocene photopolymerization initiator, (D) a titanocene-based light Photopolymerization initiators excluding the polymerization initiator (C), blue pigments and dyes were blended according to the blending amounts shown in Table 1 to prepare photosensitive resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3. . In addition, all compounding amounts in Table 1 are numerical values in terms of solid matter.

For the photosensitive resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3 prepared in this manner, photocurability was evaluated by sensitivity evaluation, resolution evaluation, and electroless gold plating resistance evaluation, to nickel solution. Elution into the nickel plating solution and plating deposition rate were evaluated by the elution amount evaluation and leaching evaluation, and peelability was evaluated by the peelability evaluation. These evaluation results are also shown in Table 1.

(Sensitivity evaluation)
The photosensitive resin composition of each example and comparative example was applied to the entire surface of a flat copper substrate by screen printing so that the dry film thickness was 10 μm, and dried in a hot air circulating drying oven at 80° C. for 30 minutes. A step tablet of Stouffer T4105C was placed on the dried coating film, exposed to light with a metal halide lamp manufactured by Oak Manufacturing Co., Ltd. at 70 mJ/cm ² , and a 1% by weight sodium carbonate aqueous solution was sprayed at 30 ° C. for 90 seconds. A sensitivity evaluation substrate was produced by removing the unexposed portion. The photosensitivity of the photosensitive resin composition was evaluated by measuring the step number of the step tablet of the photocurable film formed on the sensitivity evaluation substrate. (The higher the step tablet number, the higher the photosensitivity.)

(Resolution evaluation)
The photosensitive resin composition of each example and comparative example was applied to the entire surface of a patterned copper foil substrate by screen printing so that the dry film thickness was 10 μm, and dried for 30 minutes in a hot air circulating drying oven at 80°C. minutes dried. After drying, expose to metal halide lamp 40 mJ/cm ² manufactured by Oak Manufacturing Co. through a predetermined photomask (those with lines of 30 μm to 100 μm), and spray 1% by weight aqueous sodium carbonate solution at 30° C. for 90 seconds. A resolution evaluation substrate was produced by removing the unexposed portion by. The resolution of the photosensitive resin composition was determined by visually observing the state of the lines remaining in the exposed areas of the resolution evaluation substrate. The evaluation criteria were as follows.
◯: All lines remained.
Δ: A line of 40 μm to 100 μm remained.
x: No line remained.

(Evaluation of resistance to electroless gold plating)
Each substrate prepared under the same conditions as the above resolution evaluation substrate was plated using a commercially available electroless nickel plating bath and an electroless gold plating bath under the conditions of 0.5 μm nickel and 0.03 μm gold, A gold plating resistance evaluation substrate was produced. For the gold plating resistance of the photosensitive resin composition, the photosensitive resin composition on the gold plating resistance evaluation substrate was subjected to tape peeling, and the presence or absence of peeling of the cured coating film and the presence or absence of penetration of the plating were evaluated. The evaluation criteria were as follows.
◯: There is no peeling or penetration.
Δ: Slight peeling and penetration.
x: Peeling and penetration are observed in the cured coating film.

(Evaluation of elution amount in nickel solution)
The photosensitive resin composition of each example and comparative example was applied to the entire surface of a copper plate by screen printing so that the dry film thickness was 10 μm, and dried in a hot air circulating drying oven at 80° C. for 30 minutes. After drying, the entire surface was exposed to light at 40 mJ/cm ² with a metal halide lamp manufactured by Oak Manufacturing Co., Ltd., and a 1% by mass sodium carbonate aqueous solution was sprayed at 30° C. for 90 seconds to prepare a substrate for evaluating the amount of elution. Each substrate for evaluating the amount of elution was immersed in a nickel plating solution under the conditions of 0.3 m ² /l and 90° C. for 6 hours to elute the eluted component from the coating film, thereby preparing a plating solution for elution evaluation. Each plating solution for elution evaluation was extracted with chloroform, and eluted components were quantified by GC-MS. As the elution amount increases, the plating deposition speed decreases.

(Reaching evaluation)
Using each of the plating solutions for elution evaluation described above, nickel plating is performed on a solid copper substrate under the treatment conditions of 80° C. for 30 minutes, and the thickness of the plating is measured. The thicker the plating, the less the plating deposition speed. The evaluation criteria were as follows.
A: Plating thickness of 6 μm or more.
◯: Plating thickness of 4 μm or more.
x: Plating thickness less than 4 μm.

(Peelability evaluation)
Each substrate prepared under the same conditions as the resolution evaluation substrate was immersed in a 3% sodium hydroxide aqueous solution at 50° C., and the time required for the coating film to completely peel off from the substrate of each sample was measured. The evaluation criteria were as follows.
A: Within 120 seconds.
○: Within 180 seconds.
△: Within 240 seconds.
x: more than 240 seconds.

(*1): Alkali-soluble resin A-1 synthesized by the above method
(*2): BPE-1300N manufactured by Shin-Nakamura Chemical Co., Ltd.
(*3): TMPT manufactured by Shin-Nakamura Chemical Co., Ltd.
(*4): 4G manufactured by Shin-Nakamura Chemical Co., Ltd.
(*5): Irgacure 784 manufactured by BASF Japan Ltd.
(*6): Irgacure OXE02 manufactured by BASF Japan Ltd.
(*7): Biimidazole (2,2'-bis(o-chlorophenyl)-4,5,4',5',-tetraphenyl-1,2'-biimidazole) manufactured by Kurogane Kasei Co., Ltd.
(*8): Irgacure 369 manufactured by BASF Japan Ltd.
(* 9): Irgacure TPO manufactured by BASF Japan Ltd.
(*10): B5380
(*11): Leuco Crystal Violet

According to the present invention, a highly productive photosensitive resin composition for a plating resist that has a high inhibitory effect on elution of the plating resist into the nickel plating solution and a decrease in the plating deposition rate, and has high peelability after plating treatment. , dry films and printed wiring board manufacturing methods.

Claims (6)

A photosensitive resin composition for a plating resist for nickel/gold plating on a printed wiring board on which parts are mounted,
(A) an alkali-soluble resin, (B) a photopolymerizable monomer, and (C) a titanocene-based photopolymerization initiator ,
The nickel/gold plating treatment is electroless nickel/gold plating treatment or electroless nickel/palladium/gold plating treatment,
The (A) alkali-soluble resin includes a carboxyl group-containing resin obtained by copolymerization of an unsaturated carboxylic acid and an unsaturated group-containing compound,
The (B) photopolymerizable monomer includes ethoxylated bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate and polyethylene glycol di(meth)acrylate,
The titanocene-based photopolymerization initiator (C) is bis(η5-cyclopentadienyl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium. A photosensitive resin composition for plating resists. 2. The photosensitive resin composition for a plating resist according to claim 1, further comprising (D) a photopolymerization initiator other than the titanocene-based photopolymerization initiator (C). 3. The plating resist according to claim 2, wherein the amount of the photopolymerization initiator excluding the (D) titanocene-based photopolymerization initiator (C) is 2% by mass or less with respect to the (B) photopolymerizable monomer. A photosensitive resin composition. 4. The photosensitive resin composition for a plating resist according to claim 2, wherein the (D) photopolymerization initiator other than the titanocene-based photopolymerization initiator (C) is an oxime ester-based photopolymerization initiator. thing. A dry film having a resin layer obtained by applying the photosensitive resin composition for a plating resist according to any one of claims 1 to 4 on a film and drying the composition. A step of forming a coating comprising the resin layer of the photosensitive resin composition for plating resist or dry film according to any one of claims 1 to 5 on a printed wiring board having a conductor circuit or a solder resist on the conductor circuit ,
providing a light-irradiated portion and a non-light-irradiated portion on the coating;
removing the unirradiated portion of the film with a developer to expose the conductive circuit;
After subjecting the exposed conductor circuit to nickel/gold plating treatment , removing the light-irradiated portion of the coating with a stripping solution;
A method for manufacturing a printed wiring board, comprising: