JP7229211B2 - Photosensitive resin composition - Google Patents

Description

The present invention relates to a photosensitive resin composition that can be used as a coating material, for example, an insulating coating material for coating a conductive circuit pattern formed on a substrate such as a printed wiring board, and a method for applying the photosensitive resin composition to light. The present invention relates to a cured photocured product and a substrate such as a printed wiring board coated with the photocured product.

A circuit pattern of a conductor (e.g., copper foil) is formed on a substrate such as a printed wiring board, an electronic component is mounted on the soldering land of the conductor circuit pattern by soldering, and the circuit part other than the soldering land is protected. It is covered with an insulating film (solder resist film) as a film. A cured film of a photosensitive resin composition containing a carboxyl group-containing photosensitive resin, an epoxy compound, and a photopolymerization initiator is sometimes used as the insulating coating. Further, in recent years, electronic components connected to printed wiring boards have diversified as the performance of electronic devices has improved. Therefore, printed wiring boards are sometimes required to have versatility on which various electronic components can be mounted.

In order to impart versatility to a printed wiring board, the surface of an insulating film formed on the printed wiring board is sometimes subjected to surface treatment such as gold plating. However, when the surface of the insulating coating is gold-plated, the adhesion of the insulating coating to the conductor circuit is lowered, and gold plating resistance may not be obtained in some cases.

Therefore, a photosensitive resin composition using a titanocene-based photopolymerization initiator as a photopolymerization initiator has been proposed in order to impart gold plating resistance to the insulating coating of a printed wiring board (Patent Document 1).

On the other hand, in recent years, due to the miniaturization of electronic devices, etc., there has been a demand for thin substrates such as printed wiring boards, and flexible printed wiring boards are sometimes used. For flexible printed wiring boards, the cured film of the photosensitive resin composition is required to be thin, for example, about 20 μm thick. Further, in the process of mounting electronic components on a flexible printed wiring board, a process of heat-treating at high temperature for a short period of time is frequently used in order to improve productivity.

However, when a cured film of a conventional photosensitive resin composition is subjected to heat treatment at high temperature for a short period of time in a thin state, the adhesion between the cured film and the conductor circuit is reduced, resulting in metal resistance. Plating property sometimes deteriorated. Mercaptobenzoxazole or the like has been added to the photosensitive resin composition as an adhesion-imparting agent in order to improve gold plating resistance. is applied, the adhesion between the cured film and the conductor circuit is lowered, and there is a problem that sufficient gold plating resistance may not be obtained.

WO2006/075654

In view of the above circumstances, it is an object of the present invention to provide a photosensitive resin composition capable of forming a cured product having excellent gold plating resistance without impairing various properties such as storage stability, alkali developability and heat resistance. aim.

The gist of the configuration of the present invention is as follows.
[1] (A) a carboxyl group-containing photosensitive resin, (B) a compound of cyanuric acid and a metal, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) an epoxy compound, A photosensitive resin composition comprising:
[2] Photosensitivity according to [1] containing 0.10 parts by mass or more and 14 parts by mass or less of a compound of cyanuric acid and a metal (B) with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin Resin composition.
[3] The photosensitive resin composition according to [1] or [2], wherein (B) the compound of cyanuric acid and a metal is columnar particles.
[4] Any one of [1] to [3], wherein the (B) compound of cyanuric acid and a metal has an average particle size measured by a laser method of 0.5 μm or more and 5.0 μm or less. A photosensitive resin composition.
[5] The photosensitive resin composition according to any one of [1] to [4], wherein (B) the compound of cyanuric acid and a metal is zinc cyanurate.
[6] The (A) carboxyl group-containing photosensitive resin contains (A-1) a polyfunctional epoxy resin having two or more epoxy groups in one molecule, and at least a portion of the epoxy groups are radically polymerizable unsaturated monomers. Polybasic acid-modified unsaturated monocarboxylic acid having a structure obtained by reacting a carboxylic acid to obtain an unsaturated monocarboxylic acid epoxy resin, and reacting the generated hydroxyl group with a polybasic acid and/or a polybasic acid anhydride. Epoxy resin and (A-2) a polyfunctional epoxy resin having two or more epoxy groups in one molecule and at least one linear or branched aliphatic group having 10 or more carbon atoms per carboxyl group An acid-modified long chain having a structure obtained by adding a polybasic acid and/or a polybasic acid anhydride to an unsaturated carboxylated epoxy resin which is a reaction product of a carboxylic acid and a radically polymerizable unsaturated monocarboxylic acid. The photosensitive resin composition according to any one of [1] to [5], which is at least one selected from the group consisting of hydrocarbon structure-containing epoxy resins.
[7] The photosensitive resin composition according to any one of [1] to [6], wherein the (D) reactive diluent contains a caprolactone-modified (meth)acrylate.
[8] A photocured product of the photosensitive resin composition according to any one of [1] to [7].
[9] A printed wiring board having a photocured film of the photosensitive resin composition according to any one of [1] to [7].

According to the aspect of the photosensitive resin composition of the present invention, (A) a carboxyl group-containing photosensitive resin, (B) a compound of cyanuric acid and a metal, (C) a photopolymerization initiator, and (D) a reactive A photosensitive resin containing a diluent and (E) an epoxy compound that can form a cured product with excellent gold plating resistance without impairing various properties such as storage stability, alkali developability, and heat resistance. A composition can be obtained.

According to the aspect of the photosensitive resin composition of the present invention, (B) 0.1 parts by mass or more and 14 parts by mass or less of a compound of cyanuric acid and a metal is added to 100 parts by mass of (A) the carboxyl group-containing photosensitive resin. By including it, it is possible to further improve storage stability and alkali developability while obtaining excellent gold plating resistance.

According to the aspect of the photosensitive resin composition of the present invention, (B) the compound of cyanuric acid and a metal is columnar particles, so that the gold plating resistance can be more reliably improved.

According to the aspect of the photosensitive resin composition of the present invention, the average particle size of (B) a compound of cyanuric acid and a metal measured by a laser method is 0.5 μm or more and 5.0 μm or less. It is possible to more reliably improve the property.

According to the aspect of the photosensitive resin composition of the present invention, (A) the carboxyl group-containing photosensitive resin is (A-1) a polyfunctional epoxy resin having two or more epoxy groups in one molecule. A structure obtained by reacting at least a part of the resin with a radically polymerizable unsaturated monocarboxylic acid to obtain an unsaturated monocarboxylic oxide epoxy resin, and reacting the generated hydroxyl groups with a polybasic acid and/or a polybasic acid anhydride. and/or (A-2) a polyfunctional epoxy resin having two or more epoxy groups in one molecule and having 10 or more carbon atoms per carboxyl group A polybasic acid and/or a polybasic acid anhydride is added to an unsaturated carboxylated epoxy resin which is a reaction product of at least one linear or branched aliphatic carboxylic acid and a radically polymerizable unsaturated monocarboxylic acid. By being an acid-modified long-chain hydrocarbon structure-containing epoxy resin having a structure obtained by addition, it is possible to reliably improve heat resistance and gold plating resistance.

According to the aspect of the photosensitive resin composition of the present invention, (D) the reactive diluent contains a caprolactone-modified (meth)acrylate, so that a cured product having excellent flexibility and further improved heat resistance can be obtained. can.

Next, the photosensitive resin composition of the present invention will be described in detail. The photosensitive resin composition of the present invention comprises (A) a carboxyl group-containing photosensitive resin, (B) a compound of cyanuric acid and a metal, (C) a photopolymerization initiator, (D) a reactive diluent, (E) an epoxy compound; The photosensitive resin composition of the present invention can form a cured product excellent in gold plating resistance without impairing various properties such as storage stability, alkali developability and heat resistance.

(A) Carboxyl Group-Containing Photosensitive Resin The chemical structure of the carboxyl group-containing photocurable resin is not particularly limited, and examples thereof include carboxyl group-containing resins having one or more photosensitive unsaturated double bonds. As an example of the carboxyl group-containing photosensitive resin, (A-1) a polyfunctional epoxy resin having two or more epoxy groups in one molecule is reacted with at least part of the epoxy groups with a radically polymerizable unsaturated monocarboxylic acid. to obtain an unsaturated monocarboxylic oxidized epoxy resin, and a polybasic acid-modified unsaturated monocarboxylic oxidized epoxy resin (hereinafter referred to as "A (A-2) a polyfunctional epoxy resin having two or more epoxy groups in one molecule and at least one type having 10 or more carbon atoms per carboxyl group Obtained by adding a polybasic acid and/or a polybasic acid anhydride to an unsaturated carboxylated epoxy resin which is a reaction product of a linear or branched aliphatic carboxylic acid and a radically polymerizable unsaturated monocarboxylic acid. acid-modified long-chain hydrocarbon structure-containing epoxy resin (hereinafter sometimes referred to as “A-2 resin”) having a structure such as By using the above-mentioned A-1 resin and A-2 resin, the cured product of the photosensitive resin composition can be reliably improved in heat resistance and gold plating resistance.

<A-1 resin>
The chemical structure of the polyfunctional epoxy resin is not particularly limited. rubber-modified epoxy resin, ε-caprolactone-modified epoxy resin, bisphenol A type epoxy resin, phenol novolac type epoxy resin such as bisphenol F type epoxy resin, ortho-cresol novolac type epoxy resin such as ortho-cresol novolak type, bisphenol A novolac type epoxy resin, cycloaliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, glycidylamine type polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, bisphenol-modified novolac type epoxy resin, polyfunctional modified novolak type epoxy resin, etc. can be mentioned. These polyfunctional epoxy resins may be used alone or in combination of two or more.

The epoxy equivalent of the polyfunctional epoxy resin is not particularly limited, and for example, its upper limit is preferably 3000 g/eq, more preferably 2000 g/eq, still more preferably 1000 g/eq, and particularly preferably 500 g/eq. On the other hand, the lower limit is preferably 100 g/eq, particularly preferably 200 g/eq.

Radically polymerizable unsaturated monocarboxylic acid Examples of the radically polymerizable unsaturated monocarboxylic acid include acrylic acid and/or methacrylic acid (hereinafter sometimes referred to as "(meth)acrylic acid"), crotonic acid, and tiglic acid. , angelic acid, cinnamic acid, and the like. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more.

Polybasic Acid and/or Polybasic Acid Anhydride The polybasic acid and/or polybasic acid anhydride is not particularly limited, and both saturated and unsaturated can be used. Examples of polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4- Tetrahydrophthalic acids such as ethyltetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid acids, hexahydrophthalic acids such as 4-ethylhexahydrophthalic acid, trimellitic acid, pyromellitic acid and diglycolic acid. Examples of polybasic acid anhydrides include anhydrides of the above-described polybasic acids. These compounds may be used alone or in combination of two or more.

<A-2 resin>
Polyfunctional Epoxy Resin The polyfunctional epoxy resin is not particularly limited. type epoxy resin, rubber-modified epoxy resin such as silicone-modified epoxy resin, ε-caprolactone-modified epoxy resin, phenol novolac-type epoxy resin such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, cresol novolak such as ortho-cresol novolac type type epoxy resin, bisphenol A novolac type epoxy resin, cycloaliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, glycidylamine type polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, bisphenol-modified novolak type epoxy resin, Polyfunctional modified novolac type epoxy resins and the like can be mentioned. These polyfunctional epoxy resins may be used alone or in combination of two or more. Among these, biphenyl aralkyl type epoxy resins are preferable from the viewpoint of heat resistance, gold plating resistance, flexibility and insulation reliability of the cured product of the photosensitive resin composition.

Linear or branched aliphatic carboxylic acid having 10 or more carbon atoms per carboxyl group The linear or branched aliphatic carboxylic acid having 10 or more carbon atoms per carboxyl group is a polyfunctional By reacting with the epoxy group of the epoxy resin and introducing the long-chain hydrocarbon structure derived from the aliphatic carboxylic acid into the polyfunctional epoxy resin, the heat resistance of the cured product of the photosensitive resin composition containing the photosensitive resin , gold plating resistance, flexibility, insulation reliability can be improved. Linear or branched aliphatic carboxylic acids having 10 or more carbon atoms per carboxyl group are not particularly limited, and both saturated and unsaturated carboxylic acids can be used. Examples of the aliphatic carboxylic acid include monobasic acids having 10 or more carbon atoms and dibasic acids having 20 or more carbon atoms. The acid is preferably linear or branched having two or less side chains having 2 or less carbon atoms.

In addition, the aliphatic carboxylic acid of dibasic acid introduces a long-chain hydrocarbon structure derived from the aliphatic carboxylic acid of dibasic acid into the polyfunctional epoxy resin, while different epoxy groups of the polyfunctional epoxy resin are long. They bond to each other via the above aliphatic carboxylic acid of the dibasic acid having a chain hydrocarbon structure. Therefore, the aliphatic carboxylic acid of dibasic acid is a relatively rigid skeleton of the polyfunctional epoxy resin, and the highly flexible long-chain hydrocarbon skeleton derived from the aliphatic carboxylic acid is crosslinked by a covalent bond. can be configured. As a result, the above-mentioned aliphatic carboxylic acid, which is a dibasic acid, is preferable in terms of providing the epoxy resin with a structure excellent in flexibility, heat resistance and gold plating resistance of the cured product. Furthermore, by introducing a large number of highly flexible long-chain hydrocarbon skeletons derived from the aliphatic carboxylic acid, the flexibility of the cured product can be improved. In addition to the above dibasic acid, by using together a monobasic acid having 10 or more carbon atoms per carboxyl group, the above aliphatic carboxylic acid, polyfunctional epoxy resin and ethylenically unsaturated group-containing carboxylic acid The molecular weight of the reaction product with the acid can be appropriately controlled while improving the composition ratio of the component derived from the aliphatic carboxylic acid. Thus, by appropriately adjusting the molecular weight, it is possible to improve the solubility in an alkaline developer (that is, the alkaline developability), the flexibility of the cured product, the heat resistance, and the gold plating resistance in a well-balanced manner. Become.

Carboxylic acids having 10 or more carbon atoms per carboxyl group are not particularly limited. : C12), tridecylic acid (C13), myristic acid (C14), pentadecylic acid (C15), palmitic acid (hexadecanoic acid: C16), margaric acid (heptadecanoic acid: C17), stearic acid (C18), tuberculosis stearic acid (C19), arachidic acid (C20), behenic acid (C22), tricosylic acid (C23), tetracosanoic acid (C24), hexacosanoic acid (C26), octacosanoic acid (C28), triacontanoic acid (C30), etc. .

Examples of dibasic acids include eicosanedioic acid (C20), ethyloctadecanedioic acid (C20), eicosadienedioic acid (C20), vinyl octadecanedioic acid (C20), dimethyl eicosadienedioic acid (C22), Examples include C36 dimer acids obtained by dimerization reaction of unsaturated fatty acids such as dimethyleicosanedioic acid (C22), diphenylhexadecanedioic acid (C28), and oleic acid (C18). The carboxylic acids having 10 or more carbon atoms per carboxyl group may be used alone or in combination of two or more. In addition, if necessary, a carboxylic acid having 10 or more carbon atoms per carboxyl group and a monobasic acid and/or dibasic acid having 9 or less carbon atoms per carboxyl group are used in combination. You may

The proportion of linear or branched aliphatic carboxylic acid having 10 or more carbon atoms per carboxyl group in the photosensitive resin (feeding proportion) is not particularly limited, but its lower limit depends on flexibility and 10% by mass is preferable, and 15% by mass is particularly preferable, from the viewpoint of further improving insulation reliability and adjusting the amount of polybasic acid and/or polybasic acid anhydride introduced to adjust the solid content acid value. On the other hand, the upper limit is maintained by maintaining the amount of radically polymerizable unsaturated monocarboxylic acid introduced (that is, photosensitivity), and by adjusting the amount of polybasic acid and/or polybasic acid anhydride introduced. 30% by mass is preferable, and 25% by mass is particularly preferable from the viewpoint of adjusting the acid content.

Radically polymerizable unsaturated monocarboxylic acid Examples of the radically polymerizable unsaturated monocarboxylic acid include (meth)acrylic acid, crotonic acid, tiglic acid, angelic acid, and cinnamic acid, as in the case of the A-1 resin. can. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more. The proportion of the radically polymerizable unsaturated monocarboxylic acid (feeding proportion) is not particularly limited. 2.0% by mass is preferable, and 3.0% by mass is particularly preferable from the viewpoint of adjusting the acid content. On the other hand, the upper limit is maintained at the introduction amount of carboxylic acid having 10 or more carbon atoms per carboxyl group, and the introduction amount of polybasic acid and/or polybasic acid anhydride is adjusted. 10% by mass is preferable, and 5.0% by mass is particularly preferable from the point of adjusting the solid content acid value.

Polybasic Acid and/or Polybasic Acid Anhydride Polybasic acid and/or polybasic acid anhydride undergo addition reaction with hydroxyl groups generated in the unsaturated carboxylated epoxy resin to introduce free carboxyl groups. Polybasic acid and/or polybasic acid anhydride are not particularly limited, and both saturated and unsaturated can be used. Polybasic acids include, for example, succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4- Tetrahydrophthalic acids such as ethyltetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid acids, hexahydrophthalic acids such as 4-ethylhexahydrophthalic acid, trimellitic acid, pyromellitic acid and diglycolic acid. Examples of polybasic acid anhydrides include anhydrides of the above-described polybasic acids. These compounds may be used alone or in combination of two or more. The proportion of polybasic acid and/or polybasic acid anhydride (feed proportion) is not particularly limited, but the lower limit is 7.0% by mass from the viewpoint of adjusting good alkali developability and solid content acid value. Preferably, 9.0% by weight is particularly preferred. On the other hand, the upper limit is preferably 16% by mass, particularly preferably 14% by mass, from the viewpoint of reliably preventing deterioration in insulation reliability and adjusting the solid content acid value.

(A) As the carboxyl group-containing photosensitive resin, A-1 resin or A-2 resin may be used, or A-1 resin and A-2 resin may be used in combination.

The weight average molecular weight of the carboxyl group-containing photosensitive resin is not particularly limited, but the lower limit thereof is preferably 3000, more preferably 5000, from the viewpoint of the toughness and dryness to the touch of the cured product of the photosensitive resin composition. 7000 is particularly preferred. On the other hand, the upper limit of the mass average molecular weight of the carboxyl group-containing photosensitive resin is preferably 200,000, more preferably 100,000, more preferably 50,000, from the viewpoint of preventing an increase in the viscosity of the photosensitive resin composition and obtaining excellent coatability. is particularly preferred. In addition, the "mass average molecular weight" means the mass average molecular weight measured at room temperature using gel permeation chromatography (GPC) and calculated in terms of polystyrene.

The acid value of the carboxyl group-containing photosensitive resin is not particularly limited. For example, the lower limit thereof is preferably 30 mgKOH/g, particularly preferably 40 mgKOH/g, from the viewpoint of ensuring alkali developability. On the other hand, the upper limit of the acid value of the carboxyl group-containing photosensitive resin is preferably, for example, 200 mgKOH/g from the viewpoint of preventing dissolution of the exposed portion by an alkaline developer, and ensures the moisture resistance and insulation reliability of the photocured product. 150 mgKOH/g is particularly preferable from the point of obtaining.

(B) Compound of cyanuric acid and metal By blending the compound of cyanuric acid and metal as component (B), the cured film of the photosensitive resin composition of the present invention can be cured at high temperature in a thin state.・Excellent resistance to gold plating even after short-term heat treatment. This is probably because the inclusion of the cyanuric acid and the metal compound improves the adhesion between the cured film of the photosensitive resin composition and the conductive circuit, resulting in improved gold plating resistance.

The appearance of the compound of cyanuric acid and metal is powdery. The shape of the compound of cyanuric acid and a metal is not particularly limited, but columnar particles are preferable, for example, from the viewpoint of more reliably improving gold plating resistance. The average particle size of the compound of cyanuric acid and metal is not particularly limited, but the average particle size measured by a laser method is preferably 0.5 μm or more and 5.0 μm or less in order to more reliably improve gold plating resistance. , more preferably 1.0 μm or more and 3.0 μm or less, and particularly preferably 1.3 μm or more and 2.3 μm or less. The "average particle size measured by a laser method" means an average particle size measured by a particle size distribution analyzer using a laser diffraction/scattering method. Specific examples of compounds of cyanuric acid and metals include zinc cyanurate.

The content of cyanuric acid and a metal compound (for example, zinc cyanurate) is not particularly limited, but the lower limit is 100 parts by mass of the carboxyl group-containing photosensitive resin in order to reliably improve gold plating resistance. On the other hand, 0.10 parts by mass is preferable, 0.30 parts by mass is more preferable, and 0.50 parts by mass is particularly preferable. On the other hand, the upper limit of the content of cyanuric acid and a metal compound (for example, zinc cyanurate) further improves the storage stability of the photosensitive resin composition and the alkali developability of the photocured product of the photosensitive resin composition. 30 parts by mass is preferable, 20 parts by mass is more preferable, and 14 parts by mass is particularly preferable from the viewpoint of increasing the weight.

(C) Photopolymerization initiator The photopolymerization initiator that is the component (C) is not particularly limited as long as it is commonly used. )-2-(O-benzoyloxime)], ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(0-acetyloxime), 2-( Acetyloxyiminomethyl)thioxanthen-9-one, 1,8-octanedione, 1,8-bis[9-ethyl-6-nitro-9H-carbazol-3-yl]-, 1,8-bis(O -acetyloxime), 1,8-octanedione, 1,8-bis[9-(2-ethylhexyl)-6-nitro-9H-carbazol-3-yl]-, 1,8-bis(O-acetyloxime ), (Z) -(9-ethyl-6-nitro-9H-carbazol-3-yl)(4-((1-methoxypropan-2-yl)oxy)-2-methylphenyl)methanone O-acetyloxime oxime ester photopolymerization initiators such as 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-methyl-1-(4-methylthiophenyl)-2- Examples include α-aminoalkylphenone-based photopolymerization initiators such as morpholinopropan-1-one. Examples of photopolymerization initiators other than oxime ester photopolymerization initiators and α-aminoalkylphenone photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin, benzoin methyl ether, and benzoin. ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2 -methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4 ′-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4- Dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ethyl ester and the like. These photopolymerization initiators may be used alone or in combination of two or more.

The content of the photopolymerization initiator is not particularly limited, but is preferably 1.0 parts by mass or more and 10 parts by mass or less, and 1.5 parts by mass or more and 5.0 parts by mass with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. Part or less is particularly preferred.

(D) Reactive diluent The reactive diluent as component (D) is, for example, a photopolymerizable monomer having at least one polymerizable double bond per molecule, preferably at least two polymerizable double bonds per molecule. is a compound. The reactive diluent reinforces the photocuring of the photosensitive resin composition and contributes to the formation of a photocured product having acid resistance, alkali resistance, and the like.

Examples of reactive diluents include monofunctional (meth)acrylate monomers, bifunctional (meth)acrylate monomers, and trifunctional or higher (meth)acrylate monomers. Specific examples of (meth)acrylate monomers include monofunctional (meth)acrylate monomers such as 2-hydroxyethyl methacrylate, phenoxyethyl methacrylate, diethylene glycol monomethacrylate, and 2-hydroxy-3-phenoxypropyl acrylate; ,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxy 2, such as neopentyl glycol pivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, and isocyanurate di(meth)acrylate; Functional (meth)acrylate monomers; trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth) Trifunctional ( Meth)acrylate monomers may be mentioned. A specific example of the (meth)acrylate monomer includes caprolactone-modified (meth)acrylate. These may be used alone or in combination of two or more.

As the (meth)acrylate monomer, a caprolactone-modified (meth)acrylate is preferable because it is excellent in flexibility and can give a cured product with further improved heat resistance. The caprolactone-modified (meth)acrylate is not particularly limited as long as it is a caprolactone-modified (meth)acrylate compound, and examples thereof include caprolactone-modified polyfunctional (meth)acrylates. Caprolactone-modified polyfunctional (meth)acrylates include, for example, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, pentafunctional (meth)acrylates, caprolactone-modified pentaerythritol tetra (Meth)acrylates, tetrafunctional (meth)acrylates such as caprolactone-modified ditrimethylolpropane tetra(meth)acrylate, caprolactone-modified dipentaerythritol tetra(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, caprolactone-modified trimethylol Di- or tri-functional (meth)acrylates such as propane tri(meth)acrylate, caprolactone-modified dipentaerythritol tri(meth)acrylate, and caprolactone-modified dicyclopentenyl di(meth)acrylate can be mentioned. These may be used alone or in combination of two or more.

Although the average number of repeating units of caprolactone in the caprolactone-modified (meth)acrylate is not particularly limited, it is preferably from 1 to 5, and particularly preferably from 1 to 3.

The content of the reactive diluent is not particularly limited. preferable.

(E) Epoxy compound The epoxy compound as the component (E) is used to increase the crosslink density of the cured coating film to obtain a sufficient cured coating film. Epoxy compounds include, for example, epoxy resins. Examples of epoxy resins include rubber-modified epoxy resins such as biphenylaralkyl-type epoxy resins, phenylaralkyl-type epoxy resins, biphenyl-type epoxy resins, naphthalene-type epoxy resins, dicyclopentadiene-type epoxy resins, silicone-modified epoxy resins, and ε-caprolactone. Modified epoxy resin, phenol novolak type epoxy resin such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolak type epoxy resin such as ortho-cresol novolak type, bisphenol A novolac type epoxy resin, cycloaliphatic polyfunctional epoxy resin , glycidyl ester-type polyfunctional epoxy resins, glycidylamine-type polyfunctional epoxy resins, heterocyclic polyfunctional epoxy resins, bisphenol-modified novolac-type epoxy resins, polyfunctional-modified novolak-type epoxy resins, and the like. These epoxy compounds may be used alone or in combination of two or more.

The content of the epoxy compound is not particularly limited, but is preferably 10 parts by mass or more and 80 parts by mass or less, particularly preferably 20 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the carboxyl group-containing photosensitive resin.

In addition to the components (A) to (E) described above, the photosensitive resin composition of the present invention may optionally contain various components such as colorants, matting agents, flame retardants, additives, Defoamers, fillers, non-reactive diluents and the like can be included as appropriate.

The coloring agent is not particularly limited and may be pigments, dyes, or the like. Any color such as a white colorant, a blue colorant, a green colorant, a yellow colorant, a purple colorant, a black colorant, and a red colorant can be used as the color of the colorant. Examples of the coloring agent include inorganic coloring agents such as white coloring agents such as titanium oxide (rutile-type titanium oxide and anatase-type titanium oxide), and black coloring agents such as carbon black and acetylene black. In addition, organic coloring agents such as phthalocyanine-based coloring agents such as phthalocyanine green, which is a green coloring agent, and phthalocyanine blue and lionol blue, which are blue coloring agents, can be used.

The matting agent is for imparting a matte appearance to the cured product of the photosensitive resin composition. Examples of matting agents include inorganic matting agents such as powdery silica, powdery barium sulfate and powdery alumina, and organic matting agents such as particulate urethane resins.

The flame retardant is for imparting flame retardancy to the cured product of the photosensitive resin composition. Examples of flame retardants include phosphorus-based flame retardants. Phosphorus-based flame retardants include, for example, tris(chloroethyl) phosphate, tris(2,3-dichloropropyl) phosphate, tris(2-chloropropyl) phosphate, tris(2,3-bromopropyl) phosphate, tris(bromo Halogen-containing phosphoric acid such as chloropropyl)phosphate, 2,3-dibromopropyl-2,3-chloropropylphosphate, tris(tribromophenyl)phosphate, tris(dibromophenyl)phosphate, tris(tribromoneopentyl)phosphate Esters; non-halogen aliphatic phosphates such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate; triphenyl phosphate, cresyldiphenyl phosphate, dicresylphenyl phosphate, tricresyl phosphate, trixyl Nyl phosphate, xylenyl diphenyl phosphate, tris(isopropylphenyl) phosphate, isopropylphenyl diphenyl phosphate, diisopropylphenyl phosphate, tris(trimethylphenyl) phosphate, tris(t-butylphenyl) phosphate, hydroxyphenyldiphenyl phosphate, octyldiphenyl phosphate Non-halogenated aromatic phosphates such as aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, bisdiethyl Metal salts of phosphinic acids such as titanyl phosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, titanium tetrakisdiphenylphosphinate, 9,10-dihydro-9 Phosphine oxide compounds such as -oxa-10-phosphaphenanthrene-10-oxide, diphenylvinylphosphine oxide, triphenylphosphine oxide, trialkylphosphine oxide and tris(hydroxyalkyl)phosphine oxide. Among these, organic phosphate-based flame retardants are preferred.

Additives include dicyandiamide (DICY) and its derivatives, melamine and its derivatives, boron trifluoride-amine complex, organic acid hydrazide, diaminomaleonitrile (DAMN) and its derivatives, guanamine and its derivatives, amine imide (AI), etc. can be mentioned.

Examples of antifoaming agents include silicone-based, hydrocarbon-based, and acrylic polymer-based. Examples of fillers include talc, aluminum hydroxide, and mica.

The non-reactive diluent is used to adjust the viscosity, drying properties, coatability, etc. of the photosensitive resin composition. Examples of non-reactive diluents include organic solvents. Examples of organic solvents include ketones such as methyl ethyl ketone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, n-propanol, isopropanol and cyclohexanol, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane. cellosolves such as cellosolve, butyl cellosolve, carbitol, carbitols such as butyl carbitol, ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, diethylene glycol monomethyl ether acetate, ethyl diethylene glycol Examples include esters such as glycol acetate. These may be used alone or in combination of two or more.

The method for producing the photosensitive resin composition of the present invention described above is not limited to a specific method. Mixing and kneading means such as rolls, ball mills, sand mills, bead mills and kneaders, or stirring and mixing means such as super mixers, planetary mixers and trimixes can be used for kneading or mixing. Further, if necessary, pre-kneading or pre-mixing may be performed before kneading or mixing.

Next, an example of how to use the photosensitive resin composition of the present invention will be described. Here, the method of coating the photosensitive resin composition of the present invention on a printed wiring board (here, a flexible printed wiring board) to form an insulating film such as a solder resist film on the flexible printed wiring board is exemplified. will be explained.

A flexible printed wiring board is coated with the photosensitive resin composition of the present invention produced as described above in a desired thickness (for example, a thickness of 5 to 30 μm). Any known means can be used as the coating means, and examples thereof include screen printing, bar coater, spray coating, applicator, blade coater, knife coater, roll coater, gravure coater and the like. After coating the photosensitive resin composition, if necessary, the photosensitive resin composition is pre-dried with a heating device (for example, a hot air oven, a far-infrared oven, etc.), and the non-reactive diluent is removed from the photosensitive resin composition. is volatilized to make the surface of the coating film tack-free. Pre-drying conditions include, for example, a drying temperature of 60° C. to 90° C. and a drying time of 10 minutes to 60 minutes. After pre-drying, a negative film having a translucent pattern other than the lands of the circuit pattern is adhered to the coated photosensitive resin composition, and ultraviolet rays (for example, wavelengths of 300 to 400 nm) are irradiated from above the negative film. Then, the coating film of the photosensitive resin composition is photocured to form a photocured product. Next, the photocured product, which is the coating film, is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. For example, a spray method, a shower method, or the like is used as the developing method, and a 0.5 to 5% by mass sodium carbonate aqueous solution can be used as the dilute alkaline aqueous solution. Next, the coating film after development is subjected to a heat curing treatment (post cure) at 120 ° C to 180 ° C for 20 minutes to 80 minutes with a heating device (for example, a hot air circulation dryer, etc.) to make it flexible. An insulating film (solder resist film) having a desired pattern can be formed on the printed wiring board.

Examples of the present invention will now be described, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

Examples 1-7, Comparative Examples 1-3
Each component shown in Table 1 below was blended in the mixing ratio shown in Table 1 below, mixed and dispersed at room temperature using a three-roll, and used in Examples 1 to 7 and Comparative Examples 1 to 3. A flexible resin composition was prepared. Then, the prepared photosensitive resin composition was applied as follows to prepare a test sample. The numbers of the compounding amounts in Table 1 below indicate parts by mass unless otherwise specified. In addition, a blank column in Table 1 below means no compounding.

(A) Carboxyl group-containing photosensitive resin/synthetic resin A
In a 500 mL separable flask equipped with a stirrer and a reflux condenser, 86.45 g of diethylene glycol monoethyl ether acetate (hereinafter "EDGAC") and 8-ethyloctadecanedioic acid (Okamura Oil Co., Ltd.) are placed under a nitrogen/air (2:1) atmosphere. Co., Ltd., SB-20) 26.54 g (6.3 parts by mass), behenic acid 45.35 g (10.7 parts by mass), stearic acid 9.71 g (2.3 parts by mass), acrylic acid 14.36 g ( 3.4 parts by mass), 0.65 g (0.1 parts by mass) of triphenylphosphine (TPP), and 0.43 g (0.1 parts by mass) of methoxyhydroquinone (MEHQ) were charged, and nitrogen/air ( 2:1) was blown in at 0.3 mL/sec, and the mixture was heated and stirred at 110° C. until dissolved. Separately, 137.65 g (32.6 parts by mass) of biphenyl aralkyl type epoxy resin (Nippon Kayaku Co., Ltd., NC-3000, epoxy equivalent 265 to 285 g/eq) was heated to 80°C in 59.8 g of EDGAC solvent. The mixture was uniformly dissolved and charged into the flask, heated and stirred at 115° C. for 15 to 17 hours, and reacted until the acid value of the reaction solution became 6 mgKOH/g or less. 42.23 g (9.9 parts by mass) of hydrogenated trimellitic anhydride (Mitsubishi Gas Chemical Co., Ltd., HTMAn) was further added to the reactant, and the mixture was stirred at 100° C. for 2 to 3 hours in an air atmosphere. It was confirmed by FT-IR (infrared spectrophotometer) that the acid anhydride had disappeared. As a result, a synthetic resin A having a solid content (resin content) of 65% by mass and an acid value of 85 mgKOH/g shown in Table 1 below was obtained.

・SP-4621: A polybasic acid-modified epoxy having a structure obtained by reacting at least part of the epoxy groups of a cresol novolac epoxy resin with acrylic acid to obtain an epoxy acrylate, and reacting the resulting hydroxyl groups with a polybasic acid. Acrylate, solid content (resin content) 65% by mass, Showa Denko K.K.
・ZAR-2000: A polybasic acid-modified epoxy having a structure obtained by reacting at least part of the epoxy groups of a bisphenol F type epoxy resin with acrylic acid to obtain an epoxy acrylate, and reacting the resulting hydroxyl groups with a polybasic acid. Acrylate, solid content (resin content) 65% by mass, Nippon Kayaku Co., Ltd.
・ZCR-1569H: A polybasic acid-modified epoxy acrylate having a structure obtained by reacting at least part of the epoxy groups of a biphenyl-type epoxy resin with acrylic acid to obtain an epoxy acrylate, and reacting the resulting hydroxyl groups with a polybasic acid. , Solid content (resin content) 65% by mass, Nippon Kayaku Co., Ltd.

(B) Compound of cyanuric acid and metal Starfine F-10: Zinc cyanurate, average particle size measured by laser method: 1.7 μm, columnar particles, Nissan Chemical Industries.

(C) photopolymerization initiator NCI-831: (9-ethyl-6-nitro-9H-carbazol-3-yl) (4-((1-methoxypropan-2-yl)oxy)-2-methylphenyl ) methanone O-acetyloxime (oxime-based photopolymerization initiator), ADEKA Corporation.
- Omnirad 369: 2-benzyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone (α-aminoalkylphenone photoinitiator), IGM Resins B.I. V. Company.

(D) Reactive diluent DPCA-60: Nippon Kayaku Co., Ltd.
(E) Epoxy compound YX-4000HK: Mitsubishi Chemical Corporation.

Colorant, Lionol Blue FG-7351: Toyo Ink Mfg. Co., Ltd.
- MA14: Mitsubishi Chemical Corporation.
Matting agent, Acemat OK-412: Evonik.
・RHC-730: Dainichiseika Kogyo Co., Ltd.
Flame retardant Exolit OP-935: Clariant Japan.
Additives and melamine: Nissan Chemical Co., Ltd.
・DICY-7: Mitsubishi Chemical Corporation.
Defoamer KS-66: Shin-Etsu Chemical Co., Ltd.
Non-reactive diluent EDGAC: Sanyo Kaseihin Co., Ltd.

Adhesion imparting agent 2MBO: Conventional adhesion imparting agent, Aldrich Chemical Company.

Test specimen preparation process Flexible printed wiring in which a comb-shaped circuit pattern with a conductor (copper foil) thickness of 18 μm, a line width of 100 μm, and a space width of 100 μm is provided on a 25 μm-thick polyimide film (“Kapton 100H” by Toray DuPont Co., Ltd.). The plate was surface-treated with a 3% by mass sulfuric acid aqueous solution, and then the photosensitive resin composition prepared as described above was applied by screen printing so that the DRY film thickness on the conductor was 20 μm. After that, pre-drying was performed at 70° C. for 20 minutes in a BOX furnace. After pre-drying, a negative film (photomask) having a pattern other than the land of the circuit pattern that is translucent is brought into close contact with the applied photosensitive resin composition, and an exposure device (Oak Manufacturing Co., Ltd., "HMW-680GW ”) was irradiated with ultraviolet rays (wavelength: 300 to 400 nm) at 400 mJ/cm ² . After the ultraviolet irradiation, development was carried out for 60 seconds using a 1% by mass sodium carbonate aqueous solution at 30° C. and a spray pressure of 0.1 MPa. After the development, a heat curing treatment (post cure) was performed at 150° C. for 60 minutes in a BOX furnace to form a cured coating film, and a test sample for evaluation was produced.

Evaluation items are as follows.
(1) Gold Plating Resistance Using commercially available electroless nickel plating baths and electroless gold plating baths, plating was performed under conditions of 5 μm nickel and 0.03 μm gold. After evaluating the presence or absence of peeling of the cured coating film and the presence or absence of penetration of the plating, the presence or absence of peeling of the cured coating film from the substrate was evaluated by tape peeling. Judgment criteria are as follows.
⊚: After tape peeling, the cured coating film is not peeled at all.
◯: The cured coating film was slightly peeled after tape peeling.
Δ: Slight penetration after plating.
x: After plating, the cured coating film was peeled off.

(2) Storage stability (thickening rate)
The viscosity of the photosensitive resin composition prepared as described above was measured with a tuning fork vibrating viscometer (25° C.), and the viscosity increase rate after 7 days at 50° C. in a constant temperature bath was determined. Judgment criteria are as follows.
○: Less than 10% thickening rate △: 10% to less than 20% thickening rate ×: 20% or more thickening rate

(3) Alkali developability The time required to develop the coating film after predrying in the test sample preparation process at a spray pressure of 0.2 MPa (30 ° C., using a 1% by mass sodium carbonate developer) was set as a breakpoint, and the time was measured. Judgment criteria are as follows.
○: Break point less than 30 seconds △: Break point 30 seconds or more and less than 60 seconds ×: Break point 60 seconds or more

(4) Heat resistance After immersing the cured coating film of the gold-plated specimen in a solder bath at 260°C for 30 seconds according to the test method of JIS C-6481, a peeling test with cellophane tape was used as one cycle. The state of the cured coating film after repeating the two times was visually observed and evaluated according to the following criteria.
◯: No abnormality is observed in the cured coating film after repeating the two cycles.
x: Abnormalities such as peeling are observed in the cured coating film after repeating 2 cycles.

The evaluation results are shown in Table 1 below.

As shown in Table 1 above, (A) a carboxyl group-containing photosensitive resin, (B) a compound of cyanuric acid and a metal (zinc cyanurate in the examples), (C) a photopolymerization initiator, and (D ) In the photosensitive resin compositions of Examples 1 to 7 containing a reactive diluent and (E) an epoxy compound, even if the DRY film thickness is as thin as 20 μm, gold plating resistance and heat resistance are improved. In addition, the storage stability of the photosensitive resin composition and the alkali developability of the photocured product of the photosensitive resin composition were also excellent. In particular, from Examples 1 to 3 and Example 7, when about 0.5 parts by mass or more and about 10 parts by mass or less of zinc cyanurate is included with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, the carboxyl group-containing photosensitive resin Storage stability and alkali developability were further improved as compared with the case where about 15 parts by mass of zinc cyanurate was contained with respect to 100 parts by mass.

On the other hand, as shown in Table 1 above, in Comparative Examples 1 and 3 in which zinc cyanurate was not blended, when the DRY film thickness was reduced to 20 μm, good gold plating resistance was not obtained. In addition, in Comparative Example 2 in which mercaptobenzoxazole, which is a conventional adhesion imparting agent, was used instead of zinc cyanurate, when the DRY film thickness was reduced to 20 μm, good gold plating resistance, heat resistance and Alkaline developability was not obtained.

In the present invention, it is possible to obtain a photosensitive resin composition capable of forming a cured product having excellent gold plating resistance without impairing basic properties such as storage stability, alkali developability and heat resistance. It has high utility value in the field of printed wiring boards on which electronic components are mounted.

Claims (8)

(A) a carboxyl group-containing photosensitive resin, (B) a compound of cyanuric acid and a metal, (C) a photopolymerization initiator, (D) a reactive diluent, and (E) an epoxy compound ,
The photosensitive resin composition (B) wherein the compound of cyanuric acid and a metal is zinc cyanurate . The photosensitive resin composition according to claim 1, wherein the (B) compound of cyanuric acid and a metal is contained in an amount of 0.10 parts by mass or more and 14 parts by mass or less relative to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. . 3. The photosensitive resin composition according to claim 1, wherein the (B) compound of cyanuric acid and a metal is columnar particles. The photosensitive resin composition according to any one of claims 1 to 3, wherein (B) the compound of cyanuric acid and a metal has an average particle size measured by a laser method of 0.5 µm or more and 5.0 µm or less. . The (A) carboxyl group-containing photosensitive resin is (A-1) a polyfunctional epoxy resin having two or more epoxy groups in one molecule, and at least a portion of the epoxy groups contain a radically polymerizable unsaturated monocarboxylic acid. Polybasic acid-modified unsaturated monocarboxylic acid epoxy resin having a structure obtained by reacting to obtain an unsaturated monocarboxylic acid epoxy resin, and reacting the generated hydroxyl group with a polybasic acid and/or a polybasic acid anhydride; and (A-2) a polyfunctional epoxy resin having two or more epoxy groups in one molecule and at least one linear or branched aliphatic carboxylic acid having 10 or more carbon atoms per carboxyl group; An acid-modified long-chain hydrocarbon structure having a structure obtained by adding a polybasic acid and/or a polybasic acid anhydride to an unsaturated carboxylated epoxy resin that is a reaction product with a radically polymerizable unsaturated monocarboxylic acid. 5. The photosensitive resin composition according to any one of claims 1 to 4 , which contains at least one selected from the group consisting of epoxy resins. 6. The photosensitive resin composition according to any one of claims 1 to 5 , wherein the (D) reactive diluent contains a caprolactone-modified (meth)acrylate. A photocured product of the photosensitive resin composition according to any one of claims 1 to 6 . A printed wiring board comprising a photocured film of the photosensitive resin composition according to any one of claims 1 to 6 .