JP2019056867A - Photosensitive resin composition - Google Patents

Abstract

To provide a photosensitive resin composition capable of giving a cured product excellent in flexibility and heat resistance, especially solder heat resistance at a high temperature of 350°C or higher.SOLUTION: The photosensitive resin composition contains (A) a carboxyl group-containing photosensitive resin, (B) a reactive diluent, (C) a photopolymerization initiator, and (D) an epoxy compound. The amount of a carboxyl group-containing photosensitive resin having a urethane bond contained in the carboxyl group-containing photosensitive resin (A) is 10 mass% or less. The reactive diluent (B) is a compound containing a caprolactone-modified (meth)acrylate and having no urethane bond.SELECTED DRAWING: None

Description

  The present invention relates to a photosensitive resin composition capable of obtaining a cured product excellent in flexibility and heat resistance.

  A printed wiring board is used to form a pattern of a conductor circuit on a board, and to mount electronic components on the soldering land of the pattern by soldering. The circuit portion excluding the soldering land is made of a photocured film. It may be covered with a certain insulating film. This prevents solder from adhering to unnecessary parts when soldering electronic components to a printed wiring board, and prevents circuit conductors from being directly exposed to air and being corroded by oxidation or humidity. To do.

  The printed wiring board includes a printed wiring board using a rigid board, a printed wiring board using a flexible board, and the like. In particular, in a printed wiring board (flexible printed wiring board) using a flexible substrate, the insulating coating is required to have not only heat resistance such as solder heat resistance but also flexibility (flexibility) and low warpage.

  Therefore, for example, (A) carboxyl group-containing resin, (B) urethane (meth) acrylate having 6 or more functional groups of (meth) acrylate, (C) photopolymerization initiator, and (D) titanium oxide A photosensitive resin composition has been proposed (Patent Document 1). Patent Document 1 discloses that when a urethane (meth) acrylate having 6 or more functional groups of (meth) acrylate is blended, that is, by blending a compound having a urethane bond, the bendability of the photocured film (at the time of folding) It is a photosensitive resin composition that improves the prevention of cracking).

  However, in Patent Document 1 in which a compound having a urethane bond is added in order to impart flexibility, there is a problem that the heat resistance of the photocured film, in particular, the solder heat resistance at a high temperature of 350 ° C. or higher may not be sufficient. there were.

JP2015-206992A

  In view of the above circumstances, an object of the present invention is to provide a photosensitive resin composition capable of obtaining a cured product excellent in flexibility and heat resistance, in particular, solder heat resistance at a high temperature of 350 ° C. or higher.

  An aspect of the present invention is a photosensitive resin composition containing (A) a carboxyl group-containing photosensitive resin, (B) a reactive diluent, (C) a photopolymerization initiator, and (D) an epoxy compound. And (A) the carboxyl group-containing photosensitive resin having a urethane bond contained in the carboxyl group-containing photosensitive resin is 10% by mass or less, and (B) the reactive diluent is a caprolactone modified (meta ) A photosensitive resin composition characterized by being a compound containing an acrylate and having no urethane bond.

  In the above aspect, the reactive diluent (B) contains caprolactone-modified (meth) acrylate as a blending component, but does not contain a compound having a urethane bond. Therefore, caprolactone-modified (meth) acrylate is a chemical structure having no urethane bond.

  An aspect of the present invention is the photosensitive resin composition, wherein the (A) carboxyl group-containing photosensitive resin is a resin having no urethane bond.

  An aspect of the present invention is a photosensitive resin composition, wherein the caprolactone-modified (meth) acrylate has an average number of repeating units of caprolactone of 2 or more.

  An aspect of the present invention is a photosensitive resin composition, wherein the caprolactone-modified (meth) acrylate is a pentafunctional or higher functional caprolactone-modified (meth) acrylate.

  An aspect of the present invention is the photosensitive resin composition, wherein the caprolactone-modified (meth) acrylate is contained in an amount of 20 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. It is.

  The aspect of this invention is the photocured material of the said photosensitive resin composition.

  The aspect of this invention is a printed wiring board which has the photocured film of the said photosensitive resin composition.

  According to the aspect of the present invention, the carboxyl group-containing photosensitive resin having a urethane bond contained in the carboxyl group-containing photosensitive resin is 10% by mass or less, and contains caprolactone-modified (meth) acrylate as a reactive diluent. However, by using a reactive diluent that does not contain a compound having a urethane bond, it has excellent flexibility and heat resistance, in particular, curing excellent in solder heat resistance at a high temperature of 350 ° C. or higher. You can get things.

  According to the aspect of the present invention, the carboxyl group-containing photosensitive resin is a resin that does not have a urethane bond, that is, it does not include a resin having a urethane bond. Solder heat resistance can be obtained more reliably.

  According to the aspect of the present invention, when the average number of repeating units of caprolactone in caprolactone-modified (meth) acrylate is 2 or more, the flexibility of the cured product can be further improved.

  According to the aspect of the present invention, the caprolactone-modified (meth) acrylate is a pentafunctional or higher functional caprolactone-modified (meth) acrylate, so that the solder heat resistance of the cured product can be reliably improved.

  According to the aspect of the present invention, the flexibility of the cured product is further improved by including 20 parts by mass or more and 100 parts by mass or less of caprolactone-modified (meth) acrylate with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin. be able to.

  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 reactive diluent, (C) a photopolymerization initiator, and (D) an epoxy compound. The carboxyl group-containing photosensitive resin having a urethane bond contained in the (A) carboxyl group-containing photosensitive resin is 10% by mass or less, and the (B) reactive diluent is It is a compound containing caprolactone-modified (meth) acrylate and having no urethane bond.

(A) Carboxyl group-containing photosensitive resin The carboxyl group-containing photosensitive resin having no urethane bond used as the carboxyl group-containing photosensitive resin is not particularly limited. For example, 1 is a photosensitive unsaturated double bond. Examples thereof include resins having at least one. Examples of the carboxyl group-containing photosensitive resin having no urethane bond include acrylic acid and methacrylic acid (hereinafter referred to as “the epoxy group”) in at least part of the epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in one molecule. (Meth) acrylic acid ”)) and other radical polymerizable unsaturated monocarboxylic acids were reacted to obtain radical polymerizable unsaturated monocarboxylic oxide epoxy resins such as epoxy (meth) acrylate. Mention may be made of polybasic acid-modified radically polymerizable unsaturated monocarboxylic oxide epoxy resins such as polybasic acid-modified epoxy (meth) acrylate obtained by reacting a hydroxyl group with a polybasic acid or its anhydride.

  Any polyfunctional epoxy resin can be used as long as it is a bifunctional or higher functional epoxy resin. The epoxy equivalent of the polyfunctional epoxy resin is not particularly limited, but the upper limit is preferably 3000 g / eq, more preferably 2000 g / eq, further 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.

  Polyfunctional epoxy resins include, for example, biphenyl aralkyl type epoxy resins, phenyl aralkyl type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, rubber modified epoxy resins such as silicone modified epoxy resins, ε-caprolactone modified epoxy resin, phenol novolac type epoxy resin such as bisphenol A type, bisphenol F type, bisphenol AD type, cresol novolac type epoxy resin such as о-cresol novolac type, bisphenol A novolac type epoxy resin, cycloaliphatic poly Functional epoxy resin, glycidyl ester type polyfunctional epoxy resin, glycidylamine type polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, bisphenol-modified novolac type epoxy resin, A polyfunctional modified novolac type epoxy resin, a condensate type epoxy resin of a phenol and an aromatic aldehyde having a phenolic hydroxyl group can be exemplified. Moreover, you may use what introduce | transduced halogen atoms, such as Br and Cl, into these resin. These epoxy resins may be used alone or in combination of two or more.

  The radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and acrylic acid and methacrylic acid are preferable. These radically polymerizable unsaturated monocarboxylic acids may be used alone or in combination of two or more.

  The reaction method of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is not particularly limited. For example, the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid are reacted by heating in an appropriate diluent. Can do.

  The polybasic acid or polybasic acid anhydride is for reacting with a hydroxyl group produced by the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid to introduce a free carboxyl group into the resin. The polybasic acid or its anhydride is not particularly limited, and either saturated or 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- Ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydro Examples include phthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, trimellitic acid, pyromellitic acid, and diglycolic acid. Examples of polybasic acid anhydrides include these anhydrides. These compounds may be used alone or in combination of two or more.

  In the present invention, the above-mentioned polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin can also be used as a carboxyl group-containing photosensitive resin having no urethane bond. By reacting the carboxyl group of the oxidized epoxy resin with a glycidyl compound having one or more radically polymerizable unsaturated groups and an epoxy group, radically polymerizable unsaturated groups were further introduced to further improve the photosensitivity. Alternatively, a carboxyl group-containing photosensitive resin having no urethane bond may be used.

  The photosensitivity-improved carboxyl group-containing photosensitive resin having no urethane bond is obtained by reacting the glycidyl compound with a radical polymerizable unsaturated group having a polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin skeleton. Therefore, the photopolymerization reactivity is further improved, and more excellent photosensitive characteristics can be exhibited. Examples of the compound having one or more radically polymerizable unsaturated groups and an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, pentaerythritol triacrylate monoglycidyl ether, pentaerythritol trimethacrylate monoglycidyl ether, and the like. Can be mentioned. In addition, you may have multiple glycidyl groups in 1 molecule. The above-mentioned compound having one or more radically polymerizable unsaturated groups and an epoxy group may be used alone or in combination of two or more.

  As the carboxyl group-containing photosensitive resin, the carboxyl group-containing photosensitive resin having a urethane bond in the carboxyl group-containing photosensitive resin from the viewpoint of more reliably obtaining heat resistance, particularly solder heat resistance at a high temperature of 350 ° C. or higher. The content of is 10% by mass or less (that is, the above-described carboxyl group-containing photosensitive resin having no urethane bond is 90% by mass or more), and is composed of the above-described carboxyl group-containing photosensitive resin having no urethane bond. (That is, the content of the carboxyl group-containing photosensitive resin having a urethane bond in the carboxyl group-containing photosensitive resin is 0% by mass, and the carboxyl group-containing photosensitive resin having no urethane bond is 100% by mass) Is particularly preferred. Accordingly, a carboxyl group-containing photosensitive resin that does not contain a resin having a urethane bond, such as an acid-modified urethanized unsaturated monocarboxylic oxide epoxy resin such as an acid-modified urethanized epoxy (meth) acrylate resin, is particularly preferable.

  The acid value of the carboxyl group-containing photosensitive resin is not particularly limited, but the lower limit is preferably 30 mgKOH / g, particularly preferably 40 mgKOH / g, from the viewpoint of reliable alkali development. On the other hand, the upper limit of the acid value is preferably 200 mgKOH / g from the viewpoint of preventing dissolution of the exposed area with an alkali developer, and particularly preferably 150 mgKOH / g from the viewpoint of preventing moisture resistance of the cured product and preventing deterioration of electrical characteristics.

  Further, the mass average molecular weight of the carboxyl group-containing photosensitive resin is not particularly limited, but the lower limit is preferably 3000 and particularly preferably 5000 from the viewpoint of toughness of the cured product and dryness to touch. On the other hand, the upper limit of the mass average molecular weight is preferably 200,000, particularly preferably 50,000 from the viewpoint of obtaining a smooth alkali developability by introducing a predetermined proportion of carboxyl groups.

  The carboxyl group-containing photosensitive resin having no urethane bond may be synthesized in the reaction step using the above raw materials, and a commercially available carboxyl group-containing photosensitive resin having no urethane bond is used. May be. Examples of commercially available carboxyl group-containing photosensitive resins having no urethane bond include "SP-4621" (Showa Denko KK), "ZAR-2000", "ZCR-1569H" Medicinal Co., Ltd.), “Cyclomer P (ACA) Z-250” (Daicel Ornex Co., Ltd.) and the like. These resins may be used alone or in combination of two or more.

(B) Reactive Diluent A reactive diluent is, for example, a photopolymerizable monomer such as a (meth) acrylate monomer, and has at least one polymerizable double bond per molecule, preferably at least two per molecule. It is a compound which has this. In the photosensitive resin composition of the present invention, a caprolactone-modified (meth) acrylate monomer having a chemical structure having no urethane bond is blended as a reactive diluent, and a compound having a urethane bond is not blended. As a reactive diluent, the above-mentioned caprolactone-modified (meth) acrylate is blended, and a compound having a urethane bond is not blended, so that it has excellent flexibility and heat resistance, particularly solder heat resistance at a high temperature of 350 ° C. or higher. It is possible to obtain an excellent cured product.

  The caprolactone-modified (meth) acrylate is not particularly limited as long as it is a caprolactone-modified product of a (meth) acrylate compound, and examples thereof include caprolactone-modified polyfunctional (meth) acrylate. Examples of the caprolactone-modified polyfunctional (meth) acrylate include five or more functional (meth) acrylates such as caprolactone-modified dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol penta (meth) acrylate, and caprolactone-modified pentaerythritol tetra. Tetrafunctional (meth) acrylates such as (meth) acrylate, caprolactone-modified ditrimethylolpropane tetra (meth) acrylate, caprolactone-modified dipentaerythritol tetra (meth) acrylate, caprolactone-modified pentaerythritol tri (meth) acrylate, caprolactone-modified trimethylol Propanetri (meth) acrylate, caprolactone-modified dipentaerythritol tri (meth) acrylate, 2-3-functional (meth) acrylates such as caprolactone-modified dicyclopentenyl di (meth) acrylate. These may be used alone or in combination of two or more.

  Among these, from the viewpoint of reliably improving the solder heat resistance, pentafunctional or higher caprolactone-modified (meth) acrylate is preferable, hexafunctional caprolactone-modified (meth) acrylate is more preferable, and caprolactone-modified dipentaerythritol hexa (meth). Acrylate is particularly preferred.

  The average number of repeating units of caprolactone in the caprolactone-modified (meth) acrylate is not particularly limited, but is preferably 2 or more and 5 or less, and particularly preferably 2 or more and 3 or less from the viewpoint of further improving flexibility.

  The content of the caprolactone-modified (meth) acrylate is not particularly limited, but the lower limit is 100 parts by weight of a carboxyl group-containing photosensitive resin (solid content (resin content), hereinafter the same) from the viewpoint of further improving flexibility. ) Is preferably 10 parts by mass, more preferably 20 parts by mass, and particularly preferably 25 parts by mass. On the other hand, the upper limit is preferably 100 parts by weight, and 50 parts by weight with respect to 100 parts by weight of the carboxyl group-containing photosensitive resin, from the viewpoint of more reliably forming a tack-free coating film by performing preliminary drying. Is particularly preferred.

  In the present invention, in addition to the caprolactone-modified (meth) acrylate, in addition to the caprolactone-modified (meth) acrylate, a chemical structure that does not have a urethane bond and a (meth) acrylate compound that is not modified with caprolactone are used in combination. May be.

  The (meth) acrylate compound not modified with caprolactone, which has a chemical structure not having a urethane bond, is not particularly limited. For example, 2-hydroxyethyl methacrylate, phenoxyethyl methacrylate, diethylene glycol monomethacrylate, 2 -Hydroxy-3-phenoxypropyl acrylate, 1,4-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, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, ethylene oxide modified diphosphate (Meth) acrylate, allylated cyclohexyl di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, penta Examples include erythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, propionic acid-modified dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. These may be used alone or in combination of two or more.

  The content of the reactive diluent is not particularly limited, but the lower limit is preferably 10 parts by weight, more preferably 20 parts by weight, and particularly preferably 25 parts by weight with respect to 100 parts by weight of the carboxyl group-containing photosensitive resin. preferable. On the other hand, 100 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 50 mass parts is especially preferable as the upper limit.

(C) Photopolymerization initiator Although it does not specifically limit as a photoinitiator, For example, an oxime ester system photoinitiator can be mentioned. The oxime ester photopolymerization initiator is a compound having an oxime ester group. Examples of the oxime ester photopolymerization initiator include 1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)], and 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- Tokishipuropan 2-yl) oxy) -2-methylphenyl) can be exemplified methanone O- acetyl oxime. These compounds may be used alone or in combination of two or more.

  The photopolymerization initiator other than the above oxime ester photopolymerization initiator is not particularly limited. For example, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, benzoin, benzoin methyl ether, 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-methyl-4 '-( Methylthio) -2-morpholinopropiophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-hydroxy-2-methyl-1-phenylpropane-1-o 1-hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2, -Methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, Examples include benzyl dimethyl ketal, acetophenone dimethyl ketal, and P-dimethylaminobenzoic acid ethyl ester. These may be used alone or in combination of two or more.

  Although content of a photoinitiator is not specifically limited, 1.0-10 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 2.0-8.0 mass parts is especially preferable.

(D) Epoxy compound An epoxy compound is for raising the crosslinking density of a cured coating film, and obtaining sufficient cured coating film, for example, adds an epoxy resin. Examples of the epoxy resin include biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, bisphenol A type epoxy resin, novolak type epoxy resin (phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type). Bisphenol F type and bisphenol S type epoxy resin obtained by reacting bisphenol F and bisphenol S with epichlorohydrin, and alicyclic epoxy resin having cyclohexene oxide group, tricyclodecane oxide group, cyclopentene oxide group, etc. A dicyclopentadiene type epoxy resin, an adamantane type epoxy resin, etc. can be mentioned. These compounds may be used alone or in combination of two or more.

  Although content of an epoxy compound is not specifically limited, 10-100 mass parts is preferable with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 20-60 mass parts is especially preferable.

  In the photosensitive resin composition of the present invention, in addition to the components (A) to (D) described above, various components, for example, a compound that forms a complex with copper, a colorant, and a flame retardant, as necessary. Various additives (for example, curing catalysts, extender pigments, antifoaming agents, organic fillers, etc.), non-reactive diluents, and the like can be appropriately contained.

Compound that forms a complex with copper By compounding a compound that forms a complex with copper, for example, an oxime ester-based photopolymerization initiator is blended as a photopolymerization initiator in the photosensitive resin composition, and the thickness of the coating film is reduced. When the thickness is about 10 μm or less, it is possible to obtain a cured product that is more excellent in photosensitivity on the copper foil and has better adhesion to the copper foil. This is because at least the oxime ester photopolymerization initiator in the photosensitive resin composition is applied after the drying step of volatilizing volatile components such as a non-reactive diluent after coating the photosensitive resin composition on the copper foil. Based on the disappearance of some. That is, the disappearance of the oxime ester-based photopolymerization initiator on the copper foil appears particularly when a coating film of the photosensitive resin composition is formed to a thickness of about several μm to 10 μm from the copper foil surface, and the drying temperature. Also appears when the temperature is about 70 to 80 ° C. or higher. On the other hand, when the coating film of the photosensitive resin composition is formed to a thickness of about 20 μm or more from the copper foil surface, the disappearance degree of the oxime ester photopolymerization initiator is reduced. In addition, when the photosensitive resin composition is coated on a surface other than the copper foil surface, such as a polyimide base material or a glass epoxy resin base material, the disappearance of the oxime ester photopolymerization initiator described above is Does not occur. From this, the disappearance of the oxime ester-based photopolymerization initiator occurs because the thickness of the coating film of the photosensitive resin composition occurs in the range of several μm to 10 μm from the surface of the copper foil. It is thought to be due to the reaction. In addition, when the copper foil surface is oxidized, the disappearance phenomenon of the oxime ester photopolymerization initiator is not observed. This is considered because the reaction which copper intervened in the said drying process is suppressed by forming the oxide film more than fixed thickness on the copper foil surface. From the above, by blending a compound that forms a complex with copper, a film is formed on the copper foil, and the disappearance reaction of the oxime ester photopolymerization initiator described above is suppressed. Regardless of the type and regardless of the thickness of the coating film of the photosensitive resin composition, more excellent photosensitivity and adhesion can be obtained.

  The compound that forms a complex with copper is not particularly limited as long as it is a compound that can react with copper to form a complex, and examples thereof include a nitrogen-containing heterocyclic compound. The nitrogen-containing heterocyclic compound is not particularly limited, and examples thereof include a nitrogen-containing heterocyclic aromatic compound in which a benzene ring and a nitrogen-containing heterocyclic ring are bonded together on one side.

  The nitrogen-containing heterocyclic aromatic compound in which a benzene ring and a nitrogen-containing heterocyclic ring are bonded together on one side is not particularly limited. For example, on a copper foil, more excellent photosensitivity and adhesion can be reliably obtained. In terms of benzoxazole, benzoxazole skeleton compound (benzoxazole derivative), benzotriazole, benzotriazole skeleton compound (benzotriazole derivative), benzothiazole, benzothiazole skeleton compound (benzothiazole derivative), benzimidazole And a compound having a benzimidazole skeleton (benzimidazole derivative) and the like are preferable.

  The benzoxazole derivative is not particularly limited as long as it is a compound having a benzoxazole skeleton, and examples thereof include 2-mercaptobenzoxazole. The benzotriazole derivative is not particularly limited as long as it is a compound having a benzotriazole skeleton. For example, 1,2,3-benzotriazole, 1,2,3-benzotriazole sodium salt, carboxybenzotriazole, carboxybenzotriazole Phenyl ester, carboxybenzotriazole methyl ester, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5 Chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 1- [ N, N-bis (2-ethylhexyl) aminomethyl] benzotriazole, 2,2′- Methylenebis [6- (2H-benzotriazol-2-yl) -4-tert-octylphenol], 6- (2-benzotriazolyl) -4-tert-octyl-6′-tert-butyl-4′-methyl -2,2'-methylenebisphenol, 1- [N, N-bis (2-ethylhexyl) aminomethyl] methylbenzotriazole, 2,2 '-[[(methyl-1H-benzotriazol-1-yl) methyl] Imino] bisethanol and the like. The benzothiazole derivative is not particularly limited as long as it is a compound having a benzothiazole skeleton. For example, 2-mercaptobenzothiazole, 2- (methylthio) -2-benzothiazole, dodecanethioate S-benzothiazol-2-yl Ester, dibenzyldithiocarbamic acid benzothiazol-2-yl ester, 1- (1,2-benzisothiazol-3-yl) piperazine, N, N-bis (2-ethylhexyl) -2-benzothiazolylsulfenamide 2- (2-hydroxyphenyl) benzothiazole, benzothiazylthio-propionic acid, 3- (2-benzothiazylthio) propionic acid, 2-aminobenzothiazole and the like. The benzimidazole derivative is not particularly limited as long as it is a compound having a benzimidazole skeleton. For example, 2-mercaptobenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-carboxybenzimidazole, 1 , 3-dihydro-1-phenyl-2H-benzimidazole-2-thione, 2-mercapto-5-nitrobenzimidazole, 2-mercapto-5-aminobenzimidazole and the like. These compounds may be used alone or in combination of two or more.

  Of these, benzoxazole and benzoxazole derivatives are preferred from the viewpoint of alkali developability.

  Although content of the compound which forms a complex with copper is not specifically limited, For example, even if the thickness of a coating film is about 10 micrometers or less with respect to 100 mass parts of carboxyl group-containing photosensitive resin, on the copper foil Is preferably 0.10 parts by mass from the viewpoint of reliably obtaining the photosensitivity and adhesion to the copper foil, more preferably 0.20 parts by mass from the viewpoint of more reliably suppressing disappearance of the oxime ester photopolymerization initiator, .30 parts by mass is particularly preferred. On the other hand, the upper limit is preferably 5.0 parts by mass with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin from the viewpoint of alkali developability and the insulation reliability of the cured product, and oxidation of the copper foil in the post cure. 3.0 mass parts is more preferable from the point of prevention, and 2.0 mass parts is especially preferable.

  The colorant is not particularly limited, such as a pigment or a dye, and any color such as a white colorant, a blue colorant, a green colorant, a yellow colorant, a purple colorant, and a black colorant can be used. Examples of the colorant include inorganic colorants such as titanium oxide which is a white colorant, carbon black which is a black colorant, phthalocyanine green which is a green colorant, and phthalocyanine blue and lionol blue which are blue colorants. And organic colorants such as phthalocyanine and anthraquinone.

  Examples of the flame retardant include a phosphorus-based flame retardant. Examples of phosphorus-based flame retardants include tris (chloroethyl) phosphate, tris (2,3-dichloropropyl) phosphate, tris (2-chloropropyl) phosphate, tris (2,3-bromopropyl) phosphate, and tris (bromo). Halogenated phosphoric acid such as chloropropyl) phosphate, 2,3-dibromopropyl-2,3-chloropropyl phosphate, tris (tribromophenyl) phosphate, tris (dibromophenyl) phosphate, tris (tribromoneopentyl) phosphate Esters; non-halogen aliphatic phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxyethyl phosphate; triphenyl phosphate; Residyl diphenyl phosphate, dicresyl phenyl phosphate, tricresyl phosphate, trixylenyl phosphate, xylenyl diphenyl phosphate, tris (isopropylphenyl) phosphate, isopropylphenyl diphenyl phosphate, diisopropylphenylphenyl phosphate, tris (trimethylphenyl) phosphate, Non-halogen aromatic phosphates such as tris (t-butylphenyl) phosphate, hydroxyphenyl diphenyl phosphate, octyl diphenyl phosphate; aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, bisdiethylphosphinic acid Zinc, bismethylethylphosphinic acid Lead, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, titanium tetrakisdiphenylphosphinate, etc. Metal salt, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (hereinafter referred to as HCA), addition reaction product of HCA and acrylate ester, addition reaction product of HCA and epoxy resin, HCA HCA modified compounds such as hydroquinone addition products, diphenylvinylphosphine oxide, triphenylphosphine oxide, trialkylphosphine oxide, tris (hydroxyalkyl) phosphine oxy Phosphine oxide compounds such as id and the like. Of these, organophosphate flame retardants are preferred.

Various additives Various additives include antifoaming agents such as silicone, hydrocarbon and acrylic, dicyandiamide (DICY) and its derivatives, melamine and its derivatives, boron trifluoride-amine complex, organic acid hydrazide, diamino Curing catalysts such as maleonitrile (DAMN) and its derivatives, guanamine and its derivatives, amine imide (AI) and polyamine, extender pigments such as talc, barium sulfate, alumina, aluminum hydroxide, mica and silica, organics such as powder urethane resin A filler etc. can be mentioned.

Non-reactive diluent The non-reactive diluent is for adjusting the viscosity and drying property of the photosensitive resin composition. Examples of non-reactive diluents include organic solvents. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexane, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, Petroleum solvents such as petroleum ether and petroleum naphtha, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, ethyl acetate, butyl acetate, cellosolve acetate, butylcellosolve acetate, carbitol acetate and butyl carbitol Examples thereof include esters such as acetate, diethylene glycol monomethyl ether acetate, and ethyl diglycol acetate. The blending ratio of the non-reactive diluent in the photosensitive resin composition is not particularly limited. For example, 5.0 to 100 parts by mass is preferable with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, and 10 to 50 is preferable. Part by mass is particularly preferred.

  The method for producing the photosensitive resin composition of the present invention is not limited to a specific method. For example, after blending each of the above components at a predetermined ratio, at room temperature, a kneading means such as a three roll, ball mill, sand mill, or the like, or It can be produced by kneading or mixing with a stirring means such as a super mixer or a planetary mixer. Further, prior to the kneading or mixing, if necessary, preliminary kneading or premixing may be performed.

  Next, the usage method of the above-mentioned photosensitive resin composition of this invention is demonstrated. Here, the case where the photosensitive resin composition of the present invention is applied as a solder resist film on a substrate on which a copper foil conductor circuit pattern is formed will be described as an example.

  The photosensitive resin composition of the present invention obtained as described above, for example, on a flexible printed wiring board having a circuit pattern formed by etching a copper foil, screen printing, spray coater, bar coater, applicator, The coating is applied to a desired thickness using a known coating method such as a blade coater, knife coater, roll coater or gravure coater. After coating, when the photosensitive resin composition of the present invention contains an organic solvent, preliminary drying is performed by heating at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes in order to volatilize the organic solvent. To form a tack-free coating. Next, a negative film (photomask) having a pattern in which a part other than the land of the circuit pattern is made to be translucent is adhered onto the coated photosensitive resin composition, and ultraviolet rays (for example, in a wavelength range of 300 to 400 nm) are formed thereon. ). Then, the coating film is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. As the developing method, a spray method, a shower method, or the like is used, and examples of the diluted alkaline aqueous solution used include 0.5 to 5% by mass of an aqueous sodium carbonate solution. Next, a target solder resist film can be formed on a circuit board such as a flexible printed wiring board by performing post-cure for 20 to 80 minutes with a hot-air circulating dryer at 130 to 170 ° C.

  Next, examples of the present invention will be described. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Examples 1-5, Comparative Examples 1-6
Ingredients shown in Tables 1 and 2 below are blended at the blending ratios shown in Tables 1 and 2 below, mixed and dispersed at room temperature using three rolls, and in Examples 1 to 5 and Comparative Examples 1 to 6 A photosensitive resin composition to be used was prepared. Unless otherwise indicated, the compounding quantity of each component shown to the following Tables 1 and 2 shows a mass part. In addition, the blank part of the compounding quantity in the following Tables 1 and 2 means no compounding.

Details of each component in Tables 1 and 2 are as follows.
(A) Carboxyl group-containing photosensitive resin / SP-4621: solid content (resin content) 65 mass%, Showa Polymer Co., Ltd.
-ZAR-2000, ZCR-1569H, FLX-2089: all solid content (resin content) 65 mass%, Nippon Kayaku Co., Ltd.
SP-4621, ZAR-2000 and ZCR-1569H are obtained by reacting at least part of the epoxy group of the epoxy resin with acrylic acid to obtain an epoxy acrylate, and reacting the generated hydroxyl group with a polybasic acid. This is a polybasic acid-modified epoxy acrylate having no urethane bond.
FLX-2089 is a structure obtained by reacting a compound having a hydroxyl group and a carboxyl group and a polyisocyanate compound with epoxy methacrylate obtained by reacting methacrylic acid with at least a part of the epoxy group of the epoxy resin. It is an acid-modified urethane-modified epoxy methacrylate.

(B) Reactive diluent: DPCA-120: ε-caprolactone modified dipentaerythritol hexaacrylate, caprolactone has an average number of repeating units of 2, Nippon Kayaku Co., Ltd.
DPCA-60: ε-caprolactone-modified dipentaerythritol hexaacrylate, caprolactone has an average number of repeating units of 1, Nippon Kayaku Co., Ltd.
・ DPHA: Nippon Kayaku Co., Ltd.
・ KRM-8296, EBERCRYL8405: Daicel Ornex

(C) Photopolymerization initiator, NCI-831: ADEKA, Irgacure 369: BASF

(D) Epoxy compound / NC-3000: Nippon Kayaku Co., Ltd.
・ YX-4000HK: Mitsubishi Chemical Corporation

Compound that forms a complex with copper 2MBO: Aldrich Chemical Co., Ltd. Curing catalyst DICY-7: Mitsubishi Chemical Corporation
・ Melamine: Nissan Chemical Industries, Ltd.
Colorant Lionol Blue FG-7351: Toyo Ink Manufacturing Co., Ltd.
・ Denka Black: Electrochemical Industry Co., Ltd.
Organic filler RHC-730: Dainichi Seika Kogyo Co., Ltd.
Extender pigment, ACE MATT OK412: Evonik Japan
Non-reactive diluent / EDGAC: Sanyo Chemicals Co., Ltd.
Antifoaming agent, KS-66: Shin-Etsu Chemical Co., Ltd.
Flame Retardant Exolit OP-935: Clariant Japan Co., Ltd.

Test piece preparation process Substrate: Polyimide film (Nippon Steel & Sumikin Chemical Co., Ltd. “ESPANEX”, copper foil thickness 12 μm, polyimide film thickness 25 μm)
Surface treatment: 5% by mass sulfuric acid treatment Coating method: screen printing DRY film thickness: 20 μm
Pre-drying: 80 ° C., 20 minutes Exposure: 100 mJ / cm ² , exposure with Oak UV DI UV exposure device “Mns60” (light source is high-pressure mercury lamp) Development: 1 mass% sodium carbonate aqueous solution Temperature 30 ° C., spray pressure 0 .2 MPa, development time 60 seconds Post cure: 150 ° C., 60 minutes

The evaluation items are as follows.
(1) Sensitivity Stepped tablet for sensitivity measurement (14 stages of Kodak) is installed on the pre-dried coated substrate in the above test piece preparation process, and the amount of ultraviolet light with a main peak of 365 nm is passed through the step tablet. the O - click Corporation test pieces those irradiated 100 mJ / cm ² using the integrated light intensity meter - a scan, using a 1 mass% sodium carbonate aqueous solution, carried out at a spray pressure of 0.2 MPa, 60 seconds, the development The portion of the exposed portion after removal that is not removed is represented by a number (number of steps). The larger the number of steps, the better the photosensitive characteristics.

(2) Warpage property After cutting out the test piece prepared in the above-mentioned test piece preparation step to 3 cm × 3 cm, place the cut out test piece gently on a horizontal table so that the top is concave, and apply external force. The vertical distance between the four corners of the test piece and the table was measured with a straight scale, and the maximum value was adopted. Evaluation was performed in the following four stages.
◎: Less than 1 mm ○: 1 mm or more to less than 3 mm △: 3 mm or more to less than 5 mm x: 5 mm or more

(3) Flexibility (flexibility)
About the test piece produced in the above-mentioned test piece production step, 180 ° folding is repeated several times by goblet folding, and the crack occurrence state in the cured coating film at that time is observed visually and with an optical microscope of x200, and the occurrence of the crack The number of times that did not occur was measured. The measurement results were evaluated in the following four stages.
◎: 5 times or more ○: 4 times to 2 times △: 1 time ×: 1 time cracking

(4) Solder heat resistance About the test piece produced in the above-mentioned test piece production process, Tamura Seisakusho Co., Ltd. flux: ULF-210R was applied, floated in a solder bath at 260 ° C. for 10 seconds, and then peeled off with a cellophane tape. (Peel test) was repeated, and the state of the coating film was observed visually and with an optical microscope of x200 to evaluate whether the coating film was swollen or peeled off. The measurement results were evaluated as follows.
◎: No swelling or peeling of coating film even after 5 peeling tests ○: No swelling or peeling of coating film from 4 to 2 peeling tests △: Occurrence of swelling and peeling of coating film until 1 peeling test None x: Swelling or peeling of the coating occurs in one peeling test

(5) High temperature solder dip characteristics About the test piece produced in the above-mentioned test piece production process, it was repeatedly immersed in a 350 ° C. solder bath for 10 seconds, and the coating state was observed visually and with an optical microscope of x200, It was evaluated whether the coating film was swollen or peeled off. The measurement results were evaluated as follows.
A: No swelling or peeling of the coating film even after 5 immersions O: No swelling or peeling of the coating film from 4 to 2 immersions Δ: No swelling or peeling of the coating film until 1 immersion ×: Swelling and peeling of the coating occurs after one immersion

  The evaluation results of the examples are shown in Table 1, and the evaluation results of the comparative examples are shown in Table 2.

  From Table 1 above, Example 1 in which caprolactone-modified acrylate (caprolactone-modified dipentaerythritol hexaacrylate) was used as a reactive diluent and a carboxyl group-containing photosensitive resin having no urethane bond was used as a carboxyl group-containing photosensitive resin. In -5, the cured coating film which was excellent in the low curvature property and the softness | flexibility, and was excellent also in the solder heat resistance and the high temperature solder dip characteristic, without impairing a sensitivity was able to be obtained. In particular, from Examples 1 and 2, the caprolactone-modified acrylate having an average number of repeating units of caprolactone of 2 is lower in warpage and flexibility than the caprolactone-modified acrylate having an average number of repeating units of caprolactone of 1. Thus, an excellent cured coating film could be obtained. Also, from Examples 1 and 3, it is better to use the caprolactone-modified acrylate alone as a reactive diluent and the other acrylate compound, and to use the caprolactone-modified acrylate alone for better curling and flexibility. A coating film could be obtained.

  On the other hand, from Table 2 above, from Comparative Examples 1 and 2, when 20 to 50% by mass of a carboxyl group-containing photosensitive resin having a urethane bond is contained in the carboxyl group-containing photosensitive resin, high-temperature solder dip characteristics are obtained. Therefore, solder heat resistance at a high temperature of 350 ° C. or higher was not obtained. Further, in Comparative Example 3 in which caprolactone-modified acrylate was not blended as a reactive diluent, low warpage and flexibility were not obtained. Moreover, in Comparative Examples 4-6 which mix | blended urethane acrylate as a reactive diluent, the high temperature solder dip characteristic was not acquired.

  In the photosensitive resin composition of the present invention, a cured product excellent in flexibility and heat resistance, particularly solder heat resistance at a high temperature of 350 ° C. or higher can be obtained. For example, it is useful in the field of flexible printed wiring boards. Is expensive.

Claims (7)

(A) A photosensitive resin composition containing a carboxyl group-containing photosensitive resin, (B) a reactive diluent, (C) a photopolymerization initiator, and (D) an epoxy compound,
(A) The carboxyl group-containing photosensitive resin having a urethane bond contained in the carboxyl group-containing photosensitive resin is 10% by mass or less, and the (B) reactive diluent contains a caprolactone-modified (meth) acrylate. And a photosensitive resin composition characterized by being a compound having no urethane bond.   The photosensitive resin composition according to claim 1, wherein the (A) carboxyl group-containing photosensitive resin is a resin having no urethane bond.   The photosensitive resin composition according to claim 1 or 2, wherein the caprolactone-modified (meth) acrylate has an average number of repeating units of caprolactone of 2 or more.   The photosensitive resin composition according to any one of claims 1 to 3, wherein the caprolactone-modified (meth) acrylate is a caprolactone-modified (meth) acrylate having 5 or more functionalities.   5. The caprolactone-modified (meth) acrylate is contained in an amount of 20 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. The photosensitive resin composition as described.   The photocured material of the photosensitive resin composition of any one of Claims 1 thru | or 5.   The printed wiring board which has a photocuring film of the photosensitive resin composition of any one of Claims 1 thru | or 5.