JP2007147722A - Photosensitive thermosetting resin composition and insulation protective coating formed by curing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive thermosetting resin composition excellent in bleed-out resistance and developability, and having such high flame retardancy as to pass a UL combustion test. <P>SOLUTION: The photosensitive thermosetting resin composition contains (A) a carboxy modified epoxy (meth)acrylate resin, (B) 6-H-dibenz[c,e][1,2]oxaphosphorin-6-[2,5-bis(oxiranylmethoxy)phenyl]-6-oxide, (C) a photopolymerization initiator, (D) a diluent, (E) a curing agent, (F) melamine polyphosphate, and (G) aluminum hydroxide, wherein the component (B) is contained in such an amount that a phosphorus content deriving from the component (B) in a resin composition comprising the components (A)-(E) becomes 1-2 mass%, the component (F) is contained in such an amount that a phosphorus content deriving from the component (F) becomes 1.5-2.5 mass% based on 100 parts by mass of the resin composition, and the component (G) is contained in an amount of 30-50 parts by mass based on 100 parts by mass of the resin composition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used as an interlayer insulating resin for printed wiring boards or a solder resist that can be developed with an alkaline aqueous solution, and is excellent in bleed-out resistance and developability, and has high flame resistance that passes the UL combustion test. The present invention relates to a photosensitive thermosetting resin composition having a property and an insulating protective film formed by curing the composition.

  In the production of a printed wiring board, various substrate protection means such as a resist used in etching and a solder resist used in a soldering process are conventionally required. Even in the process of manufacturing a film-like printed wiring board (FPC) used for small devices, a solder resist for protecting irrelevant wiring is required in a soldering process for mounting components.

  Conventionally, as such a substrate protection means, a cover lay using a polyimide film punched into a predetermined mold or a cover coat for printing an ink made of a heat resistant material has been used. These coverlays and covercoats also serve as a wiring protective film after soldering, and are required to have heat resistance and insulation during soldering, and flexibility that does not cause cracks when bent during board incorporation. Furthermore, the flame retardancy defined in UL standards is also required.

Coverlays formed by punching polyimide film satisfy the above-mentioned requirements and are currently most frequently used. However, expensive molds are required for punching, and punched film pieces are manually handled. Therefore, there is a problem that it is expensive to align and bond to the substrate, and it is difficult to form a fine pattern.
Since the cover coat requires a drying process for screen printing, there is a problem that the manufacturing cost is high and workability is poor.

  As a method for solving these problems, there has been proposed a method in which a photosensitive resin composition is applied in a liquid form on a substrate or attached in a film form. According to this method, a fine pattern cover coat or cover lay can be easily formed by forming a film on a substrate and then exposing, developing, and heating by photographic technology. Therefore, various photosensitive resin compositions have been developed conventionally.

As a method for imparting flame retardancy to a photosensitive resin composition, a conventional flame retardant such as a brominated epoxy resin, a flame retardant system obtained by combining a flame retardant aid such as antimony trioxide with this, etc. (For example, see Patent Documents 1 and 2). However, along with the rise of global environmental problems, importance of further low toxicity, low pollution, and safety has become important. Not only is it difficult to burn, but there is no generation of toxic gas and low smoke emission. It is requested. Organophosphorus compounds are known as flame retardants that do not contain halogens and that provide a relatively good flame retardant effect (see, for example, Patent Documents 3, 4, and 5). However, only the phosphoric acid ester, which is a conventional organic phosphorus flame retardant, has a weak flame-retardant effect and is uneasy about heat resistance and bleed-out resistance. Moreover, in addition to the halogen-free flame retardancy, it is also necessary to cope with the use of lead-free solder in printed wiring boards. In the case of lead-free solder, the general flow and reflow temperature of the conventional Pb / Sn eutectic solder is 10 to 20 ° C higher than the conventional reflow temperature of about 260 ° C. Yes.
JP-A-9-325490 JP-A-11-242331 JP 9-235449 A Japanese Patent Laid-Open No. 10-306201 JP 11-271967 A

  In general, epoxy-based solder resists are generally used as photosensitive solder resists. In order to make the epoxy-based resist flame retardant, in consideration of the environment, a phosphoric ester that is an organic phosphorus flame retardant containing no halogen or a metal hydrate that is an inorganic flame retardant may be used. However, phosphate esters have a problem of reducing bleed-out resistance. Further, since metal hydrate is flame retardant, when it is added in a large amount, there is a problem of lowering the folding resistance and developability of the film.

  The present invention has been made in view of the above circumstances, and is a photosensitive thermosetting resin composition having excellent bleed-out resistance and developability, and having high flame resistance that passes the UL combustion test, and curing the same. It is an object of the present invention to provide an insulating protective film.

In order to solve the above problems, the present invention provides (A) a carboxy-modified epoxy (meth) acrylate resin and (B) 6-H-dibenzo [c, e] [1,2] oxaphosphorin-6- [2 , 5-bis (oxiranylmethoxy) phenyl] -6-oxide, (C) a photopolymerization initiator, (D) a diluent, (E) a curing agent, (F) melamine polyphosphate, G) Aluminum hydroxide is contained, and the phosphorus content derived from the component (B) in the resin component consisting of the components (A) to (E) is 1.0 to 2.0. The component (F) is contained in an amount of mass%, and the phosphorus content derived from the component (F) is 1.5 to 100 parts by mass of the resin composition consisting of the components (A) to (E). It is contained so that it may become 2.5 mass%, The said (G) component consists of said (A)-(E) component. To provide a photosensitive thermosetting resin composition characterized that contains 30 to 50 parts by weight with respect to fat composition per 100 parts by weight.
Moreover, this invention provides the insulating protective film formed by hardening | curing the above-mentioned photosensitive thermosetting resin composition.

  According to the present invention, a photosensitive thermosetting resin composition that provides an insulating protective film having high flame retardancy that passes the UL standard combustion test and excellent in bleed-out resistance and developability by the above-described formulation. You can get things.

Hereinafter, the present invention will be described in detail based on the best mode.
The photosensitive thermosetting resin composition of the present invention comprises (A) a carboxy-modified epoxy (meth) acrylate resin and (B) 6-H-dibenzo [c, e] [1,2] oxaphospholine-6- [2,5-bis (oxiranylmethoxy) phenyl] -6-oxide, (C) a photopolymerization initiator, (D) a diluent, (E) a curing agent, (F) melamine polyphosphate, (G) Aluminum hydroxide is contained, The said (B) component has phosphorus content derived from the (B) component in the resin composition which consists of said (A)-(E) component 1-2 mass%. The component (F) has a phosphorus content derived from the component (F) of 1.5 to 100 parts by mass of the resin component consisting of the components (A) to (E). It is contained so that it may become 2.5 mass%, and the said (G) component is said (A)-(E) component? Characterized in that it contains 30 to 50 parts by weight with respect to become the resin composition per 100 parts by weight.
In the present invention, “(meth) acrylate” refers to acrylate, methacrylate, or a mixture thereof. Similarly, “(meth) acrylic acid” refers to acrylic acid, methacrylic acid or mixtures thereof.

  Carboxy-modified epoxy (meth) acrylate resin (this may be referred to as “component (A)”), which is an essential component of the photosensitive thermosetting resin composition of the present invention, is an epoxy resin, (meth) acrylic acid, This is a resin obtained by reacting polyvalent carboxylic acid anhydride after the reaction.

Examples of the epoxy resin used as a raw material include those whose main skeleton is a bisphenol type epoxy resin such as a bisphenol F type epoxy resin or a bisphenol A type epoxy resin, and specific examples include KAYARAD (registered trademark) ZFR. Commercial products such as ZAR (manufactured by Nippon Kayaku Co., Ltd.) can be used.
Similarly, (meth) acrylic acid used as a raw material includes acrylic acid, methacrylic acid, and mixtures thereof.

  Furthermore, as the polyvalent carboxylic anhydride used as a raw material, phthalic anhydride, succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, Examples thereof include anhydrides of divalent carboxylic acids such as itaconic anhydride and methylendomethylenetetrahydrophthalic anhydride.

  6-H-dibenzo [c, e] [1,2] oxaphosphorine-6- [2,5-bis (oxiranylmethoxy) phenyl, which is an essential component of the photosensitive thermosetting resin composition of the present invention ] -6-oxide (in English, 6-H-dibenz [c, e] [1,2] oxaphosphorin-6- [2,5-bis (oxylenyloxy) phenyl] -6-oxide, also abbreviated as DOPO. In the invention, this may be referred to as “component (B)”) is a thermosetting phosphorus atom-containing epoxy monomer represented by the formula (1).

  For example, DOPO is synthesized from 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA-HQ) represented by formula (2) as a raw material. And glycidylation of a hydroxyl group (condensation reaction with epichlorohydrin (ECH)).

  The photopolymerization initiator (which may be referred to as “component (C)”), which is an essential component of the photosensitive thermosetting resin composition of the present invention, is a reaction of the (meth) acryloyl group of the component (A). It is a compound that induces radical polymerization by inducing. Examples of the photopolymerization initiator (C) used in the present invention include benzoins such as benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and benzoin isobutyl ether; benzophenone, methyl benzophenone, 4 -Benzophenones such as phenylbenzophenone, hydroxybenzophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis (diethylamino) benzophenone, Michler's ketone, benzoylbenzoic acid, 4-benzoyl-4'-methyldiphenyl sulfide 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, p-dimethylaminopropion Non, 1,1-dichloroacetophenone, 4-phenoxydichloroacetophenone, trichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [ Acetophenones such as 4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, N, N-dimethylaminoacetophenone Thioxanthones such as thioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; 2-methylanthraquino , 2-ethylanthraquinone, 2-tert-butyl anthraquinone, 1-chloro anthraquinone, 2-amyl anthraquinone, 2-aminoanthraquinone, and the like anthraquinones such as 2,3-diphenyl anthraquinone. These photopolymerization initiators can be used alone or in combination of two or more.

  Furthermore, a photosensitizer can be used in combination with the photopolymerization initiator as necessary. Examples of the photosensitizer include tertiary amines such as dimethylaminobenzoic acid ethyl ester, dimethylaminobenzoic acid isoamyl ester, dimethylaminobenzoic acid pentyl ester, triethylamine, and triethanolamine. These photosensitizers can be used alone or in combination of two or more.

  As a preferable combination of the photopolymerization initiator (C), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one (manufactured by Ciba Specialty Chemicals, trade name: IRUGACURE 907) ) And 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYACURE DETX).

  The diluent (this may be referred to as “component (D)”), which is an essential component of the photosensitive thermosetting resin composition of the present invention, is an unsaturated compound such as a (meth) acrylate monomer or an organic solvent. Can be mentioned.

  Examples of (meth) acrylate monomers include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; glycols such as ethylene glycol, methoxytetraethylene glycol and polyethylene glycol Mono- or di (meth) acrylates; aminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, tris Polyhydric alcohols such as hydroxyethyl isocyanurate or polyvalent (meth) acrylates of these ethylene oxide or propylene oxide adducts; (Meth) acrylates of ethylene oxide or propylene oxide adducts of phenols such as ethyl (meth) acrylate and bisphenol A polyethoxydi (meth) acrylate; glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, triglycidyl isocyanurate, etc. (Meth) acrylates of glycidyl ether; ε-caprolactone-modified (meth) acrylates such as caprolactone-modified tris ((meth) acryloxyethyl) isocyanurate; melamine (meth) acrylate, etc., which may be used alone or in combination The above can be used in combination.

  Specific examples of organic solvents include ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, diethylene glycol monoalkyl ether acetates, petroleum naphtha, etc. These may be used alone or in combination of two or more.

  As a curing agent that is an essential component of the photosensitive thermosetting resin composition of the present invention (sometimes referred to as “component (E)”), a curing agent (heat) that is usually used to accelerate curing of an epoxy resin is used. The polymerization catalyst is not particularly limited. Specific examples of the epoxy resin curing agent that can be used as the curing agent (E) include 2MZ, 2E4MZ, C11Z, C17Z, 2PZ, 1B2MZ, 2MZ-CN, 2E4MZ-CN, C11Z-CN, 2PZ-CN, Imidazoles such as 2PHZ-CN, 2MZ-CNS, 2E4MZ-CNS, 2PZ-CNS, 2MZ-AZINE, 2E4MZ-AZINE, C11Z-AZINE, 2MA-OK, 2P4MHZ, 2PHZ, 2P4BHZ (manufactured by Shikoku Chemical Industries, Ltd.) Derivatives; guanamines such as acetoguanamine and benzoguanamine; polyamino such as diaminodiphenylmethane, m-phenylenediamine, m-xylenediamine, diaminodiphenylsulfone, dicyandiamide, urea, urea derivative, melamine, polybasic hydrazide Organic acid salts and / or epoxy adducts of the above polyamines; amine complexes of boron trifluoride; ethyldiamino-S-triazine, 2,4-diamino-S-triazine, 2,4-diamino-6-xylyl- Triazine derivatives such as S-triazine; trimethylamine, triethanolamine, N, N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmorpholine, hexa (N-methyl) melamine, 2,4,6- Tertiary amines such as tris (dimethylaminophenol), tetramethylguanidine, m-aminophenol; polyphenols such as polyvinylphenol, polyvinylphenol bromide, phenol novolac, alkylphenol novolac; benzyltrimethylammonium chloride, phenol Quaternary ammonium salts such as rutributylammonium chloride; polybasic acid anhydrides; diphenyliodonium tetrafluoroborate; triphenylsulfonium hexafluoroantimonate, Irgacure-261 (manufactured by Ciba Geigy), Optoma-SP-170 (Asahi Denka) Photo-cationic polymerization catalyst such as styrene-maleic anhydride resin; equimolar reaction product of phenyl isocyanate and dimethylamine, equimolar reaction product of organic polyisocyanate such as tolylene diisocyanate and isophorone diisocyanate and dimethylamine, etc. These known and commonly used curing agents and curing accelerators can be used alone or in admixture of two or more.

Melamine polyphosphate (which may be referred to as “component (F)”), which is an essential component of the photosensitive thermosetting resin composition of the present invention, is a compound known as a salt of melamine and polyphosphate.
Furthermore, the photosensitive thermosetting resin composition of the present invention contains aluminum hydroxide (this may be referred to as “(G) component”) as an essential component.

And in the photosensitive thermosetting resin composition of this invention, the quantity of (B) component, (F) component, and (G) component adjusts the addition amount with the required flame retardance.
Specifically, the content of the component (B) (DOPO) is such that the phosphorus content derived from the component (B) in the resin composition comprising the components (A) to (E) is 1.0 to 2. 0.0 mass%. When the phosphorus content derived from the component (B) is less than 1.0% by mass, adhesion and folding resistance as the solder resist (SR) cannot be obtained, and the phosphorus content derived from the component (B). If it exceeds 2.0% by mass, the developability is lowered.

  Furthermore, the content of the component (F) (melamine polyphosphate) is such that the phosphorus content derived from the component (F) is 1. with respect to 100 parts by mass of the resin composition composed of the components (A) to (E). It is made to become 5-2.5 mass%. When the phosphorus content derived from the component (F) is less than 1.5% by mass, a flame retardant effect equivalent to V-0 in the UL test cannot be obtained, and the phosphorus content derived from the component (F) is 2. When it exceeds 5% by mass, the folding resistance of the film is lowered.

  Furthermore, content of the said (G) component (aluminum hydroxide) shall be 30-50 mass parts with respect to 100 mass parts of resin components which consist of said (A)-(E) component. When the content of component (G) is less than 30 parts by mass, a flame retardant effect equivalent to V-0 in the UL test cannot be obtained, and when the content of component (G) exceeds 50 parts by mass, Decrease foldability and developability.

  Furthermore, the photosensitive thermosetting resin composition of the present invention is colored as an optional component in addition to the base resin composition consisting of the components (A) to (E), the component (F) and the component (G). A surfactant, a surfactant as a flow regulator, a polymerization inhibitor, a thickener, an antifoaming agent, a leveling agent, an adhesion imparting agent, and the like can be appropriately added within a range not impairing the effects of the present invention. .

  Examples of the thermal polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, tert-butylcatechol, pyrogallol, phenothiazine and the like. Examples of the thickener include asbestos, olben, benton, montmorillonite and the like. The antifoaming agent is used for eliminating bubbles generated at the time of printing, coating, and curing, and specific examples include acrylic and silicon surfactants. The leveling agent is used to lose the unevenness on the surface of the film generated during printing and coating, and specifically includes an acrylic or silicon surfactant. Examples of the adhesion imparting agent include imidazole, thiazole, triazole, and silane coupling agents.

  The photosensitive thermosetting resin composition of this invention can be manufactured by mixing said each component by a normal method. The mixing method is not particularly limited, and a part of the components may be mixed and then the remaining components may be mixed, or all the components may be mixed at once. Specifically, it is preferable to melt and knead after mixing each of the above-described components. For example, melt kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder, and a kneader. It is manufactured by doing. The melting temperature is preferably in the range of 60 to 130 ° C.

  The photosensitive thermosetting resin composition of the present invention is coated on a substrate or base material with an appropriate thickness, heat-treated and dried, and then exposed, developed, and thermally cured to cure. It can be a protective film. The photosensitive thermosetting resin composition of the present invention can be used for various applications.

  In the case of forming an insulating protective film, a photosensitive thermosetting resin composition is applied in a thickness of 10 μm to 50 μm on a substrate on which a circuit is formed by a conductor, and then 5 in a temperature range of 60 ° C. to 100 ° C. After heat treatment for about 30 minutes and drying to a thickness of 5 to 40 μm, exposure is performed through a negative mask having a desired exposure pattern, and the unexposed portion is removed with a developing solution and developed. A method of curing by thermosetting for about 10 to 40 minutes in a temperature range of ˜180 ° C. is exemplified. Since the photosensitive thermosetting resin composition of the present invention is excellent not only in flame retardancy but also in folding resistance and developability, it is particularly suitable for use as an insulating protective film on an FPC board. Further, for example, it may be used as an insulating resin layer between layers of a multilayer printed wiring board.

  As the active light used for exposure, active light generated from a known active light source such as a carbon arc, a mercury vapor arc, a xenon arc, or the like is used. Since the sensitivity of the photopolymerization initiator (C) contained in the photosensitive layer is usually maximum in the ultraviolet region, the active light source preferably emits ultraviolet rays effectively. Of course, when the photopolymerization initiator (C) is sensitive to visible light, such as 9,10-phenanthrenequinone, visible light is used as the active light, and the active light source is the active light. In addition to the light source, a flood bulb for photography, a solar lamp, etc. are also used.

  As the developer, an alkaline aqueous solution such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines and the like can be used.

  The photosensitive thermosetting resin composition of this invention can also be used for the photosensitive layer of a photosensitive dry film. The photosensitive dry film has a photosensitive layer made of a photosensitive thermosetting resin composition on a support made of a polymer film or the like. The thickness of the photosensitive layer is preferably 10 to 70 μm. Examples of the polymer film used for the support include polyethylene terephthalate, polyester resins such as aliphatic polyester, and films made of polyolefin resins such as polypropylene and low density polyethylene. Among these, polyester and low density A film made of polyethylene is preferred. Moreover, since it is necessary to remove these polymer films from the photosensitive layer later, it is preferable that these polymer films can be easily removed from the photosensitive layer. The thickness of these polymer films is usually 5 to 100 μm, preferably 10 to 30 μm.

  The photosensitive dry film can be produced by a photosensitive layer forming step in which a photosensitive thermosetting resin composition is applied on a support and dried. Further, by providing a cover film on the formed photosensitive layer, a support, a photosensitive layer, and a cover film are sequentially laminated, and a photosensitive dry film having films on both sides of the photosensitive layer can also be produced. The cover film is peeled off when the photosensitive dry film is used, but by providing the cover film on the photosensitive layer until the time of use, the photosensitive layer can be protected, and the photosensitive dry film has an excellent pot life. As the cover film, the same polymer film used for the above-mentioned support can be used, and the cover film and the support may be the same material or different materials, and the thickness is also the same. They may be the same or different.

  In order to form an insulating protective film on a printed wiring board using a photosensitive dry film, first, a bonding step of bonding the photosensitive layer of the photosensitive dry film and the substrate is performed. Here, when using a photosensitive dry film provided with a cover film, the cover film is peeled off to expose the photosensitive layer, and then contacted with the substrate. And a photosensitive layer and a board | substrate are thermocompression-bonded at about 40-120 degreeC with a pressure roller etc., and a photosensitive layer is laminated | stacked on a board | substrate.

  Then, an exposure step of exposing the photosensitive layer through a negative mask having a desired exposure pattern, a step of peeling the support from the photosensitive layer, a development step of removing the unexposed portion with a developer and developing, By performing the thermosetting process which thermosets a layer, the printed wiring board by which the insulating protective film was provided in the surface of the board | substrate can be manufactured. Moreover, you may form an insulating resin layer between the layers of a multilayer printed wiring board using such a photosensitive dry film. In addition, what was mentioned above can be used similarly for the active light and developing solution which are used for exposure.

  When the photosensitive thermosetting resin composition of the present invention is used, it has a beautiful appearance and has excellent bleed-out resistance and high folding resistance capable of withstanding 180 ° folding despite having excellent flame retardancy including a flame retardant. Therefore, it is possible to form an insulating hardened film that is excellent in photosensitivity and developability, and further satisfies performances such as heat resistance, electrical insulation, and adhesion to a wiring board. The insulating cured film of the present invention is particularly excellent in bleed-out resistance, folding resistance, flame resistance, flexibility, electrical insulation and appearance. Therefore, when used in a printed wiring board, it is not contaminated by surface bleed, can withstand 180 ° bending, does not curl, and has excellent electrical performance and handling properties. It is suitable as a protective film.

(Materials used)
As the component (A), bisphenol F type epoxy acrylate KARAYAD ZFR-1122 (trade name, manufactured by Nippon Kayaku Co., Ltd.) was used.
As the component (B), one synthesized according to the following DOPO synthesis method was used.
As the component (C), IRUGACURE 907 (trade name, manufactured by Ciba Specialty Chemicals) and KAYACURE DETX-S (trade name, manufactured by Nippon Kayaku Co., Ltd.) were used in combination.
As the component (D), acrylate monomer KARAYAD DPCA120 (trade name, manufactured by Nippon Kayaku Co., Ltd.) was used.
As the component (E), C11Z-CN (trade name, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was used.
As the component (F), PMP-200 (trade name, manufactured by Nissan Chemical Industries, Ltd.) was used.
As the component (G), Heidilite H-42S (trade name, manufactured by Showa Kosan Co., Ltd.) was used.

  The condensed phosphate ester (hereinafter referred to as the (X) component) used in Comparative Example 1 is CR-741 (trade name, manufactured by Daihachi Chemical Industry Co., Ltd.).

(DOPO synthesis method)
To a four-necked glass separable flask equipped with a stirrer, a thermometer, and a condenser tube, 10- (2,5-dihydroxyphenyl) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide 64.9 parts of (HCA-HQ), 200 parts of epichlorohydrin (ECH), and 10 parts of tetrabutylammonium chloride were charged and stirred. After 4 hours of stirring, the temperature of the reaction system was raised to 85 ° C., and 32 parts of a 50% aqueous sodium hydroxide solution was continuously added over 1 hour. Thereafter, the mixture was heated and stirred for 1 hour to synthesize a phosphorus-containing epoxy resin DOPO having a phosphorus content of 6.7%.

(Sample preparation)
The above materials were mixed using a mixer according to the formulation shown in Table 1 or Table 2 to prepare photosensitive thermosetting resin compositions according to the respective Examples and Comparative Examples. In this blending ratio, the standard of parts by mass of each component is 100 parts by mass of the sum of (A) + (B) + (C) + (D) + (E) (base resin composition). .

Using the resulting photosensitive thermosetting resin composition, an insulating protective film having a film thickness of 25 μm is formed on both sides of a substrate for printed wiring boards (polyimide manufactured by Toray DuPont Co., Ltd., trade name KAPTON 100V, film thickness 25 μm) did. The insulating protective film was formed by a method in which a photosensitive thermosetting resin composition was applied to a substrate and cured one by one. The curing conditions for the solder resist composition were a method of sequentially performing pre-cure (75 ° C., 25 min) → exposure (UV irradiation, 300 mJ / cm ² ) → post-cure (150 ° C., 15 min).

(Sample evaluation method)
Flame retardancy is determined by underwriters laboratories Inc. of the United States. The evaluation was made by a method based on the 94 UL V test of the flame retardant test standard of the polymer material (abbreviated as UL). Whether or not to pass the V-0 level is determined in accordance with ASTM D 3801, IEC 707, or ISO 1210, in accordance with the 20 mm vertical combustion test described in TEST FOR FLAMABILITY OF PLASTIC MATERIALS-UL94 (JULY 29, 1997). , And evaluated according to the classification described in the literature.

  For the surface bleed, the surface of the film was wiped with ethanol after being completely cured, and the surface bleed was judged to be acceptable if it was not colored. In Table 1 and Table 2, the pass is indicated by ◯ and the failure is indicated by x.

  Folding resistance was determined by forming a coating film of a photosensitive thermosetting resin composition on both sides having a film thickness of 25 μm, a length of 125 mm, and a width of 13 mm, and curing the film, and then the sample once at an angle of 180 °. A case where the cured film was not peeled off from the base material PI after being folded in half and returned to bend was regarded as acceptable. In Table 1 and Table 2, the pass is indicated by ◯ and the failure is indicated by x.

Developability is determined by jetting a developer (an aqueous solution of sodium carbonate (Na ₂ CO ₃ ) having a concentration of 1.0 mass%) at a liquid temperature of 30 ° C. and a spray pressure of 0.10 MPa for 30 minutes. A sample of 5 cm was accepted. In Table 1 and Table 2, the pass is indicated by ◯ and the failure is indicated by x.

(Evaluation results)
The results of the above evaluation are shown in Tables 1 and 2.
The insulating protective films produced according to Examples 1 to 8 had high flame resistance satisfying the UL standard, and were also excellent in folding resistance, bleed-out resistance, and developability.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for forming a protective film for a printed wiring board used for various electronic devices and electric devices.

Claims (2)

(A) carboxy-modified epoxy (meth) acrylate resin and (B) 6-H-dibenzo [c, e] [1,2] oxaphosphorin-6- [2,5-bis (oxiranylmethoxy) phenyl ] -6-oxide, (C) a photopolymerization initiator, (D) a diluent, (E) a curing agent, (F) melamine polyphosphate, and (G) aluminum hydroxide,
The component (B) is included so that the phosphorus content derived from the component (B) in the resin composition comprising the components (A) to (E) is 1.0 to 2.0% by mass, The component (F) is included so that the phosphorus content derived from the component (F) is 1.5 to 2.5% by mass with respect to 100 parts by mass of the resin composition composed of the components (A) to (E). The photosensitive thermosetting resin composition is characterized in that the component (G) is contained in an amount of 30 to 50 parts by mass with respect to 100 parts by mass of the resin composition comprising the components (A) to (E). object.   An insulating protective film obtained by curing the photosensitive thermosetting resin composition according to claim 1.