JP2013068867A - Photosensitive resin composition, and printed wiring board and reflection sheet having cured coating of photosensitive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive resin composition, in which a margin for a preliminary drying time and a shelf time after preliminary drying can be ensured for a long period of time without impairing hardness of a coating film and solder heat resistance, and sticking to a negative film after exposure can be prevented.SOLUTION: The photosensitive resin composition comprises (A) a carboxyl group-containing photosensitive resin, (B) a crystalline epoxy compound having a melting point of 130°C or higher and 150°C or lower, (C) a solvent, (D) a photopolymerization initiator and (E) a reactive diluent.

Description

  The present invention relates to a photosensitive resin composition using a crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower as a curing agent, and a printed wiring board and a reflective sheet having the cured product, in particular, preliminary drying. The present invention relates to a photosensitive resin composition that has an excellent time margin and can ensure a long standing time after preliminary drying.

  Printed wiring boards and flexible wiring boards are used to form a conductive circuit pattern on a board and to mount electronic components on the soldering lands of the pattern by soldering. The circuit parts excluding the soldering lands are It is coated with a solder resist film as a permanent protective film. This prevents solder from adhering to unnecessary parts when soldering electronic components to printed wiring boards and flexible wiring boards, and circuit conductors are directly exposed to air and corroded by oxidation and humidity. Is prevented.

  To coat a printed wiring board and a flexible wiring board with a solder resist film, after the curable resin composition for solder resist is coated on the substrate, and before the coating film is thermally cured, the curability for the coated solder resist is applied. In order to volatilize the solvent from the resin composition and make the surface of the coating film tack-free, a preliminary drying step is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes.

  On the other hand, the process of coating the printed wiring board and the flexible wiring board with the solder resist film is effective for mass production. The preliminary drying process and the subsequent development process and thermosetting process are both transport means such as a conveyor. It is done continuously using. Accordingly, when trouble occurs in the preliminary drying process line, and the line is urgently stopped, it takes a predetermined time to recover. Therefore, the substrate being preliminarily dried has a predetermined time (for example, about 15 to 60 minutes). ) The above is preliminarily dried. Then, during the preliminary drying, not only the volatilization of the solvent, but also the curable resin of the curable resin composition for solder resist and the epoxy compound as the curing agent react, resulting in an alkali of the curable resin composition. There was a problem that the solubility in an aqueous solution was lowered and the desired development could not be performed in the development process.

  Furthermore, as described above, since the preliminary drying process and the subsequent development process and thermosetting process are all performed continuously, if the solder resist film coating process is stopped on a closed day, the preliminary drying is completed. The lot after the development process may be left at room temperature during the holiday. Then, while pre-drying and leaving at room temperature, the reaction between the curable resin of the curable resin composition for solder resist and the epoxy compound as the curing agent proceeds in the same manner as above, and the curable resin There was a problem that the solubility of the composition in an alkaline solution was lowered, and the desired development could not be performed in the development process.

  Therefore, (A) a photocurable resin containing a urethane resin having a carboxyl group and an ethylenically unsaturated double bond in the molecule, (B) a photopolymerization initiator, and (C) a blocked isocyanate as a thermosetting component. Light which is a thermosetting resin composition and contains, as the thermosetting component (C), a combination of (C-1) blocked isocyanate and (C-2) epoxy resin, preferably a solid epoxy resin at room temperature. A curable / thermosetting resin composition has been proposed (Patent Document 1). In Patent Document 1, if a solid epoxy resin is dispersed in a fine particle form in a photocurable / thermosetting resin composition before curing, the pot life of the photocurable / thermosetting resin composition is increased. Combined with the action and effect of using the blocked isocyanate, the storage stability of the composition can be further improved.

  However, in Patent Document 1, an increase in the viscosity increase rate of the ink during storage can be suppressed to some extent under an atmosphere of 50 ° C., but after applying the photocurable / thermosetting resin composition on the substrate, When the pre-drying condition is left for 60 hours or more in an atmosphere of 60-80 ° C., which is the pre-drying condition, or when it is left at room temperature for a long time after the pre-drying, there is still a problem that the desired development cannot be performed.

JP 2009-185182 A

  In view of the above circumstances, the object of the present invention is to secure a margin for predrying time and a standing time after predrying for a long time without impairing coating film hardness and solder heat resistance, and to adhere to a negative film during exposure. It aims at providing the photosensitive resin composition which can be prevented.

  Embodiments of the present invention include (A) a carboxyl group-containing photosensitive resin, (B) a crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower, (C) a solvent, (D) a photopolymerization initiator, (E) reaction It is a photosensitive resin composition characterized by containing a photosensitive diluent.

  In this embodiment, the crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is difficult to dissolve in an atmosphere of 60 ° C. to 80 ° C. which is the temperature of preliminary drying. Present in the composition. Furthermore, this epoxy compound has poor solubility in the solvent as the component (C). Therefore, it is considered that the reactivity between the carboxyl group-containing photosensitive resin as the component (A) and the epoxy compound is lowered in the preliminary drying step. On the other hand, at about 150 ° C., which is the temperature of the post-cure process, this epoxy compound is softened and melted, so that it is considered that a cross-linking curing reaction occurs with the carboxyl group-containing photosensitive resin as the component (A).

  In an embodiment of the present invention, the (B) crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is contained in an amount of 60 parts by mass or more with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. The photosensitive resin composition.

（式中、R^１、R^２、R^３、R^４は、それぞれ独立して、水素原子、メチル基またはｔ‐ブチル基を示す。）であることを特徴とする感光性樹脂組成物である。 In an aspect of the present invention, the (B) crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is represented by the following general formula (1):

(Wherein R ¹ , R ² , R ³ , and R ⁴ each independently represents a hydrogen atom, a methyl group, or a t-butyl group). .

  In this embodiment, the crystalline epoxy compound of the general formula (1) has a melting point in the range of 138 ° C. to 145 ° C., and the lower limit of the melting point is even higher. Therefore, it is more difficult to dissolve in an atmosphere of 60 ° C. to 80 ° C., and it is more hardly soluble in the solvent as the component (C).

  An aspect of the present invention is a photosensitive resin composition, wherein the (A) carboxyl group-containing photosensitive resin has an aromatic ring.

  In an embodiment of the present invention, the solvent (C) is at least one selected from the group consisting of diethylene glycol monoethyl ether acetate (EDGAC), dipropylene glycol monomethyl ether (DPM) and aromatic hydrocarbons. It is the photosensitive resin composition characterized.

  An embodiment of the present invention is a photosensitive resin composition further comprising (F) titanium oxide.

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

  According to the aspect of the present invention, since the reactivity between the carboxyl group-containing photosensitive resin and the epoxy compound is reduced under the temperature condition of the preliminary drying, the margin of the preliminary drying time and the standing time after the preliminary drying are prolonged. It can be secured. Therefore, even if the conveying means in the preliminary drying process stops due to a trouble and the preliminary drying time becomes longer than the scheduled time, the expected development is possible, and the lot after the preliminary drying is completed at room temperature for a long time. Even if left unattended, the desired development can be carried out smoothly. Furthermore, since the melting point of the crystalline epoxy compound is 150 ° C. or less, in the post-cure process, this epoxy compound undergoes a cross-linking curing reaction with the carboxyl group-containing photosensitive resin, thereby improving the solder heat resistance and the coating film hardness. You can get things.

  According to the aspect of the present invention, the crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is contained in an amount of 60 parts by mass or more with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, thereby providing a margin for preliminary drying time. While being able to prolong, it can improve solder heat resistance and coating-film hardness more.

  According to the aspect of the present invention, by using the compound of the general formula (1) as the crystalline epoxy compound, the reactivity between the carboxyl group-containing photosensitive resin and the epoxy compound can be increased under the pre-drying temperature condition. Since it further decreases, the margin of the preliminary drying time can be prolonged, and the lot after preliminary drying can be left at room temperature for a longer period. Moreover, according to the aspect of this invention, the solder heat resistance and hardness of hardened | cured material improve reliably because a carboxyl group-containing photosensitive resin has an aromatic ring.

  Next, the photosensitive resin composition of the present invention will be described. The photosensitive resin composition of the present invention includes (A) a carboxyl group-containing photosensitive resin, (B) a crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower, (C) a solvent, (D) a photopolymerization initiator, (E) A photosensitive resin composition containing a reactive diluent. Each of the above components is as follows.

(A) Carboxyl group-containing photosensitive resin The carboxyl group-containing photocurable resin is not particularly limited, and examples thereof include a carboxyl group-containing resin having one or more photosensitive unsaturated double bonds. As an example of the component (A), a radical polymerizable unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid is allowed to react with at least a part of the epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in one molecule. An unsaturated monocarboxylic oxide epoxy resin obtained by obtaining an unsaturated monocarboxylic oxide epoxy resin and reacting the generated hydroxyl group with a polybasic acid or an anhydride thereof may be mentioned. Moreover, the compound which made the glycidyl compound which has one or more radically polymerizable unsaturated groups and an epoxy group react further with the carboxyl group which said polybasic acid modification | denaturation monocarboxylic oxidation epoxy resin has can also be mentioned.

  Any polyfunctional epoxy resin can be used as long as it is a bifunctional or higher functional epoxy resin. Although the epoxy equivalent of a polyfunctional epoxy resin is not specifically limited, 1000 or less are preferable and 100-500 are especially preferable. Examples of the polyfunctional epoxy resin include biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, rubber modified epoxy resin such as silicone modified epoxy resin, ε-caprolactone modified epoxy resin, bisphenol A type, bisphenol. Phenol type novolak type epoxy resin such as F type, bisphenol AD type, cresol novolak type epoxy resin such as о-cresol novolak type, bisphenol A novolak type epoxy resin, cyclic aliphatic 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, phenols and phenolic hydroxyl group Examples thereof include condensate type epoxy resins with aromatic aldehydes. Moreover, what introduce | transduced halogen atoms, such as Br and Cl, to these resin can also be used. Among these, a polyfunctional epoxy resin having an aromatic ring is preferable from the viewpoint of solder heat resistance and hardness of the cured product. These epoxy resins may be used alone or in combination of two or more.

  The radically polymerizable unsaturated monocarboxylic acid to be used is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, acrylic acid, methacrylic acid (hereinafter referred to as (meth) acrylic acid). And acrylic acid is particularly preferred. The reaction method of an epoxy resin and radically polymerizable unsaturated monocarboxylic acid is not specifically limited, For example, the reaction method which heats an epoxy resin and acrylic acid in a suitable diluent is mentioned.

  The polybasic acid or polybasic acid anhydride reacts with a hydroxyl group generated by the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid to give the resin a free carboxyl group. The polybasic acid to be used 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.

  Further, as described above, in the carboxyl group-containing photosensitive resin of the present invention, one or more radically polymerizable unsaturated groups and an epoxy group are added to the carboxyl group of the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin. The photosensitivity may be further improved by further introducing a radical polymerizable unsaturated group by reacting the glycidyl compound possessed.

  This photosensitized resin has higher photopolymerization reactivity because the radical polymerizable unsaturated group is bonded to the side chain of the polymer backbone of the precursor resin by the reaction of the glycidyl compound. , Has excellent photosensitive properties. 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, and the like. In addition, you may have multiple glycidyl groups in 1 molecule. The above-mentioned compounds having one or more radically polymerizable unsaturated groups and epoxy groups may be used alone or in combination of two or more.

  The lower limit of the acid value of the carboxyl group-containing photosensitive resin is 30 mg KOH / g, preferably 40 mg KOH / g, from the viewpoint of reliable alkali development. On the other hand, the upper limit of the acid value is 200 mgKOH / g from the viewpoint of preventing dissolution of the exposed area with an alkali developer, and 150 mgKOH / g is preferable from the viewpoint of preventing moisture resistance of the cured product and preventing deterioration of electrical characteristics.

  The lower limit of the weight average molecular weight of the carboxyl group-containing photosensitive resin is 3000, preferably 5000, from the viewpoint of the toughness of the cured product and the touch drying property. On the other hand, the upper limit of the weight average molecular weight is 200,000, preferably 50,000 from the viewpoint of compatibility with the reactive diluent as component (E) and smooth alkali developability. The double bond equivalent of the carboxyl group-containing photosensitive resin is 200 to 1000 g / eq from the viewpoint of photosensitivity, and 400 to 800 g / eq is preferable from the viewpoint of the balance between photosensitivity and flexibility.

  Examples of commercially available carboxyl group-containing photosensitive resins include ZFR-1122, FLX-2089, ZAR-1035, ZCR-1642H (manufactured by Nippon Kayaku Co., Ltd.), Cyclomer P (ACA). Z-250, Cyclomer P (ACA) Z-300 (manufactured by Daicel Chemical Industries, Ltd.), Lipoxy SP-4621 (manufactured by Showa Polymer Co., Ltd.), and the like. These resins may be used alone or in combination of two or more.

(B) Crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower The epoxy compound is for obtaining a cured product having a sufficient mechanical strength by increasing the crosslinking density. The epoxy compound used in the present invention is a crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower and has poor solubility in the solvent as the component (C). In the present specification, “slightly soluble” means that a sample liquid (concentration of crystalline epoxy compound: 1.0% by mass) obtained by adding a crystalline epoxy compound to the solvent as component (C) in a dryer at 80 ° C. For 12 hours, and after stirring for 12 hours in a dryer at 80 ° C., the sample solution is taken out of the dryer, left at room temperature (25 ° C.) for 72 hours, and the crystal of the sample solution is visually observed. It means that the dissolution state of the crystalline epoxy compound is observed and the amount of the crystalline epoxy compound dissolved is 5% by volume or less. The solvent to which the crystalline epoxy compound is added is not particularly limited, but from the viewpoint of printability and drying properties, as described later, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether (DPM), which is the solvent of component (C), will be described later. ) And aromatic hydrocarbons are preferred. The crystalline epoxy compound is an epoxy compound having a relatively low molecular weight (for example, a molecular weight of 200 to 1000) that is solid at room temperature (25 ° C.).

  The melting point of the epoxy compound used in the present invention is 130 ° C. or higher and 150 ° C. or lower, and the carboxyl group-containing photosensitive resin is used in the post-cure process while further reducing the reactivity with the carboxyl group-containing photosensitive resin in the preliminary drying process. The melting point is preferably from 138 ° C. to 145 ° C.

  Although it will not specifically limit if it is a crystalline epoxy compound whose melting | fusing point is 130 degreeC or more and 150 degrees C or less, For example, following General formula (1)

(In the formula, R ¹ , R ² , R ³ , and R ⁴ each independently represents a hydrogen atom, a methyl group, or a t-butyl group). These compounds may be used alone or in combination of two or more.

  The blending amount of the crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is not particularly limited, but the lower limit is 100 parts by weight of the carboxyl group-containing photosensitive resin, while prolonging the margin of the preliminary drying time, The amount is preferably 60 parts by mass from the viewpoint of improving the solder heat resistance and coating film hardness of the cured product, more preferably 85 parts by mass from the viewpoint of insulation reliability, and particularly preferably 120 parts by mass from the viewpoint of increasing the glass transition temperature. On the other hand, the upper limit is preferably 180 parts by mass from the viewpoint of dispersibility during production, more preferably 160 parts by mass from the viewpoint of developability, and particularly preferably 150 parts by mass from the viewpoint of coating properties.

(C) Solvent The solvent is used to adjust the viscosity and drying property of the thermosetting resin composition. Examples of the solvent include organic solvents. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone, 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, butyl cellosolve acetate, carbitol acetate, butylcarbi Examples include esters such as tall acetate and diethylene glycol monoethyl ether acetate. Among these, from the viewpoint of workability, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether (DPM), and aromatic hydrocarbons (for example, petroleum naphtha) are preferable. These solvents may be used alone or in combination of two or more. Although the compounding quantity of a solvent is not specifically limited, 40-500 mass parts is preferable with respect to 100 mass parts of (A) carboxyl group-containing photosensitive resin.

(D) Photopolymerization initiator
The photopolymerization initiator is not particularly limited as long as it is generally used. For example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethyl Aminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2 -Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-pheny Benzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone 2,4-dimethylthioxanthone, 2,4 diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, P-dimethylaminobenzoic acid ethyl ester, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,4 6-trimethylbenzoyl) -phenylphosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone, ethanone, - [9-ethyl-6- (2-methylbenzoyl) -9H- carbazol-3-yl] -, 1-(O-acetyl oxime), and the like. These may be used alone or in combination of two or more. The compounding quantity of a photoinitiator is 2-25 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 8-20 mass parts is preferable.

(E) Reactive diluent The reactive diluent is, for example, a photopolymerizable monomer and a compound having at least two polymerizable double bonds per molecule. The reactive diluent is used to sufficiently cure the carboxyl group-containing photosensitive resin and obtain a cured product having acid resistance, heat resistance, alkali resistance, and the like.

  The reactive diluent is not particularly limited as long as it is the above compound. For example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate , Polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) Acrylate, ethylene oxide modified di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipenta Thritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified Examples include dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used alone or in combination of two or more. The compounding quantity of a reactive diluent is 2-100 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin, and 10-90 mass parts is preferable.

  In the photosensitive resin composition of this invention, you may mix | blend a flame retardant and a coloring agent as needed in addition to the said component.

  By blending a flame retardant with the photosensitive resin composition of the present invention, flame retardancy can be imparted to the cured product. A flame retardant is not specifically limited, A well-known thing can be used, For example, poorly soluble flame retardants, such as aluminum tris diethyl phosphinate, can be mentioned.

  It can color by mix | blending a coloring agent with the photosensitive resin composition of this invention. In the case of coloring white, a white colorant, for example, titanium oxide is blended. Examples of titanium oxide include anatase type titanium oxide and rutile type titanium oxide. Anatase-type titanium oxide has a higher whiteness than rutile-type titanium oxide, but has photocatalytic activity and may cause discoloration of the resin in the photosensitive resin composition. In contrast, rutile type titanium oxide is preferable in that it has almost no photocatalytic activity and can prevent discoloration of the resin. The compounding quantity of a titanium oxide is 30-800 mass parts with respect to 100 mass parts of carboxyl group-containing photosensitive resin, Preferably it is 50-500 mass parts.

  In addition, when coloring the photosensitive resin composition of the present invention in a color other than white, for example, black, blue, yellow, etc., instead of the white colorant, other colorants such as black colorant, You may mix | blend a blue colorant, a yellow colorant, etc.

  In the photosensitive resin composition of the present invention, various additive components such as antifoaming agents, various additives, extender pigments, and the like can be appropriately blended in addition to the above-described components as necessary.

  A well-known thing can be used for an antifoamer, For example, a silicone type, an olefin type copolymer, an acrylic type etc. can be mentioned. Examples of the various additives include dispersants such as coupling agents such as silane, titanate, and alumina, boron trifluoride-amine complex, dicyancyanide (DICY) and its derivatives, organic acid hydrazide, diaminomaleonitrile (DAMN). ) And derivatives thereof, melamine and derivatives thereof, guanamine and derivatives thereof, latent curing agents such as amine imide (AI) and polyamines, metal salts of acetylacetone such as acetylacetonate Zn and acetylacetonate Cr, enamine, tin octylate, Examples include quaternary sulfonium salts, triphenylphosphine, imidazoles, imidazolium salts, and thermosetting accelerators such as triethanolamine borate.

  The method for producing the photosensitive resin composition of the present invention described above is not limited to a specific method. For example, after blending the above components at a predetermined ratio, at room temperature, kneading means such as a three roll, ball mill, sand mill, etc. Alternatively, it can be produced by kneading or mixing by 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.

  Below, the coating method of the above-mentioned photosensitive resin composition of this invention is demonstrated. First, the case where the photosensitive resin composition of the present invention is applied to a printed wiring board as a solder resist film will be described as an example.

  The photosensitive resin composition of the present invention produced as described above, for example, on a printed wiring board having a circuit pattern formed by etching a copper foil, screen printing method, roll coater method, bar coater method, spray coater method , A curtain flow coater method, a gravure coater method or the like is applied to a desired thickness, and a preliminary heating is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes in order to volatilize the solvent in the photosensitive resin composition Dry to form a tack-free coating. Then, the negative film which has the pattern which made translucent except the land of the said circuit pattern is closely_contact | adhered on the apply | coated photosensitive resin composition, and an ultraviolet-ray is irradiated from it. 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. Although it does not specifically limit as a dilute alkaline aqueous solution used, For example, 0.5-5% of sodium carbonate aqueous solution is mentioned. Next, the cured coating film of the desired photosensitive resin composition is formed on the printed wiring board by thermally curing the coating film by performing post-cure for 20 to 80 minutes with a hot air circulation dryer at 130 to 170 ° C. Can be formed.

  An electronic circuit unit is formed by soldering an electronic component to the printed wiring board coated with the cured coating film thus obtained by a jet soldering method, a reflow soldering method, or the like.

  Next, an example of a method for producing a reflective sheet by coating the photosensitive resin composition described above on the surface of a sheet-like base film will be described. When producing a reflective sheet, a white colorant is added to the photosensitive resin composition in order to impart a high reflectance to the reflective coating. For example, after the surface of the sheet-like base film is washed by acid treatment, the white photosensitive resin composition produced as described above is washed on the washed surface, such as a screen printing method or a spray coater method using a printing mask. It is applied to a desired thickness (for example, a thickness of 5 to 100 μm) by a known coating means. After coating, preliminary drying is performed at a temperature of about 60 to 80 ° C. for about 15 to 60 minutes to form a tack-free coating film. Next, by performing post-cure at a temperature of about 130 to 170 ° C. for 10 to 80 minutes, a target white cured coating film, that is, a reflective coating film can be formed on the surface of the sheet-like base film to produce a reflective sheet.

  The material of the sheet-like base film is not particularly limited. For example, polyimide, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), fluorinated ethylene / propylene copolymer (FEP), polytetrafluoroethylene (PTFE), aramid , Polyamide / imide, epoxy, polyetherimide, polysulfone, polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and the like.

  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 1-11, Comparative Examples 1-4
Each component shown in the following Table 1 is blended at the blending ratio shown in the following Table 1, mixed and dispersed at room temperature using three rolls, and used in Examples 1 to 11 and Comparative Examples 1 to 4. A functional resin composition was prepared. And the prepared photosensitive resin composition was apply | coated on the board | substrate using the test piece preparation process mentioned later, and the test piece was created. In addition, unless otherwise indicated, the compounding quantity of each component shown in following Table 1 shows a mass part.

Details of each component in Table 1 are as follows.
(A) Carboxyl group-containing photosensitive resin / ZFR-1122: manufactured by Nippon Kayaku Co., Ltd., an acid anhydride additive of bisphenol F type epoxy acrylate.
FLX-2089: Nippon Kayaku Co., Ltd., acid-modified urethane-modified epoxy methacrylate resin.
-ZAR-1035: Nippon Kayaku Co., Ltd. acid anhydride additive of bisphenol A type epoxy acrylate.
ZCR-1642H: manufactured by Nippon Kayaku Co., Ltd., an acid anhydride additive of biphenyl type epoxy acrylate.
(B) Crystalline epoxy compound YDC-1312: manufactured by Nippon Steel Chemical Co., Ltd., in general formula (1), R ¹ and R ⁴ are t-butyl groups, R ² and R ³ are hydrogen atoms Hydroquinone type epoxy resin.
Epicoat 1003: manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin (solid at room temperature (25 ° C.)), melting point 89 ° C.
YX-8800: manufactured by Mitsubishi Chemical Corporation, a polycyclic aromatic epoxy resin.
YX-4000K: manufactured by Mitsubishi Chemical Corporation, biphenyl type epoxy resin.
YSLV-120TE: Nippon Steel Chemical Co., Ltd., thioether type epoxy resin.
(D) Photopolymerization initiator SPEEDCURE TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide manufactured by LAMBSON.
Irgacure 819: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, manufactured by Ciba Specialty Chemicals.
Irgacure 369: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone manufactured by Ciba Specialty Chemicals Co., Ltd.
OXE-02: manufactured by BASF Japan, Etanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime).
(E) Reactive diluent, EBECRYL 8405: manufactured by Daicel Cytec Co., Ltd., tetrafunctional modified urethane acrylate 80% by mass + hexamethylene diol diacrylate (HDDA) 20% by mass.
EBECRYL 3708: a bifunctional modified epoxy acrylate manufactured by Daicel-Cytec.

  In addition, OP-935 is a trisdiethylphosphinate aluminum manufactured by Clariant Japan Co., Ltd., AC-2000 is an olefin copolymer manufactured by Kyoeisha Chemical Co., Ltd., and DICY-7 is a dicyancyanide manufactured by Mitsubishi Chemical Corporation. Latent curing agent, melamine is also a latent curing agent. Epicoat 850 is a bisphenol A type epoxy resin (liquid at normal temperature (25 ° C.)) manufactured by Mitsubishi Chemical Corporation.

Test piece preparation process (for solder heat resistance and coating film hardness evaluation)
A printed wiring board having a circuit pattern formed on a copper clad laminate (FR-4, 1.6 t, conductor thickness 35 μm) was surface-treated with dilute sulfuric acid (3%), and then prepared by the screen printing method as described above. The photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 were respectively applied, and after the application, preliminary drying was performed at 80 ° C. for 20 minutes in a BOX furnace. After the preliminary drying, a negative film having a pattern in which light is transmitted except for the land of the circuit pattern is brought into close contact with the coating film, and an ultraviolet ray having a wavelength of 360 nm is applied to the film by an exposure apparatus (HMW-680GW manufactured by Oak Co.). After exposure to cm ^2, development was performed with a 1% sodium carbonate developer at 30 ° C. (development pressure 0.2 MPa, 60 seconds) (photographic development method). After development, a cured coating film was formed on the printed wiring board by curing at 150 ° C. for 60 minutes in a BOX furnace. The thickness of the cured coating film was 20-23 μm.

Evaluation (1) Control width after preliminary drying After the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 prepared as described above were applied to the printed wiring board, the temperature was 80 in a BOX furnace. Preliminary drying was performed at a temperature of C for a predetermined time. The predetermined time was 20 minutes, 30 minutes, 40 minutes,... After preliminary drying, development was performed by the photographic development method. After development, the residue on the copper foil in each preliminary drying time from 20 minutes to 260 minutes was visually observed, and the preliminary drying time at which the residue was generated was defined as the management width after preliminary drying.

(2) Allowable time after preliminary drying After the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 prepared as described above were applied to the printed wiring board, the temperature was 80 in a BOX furnace. Preliminary drying was performed at 20 ° C. for 20 minutes. Then, it was left at room temperature (25 ° C.). The standing time at room temperature (25 ° C.) was 24 hours, 48 hours,... After standing for the predetermined time, development was performed by the photographic development method. After development, the residue on the copper foil in each standing time from 24 hours to 120 hours was visually observed, and the standing time when the residue was generated was defined as the time allowed to stand after preliminary drying.

(3) Film sticking property After applying the photosensitive resin compositions of Examples 1 to 11 and Comparative Examples 1 to 4 prepared as described above to the printed wiring board, the temperature was 80 ° C. for 20 minutes in a BOX furnace. Was pre-dried. Thereafter, the negative film was brought into close contact with the coating film, and an ultraviolet ray having a wavelength of 360 nm was exposed to 500 mJ / cm ² with an exposure apparatus (HMW-680GW manufactured by Oak Co.). The sticking property of the coating film to the negative film during the exposure was evaluated according to the following criteria.
A: After the negative film is peeled off, there is no trace of sticking to the coating film.
○: After peeling off the negative film, some sticking marks remain on the coating film.
Δ: After peeling off the negative film, a sticking mark remains on the coating film.
X: The coating film adheres to the negative film after peeling.

(4) Solder heat resistance The cured coating film of each test piece prepared as described above is immersed in a solder bath at 260 ° C. for 30 seconds in accordance with the test method of JIS C-6481, and then the peeling test with a cellophane tape is set as one cycle. The coating state after repeating this 1 to 3 times was visually observed and evaluated according to the following criteria.
A: No change is observed in the coating film even after 3 cycles.
○: Only a slight change is observed in the coating film after repeating 3 cycles.
(Triangle | delta): A change is recognized by the coating film after 2 cycles repetition.
X: Peeling is recognized in the coating film after repeating 1 cycle.

(5) Coating film hardness According to the test method of JIS K-5600-5-4, a 3B to 9H pencil sharpened so that the tip of the core is flattened on the cured coating film on the copper foil is about 45 °. The hardness of the pencil at which the coating film did not peel off was recorded.

  Further, the crystalline epoxy compound “YDC-1312” used in Examples 1 to 11, the crystalline epoxy compound “YX-8800” used in Comparative Example 1, and the crystalline epoxy compound “YX-4000K used in Comparative Example 2”. Table 2 below shows the solubility in the solvent and the melting point of the crystalline epoxy compound “YSLV-120TE” used in Comparative Example 3 and the crystalline epoxy compound “Epicoat 850” used in Comparative Example 4. “Solvesso # 150” in Table 2 is an aromatic hydrocarbon (manufactured by ExxonMobil).

In addition, the solubility evaluation method of each crystalline epoxy compound of Table 2 is as follows.
1 g of each crystalline epoxy compound was taken in a screw mouth bottle, and 9 g of each solvent shown in Table 2 was added thereto to prepare a 10% by mass sample solution. Similarly, 0.5 g of each crystalline epoxy compound was taken, and 9.5 g of each solvent described in Table 2 was added thereto to prepare a 5 mass% sample solution. Similarly, 0.1 g of each crystalline epoxy compound was taken, and 9.9 g of each solvent shown in Table 2 was added thereto to give a 1% by mass sample solution. The prepared sample solution was left in an oven at 80 ° C. for 12 hours, stirred well, and then left in an oven at 80 ° C. for 12 hours. Thereafter, the sample solution was taken out from the oven and allowed to stand at room temperature (25 ° C.) for 1 hour to confirm that the temperature of the sample solution was lowered and the state of the sample solution. The transparent sample solution was further allowed to stand at room temperature (25 ° C.) for 72 hours, and the dissolution state of the crystalline epoxy compound in the sample solution was visually observed.
A: The crystalline epoxy compound is not dissolved.
○: The crystalline epoxy compound is dissolved, but the dissolved amount is 5% by volume or less.
(Triangle | delta): The amount of dissolution of a crystalline epoxy compound is more than 5 volume% and 50 volume% or less.
X: Dissolution amount of the crystalline epoxy compound exceeds 50% by volume.

  Table 3 shows the results of Examples 1 to 11 and Comparative Examples 1 to 4 after the pre-drying control width, the time allowed to stand after the pre-drying, the film sticking property, the solder heat resistance, and the coating film hardness.

  As shown in Table 3, in Examples 1 to 11 in which a crystalline epoxy compound having a melting point of 138 to 145 ° C. was blended, the control width after preliminary drying without impairing film sticking property, solder heat resistance and coating film hardness 220 to 260 minutes, the allowed time after preliminary drying was 120 hours or more, and both the control width after preliminary drying and the allowable time after preliminary drying were prolonged. Therefore, in Examples 1-11, the margin of the preliminary drying time and the leaving time after preliminary drying were able to be ensured for a long time. Moreover, from Table 2, the crystalline epoxy compound having a melting point of 138 to 145 ° C. was hardly soluble in any of diethylene glycol monoethyl ether acetate, DPM and Solvesso as the component (C).

  On the other hand, in Comparative Examples 1 to 3 in which a crystalline epoxy compound having a melting point of 125 ° C. or lower is blended and in Comparative Example 4 in which an epoxy compound that is not crystalline is blended, the control range after preliminary drying is 60 to 60%. In the range of 100 minutes, the allowed standing time after preliminary drying was 72 hours, and both the control width after preliminary drying and the allowed standing time after preliminary drying were considerably shorter than in Examples 1-11. Moreover, from Table 2, the crystalline epoxy compound having a melting point of 125 ° C. or less used in Comparative Examples 1 to 3 is either or both of (C) component diethylene glycol monoethyl ether acetate, DPM and Solvesso. It did not show poor solubility.

  Further, from Example 1 and Example 2, when the crystalline epoxy compound having a melting point of 138 to 145 ° C. is contained in an amount of 60 parts by mass or more with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, film sticking property, solder While reliably improving heat resistance and coating film hardness, the control range after preliminary drying could be extended. Further, from Example 4, even when an epoxy compound having a low melting point of 89 ° C. and a crystalline epoxy compound having a melting point of 138 to 145 ° C. are blended, both the control width after preliminary drying and the time allowed to stand after preliminary drying are prolonged. did it.

  The photosensitive resin composition of the present invention can ensure a long margin for pre-drying time and a standing time after pre-drying without losing the coating film hardness and solder heat resistance. For example, it is highly useful in fields such as solder resist, solar cell backsheet coating, and LED backsheet coating.

Claims (8)

  (A) A carboxyl group-containing photosensitive resin, (B) a crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower, (C) a solvent, (D) a photopolymerization initiator, and (E) a reactive diluent. The photosensitive resin composition characterized by the above-mentioned.   2. The crystalline epoxy compound (B) having a melting point of 130 ° C. or higher and 150 ° C. or lower is contained in an amount of 60 parts by mass or more with respect to 100 parts by mass of the (A) carboxyl group-containing photosensitive resin. The photosensitive resin composition as described. The (B) crystalline epoxy compound having a melting point of 130 ° C. or higher and 150 ° C. or lower is represented by the following general formula (1)

^{3. wherein} R ¹ , R ² , R ³ and R ⁴ each independently represents a hydrogen atom, a methyl group or a t-butyl group. Photosensitive resin composition.   The photosensitive resin composition according to claim 1, wherein the (A) carboxyl group-containing photosensitive resin has an aromatic ring.   2. The photosensitive resin according to claim 1, wherein the solvent (C) is at least one selected from the group consisting of diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, and aromatic hydrocarbons. Composition.   Furthermore, (F) Titanium oxide is contained, The photosensitive resin composition of any one of the Claims 1 thru | or 5 characterized by the above-mentioned.   The printed wiring board which has a hardened film of the photosensitive resin composition of any one of Claims 1 thru | or 6.   The reflective sheet which has a cured film of the photosensitive resin composition of any one of Claims 1 thru | or 6.