JP5352340B2 - Photosensitive resin composition, solder resist composition for printed wiring board, and printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white liquid photosensitive resin composition having reduced discoloring of a white coating film and deterioration in reflectance due to UV irradiation and a thermal history, and forming a pattern with a low amount of exposure. <P>SOLUTION: The white photo-curing resin composition contains: (A) a carboxyl group-containing photosensitive resin having no aromatic ring; (B) photopolymerization initiator; (C) a diluent; (D) titanium dioxide; and (E) one or more kinds of epoxy compounds selected from epoxy compounds represented by formulas (1), (2), (3) and (4). <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a photosensitive resin composition, a solder resist composition for a printed wiring board, and a printed wiring board.

  A printed wiring board is for mounting a circuit pattern on a circuit board by soldering an electronic component to the soldering land of the pattern, and the circuit part excluding the soldering land is permanent. It is coated with a solder resist film as a protective 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. . In recent years, printed wiring boards have also been used for the purpose of reflecting plates of light sources such as LEDs.

  With the demand for higher wiring density (miniaturization) of printed wiring boards, solder resist compositions are also required to have high resolution and high precision. A liquid photo solder resist method (photographic development method) that is excellent in accuracy and coverage of conductor edge portions has been proposed. Such solder resist compositions are described in, for example, Patent Documents 1 to 6.

  In addition, an alkali development type photo solder resist composition that can be developed with a dilute alkaline aqueous solution has been proposed (Patent Document 7).

  These liquid solder resist compositions are provided with photosensitivity and developability in a dilute alkaline aqueous solution by introducing a carboxyl group into epoxy acrylate. However, this composition further contains an epoxy compound as a thermosetting component in order to normally heat-cure after the coating film is exposed and developed to form a desired resist pattern, A heat treatment for reacting the carboxyl group introduced into the epoxy acrylate is performed to form a resist film having excellent adhesion, hardness, heat resistance, electrical insulation and the like. In this case, generally, an epoxy resin curing agent is used together with the epoxy resin.

  However, particularly in the case of a white solder resist, when the coating film is heated and cured, discoloration occurs and the color changes, resulting in a decrease in light reflectance. Furthermore, when a white solder resist is used as a reflective material such as an LED for a long time, deterioration over time and deterioration of reflectance due to light and heat become problems, and a solution has been demanded. On the other hand, the solder resist composition needs to form a resist pattern with a relatively low exposure amount, making it more difficult to solve the deterioration over time and the reflectance due to light and heat.

  In order to solve this problem, the present applicants disclosed in Patent Documents 8 and 9 a photosensitive resin composition mainly composed of a photosensitive resin using alicyclic skeleton epoxy as a raw material. However, even this composition was not sufficient in deterioration over time.

  In Patent Document 10, a carboxyl group-containing photosensitive resin composition having no aromatic ring has been reported, but it has not been sufficient for solving the reduction in reflectance.

JP-A-50-144431 JP 49-5923 A JP-A 61-243869 JP 2001-233842 A JP 2001-302871 A JP 2003-280193 A JP 2006-259150 A JP2008-211036 Japanese Patent Application No. 2008-216320 JP2008-134621

  An object of the present invention is to provide a liquid photosensitive resin composition that is less susceptible to discoloration of the white coating film due to UV irradiation and thermal history when used as a reflective material such as an LED, and a decrease in reflectance, and can be patterned with a low exposure Is to provide things.

The white light curable resin composition according to the present invention is
(A) a carboxyl group-containing photosensitive resin having no aromatic ring,
(B) a photopolymerization initiator,
(C) Diluent,
(D) Titanium oxide and (E) One or more epoxy compounds selected from epoxy compounds represented by the following general formulas (1), (2), (3), (4) and (5) It is characterized by containing.

（一般式（１）、（２）、（３）、（４）および（５）において、Ｒ１、Ｒ２、Ｒ３、Ｒ４、Ｒ５、Ｒ６、Ｒ７およびＲ８は、各々独立に、メチル基、水素原子またはｔ−ブチル基である。）

(In the general formulas (1), (2), (3), (4) and (5), R1, R2, R3, R4, R5, R6, R7 and R8 are each independently a methyl group, a hydrogen atom, Or a t-butyl group.)

  Moreover, this invention relates to the soldering resist composition for printed wiring boards characterized by consisting of the said photosensitive resin composition.

  The present invention also relates to a printed wiring board on which a solder resist made of a cured product of the composition is formed.

  The white coating film formed from the photosensitive resin composition of the present invention was less susceptible to discoloration and reflectance reduction due to UV irradiation and thermal history, and was able to form a pattern with a low exposure.

Hereinafter, each component of the composition of the present invention will be described.
((A) carboxyl group-containing photosensitive resin having no aromatic ring)
(A) will not be limited to a specific thing, if it is resin which has a carboxyl group which does not have an aromatic ring. Either a photosensitive carboxyl group-containing resin having one or more photosensitive unsaturated double bonds in itself or a carboxyl group-containing resin having no photosensitive unsaturated double bond can be used.

  As (A), for example, after reacting a radically polymerizable unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid with at least a part of the epoxy group of an alicyclic skeleton epoxy resin having two or more epoxy groups in the molecule And a product obtained by reacting a produced hydroxyl group with a polybasic acid anhydride.

  The alicyclic skeleton epoxy resin is a resin having an alicyclic skeleton, and is an epoxy resin in which the skeleton is formed by a chain of aliphatic cyclic compounds. Although there is no restriction | limiting in particular of an epoxy equivalent, Usually, 1000 or less, Preferably the thing of 100-500 is used.

  As the alicyclic skeleton epoxy resin, “EHPE-3150” (1,2-epoxy-4- (2-oxiranyl) cyclohexene adduct of 2,2-bis (hydroxymethyl) -1-butanol) manufactured by Daicel Chemical Industries, Ltd. Etc. can be illustrated.

  When these epoxy resins are reacted with radically polymerizable unsaturated monocarboxylic acid, the epoxy group is cleaved by the reaction of the epoxy group and the carboxyl group to form a hydroxyl group and an ester bond. The radical polymerizable unsaturated monocarboxylic acid to be used is not particularly limited and includes, for example, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, etc., but at least one of acrylic acid and methacrylic acid (hereinafter referred to as (meth) acrylic). It is sometimes referred to as an acid.), And acrylic acid is particularly preferable. There is no restriction | limiting in particular in the reaction method of an epoxy resin and radically polymerizable unsaturated monocarboxylic acid, For example, it can react by heating an epoxy resin and acrylic acid in a suitable diluent. Examples of the diluent include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, and 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, butyl Examples include acetates such as carbitol acetate. Examples of the catalyst include amines such as triethylamine and tributylamine, and phosphorus compounds such as triphenylphosphine and triphenylphosphate.

  In the reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid, it is preferable to react 0.7 to 1.2 equivalents of the radically polymerizable unsaturated monocarboxylic acid per 1 equivalent of the epoxy group of the epoxy resin. When at least one of acrylic acid or methacrylic acid is used, 0.8 to 1.0 equivalent is more preferably added and reacted. If the radically polymerizable unsaturated monocarboxylic acid is less than 0.7 equivalent, gelation may occur during the synthesis reaction in the subsequent step, or the stability of the resin is lowered. Further, if the radically polymerizable unsaturated monocarboxylic acid is excessive, a large amount of unreacted carboxylic acid remains, which may reduce various properties (for example, water resistance) of the cured product. The reaction between the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is preferably performed in a heated state, and the reaction temperature is preferably 80 to 140 ° C. If the reaction temperature exceeds 140 ° C, the radically polymerizable unsaturated monocarboxylic acid is likely to undergo thermal polymerization and may be difficult to synthesize, and if it is less than 80 ° C, the reaction rate will be slow, which is undesirable in actual production. There is.

  In the reaction of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid in the diluent, the blending amount of the diluent is preferably 20 to 50% with respect to the total weight of the reaction system. The reaction product of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid can be subjected to the reaction with the next polybasic acid in the form of a diluent without isolation.

  A polybasic acid or an anhydride thereof is reacted with the unsaturated monocarboxylic oxide epoxy resin which is a reaction product of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid. There is no restriction | limiting in particular as a polybasic acid or its anhydride, Either saturated and unsaturated can be used. Examples of such polybasic acids include succinic acid, maleic acid, adipic acid, citric acid, phthalic acid, tetrahydrophthalic acid, 3-methyltetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, 3-ethyltetrahydrophthalic acid, 4 -Ethyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4-ethylhexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexa Examples include hydrophthalic acid, endomethylenetetrahydrophthalic acid, methylendomethylenetetrahydrophthalic acid, trimellitic acid, pyromellitic acid, and diglycolic acid. Examples of polybasic acid anhydrides include these anhydrides. These compounds can be used alone or in combination of two or more.

  The polybasic acid or polybasic acid anhydride reacts with a hydroxyl group generated by the reaction of the above-described epoxy resin and a radically polymerizable unsaturated monocarboxylic acid, thereby giving the resin a free carboxyl group. The amount of the polybasic acid or polybasic acid anhydride to be reacted is 0.3 to 1.0 mol with respect to 1 mol of the hydroxyl group of the reaction product of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid. It is desirable that From the point that a highly sensitive resin film can be obtained at the time of exposure, the reaction is preferably performed at a ratio of 0.4 to 1.0 mol, more preferably 0.6 to 1.0 mol. When the amount is less than 0.3 mol, the dilute alkali developability of the obtained resin may be reduced. When the amount exceeds 1.0 mol, various properties (for example, water resistance) of the finally obtained cured coating film may be reduced. May decrease.

  The polybasic acid is preferably added to the unsaturated monocarboxylic oxide epoxy resin and subjected to a dehydration condensation reaction. The water produced during the reaction is preferably continuously removed from the reaction system, but the reaction is carried out in a heated state. Preferably, the reaction temperature is 70 to 130 ° C. When the reaction temperature exceeds 130 ° C., those bonded to an epoxy resin and radically polymerizable unsaturated groups of unreacted monomers may easily cause thermal polymerization, making synthesis difficult. The speed is slow, which may be undesirable in actual manufacturing.

  The acid value of the polybasic acid-modified unsaturated monocarboxylic acid epoxy resin, which is a reaction product of the polybasic acid or polybasic acid anhydride and the unsaturated monocarboxylic acid epoxy resin, is preferably 60 to 300 mgKOH / g. The acid value of the reaction product can be adjusted by the amount of the polybasic acid to be reacted.

  Although the above polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin can also be used as (A), one or more radical polymerizable unsaturated groups are present on the carboxyl group of the above polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin. It is also preferable that a radically polymerizable unsaturated group is further introduced by reacting a glycidyl compound having a group with an epoxy group to further improve the photosensitivity.

  The photosensitive resin with improved photosensitivity has a photopolymerization reaction because the radical polymerizable unsaturated group is bonded to the side chain of the polymer skeleton of the precursor photosensitive resin by the reaction of the last glycidyl compound. It has high properties and can have excellent photosensitivity. 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. These compounds may be used alone or in combination.

  The glycidyl compound is added to the polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin solution and allowed to react. Usually, 0.05 to 0.5 mol of the carboxyl group introduced into the resin. React at a rate. In consideration of the photosensitivity (sensitivity) of the photosensitive resin composition containing the obtained photosensitive resin and the above-described electrical characteristics such as the thermal management width and electrical insulation, preferably 0.1 to 0.5. Preference is given to reacting in molar proportions. The reaction temperature is preferably 80 to 120 ° C. The photosensitive resin comprising the glycidyl compound-added polybasic acid-modified unsaturated monocarboxylic oxide epoxy resin thus obtained preferably has an acid value of 45 to 250 mgKOH / g.

  The acid value of (A) is preferably in the range of 20 to 200 mgKOH / g. The weight average molecular weight of the carboxyl group-containing resin (A) is preferably in the range of 3000 to 100,000.

  Specific examples of (A) include "Cyclomer P (ACA) Z-251", "Cyclomer P (ACA)" manufactured by Daicel Chemical Industries, which is a copolymer resin containing an unsaturated double bond group and a carboxyl group. "Z-250", "Cyclomer P (ACA) Z-300", "Cyclomer P (ACA) Z-320", alicyclic epoxy resin described in Patent Document 8 ("EHPE-3150" manufactured by Daicel Chemical Industries, Ltd.) The active energy ray-curable resin reacted from (1) can be exemplified. However, as the reacted polybasic acid anhydride, one having no aromatic ring is selected.

  In the composition of the present invention, the content of (A) is preferably 10 to 50% by mass.

(B) a photopolymerization initiator,
As the photopolymerization initiator (B), an oxime initiator, 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-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-phenylbenzophenone, 4,4 -Diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethyl Thioxanthone, 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ethyl ester, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) ) -Phenylphosphine oxide and the like. These can be used alone or in combination. The amount used is preferably 5 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the photosensitive resin (A).

((C) Diluent)
The diluent (C) comprises at least one of a photopolymerizable monomer and an organic solvent. The photopolymerizable monomer is also referred to as a reactive diluent, and it is used to obtain a coating film having acid resistance, heat resistance, alkali resistance, etc. by further sufficient photocuring of the photosensitive resin (A). To do. As the reactive diluent, a compound having at least two double bonds in one molecule is preferably used. (A) An organic solvent which is a non-reactive diluent may be used in order to adjust the viscosity and drying property of the composition containing the photosensitive resin, but the organic solvent may not be used if it is not necessary. . In addition, when the photocurability of only the photosensitive resin (A) is sufficient, a photopolymerizable monomer may not be used.

  Typical examples of the photopolymerizable monomer (reactive diluent) include 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, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (Meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipe Taerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propion Examples include reactive diluents such as acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate.

  The above-mentioned 2-6 functional and other polyfunctional reactive diluents can be used in either a single product or a plurality of mixed systems. As for the addition amount of this reactive diluent, 2.0-40 mass parts is preferable with respect to 100 mass parts of (A) photosensitive resin. If the amount added is too small, sufficient photocuring cannot be obtained, and sufficient characteristics such as acid resistance of the cured coating film cannot be obtained. Adhesion to the surface is likely to occur, making it difficult to obtain the desired cured coating film. From the standpoint of photocurability, physical properties such as acid resistance and heat resistance of the cured coating, and prevention of adhesion of the artwork film to the substrate, the amount of reactive diluent added is (A) 100 parts by weight of the photosensitive resin. On the other hand, it is more preferably 4.0 to 30 parts by mass.

  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, and alicyclic carbonization such as cyclohexane and methylcyclohexane. Petroleum solvents such as hydrogen, 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 And acetates such as butyl carbitol acetate. When using an organic solvent, it is preferable that the usage-amount is 40-500 mass parts with respect to 100 mass parts of (A) photosensitive resin.

((D) Titanium oxide)
Titanium oxide particles having anatase and rutile crystal structure and whitening the coating film. From the viewpoint of whiteness, rutile type titanium oxide is preferable. Although the average particle diameter of particle | grains is not specifically limited, 0.01-1 micrometer may be sufficient. Further, the surface treatment agent for rutile-type titanium oxide particles is not limited. In the composition of the present invention, the whiteness of the coating film can be increased by setting the amount of (D) titanium oxide used to 10 parts by mass or more with respect to 100 parts by mass of (A) the photosensitive resin. From this viewpoint, the amount of (D) used is more preferably 40 parts by mass or more, and still more preferably 60 parts by mass or more with respect to 100 parts by mass of (A) the photosensitive resin. Also, the amount of (D) used exceeds (A) 100 parts by weight of the photosensitive resin, and even if it exceeds 120 parts by weight, the whiteness does not increase and there is an adverse effect in terms of strength, etc. The amount is preferably 120 parts by mass or less, and more preferably 100 parts by mass or less.

((E) Epoxy resin)
By including the specific epoxy resins of the general formulas (1) to (5) described above in the resin composition of the present invention, in the white photocurable thermosetting resin composition, UV irradiation, the white coating film due to the thermal history A cured resin film with little discoloration and low reflectance can be obtained.

As specific examples of the epoxy resins of the general formulas (1) to (5), the following are particularly preferable.
General formula (1): R1 and R2 are hydrogen atoms.
General formula (2): R1, R2, and R3 are hydrogen atoms.
General formula (3): R1, R2, R3, R4, R5, R6, R7 and R8 are hydrogen atoms.
General formula (4): R1, R2, R3, R4, R5 and R6 are hydrogen atoms. )
General formula (5): R1 and R4 are t-butyl groups, and R2 and R3 are hydrogen atoms.

Moreover, the following is especially preferable as a specific example of the epoxy resin of General formula (1)-(5).
General formula (1): “ADAMANTATE E-201” manufactured by Idemitsu Kosan Co., Ltd.
General formula (2): “ADAMANTATE X-E-202” manufactured by Idemitsu Kosan Co., Ltd.
General formula (3): “ADAMANTATE X-E-203” manufactured by Idemitsu Kosan Co., Ltd.
General formula (4): “ADAMANTATE X-E-401” manufactured by Idemitsu Kosan Co., Ltd.
General formula (5): “YDC-1312” manufactured by Tohto Kasei Co., Ltd.

  In the composition of the present invention, the amount of (E) epoxy resin used is preferably 10 to 50 parts by mass, and preferably 20 to 40 parts by mass with respect to 100 parts by mass of (A) photosensitive resin. Further preferred.

(Ingredients other than A to E)
In addition to the above components (A) to (E), the composition of the present invention may contain an acid anhydride or the like as a curing agent for an epoxy resin, if necessary.

Examples of the acid anhydride compound include aromatic acid anhydrides such as phthalic anhydride, trimellitic anhydride and pyromellitic anhydride, and cyclic aliphatic acid anhydrides such as tetrahydrophthalic anhydride and methyltetrahydrophthalic anhydride. . From the viewpoint of whiteness, hydrogenated cycloaliphatic acid anhydrides such as hexahydrophthalic anhydride and methylhexahydrophthalic anhydride are preferred.

  In addition to the above components (A) to (E), the composition of the present invention may contain various additives such as antifoaming agents, leveling agents, antioxidants and other additives for coatings as necessary. It can be included.

  The composition of the present invention may contain an epoxy compound other than the epoxy compounds (E) of the general formulas (1) to (5). As other epoxy compounds, typical epoxy-based thermosetting compounds include epoxy resins (including epoxy oligomers) having at least one epoxy group, preferably two or more epoxy groups in one molecule. Is preferable, but not limited thereto. For example, a bisphenol A type epoxy resin obtained by reacting bisphenol A and epichlorohydrin in the presence of an alkali, an epoxidized product of a resin obtained by condensation reaction of bisphenol A and formalin, Instead, those using brominated bisphenol A, novolak type epoxy resins obtained by reacting novolak resin with epichlorohydrin to glycidyl ether (phenol novolak type epoxy resin, o-cresol novolak type epoxy resin, p-tert-butylphenol novolak type, etc. ), Bisphenol F-type and bisphenol S-type epoxy resins obtained by reacting bisphenol F and bisphenol S with epichlorohydrin, cyclohexene oxide groups, tricyclode Such as cycloaliphatic epoxy resins having thiol oxide groups, cyclopentene oxide groups, diglycidyl phthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl-p-hydroxybenzoic acid, glycidyl dimer, etc. Glycidyl ester resins, tetraglycidyl diaminodiphenylmethane, glycidylamine resins such as triglycidyl-p-aminophenol, (propylene, polypropylene) glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane poly Glycidyl ether, resorcin diglycidyl ether, 1,6 hexanediol diglycidyl ether, , Propylene) glycol diglycidyl ether, sorbitol polyglycidyl ether, sorbitan polyglycidyl ether, glycidyl ether resins such as pentaerythritol polyglycidyl ether, tris (2,3-epoxypropyl) isocyanurate, triglycidyl tris (2-hydroxyethyl) ) Triglycidyl isocyanurate having a triazine ring such as isocyanurate, dicyclopentadiene type epoxy resin and the like.

  Although the usage-amount of components other than (A)-(E) component may be 0 mass part with respect to 100 mass parts of (A) photosensitive resin, 10-30 mass parts is preferable, and 15-25. Part by mass is more preferable.

(Production of composition and formation of solder resist)
The above components (A) to (E) and other components are mixed as necessary, and kneaded by a kneading means such as a three-roll, ball mill or sand mill, or a stirring means such as a super mixer or a planetary mixer, if necessary. Or it mixes and the photosensitive resin composition of this invention is obtained.

  The photosensitive resin composition of the present invention obtained as described above has a desired thickness, for example, 5 to 100 μm, on a printed wiring board having a circuit pattern formed by etching a copper foil of a copper-clad laminate, for example. It is applied with a thickness of. As a coating means, full-scale printing by the screen printing method is generally used at present, but any means may be used as long as it can be applied uniformly including this. For example, spray coaters, phone melt coaters, bar coaters, applicators, blade coaters, knife coaters, air knife coaters, curtain flow coaters, roll coaters, gravure coaters, offset printing, dip coaters, brush coating, and other ordinary methods can be used.

  After coating, pre-baking is performed in a hot air furnace or a far-infrared furnace as necessary, that is, temporary drying is performed to bring the surface of the coating film into a tack-free state. The prebaking temperature is preferably about 50 to 100 ° C.

Next, exposure by laser direct drawing using LDI (Laser Direct imaging) is performed. Alternatively, exposure with active energy rays is performed using a negative mask that prevents the passage of active energy rays. As the negative mask, a negative film is used when the active energy ray is ultraviolet light, a metal mask is used when it is an electron beam, and a lead mask is used when it is an X-ray, but it can be printed because a simple negative film can be used. In the production of wiring boards, ultraviolet rays are often used as active energy rays. The irradiation amount of ultraviolet rays is about 10 to 1000 mJ / cm ² .

  In the case of manufacturing a printed wiring board, for example, except for the soldering land of the circuit pattern, the light-transmitting pattern negative film is brought into close contact, and ultraviolet light is irradiated from above. The coating film is developed by removing the non-exposed areas corresponding to the lands with a dilute alkaline aqueous solution. This removal may be any of dissolution, swelling, peeling, etc. of the unexposed part. The dilute alkaline aqueous solution used at this time is generally 0.5 to 5% sodium carbonate aqueous solution, but other alkalis can also be used.

  Next, when a thermosetting compound is contained, for example, heating is performed for 20 to 80 minutes in a dryer such as a hot-air oven or a far-infrared furnace at 130 to 170 ° C. Thus, a solder resist film can be formed.

  In this way, a printed wiring board coated with a solder resist film is obtained, on which electronic components are connected, fixed and mounted by soldering by a jet soldering method or a reflow soldering method. A circuit unit is formed.

  In the present invention, the printed wiring board coated with the solder resist film before mounting the electronic component and the printed wiring board mounted with the electronic component mounted on the printed wiring board are included in the object.

  Next, the present invention will be specifically described based on the following examples and comparative examples, but the present invention is not limited to the following examples.

(Synthesis Example 1: Synthesis of Resin A-1)
After reacting radically polymerizable unsaturated monocarboxylic acid with all or part of the epoxy group of the alicyclic skeleton epoxy resin having two or more epoxy groups in the molecule, the resulting hydroxyl group is polybasic acid or polybasic acid anhydride A photosensitive resin obtained by reacting the product was synthesized. The specific manufacturing method is as follows.

Acrylic acid (270 parts by mass of epoxy resin (manufactured by Daicel Chemical Industries, Ltd., EHPE-3150) dissolved in 400 parts by mass of cellosolve acetate was added to acrylic acid (
(Unsaturated group-containing monocarboxylic acid) 110 parts by mass was added and reacted under heating and reflux conditions by a conventional method. This reaction product was reacted with 160 parts by mass of tetrahydrophthalic anhydride (polybasic acid anhydride) by a conventional method. A product (resin A-1) was obtained.

(Synthesis Example 2 Synthesis of Resin A-2)
As an epoxy resin, 210 parts by mass of cresol novolac type epoxy resin (manufactured by DIC, N-680) was added to diethylene glycol monoethyl ether acetate 120.
72 parts by mass of acrylic acid was added to the product dissolved in parts by mass, and reacted under a heating and refluxing condition by a conventional method. To this reaction product, 76 parts by mass of tetrahydrophthalic anhydride (polybasic acid anhydride) was reacted by a conventional method, The product (Resin A-2) was obtained.

Example 1
Each component was mixed with the following mass ratio, and the soldering resist composition was produced. Detailed component amounts are shown below.
(A) Photosensitive resin (Daicel Chemical Industries, Cyclomer P (ACA) Z-250) 100 parts by mass (B) Alkylphenone photopolymerization initiator (Ciba Specialty Chemicals, Irgacure 907) 5 parts by mass (C) Diluent (Aronix M-400, manufactured by Toa Gosei Co., Ltd.) 12.5 parts by mass (D) Rutile titanium oxide (R-680, manufactured by Ishihara Sangyo Co., Ltd.) 87.5 parts by mass (E) Epoxy resin (Idemitsu Kosan Co., Ltd., ADAMANTATE E-201) 25 parts by mass (other ingredients)
Defoamer (KS-66 manufactured by Shin-Etsu Silicone Co., Ltd.) 2.5 parts by mass Thixo (Aerosil R-974 manufactured by Nippon Aerosil Co., Ltd.) 2.5 parts by mass DICY-7 (manufactured by Japan Epoxy Resin Co., Ltd.) 1.25 parts by mass EDGAC (Daicel Chemical Industry Co., Ltd.) 50 parts by mass Barium sulfate B-34 (Sakai Chemical Industry Co., Ltd.) 12.5 parts by mass Melamine (Nissan Chemical Co., Ltd.) 2.5 parts by mass

(Example 2)
The alkylphenone photopolymerization initiator (Ciba Specialty Chemicals, Irgacure 907) was changed to 7.5 parts by mass of acylphosphine photopolymerization initiator (Ciba Specialty Chemicals, DAROCUR TPO). Is the same as in Example 1.

(Example 3)
The same as Example 1 except that the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE E-201) was changed to 25 parts by mass of the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE X-E-202).

Example 4
The same as Example 1 except that the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE E-201) was changed to 25 parts by mass of the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE X-E-203).

(Example 5)
The same as Example 1 except that the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE E-201) was changed to 25 parts by mass of the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE X-E-401).

(Example 6)
The same as Example 1 except that the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANATE E-201) was changed to 25 parts by mass of the epoxy resin (manufactured by Toto Kasei Co., Ltd., YDC-1312).

(Example 7)
The same as Example 1, except that the photosensitive resin (Daicel Chemical Industries, Cyclomer P (ACA) Z-250) was changed to 100 parts by mass of the resin (A-1) synthesized in Synthesis Example 1.

(Comparative Example 1)
The same as Example 1 except that the epoxy resin (manufactured by Idemitsu Kosan Co., Ltd., ADAMANTATE E-201) was changed to 25 parts by mass of the epoxy resin (manufactured by DIC, EPICLON 860).

(Comparative Example 2)
The same as Example 1 except that the photosensitive resin (Daicel Chemical Industries, Ltd., Cyclomer P (ACA) Z-250) was changed to 100 parts by mass of the resin (A-2) synthesized in Synthesis Example 2.

The blends of Examples 1 to 7 and Comparative Examples 1 and 2 were mixed and dispersed with three rolls to prepare a photosensitive resin composition. Table 1 shows the results of coating sensitivity, line remaining, discoloration, and reflectance of this composition.
The substrate manufacturing process at the time of evaluation is as follows.
Surface treatment: buffing DRY film thickness: 20-23 μm
Pre-drying: 70 ° C-20 minutes (25 minutes in BOX furnace)
Exposure: On resist: 400 mJ / cm ² (OMW HMW-680GW)
Development: 1% Na2CO3-30 ° C.-0.1 MPa-60 seconds Post cure: 150 ° C.-60 minutes (70 minutes in BOX furnace)
Discoloration evaluation: Heating at 260 ° C. for 5 minutes and visually evaluating the discoloration of the cured coating film Reflectivity evaluation: Posting the reflectance of 450 nm After irradiation: Measuring the reflectance of the cured film after UV irradiation (50 J) After heating: Measure the reflectance of the cured coating after heating at 170 ° C for 100 hours

  In Examples 1, 2, 3, 4, 5, 6, and 7, there is little discoloration after heat curing, and no decrease in reflectance after ultraviolet irradiation is observed. In Comparative Examples 1 and 2, the color change after heat curing is large. Moreover, in the comparative example 1, the fall of the reflectance after ultraviolet irradiation is seen. Further, the decrease in reflectance after heating is also observed in Examples 1, 2, 3, 4, 5, 6, and 7, but is significantly suppressed as compared with Comparative Examples 1 and 2.

Claims (3)

(A) a carboxyl group-containing photosensitive resin having no aromatic ring,
(B) a photopolymerization initiator,
(C) Diluent,
(D) Titanium oxide and (E) One or more epoxy compounds selected from epoxy compounds represented by the following general formulas (1), (2), (3), (4) and (5) A white light curable resin composition comprising:

(In the general formulas (1), (2), (3), (4) and (5), R1, R2, R3, R4, R5, R6, R7 and R8 are each independently a methyl group, a hydrogen atom, Or a t-butyl group.)   A solder resist composition for printed wiring boards, comprising the photosensitive resin composition according to claim 1.   A printed wiring board on which a solder resist made of a cured product of the composition according to claim 2 is formed.