JP4989435B2 - Photosensitive resin and photosensitive resin composition - Google Patents

Description

  The present invention relates to a photosensitive resin and a photosensitive resin composition containing the photosensitive resin. More specifically, the present invention relates to a photosensitive resin composition suitable for a solder resist ink for printed wiring boards, which is soluble in a dilute alkali and has excellent sensitivity, reliability, and dryness to touch.

  In recent years, dilute alkali development type liquid solder photoresist inks are widely used as solder resist inks for printed wiring boards because of workability and environmental problems. For example, as shown in Patent Document 1, a resin composition containing a novolac type epoxy (meth) acrylate having a carboxy group in the side chain has been proposed and is now mainstream.

  In recent years, electronic devices have been reduced in size, weight, and performance, and the solder resist pattern has become fine due to these backgrounds. In order to cope with these, high sensitivity is required. However, the above technique is insufficient.

  Therefore, studies have been made to increase the photosensitivity with a novolac type epoxy (meth) acrylate which is a photosensitive resin. As this method, a method using a long-chain unsaturated monobasic acid in combination with (meth) acrylic acid, or a method using a monobasic acid having a polyfunctional unsaturated group in combination with (meth) acrylic acid (Patent Document 2). Etc. have been reported. However, by introducing a flexible structure in these technologies, stickiness after solvent drying of the resin (so-called finger dryness) is likely to occur, and problems such as sticking of a photomask used during pattern exposure occur, resulting in productivity. There is a problem that drops significantly. Furthermore, the latter has a problem that the stability of the photosensitive resin is remarkably deteriorated.

  A photosensitive resin (Patent Documents 3 and 4) obtained by reacting a novolac type epoxy (meth) acrylate with (glycidyl) methacrylate, and a novolac type epoxy (meth) acrylate with (glycidyl) methacrylate and a water-soluble monoepoxy. A photosensitive resin is also introduced (Patent Document 5). Although these also have high photosensitivity, the dryness to touch is insufficient, and in Patent Documents 3 and 4, the thermal stability is poor.

Japanese Patent Publication No. 1-54390 JP 11-021327 A Japanese Patent No. 2900137 Japanese Patent No. 2963069 JP 2001-264977 A

  Accordingly, an object of the present invention is to provide a photosensitive resin and a photosensitive resin composition having high sensitivity and sufficient touch-drying property on use, and sufficient reliability, and curing thereof. It is to provide a product (especially useful for solder resist ink).

As a result of earnest examination of the problems described above, the present inventors have
(1) A polybasic acid anhydride to a resin obtained by reacting a novolac-type epoxy resin (a), a compound (b) represented by the following general formula (I), and (meth) acrylic acid (c) Photosensitive resin (A) obtained by reacting (d) and further reacting with glycidyl (meth) acrylate (e),

（式中、Ｒは水素又はメチル基である）
（２）一般式（Ｉ）で表される化合物（ｂ）の割合が、ノボラック型エポキシ樹脂（ａ）のエポキシ基１．０モルに対して０．０５から０．５０モルであることを特徴とする（１）に記載の感光性樹脂（Ａ）、
（３）多塩基酸無水物（ｄ）の割合が、ノボラック型エポキシ樹脂（ａ）のエポキシ基１．０モルに対して０．４０から０．８５モルであることを特徴とする（１）または（２）に記載の感光性樹脂（Ａ）、
（４）グリシジル（メタ）アクリレート（ｅ）の割合が、ノボラック型エポキシ（ａ）のエポキシ基１．０モルに対して０．１モル以上であり、かつ固形分酸価が４０〜９０ｍｇＫＯＨ／ｇであることを特徴とする（１）〜（３）のいずれかに記載の感光性樹脂（Ａ）、
（５）（１）〜（４）のいずれかに記載の感光性樹脂（Ａ）、エポキシ樹脂（Ｂ）、反応性希釈剤（Ｃ）、光開始剤（Ｄ）を含む感光性樹脂組成物、
（６）ソルダーレジスト用感光性樹脂組成物である（５）に記載の感光性樹脂組成物、及び
（７）（５）または（６）に記載の感光性樹脂組成物を硬化させてなる硬化塗膜を開発することにより上記課題を解決した。

(Wherein R is hydrogen or a methyl group)
(2) The ratio of the compound (b) represented by the general formula (I) is 0.05 to 0.50 mol with respect to 1.0 mol of the epoxy group of the novolac type epoxy resin (a). The photosensitive resin (A) according to (1),
(3) The ratio of the polybasic acid anhydride (d) is 0.40 to 0.85 mol with respect to 1.0 mol of the epoxy group of the novolac type epoxy resin (a) (1) Or the photosensitive resin (A) according to (2),
(4) The ratio of glycidyl (meth) acrylate (e) is 0.1 mol or more with respect to 1.0 mol of the epoxy group of the novolak type epoxy (a), and the solid content acid value is 40 to 90 mgKOH / g. The photosensitive resin (A) according to any one of (1) to (3),
(5) A photosensitive resin composition comprising the photosensitive resin (A) according to any one of (1) to (4), an epoxy resin (B), a reactive diluent (C), and a photoinitiator (D). ,
(6) Curing obtained by curing the photosensitive resin composition according to (5), which is a photosensitive resin composition for solder resist, and (7), (5) or (6). The above problems have been solved by developing a coating film.

  According to the present invention, it is possible to provide a photosensitive resin or a photosensitive resin composition that is particularly useful for a solder resist and has high sensitivity and sufficient finger-drying dryness and reliability.

The present invention is described in detail below.
As the novolac type epoxy resin (a) used in the present invention, a publicly known one can be used. Examples include, but are not limited to, phenol novolac, cresol novolac, bisphenol novolac, phenol aralkyl, glycidyl ether of naphthol aralkyl, and the like. Moreover, you may use these 1 type or in mixture of 2 or more types.

  The compound (b) represented by the general formula (I) used in the present invention (hereinafter referred to as “compound (b)”) has a longer molecular chain and higher mobility of the photosensitive group than (meth) acrylic acid. High reactivity contributes to improved photosensitivity. In general, when the molecular chain is long and a flexible structure is included, the dryness of finger erosion tends to deteriorate, but the aromatic ring in the structure has the effect of suppressing the decrease in dryness of touch.

(Wherein R is hydrogen or a methyl group).

  The compound (b) can be synthesized by reacting phenylglycidyl ether (epoxy) and (meth) acrylic acid in equimolar amounts and then adding equimolar amounts of succinic anhydride. As the adduct of phenylglycidyl ether and acrylic acid, commercially available products (trade name: Aronix M5700, manufactured by Toagosei Co., Ltd.) can be used.

The proportion of compound (b) and (meth) acrylic acid (c) used is 0.98 in total of compound (b) and (meth) acrylic acid per 1.0 mol of epoxy group of epoxy resin (a). It is desirable that it is 1.02 mol. If the amount is less than 0.98 mol, the stability of the photosensitive resin may be deteriorated. If the amount exceeds 1.02 mol, there is a problem of odor derived from the remaining unreacted components.
The amount of the compound (b) used is desirably 0.05 to 0.50 mol with respect to 1.0 mol of the epoxy group of the epoxy resin (a). If it is less than 0.05 mol, it is difficult to sufficiently obtain the effects of the present invention. When the amount exceeds 0.50 mol, the effect of improving the photosensitivity corresponding to the amount used cannot be obtained, and there is a problem that the reaction time with the novolak type epoxy (a) becomes long because of relatively poor reactivity.

  A known method can be used for the reaction of the novolac type epoxy resin (a), the compound (b), and the (meth) acrylic acid (c). For example, the reaction can be performed at a reaction temperature of 70 to 140 ° C. In the reaction, a known esterification catalyst or a polymerization inhibitor can be used in combination. Esterification catalysts include amine catalysts such as triethylamine and benzyldimethylamine, imidazoles, triphenylphosphine, tributylphosphine, tri-o-toluylphosphine, tri-m-toluylphosphine, tri-p-toluylphosphine, tris ( Examples thereof include phosphorus catalysts such as p-methoxyphenyl) phosphine, metal catalysts such as naphthenic acid metal salts and octylic acid metal salts, imidazoles, imidazole silanes and aminosilanes. As polymerization inhibitors, hydroquinone, methylhydroquinone, trimethylhydroquinone, methoquinone, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3 -Dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, 2,6-di-t-butyl-4-methoxyphenol, phenothiazine, etc. Is mentioned. Blowing air or oxygen into the reaction system is also an effective means.

  The polybasic acid anhydride (d) is not particularly limited. For example, maleic anhydride, phthalic anhydride, succinic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride Etc. One or two or more of these may be used in combination. The addition reaction of polybasic acid anhydride (d) can also use a well-known method, for example, can be made to react at 70-130 degreeC.

  The usage-amount of a polybasic acid anhydride (d) is 0.4 to 0.85 mol with respect to 1.0 mol of epoxy groups of a novolak-type epoxy resin (a). If it is less than 0.4 mol, it is difficult to obtain sufficient solubility in a dilute alkali developer, and if it exceeds 0.85 mol, the water resistance of the cured product tends to deteriorate and PCT resistance tends to deteriorate. is there.

Glycidyl (meth) acrylate (e) reacts with the carboxyl group produced by the reaction of polybasic acid anhydride (d) to introduce a photosensitive group.
The amount of glycidyl (meth) acrylate (e) used is 0.1 mol or more with respect to 1.0 epoxy group of the novolac type epoxy resin (a), and the solid content acid value of the photosensitive resin (A) of the present invention is The amount is desirably in the range of 40 to 90 mgKOH / g. If the amount of glycidyl (meth) acrylate (e) used is less than 0.1 mol, it is difficult to sufficiently obtain the effects of the present invention. If the acid value is less than 40 mgKOH / g, sufficient alkali developability may not be obtained. If the acid value exceeds 90 mgKOH / g, the water resistance of the cured product tends to deteriorate and the PCT resistance tends to deteriorate. is there. The amount of glycidyl (meth) acrylate used can be easily determined from the solid content acid value.

  Concerning the photosensitive resin (A) of the present invention, it is possible to obtain a significant improvement in touch drying and photosensitivity against the expectation from the case where only the compound (b) or glycidyl (meth) acrylate (e) is used. I can do it.

  According to another aspect of the present invention, there is provided a photosensitive resin composition comprising the photosensitive resin (A), an epoxy resin (B), a reactive diluent (C), and a photoinitiator (D). . Furthermore, the present invention provides the photosensitive resin composition for use in a cured coating film or a solder resist obtained by curing the photosensitive resin composition.

An epoxy resin (B) improves the characteristic of a cured coating film by thermosetting with the carboxyl group in photosensitive resin (A). As epoxy resin (B), in addition to novolac type epoxy (a), bisphenol A type epoxy, bisphenol F type epoxy, bisphenol S type epoxy, bisphenol AF type epoxy, biphenyl type epoxy, bisphenol fluorene type epoxy, triglycidyl cyanurate, An alicyclic epoxy (for example, EHPE3150 or Celoxide 2021P manufactured by Daicel Chemical Industries, Ltd.) and the like are exemplified, but not particularly limited. Epoxy resins can be used alone or in combination of two or more. The usage-amount of an epoxy resin (B) is 5-100 mass parts with respect to 100 mass parts of photosensitive resin (A).

  The reactive diluent (C) is used for the purpose of adjusting the viscosity of the photosensitive resin composition of the present invention and for the purpose of reacting with the photosensitive resin (A) and curing. Although not particularly limited, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, isobornyl (Meth) acrylate, glycidyl (meth) acrylate, tricyclodecynyl (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, propylene glycol (meth) acrylate. Dipropylene glycol (meth) acrylate, tripropylene glycol (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate And (meth) acrylic monomers such as tris (hydroxyethyl) isocyanurate tri (meth) acrylate, and the like, and one or more of these can be used. The amount of the reactive diluent (C) is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the photosensitive resin (A).

  The photoinitiator (D) can be added to the photosensitive resin composition of the present invention to be photocured by ultraviolet irradiation or the like. Although it does not specifically limit as a photoinitiator which can be utilized, For example, benzoin, such as benzoin, benzoin methyl ether, benzoin ethyl ether, and its alkyl ethers; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1 Acetophenones such as dichloroacetophenone and 4- (1-t-butyldioxy-1-methylethyl) acetophenone; anthraquinones such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone and 1-chloroanthraquinone; Thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone and 2-chlorothioxanthone; Ketals such as acetophenone dimethyl ketal and benzyldimethyl ketal; Ben Benzophenones such as phenone, 4- (1-t-butyldioxy-1-methylethyl) benzophenone, 3,3 ′, 4,4′-tetrakis (t-butyldioxycarbonyl) benzophenone; 2-methyl-1- [ 4- (methylthio) phenyl] -2-morpholino-propan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1; acylphosphine oxides and xanthones. It is preferable to mix | blend the compounding quantity of a photoinitiator (D) with 0.5-30 mass parts with respect to 100 mass parts of solid content of the photosensitive resin (A) of this invention.

  Furthermore, the composition of the present invention can contain known solvents, fillers such as barium sulfate and talc, pigments, pigment dispersants, antifoaming agents, coupling agents, leveling agents, and the like as necessary.

  The photosensitive resin composition of the present invention can be obtained by mixing and dispersing using a ball mill, a bead mill, a three roll mill, a homogenizer or the like. The photosensitive resin composition is applied to a copper-clad substrate by screen printing, curtain coater, spray coater, etc., the coating film is dried with a solvent, the composition is exposed and developed, and post-baked to improve various physical properties. And cured sufficiently to obtain a cured coating film.

  The present invention will be specifically described below with reference to examples and comparative examples. All parts and percentages are based on mass unless otherwise specified.

Synthesis Example of Compound b Into a reaction apparatus in which a stirrer, a thermometer, an air introduction tube, and a reflux condenser were set in a four-necked flask, 222 parts of acrylate of phenylglycidyl ether (Aronix M5700, manufactured by Toagosei Co., Ltd.) (1. 0 mol), 0.2 parts of methoquinone, 0.5 parts of triethylamine, 138 parts of diethylene glycol monoethyl ether acetate, heated to 100 ° C. while blowing air, and 100.0 parts (1.0 mol) of succinic anhydride were added. The reaction was carried out at 90 ° C. for 20 hours. The disappearance of peaks derived from acid anhydrides of 1850 cm ⁻¹ and 1770 cm ⁻¹ was confirmed by an infrared spectrometer, and the target compound (b) represented by the general formula (I) (wherein R is hydrogen, The molecular weight was confirmed to be 322) (FIG. 1). Hereinafter, this composition is referred to as Compound B.

Synthesis example 1
In a reaction apparatus in which a stirrer, a thermometer, an air introduction tube, and a reflux condenser are set in a four-necked flask, 212 parts of epiclone N680 (Cresol novolac type epoxy, epoxy equivalent 212, manufactured by Dainippon Ink & Chemicals, Inc.) (1. 01.3), 191.3 parts of diethylene glycol monoethyl ether acetate, 69.0 parts of compound B (containing 48.3 parts (0.15 mole) of compound (b)), 61.2 parts (0.85 mole) of acrylic acid Then, 0.2 part of methylhydroquinone and 0.2 part of triphenylphosphine were charged, heated to 130 ° C. while blowing air, and reacted for about 10 hours to obtain a reaction product having an acid value of 0.5 mgKOH / g. Next, the temperature was lowered to 90 ° C., 91.2 parts (0.6 mol) of tetrahydrophthalic anhydride was added, and the mixture was reacted at 90 ° C. for 6 hours. Thereafter, 21.3 parts (0.15 mol) of glycidyl methacrylate was added and reacted at 90 ° C. for an additional 6 hours. Diethylene glycol monoethyl ether acetate was added so that the resin solid content was 60%, and the solid content acid value was 58.2 mgKOH / g. A photosensitive resin (A-1) was obtained.

Synthesis example 2
Synthesis Example 1 except that Compound B was changed to 23.0 parts by mass (containing 16.1 parts by mass (0.05 mol) of Compound (b)) and acrylic acid was changed to 68.4 parts by mass (0.95 mol). In the same manner as above, a photosensitive resin (A-2) having a solid content acid value of 61.7 mgKOH / g was obtained.

Synthesis example 3
Reaction was performed in the same manner as in Synthesis Example 1 except that 230.0 parts by mass of Compound B (containing 161 parts by mass (0.5 mol) of Compound (b)) and 36 parts by mass (0.5 mol) of acrylic acid were changed. The photosensitive resin (A-3) having a solid content acid value of 48.4 mgKOH / g was obtained.

Synthesis example 4
The reaction was conducted in the same manner as in Synthesis Example 1 except that tetrahydrophthalic anhydride was changed to 60.8 parts (0.4 mol) and glycidyl methacrylate was changed to 14.2 parts (0.1 mol). 5 g KOH / g photosensitive resin (A-4) was obtained.

Synthesis example 5
The reaction was conducted in the same manner as in Synthesis Example 1 except that tetrahydrophthalic anhydride was changed to 129.2 parts (0.85 mol) to obtain a photosensitive resin (A-5) having a solid content acid value of 83.2 mgKOH / g. It was.

Synthesis Example 6
A reaction was performed in the same manner as in Synthesis Example 1 except that glycidyl methacrylate was changed to 14.2 parts (0.1 mol) to obtain a photosensitive resin (A-6) having a solid content acid value of 65.7 mgKOH / g.

Synthesis example 7
Glycidyl methacrylate 38.34. The reaction was conducted in the same manner as in Synthesis Example 1 except that the amount was changed to 0.17 mol (0.27 mol) to obtain a photosensitive resin (A-7) having a solid content acid value of 41.1 mgKOH / g.

(Comparative Synthesis Example 1)
The synthesis was performed in the same manner as in Synthesis Example 1 except that the compound (b) represented by the general formula (I) and glycidyl methacrylate were not used and the acrylic acid was changed to 72.0 parts by weight (1.0 mol). A photosensitive resin (B-1) having an acid value of 89.7 mgKOH / g was obtained.

(Comparative Synthesis Example 2)
The synthesis was performed in the same manner as in Synthesis Example 1 except that the compound (b) represented by the general formula (I) was not used and the acrylic acid was changed to 72.0 parts by weight (1.0 mol). A photosensitive resin (B-2) of .6 mgKOH / g was obtained.

(Comparative Synthesis Example 3)
Synthesis was performed in the same manner as in Synthesis Example 1 except that glycidyl methacrylate was not used, to obtain a photosensitive resin (B-3) having a solid content acid value of 63.7 mgKOH / g.

(Comparative Synthesis Example 4)
The succinic anhydride adduct of 2-hydroxyethyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name Light acrylate HOA-MS, molecular weight 281) instead of compound (b) was changed to 42.5 parts (0.15 mol). Except for this, synthesis was carried out in the same manner as in Synthesis Example 1 to obtain a photosensitive resin (B-4) having a solid content acid value of 60.3 mgKOH / g.

(Examples 1-7, Comparative Examples 1-4)
The composition shown in the recipe of Table 1 was prepared with three rolls. Next, this was coated on the copper-clad laminate with the circuit prepared by screen printing to a dry film thickness of 20.0 μm, put in a drier at 80 ° C. for 20 minutes, and solvent-dried. (Hereinafter referred to as a pre-dried coating film). Next, it exposed with the exposure amount of 200 mJ / cm < ² > using the ultrahigh pressure mercury lamp through the pattern mask. Next, it was developed for 60 seconds with a spray developing device (developer: 1% aqueous sodium carbonate solution, liquid temperature 30 ° C.), rinsed with pure water for 30 seconds, and dried. Next, it was placed in a dryer at 150 ° C. for 30 minutes and post-baked to obtain a cured coating film. The following items were evaluated for the obtained cured coating film and pre-dried coating film. The results are shown in Table 2.

Sensitivity Step tablet NO.2 (21 steps manufactured by Kodak Co., Ltd.) is brought into close contact with the pre-dried coating film and exposed at an exposure amount of 200 mJ / cm ^2. ) For 60 seconds, rinsed with pure water for 30 seconds, and the number of remaining steps of the dried coating film was measured.

Dryness to touch The ease of peeling when peeling the step tablet during the sensitivity measurement was evaluated.
○: There is no sticking.
Δ: Sticking is observed when peeling a little.
X: It sticks very much.

Drying control range The drying time of the pre-dried coating film was changed to 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, and 80 minutes, and the spray developing device (developer: 1% sodium carbonate aqueous solution, liquid temperature) The remaining condition of the coating film was visually evaluated when developed at 30 ° C. for 60 seconds.
○: The coating film is completely removed.
Δ: A part of the coating film remains.
X: A coating film remains completely.

Chemical resistance The test piece was immersed in a 2% aqueous sodium hydroxide solution at 40 ° C. or a 10% aqueous hydrochloric acid solution at 40 ° C. and methylene chloride at room temperature for 30 minutes to confirm the presence or absence of erosion.
○: No change in appearance.
Δ: Some erosion is observed.
X: Erosion is observed.

Adhesiveness The cross-cut test according to JIS K5400 was performed on the cured coating film, and the peeling state of 100 cross-cuts was visually evaluated.
○: No peeling at all.
Δ: Partial peeling (10% or less of the whole) is observed.
X: Detachment is recognized.

Pressure Cooker (PCT) Test The cured coating film was stored at 121 ° C. under 2 atm and saturated steam for 50 hours and 100 hours, and the state of the coating film after storage was visually evaluated.
○: No swelling or peeling at all.
Δ: Slightly swollen or peeled.
X: Swelling or peeling is recognized.

Gold plating resistance Pre-treatment of the hardened coating film, soaking in acidic degreasing solution at 30 ° C → immersion water washing → soft etching treatment → soaking water washing → providing catalyst (soaking in 30 ° C nickel plating catalyst solution for 7 minutes) → immersion water washing process I did it. Next, as an electroless nickel process, it is immersed in a nickel plating solution (85 ° C., pH = 4.6) for 20 minutes, acid-immersed for 1 minute (10 vol% sulfuric acid aqueous solution at room temperature), then immersed in water and washed, and finally an electroless gold plating process. As follows: Immerse in a gold plating solution (95 ° C., pH = 6, 3 vol% potassium gold cyanide aqueous solution) for 10 minutes → Immerse water wash → Immerse water wash with 60 ° C. hot water → Wash well, then dry well and dry . The coating film after this treatment was evaluated by visual evaluation of the coating film state and a peeling test using a cellophane tape.
A: No change in appearance and no peeling at all.
○: No change in appearance but slight peeling.
Δ: Appearance changes and slight peeling is observed.
X: Appearance change. Peeling is also observed.

Solder heat resistance The cured coating film is floated three times for 10 seconds in a 260 ° C solder bath according to JIS C6481, and the appearance of the coating film such as swelling or peeling of the coating film after removal is observed. evaluated.
A: No change in appearance.
○: slight change in appearance
X: Appearance changed.

It is a figure which shows the chart by the infrared spectrometer of the compound (b) synthesize | combined in the synthesis example 1. FIG.

Claims (7)

A polybasic acid anhydride (d) is added to the resin obtained by reacting the novolak-type epoxy resin (a), the compound (b) represented by the following general formula (I), and (meth) acrylic acid (c). Photosensitive resin (A) obtained by further reacting glycidyl (meth) acrylate (e).

(Wherein R is hydrogen or a methyl group)   The proportion of the compound (b) represented by the general formula (I) is 0.05 to 0.50 mol with respect to 1.0 mol of the epoxy group of the novolac type epoxy resin (a). Item 2. The photosensitive resin (A) according to item 1.   The ratio of the polybasic acid anhydride (d) is 0.40 to 0.85 mol with respect to 1.0 mol of the epoxy group of the novolak-type epoxy resin (a). The photosensitive resin (A) of description.   The ratio of glycidyl (meth) acrylate (e) is 0.1 mol or more with respect to 1.0 mol of the epoxy group of the novolak type epoxy (a), and the solid content acid value is 40 to 90 mgKOH / g. The photosensitive resin (A) as described in any one of Claims 1-3 characterized by these.   The photosensitive resin composition containing the photosensitive resin (A) as described in any one of Claims 1-4, an epoxy resin (B), a reactive diluent (C), and a photoinitiator (D).   The photosensitive resin composition according to claim 5, which is a photosensitive resin composition for a solder resist.   A cured coating film obtained by curing the photosensitive resin composition according to claim 5.

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