JPH02123359A - Photosensitive resin composition and photosensitive element - Google Patents

Abstract

PURPOSE:To form a solder mask having high resolution, high heat resistance and high flexibility by using a specified photosensitive resin compsn. and developing with a flame retardant developer consisting primarily of 1,1,1-trichloroethane. CONSTITUTION:A specified photosensitive resin compsn. is constituted of an unsatd. compd. obtd. by allowing 0.01-0.5 equiv. isocyanate ethyl methacrylate to react with 1 equiv. of OH group of a bisphenol A type epoxy resin, an unsatd. compd. obtd. by allowing a novolak type epoxy resin to react with an unsatd. carboxylic acid in a range of 0.01-0.7 ratio of acid equiv./epoxy equiv., and a sensitizer and/or a sensitizing system which generates free radicals by the effect of active rays. Thus, formation of a thick film picture image has become possible, and a solder mask having high reliability of high resolution, high heat resistance and high blanking workability is formed using a developer consisting primarily of a flame retardant solvent such as 1,1,1- trichloroethane, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a photosensitive resin composition for forming a protective film used in printed wiring board manufacturing, metal precision processing, and the like.

(Conventional technology) Traditionally, solder masks have been used in the printed wiring board industry.

Photosensitive resin compositions having excellent properties that can be used as resists for chemical plating and the like are known.

The main purpose of a solder mask is to limit the area during soldering, prevent solder bridging, etc., prevent corrosion of bare copper conductors, and maintain electrical insulation between conductors over a long period of time. It is to be.

By the way, solder masks are usually made of epoxy resin,
Printed masks whose main component is a thermosetting resin such as aminoplast resin are used.

However, in recent years, as the wiring density of printed wiring boards has increased, the requirements for electrical insulation between conductors have also become more severe, and the solder masks used therein are also required to be thick and have excellent dimensional accuracy, which screen printing methods cannot meet. It's gone.

Therefore, we used a photographic method (a method in which an image is formed by imagewise exposure followed by development) to form a solder mask that is thick (desirably 25 μm thick on the conductor) and has excellent J-method accuracy and reliability. It is desired that a photosensitive resin composition that can be used as a photosensitive resin composition.

Further, the printed wiring board on which the solder mask has been formed is punched out to the final required size by a punching machine. Therefore, a photosensitive resin composition that can form a flexible solder mask that is resistant to impact during punching is desired.

By the way, conventionally, as a photosensitive resin composition for forming a solder mask, for example, (1) a photosensitive resin composition containing an acrylic polymer and a photopolymerizable monomer as main components (JP-A-53-56018
(2) A photosensitive resin composition with good heat resistance containing as main components a photosensitive epoxy resin having a chalcone group in its main chain and an epoxy resin curing agent ( JP-A No. 54-82073, JP-A No. 58-62636, etc.), (3) Thick film curing whose main components are novolac type epoxy acrylate-1 containing epoxy groups and a photopolymerization initiator. A possible photosensitive resin composition for forming a solder mask (Japanese Patent Application Laid-open No. 61-272, etc.) is known.

(Problem to be Solved by the Invention) However, depending on the photosensitive resin composition of (1) above, a large amount of acrylic polymer is used to impart film properties, so the heat resistance of the cured film may not be sufficient. Additionally, there was a problem in that cracks occurred in the hardened film during punching.

In addition, although the above photosensitive resin composition (2) with good heat resistance has excellent punching processability, the photodimerizable photosensitive resin composition has low sensitivity, so it is difficult to form a thick resist film. Furthermore, since it is necessary to use a flammable organic solvent such as cyclohexanone as a developer, it is not desirable from a safety standpoint.

Furthermore, although the photosensitive resin composition of (3) above has excellent heat resistance, it has the problem that cracks tend to occur in the cured film during punching, leading to a decrease in electrical insulation properties. .

The present invention has been made in view of the problems mentioned in section 1.1. 1. A photosensitive material that can be developed with a flame-retardant developer such as 11-lychloroethane, has excellent resolution and heat resistance, and can form a flexible and highly reliable solder mask that is resistant to impact during punching. The present invention aims to provide a resin composition and a photosensitive element using the same.

(Means for Solving the Problems) The present invention provides 0.01 to 0.0. An unsaturated compound (A) obtained by reacting 5 equivalents of isocyanatoethyl methacrylate, a novolac type epoxy resin, and an unsaturated carboxylic acid with an acid equivalent/epoxy equivalent ratio of 0.01 to 0.
．． Unsaturated compound (B) obtained by reacting in the range of 7
The present invention also relates to a photosensitive resin composition containing a sensitizer and/or a sensitizer system (C) that generates free radicals by actinic light, and a photosensitive element using the same.

The photosensitive resin composition of the present invention has an unsaturated finish obtained by reacting 0.01 to 0.5 equivalents of isocyanate ethyl methacrylate to 1 equivalent of hydroxyl group of bisphenol A type epoxy resin as an essential component. Things (A
).

Bisphenol A type epoxy resin can be obtained by a condensation reaction between bisphenol A and epichlorohydrin.

As the bisphenol A type epoxy resin, for example, Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd. (softening point 64°C, poquin equivalent 450-500, molecular weight about 900)
1. Epicote 1002 (softening point 78°C, epoxy equivalent 600-7001 molecular weight approximately 1060), Epicote 10
55 (softening point 93℃, epoxy equivalent 800-9001
molecular weight 1350), Epicote 1007 (softening point 12
8℃.

Epoxy equivalent: 1750-2200. molecular weight approximately 2900)
, Epicote 1009 (softening point 144°C.

Epoxy equivalent: 2400-3300. molecular weight approximately 3750)
, Epicote 1010 (softening point ~, Epoquine equivalent 30
00-5000. (The above softening point, -epoxy equivalent and molecular weight values are from Yuka Shell Epoxy Co., Ltd.'s resin curing agent Ebicure [
F], Epomate [F] (ls/87.6) shown). These bisphenol A type epoxy resins preferably have a degree of polymerization of less than 20 and are solid at room temperature.

Isocyanatoethyl methacrylate has the structure shown by the following formula and is commercially available from Showa Ropeia Co., Ltd. (trade name M
OI).

CH3 CH2=C-C0O-CH2-CH2-NCO isocyanatoethyl methacrylate is 0.01 to 1 equivalent of hydroxyl group of bisphenol A epoxy resin.
It is used in an amount of 0.5 equivalent.

Usage amount of isocyanate ethyl methacrylate-1 or C1
, (,) When the equivalent is less than 8, the physical properties of the cured film, such as heat resistance and solvent resistance, are insufficient.

On the other hand, if the amount of isocyanate ethyl methacrylate used exceeds 0.5 equivalent, flexibility will not be imparted to the cured film and cracks will occur during punching.

In addition, when the bisphenol A type epoxy resin and isocyanate ethyl methacrylate are reacted, the synthesis time can be shortened by using a reaction accelerator such as a tertiary amine or an organic tin compound.

Furthermore, it is necessary to use a polymerization inhibitor to prevent gelation.

Next, the photosensitive resin composition of the present invention is obtained by reacting a novolac type epoxy resin and an unsaturated carboxylic acid as essential components at an acid equivalent/epoxy equivalent ratio in the range of 0.01 to 0.7. Contains an unsaturated compound (B).

The novolak-type epoxy resin used in the present invention is produced by reacting aldehyde with orthocresol, phenol, halogenated phenol, etc. in the presence of an acid catalyst, and adding epichlorohydrin to the phenolic hydroxyl group of the novolak-type resin in the presence of an alkali. It is obtained by reacting and is commercially available.

Orthocresol novolac type epoxy resins include:
For example, Araldite ECN129 manufactured by Ciba Geigy.
9 (softening point 99°C, epoxy equivalent 230), ECN
1280 (softening point 80'C, epoxy 1230)
, ECN1273 (softening point 73°C, epoxy equivalent 23
0), manufactured by Nippon Kayaku Co., Ltd., EOCN104 (softening point 9
0~100℃, epoxy ff1225~245),
ECN123 (softening point 80-90℃, epoxy equivalent 2
15-235), ECN127 equivalent weight 215-235), EOCNlol (softening point 65
-69°c1 epoxy equivalent 205-225).

As the phenol novolak type epoxy resin, for example, Epikote 154 (epoxy equivalent: 176 to
181), manufactured by Dow Chemical Company, DEN431 (epoxy equivalent: 172-179), DEN438 (epoxy equivalent: 175-182), manufactured by Tobu Kasei Co., Ltd., YDPN-6
38 (epoxy equivalent 170-190), YDPN-6
01 (epoxy equivalent 180-220), YDPN-6
02 (epoxy equivalent: 180 to 220), and the like.

Examples of the halogenated phenol novolac type epoxy resin include BREN (epoxy equivalent: 270-300, bromine content: 35-37%, softening point: 80%, manufactured by Nippon Kayaku Co., Ltd.).
Examples include brominated phenol novolak type epoxy resins such as 90°C).

The molecular weight of the novolak epoxy resin is preferably 5,000 or less.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, β-furylacrylic acid, β-styrylacrylic acid, α
- Examples include cyanocinnamic acid and cinnamic acid.

In the present invention, the addition reaction between these novolac type epoxy resins and unsaturated carboxylic acids is carried out at an acid equivalent/epoxy equivalent ratio of 0.01 to 0. This is done by leaving 7+'; in the range of 7.

When the acid equivalent/epoxy equivalent ratio is less than 0.01, the photocured film is likely to swell during development treatment after image exposure.

Further, the acid equivalent/epoxy equivalent ratio is 0. If it exceeds 7, the cured film will not have flexibility and cracks will occur during punching.

The addition reaction product of a novolac type epoxy resin and an unsaturated carboxylic acid can be obtained, for example, by dissolving the above novolac type epoxy resin in an inert organic solvent such as methyl ethyl ketone, methyl cellosolve acetate, ethyl cellosolve acetate, or cyclohexanone, and adding l-diethylamino, Tertiary amines such as tri-n-butylamine and diethylcyclohexylamine, benzyltrimethylammonium chloride,
Quaternary ammonium salts such as benzyltriethylammonium chloride, and hydroquinone as a polymerization inhibitor.
It is obtained by stirring and reacting p-methoxyphenol or the like with the unsaturated carbonic acid at 70 to 110° C. in the equivalent ratio range described above.

The photosensitive resin composition of the present invention contains as an essential component (C) a sensitizer and/or a sensitizer system that generates free radicals by actinic light.

Examples of sensitizers include substituted or unsubstituted polynuclear quinones, such as 2-ethylanthraquinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2゜3-diphenylanthraquinone, diacetylbenzyl, etc. Ketoaldonyl compounds such as
α-ketaldonyl alcohols and ethers such as benzoin and Vivalon, α-hydrocarbon-substituted aromatic acyloins such as α-phenyl-benzoin, α,α-jethoxyacetophenone, etc., benzophenone, 4.4'-
Aromatic ketones such as bisdialkylaminobenzophenone, thioxanthone such as 2-methylthioxanthone, 2,4-diethylthioxanthone, 2-thalolthioxanthone, 2-isopropylthioxanthone, 2-ethylthioxanthone, 2-methyl-1-[ 4-(methylthio)phenyl'-2-morpholino-propanone-1 and the like are used, and they may be used alone or in combination.

Examples of the sensitizer system include 2,4.5-trianolimidazole dimer, 2-mercaptobenzoquinazole, leuco crystal violet], tris(4-diethylamino-2-methylphenyl)methane, etc. A combination of these is used.

In addition, sensitizer systems that do not have photoinitiation properties by themselves but have better photoinitiation performance as a whole when used in combination with the above substances (e.g., tertiary amines such as triethanolamine used in combination with benzophenone) , isoamyl dimethylaminobenzoate, N-methylethylketone, or bisethylaminobenzophenone used in combination with thioxanthone.

In the photosensitive resin composition of the present invention, an unsaturated compound (A
) 1 to 2 parts of unsaturated compound (B) per 100 parts by weight
00 parts by weight, and unsaturated compound (A) and unsaturated compound (
The sensitizer and/or sensitizer system (C) may be used in an IJ range of 1 to 30 parts by weight based on 100 parts by weight of the mixture of B), resolution, heat resistance and flexibility. This is preferable for forming a solder mask with excellent properties.

Furthermore, the photosensitive resin composition of the present invention may contain a photopolymerizable compound as another component.

Examples of such photopolymerizable compounds include trimethylolpropane triacrylate, pentaerythritol triacrylate-I, melimethylhexamethylene diisocyanate/2-hydrokine ethyl acrylate).
(1/2 molar ratio) reactant isocyanatoethyl methacrylate/water (2/1 molar ratio) reactant, and the like. Furthermore, photopolymerizable compounds disclosed in JP-A-53-56018 can also be used. These can be used within a range that does not impair the effects of the present invention, but unsaturated compounds (A) 10
The amount is preferably 30 parts by weight or less relative to 0 parts by weight.

Furthermore, the photosensitive resin composition of the present invention may contain a particulate filler.

Examples of fine particulate fillers include talc, silica, titanium oxide, clay, calcium carbonate, anhydrous acid, aluminum hydroxide, alumina, barium sulfate, antimony trioxide, magnesium carbonate, mica powder, aluminum silicate, magnesium silicate, etc. is used.

The particle size of the particulate filler is preferably 0.01 to 10 μm, more preferably 0.01 to 1.5 μm, from the viewpoint of preventing deterioration of resolution, adhesion of the cured film, and the like.

It is preferable that the particulate filler is uniformly dispersed in the photosensitive resin composition.

In order to increase the adhesive force between the filler and the photopolymerizable unsaturated compound, the surface of the filler is treated with a silane coupling agent having a functional group such as a hydroxyl group, an amino group, an epoxy group, or a vinyl group. It can also happen.

Examples of the silane coupling agent include γ-aminopropyltriethoxysilane, β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropino-rimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc. ρshu (gerareru)

Furthermore, the photosensitive resin composition of the present invention may contain other subsidiary components.

Secondary components include polymeric binders, thermal polymerization inhibitors, dyes, pigments, coatability improvers, antifoaming agents, flame retardants, adhesion improvers, latent hardeners for epoxy resins, etc. .

From the viewpoint of heat resistance, it is preferable to include a latent curing agent for epoxy resin.

The photosensitive resin composition of the present invention can be prepared by a dip coating method,
Coat directly onto the substrate to be processed and protected using conventional methods such as flow coating and screen printing to a thickness of 10 to 150 μm.
m photosensitive layers can be easily formed.

When coating, if necessary, the composition can be dissolved in a solvent.

Examples of the solvent include methyl ethyl ketone, methyl cellosolve acetate-1, and ethyl cellosolve acetate-1.
, nclohexanone, methyl cellosolve, propylene glycol monomethyl ether acetate-1-, and the like.

In addition, this 78 m can be placed on a film such as polyethylene terephthalate film or polyimide film, for example.
A photosensitive layer can also be formed by applying a photosensitive element by a knife coating method, a roll coating method, or the like, and then drying and laminating the photosensitive element on a substrate under heat and pressure using a hot roll. At this time, if the substrate has irregularities of 10 μm or more, such as a printed wiring board on which conductive wiring lines are formed, it is preferable to laminate the layers under a vacuum of 200 mm/g or less in order to prevent air entrainment. As an apparatus for this purpose, for example, a laminating apparatus described in Japanese Patent Publication No. 13341/1980 is used. In addition, when using a support film that is opaque to actinic light, it is necessary to peel off the support film at the time of exposure.

Exposure and development of the photosensitive layer thus formed are carried out by conventional methods. That is, using an ultra-high-pressure mercury lamp, a high-pressure mercury lamp, or the like as a light source, the layer of the photosensitive resin composition is exposed imagewise through a negative mask either directly or through a transparent film such as a polyethylene terephthalate film.

If a transparent film remains after exposure, it is peeled off and developed.

The type of developer used in the development process is not particularly limited as long as it does not damage the exposed areas and selectively elutes the unexposed areas.

As a developer, 1. 1. Flame-retardant cleaning agents containing 1-trichloroethane as a main component, such as 3-One EX (
(manufactured by Toagosei Kagaku Co., Ltd.) can be used.

The image-like protective film obtained by the above method has properties as a corrosion-resistant film for ordinary etching, plating, etc., but after development, it can be exposed to active light and heated at 80 to 200°.
By performing the heat treatment with C, properties such as adhesion, heat resistance, and solvent resistance can be improved, and a permanent protective film that improves the properties as a solder mask can be obtained. The order of exposure to active light and heat treatment may be either first.

The protective film obtained using the photosensitive resin composition of the present invention can be prepared using ht? It is sufficiently resistant to melting, and also resistant to acidic water/8 liquids or alkaline aqueous solutions.

Furthermore, since it has excellent heat resistance and mechanical properties, it can be used as a corrosion-resistant film for etching, plating, etc., and as a permanent protective film for solder masks, etc.

Furthermore, the film formed using the photosensitive resin composition of the present invention has excellent chemical and physical properties, and is therefore useful for use in interlayer insulation layers of multilayer printed wiring boards, photosensitive adhesives, paints, and plastics. It can also be used for reliefs, printing plate materials, metal precision processing materials, etc.

Furthermore, by using the photosensitive resin composition of the present invention, development can be achieved with a flame-retardant developer containing 1,1,1-trichloroethane as a main component, and resolution can be improved.

A solder mask with excellent heat resistance and flexibility can be formed, and a thick film solder mask can be formed by a photographic method.

(Example) Next, an example of the present invention will be described.

In addition, in the following, "part" shall mean 1 part by weight.

Example 1 (a) Production of unsaturated compound (A) As a bisphenol A epoxy resin, 75 parts of Epicote 1009 (softening point 144°C, molecular weight 3750) manufactured by Yuka Shell Epoxy Co., Ltd. was mixed with 75 parts of diethylene glycol monoethyl ether acetate. After heating and dissolving, add 10 parts of isocyanatoethyl methacrylate (Ebicor) 10
0.25 equivalents of isocyanate group per 1 equivalent of hydroxyl group of No.
I got it.

As a result of infrared analysis, it was confirmed that free isocyanate-1 groups in this unsaturated compound (A) had disappeared.

(b) Production of unsaturated compound (B) As an orthocresol novolac type epoxy resin, [
After heating and dissolving 92 parts of monolithic clay EOCN-1i-+4 (Ehoki/equivalent 230) in 60 parts of diethylene glycol monoethyl ether acetate, 4.3 parts of acrylic acid (acid equivalent/epoxy equivalent = 0.15), 0.03 part of benzyltrimethylammonium chloride and p
- Add a mixture of 0.03 parts of methoxyphenol dropwise over about 1 hour while maintaining the reaction temperature at 60°C, and then
After raising the temperature to 0°C, stirring was continued for about 15 hours to obtain an unsaturated compound (B) with an acid value of 1 or less.

(C) Preparation of photosensitive resin composition 190 parts of the unsaturated compound (A) obtained in (a) and (b)
25 of a mixture with 60 parts of the unsaturated compound (B) obtained in )
0 parts, 110 parts of 2-methyl-1-[4-(methylthio)phenyl-2-morpholinopropene, 4.4"
- 1 part of bisdiethylaminobenzophenone, 0.1 part of phthalocyanine green, 3 parts of 1-cyanoethyl-2-ethyl-4-methylimidazole and Modaflow.

Two parts were blended and mixed and dispersed using a roll mill to prepare a photosensitive resin composition (Later 71k).

(d) Formation of a cured film The solution of the photosensitive resin composition obtained in (C) was applied onto a copper-clad laminate, dried at room temperature for 20 minutes and at 80°C for 20 minutes, and dried to a thickness of 40 μm. A photosensitive layer was formed.

Next, through a negative mask, 600 mJ/cm was applied using a Phoenix 3000 type exposure machine manufactured by Oak Seisakusho Co., Ltd.
2 and exposed. After exposure, heat at 80°C for 5 minutes, leave at room temperature for 30 minutes, and heat with 75% of Three-One EX-DB (manufactured by Toa Kasei Kagaku Co., Ltd.).
% by weight) for 60 seconds at 20°C.

Next, I
After irradiating with J/cm2, heat treatment was performed at 150°C for 30 minutes to obtain a solder mask with excellent dimensional accuracy corresponding to a negative mask.

This solder mask has excellent cold and thermal shock resistance and has a mouth-shaped 7
2 using Lanox A-226 (manufactured by Tamura Scientific Research)
After applying heat treatment at 60°C for 10 seconds and cleaning with trichloride at 25°C for 10 minutes, MI L-
3TD-202E107D Condition B (-65℃ 30 minutes,
When a thermal shock test and a punching test were performed for 50 cycles at room temperature (for 5 minutes or less, 125°C for 30 minutes), no cracking or peeling of the coating was observed, and it was found that the product had excellent reliability.

Example 2 (a) Production of unsaturated compound (A) As bisphenol 12 epoxy resin, Epicoat 1010 manufactured by Yuka Shell Epoxy Co., Ltd. (molecular weight 5500)
After heating and dissolving 75 parts of diethylene glycol monoethyl ether acetate, isocyaner!・Processing 10 parts of ethyl methacrylate (0.25 equivalents of isocyanate group per 1 equivalent of hydroxyl group of Epicote 1009) and 0.2 parts of dibutyltin dilaurate, 60'
The mixture was reacted at C for 5 hours to obtain an unsaturated compound (A).

2.I. ``1a sum compound (, A) is the result of infrared component 1i,
It was confirmed that free isocyanate groups had disappeared.

(b) Production of unsaturated compound (B) As an orthocresol novolac type epoxy resin, EOCN-102 (epoxy equivalent weight 230) 9 manufactured by Nippon Kayaku Co., Ltd.
After heating and dissolving 2 parts in 60 parts of diethylene glycol monoethyl ether acetate, 1.4 parts of acrylic acid (acid equivalent/epoxy equivalent = 0.05), 0.01 part of benzyltrimethylammonium chloride and 0.01 part of p-methoxyphenol were added. While maintaining the reaction temperature at 60°C, the mixture was added dropwise over about 1 hour, and after the temperature was further raised to 80°C, stirring was continued for about 15 hours.
) was obtained.

('C) Preparation of photosensitive resin composition 190 parts of the unsaturated compound (A) obtained in (a), and (b)
) Mixture 26 with 70 parts of unsaturated compound (B) obtained in
0 parts, antimony trioxide (average particle size 0.15 μm) 6
parts, 10 parts of benzophenone, 70.5 parts of Michler's keto,
3 parts of 1-cyanoethyl-2-ethyl-4-methylimidazole and 0.04 part of Victoria Pure Blue were mixed and dispersed in a three-roll mill to prepare a solution of the photosensitive resin composition of the present invention.

Thereafter, a cured film having excellent heat resistance and punching workability was obtained in the same manner as in Example 1(d) above.

In addition, the above photosensitive resin composition was coated with a thickness of 0.8 mm and a UL9
Applied to both sides of a 4V-0 glass epoxy flame retardant base material (MCL-E-67 manufactured by Hitachi Chemical Co., Ltd.) with a thickness of 75 μm.
It was found that when a cured film was formed, flame retardancy of UL94V-1 was maintained.

Example 3 Micro Ace P was added to 250 parts of a mixture of 190 parts of the unsaturated compound (A) obtained in Example 2 (a) above and 60 parts of the unsaturated compound (B) obtained in Example 1 (b). -4 (talc manufactured by Nippon Talc, average particle size 1.5 μm) 2.5 parts, 2,4-diethylthioxanthone 4 parts, ethyl dimethylaminobenzoate 6 parts, Victoria Pure Flu 0.04 part, 2.4
The present invention A solution of the photosensitive resin composition was prepared.

Hereinafter, heat resistance was determined in the same manner as in Example 1(d) above.

A cured film with excellent punching workability was obtained.

(Effects of the Invention) The photosensitive resin composition of the present invention is capable of forming a thick film image by a photographic method, and also has the following characteristics: 1. It has the advantage that a highly reliable solder mask with excellent resolution, heat resistance, and punching workability can be formed using a developer containing a flame-retardant solvent such as 1-trichloroethane as a main component.

Claims (1)

[Claims] 1. An unsaturated compound (A) obtained by reacting 0.01 to 0.5 equivalents of isocyanate ethyl methacrylate to 1 equivalent of hydroxyl group of bisphenol A epoxy resin, novolac type epoxy An unsaturated compound (B) obtained by reacting a resin and an unsaturated carboxylic acid with an acid equivalent/epoxy equivalent ratio in the range of 0.01 to 0.7, a sensitizer that generates free radicals by actinic light, and ( or) a photosensitive resin composition containing a sensitizer system (C). 2. A photosensitive element obtained by applying the photosensitive resin composition according to claim 1 onto a film and drying it.