JPH03289656A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To make improvement in solubility in a solvent and the stability of the base polymer itself by using the base polymer obtd. by bringing acrylic acid into reaction with a copolymer of respectively specific compds. and further bringing a polybasic acid anhydride into reaction. CONSTITUTION:The base polymer which is obtd. by bringing the acrylic acid into reaction at 0.8 to 1.2mol per 1 epoxy equiv. of the copolymer with the copolymer of the compd. expressed by formula I and the compd. expressed by formula II and further, by bringing the polybasic acid anhydride into reaction and has 20000 to 70000 weight average mol. wt., 35 to 130 deg.C softening point and 50 tp 150 acid value, the diluent and the sensitizer are incorporated into this compsn. In the formulas I, II, R1 denotes a hydrogen atom or methyl group; R2 denotes 1 to 6C aliphat. hydrocarbon group; R3 denotes 1 to 12C aliphat. hydrocarbon group or arom. hydrocarbon group. The photosetting property, heat resistance, chemical resistance, flexibility, adhesive property, coated film hardness, electrical characteristics, etc., are improved in this way. This compsn. is usable as a one-part type photosolder resister which associates no problems in safety and solvent.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a photosensitive resin composition, and more particularly, it has an ultraviolet curable and solder heat resistant composition that can form an image by exposure to ultraviolet light and development with a dilute aqueous alkaline solution after forming a film. The present invention relates to a photosensitive resin composition useful as a liquid photo solder resist with excellent properties and the like.

[Conventional technology]

It is common practice to use printed wiring boards to compactly incorporate electronic components. This printed wiring board is made by etching copper foil pasted onto a laminated board according to the circuit wiring, and electronic components are placed in predetermined locations and soldered.

Solder resist is used in the pre-process of soldering electrical components to such printed wiring boards, and is a film formed on the entire surface of the circuit conductor except for the parts to be soldered. Such a film functions as an insulating film that prevents solder from adhering to unnecessary parts during soldering, and also prevents circuit conductors from being directly exposed to air and being corroded by oxidation and humidity. It functions as a protective film that protects the skin, and is indispensable.

Conventionally, such solder resists have been formed by screen printing on a substrate and curing with ultraviolet rays or heat. However, in order to achieve higher density printed circuit boards,
They are becoming increasingly finer, more numerous, and integrated into one board, and are becoming more sophisticated at an alarming pace. At the same time, the mounting method has also gradually shifted to surface mount technology (SMT). Demand for high resolution, high precision, and high reliability for solder resists has increased as SMT becomes finer. Regardless of whether it is a consumer-use board or an industrial board, the screen printing method has changed to a liquid type that has excellent positional accuracy and coverage of conductor edges. A photoresist method has been proposed. For example, JP-A-50-144431 and JP-A-51-40451 disclose ultraviolet curable solder resist compositions comprising epoxy acrylate, a sensitizer, an epoxy compound, an epoxy curing agent, and the like. The unexposed portions of these solder resists were removed using an organic solvent and developed. However, this removal (development) of unexposed areas using an organic solvent is problematic because it involves the use of a large amount of organic solvent, which poses risks such as environmental pollution and fire.

In particular, the problem of environmental pollution has recently been greatly amplified due to its effects on the human body, and the reality is that we are struggling to find countermeasures.

To solve this problem, an alkali-developable photo solder resist that can be developed with a dilute alkaline aqueous solution has been proposed.

As this type of alkali-developable photosolder resist material, JP-A-56-40329 and JP-A-57-4
5785% discloses a material whose base polymer is a reaction product obtained by reacting an epoxy resin such as bisphenol A type epoxy resin with an unsaturated monocarboxylic acid and further adding a polybasic acid anhydride. Also, JP-A-6
Japanese Patent No. 1-243869 discloses a liquid solder resist composition that is developable with a dilute alkaline aqueous solution and uses a novolac type epoxy resin instead of the bisphenol type epoxy resin.

However, these materials have excellent photocurability, heat resistance, chemical resistance (methylene chloride resistance, hydrochloric acid resistance, etc.), flexibility, adhesion, electrical properties, etc., which are the basic properties required for liquid photo solder resists. In addition, although the hardness of the coating after drying is high and the dry coating does not show stickiness, it is satisfactory, but it is a two-component type because the stability with liquid is poor.
The drawback is that storage after mixing is difficult.

In addition, for those using copolymers as the base polymer, JP-A-63-11930 and JP-A-63-205649
A composition using a half ester of a copolymer of styrene and maleic anhydride is disclosed in the publication. but,
Since both compositions contain epoxy resins such as bisphenol A type and novolac type,
Similarly, there are problems with the stability of the composition. Also, JP-A-62-
No. 285903, JP-A-63-72710 and JP-A-63-97601 disclose modified maleic anhydride copolymers derived from copolymers of maleic anhydride and unsaturated hydrocarbon compounds such as isobutylene. However, since the copolymer before modification is difficult to dissolve in general-purpose solvents, expensive imide-based solvents must be used, and as a result, the copolymer after modification is difficult to dissolve in general-purpose solvents. If the solvent remains in the polymer, the properties as a solder resist will be adversely affected. Furthermore, JP-A-63-976
Since the base polymer described in Publication No. 01 contains a large amount of imide rings, it has drawbacks such as poor solubility in solvents and poor stability of the base polymer itself.

[Problem to be solved by the invention]

The present invention uses a reaction product obtained from a specific epoxy group-containing copolymer as a base polymer to solve stability and solvent problems, and also to improve photocurability and heat resistance, which are the basic properties of liquid photoresists. The present invention provides a photosensitive resin composition useful as a one-component liquid photoresist that can be imitated with a dilute alkaline aqueous solution and has excellent properties such as hardness, chemical resistance, flexibility, adhesion, coating hardness, and electrical properties. be.

[Means to solve the problem]

As a result of intensive research for the purpose of solving the above-mentioned defects in the base polymer serving as the base material of the above-mentioned photosensitive resin composition, the present inventor found that the base polymer has the general formula (I) 1 [I] CH2=C-C00R2 (In the formula, R1 is a hydrogen atom or a methyl group, and R2 has 1 to 1 carbon atoms.
6 aliphatic hydrocarbon groups) and the general formula [■] (wherein R1 has the same meaning as above, and R3 has 1 to 1 carbon atoms)
A base polymer obtained by reacting a copolymer with a compound represented by 12 aliphatic hydrocarbon groups or aromatic carbon 1 arsenic group) with acrylic acid, and further reacting with a polybasic acid anhydride. However, they found a solution to the above problem and completed the present invention.

In the present invention, the acrylic acid to be reacted with the copolymer of formula (1) and formula [II] is reacted with 0.8 to 1.2 mol per 1 epoxy equivalent of the copolymer, and then Weight average molecular weight 2 obtained by reacting acid anhydride
It is a base polymer having an acid value of 0.000 to 70.000, a softening point of 35 to 130°C, and an acid value of 50 to 150.

The present invention is a photosensitive resin composition containing a diluent and a sensitizer in this base polymer.

The raw material copolymers of the base polymer used in the composition of the present invention are a compound represented by the above-mentioned formula [I], that is, an acrylic ester and/or a methacrylic ester, and a compound represented by the general formula [■], that is, each It is obtained by copolymerizing an acrylic ester and/or a methacrylic ester having an epoxy group at the end by a conventional method such as a solution polymerization method.

Here, the molar ratio of the compound of formula [I] to the compound of general formula [II] is preferably 40:60 to 80:20.

Note that if the amount of the compound of formula (II) is too small and the molar ratio is greater than 80:20, the amount of acrylic acid and further polybasic acid anhydride added to the copolymer will be reduced. , UV curability and developability with a dilute alkali aqueous solution will deteriorate, and conversely, if the amount of the compound of general formula [I[] is too large and the molar ratio is less than 40:60, the softening point will become too low. Tend.

Specific examples of compounds of general formula [■] include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl of acrylic acid or methacrylate;
Mention may be made of hexyl or isohexyl esters.

Further, specific examples of the compound represented by formula [11] include glycidyl (meth)acrylate.

In order to make the base polymer of the present invention from the epoxy group-containing copolymer obtained as described above, 0.8 to 1.2
After reacting a mole of acrylic acid, a polybasic acid anhydride is further reacted. In this case, it is preferable to react the polybasic acid anhydride so that the acid value of the reaction product is 50 to 150.

There are no particular restrictions on the polybasic acid anhydride, but examples include hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, and 3-ethyl anhydride. Hexahydrophthalic anhydride, 4-ethylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, 3-ethyltetrahydrophthalic anhydride , 4-ethyltetrahydrophthalic anhydride and the like are preferred.

The base polymer used in the present invention obtained as described above has a weight average molecular weight of 20.000 to 70,000, a softening point of 35 to 130°C, and an acid value of 50 to 150.

In addition, if the weight average molecular weight is too low, heat resistance will deteriorate,
If it is too high, solubility in the diluent and workability may deteriorate. In addition, if the softening point is too low, the composition of the present invention will remain sticky after being applied and dried, which may cause the composition to adhere to the negative film during exposure or cause uneven gloss on the surface of the cured film. On the other hand, if it is too high, the ultraviolet curability may deteriorate. Furthermore, if the acid value is too low, the removability of the film with a dilute aqueous alkaline solution will be poor, while if it is too high, the electrical properties and humidifying properties of the cured film will tend to be poor.

The photosensitive resin composition of the present invention contains a diluent and a sensitizer in the base polymer as described above.

The diluent used in the composition of the present invention has a boiling point (under normal pressure) of 1
00°C or higher and an unsaturated compound having at least two or more acryloyl groups or methacryloyl groups,
Representative substances include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, glycerin triacrylate, glycerin trimethacrylate, propylene diacrylate,
Propylene dimethacrylate, 1,2.4-butanetriol triacrylate, 1,2.4-butanetriol trimethacrylate, 1,4-benzenediol diacrylate, 1,4-benzenedimethacrylate, polyethylene glycol with a molecular weight of 200 to 500 bisacrylates and bismethacrylates, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, etc., melamine acrylate, epoxy acrylate, urethane acrylate,
Oligomers such as polyester acrylate, methylenebisacrylamide, methylenebismethacrylamide, diethylenetriaminetriacrylamidebis(methacrylamidopropoxy)ethane, diethylenetriaminetrimethacrylamidobis(methacrylamidopropoxy)ethane, bismethacrylamidoethylmethacrylate-N-[(β- Hydroxyethyloxy)ethyl coacrylamide, triacrylic isocyanate, trimethacrylic isocyanate, etc. In addition, in order to improve the coating properties of the composition of the present invention, ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, Ethylene glycol dialkyl ethers, diethylene glycol dialkyl ethers,
ethylene glycol monoalkyl ether acetates,
It can be used by mixing with organic solvents such as diethylene glycol monoalkyl acetates, cyclohexanone, tetrahydronaphthalene, and petroleum naphtha.

The sensitizer used in the composition of the present invention is not particularly limited, but
Among them, 2-methyl[4-(methylthio)phenyl]-2
-Morpholino-1-propane or/and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 as a main component, and 1 of other sensitizers.
Particularly excellent ultraviolet curability can be obtained by using one type or a combination of two types. Sensitizers used in the above combination include p-phenylbenzophenone, benzyl dimethyl ketal, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 4,4'- Examples include diethylaminobenzophenone and p-dimethylaminobenzoic acid ethyl ester.

The photosensitive resin composition of the present invention consists of the base polymer (a), diluent (b), and sensitizer (c) as described above, and the blending ratio thereof is 30 to 70 parts by weight of component (a). ,
(b) component 30 to 70 parts by weight, and (c) component 1 to 10
The range of parts by weight is preferable, and if necessary, various additives such as extender pigments such as silica, talc, alumina, calcium carbonate, clay, and Aerosil, coloring pigments such as chrome phthalo yellow and cyanine green, silicones, and fluorine-based Antifoaming agents, leveling agents, antioxidants, etc. can be added. Note that an epoxy resin or a phenol resin may be used in combination as a thermosetting component for the purpose of improving the heat resistance of the cured film, but in this case, it is necessary to pay attention to the stability of the resulting composition.

The photosensitive resin composition of the present invention described above is coated on a substrate to a desired thickness, and then heated at 60 to 80°C for 15 to 60 minutes to volatilize the organic solvent. The pattern is placed in contact with the coating film of the substrate, and the desired pattern is selectively exposed to ultraviolet light. This causes the composition in the exposed areas of the coating to form alternating bonds and become insoluble. The coating is then developed by removing the unexposed areas with a dilute aqueous alkaline solution. The dilute alkali aqueous solution used in this S is generally a 0.5 to 5% by weight sodium carbonate solution, but of course other alkalis can also be used. The pattern thus obtained is later exposed to ultraviolet rays or
React by adding heat at 200℃ or far infrared rays (secondary curing)
It is desirable to

〔Example〕

Examples of the production of the reaction product used in the present invention and Examples of the present invention are shown below, but the present invention is not limited thereto.

Production example of base polymer Methyl methacrylate (MMA) and glycidyl methacrylate (GMA) were mixed at a molar ratio of 6=4, ethyl cellosolve was added as a solvent to the mixture to give a concentration of 40% by weight, and asoisobutylene was added as a catalyst. Solution polymerization was carried out at 60° C. in a nitrogen gas atmosphere in the presence of nitrile. Thereafter, acrylic acid was added at 1 epoxy equivalent per epoxy equivalent in the resulting copolymer.
．． After the acid value became constant, 0.8 mole of tetrahydrophthalic anhydride was further reacted. Analysis of the base polymer obtained by this reaction revealed that the weight average molecular weight was 30,000, the softening point was 60°C,
The acid value was 100.

Examples 50 parts by weight of the base polymer produced in Production Example, 30 parts by weight of trimethylolpropane triacrylate, 3 parts by weight of 2-methyl[4-(methylthio)phenyl]-2-morpholino-1-propane, 4.4'- Diethylaminobenzophenone 0.5 parts by weight, silica 5 parts by weight, talc 10 parts by weight, cyanine green 0.5 parts by weight, KS-
661: manufactured by Shin-Etsu Chemical Co., Ltd., 31 parts by weight of a silicone antifoaming agent was kneaded in a roll mill to obtain a photosensitive resin composition.

The effects of the photosensitive resin composition of the present invention obtained in this example are as follows.

The photosensitive resin composition was applied to a thickness of 30 μm by screen printing over the entire surface of a copper-clad laminate on which a surface-treated pattern had been formed in advance. After that, it was dried in a hot air circulation dryer at 70°C for 20 minutes, a negative film with the desired pattern was attached to it, and the intensity at the main wavelength of 365 nm was 25 mW/
After exposure to cnl ultraviolet rays for 20 seconds, the film was developed with a 1% aqueous sodium carbonate solution for 60 seconds, and then dried in a hot air circulating dryer at 150° C. for 30 minutes.

The composition of this example had no tackiness after drying.

As a result, a completely developed and precise pattern corresponding to negative film was obtained. The dry coating strength is 5H, which shows good flexibility, adhesion, methylene chloride resistance, and hydrochloric acid resistance, and the coating remains strong even after 3 cycles of immersion in a 260"C solder bath for 30 seconds. No change was observed, and it was found that the basic characteristics as a liquid solder resist were fully satisfied.

C Effects of the Invention] The photosensitive resin composition of the present invention contains a compound obtained from the above-mentioned specific epoxy group-containing copolymer as a base polymer, so it has good photocurability, heat resistance, and chemical resistance. ,
It has excellent flexibility, adhesion, coating hardness, electrical properties, etc., and can be used not only as a one-component liquid solder resist with no safety or solvent problems, but also as a paint, photosensitive adhesive, and plastic relief. It is an extremely useful composition that can be used in a wide range of applications such as materials and printing materials.

Claims (1)

[Claims] 1. General formula [I] ▲ Numerical formula, chemical formula, table, etc.▼ [I] (In the formula, R_1 is a hydrogen atom or a methyl group, and R_2 is an aliphatic hydrocarbon having 1 to 6 carbon atoms. ) and the general formula [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] (In the formula, R_1 has the same meaning as above, and R_3 has 1 to 12 carbon atoms. 0.8 to 1.2 moles of acrylic acid per 1 epoxy equivalent of this copolymer is reacted with a copolymer with a compound represented by (representing an aliphatic hydrocarbon group or an aromatic hydrocarbon group). After that, a base polymer having a weight average molecular weight of 20,000 to 70,000, a softening point of 35 to 130°C, and an acid value of 50 to 150 obtained by further reacting with a polybasic acid anhydride, a diluent, and a sensitizer. A photosensitive resin composition comprising: 2. The molar ratio of the compound represented by the general formula [I] and the compound represented by the general formula [II] constituting the copolymer is 4.
The photosensitive resin composition according to claim 1, which has a ratio of 0:60 to 80:20. 3. The photosensitive resin composition according to claim 1, wherein the diluent is an unsaturated compound having a boiling point of 100° C. or higher and having at least two methacryloyl groups or acryloyl groups. 4. Base polymer: 30 to 70 parts by weight, diluent: 30 parts by weight
The photosensitive resin composition according to claim 1, comprising 70 parts by weight and 1 to 10 parts by weight of a sensitizer.