JPH02135350A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain a photosensitive resin compsn. having high resolution and ensuring superior work efficiency by using a prepolymer of an unsatd. compd., a monomer of a multifunctional unsatd. compd., a radical photopolymn. initiator, epoxy resin and a cationic photopolymn. initiator as essential components. CONSTITUTION:This photosensitive resin compsn. contains 100pts.wt. prepolymer of an unsatd. compd. such as diallyl phthalate, 1-50pts.wt. monomer of a multifunctional unsatd. compd. having >=2 ethylene bonds in the molecule, 0.5-20 pts.wt. radical photopolymn. initiator, 5-30pts.wt. epoxy resin and 1-10pts.wt. cationic photopolymn. initiator based on 100pts.wt. epoxy resin. The diallyl phthalate prepolymer is also called beta-polymer and is solid in an ordinary state. The pref. mol. wt. of the prepolymer is 3,000-30,000 because satisfactory developability is obtd. This photosensitive resin compsn. solidifies well at the time of exposure and can be developed with a chlorine-contg. solvent. A body hardened by exposure has improved heat resistance and insulation resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a photosensitive resin composition, and particularly to a photosensitive resin composition for manufacturing printed wiring boards that has easy workability and excellent film properties. Regarding.

[Conventional technology]

It is already well known that thermosetting epoxy resin inks can be used as resist materials such as solder resists for manufacturing printed wiring boards.

On the other hand, when considering a solder resist as a resist material, there is a strong demand for improvement in the pattern accuracy of the solder resist formed on a circuit as the density of wiring increases.

In order to meet this demand, instead of thermosetting resist,
Attempts to obtain a highly accurate resist pattern by exposing and developing a photosensitive solder resist have been proposed.
Proposals regarding this type of resist material include, for example, Japanese Patent Publications No. 40451/1983 and Japanese Patent Publication No. 30969/1989.

The above-mentioned Japanese Patent Publication No. 51-40451 discloses (a) a photopolymerizable unsaturated compound containing at least two terminal ethylene groups, (b1-primary polymerization sensitizer, (cl) a compound containing at least two epoxy groups, and ( d) Discloses a photosensitive resin composition consisting of dicyandiamide or containing these as a main component.In addition, the above-mentioned Japanese Patent Publication No. 52-30969 discloses:
A polyfunctional vinyl monomer system comprising at least one photopolymerizable polyfunctional vinyl monomer, a photosensitizer that initiates photopolymerization of the polyfunctional vinyl monomer system upon exposure, and a bisphenol large epoxy resin. , an epoxy novolak type resin or a mixture thereof, a crosslinkable polymer system comprising a B-staged epoxy resin, and an anhydride curing agent for said polymer system that is inherently insensitive to said photopolymerization action. Alternatively, a photosensitive dielectric composition comprising dicyandiamide and an inert solvent for dissolving the above components is disclosed.

[Problem to be solved by the invention]

However, although the above-mentioned conventional technology enables formation of a resist pattern by exposure and development and has good film properties, sufficient consideration was not given to workability, which is an important factor in printed wiring board manufacturing. .

In other words, conventional photosensitive resin compositions use epoxy resins and compounds thereof in order to improve adhesion to copper foil, chemical resistance, and heat resistance. Since these resins are thermally polymerized using an amine curing agent, they must be subjected to high-temperature heating in addition to UV light irradiation. In addition, when using an amine-based curing agent that starts reacting at low temperatures, it has poor thermal stability and the resin hardens during pre-drying to improve the close exposure with the film negative mask. There was a fatal problem in that pattern formation by development became impossible.

An object of the present invention is to solve the various problems seen in the above-mentioned conventional techniques, and to provide a high-resolution photosensitive resin composition that maintains good film properties and has excellent workability. .

[Means to solve the problem]

The above purpose is to combine a photosensitive resin composition with a prepolymer of an unsaturated compound, such as a prepolymer of diallyl phthalate, a monomer of a polyfunctional unsaturated compound, a photoradical polymerization initiator, an epoxy resin, and a former cationic polymerization initiator. This can be achieved by making a resin composition consisting of or having these as main components.

The prepolymer of diallyl phthalate in the above composition is β-
Also called a polymer, it is normally solid. For example, its detailed properties and manufacturing method are described in "Diallyl Phthalate Resin" by Naoki Yoshimi, published by Nikkan Kogyo Shinsekisha (1972), and can be obtained from, for example, Osaka Sodami. The diallyl phthalate prepolymer used in the present invention preferably has a molecular weight of 3,000 to 30,000 because it provides good developability, but is not necessarily limited to this range.

In addition, the polyfunctional unsaturated compound in the resin composition has at least two or more ethylene bonds in the molecule, and examples of such compounds include unsaturated carboxylic acids and polyhydroxy compounds with divalent or higher valences. Examples include compounds obtained by an esterification reaction with. here,
Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, etc.
Examples of polyhydroxy compounds having a valence of two or more include ethylene glycol, propylene glycol, triethylene glycol, hydroxynon, and pyrogallol. Furthermore, epoxy acrylate or epoxy methacrylate produced by a reaction between an epoxy resin and acrylic acid or methacrylic acid can be mentioned. Note that the above examples do not limit the addition of monofunctional unsaturated compounds, and if necessary, a mixture of polyfunctional unsaturated compounds can also be used.

In addition, the photoradical polymerization initiator in the resin group and acid is
Acetophenone and its derivatives, penzophenone and its derivatives, benzyl and its derivatives, thioxanthone and its derivatives, benzoin and its derivatives,
α-aminoketones represented by ketocoumarin and its derivatives, tetramethylthiuram monosulfide, 1-human O-oxycyc-O-hexylphenyl ketone, 2-methyl-1-(4-(methylthio)phenyl]-2-morpholino-propane-1IC) Compounds, etc.

If necessary, a mixture of the above compounds can be used, and if necessary, an aromatic amine compound can also be added for the purpose of improving the action of the photoradical polymerization initiator.

Further, the epoxy resin in the resin composition has an average content of 1
Those having two or more epoxy groups per molecule, for example, polyhydric phenols such as bisphenols, halogenated bisphenols, catechol, resorcinol, etc., or polyhydric alcohols such as glycerin, and epichlorohydrin are basicized. Polyglycidyl ether or polyglycidyl ester obtained by reacting in the presence of a catalyst, epoxy novolac obtained by condensing a novolac type phenol resin and epochrohydrin, epoxidized polyolefin epoxidized by peroxidation method, epoxidized Polybutadiene, dicyclopentagenated oxide, epoxidized vegetable oil, etc. can be used. Further, a cycloaliphatic epoxy resin obtained by epoxidizing an unsaturated fatty acid ester or a butadiene polymer or copolymer with peracetic acid can also be used. Furthermore, if necessary, it is also possible to improve the properties of the epoxy resin and use a mixture.

Further, the original cationic polymerization initiator in the resin composition is U
By irradiating the epoxy resin with V″/l, it generates bouton destruction, Lewis acid, and radicals, and cures the epoxy resin with light. A salt can be used.Also, a sensitizer can be used in combination.Aromatic sulfonium salts are particularly desirable because they react quickly and have good thermal stability.The general formula of aromatic sulfonium salts is It is as follows.

(M-m PF, s Br3, 8bF, ) Furthermore, the resin composition of the present invention contains an organic solvent as a diluent, a coloring agent, an antifoaming agent, a filler, and a thixotropic agent, if necessary. be able to. However, the inclusion of these is not an element that characterizes the present invention.

Among these, suitable examples of MS agents include high temperature point solvents such as cellosolve, cellosolve acetate, methyl cellosolve, butyl cellosolve, carpitol, methyl carpitol, butyl carpitol, and terpineol. However, acetone,
Methyl ethyl ketone, ethanol, etc. can also be used.

Further, as the colorant, a coloring material such as phthalocyanine green or phthalocyanine blue may be used as appropriate.

As the antifoaming agent, an organosilicon compound with siloxane bonds, typified by silicone oil, is used.

The filler is added to the resin composition as an inorganic filler, and a fine powder of silica, alumina, talc, etc. is used.

The thixotropic agent is used to improve the viscosity, particularly the thixotropy, of the resin composition, and it is desirable to use ultrafine powdered silica.

The content of the components of the photosensitive resin composition of the present invention has been explained above, and the preferred composition ratio is 100:iat parts of the diallylphthalate prepolymer to L~50 parts of the polyfunctional unsaturated compound monomer, i! ! < Part f, photoradical polymerization initiator 0.5-20 parts IJK-ffi, epoxy resin 5-303 m M, 1-10 parts of photoradical thionic polymerization initiator per 100 parts by weight of epoxy resin.

Note that the lower and upper limits of the above composition are determined to ensure that the photosensitivity of the resin composition characteristics is not insufficient, that dense layer exposure is possible, and that heat resistance and brazing resistance (especially insulation resistance) are ensured. This is the value that can be obtained as a condition.

[Effect]

Since the photosensitive resin composition according to the present invention contains a large amount of diallyl phthalate prepolymer which is solid in normal state, fluidity can be imparted to the composition by adding a solvent, and it can also be used for screen printing. It can also be easily applied onto a substrate by a method. Further, since the resist is easily solidified by pre-drying after coating and before exposure, it is possible to expose the resist surface with a negative mask in close contact with the resist surface.

In addition, the polyfunctional unsaturated compound and the photoradical 1 initiator in the resin composition of the present invention are added so that the photopolymerization reaction with the diallylphthalate prepolymer is completed within a practical time. It acts to prevent the photocured part from dissolving or swelling in the developer during the development process. In addition, epoxy resins and photocationic polymerization initiators can also be
Although the photocationic polymerization initiators currently being developed undergo 1001 m polymerization when exposed to light, the wavelength of the UV light they react with is @wavelength, so JV light passing through a negative mask
It does not react and does not lead to pattern formation.

Therefore, by using the polyfunctional unsaturated compound and the photoradical polymerization initiator in the resin composition, it becomes possible to form a fine pattern in a short time using UV light.

Moreover, the epoxy resin and the photocationic polymerization initiator in the resin composition of the present invention can improve the close layering property with the copper foil on the printed circuit board. Moreover, since the epoxy resin can be easily polymerized with UV light after pattern formation, workability is excellent.

Furthermore, compared to amine-based curing agents, photocationic polymerization initiators have better thermal stability. It was also found that the heat resistance and electrical properties of the cured resist were maintained at the same level or better than those cured with a photocationic polymerization initiator.

In addition, regarding development, it was discovered that only a combination of a diallylphthalate prepolymer, a polyfunctional unsaturated compound, and an epoxy resin can be dissolved in a chlorinated solvent such as 1.1.1-trichloroethane, and
We have also found that the surface of the exposed cured product does not dissolve during pattern formation due to the addition of a photo-cationic polymerization initiator. This made it possible to develop with a chlorinated solvent.

Since the photosensitive resin composition of the present invention has the above-mentioned actions and characteristics, it is particularly suitable for manufacturing high-density, low-cost printed wiring, but its effectiveness also applies to other uses. It's not something you lose.

〔Example〕

Examples of the photosensitive resin composition of the present invention will be described below along with comparative examples.

Example 1 First, a resin composition containing the following B) to (E) as main components was prepared. The blending ratio of each component is as shown in Table 1.

(a) Diallyl phthalate prepolymer (01 to IJ methylpropane trimethacrylate (trifunctional methacrylate) (c) 2-methyl-1-(4-(methylthio)phenyl-2-morpholino-propane-1 Polymerization initiator) Epoxy resin (e) Bis-(4-(diphenylsulfonio)phenyl)sulfide-bis-hexafluorophosphate (photocationic polymerization initiator) Here, as the diallylphthalate prepolymer, The prepolymer (manufactured by Osaka Soda@, trade name Isodap) with an average molecular weight of 7,000,
epoxy tree) 1 effect is phenol novolac type epoxy (manufactured by Yuka Shell Epoxy ■, product name Epicote 15)
2) was used.

The resin composition was prepared according to the following procedure at a blending ratio within the range of the present invention. That is, first, (e) to (e) were mixed and heated and stirred at about 80° C. for 30 minutes. At this time, in order to improve the coating properties of the composition, a solvent (butyl cellosolve acetate), a coloring agent (phthalocyanine green), and an antifoaming agent (silicone oil) were added to i! The photosensitive resin composition of the present invention was obtained by adding 1 m of the resin and dispersing and dissolving it in the above main component.

The above A4 fat composition was printed over the entire surface of the printing board using a screen printing machine using a 180 mesh stainless steel screen plate, and then pre-dried at about 80° C. for 30 minutes. In this state, when the resin surface is solidified and a negative mask can be exposed in close contact with the resin surface, it is determined that the contact exposure is possible.

Next, the film was exposed to ultraviolet light through a negative mask using a 400W high-pressure mercury lamp for a period of 0.5 to 2 minutes, followed by spray development with 1,1,1-1 dichlorethane. After the resin pattern was formed by development, the bottom surface of the resin layer was observed under a microscope, and if the resist did not swell in this state, it was determined that the pattern formation was good.

Regarding the sample after the development, the resist was further directly exposed to ultraviolet light for 2 to 4 minutes using a 400 W high-pressure mercury lamp.

Further, the printed layout board was subjected to soldering at 260° C. for 10 seconds and cooled to room temperature in air. This solder immersion was repeated five times, and the heat resistance was evaluated based on whether or not the resist layer peeled off.

Furthermore, volume insulation resistance was measured based on %JIS.

Table 1 shows the characteristics of the resin layer obtained by the above evaluation method.

Comparative Example 1 Printing was carried out in the same manner as in Example 1, using a resin composition containing two amine curing agents, triethylenetetramine and dicyandiamide, instead of the photocationic polymerization initiator in the composition of Example 1. Manufactured powder board. However, instead of exposure to ultraviolet light after development, heat curing was performed at 160° C. for 1 hour. Next, the obtained resin layer was evaluated under the same conditions as in Example 1. The results are shown in Table 1.

From the results in Table 1, in the case of Example 1, all showed superior properties, whereas in Comparative Example 1, an amine-based curing agent (triethylenetetramine) that reacts at low temperatures was used.
When using epoxy, the reaction of the epoxy starts during pre-drying, making it impossible to form a pattern; however, when using an amine-based curing agent (dicyandiamide) that reacts at high temperatures, pattern formation is possible. However, it is known that heat resistance is questionable and that amine curing agents have inferior volume insulation resistance compared to cationic curing agents.

Example 2 A resin composition containing the following (G) to (E) as main components was prepared in Example 1.
It was prepared in the same manner as in the case of . The blending ratio of each component is as shown in Table 2.

) diallyl phthalate prepolymer (average molecular ii
3,500, manufactured by Osaka Shikushoku@, trade name: Daisodatsubu L) (b) Polyfunctional unsaturated compound @ (total of 5 acrylates and methacrylates shown in Part 2-2) (c) Benzoin isopropyl ether (former radical polymerization initiator) ) Epoxy resin (e) Bis-[:4-(diphenylsulfonio)phenyl]sulfide bis-hexafluoro antimonate (photocationic polymerization initiator) The properties of the resulting resin layer are shown in Table 2. show. It is known that the same characteristics as in Example 1 are obtained when various polyfunctional unsaturated compounds are used.

Comparative Example 2 In the composition of Comparative Example 2, instead of the cationic photopolymerization initiator, a porridge composition containing two amine-based curing agents, triethylenetetramine and dicyandiamide, was used, and the same procedure as in Comparative Example 1 was carried out. A printed wiring board was manufactured.

The results of the temporal Jf value of the resulting resin layer are shown in Table 2, and as in the case of Comparative Example 1, satisfactory #f properties could not be confirmed.

〔Effect of the invention〕

As described above, by making the photosensitive resin composition of the present invention, screen printing is possible, it shows sufficient solidification upon exposure, and it can be developed with a chlorine bath agent. Furthermore, it was possible to obtain a photosensitive resin composition that is effective in improving the heat resistance and insulation resistance of the cured product. In addition, since a vague resist pattern can be obtained with a deep UV exposure, the working time can be reduced to W4m.

Table 2 Having these characteristics means that it is possible to solve the problems seen in the prior art and form a high-density resist pattern;
This shows that productivity can be clearly improved and costs can be reduced in the production of printed wiring boards.

Claims (1)

[Claims] 1. Consisting of a prepolymer of an unsaturated compound, a monomer of a polyfunctional unsaturated compound, a photoradical polymerization initiator, an epoxy resin, and a cationic photopolymerization initiator, or consisting of these as the main component A photosensitive resin composition. 2. The unsaturated compound prepolymer is a diallyl phthalate prepolymer with a molecular weight of 3,000 to 30,
000, and the monomer of the polyfunctional unsaturated compound is at least one polyfunctional unsaturated compound selected from acrylate or methacrylate of a hydroxy compound, oligoester acrylate or methacrylate, epoxy acrylate or methacrylate, The composition ratio is 1 to 50 parts by weight of a polyfunctional unsaturated compound monomer, 0.5 to 20 parts by weight of a photoradical polymerization initiator, and 5 to 30 parts by weight of an epoxy resin to 100 parts by weight of diallylphthalate prepolymer. In addition, 1 part by weight of photocationic polymerization initiator per 100 parts by weight of epoxy resin.
2. The photosensitive resin composition according to claim 1, wherein the amount is 10 parts by weight.