JPH02173749A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To obtain the compsn. which is excellent in a photosetting property, heat resistance, chemical resistance, flexibility, and electrical characteristics, and is useful as a liquid photoresist which can be developed with a dilute aq. alkaline soln. by using a specific multifunctional epoxy resin. CONSTITUTION:This compsn. contains the reaction product obtd. by bringing polymerizable unsatd. carboxylic acid at 0.8 to 1.2mol% per 1 epoxy equiv. of the epoxy resin expressed by formula I into reaction, then further bringing the reaction product thereof and 0.2 to 1.0mol polybasic acid anhydride into reaction, a diluent, a sensitizer, the epoxy resin, and an epoxy resin hardener. The preferable compounding ratios thereof are successively 40 to 60pts.wt., 5 to 50pts.wt., 3 to 10pts.wt., 10 to 20pts.wt., and 0.5 to 3pts.wt. The photosensitive resin compsn. useful as the liquid photosolder resist having the excellent UV curing property and solder heat resistance is obtd. in this way.

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 photosolder resist with excellent properties.

[Conventional technology]

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

Solder resist is used in the pre-process of soldering electronic 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 protects one circuit conductor from being directly exposed to air and corroded by oxidation and moisture. It also functions as a protective film to prevent damage, and is indispensable.

Conventionally, such solder resists have been formed by screen printing on a substrate and curing with ultraviolet rays or heat. However, printed circuit boards are becoming increasingly finer, more numerous, and more integrated into one board in order to achieve higher density, and as they become more sophisticated at a remarkable pace, the mounting method is also shifting to surface mount technology (SMT). -It has progressed steadily. 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-B-Sho 51-40451 disclose a solder resist composition comprising a bisphenol type epoxy acrylate, a sensitizer, an epoxy compound, an epoxy curing agent, and the like. However, 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 come under the spotlight for 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.

1984 Special Publication as an ultraviolet curable material that can be developed with alkali
No. 40329 and Japanese Patent Publication No. 57-45785 disclose materials in which a base polymer is a reaction product obtained by reacting an epoxy resin with an unsaturated monocarboxylic acid and further adding a polybasic acid anhydride. Further, JP-A-61-243869 discloses a liquid solder resist composition using a novolac type epoxy resin, which has good heat resistance and chemical resistance, and can be developed with a dilute aqueous alkaline solution.

[Problem to be solved by the invention]

The purpose of the present invention is to use a new multifunctional epoxy resin other than the above-mentioned bisphenol type or novolac type epoxy resin to create a material with excellent photocurability, heat resistance, chemical resistance, flexibility, and electrical properties. An object of the present invention is to provide a photosensitive resin composition useful as a liquid photoresist that can be developed with a dilute aqueous alkaline solution.

[Means to solve the problem]

(a) 0.8 per 1 epoxy equivalent of the epoxy resin represented by the structural formula (1)
A reaction product obtained by reacting ~1.2 mol of polymerizable unsaturated carboxylic acid and then further reacting with 0.2 to 1.0 mol of polybasic acid anhydride per 1 epoxy, (b) A photosensitive resin composition developable with a dilute alkaline aqueous solution characterized by containing a diluent, (c) a sensitizer, (d) an epoxy resin, and (e) an epoxy resin curing agent, and a preferred blending ratio thereof. (a) 40-60 parts by weight, (b) 5-50
parts by weight, (c) 3 to 10 parts by weight, (d) 10 to 20 parts by weight, and (e) 0.5 to 3 parts by weight.

Next, the present invention will be explained in detail.

The epoxy resin represented by the structural formula (1) has excellent heat resistance and flexibility. In general, novolak-type epoxy resins have excellent heat resistance, but
Bisphenol-type epoxy resins are said to have excellent flexibility but poor heat resistance. The epoxy resin of structural formula CI) used in the present invention has only the advantages of novolac type and bisphenol type, and also has superior water resistance than other epoxy resins, so the photosensitive resin composition of the present invention is heat resistant. The cured product has excellent properties such as flexibility, flexibility, and insulation resistance after humidification.

Examples of the polymerizable unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid, with acrylic acid being particularly preferred.

In the reaction between the epoxy group and the polymerizable unsaturated carboxylic acid, it is presumed that esterification occurs through the reaction described below. Therefore, the number of epoxy groups and the number of polymerizable unsaturated groups should approximately correspond.

(Epoxy compound) (Polymerizable unsaturated basic acid) (esterified product) As the polybasic acid anhydride used in the present invention, hexahydrophthalic anhydride is 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-ethylhexahydrophthalic anhydride, 4-ethylhexahydrophthalic anhydride, tetrahydrophthalic anhydride thing, 3
-Methyltetrahydrophthalic anhydride.

Preferred examples include 4-methyltetrahydrophthalic anhydride, 3-ethyltetrahydrophthalic anhydride, and 4-ethyltetrahydrophthalic anhydride.

Examples of the diluent (b) include an unsaturated compound having at least two ethylene bonds and an organic solvent, but it is particularly preferable to use a combination of the two. The unsaturated compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, glycerin tri(meth)acrylate, 1.3-propylene di(meth)acrylate, 1゜2
．． 4-butanetrioltri(meth)acrylate, 1
, 4-benzenediol di(meth)acrylate, bis(meth)acrylate of polyethylene glycol having a molecular weight of 200 to 500, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(
meth)acrylate, dipentaerythritol hexa(
meth)acrylate, methylenebis(meth)acrylamide, diethylenetriaminetri(meth)acrylamidebis(methacrylamidopropoxy)ethane,
Bismethacrylamidoethyl methacrylate N-[(β
-hydroxyethyloxy)ethylcoacrylamide,
Divinyl phthalate, divinyl terephthalate, divinylbenzene-1,3-disulfonate, divinylbutane-1゜4-disulfonate, triallyl isocyanurate, tri(meth)acrylic isocyanurate, xylylene bis(diallyl isocyanurate), tris(2,3
-dibromopropyl) isocyanurate, tris(3-
organic solvents include ethylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, ethylene glycol dialkyl ethers, diethylene glycol dialkyl ethers, ethylene glycol monoalkyl ether acetates, and diethylene glycol monoalkyl ethers. Ether acetates, cyclohexanone, tetrahydronaphthalene, petroleum naphtha, etc. are used and are used to dilute it to a state that is easy to apply.

There are no particular limitations on the sensitizer used in the present invention, but 2-methyl-[4-(methylthio)phenylgo-2-
Particularly excellent ultraviolet curability can be obtained by using morpholino-1-propanone as the main component and one or two other sensitizers in combination. Sensitizers used in the above combination include p-phenylbenzophenone, benzyl dimethyl ketal, 2゜4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2
Examples include -isopropylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 4,4'-diethylaminobenzophenone, and p-dimethylaminobenzoic acid ethyl ester.

The epoxy resin (d) used in the present invention is not particularly limited, but compounds having at least two epoxy groups 1 such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, novolac type Epoxy resins, trisglycidyl isocyanuric acid, etc. are preferred, and trisglycidyl isocyanuric acid is particularly preferred. Compared to other epoxy resins, this trisglycidyl isocyanuric acid hardly dissolves in organic solvents, so it has good stability at low temperatures and high reactivity at high temperatures.

Furthermore, since it has a triazine skeleton, it has excellent heat resistance and electrical properties.

There are no particular restrictions on the epoxy resin curing agent (e) used in the present invention, but S-triazine compounds are particularly preferred. For example, melamine, guanamine, acetoguanamine, benzoguanamine, ethyldiamino-s-triazine, 2,4-diamino-S-triazine, 2,4-diamino-6-tolyl-S-triazine, 2,4-diamino-6-xylyl -8-triazines and their analogs are preferred. This s-triazine compound not only serves as a latent curing agent for the epoxy resin, but also has the effect of improving the adhesive strength between the resist and the substrate and preventing electrolytic corrosion and discoloration of copper.

The photosensitive resin composition of the present invention includes (a) (b) (c)
(d) Consists of component (e), with a blending ratio of 40 to 60 parts by weight of the reaction product of (a) and 5 to 50 parts of the diluent of (b).
Parts by weight, 3 to 10 parts by weight of the sensitizer (C), 10 to 20 parts by weight of the epoxy resin (d), and 0.5 to 3 parts by weight of the epoxy resin curing agent (e) are preferred. , and various additives as necessary, such as silica, talc,
Extender pigments such as alumina, calcium carbonate, clay, and Aerosil, coloring pigments such as chrome phthalo yellow and cyanine green, silicone and fluorine-based antifoaming agents, leveling agents, antioxidants, and the like can be added.

The photosensitive resin composition of the present invention described above is coated on a substrate to a desired thickness, heated at 60 to 80°C for 15 to 60 minutes to volatilize the organic solvent, and then formed into a desired film with a transparent image area. 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 cross-link 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 here is generally a 0.5 to 5% by weight aqueous sodium carbonate solution, but of course other alkalis can also be used. The pattern thus obtained was later exposed to ultraviolet light or 100-200 nm to improve heat resistance.
It is desirable to react (secondary curing) by applying heat at 00°C or far infrared rays.

Examples of the present invention are shown below, but the present invention is not limited thereto.

<Synthesis Example 1> Epoxy acrylate was obtained by reacting 1 mole of acrylic acid with 1 epoxy equivalent of the epoxy resin of [1] using 30% by weight of butyl cellosolve acetate as a solvent. One hydroxyl equivalent of this epoxy acrylate was reacted with 0.5 mol of tetrahydrophthalic anhydride until the acid value reached the theoretical value.

This reaction product is designated as (a-1).

Synthesis Example 2> A reaction product [a-23] was obtained in the same manner as in Synthesis Example 1 except that 0.5 mol of hexahydrophthalic anhydride was used in place of tetrahydrophthalic anhydride in Synthesis Example 1.

Examples 1 to 6 The ingredients shown in Clothing-1 below were blended and kneaded in a roll mill to obtain photosensitive compositions.

(Leaving space below) 1) Silicone antifoaming agent manufactured by Shin-Etsu Chemical Co., Ltd. 2) The entire surface of a copper-clad laminate that has been patterned with surface-treated photosensitive resin compositions of Examples 1 to 6 of cresol novolac type epoxy resin The film was applied to a thickness of 20 to 30 μI by screen printing.

After that, it is dried for 20 minutes in a hot air circulation dryer at 70°C, and the negative film of the desired pattern is adhered to the wavelength 365n.
The film was exposed to ultraviolet light with an intensity of 25 mV/cJ for 20 seconds, and developed with a 1% sodium carbonate aqueous solution for 60 seconds.
Then, it was heated and cured for 30 minutes in a hot air circulation dryer at 150°C.

All of the compositions of Examples 1 to 6 had no tack after drying, and a completely developed and precise pattern corresponding to a negative film was obtained, and the coating film had a hardness of 5 H, flexibility,
It has good adhesion, methylene chloride resistance, and hydrochloric acid resistance, and has excellent insulation resistance after humidification. No change was observed in the coating film even after immersion in a 260°C solder bath for 30 seconds, making it suitable as a solder resist. It was found that the characteristics were fully satisfied.

〔effect〕

From the above results, the photosensitive resin composition of the present invention has excellent heat resistance, chemical resistance, and adhesion, and can be used not only as a solder resist, but also for paints, photosensitive adhesives, plastic relief materials, and printing materials. It can be used for a wide range of purposes such as materials.

Claims (1)

[Claims] 1. (a) Structural formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] 0.8 per 1 epoxy equivalent of the epoxy resin represented by [I]
A reaction product obtained by reacting ~1.2 mol of α/β unsaturated carboxylic acid and then further reacting with 0.2 to 1.0 mol of polybasic acid anhydride per 1 epoxy equivalent, ( b) diluent, (c) sensitizer, (d
) an epoxy resin; and (e) a photosensitive resin composition comprising an epoxy resin curing agent. 2. (a) 40 to 60 parts by weight, (b) 5 to 50 parts by weight, (c) 3 to 10 parts by weight, (d) 10 to 20 parts by weight,
The photosensitive resin composition according to claim 1, characterized in that it contains 0.5 to 3 parts by weight of (e).