JPH0332780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a photopolymerizable photosensitive resin composition for image formation.

(Prior art) Conventionally, a resin composition consisting of a binder made of a polymeric material, a photopolymerizable monomer, a photopolymerizable sensitizer, etc. is applied or coated onto a substrate, and actinic light such as ultraviolet rays is irradiated through a negative image. It is known that the insolubilized image can be developed on a substrate by polymerizing or crosslinking the areas that are exposed to the light beam and making them insolubilized in the solvent, and eluating the areas that are not exposed to the light beams. It is used for manufacturing pre-printed wiring boards.

However, the image coating obtained with the above composition has insufficient solvent resistance, chemical resistance, heat resistance and mechanical strength, and its use as a protective coating is limited.

For example, these films can withstand neutral and weakly acidic solutions, but cannot withstand strongly acidic and alkaline solutions, thus limiting the types of processing solutions for etching, plating, and the like. Also, totoluene, trichlene,
It is weak against organic solvents such as methyl ethyl ketone and has insufficient heat resistance and mechanical strength, so it cannot be used as a permanent protective film.

In addition, systems containing epoxy compounds and their curing agents have been proposed for the purpose of forming permanent protective films, but these have a short pot life at room temperature, require high temperatures and long periods of time to cure, and may warp the substrate. or cause metal corrosion.

In Japanese Patent Publication No. 52-43092, Japanese Patent Publication No. 52-43091, Japanese Patent Publication No. 56-3539, etc., an acid component is contained in a copolymer binder for the purpose of forming a permanent protective film. We are trying to accelerate curing, but curing is insufficient under normal conditions.
Weak in soldering heat resistance, solvent resistance, and alkali resistance,
Furthermore, the cooling and heating cycling characteristics cannot be said to be sufficient.

(Object of the Invention) The present invention solves the above-mentioned conventional drawbacks, and provides a photosensitive resin composition that has excellent storage stability, can be sufficiently cured with short heating, and is suitable for forming a permanent protective film. The purpose is to provide something.

(Summary of the Invention) The summary of the present invention is as follows: (a) a photopolymerizable unsaturated compound having substantially at least two terminal ethylene groups, (b) a photopolymerizable sensitizer, and (c) the following general formula () A linear polymer compound obtained by polymerizing a compound represented by and a polymerizable compound containing an epoxy group as components. (R ₁ is a group selected from hydrogen, methyl, ethyl, and halogen; at least one of R ₂ , R ₃ , and R ₄ is a hydroxyl group, and an alkoxyl group, an allyloxy group, an acryloyloxy group, and a methacryloyloxy group) A photosensitive resin characterized in that it is an aliphatic hydrocarbon group containing a group selected from the group consisting of groups, and the other is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or has these as its main component. present in the composition.

(Structure of the Invention) The unsaturated compound (a) in the present invention substantially has at least two terminal ethylene groups. Substantially having at least two terminal ethylene groups may include a compound having only one terminal ethylene group, a compound having three or more terminal ethylene groups, and the average number of terminal ethylene groups as a whole. This means that one compound has at least two.

As the unsaturated compound (a), acrylic esters or methacrylic esters of polyhydric alcohols are most suitable, and specifically, triethylene glycol, tetraethylene glycol, ethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, Examples include acrylic acid or methacrylic acid esters such as neopentyl glycol. The amount of this component used is preferably 10 to 90% by weight, more preferably 15 to 60% by weight in the photosensitive resin composition.

The sensitizer (b) in the present invention is one that initiates polymerization of the unsaturated compound (a) by irradiation with actinic rays, and in some cases may act as the main sensitizer and the action of the main sensitizer. Combinations of increasing secondary sensitizers may be used.

As the sensitizer (b), conventionally used sensitizers can be used, but among them, phenylketone-based sensitizers are preferred, and specifically, benzophenone,
p-aminophenyl ketones such as p,p-bis(dimethylamino)benzophenone (hereinafter referred to as Michler's ketone), benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, benzyl anthraquinone, 2-methyl anthraquinone Quinone, 2-ethyl anthraquinone, 2-
Examples include t-butyl anthraquinone and 2-amino anthraquinone.

The above-mentioned sensitizers (b) have similar effects, and by combining those with different absorption ranges of actinic rays, the polymerization initiation efficiency can be improved and the exposure time can be shortened. Particularly suitable is a mixture of benzophenone and mitler ketone.

The amount of the increase/decrease agent (b) above is determined in the photosensitive resin composition.
Preferably 0.01-15% by weight, more preferably 0.1
~10% by weight.

The linear polymer compound (c) in the present invention is obtained by polymerizing an epoxy group-containing polymerizable compound (c-1) and a compound (c-2) represented by the general formula () as components. It is.

Polymerizable compound containing epoxy group (c-1)
This includes, for example, glycidyl methacrylate, glycidyl acrylate, and polymerizable oligomers obtained from these.

Conventionally, in photosensitive resin compositions using epoxy compounds for the purpose of forming a permanent protective film, boron trifluoride monoethylamine, boron trifluoride benzylamine complex, boron tetrafluoride acid are used as latent curing agents for the epoxy compound. There are salts, adipic acid, dihydrazide, ethyl aminoborane, phenylenediamine-zinc bromide complex, dicyandiamide, etc., but they have short pot life at room temperature and poor storage stability.

As a latent curing agent with a long pot life at room temperature, p,
p'-diaminodiphenylmethane, P,P'-diaminodiphenyl sulfonic acid, 2-ethyl-4-ethylimidazole, etc. have also been found, but because they require high temperatures and long periods of time to cure, they cannot be used for printed wiring boards. When used in manufacturing, the substrate may warp or the processing time may become longer, which is undesirable.

Further, the conventional latent curing agent described above is not suitable for manufacturing printed wiring boards because it may diffuse into the metal surface of the substrate and adversely affect the electrical properties of precision electrical circuits.

Therefore, as a result of intensive research, the present inventor has developed a polymerizable compound (c-1) containing an epoxy group as described above and a compound represented by the following general formula () for the purpose of solving the above technical problem. A linear polymer compound (c) obtained by polymerizing (c-2) with (c-2) was discovered.

Compound (c-2) is an amine imide compound represented by the following general formula ().

(R ₁ is a group selected from hydrogen, methyl, ethyl, and halogen, and at least one of R ₂ , R ₃ , and R ₄ is a hydroxyl group, an alkoxyl group, an allyloxy group, an acryloyloxy group, and a methacryloyloxy group. In the compound (c-2), R ₂ , R ₃ , R ₄ The number of carbon atoms in the aliphatic hydrocarbon is preferably 6 or less, and may contain a carbon-carbon double bond, since the smaller the number of carbon atoms, the better the curability, heat resistance, etc. are.

The protective film obtained by curing the photosensitive layer containing the linear polymer compound c containing the above-mentioned compound (c-2) as one component does not have an adverse effect on the substrate surface because the constituent materials do not bleed out. Moreover, the above-mentioned protective coating has excellent heat resistance, solvent resistance, acid resistance, alkali resistance, and the like. The reason for this is that when the photosensitive layer is cured, the epoxy moiety in the linear polymer c crosslinks, and the isocyanate generated from the amine imide moiety contained in the side chain of the linear polymer c becomes a crosslinking point. This seems to be because crosslinking progresses to a high degree in the shaped polymer compound c.

The compound (c-2) represented by the general formula () includes 1,1-dimethyl-1-(2-hydroxy-3-butoxypropyl)amine-methacrylimide, 1,1-dimethyl-1-(2- Hydroxy-3-allyloxacypropyl)amine-methacrylimide, 1,1-dimethyl-1-(2-hydroxy-3-acryloyloxypropyl)amine-methacrylimide, 1,1-dimethyl-1
-(2-hydroxy-3-methacryloyloxypropyl)amine-methacrylimide, and the like.

The linear polymer compound (c) is obtained by polymerizing the above-mentioned epoxy group-containing polymerizable compound (c-1) and the compound (c-2) represented by the general formula (). The ratio of the components is preferably 70% by weight or less for the polymerizable compound (c-1) containing an epoxy group;
2) is preferably 15% by weight or less, and the remaining portion is preferably copolymerized with a polymerizable compound other than the above, such as methyl methacrylate, methyl acrylate, butyl methacrylate, butyl acrylate, or styrene. Also, the molecular weight of linear polymer compound (c) is 10
~300,000 is preferable.

The amount of linear polymer compound (c) used is preferably 10 to 90% by weight, more preferably 10 to 90% by weight in the photosensitive resin composition.
It is 30-60% by weight.

The photosensitive resin composition of the present invention consists of the above-mentioned unsaturated compound (a), photopolymerization increaser/decrease agent (b) and linear polymer compound (c), or is composed mainly of these,
Furthermore, epoxy resins and oligomers having epoxy groups used in conventional photosensitive resin compositions may be used in combination. Depending on the type and amount of these additive components, the flexibility of the composition can be controlled to an appropriate degree, improving the normal pressure or vacuum lamination properties on substrates, and creating a permanent protective film that can be formed even on substrates with uneven surfaces. It adheres well, making it easier to embed precision circuits, etc. Furthermore, even when the board is immersed in a solder bath, floating and peeling due to the generation of air bubbles are eliminated. Furthermore, the flexibility of the cured protective film can be controlled by controlling the type and amount of the epoxy resin and oligomer having an epoxy group, and the thermal cycling properties are significantly improved.

Specifically, the epoxy resins and oligomers having epoxy groups include epoxy resin prepolymers Epicote 828, Epicote 1001, Epicote 1004, Epicote 1007 (all trade names, manufactured by Ciel), Araldite ECN-1280, Araldite ECN -1237 (all product names, manufactured by Ciba Geigy), etc. The amount of these epoxy resin prepolymers used is 5 to 50% of the photosensitive resin composition.
80% by weight is preferred, more preferably 5-50% by weight
is within the range of

In addition to the above-mentioned essential components or optional components, the photosensitive resin composition of the present invention can further contain secondary components for various purposes. That is, a thermal polymerization inhibitor for improving storage stability,
These include plasticizers, adhesion improvers, dyes, pigments, and other fillers to improve film properties.

(Action of the invention) The photosensitive resin composition of the present invention has photosensitivity similar to ordinary photosensitive resins, undergoes photopolymerization upon irradiation with actinic rays, and is sufficiently thermally stable at temperatures below 80°C. A permanent protective coating can be formed by conventional methods.

That is, the photosensitive resin composition of the present invention is usually
Prepare a solution by dissolving it in an organic solvent such as methyl ethyl ketone, toluene, methyl cellosolve, or chloroform to a concentration of 60% by weight, and follow the steps below (1).
Alternatively, a photosensitive layer is formed on the substrate to be protected by method (2).

(1) A solution containing a photosensitive resin composition is applied onto a substrate and dried.

(2) A solution containing the photosensitive resin composition is applied to a film such as polyethylene terephthalate and dried. The obtained film is attached to a substrate using a hot roll. In this case, a protective film may be placed over the photosensitive layer of the film for storage.

The substrate on which the photosensitive layer is formed is irradiated with actinic light such as ultraviolet rays through a negative mask, and the exposed areas are cured by photopolymerization and crosslinking. Then 1, 1,
Using 1-trichloroethane or the like, the unexposed areas are eluted and developed. The image-like protective film obtained in this way becomes a corrosion-resistant film for ordinary surface modification processing such as etching and plating, but is further cured by heating at about 150°C for a few minutes to an hour. It forms a permanent protective film with excellent heat resistance and mechanical strength. In the present invention, due to the action of the compound (c-2) represented by the general formula (), the epoxy group of the linear polymer compound (c) or the selectively added epoxy resin prepolymer is heated under mild heating conditions. One of its characteristics is that it hardens quickly and has a sufficiently long pot life before heating. The protective coating is not attacked by solvents such as aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and acetone, and halogenated hydrocarbon solvents such as methylene dichloride, chloroform and trichlene, and is also resistant to strong acids and alkaline aqueous solutions. It also withstands well.
Therefore, it can be used as a permanent protective film such as a solder resist with excellent soldering heat resistance. A protective film having excellent strength can also be formed by post-exposure to ultraviolet light or the like at an intensity of 1 to 3 J/cm ³ prior to heat curing. Further, since the photosensitive resin composition of the present invention has excellent photosensitivity and chemical and physical strength, it can also be used as a photosensitive adhesive, a photosensitive paint, a plastic relief, and a printing plate material.

(Example) Examples of the present invention will be described below. In addition, “department”
means "parts by weight".

<Example 1> Methyl methacrylate/glycidyl methacrylate/1,1-dimethyl-1-(2-hydroxy-3-butoxypropyl)amine-methacrylimide copolymer (weight ratio 60/35/5) (Mw=24
60 parts pentaerythritol triacrylate 30 parts benzophenone 3 parts Michler's ketone 0.5 parts p-methoxyphenol 0.5 parts methyl ethyl ketone 200 parts The photosensitive resin composition obtained with the above formulation was applied and dried on a 25 μm thick polyethylene terephthalate. , a photosensitive layer with a thickness of 50 μm was formed. It was laminated under pressure on a cleaned copper plate using a hot roll. Then, 100mJ/
cm ² of ultraviolet light was irradiated. The polyethylene terephthalate film was peeled off, and 1,1,1-trichloroethane was sprayed for 90 seconds to elute the unexposed areas and development was performed. Next, heat treatment was performed at 150° C. for 10 minutes, and a protective film with a precise image corresponding to a negative mask was obtained. This protective film showed no change even when immersed in methyl ethyl ketone, acetone, chloroform, trichlene, methanol, 10% sulfuric acid aqueous solution, toluene, and xylene for 1 day, and was further immersed in sodium hydroxide solution with pH 12 at 70°C for 1 day. Even after immersion, no abnormality was observed.

Also, heat and cool to -65℃ and 125℃ for 100 minutes at intervals of 60 minutes.
Even after repeating the test several times and immersing it in a solder bath at 260 to 270°C for 2 minutes, there was no change. Furthermore, this board is 70℃
Even after leaving it for a month, no bleed-out was observed on the surface, and there was no corrosion of the metal. The photosensitive layer formed on the polyethylene terephthalate film was 40
There was no problem in using it even if it was stored at ℃ for 6 months. From the above, it was found that the obtained protective film can be satisfactorily used as a resist for etching, plating, strong alkaline electroless plating, and as a solder resist that requires soldering heat resistance.

<Example 2> Instead of the copolymer in Example 1, butyl methacrylate/glycidyl methacrylate/
1,1-dimethyl-1-(2-hydroxy-3-
Acryloyloxypropyl)amine-methacrylimide copolymer (weight ratio 40/50/10) (Mw=19
A photosensitive layer was prepared in the same manner as in Example 1 except that 1,000 yen) was used.

The resulting protective film can withstand 50% sulfuric acid aqueous solution,
The solvent resistance was the same as in Example 1, and it was able to withstand 150 repeated heating and cooling tests and a solder bath at 270 to 280°C for 2 minutes. Furthermore, this board has a temperature of 2 at 70°C.
No surface bleed-out was observed even after being left for several months.
The 40°C storage stability of the photosensitive layer was also the same as in Example 1, and it was confirmed that it could be used as a solder resist or various resists.

<Example 3> To the composition of Example 2, an epoxy resin prepolymer (Ciba Geigy, Araldite ECN-
1280) was added to prepare a photosensitive layer in the same manner.

It was confirmed that the photosensitive layer had good storage stability at 40°C for more than 6 months, and the solvent resistance and heat resistance of the formed protective film were the same as in Example 2, and could withstand 150 cycles of cooling and heating. . In addition, the laminate on the substrate was sufficiently embedded in even the smallest details even at normal pressure and 100°C, and there was an improvement in this aspect.

<Comparative example> Methyl acrylate/glycidyl methacrylate copolymer (weight ratio 60/40) (Mw = 200,000) 60 parts pentaerythritol triacrylate 30 parts benzophenone 3 parts Michler ketone 0.5 parts p-methoxyphenol 0.5 parts methyl ethyl ketone 200 parts and, A test similar to that of Example 1 was conducted with the addition of 2 parts of dicyandiamide as an epoxy hardener. It was found that the photosensitive material had a short shelf life at 40°C as it began to harden in one week.

Further, after exposure and development, heating at 150° C. for 10 minutes did not provide a sufficient protective film, and neither the solvent resistance nor the heat resistance could withstand the tests of Examples 1 to 3.

The material that was then heated at 150°C for 2 hours was resistant to various organic solvents for several tens of minutes, but cracked within 5 cycles in a cold/hot cycle test.

(Effects of the Invention) As described above, the photosensitive resin composition of the present invention has excellent storage stability, the reaction progresses sufficiently in a short time at a relatively low temperature during curing, and it has excellent solvent resistance and alkali resistance. , a protective film with good heat resistance can be formed.

Claims (1)

[Scope of Claims] 1 (a) Substantially at least 2 terminal ethylene groups
(b) a photopolymerizable sensitizer; and (c) a line obtained by polymerizing a compound represented by the following general formula () and a polymerizable compound containing an epoxy group as components; shaped polymer compound (R ₁ is a group selected from hydrogen, methyl, ethyl, and halogen, and at least one of R ₂ , R ₃ , and R ₄ is a hydroxyl group, an alkoxyl group, an allyloxy group, an acryloyloxy group, and a methacryloyloxy group. A photosensitive resin characterized in that it is an aliphatic hydrocarbon group containing a group selected from the group consisting of groups, and the others are aliphatic hydrocarbon groups or aromatic hydrocarbon groups. Composition.