JPH036496B2 - - 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 polymer material, a polymerizable monomer, a polymerization sensitizer, etc. is applied or coated onto a substrate, and active light such as ultraviolet rays is irradiated through a negative image. It is known that the above image can be developed on a substrate by polymerizing or crosslinking the areas exposed to light and making them insoluble in solvents, and eluting the areas not exposed to light. used in manufacturing.

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, and therefore the types of processing solutions for etching, plating, etc. are limited. Furthermore, it is weak to organic solvents such as toluene, trichlene, and 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 systems have a short pot life at room temperature, require high temperatures and long periods of time to cure, and do not damage the substrate. This may cause warping or 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. Although attempts are being made to accelerate curing, the curing is insufficient under normal conditions, and the soldering heat resistance, solvent resistance, and alkali resistance are weak, and the cold/heat cycling properties are not sufficient, and it is difficult to make it flame retardant. No effort has been made. Also Tokukaisho
Publication No. 53-56018 proposes that flame retardancy be imparted by using a copolymer containing acrylonitrile as a binder and containing 5% or more of halogen in the composition, but the binder does not participate in crosslinking. As a result, the crosslinking density is low and various properties of the solder resist are unsatisfactory.

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

(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; (c) a halogenated compound. An epoxy resin prepolymer having a bisphenol A or novolac skeleton and at least two epoxy groups, and (d) a linear polymer compound polymerized using as one component a compound represented by the following general formula, [R ₁ is a group selected from hydrogen, methyl, and halogen, and 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. an aliphatic hydrocarbon group containing a group selected from the group consisting of a group selected from the group consisting of an aliphatic hydrocarbon group, and the others being an aliphatic hydrocarbon group or an aromatic hydrocarbon group. 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 at least two" means a compound having only one terminal ethylene group in the system, or a compound having three or more terminal ethylene groups, and a compound having an average terminal ethylene group of one as a whole. at least 2 per hit
It means owning oneself.

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

The sensitizer (b) in the present invention is one that initiates polymerization of the unsaturated compound upon irradiation with actinic light, and may also contain a main sensitizer and a secondary sensitizer that increases the action of the main sensitizer. A combination of sensitizers may be used.

As the sensitizer (b), conventionally used sensitizers can be used, but phenylketone-based sensitizers are particularly 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, 2-ethyl anthraquinone, 2
-t-butyl-anthraquinone, 2-aminoanthraquinone and the like.

The above sensitizer (b) has a similar effect,
By combining materials with different active light absorption ranges, polymerization initiation efficiency can be improved and exposure time can be further shortened. Particularly suitable is a mixture of benzophenone and Michler-Kent. The amount of this component used is 0.01 to 15% by weight, preferably 0.1 to 10% by weight in the photosensitive resin composition.

The compound (c) in the present invention is an epoxy resin prepolymer having a halogenated bisphenol A or novolak skeleton and at least two epoxy groups, and the halogen is
Examples include bromine, chlorine, etc., and bromine is particularly preferably used. Further, a halogenation rate of 5 to 80% by weight is preferable because it provides an excellent flame retardant effect. Examples of the above-mentioned epoxy resin prepolymers include diepoxy ether of monobromobisphenol A, diepoxy ether of tetrabromobisphenol A, and more specific examples include Epicote
1045, 1046, 1050 (all Ciel company product names),
Examples include Araldite 8011, 8024, and 8049 (all Ciba Geigy product names).

These compounds (c) are used alone or in combination, and the amount used is 5 to 80% in the photosensitive resin composition.
% by weight, preferably 15-70% by weight.

Here, several methods are known for making a photosensitive resin composition flame retardant. One method is to add antimony oxide as a flame retardant to the composition, but although a high level of flame retardation can be achieved, some of the properties of the composition are deteriorated. Therefore, it is necessary to reduce the amount of antimony oxide added or to eliminate it completely. Therefore, in the present invention, the compound (c) component is used in order to meet the flame retardant standards and avoid the adverse effects that occur when antimony oxide is added.

Conventional latent curing agents include boron trifluoride monoethylamine, boron trifluoride benzylamine complex, tetrafluoroborate, adipic acid, dihydrazide, triethylaminoporan, phenylenediamine-zinc bromide complex, dicyandiamide, etc. However, the visible time at room temperature is too short, making storage impossible.

As a latent curing agent with a long visible time at room temperature, p,
p'-diaminodiphenylmethane, p,p'-diaminodiphenyl sulfonic acid, 2-ethyl-4-ethylimidazole, etc. have also been found, but they require high temperatures and long periods of time to cure, causing the substrate to warp. The processing time is unfavorable.

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

As a result of extensive research, the present inventors have discovered a linear polymer compound (d) that is polymerized using a compound (d-1) represented by the following general formula as one component.

[R ₁ is a group selected from hydrogen, methyl, and halogen,
At least one of R ₂ , R ₃ , and R ₄ is a hydroxyl group, an alkoxyl group, or an allyl group.
An aliphatic hydrocarbon group containing a group selected from the group consisting of an oxy group, an acryloyloxy group, and a methacryloyloxy group, and the others are aliphatic hydrocarbon groups or aromatic hydrocarbon groups.] The above linear polymer Compound (d) acts as a latent curing agent, has a sufficiently long pot life at room temperature as a photosensitive resin composition, and has excellent durability when cured at an appropriate temperature and in a short time to form a permanent protective film. This provides solvent resistance, alkali resistance, and soldering heat resistance.

In the compound (d-1) of the above general formula (), the number of carbon atoms in the aliphatic hydrocarbons of R ₂ , R ₃ , and R ₄ is preferably 6 or less, since the smaller the number of carbon atoms, the better the heat resistance. It may also contain a double bond.

These reasons are not clear, but the general formula ()
It is considered that the compound (d-1) has appropriate polarity to be uniformly dispersed in the photosensitive resin composition and will not bleed out and adversely affect the substrate surface. or
When R ₂ , R ₃ , and R ₄ contain double bonds, they are assumed to be incorporated into the polymerization system upon irradiation with actinic light, and to have a favorable effect on the dispersibility and curing of compound (c).

As the compound (d-1) represented by the general formula (), for example, 1,1-dimethyl-1-(2-
Hydroxy-3-butoxypropyl)amine-methacrylimide, 1,1-dimethyl-(2-hydroxy-3-acryloxypropyl)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 (d) can be obtained by polymerizing the above compound (d-1) to oligomerize and increase the molecular weight by a conventional method, or preferably by copolymerizing it with other polymerizable monomers. Compound (d-1)
When polymerizing alone, the molecular weight is preferably in the range of 1,000 to 20,000, and the amount used is preferably 1 to 30% by weight in the photosensitive resin composition.

Other polymerizable monomers to be copolymerized with compound (d-1) include methyl (meth)acrylate,
Butyl (meth)acrylate, styrene, maleic anhydride, etc. can be used. When these polymerizable monomers are copolymerized to have a high molecular weight, they can be used as film-forming binders as they are, and when a compound such as polymethyl methacrylate is used as a binder, monomers and compounds common to the binder (d-1 ), it is possible to prepare a composition that has good compatibility and does not bleed out.

When compound (d-1) is copolymerized with another polymerizable monomer, it is preferable that compound (d-1) be contained in a range of 1 to 15% by weight and that its molecular weight be in a range of 100,000 to 300,000. The amount of linear polymer compound (d) used at this time is in the range of 10 to 90% by weight, preferably 30 to 60% by weight.

The linear polymer compound (d) described above can rapidly harden compound (c) in a short time of 10 to 30 minutes at about 150℃, and has excellent alkali resistance, as well as excellent solvent resistance and Solder heat resistance is improved. Furthermore, the linear polymer compound (d) significantly improves the storage stability at room temperature, and the curability of the compound (c) at high temperatures is good. This means that the compound (d-1) moiety represented by the general formula () in the linear polymer compound (d) is appropriately retained,
It seems to suppress the curing of epoxy at room temperature.

In addition, the linear polymer compound (d-1) does not cause adverse effects on the substrate surface due to bleed-out, such as electrical properties, as seen with general latent curing agents, and does not cause any adverse effects on the substrate-resist surface due to repeated cooling and heating. This has the effect of preventing peeling and cracking at the interface.

In addition to the above-mentioned essential components, the photosensitive resin composition of the present invention can contain secondary components for various purposes. That is, plasticizers, adhesion improvers, dyes, pigments, and other fillers for improving storage stability.

(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 light, and is sufficiently thermally stable at temperatures below 80°C. A permanent protective coating can be formed using conventional methods.

That is, the photosensitive resin composition of the present invention is usually 3 to 60
Adjust the solution by dissolving it in an organic solvent such as methyl ethyl ketone, toluene, methyl cellosolve, or chloroform to a concentration of % 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 active light such as ultraviolet rays through a negative mask, and the exposed areas are cured by photopolymerization and crosslinking. Then 1, 1, 1
- Use trichloroethane, etc. to elute the unexposed area and perform the phenomenon. 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 it also
By heating and curing in a short period of time, it becomes a permanent protective film with excellent heat resistance and mechanical strength. This protective film is not attacked by aromatic hydrocarbons such as toluene, ketone solvents such as methyl ethyl ketone, and halogenated hydrocarbon solvents such as methylene dichloride.
Fully resistant to strong acids and aqueous alkaline solutions.

Therefore, it can be used as a permanent protective film such as a solder resist with excellent soldering heat resistance. still,
A protective film with excellent strength can also be formed by post-exposure to ultraviolet light or the like at an intensity of 1 to 3 J/cm ² prior to heat curing.

Furthermore, 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. Note that parts mean parts by weight.

Example 1 Methyl methacrylate/1,1-dimethyl-1-
(2-hydroxy-3-butoxypropyl) amine-methacrylimide (90/10) copolymer (weight average molecular weight 200,000) 30 parts pentaerythritol triacrylate 30 parts diepoxy ether of monopromobisphenol A (halogen content 12%) 30 parts benzophenone 3 parts Michler's ketone 0.5 part p-methoxyphenol 0.5 part The above was dissolved in 200 parts of methyl ethyl ketone to prepare a photosensitive composition. When this was subjected to a storage test at 40°C, it was confirmed that it had sufficient light and heat curing properties even if left for more than 6 months.

In addition, five test strips prepared from a solution were tested at 150°C for 20
When heated for 1 minute and a combustion test conducted, the average combustion time was within 10 seconds after each of the first and second ignitions.

The photosensitive resin composition obtained with the above formulation was applied and dried on polyethylene terephthalate with a thickness of 25 μm to form a photosensitive layer with a thickness of 50 μm. 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 20 minutes, and a protective film with a precise image corresponding to a negative mask was obtained. This protective coating consists of methyl ethyl ketone, acetone, chloroform, trichlene, methanol, 10% aqueous sulfuric acid, toluene,
There was no change when immersed in xylene for 1 day, and no abnormality was observed even when immersed in a sodium hydroxide aqueous solution of pH 12 at 70°C for 1 day.

Also, heat and cool to -65℃ and 125℃ for 100 minutes at intervals of 60 minutes.
There was no change even after repeating the test several times and further immersing it in a solder bath at 260 to 270°C for 2 hours.

Example 2 Methyl methacrylate/1,1-dimethyl-1-
(2-hydroxy-3-butoxypropyl) amine-methacrylate imide (90/10) copolymer (weight average molecular weight 200,000) 30 parts pentaerythritol triacrylate 30 parts diepoxy ether of tetrapromobisphenol A (halogen content 46-50%) [Product name: Araldite 8049, Ciba Geigy] 30 parts benzophenone 3 parts Michler's ketone 0.5 part p-methoxyphenol 0.5 part The above was dissolved in 200 parts of methyl ethyl ketone to prepare a photosensitive composition. When this was subjected to a storage test at 40°C, it was confirmed that it had sufficient light and heat curing properties even if left for more than 6 months.

In a UL test, five test strips prepared from a solution were heated at 150°C for 20 minutes and burned, with an average burn time of 1.4 seconds after each of the first and second ignitions. It was hot.

Other properties were the same as in Example 1.

Comparative example 1 Methyl methacrylate/1,1-dimethyl-1-
(2-Hydroxy-3-butoxypropyl) amine-methacrylate imide (90/10) copolymer (weight average degree of polymerization 200,000) 30 parts Pentaerythritol triacrylate 30 parts Epoxy resin [Product name: Epicote 828 Ciel Co.] 30 Part benzophenone 3 parts Michler's ketone 0.5 part p-methoxyphenol 0.5 part The above was dissolved in 200 parts of methyl ethyl to prepare a photosensitive resin composition.

In a UL test, five test strips prepared from a solution were heated at 150°C for 20 minutes and burned for more than 30 seconds after each first and second ignition.

Comparative Example 2 Trimethylolpropane triacrylate 25 parts Di-(3-acryloxy-2-hydroxypropyl) ester of tetrapromobisphenol A (halogen content 50%) 40 parts Benzophenone 6 parts Michler's ketone 0.5 parts Polymethyl meth Acrylate 10 parts Methyl methacrylate-acrylonitrile-butadiene-styrene (46/9/14/31) copolymer
33 parts methylene chloride 150 parts The photosensitive resin prepared from the above is 260~
When immersed in a 270°C solder bath for 2 minutes, it melted and separated from the laminated copper plates.

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

Claims (1)

[Scope of Claims] 1 (a) Substantially at least 2 terminal ethylene groups
(b) a photopolymerizable sensitizer; (c) an epoxy resin prepolymer having a halogenated bisphenol A or novolak skeleton and at least two epoxy groups; d) A linear polymer compound polymerized using a compound represented by the following general formula () as one component, ((R ₁ is a group selected from hydrogen, methyl, ethyl, halogen, at least one of R ₂ , R ₃ and R ₄
One is a hydroxyl group and an alkoxyl group,
An aliphatic hydrocarbon group containing a group selected from the group consisting of an allyloxy group, an acryloyloxy group, and a methacryloyloxy group; the others are aliphatic hydrocarbon groups or aromatic hydrocarbon groups. Or a photosensitive resin composition characterized by having these as main components.