JPH04356051A - Photosensitive thermosetting resin composition and method of pattern forming - Google Patents

Abstract

PURPOSE:To provide a photosensitive thermosetting resin compsn. suitable for the production of printed circuit boards and the like and to offer the formation method of patterns. CONSTITUTION:The photosensitive thermosetting resin compsn. contains the following components (a)-(d) as essential components. (a) Photosensitive oligomers obtd. by effecting the reaction of alpha,beta-unsatd. monocarboxylic acid ester having alcohol type hydroxyl groups expressed by formula I with polymers and/or copolymers obtd. by adding alpha,beta-unsatd. dicarboxylic acid anhydride to polymers and/or copolymers of conjugated dienes having 500-5000 number average mol.wt. so that at least >=80mol% of the acid anhydride group of the additional compd. is subjected to open-ring reaction. (b) photopolymn. initiator, (c) epoxy resin having two or more epoxy groups in the molecule, and (d) 2,4- diamino-6-vinyl-S-triazine. In formula I, R<1> and R<2> are hydrogen atom or org. residues of 1-6 carbon number, R<3> is an alkylene group of 2-12 carbon number.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a novel photosensitive thermosetting resin composition and a pattern forming method, which are used in the manufacture of printed wiring boards and precision processing of metals, and which are particularly useful as solder resists for printed wiring boards. Regarding. More specifically, 1) high photocuring reactivity and high resolution, 2) good developability, 3) long pot life, 4) excellent adhesion, 5) excellent electrical insulation and corrosion resistance, 6) excellent 7) Non-whitening property against water-soluble flux for leveler, 8
) excellent resistance to solvents such as methylene chloride, 9)
Excellent acid and alkali resistance, 10) Excellent plating resistance, 11) Excellent PCT (Pressure Cook)
The present invention relates to a photosensitive thermosetting resin composition for a solder resist that has all the characteristics such as test properties, and a method for forming a solder resist pattern.

0002

2. Description of the Related Art Solder resist is a material that is coated when electronic components are soldered onto a printed wiring board in order to prevent solder from adhering to areas other than the soldered areas and at the same time to protect wiring circuits. Therefore, it has excellent soldering heat resistance, water-soluble flux resistance, electrical insulation, adhesion,
Good PCT characteristics etc. are required. Further, solder resists are often used as they are as plating resists, and in that case, alkali resistance, acid resistance, plating resistance, etc. are required.

As solder resists, epoxy-based thermosetting inks are mainstream for industrial printed circuit boards, and ultraviolet thermosetting inks are mainstream for consumer printed circuit boards. Screen printing has traditionally been the main method used to form solder resist films, but screen printing has the problem of not being able to ensure sufficient precision of the resist pattern, and as electronic devices have become lighter, thinner, and smaller, printed wiring boards have become increasingly popular. The current situation is that it is unable to cope with the increasing density of electronic devices and the surface mounting of small components.

In order to solve this problem, a dry film type solder resist in which the resist is in the form of a photosensitive film has been developed and put into practical use. Although it is possible to obtain a highly accurate resist pattern with dry film, on the other hand,
There is a problem that the embedding of the resist between the wiring circuits is poor.

[0005] In order to solve this problem, a liquid photosensitive solder resist has been proposed. Some examples of this type are shown below.

British Patent Application Publication GB-2032939A
The publication describes a photopolymerizable coating composition comprising a reaction product of a polyepoxy compound and an ethylenically unsaturated carboxylic acid, an inorganic filler, a photopolymerization initiator, a volatile organic solvent, and the like. This is an example of only photocuring, and since it does not have sufficient soldering heat resistance, we created a highly accurate pattern using a photosensitive resin such as the one shown below, and added thermosetting properties to it. The idea of improving heat resistance is becoming popular.

[0007] As an example, Japanese Patent Laid-Open No. 60-208377
The publication describes a reaction product of a phenol novolac type epoxy resin and an unsaturated monobasic acid, a partial reaction product of a cresol novolac type epoxy resin and an unsaturated monobasic acid, a photopolymerization initiator, an organic solvent, and an amine thermosetting agent. A solder resist consisting of etc. is described. This is because the partially reacted product of the cresol novolac type epoxy resin and the unsaturated monobasic acid has residual epoxy groups, so heat curing is performed with the idea of crosslinking these with an amine thermosetting agent.

[0008] Further, as an example of using an epoxy resin as a thermosetting component, JP-A-61-243869 discloses a product in which a reaction product of a novolac type epoxy resin and an unsaturated monocarboxylic acid is reacted with a polybasic acid. A method is disclosed in which an epoxy resin is used in combination with a photosensitive component consisting of a photopolymerization initiator, a diluent, and the like.

Furthermore, JP-A-2-99504 discloses a photosensitive thermosetting resin in which an epoxy resin is used in combination with a special photosensitive component, which is a reaction product of a maleated butadiene polymer and a hydroxyalkyl (meth)acrylate. Compositions are disclosed by the inventors.

As described above, several attempts have been made to improve soldering heat resistance, adhesion, chemical resistance, plating resistance, etc. by blending a thermosetting epoxy resin with a photosensitive component. It has been pointed out that when the ratio of epoxy resin is increased, the photocuring reactivity decreases, and the developability of unexposed areas decreases, making it difficult to form a good resist pattern, as well as disadvantages such as poor plating resistance.

[0011]

[Problems to be Solved by the Invention] As mentioned above, various material systems have been proposed as solder resists, but the properties required for solder resists include good adhesion, soldering heat resistance, and electrical insulation. Recently, as electronics equipment has become lighter, thinner, and smaller, the density of printed wiring boards has increased and small parts have become surface-mounted.In addition to being able to form more detailed patterns, 1) high light Curing reactivity and high resolution, 2) Good developability, 3) Long pot life, 4) Excellent adhesion, 5) Excellent electrical insulation and corrosion resistance, 6) Excellent soldering heat resistance, 7) Leveler Non-whitening property for water-soluble flux, 8
) excellent resistance to solvents such as methylene chloride, 9)
Excellent acid and alkali resistance, 10) Excellent plating resistance, 11) Excellent PCT (Pressure Cook T)
There is a growing demand for materials for solder resists and methods for forming solder resist patterns that have all the characteristics such as est) properties, etc.

Epoxy-based and epoxy-melamine-based thermosetting screen printing inks have the fatal drawback that it is difficult to form fine patterns, and the former has poor plating resistance, while the latter has poor soldering heat resistance. There are problems with chemical resistance and plating resistance. Although ultraviolet thermosetting screen printing inks can easily form fine patterns, they have problems with soldering heat resistance, chemical resistance, plating resistance, and the like.

Although it is possible to obtain a highly accurate resist pattern with a dry film type solder resist, it not only has insufficient soldering heat resistance, adhesion, chemical resistance, plating resistance, etc., but also has poor resistance between wiring circuits. There is a problem of poor resist embedding.

With liquid photosensitive solder resist, it is possible to obtain a highly accurate resist pattern, and the resist has good embedding properties between wiring circuits, but on the other hand, it has poor soldering heat resistance, adhesion, chemical resistance, plating resistance, etc. The problem is that it is insufficient. The liquid photosensitive solder resist is blended with a thermosetting epoxy resin to improve soldering heat resistance and adhesion.
Attempts have been made to improve chemical resistance, plating resistance, etc., but in this case, increasing the ratio of epoxy resin improves heat resistance, adhesion, etc., but decreases photocuring reactivity and causes unexposed areas to deteriorate. There is a drawback that developability is reduced and it is difficult to form a good resist pattern. Furthermore, although epoxy resins generally have good alkali resistance, they have poor acid resistance, so they have the disadvantage of low resistance to plating solutions in acidic baths. for example,
Electroless nickel plating solution and electroless gold plating solution have a pH of 4~
Since it is an acid bath of No. 5 and is immersed at 90° C. for 15 to 30 minutes, sufficient chemical resistance is required as a plating-resistant resist. Furthermore, as hydrogen gas is generated in the metal deposits during the plating process, the plating solution may enter the interface between the solder resist and the electrodes of the printed wiring board, creating a force that peels off the solder resist. Strong adhesion to the base material is required.

A photosensitive thermosetting liquid resist using a reaction product of myrenated polybutadiene and hydroxyalkyl (meth)acrylate described in JP-A-2-99504 is a conventional novolak type epoxy resin and an unsaturated monocarboxylic resin. Although it has superior plating resistance and chemical resistance compared to the product obtained by reacting the reaction product with an acid with a polybasic acid, it has not yet achieved sufficient performance.

The object of the present invention is to provide a photosensitive thermosetting resin composition which is free from the various drawbacks mentioned above, has excellent photosensitivity and developability, and has a long pot life.

Furthermore, in addition to the above-mentioned excellent properties, the present invention also provides adhesive properties required for solder resists, electrical insulation and galvanic corrosion resistance, soldering heat resistance, non-whitening property against water-soluble flux for leveler, and chloride resistance. A photosensitive thermosetting film that produces cured coatings with excellent resistance to solvents such as methylene, acid and alkali resistance, plating resistance, PCT properties, etc., and is suitable for manufacturing consumer and industrial printed wiring boards, etc. The object of the present invention is to provide a synthetic resin composition and a method for forming a pattern.

[0018]

[Means for Solving the Problems] As a result of various studies to solve these problems, the present inventors have solved the above problems by adding a specific compound to a specific photosensitive thermosetting resin composition. We have succeeded in satisfying all of these requirements and have completed the present invention.

That is, the present invention provides (a) an acid anhydride obtained by adding an α,β-unsaturated dicarboxylic acid anhydride to a conjugated diene polymer and/or copolymer having a number average molecular weight of 500 to 5,000; Polymers and/or copolymers of conjugated dienes containing physical groups have

[0020]

[C5]

[In the formula, R1 and R2 are hydrogen atoms or organic residues having 1 to 6 carbon atoms, and R3 is an organic residue having 2 to 12 carbon atoms.
A photosensitizer obtained by reacting an α,β-unsaturated monocarboxylic acid ester having an alcoholic hydroxyl group represented by the alkylene group of (b) a photopolymerization initiator, (c) an epoxy resin having two or more epoxy groups in the molecule, and (d) 2,4-diamino-6-vinyl-S-triazine and/or 2, 4-diamino-
The present invention relates to a photosensitive thermosetting resin composition containing 6-methacryloyloxyethyl-S-triazine as an essential component.

Furthermore, the present invention provides a method of applying the photosensitive thermosetting resin composition to a printed wiring board, exposing it to light through a photomask, developing the unexposed areas to form a pattern, and then thermosetting the composition. The present invention relates to a method of forming a solder resist pattern.

Each component of the photosensitive thermosetting resin composition of the present invention will be explained below.

The photosensitive oligomer of component (a) is as follows:
A conjugated diene polymer and/or copolymer containing an acid anhydride group obtained by adding α,β-unsaturated dicarboxylic acid anhydride to a conjugated diene polymer and/or copolymer having a number average molecular weight of 500 to 5000 In the copolymer, the general formula

0025
]

[C6]

[In the formula, R1 and R2 are hydrogen atoms or organic residues having 1 to 6 carbon atoms, and R3 is a hydrogen atom or an organic residue having 2 to 12 carbon atoms.
α,β-unsaturated monocarboxylic acid ester (A
), or α,β-unsaturated monocarboxylic acid ester (A
) and an alcohol represented by the general formula (B) R4 -OH [wherein R4 represents an organic residue having 1 to 20 carbon atoms] is reacted, and at least 80 of the acid anhydride groups of the adduct are reacted. The one obtained by ring-opening the mole % is used.

The conjugated diene polymer and/or copolymer used herein refers to a low polymer of a conjugated diolefin having 4 to 5 carbon atoms such as butadiene or isoprene, or one or more of these conjugated diolefins. and low polymerization degree copolymerization with monomers other than these conjugated diolefins having ethylenically unsaturated double bonds, especially aliphatic or aromatic monomers such as isobutylene, styrene, α-methylstyrene, vinyltoluene, divinyltoluene. It is a combination. A mixture of two or more of these can also be used.

The number average molecular weight of the conjugated diene polymer and/or copolymer is preferably in the range of 500 to 5,000. If the molecular weight is less than 500, the coating film strength after photocuring will not be sufficient, and if it exceeds 5,000, the smoothness of the coating will deteriorate, so both are not preferred.

These low polymers are produced by conventionally known methods. That is, a conjugated diolefin having 4 to 5 carbon atoms alone, a mixture of these conjugated diolefins, or preferably 50 mol% based on the conjugated diolefin using an alkali metal or an organic alkali metal compound as a catalyst.
It can be produced by anionically polymerizing the following amounts of aromatic vinyl monomers at a temperature of 0 to 100°C. In this case, in order to control the molecular weight and obtain a light-colored low polymer with a low gel content, an organic alkali metal compound such as sodium benzyl is used as a catalyst, and a compound having an alkylaryl group, such as toluene, is chained. A chain transfer polymerization method using a transfer agent (Japanese Patent Publication No. 54-15586), a living polymerization method using a polycyclic aromatic compound such as naphthalene as an activator and an alkali metal such as sodium as a catalyst in a tetrahydrofuran solvent (Japanese Patent Publication No. 54-15586) 43-27432
Polymerization method using an aromatic hydrocarbon such as toluene or xylene as a solvent, using a dispersion of an alkali metal such as sodium as a catalyst, and controlling the molecular weight by adding an ether such as dioxane (Japanese Patent Publication No. 32-7446) Publication No., Special Publication No. 1973
-10188, Japanese Patent Publication No. 38-1245) or a coordination anion polymerization method using an acetylacetonate compound of a group 8 metal such as cobalt or nickel and an alkyl aluminum halide (Japanese Patent Publication No. 45-507)
Methods such as those disclosed in Japanese Patent Publication No. 46-80300 are preferred.

By adding α,β-unsaturated dicarboxylic acid anhydride to these conjugated diene polymers and/or copolymers, an acid anhydride group adduct can be produced.

The α,β-unsaturated dicarboxylic acid anhydride used in the present invention includes maleic anhydride, citraconic anhydride, chloromaleic anhydride and the like.

[0032] This addition reaction is carried out in an inert solvent that dissolves either one or both of these at a reaction rate of 100 to 2.
It is carried out at a temperature of 20°C. At this time, it is desirable to add 0.1 to 0.5 polymerization portion of hydroquinone, catechols, p-phenylenediamine derivatives, etc. as a gelling inhibitor.

In the present invention, α,
It is desirable to add a β-unsaturated dicarboxylic acid anhydride. This softening point is mainly determined by the unsaturated bond content and molecular weight of the raw material conjugated diene polymer or copolymer, α, β-
It depends on the amount of unsaturated dicarboxylic anhydride added. For example, when a liquid butadiene polymer with a number average molecular weight of 1000 is used, a total acid value of 400 or more is required.

If the softening point is lower than this, the final product, the reaction product with the α,β-unsaturated monocarboxylic acid ester having a hydroxyl group, will remain sticky and the photomask will stick to the coating film during photocuring. Because it is stored away, contact exposure with the photomask is not possible.

Next, α,β-unsaturated monocarboxylic acid ester (A
), or α,β-unsaturated monocarboxylic acid ester (A
) and alcohol (B) to open at least 80% of the acid anhydride groups of the adduct to produce a photosensitive oligomer.

Here, the α,β-unsaturated monocarboxylic acid ester having an alcoholic hydroxyl group represented by formula (A) is specifically, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,
Examples include 2-hydroxypropyl acrylate and 2-hydroxy-3-phenoxypropyl acrylate, and these can be used alone or in combination.

Specific examples of the alcohol (B) include ethyl alcohol, butyl alcohol, ethyl cellosolve, butyl cellosolve, cyclohexanol, benzyl alcohol, and phenol.

In this ring-opening reaction, the ester (A) having a photosensitive double bond is essential, and the ratio of the α,β-unsaturated monocarboxylic acid ester (A) to the alcohol (B) is determined by the molar ratio. (A):(B)=1:0-4, preferably (A):(B)=1:0-1. Alcohol (B) is used to control the adhesiveness or solubility of the resist coating, but if the amount of α,β-unsaturated monocarboxylic acid ester (A) added is less than this range, fine wiring will be formed. become unable.

The ring-opening reaction of the acid anhydride group by these is usually carried out in the presence of a base catalyst at a temperature of 100°C or lower, for example 50 to 100°C.
It is carried out at a relatively low temperature. It is appropriate that the ring-opening ratio be 80 mol% or more, preferably 90 mol% or more of the acid anhydride groups, from the viewpoint of photocurability and long-term stability of the coating film. The ring-opening reaction is preferably carried out in the presence of a solvent. As the solvent, it is preferable to use a solvent that has no reactivity with these and can dissolve both. Examples include aromatic hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as 2-methoxypropyl acetate and ethyl acetate, ethers such as diethylene glycol dimethyl ether and triethylene glycol dimethyl ether, and Examples include tertiary alcohols such as diacetone alcohol. In this way, the photosensitive oligomer described above is produced.

It is also possible to use an oligomer in which a portion of the remaining acid anhydride groups of this photosensitive oligomer is further imidized with a primary amine, or a portion of the carboxylic acid group of this photosensitive oligomer is previously esterified with a monoepoxy compound. Can be done.

In the photosensitive thermosetting resin composition of the present invention, a photosensitive monomer can be added as required. Examples of photosensitive monomers include 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, 2-hydroxyethyl methacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate. Known photopolymerizable monomers such as erythritol trimethacrylate can be used. The amount of the photosensitive monomer added is in the range of 0 to 20 parts by weight per 100 parts by weight of the photosensitive oligomer, and is selected within a range that does not give tack to the coating film.

As the photopolymerization initiator for component (b) of the present invention, conventionally known ones can be used. For example, in addition to bayzoin, benzoin methyl ether, benzyl, Michler's ketone, diethylthioxanthone, etc., Irgacure-184, Irgacure-651, Irgacure-907 (manufactured by Ciba Geigy), Darocure-1
Examples include photopolymerization initiators commercially available under trade names such as 173 (manufactured by Merck & Co.). The amount of these used is usually in the range of 1 to 15 parts by weight per 100 parts by weight of the photosensitive oligomer. If this amount is less than 1 part by weight, the photocurability will decrease, and if it is more than 15 parts by weight, the strength of the photosensitive coating will decrease, which is not preferable.

As the epoxy resin having two or more epoxy groups in the molecule used as the thermosetting component (c) of the present invention, any of the following epoxy resins can be used.

1) Glycidyl ether epoxy resin a
) Bisphenol A type epoxy resin and its derivatives b
) Bisphenol F type epoxy resin c) Bisphenol S type epoxy resin d) Bisphenol type special epoxy resin e) Novolac type epoxy resin e-1) Phenol novolac type epoxy resin e-2)
Cresol novolac type epoxy resin e-3) Special novolac type epoxy resin f) Biphenyl type epoxy resin g) Special glycidyl ether type epoxy resin 2) Special epoxy resin h) Glycidyl ester type epoxy resin i) Glycidylamine type epoxy resin j) Ring Formula aliphatic epoxy resin k) Heterocyclic epoxy resin k-1) Hydantoin type epoxy resin k-2) Triglycidyl isocyanurate

[0045]
Among these epoxy resins, preferred are phenol novolac type epoxy resins, such as Epiclon EXA-4506 manufactured by Dainippon Ink and Chemicals; cresol novolac epoxy resins, such as Epiclon N-695 and EXA- manufactured by Dainippon Ink and Chemicals. 4621, etc.; special novolak type epoxy resins, such as Epiclon N-510 manufactured by Dainippon Ink and Chemicals; biphenyl type epoxy resins, such as YX-4000 manufactured by Yuka Shell Epoxy; special glycidyl ether type epoxy resins, such as Nipponka. EPPN-500 series manufactured by Yakusha, Epiclon HP-4032 manufactured by Dainippon Ink & Chemicals, etc.; and triglycidyl isocyanurate of a heterocyclic epoxy resin are preferably used, but the following formulas (I), (II) and (I
It is most preferable to use one or more epoxy resins selected from the group consisting of II).

[0046]

[C7]

YX-4000 (manufactured by Yuka Shell Epoxy Co., Ltd.)

[0048]

[Chemical formula 8]

EPPN-500 series (manufactured by Nippon Kayaku Co., Ltd., non-novolac type polyfunctional epoxy resin) EPPN-
501H, EPPN-502H, EOCN-1020,

[0050]

[Chemical formula 9]

Epiclon N-510 (manufactured by Dainippon Ink Chemical Co., Ltd., modified novolak type polyfunctional epoxy resin) [In each formula, G represents a glycidyl group]

[0052]
In particular, specific epoxy resins of formulas (I) to (III) may be used alone or in combination, or other epoxy resins (bisphenol A type epoxy resin and its derivatives, bisphenol F type epoxy resin, bisphenol S photosensitive epoxy resin, bisphenol type special epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, cycloaliphatic epoxy resin, hydantoin type epoxy resin, heterocyclic epoxy resin, etc.). A photosensitive thermosetting resin composition with excellent properties and developability, and a long pot life.It has the adhesion required for solder resists, electrical insulation and corrosion resistance, soldering heat resistance, and non-whitening for water-soluble flux for levelers. It produces a cured coating film with excellent properties such as hardness, excellent resistance to solvents such as methylene chloride, acid and alkali resistance, plating resistance, and PCT properties, making it suitable for the production of consumer and industrial printed wiring boards, etc. The present invention can provide a thermosetting resin composition and a method for forming a solder resist pattern.

The amount of these epoxy resins added varies depending on the type of epoxy resin used, but is preferably in the range of 20 to 145 parts by weight per 100 parts by weight of the photosensitive oligomer. If it is below or exceeds this range, the heat resistance is low and P
Poor CT properties, electrical insulation properties, and electrolytic corrosion resistance.

As component (d) of the present invention, 2,4-diamino-6-vinyl-S-triazine and 2,4-diamino-6-methacryloyloxyethyl-S-triazine are used. Heat resistance and plating resistance are insufficient simply by combining the photosensitive component (a) and the epoxy resin (c), but these performances are significantly improved only when the specific compounds listed above are blended. do. The amount of these additives is usually in the range of 1 to 10 parts by weight per 100 parts by weight of the photosensitive oligomer. If this amount is less than 1 part by weight, the plating resistance will not be sufficient, and if it is more than 10 parts by weight, the curing will be saturated, so it is not necessary.

Fillers can be added to the photosensitive thermosetting resin composition of the present invention. Known fillers include talc, quartz, alumina, barium sulfate, and the like. The amount of these additions is 100% of the photosensitive oligomer.
It ranges from 0 to 150 parts by weight. Also,
Phthalocyanine blue, cyanine green, as required
Colored pigments such as Hansa Yellow, various fluorescent pigments, and fine particles for thixotropic control such as Erosil are also included.

The photosensitive thermosetting resin composition of the present invention is diluted with an organic solvent if necessary, mixed and polished, and the viscosity at room temperature is adjusted to 1 to 500 poise to form an ink. As the organic solvent used here, commonly used diacetone alcohol, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, solphytoacetate, propylene glycol monomethyl acetate, diglyme, etc. are used. The viscosity varies depending on the application method, and is generally in the range of 1 to 100 poise for electrostatic coating, and 100 to 500 poise for screen printing or curtain coating. Since this resin composition has photosensitivity, it is possible to form a pattern by exposing the coating film to light through a photomask, and furthermore, after the pattern formation, the coating film can be further cured by heat. It is a thermosetting resin composition.

The photosensitive thermosetting resin composition of the present invention is particularly preferably used as a solder resist.

To form a solder resist pattern using the photosensitive thermosetting resin composition of the present invention, first, the photosensitive thermosetting resin composition of the present invention is applied to a printed circuit board on which a conductive circuit is formed. Create a coating film by doing this.

[0059] Application to the substrate is usually carried out by methods such as screen printing, spray coating, and curtain coating. The coating film is dried by hot air drying, far infrared rays, etc., usually at a temperature of 120° C. or lower, preferably 60° C. to 100° C., for 10 to 60 minutes. The temperature and time at this time vary depending on the type of solvent used, dilution rate, coating thickness, etc., so it is necessary to select and set optimal conditions. However, if the curing temperature exceeds 120° C., a thermosetting reaction will start and a pattern will not be formed after exposure and development, which is not preferable.

The coating film thus obtained has no surface tackiness at room temperature and does not stick to the photomask even when it comes into contact with the photomask.

After drying, the film is exposed to ultraviolet rays by direct laser irradiation or by bringing the coating film into close contact with a negative type photomask using, for example, a mercury lamp, a xenon lamp, a metal halide lamp, or the like. Next, the unexposed areas are developed with an alkaline aqueous solution to form a pattern. When this photosensitive film is further thermally cured (after-cured), it becomes a highly reliable film with excellent heat resistance, adhesion, and good electrical insulation, making it extremely useful as a solder resist, plating resist, etc. As an alkaline developer, generally 1
An aqueous solution of about 5% by weight of sodium carbonate or the like can be used.

[0062] After-cure is usually carried out at 120 to 180°C for 10 to 60 minutes using hot air drying, far infrared rays, etc.
If the after-cure is insufficient, the physical properties of the coating film will not be sufficient, and if the coating is cured excessively, the coating film may deteriorate.

[0063]

[Action] As a photosensitive oligomer used as the main component of the photosensitive resin component, an α,β-unsaturated dicarboxylic acid anhydride adduct of a conjugated diene polymer and/or copolymer has an alcoholic hydroxyl group. -By employing an oligomer obtained by half-esterification with an unsaturated monocarboxylic acid ester, similar to the reaction product of a conventional novolac type epoxy resin and an unsaturated monocarboxylic acid with a polybasic acid, Not only can it be developed with an alkaline aqueous solution, but it also has the effect of producing a cured coating film with better chemical resistance than conventional ones.

In addition, 2,4-diamino-6-vinyl-S-triazine and/or 2,4-diamino-6-methacryloyloxyethyl-S-triazine may be used as a component of the photosensitive thermosetting resin composition. The addition has the effect of significantly improving plating resistance.

Furthermore, epoxy resins (I) to (III) having the above-mentioned specific structures are used as thermosetting resin components.
By using , heat resistance, chemical resistance, plating resistance, etc. are significantly improved.

[0066] By blending these components, a photosensitive thermosetting resin composition with excellent photosensitivity and developability and a long pot life can be provided, and it can provide the adhesion and electrical insulation required for solder resists. resistance and galvanic corrosion resistance,
A cured coating film with excellent solder heat resistance, non-whitening property against water-soluble flux for levelers, excellent resistance to solvents such as methylene chloride, acid and alkali resistance, plating resistance, PCT property, etc., is obtained, and is suitable for consumer and industrial use. It has become possible to provide a photosensitive thermosetting resin composition and a method for forming a solder resist pattern suitable for manufacturing printed wiring boards and the like.

[0067]

Effects of the Invention The photosensitive thermosetting resin composition of the present invention is of an ultraviolet curing type and can be developed with alkali, so it has good workability and can provide a highly accurate resist pattern. Furthermore, since it is a thermosetting type, it has excellent adhesion, electrical insulation and corrosion resistance, soldering heat resistance, non-whitening property for water-soluble flux for levelers, excellent resistance to solvents such as methylene chloride, acid and alkali resistance, and plating resistance. sex,
A cured coating film with even better PCT properties etc. can be obtained. Therefore, it can be used as a solder resist, an etching resist, and a plating resist suitable for manufacturing printed wiring boards for consumer use and industrial use.

[0068]

[Examples] The present invention will be explained in detail below using examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are based on weight unless otherwise specified.

Synthesis Example 1 A polymer obtained by polymerizing butadiene at 30°C using benzyl sodium as a catalyst in the presence of toluene as a chain transfer agent, with a number average molecular weight of 1000, a viscosity at 25°C of 13 poise, and a 1,2 bond of 65%. 258g liquid butadiene polymer
, 194 g of maleic anhydride, 10 g of triethylene glycol dimethyl ether, and 2 g of trimethylhydroquinone were placed in a 1-liter separable flask equipped with a reflux condenser and nitrogen blowing tube, and the mixture was heated at 190°C under a nitrogen stream.
The reaction was carried out for 5 hours. After the reaction, unreacted maleic anhydride,
Distilling off triethylene glycol dimethyl ether,
442 g of maleated butadiene polymer having a total acid value of 480 mg KOH/g was obtained. The softening point (ring and ball softening point JIS-K-2531-60) of this material was 129°C.

Obtained maleated butadiene polymer 30
0g, diethylene glycol dimethyl ether 189g
The mixture was placed in a 2 liter separable flask equipped with a reflux condenser and a nitrogen blowing tube and dissolved at 125°C. After dissolving,
After cooling to 65° C., 149.0 g of 2-hydroxyethyl acrylate and 0.6 g of hydroquinone were added, followed by 3 g of triethylamine to start half-esterification. Although the temperature in the system rose due to the reaction heat as triethylamine was added, the reaction was carried out for 3 hours while controlling the reaction temperature to 85°C, and 70w of 2-hydroxyethyl acrylate of maleated butadiene polymer was added.
A t% diethylene glycol dimethyl ether solution was obtained.

Synthesis Example 2 Using the maleated butadiene polymer synthesized in Synthesis Example 1 and having a total acid value of 480 mgKOH/g, a half-esterified product with 2-hydroxyethyl methacrylate was obtained as follows.

300 g of maleated butadiene polymer and 194 g of diethylene glycol dimethyl ether were placed in a 2-liter separable flask equipped with a reflux condenser.
Dissolved at °C. After dissolving, the mixture was cooled to 65° C., 167 g of 2-hydroxyethyl methacrylate and 0.6 g of hydroquinone were added, and then 6 g of triethylamine was added to start half-esterification. Although the temperature in the system rose due to the reaction heat with the addition of triethylamine, the reaction was carried out for 3 hours while controlling the reaction temperature to 95°C, and 70 wt% of 2-hydroxyethyl methacrylate in the maleated butadiene polymer was obtained. A diethylene glycol dimethyl ether solution was obtained.

Examples 1 to 3 and Comparative Examples 1 to 2 Table 1
Base ingredients 1 to 4 having the formulations shown in (unit: parts by weight) were prepared using a three-roll mill.

Additive 1 (manufactured by Yuka Shell Epoxy Co., Ltd., biphenyl type epoxy resin, YX-
4000 (60 parts) and 40 parts of propylene glycol monomethyl acetate) were added thereto to obtain photosensitive thermosetting resin compositions of Examples 1 to 3 and Comparative Examples 1 to 2.

[0075]

[Table 1]

1) 70% diethylene glycol dimethyl ether solution of the half-esterified maleated butadiene polymer synthesized in Synthesis Example 1 with 2-hydroxyethyl acrylate

2) 70% diethylene glycol dimethyl ether solution of the half-esterified maleated butadiene polymer synthesized in Synthesis Example 2 with 2-hydroxyethyl methacrylate

3) Ciba Geigy, 2-methyl-1
-[4-(methylthio)phenyl]-2-morpholinopropan-1-one

4) 2,4-diethylthioxanthone manufactured by Nippon Kayaku Co., Ltd.

5) 2,4-diamino-6-vinyl-s-triazine manufactured by Shikoku Kasei Kogyo Co., Ltd.

6) 2,4-diamino-6-methacryloyloxyethyl-s-triazine manufactured by Shikoku Kasei Kogyo Co., Ltd.

[
7) Silica manufactured by Nippon Aerosil Co., Ltd.

0083
]8) Silicone antifoaming agent manufactured by Toshiba Silicone Co., Ltd.

Each photosensitive thermosetting resin composition was applied to the entire surface of a glass/epoxy printed circuit board by screen printing to a dry film thickness of 20 μm, and dried in a hot air dryer at 75° C. for 30 minutes. .

Next, a negative pattern photomask was brought into close contact with this dried coating film, and exposed to light at 500 mJ/cm2 using a metal halide lamp exposure device manufactured by Oak Co., Ltd., followed by 1%
Using aqueous sodium carbonate solution (30℃) as a developer, 2kg/
Developed with a spray pressure of cm2, washed with water and dried (75℃,
30 minutes).

Further, a heat curing reaction was carried out for 30 minutes in a hot air circulation oven at 150°C.

Table 2 summarizes the characteristics of each cured photosensitive thermosetting resin composition thus prepared. Also,
The compositions of Examples 1 to 3 all had a good shelf life of one month or more, and also had good developability.

[0088]

[Table 2]

The test methods and evaluation criteria used in these Examples are as follows.

1) Put the ink-like photosensitive thermosetting resin composition (without adding epoxy resin) into a shelf-life plastic container, seal it tightly, and store it for 40 minutes.
It was stored in a constant temperature bath at ℃, and the viscosity was measured over time. The shelf life was defined as the time when the initial viscosity doubled.

2) Apply ink of a photosensitive thermosetting resin composition to a developable epoxy substrate by screen printing (about 20 μm in dry film thickness),
After drying at 75°C for 30 minutes, a photomask was brought into contact with the coating surface, exposed to light at 500 mJ/cm2 using a metal halide lamp exposure device manufactured by Oak Seisakusho, and 2 kg/cm2 using a 1% aqueous sodium carbonate solution as a developer. Developed with spray pressure for 1 minute, rinsed with water spray, and when dry, visually judged whether there was any falling off in the irradiated areas or whether ink remained in the non-irradiated areas.

3) Photocuring reactivity and resolution Apply ink of a photosensitive thermosetting resin composition to the thickness of two sheets of cellophane tape on an epoxy substrate, and after drying at 75°C for 30 minutes, ST
OUFFER's step tablet and Hitachi Chemical's resolution measurement test pattern No. 1 was brought into contact with the coating surface, exposed to light at 500 mJ/cm2 using a metal halide lamp exposure device manufactured by Oak Seisakusho, and then developed for 1 minute at a spray pressure of 2 kg/cm2 using a 1% aqueous solution of sodium carbonate as a developer. Washed with water spray and dried. Next, it was thermally cured for 30 minutes in a hot air circulation oven at 150°C.

The number of remaining steps of the pattern was read using a STOUFFER step tablet and used as a measure of photocuring reactivity (sensitivity). It is thought that the greater the number of stages, the faster the photocuring reaction. In addition, Hitachi Chemical's test pattern for resolution measurement No. The resolution was evaluated according to 1.

4) Apply ink of a photosensitive thermosetting resin composition to an adhesive epoxy substrate by screen printing (dry film thickness: approximately 20 μm),
After drying at 75°C for 30 minutes, a photomask was brought into contact with the coating surface, exposed to light at 500 mJ/cm2 using a metal halide lamp exposure device manufactured by Oak Seisakusho, and 2 kg/cm2 using a 1% aqueous sodium carbonate solution as a developer. Developed with spray pressure for 1 minute, rinsed with water spray, and dried. next,
It was thermally cured for 30 minutes in a hot air circulating oven at 150°C (hereinafter referred to as a cured coating).

[0095] The cured coating film on the copper foil was cross-cut into a 1 mm x 1 mm grid (100 pieces), cellophane tape was pasted thereon, and the tape was peeled off, and the state of peeling was visually evaluated.

◎; 100/100 with no peeling at all ○; 100/100 with a little peeling of the cross cut portion △; 99/100 to 50/100 ×; 49/100 to 0/100

5) Pencil hardness test Regarding cured coating film on copper foil, JIS K 5400
Hardness was measured according to the test method.

6) Apply flux (Asahi Spidiflux AGF-J3, manufactured by Asahi Chemical Research Institute) to the heat-resistant cured coating film, and
Place it on a solder bath at 0°C for 15 seconds, solder it, and then observe whether there are any abnormalities in the coating film. The paint film peels off or
If there is no abnormality such as blistering or solder getting under the coating, apply flux again and solder at 260°C for 15 seconds, then observe the coating. The maximum time without any abnormality on the coating film is defined as the heat resistance time.

7) Resistance to water-soluble flux for leveler Add water-soluble flux for leveler (manufactured by MEC Co., Ltd.) to the cured coating film.
W-139) was applied, immersed in a 260°C solder bath for 15 seconds, then immediately poured into 70-80°C warm water, left for 1 hour, washed with water, dried, and the coating film was Observe for abnormalities such as blistering, peeling, and whitening. In the present invention, the level of whitening was evaluated as follows.

0100: ○: No whitening △; Slightly whitening ×; Whitening

[0101] In the Examples and Comparative Examples, no blistering or peeling of the coating film occurred. Further, after pasting cellophane tape, it was peeled off to perform a peeling test to see if the coating film would peel off, and the following judgments were made.

0102] ◎; Items that do not peel off at all ○: Slightly peeled off. △; Significant peeling ×: The paint film peels off entirely.

8
) Resistance to methylene chloride The cured coating film is immersed in methylene chloride at room temperature, taken out every 15 minutes, and observed to see if there are any blisters on the coating film or if the glass substrate grains are visible, and to check for defects in the coating film. The time taken for this to occur was measured.

9) The acid-resistant cured coating film was immersed in a 10 vol% HCl aqueous solution, a 20 vol% sulfuric acid aqueous solution, and a 5 wt% caustic soda aqueous solution at room temperature for 3 hours each, and the whitening of the surface and the adhesion of the coating film (peeling test) were evaluated. did.

10) Plating resistance After pretreatment with Okuno Pharmaceutical's pretreatment solution for electroless nickel plating, a test board that had been subjected to electroless nickel plating and then electroless gold plating was subjected to a peeling test to check the peeling state. Observed.

The degree of plating resistance was determined as follows by applying a cellophane tape and then peeling it off to see if the coating film peeled off.

0107] ◎; Items that do not peel off at all ○: Slightly peeled off. △: Significant peeling ×: The paint film peels off entirely.

1
1) PCT (Pressure Cook Test)
After being left in steam at 121° C. and 2 atm for 5 hours, the coating film was judged to have passed if there were no abnormalities such as blistering, peeling, or discoloration.

12) Electrical insulation and galvanic corrosion resistance Electrical insulation was conducted in accordance with JIS C-6481. In addition, the galvanic corrosion resistance was determined using IPC SM using a comb-like pattern.
-840. In addition, the IOC stipulates the following three different test conditions.
We evaluated whether it passed or not.

Class I Temperature 35±5°C
, Temperature 90%, 4 days Class II Temperature 50±5℃, Humidity 90
%, 7 days Class III Temperature 25±2℃～65℃±
2℃ cycle, 90% humidity, 4 days

Examples 4 to 6 and Comparative Examples 3 to 5 Base resin 5 shown below was prepared.

Main ingredient 5: Acrylate of Synthesis Example 1 (70% solid content
Part 66 DPHA

Part 7 DETX

0.8 part Irgacure
907
Part 3.8 VT

2.8 parts talc

1.4 parts barium sulfate

12.6 parts Phthalocyanine green
0.5
Part Erosil R-812
2.8 parts
Antifoaming agent TSA-750S
Part 1

[0113] Main agent 5
Fine powder of epoxy resin YX-4000 was added as an additive to obtain photosensitive thermosetting resin compositions of Examples 4 to 6 and Comparative Examples 3 to 5. These compositions were made into cured products in the same manner as in Example 1, and their properties were evaluated. The results are shown in Table 3. Moreover, in the compositions of Examples 4 to 6,
All had a good shelf life of one month or more, and the developability was also good.

[0114]

[Table 3]

Examples 7 to 12 and Comparative Examples 6 to 7 Main ingredient 6 shown below was prepared.

Main ingredient 6: Acrylate synthesized in Synthesis Example 1 (70% solids) 47 parts DPHA


Part 4 DETX

0.5 part Irgacure
907
Part 3 V
T

Part 3 Talc

Part 19
barium sulfate

Part 19 Phthalocyanine green

0.5 part Erosil R-812

Part 2 Antifoaming agent TSA
-750S
Part 1

0117
] Various epoxy resins were added as additives to the main resin 6 to obtain photosensitive thermosetting resin compositions of Examples 7 to 12 and Comparative Examples 6 to 7. These compositions were made into cured products in the same manner as in Example 1, and their properties were evaluated.

A photosensitive thermosetting resin composition was prepared by adding 20 g of the following curing agent in terms of solid content to 100 g of base material 6. The types of curing agents are as follows.

Example 7: YX-4000 (manufactured by Yuka Shell Epoxy Co., Ltd., biphenyl-type epoxy resin) / Epoclone HP4032 (manufactured by Dainippon Ink & Chemicals Co., Ltd., special glycidyl ether-based epoxy resin with a naphthalene ring) = 5
0/50

Example 8; YX-4000/Epochron E
XA4506 (manufactured by Dainippon Ink and Chemicals, phenol novolac epoxy resin) = 90/10

Example 9; YX-4000/Epicron EXA4621 (
Manufactured by Dainippon Ink Chemical Industries, Ltd., cresol novolac epoxy resin) = 90/10

Example 10; EP
PN-502 (manufactured by Nippon Kayaku Co., Ltd., special glycidyl ether epoxy resin

Example 11; Epicron N
-510 (manufactured by Dainippon Ink & Chemicals, bisphenol A novolac type epoxy resin)

Example 12: Triglycidyl isocyanurate (manufactured by Yuka Shell Epoxy Co., Ltd., PF-810)

01
25] Comparative Example 6; Epicote 828 (manufactured by Yuka Shell Epoxy Co., Ltd., bisphenol A digcidyl ether)

01
26] Comparative Example 7; Epicote 1004 (manufactured by Yuka Shell Epoxy Co., Ltd., bisphenol A digidicidyl ether)

The main properties were evaluated and the results are shown in Table 4. In addition, the compositions of Examples 7 to 12 all had good shelf lives of one month or more, and also had good developability.

[0128]

[Table 4]

Claims (2)

[Claims] Claim 1: (a) Number average molecular weight is 500 to 500
0 conjugated diene polymer and/or copolymer with α,
A polymer and/or copolymer of a conjugated diene containing an acid anhydride group obtained by adding β-unsaturated dicarboxylic acid anhydride has the general formula [Formula 1] [wherein R1 and R2 are hydrogen atoms or Carbon number 1
~6 organic residues, R3 represents an alkylene group having 2 to 12 carbon atoms] having an alcoholic hydroxyl group represented by
, a photosensitive oligomer obtained by reacting β-unsaturated monocarboxylic acid ester and ring-opening at least 80 mol% of the acid anhydride groups of the adduct, (b) a photopolymerization initiator, (c
) an epoxy resin having two or more epoxy groups in the molecule, and (d) 2,4-diamino-6-vinyl-S-triazine and/or 2,4-diamino-6-methacryloyloxyethyl-S-triazine A photosensitive thermosetting resin composition having as an essential component. 2. The epoxy resin of the component (c) has the formula (
The photosensitive thermosetting resin composition according to claim 1, characterized in that it is an epoxy resin selected from I), (II) and (III). [Claim 2] [Chemical 3] [Chemical 4] [In each formula, G represents a glycidyl group] [Claim 3] The photosensitive thermosetting resin composition according to Claim 1 is applied to a printed wiring board. 1. A method for forming a solder resist pattern, which comprises coating the solder resist pattern, exposing it to light through a photomask, developing the unexposed portion to form a pattern, and then thermally curing it.