JPH02247654A - Alkali-developable photosensitive resin composition - Google Patents

Abstract

PURPOSE:To improve the resistance of a compsn. to electroless plating and to prevent defective adhesion and whitening phenomenon by incorporating a specified biphenyl type epoxy compd. into the compsn. CONSTITUTION:This compsn. is composed of 100pts.wt. alkali-developable polymer or oligomer (A) having carboxyl and vinyl groups in the same molecule, 10-200pts.wt. biphenyl type epoxy compd. represented by the formula (where each of R1-R8 is H or 1-3C alkyl), 5-50pts.wt. photopolymerizable monomer or oligomer and 1-30pts.wt. photopolymn. initiator or sensitizer. 3,3',5,5'- Tetramethylbiphenyl-4,4'-diglycidyl ether may be used as the component B and a polymer or oligomer of epoxy acrylate contg. a carboxyl group as the component A.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a photosensitive resin composition that can be developed with an alkaline aqueous solution, and more particularly relates to an electroless photosensitive resin composition that can be used as a permanent protective mask for printed wiring boards. The present invention relates to a photosensitive resin composition suitable for solder resist ink having plating resistance.

(Conventional technology) In recent years, high-density packaging of ICs and LSIs has progressed.

The printed wiring boards on which these devices are mounted are also becoming more and more densely packed, leading to miniaturization of lead wires, or a shift to surface mounting methods in which parts without lead wires are directly mounted on the surface of the board. The reality is that thermosetting solder resist inks produced by printing methods cannot meet these demands. As an alternative to this, the development of liquid photo solder resist using the principles of photography is being considered in many fields, and recently it has been used as an alternative to the conventional solvent-developed type due to its advantages in terms of working environment and processing cost. Photo solder resists that can be developed with weak alkaline aqueous solutions such as sodium carbonate aqueous solutions have been proposed. For example, Japanese Patent Application Laid-open No. 61-243,869,
JP-A No. 63-278.052.

discloses a liquid resist ink composition which has a novolak type or bisphenol A type epoxy resin skeleton and can be developed with a weak alkaline aqueous solution, which has excellent heat resistance and chemical resistance.

Also, JP-A-62-158.710, JP-A-622
No. 85.903 and JP-A-63-11,930 disclose an alkali-developable type resin in which a hese polymer is obtained by ring-opening addition of hydroxyalkylene (meth)acrylate to a copolymer of maleic anhydride and styrene. Compositions are disclosed. However, this type usually contains carboxyl groups. Therefore 1
For example, if it is used as a permanent resist for electroless gold plating, which is a step in the production of printed wiring boards that has been increasing in demand in recent years, it may cause poor adhesion on copper circuits and whitening on the glass fiber or epoxy resin base of the board after treatment. Since it causes development, it is difficult to use it practically.

Therefore, one object of the present invention is to provide an alkali-developable photosensitive resin composition having excellent electroless plating resistance.

(Means for Solving the Problems) In order to solve these problems, the inventors of the present invention have conducted extensive studies and have incorporated a biphenyl-type suboxy resin into a part of the photosensitive resin composition.

The inventors have discovered that the above problems can be solved and have arrived at the present invention.

That is, 9 the present invention provides (a) an alkali-developable polymer or oligomer having a carboxyl group and a vinyl group in the same molecule, (b) a biphenyl-type epoxy compound represented by the following general formula (1), and (C) photopolymerizable Sex or oligomer and! d) Alkali-developable polymer or oligomer fat consisting of a photopolymerization initiator or thickening agent
biphenyl type epoxy compound (b) per 100 parts by weight
), the ratio of the photopolymerizable monomer or oligomer (C) and the copolymerization initiator or sensitizer (d) is 10 to 200, respectively.
The gist of the present invention is an alkali-developable photosensitive resin composition characterized in that the content of the composition is 5 to 50 parts by weight, and 1 to 30 parts by weight.

(In the formula, R1 to R6 represent a hydrogen atom or an arnyl group having .about.3 carbon atoms.) The present invention will be described in detail below.

First, the alkali-developable polymer or oligomer (8) (hereinafter referred to as component (a)) having a carboxyl group and a vinyl group in the same molecule constituting the photosensitive resin composition of the present invention is 1, for example, 1. Carbogycyl group-containing evoxyacrylate-1, which is obtained by adding an acid anhydride to the hydroxyl group of acrylate; (2) ring-opening addition of 2-hydroxyalkylene (meth)acrylate to a copolymer of maleic anhydride and an unsaturated hydrocarbon; (2) Examples include (meth)acrylate copolymers containing carboxyl groups, in which a portion of the copolymer is substituted with a monomer containing vinyl groups.

Specific examples of (1) include phenol novolac type epoxy resin, cresol novolac type epoxy resin, and bisphenol A type epoxy resin.

Bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin.

Examples include those obtained by reacting an epoxy acrylate obtained by adding (meth)acrylic acid to an epoxy resin such as an alicyclic epoxy resin and an acid anhydride.

Further, as a specific example of (1), for example, hydroxyalkylene (meth)acrylate represented by the following formula (II) is added to a copolymer of maleic anhydride and an aromatic hydrocarbon having a vinyl group represented by styrene. Examples include things that have been added.

C11□=C(+?)-C-○-(C)1□)5-01
1 (IT) (In the formula, R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 3.) Furthermore, specific examples of Examples include those obtained by reacting a part of the carboxyl groups of a polymer obtained by addition polymerization including copolymerization of (meth)acrylic monomers containing (meth)acrylic monomers with glycidyl methacrylate.

Next, the biphenyl-type epoxy compound (b) (hereinafter referred to as component (b)) constituting the photosensitive resin composition of the present invention is represented by the general formula (I), and here R8 -R11 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and these may be the same or different. Particularly preferred among these are a hydrogen atom or a methyl group. A specific example is biphenyl-4
, 4'-diglycidyl ether, 3,3'-dimethylbiphenyl 4,4' diglycidyl ether, 3,5'-dimethylbiphenyl-4,4'-diglycidyl-thyl,
3.3',5.5'tetramethylbiphenyl-4,4
'-diglycidyl-thyl and the like. Particularly preferred among these is 313'+515'-tetramethylbiphenyl-4,4'-diglycidyl ether, which is commercially available as YX-4000 from Yuka Shell Casting Co., Ltd.

In addition, examples of the photopolymerizable monomer or oligomer (C) (hereinafter referred to as component (C)) constituting the photosensitive resin composition of the present invention include 2-hydroxyethic (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentayurythritol Examples include hexa(meth)acrylate, N,N'-methylenebis(meth)acrylate, diethylaminoethyl(meth)acrylate, tris(hydroxyethyl acryloyl)isocyanurate, and the like.

Further, 5 photopolymerization initiators or sensitizers (d) (hereinafter referred to as component (d)) constituting the resin composition of the present invention include 1, for example, acetophenone, 2,2-jethoxyacetophenone, p-dimethylacetophenone. , p-dimethylaminopropiophenone, dichloroacetophenone,
Acetophenones such as trichloroacetophenone and p-tert-butyltrichloroacetophenone, benzophenone, 2-chlorobenzophenone, p, p
-dichlorobenzophenone, p, p'-bisdimethylaminobenzophenone (also known as Michler's ketone) p,
p'-bisdiethylaminobenzophenone, 3.3',
Benzophenones such as 4°4'-tetra(tert-butylperoxycarbonyl)hensiphenone, benzyl.

Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ethers such as benzoin-n-butyl ether, hensyl dimethyl ketal, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, thioxanthone, 2
- Sulfur compounds such as chlorothioxanthone, 2.4-diethylthioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1. 2-Benzanthraquinone,
Anthraquinones such as 2,3-diphenylanthraquinone; organic peroxides such as azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, and cumene peroxide; mer, riboflavin tetrabutyrate.

Thiol compounds such as 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2,4.6-1 lis(trichloromethyl)-S-triazine, 2,2゜2-tribromoethanol, tri- Examples include organic halogen compounds such as bromomethylphenylsulfone.

These compounds can also be used in combination. It is also possible to add a compound that does not act as a photopolymerization initiator by itself, but can increase the ability of the photopolymerization initiator when used in combination with the above compounds. Examples of such compounds include tertiary amines such as triethanolamine, which are effective when used in combination with benzophenone.

The resin composition of the present invention comprises (a) component, (b) component, (C
) and (d), and the blending ratio of each component in this resin composition is 100% of (a) component.
Component (b) is 10 to 200 parts by weight, (
Component C) is 5 to 50 parts by weight, and component (d) is 1 to 30 parts by weight.

(If the blending ratio of component (b) to 100 parts by weight of the Al component is less than 5 parts by weight, heat resistance may be lacking, and when used as a solder resist, peeling may occur on the copper circuit during the soldering process.) First, it is undesirable because it lacks electroless gold plating resistance and coating hardness.

On the other hand, if it exceeds 200 parts by weight, the alkali developability after exposure deteriorates, which is not preferable.

Furthermore, if the blending ratio of component (C1) to 100 parts by weight of component (a) is less than 5 parts by weight, the photocuring speed will decrease and the crosslinking density will also decrease, resulting in insufficient film formability and film properties. On the other hand, if it exceeds 50 parts by weight, the crosslinking density is too high, which causes peeling of the film due to heat shrinkage during the soldering process, and at the same time, it is not preferable because the surface drying property decreases.

Furthermore, if the ratio of (dl component) to 100 parts by weight of component (a) is less than 1 part by weight, sufficient crosslinking cannot be achieved by light irradiation, while if it exceeds 30 parts by weight, This is undesirable because the resin reaches the substrate and the adhesion between the substrate and the resin deteriorates.

The photosensitive composition of the present invention can be suitably used as a solder resist for printed wiring boards.

It should be able to withstand electroless gold plating treatment.

After forming the solder resist film, electroless gold plating can be performed.

Examples of developing solutions suitable for alkaline development of the resin composition of the present invention include aqueous solutions of carbonates of alkali metals and alkaline earth metals, aqueous solutions of hydroxides of alkali metals, etc. Fine images can be precisely developed using a weakly alkaline aqueous solution containing 1 to 3% by weight of carbonates such as sodium carbonate, potassium carbonate, and lithium carbonate.

The alkaline development of the resin composition of the present invention is carried out at 10 to 50°C.
, preferably at a temperature of 20 to 40° C. using a commercially available developing machine or ultrasonic cleaner.

The resin composition of the present invention is cured not only by light but also by heat, but suitable light for curing by light includes light emitted from lamps such as ultra-high-pressure mercury lamps, high-pressure mercury lamps, and metal halide lamps. Examples include light.

The resin composition of the present invention can be suitably used as a solder resist for printed wiring boards as described above, but when used as a solder resist, first the resin composition of the present invention is applied to the surface of the printed wiring board. A film is formed by coating the resin composition as a solution or by pasting a dry film made of the resin composition of the present invention on the surface of a printed wiring board. A negative film is applied to the film, the exposed areas are cured by irradiation with actinic rays, and the unexposed areas are eluted using a weak alkaline aqueous solution.

After alkaline development, it is desirable to perform a curing treatment by heating in order to improve corrosion resistance. In the resin composition of the present invention, heat treatment not only significantly improves the durability against strong alkaline water but also achieves the requirements for solder resists such as adhesion to metals such as copper, heat resistance durability, and surface hardness. It also improves various properties. The heating temperature and heating time under these heat curing conditions are, for example, 80 to 200° C. and 10 minutes to 2 hours, respectively.

Examples of solvents suitable for preparing the solution of the resin composition in the present invention include ketones such as methyl ethyl ketone and methyl isobutyl ketone, and cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve cellosolve acetate.

As a method for applying the solution of the resin composition in the present invention to a printed wiring board, any method such as a solution dipping method, a spray method, or a method using a roller coater machine or a spinner coater can be adopted. . After applying the resin composition solution to a thickness of, for example, 20 to 30 μm by these methods.

A film is formed when the solvent is removed.

A dry film made of the resin composition of the present invention.

It is created by applying a solution of the above resin composition to a flexible support film such as a polyethylene terephthalate film and drying it. In addition, the dry film includes
It may be covered with a polyethylene film for protection.

The resin composition of the present invention contains, in addition to components (a) to (d).

Epoxy group curing accelerator, thermal polymerization inhibitor, filler paint,
Pigments, plasticizers, leveling agents, adhesion improvers, antifoaming agents,
Additives such as flame retardants, compounding agents such as organic solvents, and additives can be blended.

What are the types and amounts of such compounding agents and additives?

It is appropriately selected within a range that does not impair the properties of the resin composition of the present invention.

Epoxy group curing accelerators include amine compounds, imidazole compounds, carboxylic acids, phenols, quaternary
By using a small amount of these together and post-heating the coating film, the heat resistance, solvent resistance,
It can improve properties such as acid resistance, plating resistance, adhesion, electrical properties, and hardness, and is particularly suitable as a solder resist.

Examples of the thermal polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, pyrogallol, tert-butylcatechol, and phenothiazine.

Fillers include white alumina, clay, talc, finely powdered silica, barium sulfate, and barium carbonate.

Examples include magnesium oxide and titanium oxide.

Phthalocyanine green is used as a dye and pigment.

Examples include phthalocyanine blue, phthalocyanine yellow benzidine yellow, permanent red R, and brilliant carmine 6B.

Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, tricresyl, and the like.

Examples of antifoaming agents and leveling agents include silicone-based,
Examples include fluorine-based and acrylic-based compounds.

Examples of flame retardants include aluminum hydroxide.

Examples include inorganic flame retardants such as zinc borate, and organic flame retardants such as halogen-containing phosphates such as tris-(β-chloroethyl)-phosphate and pentachlorophenol methacrylate.

(Examples) The present invention will be specifically described below using nine examples. In addition, in the following, "parts" indicate "parts by weight."

Performance evaluation was performed as follows.

Among these, the drying properties of the coating film, the developability to alkaline aqueous solutions, and the n-light sensitivity are 20 to 3
A resist ink was applied to a thickness of 0 μm, and the resulting coating film was evaluated by drying it at 70° C. for 30 minutes using a hot air dryer.

In addition, it has excellent electroless gold plating resistance and adhesion to the substrate.

For solder heat resistance, hardness, chemical resistance, solvent resistance and insulation resistance, 500 mJ/crA after exposure and development.

Heating was performed at 145° C. for 50 minutes, and the coating film as a solder resist after completely curing was evaluated.

(1) Drying properties of coating films The drying properties of coating films were evaluated according to JIS K-5400.

The evaluation ranks are as follows.

○: No tack observed at all Δ: Slight tack observed ×: Significant tack observed (2) Developability with weak alkaline aqueous solution A 1% by weight aqueous sodium carbonate solution was used.

60 at 25°C under a pressure of 2.1 kg/cJ using a developing machine.
Developing was performed for seconds. After development, the remaining resin was visually evaluated under 30x magnification.

The evaluation ranks are as follows.

○: Good developability (no resist remains on the copper surface) ×: Poor developability (some resist remains on the copper surface) (3) Exposure sensitivity Kodak Step Tablet N112 (Yeast A negative film (manufactured by Mankodak Co., Ltd. with an optical density step of 0.15.21 steps) was adhered to the coating film, and an IK ultra-high pressure mercury lamp was used to produce a film of 500 mj/cn! The amount of light was irradiated.

Next, this coating film was subjected to the above-mentioned developability test using a weak alkaline aqueous solution, and the number of step tablets remaining on the copper foil was determined. In this evaluation method, the higher the sensitivity, the greater the number of remaining stages.

(4) Paint film hardness After exposure and development, the hardness of the paint film heated at 145°C for 50 minutes was determined by applying a load of 1 kg using a pencil hardness tester according to the JIS -5400 test method. Displayed as the highest hardness that will not cause scratches on the film.

The pencil used was ``Mitsubishi Hi-Uni'' (manufactured by Mitsubishi Pencil Co., Ltd.).

(5) Adhesion to the substrate After exposure and development, the coating film was heated at 145°C for 50 minutes.Cross cuts were made to create at least 100 goblets.Next, a peeling test was performed using adhesive tape. The state of peeling of the goblin was visually evaluated. The evaluation ranks are as follows.

○: No peeling was observed at all measurement points △: Peeling was observed at 1 to 20 of 100 measurement points x: ff1ll separation was observed at 21 or more of too measurement points (6) Solder heat resistance After exposure and development, the coating film heated at 145°C for 50 minutes was immersed in a 260'C solder bath for 20 seconds in accordance with JIS D-0202. The condition of the membrane was evaluated.

The evaluation ranks are as follows.

○: No abnormality in the appearance of the paint film ×: Blistering, melting, and peeling in the appearance of the paint film
Gold plating was performed for 15 minutes at a current density of IA/dm using IJ (gold plating liquid manufactured by Cellex Corporation in the United States) to deposit 2 μm thick gold on each test piece. Cross-cuts were made to form at least 100 cross-cuts, and then a peeling test was conducted using an adhesive tape, and the state of peeling of the cross-cuts was visually evaluated. The evaluation ranks are as follows.

○: No peeling was observed at all measurement points △: Peeling was observed at 1 to 20 of 100 measurement points x: Peeling was observed at 21 or more of the loO measurement points (8) Chemical resistance After exposure and development, the coating film was heated at 145°C for 50 minutes and immersed in each of the following chemicals at 25°C for 1 hour.

The appearance and adhesion after dipping were evaluated.

■Acid resistance 10wt HCI aqueous solution ■Alkali resistance 10% by weight N a OH aqueous solution ■Solvent resistance trichloroethane methylene chloride Isopropyl alcohol The evaluation ranks are as follows.

○: No abnormality ×: Dissolution or swelling (9) Insulation resistance A circular electrode was prepared according to JIS Z-3197, and the insulation properties under normal conditions and after 100 hours at 55° C. and 95% RH were measured using 5upper Megohmeter Mo manufactured by Toa Denpa ■.
Measured using del SM-5h.

Examples 1-6. Comparative Examples 1 to 4 +a) component, (b) component, (C) component, (d) component, filler.

A dye/pigment, a thermosetting agent, a thermal polymerization inhibitor, and an organic solvent were blended as described below, and kneaded using a three-roll test roll mill to prepare a resist ink.

Next, these resist inks were applied to a thickness of 15 to 25 μm on a degreased and cleaned copper-clad laminate with a thickness of 1.6 mm, dried, and then a negative film was adhered to the plate, and an IKW ultra-high pressure mercury lamp was used. (Y CP-46, manufactured by Furuya Shokai ■) was used to irradiate ultraviolet light with a wavelength of around 365 nm and an illuminance of 5 mW/ct for 100 seconds. After exposure, the developing machine (Y CE-8
5. (manufactured by Furuya Shokai ■) was developed with a 1% by weight aqueous sodium carbonate solution at 25° C. for 60 seconds to remove the unexposed portions of the coating film. After that, use a hot air dryer to dry at 145℃ for 50 minutes.
A heat treatment was performed for a minute.

The obtained samples were tested for electroless gold plating resistance of the coating film, as well as drying properties of the coating film, developability to alkaline aqueous solutions, exposure sensitivity, coating hardness, adhesion to the substrate,
Solder heat resistance, hardness, chemical resistance, electroless gold plating resistance, and insulation resistance were evaluated.

Tables 1 and 2 show the results obtained for some of the blending ratios.

Blending ratio> ■Examples 1 to 3. Blend ratio of Comparative Examples 1 and 2 (a) Bisphenol A type eboxia (see Table 1) in carboxyl group-containing epoxy acrylate obtained by adding succinic anhydride to the hydroxyl group of acrylate) 3.3', 5. 5'-tetramethyl (see Table 1) biphenyl-4,4'-diglycidyl ether (C1 dipentaerythritol hexaa 5 parts acrylate + dl benzophenone 4.5 parts diethylaminobenzophenone 0.5 parts other ingredients barium sulfate 15 Part Phthalocyanine Green 0.5 part Dicyandiamide
1.0 part Hyde ■Quinone monomethyl ether 0.05 part Cellosolve acetate) 23.5 parts ■Example 4
~6. Blending ratio of Comparative Examples 3 to 4 +8) Cross copolymer of styrene and maleic anhydride (see Table 2)
Carboxyl group-containing polymer (b) obtained by adding hydroxyethyl acrylate to SMA Resun 1000 (manufactured by Chemi IL Co., Ltd.) 3.3', 5. 5'-tetramethyl (
(See Table 2) Biphenyl-4,4'-diglycidyl ether (C) Pentaerythritol triacrylate (d
l Benzophenone diethylthioxanthone and other compounding agents Finely powdered silica phthalocyanine green dicyandiamide Hydroquinone Carpitol acetate 5 parts 4.5 parts 0.5 parts 0.5 1.5 0.1 19.9 From Tables 1 and 2 As is clear, the resin composition of the present invention has excellent electroless plating resistance.

It can be seen that other properties are also excellent.

(Effects of the Invention) The resin composition of the present invention has excellent electroless plating resistance such as electroless gold plating resistance that could not be achieved with conventional resin compositions. Therefore, according to the resin composition of the present invention, electroless gold plating can be performed after forming a solder mask, and waste in electroless gold plating can be eliminated.

Furthermore, the resin composition of the present invention has acid resistance, alkali resistance,
It has excellent solvent resistance, soldering heat resistance, electrical insulation mechanical strength, surface hardness, etc., so it is not only suitable for use as a permanent protective mask such as Menki resist in the full additive solder resist method, but also for printed wiring. Etching resists related to boards, glabellar insulating materials, photosensitive adhesives, paints, plastic reliefs, plastic hard coating agents, and PS plates as offset printing plates.

It can be used in a wide range of fields such as photosensitive liquids for screen printing and resist inks.

Claims (1)

[Claims] (1) (a) An alkali-developable polymer or oligomer having a carboxyl group and a vinyl group in the same molecule, (b) a biphenyl-type epoxy compound represented by the following general formula (I), (c) a photopolymerizable monomer, or Biphenyl-type epoxy compound (b), photopolymerizable monomer or oligomer (c) and copolymerization based on 100 parts by weight of an alkali-developable polymer or oligomer (a) consisting of an oligomer and (d) a photopolymerization initiator or sensitizer. The proportion of initiator or sensitizer (d) is 10 to 10, respectively.
200 parts by weight, 5 to 50 parts by weight, and 1 to 30 parts by weight, an alkali-developable photosensitive resin composition. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 to R_8 represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)