JPS61273537A - Image forming material and formation of circuit by using it - Google Patents

Abstract

PURPOSE:To lower cost in steps for forming and removing a resist pattern and to improve public sanitation by incorporating a specified film forming polymer in a photopolymerizable composition layer as a stripping development type dry film resist. CONSTITUTION:The photopolymerizable composition layer of an image forming material is composed essentially of a) the film forming polymer composed essentially of a polymer soluble or swellable in an aqueous solution of alkali and a chlorinated polymer, b) a photopolymerizable unsaturated compound, c) and a photopolymerization initiator, and the image forming material is the stripping development type dry film resist composed of a transparent support and this photopolymerizable composition layer. Since the component a) contains an alkali-soluble for swellable polymer, this photopolymerizable composition layer is given with solubility or swellability in an aqueous solution of alkali after photohardening, thus permitting the obtained resist to be made advantageous from the view points of the manufacture cost and public sanitation by using no organic material in the step for removing the resist.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming material used for manufacturing printed wiring boards and the like, and a circuit forming method using this material.

[Conventional technology]

Conventionally, a photopolymerizable composition layer is provided on a transparent support, and the photopolymerizable composition layer is laminated on the substrate on which a circuit is to be formed so that it becomes the contact surface, and then exposed to light in a pattern. By peeling off the transparent support, the non-exposed portion of the photopolymerizable composition layer is peeled off together with the support, and the exposed portion remains on the substrate to form a predetermined resist pattern, so-called peeling. Various image forming materials made of developable dry film resists have been proposed.

Formation of a circuit using such an image forming material involves forming a resist pattern on a substrate using the above method, and then applying a resist pattern to the non-exposed portion of the partial photopolymerizable composition layer on the substrate that does not have a resist. For example, if this board is a printed wiring board consisting of an insulating base and a conductive layer, the part from which the conductive layer has been peeled off and removed may be subjected to necessary steps such as etching the conductive layer or plating the conductive layer. By performing a circuit formation process and then removing the patterned resist,
It will be done.

In this circuit formation method, the resist pattern can be formed on the substrate by peeling off the transparent support, which means that there is no need to use liquid for development, which has the advantage of being good for public health. Furthermore, since no developer is used, the development cost is low and the development operation is simple.

[Problem that the invention seeks to solve]

However, after a resist pattern is formed by such peeling development and the necessary circuit forming processing such as etching and plating is performed, an organic solvent is generally used in the step of removing the patterned resist. A method is adopted in which the resist is dissolved and removed using a solvent. Therefore, even if stripping development can reduce costs and provide public health benefits, as long as organic solvents are used in the resist removal step, there will be no public health problems or increased costs at this step. still remains.

Therefore, an object of the present invention is to provide an image forming material and a circuit forming method using the same, which can reduce costs and improve public health both in the resist pattern formation stage and in the resist pattern removal stage.

[Means for solving problems]

As a result of intensive studies to achieve the above object, the inventors found that when a photopolymerizable composition layer containing a specific film-forming polymer is used as a #release-developable dry film resist, In addition to being able to form a desired resist pattern, an alkaline aqueous solution can be applied to remove it, and this aqueous solution can reduce costs and improve public health compared to the conventional organic solvents. This led to the completion of this invention.

That is, the present invention provides a transparent support, a) a film-forming polymer whose main components are a polymer soluble or swellable in an alkaline aqueous solution and a halogen-containing polymer, b) a photopolymerizable unsaturated compound, and C) a photopolymerizable A first invention relating to an image forming material comprising a peelable and developable dry film resist comprising a photopolymerizable composition layer containing an initiator as an essential component, and the above image forming material is applied onto a substrate on which a circuit is to be formed. Then, the photopolymerizable composition layer side was laminated so that the contact surface was exposed, patterned exposure was performed, a resist pattern was formed by peeling development, and required circuit formation processing such as etching and plating was performed. This invention also comprises a second invention relating to a circuit forming method characterized in that the patterned resist is then removed using an alkaline aqueous solution.

[Structure and operation of the invention]

The photopolymerizable composition layer in the image forming material of this invention is
a) a film-forming polymer whose main components are a polymer soluble or swellable in an alkaline aqueous solution and a halogen-containing polymer, b) a photopolymerizable unsaturated compound, and C) a photopolymerization initiator as essential components. Since the component a contains a polymer that is particularly soluble or swellable in an aqueous alkaline solution, the composition layer after exposure and curing is imparted with the property of being soluble or swellable in an aqueous alkaline solution.

The polymer soluble or swellable in the aqueous alkali solution used in this invention is a homopolymer of acrylic acid or methacrylic acid, or a combination of these unsaturated monomers with an acrylic acid alkyl ester, a methacrylic acid alkyl ester, acrylamide, or acrylonitrile. , copolymers with other monomers such as styrene, or copolymers of maleic anhydride, maleic acid, maleic acid half esters, etc. with other monomers such as styrene, acrylic acid alkyl esters, methacrylic acid alkyl esters, butadiene, etc. There are copolymers of

In this invention, the halogen-containing polymer used in combination with the polymer soluble or swellable in an aqueous alkaline solution is
It is used to impart peel developability to the photopolymerizable composition layer, and specific examples thereof include chlorinated polyethylene, chlorinated polypropylene, and chlorinated rubber.

The film-forming polymer as component a is mainly composed of the above-mentioned polymer that is soluble or swellable in aqueous alkaline solution and a halogen-containing polymer. If both polymers undergo phase separation, favorable results may not be obtained. Therefore, in order to prevent this, it is preferable to use a third polymer that is compatible with both of them, and polymethyl methacrylate can be suitably used as an example of this.

The proportion of each of these polymers used is 50 to 90% by weight of a polymer that is soluble or swellable in an alkaline aqueous solution;
Preferably, the halogen-containing polymer contains 50 to 80% by weight of 10
-50% by weight, preferably 1θ - 40% by weight, and 0-40% by weight of a third polymer having good compatibility with both, preferably 1
It is preferable to adjust the amount to 0 to 40% by weight. If the content of the polymer that is soluble or swellable in an alkaline aqueous solution is less than 50% by weight, the removability of the resist by the aqueous alkaline solution will be poor, and if the halogen-containing polymer is less than 10% by weight, problems will likely occur in peeling and developability, both of which are undesirable. .

The photopolymerizable unsaturated compound of component b includes a monoethylenically unsaturated compound having one ethylenically unsaturated bond in the molecule and a polyethylenically unsaturated compound having two or more ethylenically unsaturated bonds. Particularly preferably, a polyethylenically unsaturated compound is used alone or in a mixed system with a monoethylenically unsaturated compound.

Examples of monoethylenically unsaturated compounds include acrylic acid or its esters, methacrylic acid or its esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, N-vinyl compounds, styrenes, These include crotonic acid esters.

Specific examples of acrylic esters include propyl acrylate, butyl acrylate, amyl acrylate,
2-ethylhexyl acrylate, octyl acrylate, etc.; methacrylate esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, etc.; acrylamides include acrylamide, N-alkyl group is methyl group, ethyl group, etc. basis,
Butyl group, isopropyl group, tert-butyl group, 2-
N-alkyl acrylamide, which consists of an ethylhexyl group, etc., is methacrylamide, and N-alkyl methacrylate, whose N-alkyl group is a methyl group, ethyl group, isopropyl group, tert-butyl group, 2-ethylhexyl group, etc. There are amides, etc.

In addition, allyl compounds include allyl esters such as allyl acetate, allyl caproate, allyl caprylate, allyl laurate, and allyl palmitate, and the vinyl ethers include hexyl vinyl ether, octyl vinyl ether,
Alkyl vinyl ethers such as decyl vinyl ether and 2-ethylhexyl vinyl ether are 1, and vinyl esters such as vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, and vinyl caproate are N-
Vinyl compounds include N-vinylpyrrolidone, styrenes include styrene, methylstyrene, chloromethylstyrene, alkoxystyrene, halogenated styrene, and styrene benzoate, and crotonate esters include methyl crotonate, ethyl crotonate, and crotonate. Examples include butyl, hexyl crotonate, and isopropyl crotonate.

Next, examples of polyethylenically unsaturated compounds include polyacrylates and polymethacrylates of polyhydric alcohols. The polyhydric alcohol mentioned above is
Polyethylene glycol, polypropylene oxide, polybutylene oxide, (β-hydroxyethoxy)benzene, glycerin, diglycerin, neopentyl glycol, trimethylolpropane, triethylolpropane, pentaerythritol, dipentaerythritol,
Sorbitan, sorbitol, 1,4-butanediol,
1,2,4-butanetriol, 2-ptento-4-diol, 2-butyl-2-ethyl-propanediol,
Examples include 2-butenoto-4-diol, 1,3-propanediol, triethanolamine, decalindiol, and 3-chloroto-2-propanediol.

In addition, other examples of polyethylenically unsaturated compounds include:
There are acrylate oligomers and methacrylate oligomers having two or more acryloyl groups or methacryloyl groups in the molecule, which are commercially available under the names of oligoester 7 acrylate, oligoester methacrylate, epoxy acrylate, epoxy methacrylate, urethane acrylate, urethane methacrylate, etc.

The photopolymerizable unsaturated compound as component b consisting of such constituent components is usually in the range of 10 to 500 parts by weight, preferably 30 to 200 parts by weight, based on 100 parts by weight of the film-forming polymer as component a. used in If this amount is too small, the photopolymerizability, that is, the exposure curing property will be poor, and if it is too large, the peeling performance will be poor, and in either case, the peeling and developing properties are likely to be impaired. Furthermore, if the amount of component b is too large, the solubility or swelling property of the cured product in an alkaline aqueous solution decreases, which tends to cause problems in resist removability.

The photopolymerization initiator as component C used in this invention includes a wide variety of conventionally known photopolymerization initiators. Specific examples include carbonyl compounds, organic sulfur compounds, peroxides, redox compounds, azo and diazo compounds, and photoreducible dyes.

Examples of the above carbonyl compounds include benzoin, benzophenone, anthraquinone, 2-methylanthraquinone, 2-tert-butylanthraquinone, 9,10-phenanthrenequinone, diacetyl, benzyl, Michler's ketone, 4,4'-hisdiethyl, aminobenzophenone, etc. Examples of organic sulfur compounds include dibutyl disulfide, dioctyl disulfide, dibenzyl disulfide, diphenyl disulfide, dibenzoyl disulfide, and diacetyl disulfide.

In addition, as peroxides, hydrogen peroxide, g-tert-
Butyl peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, etc. are used as redox compounds. Diferric ions and peroxides are used as azo and diazo compounds such as α・α′-azobisisobutyronitrile, 2-azobis-2-methylbutyronitrile,
Examples of photoreducible dyes include rose bengal, erythrosin, eosin, acriflavin, riboflavin, and thionin.

These photopolymerization initiators may be used alone or in combination of two or more. The amount used is usually 0.1 parts by weight per 100 parts by weight of the photopolymerizable unsaturated compound as the above-mentioned component.
The amount may be in the range of 20 parts by weight.

The photopolymerizable composition layer of this invention comprises a, b as described above.
, component C are essential components, but in addition to these components, various additives such as a thermal polymerization inhibitor, a coloring agent, an adhesion improver, a filler, and a plasticizer may be included as necessary.

In this invention, such a photopolymerizable composition layer is obtained by uniformly dissolving and dispersing each of the above components in a solvent, and depositing this on a transparent support to a thickness of 5 to 1100 II, preferably 5 to 1,100 II after drying.
It is formed by coating and drying to a thickness of ~50 μm.

As the above-mentioned solvent, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and esters such as ethyl acetate, butyl acetate, and amyl acetate are preferably used. Also, aromatic hydrocarbons such as toluene, benzene, xylene, carbon tetrachloride, chloroform, trichloroethyl! Halogenated hydrocarbons such as carbon dioxide, methylene chloride, alcohols such as methanol, ethanol, propatool, and butanol can also be used in the form of mixed solvents.

Moreover, as the above-mentioned transparent support, one is selected that has good transmittance to light in a wavelength range of 300 to 500 nm that allows photopolymerization of the photopolymerizable composition layer, and has a uniform surface. Specific examples of such transparent supports include various plastic films such as polyethylene terephthalate, polypropylene, cellulose triacetate, cellulose diacetate, polycarbonate, and cellophane. Among these, polyethylene terephthalate is preferred from the viewpoint of strength, two-dimensional stability, heat resistance, and moisture absorption. The preferred thickness of the transparent support is 10 to 50 μm.

The image-forming material of the present invention consists of a peelable and developable dry film resist comprising the transparent support obtained as described above and a photopolymerizable composition layer, and as described above, component a is present in the composition layer. A major feature is that it contains the above-mentioned specific polymer. In addition, in order to protect the photopolymerizable composition layer during storage, a protective film made of polyethylene, polypropylene, or various plastic films subjected to release treatment may be provided on the composition layer. You can also do this.

Next, a method for forming a circuit using the image forming material of the present invention constructed as described above will be explained.

In this method, first, the surface of a substrate on which a circuit is to be formed, such as a copper-clad laminate board for obtaining a printed wiring board, is cleaned, and the image forming material of the present invention having the above structure is applied to the cleaned surface for protection. If a film is included, the protective film is peeled off and the photopolymerizable composition layer is pressed onto the substrate so that the contact surface becomes the contact surface. The pressure bonding temperature at this time is usually about 20 to 80°C.

Next, for example, a negative mask having a circuit pattern is placed on a transparent support and exposed to light from a light source containing light with a wavelength of 300 to 500 nm, such as a 'Gf high pressure mercury lamp, ultra-high pressure mercury lamp, xenon lamp, carbon arc lamp, etc. .

After being exposed in this way, the substrate is preferably
When the transparent support is peeled off from the substrate while kept at a temperature of ℃, the photopolymerizable composition layer in the exposed areas in pattern exposure is photocured and remains on the substrate, while the unexposed areas remain uncured and remain on the transparent support. The resist material is peeled off along with the resist material, thereby forming a desired resist pattern on the substrate.

Next, the exposed surface of the substrate without resist, or in the case of a printed wiring board, the copper surface without resist, is etched using an etching solution such as ferric chloride solution or cupric chloride solution. Thereafter, by immersing it in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide having a molecular weight of 3 to 8, preferably at a temperature of 40 to 80°C, or by spraying such an alkaline aqueous solution, The hardened resist dissolves or swells and peels off from the substrate.

Thereafter, by thoroughly rinsing with water and drying, a positive image circuit pattern etched onto the substrate is obtained.

In addition, when a positive mask is used instead of a negative mask in the above method, after forming a resist pattern in the same manner as above, copper, solder, gold, etc. are applied to the substrate surface that does not have a resist instead of etching. By performing plating treatment and then removing the resist using an alkaline aqueous solution in the same manner as described above, a positive image circuit pattern plated on the substrate can be obtained.

〔Effect of the invention〕

As described above, in this invention, by including a specific film-forming polymer in the photopolymerizable composition layer of the peel-and-developable dry film resist, a resist pattern can be easily formed by peel-and-develop. In addition, since it can be removed using an alkaline aqueous solution that is inexpensive and poses few public health problems, there is an effect that circuit formation can be performed more cheaply and hygienically than in the past.

〔Example〕

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example 1 Superchron CPE-907-HA) Benzophenone 6 parts paramethoxyphenol
0.1 part tribromomethylphenylsulfone 1 part crystal violet 0.2
1 part methyl ethyl ketone 300 parts A solution of the photopolymerizable composition was prepared by uniformly dissolving and mixing the above materials. This liquid was applied onto a polyethylene terephthalate film with a thickness of 25 μm so that the thickness after drying would be 25 μm, and then dried at 80°C for 5 minutes to form an image forming material consisting of a peelable and developable dry film resist. Obtained.

This image forming material was laminated under pressure at a temperature of 50°C on the copper-clad surface of a copper-clad glass epoxy laminate substrate whose surface had been cleaned, with the photopolymerizable composition layer side facing the contact surface, and then A negative original having a circuit pattern was brought into close contact with the transparent support of this image forming material, and a 60cm
Exposure was performed for 10 seconds from a distance of m. Next, when the substrate was heated to 30°C and the polyethylene terephthalate film, which is the transparent support of the image forming material, was peeled off from the substrate,
The non-exposed portions were peeled off from the substrate together with the film, and a resist pattern constituting a positive image circuit consisting of the cured exposed portions was formed on the copper-clad surface of the substrate.

The copper-clad substrate having the resist pattern thus obtained was etched with a ferric chloride aqueous solution at 40 degrees Baumé to remove the exposed copper foil. After that, a sodium hydroxide aqueous solution with a concentration of 3% by weight (liquid temperature 50%
℃) for 5 minutes, the cured resist swelled and peeled off from the substrate. A desired printed wiring board was obtained by washing this board with water and drying it.

Example 2 Example 1 except that a positive original was used, which was the opposite of the negative original.
In the same manner as above, a resist pattern constituting a negative circuit was formed on a copper-clad laminate board. Next, solder plating was applied to the exposed copper-clad surface of this board, and the resist was removed with an alkaline aqueous solution to form a solder-plated positive circuit pattern on the copper-clad surface.

After that, etching was performed at 40°C using an alkaline etchant (trade name manufactured by Japan Metal Finishing Co., Ltd.) that does not melt solder but can melt copper, and the desired solder-plated printed wiring board was obtained. .

Comparative Example 1 Example 1, except that 50 parts of chlorinated polyethylene (same as Example 1) and 50 parts of polymethyl methacrylate (same as Example 1) were used instead of the film-forming polymer of Example 1. An image forming material was obtained in the same manner as in Example 1. Furthermore, using this material, lamination on a substrate, exposure and peeling development were performed in the same manner as in Examples 1 and 2.
A resist pattern similar to 2 was able to be formed.

However, after applying the same etching or plating treatment as in Example 1.2, the resist film was immersed in an alkaline aqueous solution for 5 minutes under the same conditions, but the hardened resist film could not be peeled off from the substrate. Ta.

Comparative Example 2 The film-forming polymer of Example 1 was replaced with 40 parts of polymethyl methacrylate (same as in Example 1) and 60 parts of styrene-isopropyl maleate half ester (same as in Example 1). An image forming material was obtained in the same manner as in Example 1.

After laminating and exposing this material to a substrate in the same manner as in Examples 1 and 2, peeling and development was performed, but both exposed and non-exposed areas remained on the substrate, leaving only the polyethylene terephthalate film. has peeled off. That is, with the above materials, it was not possible to form a desired resist pattern on the substrate by peeling and development.

Comparative Example 3 The film-forming polymer of Example 1 was replaced with 20 parts of polymethyl methacrylate (same as Example 1) and 80 parts of styrene-isopropyl maleate half ester (same as Example 1). An image forming material was obtained in the same manner as in Example 1.

Using this material, the substrate was laminated and exposed in the same manner as in Examples 1 and 2, and then peeled and developed. Therefore, the desired resist pattern could not be formed.

Part name of Example 3 Super Chron CR-) J rate benzophenone 5 parts paramethoxyphenol o, i 5p-) Luenesulfonyl chloride 1 part Victoria Pure Blue 0.3 part Methyl ethyl ketone
An image forming material was prepared in the same manner as in Example 1 using 300 parts of the above photopolymerizable composition solution, and a circuit was formed using this material in the same manner as in Examples 1 and 2.
Both the formation of a resist pattern by peeling and development and the removal of the patterned resist by an alkaline aqueous solution were easy, and a printed wiring board having the same desired circuit pattern as in Example 1.2 could be obtained.

Example 4 (CPE-907LTA) Diethylthioxanthone 3 parts Isoamyl dimethylaminobenzoate 3 parts Paramethoxyphenol 0.1 part Tribromomethylphenyl sulfone 1 part Victoria Pure Blue 0
．． 3 parts Methyl ethyl ketone 300 parts An image forming material was prepared in the same manner as in Example 1 using the above photopolymerizable composition solution, and using this material, Example 1.
When a circuit was formed in the same manner as in Example 2, it was found that both the formation of a resist pattern by peeling development and the removal of the patterned resist with an alkaline aqueous solution were easy.
A printed wiring board having a desired circuit pattern similar to that of , 2 could be obtained.

Claims (2)

[Claims] (1) A transparent support, a) a film-forming polymer whose main components are a polymer soluble or swellable in an alkaline aqueous solution and a halogen-containing polymer, b) a photopolymerizable unsaturated compound, and c) a photopolymerization initiator. An image-forming material comprising a peel-and-developable dry film resist and a photopolymerizable composition layer contained as an essential component. (2) A transparent support, a) a film-forming polymer whose main components are a polymer soluble or swellable in an alkaline aqueous solution and a halogen-containing polymer, b) a photopolymerizable unsaturated compound, and c) a photopolymerization initiator. An image forming material consisting of a peelable and developable dry film resist containing a photopolymerizable composition layer as an essential component is placed on a substrate on which a circuit is to be formed, so that the photopolymerizable composition layer side is the contact surface. After laminating and exposing in a pattern, a resist pattern is formed by peeling and development, and after performing necessary circuit forming processing such as etching and plating, the patterned resist is removed with an alkaline aqueous solution. A method for forming a circuit.