JPS6244256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When producing dry photosensitive materials such as lithographic printing plates, photoresists, etc., negative or positive photosensitive compositions are used. Negative types are those that become image-wise insolubilized when exposed to actinic radiation. Since the exposed areas become relatively insoluble, the selected developer dissolves or removes the unexposed areas of the composition, leaving the exposed areas intact. The resulting image therefore corresponds to the inverse of the original in terms of contrast, ie to a negative image. Conversely, in positive tone, upon exposure to actinic radiation, the exposed areas become more soluble and developable, and these areas are removed with a selected developer, leaving the unexposed areas intact. Formation of the image in this case results in an image that corresponds to the original image in terms of contrast, ie a positive image.

In the special field of photoresist production, the use of photoresists on a support by image-wise protection of the support material from subsequent chemical or physical manufacturing steps, such as chemical etching, vacuum evaporation and electrodeposition, is important. Photoresists are commonly utilized to facilitate imaging. In other words, when the photoresist material is exposed and developed, the underlying support on which the photoresist is placed is exposed to subsequent physical processing depending on the image, which processing is protected by the corrosion-resistant material. It only works on the parts that aren't there. In manufacturing copper-clad circuit boards, a photoresist is typically applied to the surface of the circuit board, which is then imaged and developed. Following this initial treatment, the etching solution is sprayed onto the support under high pressure,
The metallic copper not protected by the photoresist is removed by an etching agent, and after removing the remainder of the photoresist, a metal circuit structure with an image is obtained.

In order to accurately reproduce the shape of the circuit, the photoresist has high adhesion and high internal strength to the substrate on which it is applied. Adhesion is necessary to prevent excessive undercutting of the resist by the etchant and thus reduction in resolution, and internal strength is necessary to maintain proper circuit geometry. Dry film resists have favorable flexibility, thermopressure lamination capability, reasonably rapid exposure capabilities, excellent development properties due to medium pressure spraying of developer solutions,
It should have excellent coating quality (ie, no physical defects), the ability to quickly chemically strip or remove the photoresist after use, and the ability to produce a visible image upon exposure to actinic radiation.

Dry negative film resists have, of course, been known for a long time. One of the important properties required for all resists is resolution. Positive-tone resists have inherently higher resolution than their negative-tone counterparts. This difference is due, in part, to the generally required presence of an oxygen-impermeable barrier film before and during exposure of the negative resist. The reason for the necessity of this barrier film is that conventional negative-tone materials are usually oxygen sensitive.

Typical resolution requirements in the electronics industry are as follows. In the manufacture of general purpose printed circuit boards, 10 mil wires are typically required in 10 spaces. Precision circuits typically require 1 mil wire in 1 mil spacing. The microelectronics industry requires lines and spacing better than 0.1 mil.

Currently, the dry film resist market actually consists of only negative resists. This is because a positive film photoresist that meets the above criteria has not been developed. Positive film resists are usually too brittle, resulting in flaking of the resist even when the support sheet is gently bent, coating defects, lack of internal cohesive strength that causes the resist to fracture during etching, and resistance to the support surface. Indicating lack of photoresist adhesion.

It has been found that new positive-working photosensitive compositions can be used to produce dry film photoresists that meet many of the criteria set forth above. Furthermore, the photosensitive composition is oleophilic, i.e. ink receptive, in the cured state and is therefore used as a coating on aluminum or stainless steel surfaces to obtain lithographic printing plates or in the production of bimetallic printing plates. Can be used.

According to the present invention, (a) a crosslinked urethane resin formed by a catalytic crosslinking reaction of a non-thermally reactive noporac phenolic resin and a polyisocyanate compound;
A positive-working photosensitive composition having excellent usability as a photoresist, comprising an epoxy resin having an epoxy equivalent weight of less than 400, a curing agent for the epoxy resin, and (c) a positive-working photosensitizer of quinone-based diazooxides. is provided.

When the composition is suitably applied to a support (which may be a temporary support layer and a peelable film or a support to which the composition is coated prior to processing) and dried, the epoxy resin cures and the resulting dry film is called a dry film. It has ideal utility as a photoresist. Furthermore,
The dry film is oleophilic and therefore can be used as a printing plate surface.

In dry coated form, the positive-working compositions of the present invention include two networks of intermixed and interwoven polymeric resins. The first of these networks consists of a crosslinked urethane resin formed from the crosslinking reaction of a diisocyanate and a novolac phenolic resin, and the second consists of a thermosetting epoxy resin. This resin mixture contains a positive photosensitizer mixed therein to impart photosensitivity to the system.

Urethane resins are formed by the catalytic crosslinking reaction of novolak phenolic resins with polyisocyanates, preferably triisocyanates or diisocyanates, most preferably long chain diisocyanate compounds, in solution.

The components used to form the urethane are simply dissolved in a suitable solvent with a suitable catalyst, and the crosslinking reaction begins. When the solution viscosity stabilizes,
The reaction is complete.

The novolac phenolic resin should normally comprise about 40%, especially 50-70% by weight of the composition, and should not be thermally reactive. In the present invention, non-thermally reactive means that the resin does not substantially polymerize merely by heating. Substantial polymerization occurs when the average molecular weight increases by at least 10%. Advantageously, the average molecular weight increases by no more than 4%, if at all, when heated. Increasing the novolak resin concentration increases the brittleness of the film and disadvantageously increases the solubility of the unexposed portions of the film, resulting in an insufficient solubility difference between the exposed and unexposed portions of the film. After imagewise exposure to actinic radiation, the concentration decreases.
The film will not develop properly. Preferred novolac resins are novolac phenol/formaldehyde resins with a molecular weight of about 500 to 1000. These resins are described in US Pat. No. 4,148,655, which uses a number of different phenolic components.

Polyisocyanates useful in the present invention include:
Includes the conventional aromatic and aliphatic polyisocyanates. Advantageously, the polyisocyanates have long chains. That is, the number of isocyanate groups is about 10 to 40.
Advantageously, they are bonded via a linking chain of 50 or 50 carbon atoms. Smaller (eg, 6 carbon atoms) and larger chain aromatic and aliphatic diisocyanates are, of course, also useful in the practice of this invention. For example, isophorone diisocyanate, toluene diisocyanate, and any other diisocyanate are particularly useful. Advantageously, the polyisocyanate is present in a concentration of about 6 to 12 parts by weight per 100 parts of novolak resin present, depending on its molecular weight or isocyanate equivalent weight. Generally, the weight percent should not exceed the range of about 3 to 20 percent by weight of the novolak resin. As this amount increases, the resulting film becomes significantly brittle, has insufficient internal strength and, in the case of photoresists, tends to have reduced adhesion to the substrate to which it is laminated. As the amount is reduced, the film tends to stack properly and the exposed areas cannot be washed away during development. Any catalyst known to catalyze the formation of urethanes can be used. The most preferred catalysts are tertiary amines such as 1,4-diazabicyclo(2,2,2)-octane and 2,
4,6-tris(dimethylaminomethyl)phenol.

The concentration of catalyst is not critical as long as a sufficient amount is present to effect the crosslinking reaction. usually,
Amounts of about 0.05 parts by weight or more per 100 parts of novolac resin are more than sufficient to ensure a complete crosslinking reaction, although as little as 0.01 parts may be sufficient.

Once the urethane formation is complete, a polymerizable epoxy resin having an epoxide equivalent weight of less than about 400 is added to the solution along with a curing agent. A preferred representative epoxy resin is the diglycidyl ether of bisphenol A. The concentration of epoxy resin should be from about 20 parts by weight to about 40 parts by weight per 100 parts of novolak resin. Increasing the density beyond this tends to increase the flexibility of the resulting dry photosensitive film, but reduces the possibility of imagewise exposure and development. As the concentration decreases, the adhesion and handling properties of the resulting dry film tend to decrease.

Epoxy hardeners are, for example, aliphatic or aromatic amines, aliphatic or aromatic anhydrides, disulfones, nitriles and other known epoxy hardeners. Any of these and other curing agents can be used in the practice of this invention. Preferred curing agents include phthalic anhydride, diaminodiphenylsulfone or mixtures thereof. Usually about 5 parts to about 50 parts of hardener per 100 parts of epoxy resin.
part is sufficient to ensure curing of the epoxy resin.

If no epoxy curing agent is added or the epoxy resin is not properly cured, the resulting film tends to be brittle and lacks the internal cohesive strength necessary for photoresist performance. Conversely, when the epoxy resin cures satisfactorily, the resulting film has significantly greater flexibility and cohesive strength and is extremely useful as a photoresist.

By thoroughly mixing into a solution containing urethane, polymerizable epoxy resin and epoxy curing agent,
It is advantageous to add positive photosensitizers. Photosensitizers are, for example, diazooxides known in the literature, such as naphthoquinone-1,2-diazide (2).
-5-sulfonic acid-p-methylphenyl ester (U.S. Pat. No. 3,046,120, U.S. Pat. No. 3,046,121 and U.S. Pat.
3211553), documents such as U.S. Pat.
2465760, 3113865 and 3661573 and GB 1277428. The photosensitizer must be soluble in the solvent utilized to apply the coating solution. A particularly useful photosensitizer sold under the trade name “Diazo LL” is Molecular
Rearrangement Company (Molecular)
naphthoquinone-(1,2)-diazide-sulfonic acid-(5) available from
- naphthadiester. US Patent No. 4148654
The positive-acting photosensitizers of No. 3 are also useful in the present invention. The positive photosensitizer according to the invention is a substance that decomposes into a more acidic substance than the photosensitizer when exposed to light, especially actinic radiation. Advantageously, the original photosensitizer is neutral or basic in order to provide a significantly greater change in PH. Since the photosensitizer component is incorporated into the mixture of urethane, polymerizable epoxy resin, and curing agent, it is not necessary to provide structural bonding itself. The concentration of photosensitizer is novolac resin
It may be from about 10 parts by weight per 100 parts until the solution is saturated.

The solvent used to form the photosensitive solution is a matter of choice and convenience, such as methyl isobutyl ketone,
Methyl ethyl ketone, etc.

In fact, the solution can simply be coated onto the support material by any known means and then dried at a temperature sufficient to cure the epoxy resin. In the case of a photoresist applied from a transfer film, the film backing contains a release agent thereon, such as methyl cellulose, polyvinylpyrrolidone and a copolymer of methyl vinyl ether and maleic anhydride, to separate the photoresist layer from the film backing. ,
For example, polyester can be easily removed. Following drying, the photoresist composition is heated to a number of substrates such as metals including copper, stainless steel and gold, ceramics, glass, silicon dioxide and organic polymers such as polyimides, epoxy resins and polysiloxanes and polyesters. And it can be easily laminated by applying pressure.

Additionally, the liquid photosensitive solution may be coated onto stainless steel to produce bimetallic printing plates by electrodeposition following imaging and development of the photosensitive material, or the dried composition may be oleophilic in nature. from,
It can be applied to aluminum and silicated aluminum to produce printing plates.

Before coating onto the support, materials such as alkoxysilane coupling agents with epoxy or amine functionality are added to the solution to promote adhesion to the support, e.g. glass, silicon dioxide or other surfaces. can do. Substances of this type are, for example, γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

Depending on the light rays to which the photosensitizer is sensitive, exposure can be carried out in the conventional manner, for example with a carbon arc lamp or the like. The image is developed using a conventional developer, such as a weak alkaline solution, together with the sensitizer used.

Next, the present invention will be explained in detail based on examples.
The present invention is not limited thereto, and "parts" in the examples are "parts by weight" unless otherwise specified.

Example 1 A positive-working composition was prepared by mixing the following ingredients at room temperature: Methyl ethyl ketone 27.6 parts Resinox (trade name for a phenol/formaldehyde resin commercially available from Monsarto) 11.0 parts 2,4,6- Tris (dimethylaminomethyl)
Phenol 0.23 parts DDI-1410, trade name of aliphatic (bridged group having about 36 carbon atoms) diisocyanate commercially available from General Mills Chemicals, Inc. 1.00 parts Contains the above ingredients The solution was stirred until the solution viscosity (measured on a conventional Bruckfield viscometer with a No. 2 spindle) stabilized at approximately 17 centipoise.
Mixed and then added the following ingredients: Methyl ethyl ketone 11.0 parts DER331, Dow Chemical
Epoxy equivalent commercially available from
Trade name of diglycidyl ether of bisphenol A from 186 to 192 3.31 parts Phthalic anhydride 0.26 parts Diaminodiphenylsulfone 0.13 parts 1,2-naphthoquinonediazide-5-p-tert
-butyl phenyl sulfonate 3.6 parts
Knife coat the solution onto a 2 mil thick polyester sheet coated with mg/ ^ft2 , then apply a photosensitive coating.
Dry at 82°C (180°C) for 4 minutes. During drying, the epoxy resin hardened.

The resulting film was sufficiently flexible to withstand mild bending of the support without breaking. This film was heated to 100°C using a heating roll laminating machine.
It was attached to a copper sheet. After lamination, the polyester backing was peeled from the photoresist and the resist was exposed through the original to a carbon arc lamp for 50 seconds. The exposed photoresist was then developed by spraying a 1% aqueous sodium hydroxide solution for 2 minutes.
The exposed copper could be etched or electroplated using conventional industrial methods.

Example 2 A positive-working composition was prepared by mixing 27.7 parts of methyl ethyl ketone, 11.0 parts of Resinox, 0.01 part of 1,4-diazabicyclo(2,2,2)octane, and 1.23 parts of DDI-1410 until the viscosity of the solution stabilized at about 500 centipoise. was manufactured.

Following completion of urethane formation, the following ingredients were added to the solution: DER331 3.0 parts Phthalic anhydride 0.3 parts 1,2-naphthoquinonediazide-5-p-tert
- Butylphenyl sulfonate 3.0 parts After coating, exposing and developing as in Example 1, the film showed excellent flexibility and photoresist properties.

Example 3 A positive composition was prepared by mixing 27.7 parts of methyl ethyl ketone, 11.0 parts of Resinox, 0.06 parts of 1,4-diazabicyclo(2,2,2)octane, and 1.18 parts of DDI-1410 until the viscosity of the solution was stabilized.

The following ingredients were then added to this solution: DER331 2.15 parts Diaminodiphenylsulfone 0.40 parts 1,2-naphthoquinonediazide-sp-tert
After coating, drying, exposing and developing as in Example 1, the film showed good flexibility and photoresist properties.

Example 4 “Resinox” described in Example 1 and DDI-1410
Reaction product with 100 parts DER331 9 parts Diaminodiphenylsulfone 1.7 parts "Diazo LL", a naphthoquinone (1,
2) A photosensitive composition was prepared by mixing 11.6 parts of the trade name of -diazide-(1)-sulfonic acid (5)-naphthodiester and 0.26 parts of γ-aminopropyltriethoxysilane.

Coating the solution onto silicated aluminum,
Dry at 82℃ (180℃). The resulting structure was used as a printing plate. That is, it was imagewise exposed to actinic radiation, developed and inked. The film was found to absorb ink and function as a printing plate.

Example 5 This example demonstrates the advantage of curing Epoquine resin in the presence of polyurethane to form an intertwined binary polymer network.

A positive-working composition was prepared by mixing the following ingredients at room temperature: Acetone 27.6 parts Resinox, a trade name for a phenol/formaldehyde resin commercially available from Monsanto Company.
11.0 parts 2,4,6-tris(dimethylaminomethyl)
Phenol 0.23 parts DDI-1410, trade name of aliphatic diisocyanate commercially available from General Mills Chemicals Co. 1.00 parts A solution containing the above components was measured with a commonly used Burckfield viscometer and the solution viscosity was approximately 15 centipoise. Mixed until stable. This solution was combined with that prepared in the following manner.

Acetone 11.0 parts Epon 828, trade name of diglycidyl ether of bisphenol A with epoxy equivalent weight 186-192, commercially available from Shell Chemical Co. 3.31 parts Phthalic anhydride 0.26 parts Diaminodiphenyl sulfone 0.13 parts Second solution These ingredients were boiled under reflux for 20 hours. To the combined solution was added 3.6 parts of 1,2-naphthoquinonediazide-5-p-tert-butylphenyl sulfonate. After thorough mixing, the combined solution was coated on a 2 mil polyester basecoated with a 50 mg/ft ² coating of methylcellulose or with a 50 mg/ft ² hydrolyzed copolymer made from methyl vinyl ether and maleic anhydride. I applied a knife to it. Photosensitive coating at 82℃ (180℃)
〓) for 4 minutes.

100 using a heating roll laminating machine to film the film
It was laminated to a copper sheet at ℃. Following lamination, the polyester backing was peeled from the photoresist and the resist was exposed to ultraviolet light through a photomask.
The exposed areas of the resist were developed by spraying a 1% aqueous sodium hydroxide solution.

The resists made by this method were inferior to those made by the methods of Examples 1-4. Peeling off the polyester backing was difficult. The quality of the image was poor, with some material leaching from the unexposed resist. The resist was also more brittle than the coatings described in Examples 1-4. However, these coatings were still as good as many used industrially.

Claims (1)

[Scope of Claims] 1 (a) a crosslinked urethane resin formed by the catalytic crosslinking reaction of a non-thermally reactive novolak phenolic resin and a polyisocyanate compound; (b) an epoxy resin having an epoxy equivalent weight of less than about 400 and for use in the epoxy resin. A positive photosensitive composition comprising a curing agent and (c) a positive photosensitizer such as a quinone-based diazooxide. 2. The novolak resin accounts for about 40 to 40% of the composition.
80% by weight, and the concentration of the polyisocyanate is about 6 parts by weight per 100 parts of the novolak resin.
12 parts by weight of the epoxy resin, the concentration of the epoxy resin is from about 20 parts by weight to about 40 parts by weight per 100 parts of the novolak resin, and the concentration of the photosensitizer is at least about 10 parts by weight per 100 parts of the novolak resin. A composition according to claim 1. 3. The novolak resin accounts for about 50 to 50% of the composition.
A composition according to claim 1 containing 70% by weight. 4. The composition of claim 1, wherein the novolac resin is a novolac phenol/formaldehyde resin. 5. The composition of claim 4, wherein said novolac resin has about 500 to about 1000 molecules. 6. The composition according to claim 1, wherein the epoxy resin is diglycidyl ether of bisphenol A. 7. The composition of claim 1, wherein the curing agent is selected from the group consisting of phthalic anhydride, diaminodiphenylsulfone, and mixtures thereof.