JP2611031B2 - Method of forming resist pattern - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a resist pattern, and more particularly, to a method for forming a resist pattern using a transparent thermosensitive recording material as a photomask film used at the time of manufacturing a printed circuit board.

<< Prior Art >> A method of manufacturing a printed circuit board by providing a photosensitive resin layer on a substrate and performing exposure development, etching, and the like through a photomask having a circuit pattern on the layer is well known. As a method of manufacturing a photomask used in this case, a method using the principle of photography is generally used. That is, an original of a circuit pattern is formed, and the original is imaged on a film serving as a main body of a mask and exposed. Thereafter, a mask is finally formed through a process of developing the exposed film and fixing it.

<< Problems to be Solved by the Invention >> However, the production of the above photomask requires time and labor for exposure and development, and is a wet process. However, there was a drawback that it was not possible to form

Such a drawback is a photomask material in which a heat-responsive member whose light transmittance is reduced or improved by rapid cooling or slow cooling after heating and a transparent heat-absorbing member excellent in heat absorption are integrally formed (Japanese Patent Laid-Open No. Sho 63). 177138), but such materials suffered in terms of sensitivity and image duration.

The present inventors have conducted intensive studies to solve the above-mentioned drawbacks, and as a result, it has been found that a heat-sensitive recording material having excellent transparency can be used in place of a photomask film. In addition to being able to perform all dry processes, it is also possible to directly form patterns using digital signals, greatly improving the resist pattern creation process, and from circuit design to the final printed circuit board. The present inventors have found that the process can be carried out, and arrived at the present invention.

Accordingly, a first object of the present invention is to provide an improved method for forming a resist pattern.

A second object of the present invention is to provide a photomask film which does not require wet processing at the time of manufacturing a photomask and can be manufactured using digital signals.

<< Means for Solving the Problems >> The above objects of the present invention are as follows. After forming a photosensitive resin layer on a substrate for a printed circuit board, a photomask film is placed on the resin layer and exposed and developed. In the method for forming a resist pattern, the present invention has been attained by a method for forming a resist pattern, wherein the photomask film is a transparent thermosensitive recording material on which a colored image is formed by heating.

The transparent thermosensitive recording material used in the present invention is a recording material having a transparent thermosensitive layer which develops a color by heating on a transparent support.

In the present invention, a combination of an electron-donating dye precursor and a developer or a combination of a diazo compound and a coupler can be used as a color former that develops color by heating.

As the electron-donating dye precursor used in the present invention, a colorless or pale-colored one is appropriately selected from known compounds which donate electrons or receive a proton such as an acid to form a color. Such a compound has a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, and amide, and these partial skeletons are ring-opened or cleaved upon contact with a developer, and preferred compounds are For example, a triarylmethane compound, a diphenylmethane compound, a xanthene compound, a thiazine compound, a spiropyran compound, and the like can be given.

Particularly preferred compounds are those represented by the following general formula:

In the formula, R ₁ is an alkyl group having 1 to 8 carbon atoms, R ₂ is an alkyl group having 4 to 18 carbon atoms or an alkoxyl group or a tetrahydrofurfuryl group, and R ₃ is a hydrogen atom or a 1 to 15 carbon atoms. An alkyl group or a halogen atom, R ₄ represents a substituted or unsubstituted aryl group having 6 to 20 carbon atoms. As the substituent of R ₄ , an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogenated alkyl group, and a halogen atom are preferable.

As the developer used in the present invention, a color developer that causes a color-forming reaction upon thermal melting with an electron-donating dye precursor can be appropriately used from known ones. For example, as a developer for the leuco dye, a phenol compound, a triphenylmethane compound, a sulfur-containing phenol compound, a carboxylic acid compound, a sulfone compound, a urea or thiourea compound, and the like can be mentioned. For example, in the Pulp and Paper Times (1985), pp. 49-54 and 65-70. Among these, those having a melting point of 50 ° C. to 250 ° C. are particularly preferable, and phenols and organic acids which are hardly soluble in water and have a melting point of 60 ° C. to 200 ° C. are particularly preferable. It is preferable to use two or more developers in combination, since solubility increases.

The amount of the developer used is usually 0.3 to 160 parts by weight, preferably 0.3 to 80 parts by weight, based on 1 part by weight of the electron donating dye precursor.

Particularly preferred among the developers used in the present invention,
It is represented by the following general formulas [I] to [IV].

R ₁ is an alkyl group, an aryl group or an aralkyl group, particularly preferably a methyl group, an ethyl group and a butyl group.

R ₂ is an alkyl group, especially a butyl group, a pentyl group,
Heptyl and octyl are preferred.

R ₃ is an alkyl group or an aralkyl group.

The diazo compound used in another combination of the thermosensitive coloring material according to the present invention is a compound which develops a desired hue by reacting with a coupler described later, and in particular, decomposes upon receiving light of a specific wavelength before the reaction. However, it is preferable to use a photo-decomposable diazo compound which no longer has a color developing ability even when a coupler acts, since light fixing becomes possible. The hue in this color forming system is determined mainly by the diazo dye formed by the reaction between the diazo compound and the coupler. Therefore, as is well known, the color hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupler, and almost any color hue can be obtained depending on the combination. .

The photo-decomposable diazo compound in the present invention mainly means an aromatic diazo compound. Specifically, it refers to an aromatic diazonium salt, a diazosulfonate compound, a diazoamino compound and the like.

The coupler used in combination with the diazo compound dissolved in the present invention is a compound that forms a dye by coupling with a diazo compound (diazonium salt).

Specific examples thereof include, for example, 2-hydroxy-3-
In addition to naphthoic acid anilide,
There can be mentioned those described in JP-A-62-146678.

Further, an image of any color tone can be obtained by using two or more of these couplers. Since the coupling reaction between the diazo compound and the coupler easily occurs in a basic atmosphere, a basic substance may be added to the layer.

As the basic substance, a water-insoluble or water-insoluble basic substance or a substance that generates an alkali by heating is used. Examples thereof include inorganic and organic ammonium salts, organic amines, amides, ureas and thioureas and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. , Morpholines,
Examples include nitrogen-containing compounds such as piperidines, amidines, formazines, and pyridines. Specific examples of these are described in, for example, JP-A-61-291183.

 Two or more basic substances may be used in combination.

In the present invention, the viewpoint of raw preservability such as preventing contact of materials involved in color development at room temperature (fogging prevention),
From the viewpoint of controlling color development sensitivity such as color development with desired applied heat energy, it is preferable to use a part of components essential for color development encapsulated.

The type of microcapsules used in this case is not particularly limited, but particularly preferred microcapsules in the present invention are: normal temperature prevents the contact of substances inside and outside the capsule due to the substance-isolating action of the microcapsule wall; It is preferable that the permeability of the substance is increased only during the heating. In this case, the permeation start temperature can be freely controlled by appropriately selecting the capsule wall material, the capsule core substance, the additives, and the like. The permeation start temperature in this case corresponds to the glass transition temperature of the capsule wall (eg, JP-A-59-91438).

In order to control the glass transition point inherent in the capsule wall, it is necessary to change the type of the capsule wall forming agent.

Polyurethane, as the wall material of the microcapsule,
Polyurea, polyester, polycarbonate, urea
Formaldehyde resin, melamine resin, polystyrene,
Styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like can be mentioned, and two or more of these polymer substances can be used in combination.

In the present invention, among the above polymer substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The microcapsules used in the present invention are obtained by emulsifying a core material containing one of components (hereinafter, collectively referred to as a color forming agent) directly involved in a coloring reaction, and then forming a wall of a polymer material around the oil droplets. It is preferred to microencapsulate, in which case the reactant forming the polymeric substance is added inside the oil droplets and / or outside the oil droplets.

Here, the organic solvent for forming the oil droplets can generally be appropriately selected from high-boiling oils. In particular, when an organic solvent having excellent solubility in a color former is used, thermal printing is performed. In this case, the color density and the color forming speed can be increased, and the capri can be reduced.

When making microcapsules, they can be made from emulsions containing 0.2% by weight or more of the component to be microencapsulated.

It is preferable to use 0.1 to 10 parts by weight of the coupler and 0.1 to 20 parts by weight of the basic substance with respect to 1 part by weight of the diazo compound. On the other hand, the developer is used in an amount of 0.3 to 160 parts by weight, preferably 0.3 to 8 parts by weight, based on 1 part by weight of the electron donating dye precursor.
It is preferable to use 0 parts by weight.

In the case of using the preferred microcapsules produced as described above, the reactive substance contained in the core and outside of the microcapsules can permeate through the microcapsule wall and react to form a dye only during heating printing. it can.

 In the present invention, a coloring aid can be used.

The color-forming aid that can be used in the present invention is a substance that increases the color density at the time of heating printing or lowers the minimum color-forming temperature, lowers the melting point of a basic substance or a color-forming agent,
The purpose is to create a situation where the diazo compound, the basic substance, the coupler, the electron-donating dye precursor, the color developer and the like are easily reacted by the action of lowering the softening point of the capsule wall.

Examples of the coloring aid include phenol compounds, alcoholic compounds, amide compounds, and sulfonamide compounds. Specific examples include p-tert-octylphenol,
p-benzyloxyphenol, phenyl p-oxybenzoate, benzyl carbanilate, phenethyl carbanilate, hydroquinone, dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-methanesulfonic acid amide, N-phenyl-methanesulfonic acid amide, etc. Can be mentioned. These may be contained in the core material or may be added as a dispersion outside the microcapsules.

In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, and the like can be added as an acid stabilizer.

In the present invention, in order to make the heat-sensitive recording layer transparent, a developer or a coupler is dissolved in an organic solvent that is hardly soluble or insoluble in water, and then the surfactant is added to the protective colloid containing a water-soluble polymer. A dispersion obtained by mixing and emulsifying and dispersing with an aqueous phase having the above (for example, JP-A-63-392489) is used.

The organic solvent that dissolves the color developer or coupler can be appropriately selected from high-boiling oils. Among them, preferred oils include, in addition to esters, compounds represented by the following general formulas (V) to (VII), triallylmethane (for example, tritolylmethane, toluyldiphenylmethane), and terphenyl compounds (for example, terphenyl) ), Alkylated diphenyl ethers (eg, propyl diphenyl ether, hydrogenated terphenyl (eg, hexahydroterphenyl), diphenyl ether, etc.).

In the present invention, among these, the use of esters is particularly preferable from the viewpoint of solubility of the color developer and emulsification stability of the emulsified dispersion of the color developer.

In the formula, R ¹ is hydrogen or an alkyl group having 1 to 18 carbon atoms, R ²
Represents an alkyl group having 1 to 18 carbon atoms. p ¹ and q ¹ are 1 to
Represents an integer of 4, and the total number of alkyl groups is within four.

It is preferable alkyl groups of R ¹ and R ² is an alkyl group having 1 to 8 carbon atoms.

In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms,
R ⁴ represents an alkyl group having 1 to 12 carbon atoms, and n represents 1 or 2.

It represents an integer of p ² and q ² 1 to 4. If n = 1,
The total number of the alkyl groups is 4 or less, and when n = 2, the total number of the alkyl groups is 6 or less.

In the formula, R ⁵ and R ⁶ represent a hydrogen atom or a same or different alkyl group having 1 to 18 carbon atoms. m represents an integer of 1 to 13. p ³ and q ³ represent an integer of 1 to 3, and the total number of the alkyl groups is 3 or less.

Incidentally, it is particularly preferred alkyl group for R ⁵ and R ⁶ is an alkyl group having 2 to 4 carbon atoms.

Examples of the compound represented by the formula (V) include dimethylnaphthalene, diethylnaphthalene, and diisopropylnaphthalene.

Examples of the compound represented by the formula (VI) include dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl and diisobutylbiphenyl.

Examples of the compound represented by the formula (VII) include 1-methyl-1-dimethylphenyl-1-phenylmethane and 1-methyl-1-dimethylphenyl-1-phenylmethane.
Ethyl-1-dimethylphenyl-1-phenylmethane,
1-propyl-1-dimethylphenyl-1-phenylmethane is exemplified.

Examples of esters include phosphate esters (for example, triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, cresyl diphenyl phosphate), phthalate esters (dibutyl phthalate, 2-ethylhexyl phthalate,
Ethyl phthalate, octyl phthalate, butyl benzyl phthalate) Dioctyl tetrahydrophthalate, benzoic acid ester (benzoic acid ester, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietic acid ester (ethyl abietic acid) , Benzyl abietic acid), dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalate (dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleate (dimethyl maleate, diethyl maleate, dibutyl maleate) ), Tributyl citrate, sorbate (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate (dibutyl sebacate, dioctyl sebacate), ethylene glycol Glycol ester compounds (formic acid monoesters and diesters, butyric acid monoesters and diesters,
Lauric acid monoester and diester, palmitic acid monoester and diester, stearic acid monoester and diester, oleic acid monoester and diester), triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, borate (tributyl borate) , And tripentyl borate). Among these, when tricresyl phosphate is used alone or as a mixture, the emulsification and dispersion stability of the color developer or the coupler is particularly good, which is preferable.

In the present invention, an auxiliary solvent may be further added to the above-mentioned organic solvent as a low boiling point dissolution aid. As such co-solvents, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

A water-soluble polymer to be contained as a protective colloid in an aqueous phase mixed with an oil phase in which a developer or a coupler is dissolved is:
It can be appropriately selected from among known anionic polymers, nonionic polymers and amphoteric polymers, but polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferred.

Further, as the surfactant to be contained in the aqueous phase, from the anionic, nonionic or amphoteric surfactants, those which do not cause precipitation or aggregation by acting with the protective colloid described above are appropriately used. Can be. Preferred surfactants include sodium alkylbenzenesulfonate (eg, sodium dodecylbenzenesulfonate), sodium alkyl sulfate, sodium dioctyl sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether), and the like. .

The emulsified dispersion of the color developer or the coupler in the present invention,
An oil phase containing a developer or a coupler and an aqueous phase containing a protective colloid and a surfactant are mixed and dispersed using a means commonly used for fine particle emulsification such as high-speed stirring and ultrasonic dispersion to easily obtain. be able to.

To this emulsified dispersion, a color developer and a melting point depressant for a coupler can be added as appropriate. Some of such melting point depressants also have the function of controlling the glass transition point of the capsule wall. Such compounds include, for example, hydroxy compounds, carbamic acid ester compounds, sulfonamide compounds, aromatic methoxy compounds and the like, the details of which are described in, for example, Japanese Patent Application No. 59-244190.

These melting point depressants are developer 1 that lowers the melting point.
0.1 to 2 parts by weight, preferably 0.5 to 1 part by weight, can be used as appropriate. However, a melting point depressant and a developer or a coupler whose melting point is lowered by the same are used in the same place. Is preferred. When it is added to a different portion, it is preferable to add 1 to 3 times the above amount.

The heat-sensitive recording material of the present invention can be coated using a suitable binder.

Examples of the binder include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylate, and ethylene-vinyl acetate copolymer. And other various emulsions can be used. The amount used is 0.5 to 5 g / m ² as solid content.

The heat-sensitive recording material of the present invention contains a microcapsule containing an electron-donating dye precursor or a diazo compound and a dispersion obtained by emulsifying and dispersing at least a color developer or a coupler, and a coating solution containing other additives such as a binder to prepare a coating solution. Coating and drying by a coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, etc. on the transparent synthetic resin film support, the solid content is 2.5 to 25 g / m ^2. It is manufactured by providing a heat-sensitive layer.

The heat-sensitive layer of the heat-sensitive material thus produced has extremely good transparency.

In the present invention, a layer containing microcapsules containing the electron-donating dye precursor or diazo compound used in the heat-sensitive layer may be further provided on the transparent heat-sensitive layer. In this case, an emulsified dispersion of a color developer or a coupler can be further contained as required, but the amount thereof must be 20% by weight or less based on the total weight of the layer. By providing a layer having a small amount of the developer emulsified dispersion in this way, the adhesiveness of the present thermosensitive recording material can be reduced, and
Since the electron-donating dye precursor contained in this layer can also contribute to color development, providing this layer does not lower the thermal sensitivity.

In the present invention, in the heat-sensitive layer, silica, barium sulfate, titanium oxide, aluminum hydroxide, for the purpose of preventing sticking to the thermal head and improving writability.
Pigments such as zinc oxide and calcium carbonate, and fine powder such as styrene beads and urea-melamine resin can be added, but in order to maintain the transparency of the heat-sensitive layer, it is mainly stored and safe on the heat-sensitive layer. It is preferable to provide a protective layer for the purpose of property by a known method and to add the protective layer to the protective layer. Details of the protective layer are described, for example, in "Paper Pulp Technical Times" (September 1985, pp. 2-4).

In particular, when a protective layer containing a combination of silicon-modified polyvinyl alcohol and colloidal silica as a main component is used, the transparency of the protective layer becomes extremely good, and the transparency of the heat-sensitive recording material can be significantly improved. preferable.

Waxes and metal soaps can be added to the protective layer to prevent sticking. Their usage is between 0.2 and 7 g / m ² .

Examples of the wax include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide, ethylenebisstearamide, and higher fatty acid ester.

Examples of the metal soap include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

Further, the coating amount of thermosensitive layer ^{3g / m 2 ~20g / m 2} , in particular 5 g / m ² to 15
It is preferably between g / m ² . If it is 3 g / m ² or less, sufficient sensitivity cannot be obtained, and even if it is applied at 20 g / m ² or more, no improvement in quality can be seen, which is disadvantageous in cost.

The transparent synthetic resin film used as the support has abrasion resistance,
A known water-resistant and chemical-resistant material having a thickness and / or rigidity that does not cause curling due to application of a heat-sensitive layer, does not deform even when heated during the development process, and has dimensional stability. It can be arbitrarily selected from materials. As such a film, a polyester film such as polyethylene terephthalate or polybutylene terephthalate,
Cellulose derivative film such as cellulose triacetate film, polystyrene film, polypropylene film,
Examples thereof include polyolefin films such as polyethylene, and these can be used alone or in combination.

The thickness of the support is preferably from 20 to 200 μm, particularly preferably from about 50 to 100 μm.

In the present invention, an undercoat layer can be provided between the plastic film and the heat-sensitive layer in order to enhance the adhesion between the two layers. As a material for the undercoat layer, gelatin, rigid polymer latex, nitrocellulose, or the like is used. The coating amount of the undercoat layer is preferably in the range of ^{0.1g / m 2 ~2.0g / m 2} , preferably in the range particularly ^{0.2g / m 2 ~1.0g / m 2} . 0.1g / m ²
If less, the adhesion between the film and the heat-sensitive layer is not enough,
Further, even if the film thickness is increased to 2.0 g / m ² or more, the adhesive force between the film and the heat-sensitive layer has reached saturation, which is disadvantageous in cost.

The undercoat layer may be swelled by the water contained in the heat-sensitive layer when the heat-sensitive layer is applied thereon,
It is desirable to cure using a hardener.

As the hardener, dialdehydes such as glutaraldehyde, 2,3-dihydroxy-1,4-dioxane and boric acid are preferred.

The addition amount of these hardeners is in the range of 0.20% by weight to 3.0% by weight based on the weight of the undercoat material, and an appropriate addition amount can be selected according to the application method and the desired degree of curing.

Further, an antifoaming agent can be added to eliminate bubbles generated at the time of application, or an activator can be added to improve the leveling of the liquid and prevent the generation of coating streaks.

Further, if necessary, an antistatic agent can be added.

Furthermore, before applying the undercoat layer, it is desirable to activate the surface of the film by a known method. As the method of the activation treatment, an etching treatment with an acid, a flame treatment with a gas burner, or a corona treatment, a glow discharge treatment, or the like is used.From the viewpoint of cost or simplicity, U.S. Pat. No. 2,846,727, No. 3,
No. 549,406 and No. 3,590,107 are most preferably used.

In the present invention, a back layer may be provided on the back surface of the support for the purpose of curling, preventing static charge, and improving slipperiness.
As the constituent components of the back layer, it is preferable to use the same components as those of the protective layer.

The coating solution according to the present invention is a well-known coating method, for example, a dip coating method, an air knife coating method,
It can be applied by a curtain coating method, a roller coating method, a doctor coating method, a wire bar coating method, a slide coating method, a gravure coating method, or an extrusion coating method using a hopper described in U.S. Patent No. 2,681,294. I can do it. If necessary, U.S. Pat.Nos. 2,761,791, 3,508,947, 2,941,898,
It is also possible to apply two or more layers at the same time by the method described in, for example, the method described in Yuki Harasaki, “Coating Engineering”, p. 253 (published by Asakura Shoten in 1973), and the like, the specification of No. 3,526,528, and the coating can be performed simultaneously. An appropriate method can be selected according to the application speed and the like.

Further, in the coating liquid, a pigment dispersant, a thickener, a flow modifier,
An antifoaming agent, an antifoaming agent, a release agent, and a coloring agent can be appropriately compounded as needed.

In the present invention, a circuit pattern is formed on the transparent thermosensitive recording material obtained as described above using a thermal head, a laser beam, or the like. Particularly when a combination of a diazo compound and a coupler is employed as a color former,
After forming the pattern, it is preferable to irradiate the entire surface of the thermosensitive recording material with ultraviolet rays to decompose the diazo compound in the non-image area, thereby fixing the circuit pattern.

Using the circuit pattern of the transparent thermosensitive recording material obtained as described above as a photomask, a resist pattern can be formed according to a conventional method.

<< Effect of the Invention >> As described in detail above, since the photomask used in the present invention is a heat-sensitive recording material, not only can the mask be prepared in a dry manner, but also it is possible to directly form a pattern from a digital signal. Can be. Therefore, not only from the viewpoint of eliminating the need for wet work in the conventional photomask making process, but also the photomask making is greatly simplified, so that the method of forming a resist pattern itself is also greatly improved.

<< Example >> Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1. A photosensitive resin film (VANXA450, manufactured by Fuji Photo Film Co., Ltd.) was bonded to a through-hole plated copper-clad laminate, and a transparent heat-sensitive film prepared by the following method was prepared by a CAD computer. The image was printed out and superimposed as a photomask, an etching resist pattern was formed by exposure and development, and then a circuit was formed by etching.

The obtained circuit was of good quality without disconnection or conduction.

(Preparation of capsule liquid)

Leuco dye represented by the following structural formula 20 g of Takenate D-110N (capsule wall material manufactured by Takeda Pharmaceutical Co., Ltd.) was added and dissolved in a mixed solvent of 12 g of 1-phenyl-1-xylylethane and 20 g of methylene chloride.
The solution of this leuco dye was applied to PVA217C (Kuraray Co., Ltd.)
The mixture was mixed with 60 g of an 8% aqueous solution of polyvinyl alcohol and 20 g of ion-exchanged water using ion-exchanged water, emulsified at 10,000 rpm for 5 minutes with an ace homogenizer manufactured by Nippon Seiki Co., Ltd. Then, the mixture was reacted at 40 ° C. for 3 hours to produce a capsule liquid having a capsule size of 1.0 μm. The above Kuraray PVA217C has a reduced amount of sodium ions.

(Preparation of developer emulsified dispersion)

5 g of the developers (a), 2 g of (b) and 8 g of (c) represented by the following structural formula were dissolved in 1 g of 1-phenyl-1-xylylethane and 7 g of ethyl acetate. The obtained developer solution was added to PVA2
37 g of 8% aqueous solution of polyvinyl alcohol using 17C and ion-exchanged water, 35 g of ion-exchanged water, and triethanolamine dodecylbenzenesulfonate (surfactant) 0.
The mixture was mixed with 2 g of an aqueous solution, and emulsified at 10,000 rpm at room temperature for 5 minutes using an ace homogenizer manufactured by Nippon Seiki Co., Ltd. to obtain an emulsified dispersion having a particle size of 1.5 μm.

[Preparation of heat-sensitive recording material] 5.0 g of the above capsule liquid, 10.0 g of a developer emulsified dispersion and 5.0 g of ion-exchanged water were stirred and mixed, and a transparent polyethylene terephthalate (PET) support having a thickness of 75 µm was formed on one surface of the support. A solid content is applied to 6 g / m ² and dried to form a heat-sensitive layer, and then a protective layer having the following composition is solidified on the heat-sensitive recording layer using ion-exchanged water at a solid content of 2.5 g / m2. ² was applied. The aqueous dispersion of kaobrite was subjected to an ion exchange treatment with an ion exchange resin Urbanlite MB3 (manufactured by Organo Corporation).

Polyvinyl alcohol (PVA217C manufactured by Kuraray Co., Ltd.) 2 parts by weight Caoblite (Thiele) 4 parts by weight Boric acid 0.1 part by weight Zn stearate dispersion (manufactured by Chukyo Yushi Co., Ltd.) 0.2 parts by weight Ammonium lauryl sulfate 0.05 parts by weight obtained When the transparent thermosensitive recording material was measured with a Macbeth transparent densitometer (visible range), the transmittance at a wavelength of 360 nm was 9
0%, and the maximum color density was 1.53.

Claims (2)

(57) [Claims] 1. A method for forming a resist pattern, comprising: forming a photosensitive resin layer on a substrate for a printed circuit board; placing a photomask film on the resin layer; exposing and developing the resist pattern; A method for forming a resist pattern, which is a transparent thermosensitive recording material on which a color image is formed by heating. 2. The method for forming a resist pattern according to claim 1, wherein the transmittance of the transparent thermosensitive recording material at a wavelength of 360 nm is 70% or more and the maximum color density is 1.0 or more.