JPS6227736A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To form a uniform photosensitive resin layer on a printed circuit board and to improve resolution by irradiating active rays on a coated surface of a substrate via a pattern mask held in tight contact with a flexible base side while pressing said surface under the specified pressure with the endless and transparent flexible base to be repeatedly used then recovering the coating and developing the same. CONSTITUTION:The photosensitive resin 1 is coated on the printed circuit board 4 to the uniform specified film thickness by a coating machine 3 under rotation at a specified speed to form the photosensitive resin layer 5. The printed circuit board 4 coated with the photosensitive resin 1 is carried by a conveyor belt 7 in a specified direction and is thereafter pressed under the specified pressure by the endless and transparent flexible base 8. The printed circuit board 4 is further irradiated with the active rays onto the photosensitive resin layer 5 on the printed circuit board 4 through the pattern mask 17 in tight contact with the top of the flexible base 8 from above the repeatedly usable flexible base 8 by an exposing machine 16 such as high pressure mercury lamp. The uncured photosensitive resin on the flexible base 8 is recovered as a recovered photosensitive resin 20 by a photosensitive resin recovering device 19 and is reused.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention involves applying a liquid photosensitive resin or a liquid photosensitive resin composition onto a substrate such as a printed circuit board to a certain thickness, and then exposing a predetermined portion to light. The present invention relates to a method for forming a resist pattern suitable as a solder mask, which is developed and forms a cured product of a liquid photosensitive resin or a liquid photosensitive resin composition on the substrate.

[Conventional technology]

Conventionally, resist patterns such as solder masks have been created by laminating a photosensitive resin or photosensitive resin composition (hereinafter sometimes simply referred to as "photosensitive resin") on a printed circuit board, and curing predetermined portions with light. After that, only the uncured portion is removed by development.

There are two types of photosensitive resins used for resist patterns such as solder masks: circumferential and liquid.

Solid photosensitive resins are usually produced by preparing a photosensitive resin solution dissolved in a specific solvent before use, coating this on a specific support, and then drying it to form a substantially solid sheet or Used in film form.

Since such a solid photosensitive resin sheet or film is solid, it is characterized by excellent workability and work environment friendliness.

However, applying a solution of a photosensitive resin to a specific support and drying it to prepare a sheet or film-like photosensitive element, then laminating the sheet or film again on a printed circuit board, is not possible. In the production process for producing the sheet or film-like photosensitive nitrous film, organic solvents are generally used, which poses problems in terms of poor working environment and in terms of the number of steps.

On the other hand, liquid photosensitive resin is an excellent resist pattern formation method in terms of the number of steps because it is directly coated in a liquid state onto a printed circuit board immediately before use.

In addition, since it is a liquid, it is generally possible to form an excellent resist pattern even on highly uneven substrates. Suitable as a resin.

However, since the liquid photosensitive resin is in a liquid state, it has the disadvantage that if the liquid photosensitive resin is applied onto a printed circuit board and then exposed with a pattern mask in close contact with the coating surface, the mask will become dirty.

As a method to solve this mask stain, JP-A-58-2
No. 4144 and No. 59-16396,
A liquid photosensitive resin is applied to a uniform thickness on a transparent flexible support that transmits actinic rays, and the flexible support is immediately moved to coat the surface coated with the liquid photosensitive resin on a printed circuit board. A method for forming a solder mask includes laminating the liquid photosensitive resin to a constant thickness on the printed circuit board by pressing with a constant pressure toward the substrate, exposing it to light, peeling off the flexible support, and developing it. Disclosed.

In this method, since the photosensitive resin is in a liquid state, most of the uncured photosensitive resin layered on the printed circuit board is removed when the flexible support is peeled off after exposure. It adheres to a flexible support using its own adhesive strength and is recovered and reused.

Therefore, the amount of loss due to uncured photosensitive resin being dissolved in the developer is small, and because the amount of developer used is also small, it is easy to dispose of the developer after use. Has characteristics.

However, according to this method, after applying a liquid photosensitive resin to a uniform thickness on a transparent flexible support, when pressing it with a constant pressure toward the printed circuit board, the unevenness of the printed circuit board is created. This causes air bubbles to be trapped in the resist pattern, causing problems such as bubbles forming in the resist pattern and causing swelling and peeling during soldering. There is also the problem that resin easily penetrates.

[Problem that the invention seeks to solve]

As mentioned above, the technical issues when using liquid photosensitive resin are to form a coating film with a predetermined uniform thickness without bubbles on the printed circuit board, and the printed circuit board has many through-holes. The problem is to prevent the liquid photosensitive resin from entering the through-hole portion, and to find a method for exposing the surface of the coating film by bringing the pattern mask into close contact with the surface, which is the conventional exposure method.

For example, if a liquid photosensitive resin is not uniformly applied to a printed circuit board, the boundaries between exposed and unexposed areas will not be clear, making it impossible to form a resist pattern with high resolution.

Furthermore, if photosensitive resin remains in the through-hole area after development, soldering cannot be performed accurately, resulting in defects in electrical conductivity between the electronic parts mounted on the printed circuit board and the conductor parts on the printed circuit board. Unable to complete a satisfactory circuit.

The present invention was made against the background of these conventional technical problems, and it is possible to form a uniform photosensitive resin layer on a printed circuit board, and therefore a resist pattern with high resolution can be formed with good reproducibility. , a resist pattern that does not stain the pattern mask with photosensitive resin, is economical because the transparent flexible support can be used repeatedly, and furthermore, uncured photosensitive resin can be easily recovered. The purpose is to provide a method for forming.

[Means for solving problems]

That is, in the present invention, a liquid photosensitive resin or a liquid photosensitive resin composition is applied onto a substrate to a uniform thickness, and then the coated surface of the substrate is coated with an endless transparent flexible support that is used repeatedly. Actinic light is irradiated through a patterned mask that is in close contact with the flexible support while pressing at a constant pressure, and then the flexible support is peeled off to remove the uncured liquid that has adhered to the support. The present invention provides a method for forming a resist pattern, which comprises collecting a photosensitive resin or a liquid photosensitive resin composition and developing a photosensitive resin layer or a photosensitive resin composition layer on a substrate.

The present invention first coats a substrate such as a printed circuit board with a liquid photosensitive resin to a constant thickness, and then moves the substrate coated with a uniform thickness in a constant direction to create an endless film that can be used repeatedly. While pressing the coated surface of the substrate with a constant pressure using a transparent flexible support, a pattern mask is brought into close contact with the support, and actinic light is irradiated through the pattern mask to form a latent image of the resist pattern. The uncured photosensitive resin deposited on the flexible support is recovered by forming the flexible support and then peeling the flexible support from the substrate, while developing the photosensitive resin layer remaining on the printed circuit board. It is.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a configuration diagram of a resist pattern forming apparatus for forming a solder mask on a printed wiring circuit board, which is an embodiment for explaining the resist pattern forming method of the present invention.

To explain FIG. 1, the photosensitive resin 1 is stored in a coating (coating) pan 2 and coated with a coating machine 3 consisting of a roll rotating at a constant speed to form a film with a constant thickness.
The photosensitive resin is then placed on the printed circuit board 4 again to form a photosensitive resin layer 5.

The photosensitive resin layer 5 formed by the coating machine 3 is exposed to active light such as violet rays through a pattern mask 17 to form a photosensitive resin layer 6 after exposure.

Further, a conveyor belt 7 for conveying the printed circuit board 4 is disposed along the direction in which the printed circuit board 4 travels.

Following the coating machine 3 along the traveling direction of the conveyor belt 7, a transparent flexible support 8 consisting of an endless belt is provided with a pressure feed roll 9, a feed roll 10, a peeling roll (combined feed roll) 11, It is stretched around the tension rolls 12 and 13 and is rotatable along the traveling direction of the conveyor belt.

Note that this flexible support 8 is a transparent material that transmits actinic rays, has adhesiveness to uncured photosensitive resin, and has releasability to cured photosensitive resin. Materials with flexibility (e.g. wavelength of 300 to 500 nm)
(polyethylene terephthalate, polypropylene, etc.) with good light transmittance.

Further, the pressure roll 9 is adjusted to an appropriate pressure so that the surfaces of the photosensitive resin layer 5 on the printed circuit board 4 and the flexible support 8 are brought into sufficient contact with each other.

Further, the tension rolls 12 and 13 are used to apply appropriate tension to the flexible support 8 itself so that the flexible support 8 does not wrinkle or loosen. Can be used repeatedly over a long period of time.

The printed circuit board 4 leaving the flexible support 8 along the conveyor belt 7 is adapted to be transported by transport rolls 14 and 15 to a developer chamber (not shown).

Further, an exposure machine 16 is disposed within the stretched flexible support 8 facing the printed circuit board 4 sent along the conveyor belt 7, and a photosensitive resin of the exposure machine is disposed. A pattern mask 17 is fixed to one end close to the layer 5 and the flexible support 8 via an actinic ray shielding plate 18 .

Furthermore, a photosensitive resin recovery device 1 is installed on the outer periphery of the flexible support 8.
9 is attached so that the uncured photosensitive resin 20 adhering to the flexible support 8 can be recovered.

In addition, in front of the exposure machine 16, a release agent applicator 21 is installed so that a release agent can be applied in advance to the pattern mask contact surface of the flexible support 8 as needed. This allows the flexible support to be used for long periods of time without any stains.

Thus, according to FIG. 1, the photosensitive resin 1 is coated (coated).
The resin 1, which is stored in a pan 2, is coated onto a printed circuit board 4 with a constant uniform thickness by a coating machine (or coating machine) 3 rotating at a constant speed, thereby forming a photosensitive resin layer. (
The printed circuit board 4, which has been coated with a photosensitive resin (coated surface) 5, is conveyed in a certain direction by a conveyor belt 7, and then transferred under a constant pressure by an endless transparent flexible support 8. usually,
0.1-15 kg/c+o, preferably 1-10 kg
/c11 is pressed.

Furthermore, the printed circuit board 4 sent in the same direction by the conveyor belt 7 is transferred from above to a flexible support 8 that can be used repeatedly in an exposure machine 16 such as a high-pressure mercury lamp.
The photosensitive resin IW 5 on the printed circuit board 4 is coated with a photosensitive resin with a wavelength of, for example,
Actinic light of 00 to 500 nm is irradiated.

After being irradiated with the required amount of actinic light, the printed circuit board 4 passes through feed rolls 14 and 15 and is transferred to a developing chamber (not shown).
be carried to.

In the present invention, the developing method is not particularly limited, and for example, a dip method, a dip swing method, a one-way spray method, etc. may be used, but a one-way spray method is preferable.

The flexible support 8 covering the photosensitive resin layer 5 on the printed circuit board 4 is peeled off from the coated surface (photosensitive resin layer 6) after exposure by a peeling roll 11, and then removed by tension rolls 12 and 13 and pressure. It passes through the feed roll 9 and is used repeatedly to cover the photosensitive resin layer 5 on the printed circuit board 4 again.

Here, the flexible support 8 that has been peeled off from the coating surface has releasability to the cured product of the photosensitive resin as described above,
Since the uncured photosensitive resin has adhesive properties, the uncured photosensitive resin peels off from the coated surface of the substrate and adheres to the support.

The uncured photosensitive resin on the flexible support 8 is thus recovered as recovered photosensitive resin 20 by the photosensitive resin recovery device 19 and reused.

In this way, most of the uncured photosensitive resin is collected by adhering to the flexible support 8, so that the rate of contamination of the developer during the development process is significantly reduced.

In the apparatus shown in Figure 1, the apparatus is arranged to form a resist pattern on one side of the printed circuit board, but by combining two sets of apparatuses shown in Figure 1, both sides of the printed circuit board can be photosensitive simultaneously. A resist pattern can also be formed by applying a resin and exposing it to light.

Furthermore, as is clear from the forming method shown in FIG.
In the present invention, since the photosensitive resin is first applied onto the substrate, a coating film of uniform thickness can be obtained, and when the substrate coated with the photosensitive resin is pressed with a flexible support, Since there is no air entrainment, and the flexible support itself is composed of an endless heald, it can be used repeatedly, and the uncured photosensitive resin can also be recovered.

The liquid photosensitive resin applied to the present invention may be any type, but preferably (A) a photopolymerizable compound 3 having at least one terminal ethylenically unsaturated double bond.
0 to 90%, (B) photopolymerization initiator 0.001 to 15
01-15 Seiyo (C) α, β-ethylenically unsaturated carboxylic acid 1-25% by weight, monoolefinically unsaturated compound 5
Copolymer 5-70 consisting of ~20% by weight and 55-94% by weight of α,β-ethylenically unsaturated carboxylic acid ester
Examples include liquid photosensitive resin compositions that can be developed with a developer consisting of an alkaline aqueous solution containing % by weight.

Here, as the photopolymerizable compound (component A) having at least one terminal ethylenically unsaturated double bond, esters of acrylic acid or methacrylic acid of monohydric or polyhydric alcohols; for example, ethylene glycol diacrylate, ethylene Glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, Glycerin triacrylate, glycerin trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane triacrylate, trimethylolethane trimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, sorbitol hexaacrylate, sorbitol Hexamethacrylate, sorbitol pentaacrylate, sorbitol pentamethacrylate, etc.
Acrylamides or methacrylamides; for example, methacrylamide, methylenebisacrylamide, acrylamide or methacrylamide of monoamines or polyamines; ■Allyl compounds; for example, malonic acid, oxalic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid,
Diallyl esters of dicarboxylic acids such as terephthalic acid, hexahydrophthalic acid and chlorendic acid, diallyl esters of disulfonic acids such as triallyl trimellitate, hesodisulfonic acid and naphthalenedisulfonic acid, diallylamine, N,N'-diallyl oxalic acid diamide, 1.3-
Diallylurea, diallyl ether, etc.; ■Polyvinyl compounds; For example, divinylbenzene, p-allylstyrene,
p-isopropenyl styrene, divinyl sulfone, ethylene glycol divinyl ether, glycerol trivinyl ether, divinyl succinate, divinyl phthalate, divinyl terephthalate, etc. ■Ethylenically unsaturated compounds co-containing epoxy; for example, glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether , croton glycidyl ether, maleic acid monoalkyl ester monoglycidyl ester, etc. Acrylic acid or methacrylic acid ester compounds having an ionic group; for example, 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride, methacryloyloxyphenyltrimethylammonium chloride, etc. , (2) Photopolymerizable monomers or oligomers that are generally commercially available; for example, Aronix M5700, M6100, manufactured by Toagosei Chemical Industry (2). M8O30, M2B5, M
2O3, M215, M315, M325, etc. acrylate or methacrylate thread thread 1 NK ester 2G, 4G, 9G, ABPE-4, A manufactured by Shin Nakamura Chemical Industry ■
-Acrylate or methacrylate seven-mer 1 such as TMPT, U-4HASCB-1, CBXπ1 manufactured by Nippon Kayaku ■, KAYARAD R601, DPCA-30
, DPCA-66, KAYAM E RPM-
1. Acrylate or methacrylate monomer such as PM-2, manufactured by San Nobuco, Photomer 4061.5
Acrylate or methacrylate monomers such as 007, manufactured by Showa Kobunshi, Lipoxy VR60, VR90
, 5P1509 and other epoxy acrylates or epoxy methacrylates, manufactured by the same company, Subirasoku E-4000
X.

A spirane resin having a spiroacecool structure such as U3000 and an acrylic group or a methacrylic group can be used.

These compounds of component A may be used alone or in a mixture of two or more.

The amount of component A added is 30 to 95% by weight, preferably 50% by weight.
~90% by weight. If the amount of component A added is less than 30% by weight, a liquid photosensitive resin composition with good coating properties cannot be obtained, and the photocurability of the composition decreases, resulting in poor solvent resistance and mechanical properties of the photocured product. It is not possible to sufficiently increase the target strength.

On the other hand, if the amount added to the ingredients exceeds 95% by weight,
This results in a decrease in cooling impact resistance and solvent resistance.

Next, as the photopolymerization initiator (component B), α-diketones such as benzyl and acetyl, which are usually used as reaction initiators, acyloins such as benzoin, benzisodimethyl ether, hendiisodiethyl ether, and benzisopropyl ether acyloin ethers such as
Thioxanthone, 2,4-diethylthioxanthone, thioxanthone-1-sulfonic acid, thioxanthone-4-
Thioxanthone such as sulfonic acid, benzophenone,
Hensiphenones such as 4,4'-dimethylaminobenzophenone (Michler's ketone), acetophenone, p
- Acetophenones such as dimethylaminoacetophenone, α, α′-dimethoxyacetoxyacetophenone, p-methoxyacetophenone, anthraquinone, 1,4
- Examples include quinones such as naphthoquinone.

These compounds of component B may be used alone or in a mixture of two or more.

The amount of component B added is 0.001 to 15% by weight, preferably 0.001 to 15% by weight. It is 5 to 10% by weight. Addition amount of component B is 0.0
If the amount is less than 1% by weight, the liquid photosensitive resin composition will not be able to provide sufficient curability, while if it exceeds 15% by weight, all the photopolymerization initiator will be involved in the reaction during photocuring. As a result, the storage stability of the photocured product may deteriorate or the photopolymerization initiator may precipitate from the liquid photosensitive resin composition.

Next, the photosensitive resin composition suitably applied to the present invention is:
It contains as an essential component a copolymer (component C) consisting of an α,β-ethylenically unsaturated carboxylic acid, a monoolefinically unsaturated compound, and an α,β,β-ethylene saturated carboxylic acid ester.

As the α,β-ethylenically unsaturated saturated carboxylic acid, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid or their monoesters, citraconic acid, mesaconic acid, etc. are used. Ru. Acrylic acid and methacrylic acid are particularly preferred.

The polymerized amount of α, β-ethylenically unsaturated carboxylic acid in the copolymer is 1 to 25% by weight, and if it is less than 1% by weight, the hydrophilic groups in the copolymer are reduced. , the developability with alkaline aqueous solution becomes insufficient, and on the other hand, if it exceeds 25% by weight, the hygroscopicity in the air in the copolymer increases, and the electrical insulation properties of the photocured product decrease, making it difficult to use as a water resist for printed circuit boards. I can't get anything satisfying.

In addition, examples of monoolefinically unsaturated compounds include styrene, α-methylstyrene, 0-methylstyrene,
Styrenic monomers such as m-methylstyrene, p-methylstyrene, 0-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 0-methoxystyrene, m-methoxystyrene, p-methoxystyrene, acrylonitrile, methacrylateril, etc. Vinyl cyanide monomers, halogenated olefin monomers such as vinyl chloride and vinylidene chloride, amide yarns such as acrylamide and methacrylamide, and vinyl ester monomers such as vinyl acetate are used. Styrene from the point of view of resistance and heat resistance,
Styrenic monomers such as α-methylstyrene are preferred.

These monoolefin-based unsaturated compounds are used to provide mechanical properties such as strength and elongation to the photocured product of a liquid photosensitive resin composition using the above-mentioned copolymer. The copolymerization amount of the system unsaturated compound is 5 to 20
If the weight ratio is less than 5% by weight, the photocured product of the photosensitive resin composition will have low strength, while if it exceeds 20% by weight, the photocured product will become brittle, making it difficult to use as a photoresist for producing printed circuit boards. I can't get it.

Further, examples of α, β, β-ethylene saturated carboxylic acid esters include methyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl acrylate, isopropyl acrylate-1, n-butyl acrylate, 5ec-butyl acrylate, tert-butyl Acrylic acid esters or methacrylic acid esters such as acrylate, n-pentyl acrylate, n-hexyl acrylate, n-octyl acrylate, n-decyl acrylate, lauryl acrylate, n-octadecyl acrylate; dimethyl maleate, diethyl maleate, maleic acid Unsaturated dibases such as dioctyl, dimethyl fumarate, diethyl fumarate, diptyl fumarate, dioctyl fumarate, di(2-ethylhexyl) fumarate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, dioctyl itaconate, etc. acid diester,
Hydroxyalkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl methacrylate are used, and among these, it is preferable to use butyl acrylate as one component from the viewpoint of impact resistance of the photocured product. From the viewpoint of hardness, it is preferable to use methyl methacrylate as one component.

The copolymerized amount of α,β-ethylenically unsaturated carboxylic acid ester in the copolymer is 55 to 94% by weight, and if it exceeds 94% by weight, α,β-ethylenically unsaturated carboxylic acid ester in the copolymer is The content of acid units decreases, and the alkali solubility of the liquid photosensitive resin composition becomes insufficient.

Each of the monomers constituting the above-mentioned copolymer is independently
Or a mixture of two or more types is used.

Note that the copolymer of component C is synthesized by radical polymerizing the three components.

For polymerization, alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, heptane, hexane,
Aliphatic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, and polar solvents such as dimethyl sulfoxide and dimethylformamide are used as polymerization solvents.

The solvents used in this polymerization may be used as they are in the preparation of the liquid photosensitive resin composition, or these solvents may be newly blended as one component of the liquid photosensitive resin composition.

As polymerization catalysts, azo initiators such as azobisisobutyronitrile and abiscyclohexanecarbonitrile, and peroxides such as benzoyl peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, and cumene hydroperoxide are used. be done. The polymerization temperature is selected depending on the type of solvent and polymerization catalyst used in the polymerization, but is 50 to 120°C, preferably 60 to 100°C.
It is ℃.

The amount of component C added is 5 to 70% by weight, preferably 5 to 30% by weight; if it is less than 5% by weight, the alkali developability will decrease, while if it exceeds 70% by weight, the relative The amount of component A used decreases, and as a result, the crosslinking density of the photocured product decreases, resulting in a decrease in heat resistance and cold shock resistance.

The photosensitive resin composition suitably applied to the present invention usually contains a sensitizer, a dispersant, a plasticizer, an anti-sagging agent, a leveling agent, and an antifoaming agent, as required in each of the components A to C. Add additives such as additives, flame retardants, brighteners, colorants, etc., and disperse them uniformly using a stirrer such as a super mixer, or dissolve them in an organic solvent, and then scatter the organic solvent under reduced pressure. Prepare. Further, at this time, a certain amount of the organic solvent can be left in the liquid photosensitive polymer composition and dispersed after coating. At this time, the liquid photosensitive resin composition has a viscosity of 10
0-200,0OOcps, preferably 1.000-1
It is preferable to form the resist pattern of the present invention by adjusting the resist pattern three times to 00,000 cps, and by using a liquid photosensitive resin composition having such a viscosity,
Intrusion of the composition into the through-hole portions of the printed circuit board can be suppressed, and undeveloped portions of the through-hole portions can be eliminated.

The resist pattern forming method of the present invention is not limited to forming a solder mask, but can be used for plating, etching, circuit fabrication of printed circuit boards, and the like.

〔Effect of the invention〕

As described above, according to the present invention, (1) it is possible to form a photosensitive resin layer with a constant thickness on a printed circuit board, and (2) when the printed circuit board is pressed against a flexible support, the substrate The pattern mask is tightly attached to the photosensitive resin layer on the printed circuit board via a flexible support that can be used repeatedly, so that bubbles caused by air etc. do not get caught in the upper photosensitive resin layer. Since the photosensitive resin layer is irradiated with actinic rays through the pattern mask, the masking film can be exposed without any stains caused by the photosensitive resin. (2) By using a flexible support that can be used repeatedly. , it is possible to produce solder masks extremely economically in order to prevent contamination of pattern masks. - The uncured photosensitive resin adheres to the peeled flexible support and is recovered and reused. It is economical, and since the uncured photosensitive resin can be removed from the board, the rate of contamination of the developer can be reduced. ■ Solder mask with no undeveloped photosensitive resin in the through-holes of the printed circuit board. can be formed,
It has many advantages such as:

[Brief explanation of drawings]

FIG. 1 is a block diagram of a resist pattern forming apparatus for forming a solder mask on a printed wiring circuit board, which is an embodiment B for explaining the resist pattern forming method of the present invention.

Claims (1)

[Claims] (1) A liquid photosensitive resin or a liquid photosensitive resin composition is applied to a uniform thickness on a substrate, and then the coated surface of the substrate is pressed at a constant pressure with an endless transparent flexible support that is used repeatedly. The flexible support is then irradiated with actinic light through a pattern mask that is in close contact with the flexible support, and then the flexible support is peeled off to remove the uncured liquid photosensitive resin or A method for forming a resist pattern, which comprises collecting a liquid photosensitive resin composition and developing a photosensitive resin layer or a photosensitive resin composition layer on a substrate.