JP2012042633A - Method for manufacturing resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a resist pattern including: at least (a) a step of forming a photocrosslinking resin layer on a substrate; (b) a step of thinning the photocrosslinking resin layer; (d) a step of exposing a circuit pattern; and (e) a developing step, which includes a conveying step and the exposing step, in which scratch or foreign matter adhesion on the surface of the photocrosslinking resin layer is prevented, causes no contamination on a phototool even when contact exposure is performed, and causes no thickening of lines caused by refraction of light and no polymerization inhibition due to oxygen in the periphery of a step even when the photocrosslinking resin layer has a step.SOLUTION: The method for manufacturing the resist pattern includes (f) a step of sticking a masking film in which a transparent film and a non-photosensitive alkali-soluble adhesive layer are laminated onto a photocrosslinking resin layer after (b) a step of thinning the photocrosslinking resin layer, and includes (g) a step of removing the transparent film after (c) a step of exposing a circuit pattern.

Description

  The present invention relates to a method for producing a resist pattern such as an etching resist for forming a fine circuit or a solder resist.

  As a method of manufacturing printed wiring boards and lead frames, an etching resist layer is provided on an insulating substrate having a conductive layer on the surface or a circuit portion of the conductive substrate, and the exposed conductive layer of the non-circuit portion is removed by etching. There is a subtractive method for forming a conductive pattern. In addition, there are an additive method and a semi-additive method in which a conductive layer is provided on a circuit portion of an insulating substrate by a plating method.

  As electronic devices have become smaller and more multifunctional in recent years, printed wiring boards and lead frames used inside the devices have been increased in density and conductive patterns. Has a conductive pattern of 50 to less than 80 μm and a conductor gap of 50 to 80 μm. In addition, with higher density and finer wiring, ultrafine conductive patterns with a conductor width or conductor gap of less than 50 μm have been required. Along with this, the requirements for the accuracy and impedance of the conductive pattern are also increasing. In order to form such a fine conductive pattern, a semi-additive method has been studied instead of the subtractive method. However, there are problems such as a significant increase in the manufacturing process and insufficient adhesive strength of electrolytically plated copper. There was a problem. For this reason, the production of printed wiring boards and lead frames by the subtractive method has become the mainstream.

  In the subtractive method, the etching resist layer is formed by a photofabrication method, a screen printing method, an ink jet method or the like having an exposure and development process using a photosensitive material. Among these, the method using a sheet-like photocrosslinkable resin layer called a negative dry film resist in the photofabrication method is preferably used because it is easy to handle and can protect through holes by tenting. It has been.

  In the method using a photocrosslinkable resin layer, a photocrosslinkable resin layer is formed on a substrate, and an etching resist layer is formed through exposure and development steps. In order to form a fine conductive pattern, it is indispensable to form a fine etching resist layer. For this reason, it is necessary to make the resist film thickness as thin as possible. For dry film resists that are common as photocrosslinkable resin layers, for example, if the film thickness is 10 μm or less, the resist layer may be peeled off or disconnected due to the inclusion of bubbles with dust as a core and the decrease in follow-up of unevenness. It is difficult to form a fine etching resist layer.

  In order to solve such a problem, after forming a thick photocrosslinkable resin layer on the substrate in advance, and then thinning the photocrosslinkable resin layer using an aqueous alkali solution containing a high concentration of inorganic alkaline compound, A method of forming an etching resist layer by exposing and developing a circuit pattern has been proposed (see, for example, Patent Document 1).

  According to this method, it was possible to form a fine etching resist layer with a thin film. However, in the case of conventional dry film resists, since a polyester film is mainly laminated as a support film in a state that protects the photocrosslinkable resin layer until before the development step, adhesion of scratches and foreign matters in the transport step and exposure step However, in the above method, after the photocrosslinkable resin layer is thinned, the surface of the film is exposed. There was a problem of contamination of the photo tool.

  In order to solve this problem, Patent Document 1 proposes a method for producing a conductive pattern including a step of thinning a photocrosslinkable resin layer and then re-laminating a transparent film on the photocrosslinkable resin layer. ing. However, the adhesiveness between the transparent film and the photocrosslinkable resin layer is poor only by pasting the transparent film by thermocompression bonding. For example, the transparent film is peeled off when passed through a cleaning roller before exposure. There was a problem that.

  Patent Document 1 also proposes a method of performing a thinning process in order to form a fine etching resist layer in a method for manufacturing a circuit board having holes. Specifically, (a) a step of forming a photocrosslinkable resin layer on a substrate having a hole, (i) curing the photocrosslinkable resin layer on the hole and its peripheral part (hereinafter also referred to as “land part”). (B ') a step of thinning the photocrosslinkable resin layer of the uncured portion with an alkaline aqueous solution, (c) a circuit pattern exposure step, (d) a development step, and (e) an etching step in this order. A method for producing a conductive pattern including the above has been proposed. According to this method, after the thick photocrosslinkable resin layer is pasted, the photocrosslinkable resin layer on the hole and its surroundings is pre-cured, so that the land portion can be tented with a thick etching resist layer. The tent is not easily broken in the development and etching processes. Further, in a portion other than the land portion, a fine circuit can be formed by exposing, developing, and etching the circuit pattern after the thinning process.

  However, similarly to the above, since the surface of the photocrosslinkable resin layer after thinning is exposed, there are problems of adhesion of scratches and foreign matter, and contamination of the phototool. In addition, since there is a thickness difference (step) on the hole and between its peripheral part and the thinned part, if the contact exposure is performed using a photo tool in the exposure process of the circuit pattern, the light is refracted around the step. In some cases, poor resolution due to line thickening may occur. Further, even when vacuum suction is performed during contact exposure, air cannot be completely removed around the step, and radical polymerization is inhibited by oxygen, resulting in film loss and resolution degradation.

  Even if a transparent film is re-laminated on the photocrosslinkable resin layer after thinning the photocrosslinkable resin layer, the normal transparent film can completely follow the steps of the photocrosslinkable resin layer. As described above, it is extremely difficult to cause problems such as poor resolution due to line thickening, film loss due to polymerization inhibition, and deterioration of resolution, similar to the above.

International Publication No. 2009/096438 Pamphlet

  The problems of the present invention are at least (a) a step of forming a photocrosslinkable resin layer on a substrate, (b) a step of thinning the photocrosslinkable resin layer, (c) an exposure step of a circuit pattern, (d ) In a resist pattern preparation method including a development step, there is no method of creating a resist pattern that does not contaminate the phototool even if contact exposure is performed without any scratches or foreign matter adhering to the surface of the photocrosslinkable resin layer in the transport step or exposure step. Is to provide. It is another object of the present invention to provide a method for producing a resist pattern that does not cause line thickening due to light refraction or inhibition of polymerization by oxygen even when there is a step in the photocrosslinkable resin layer.

(1) (a) a step of forming a photocrosslinkable resin layer on the substrate, (b) a step of thinning the photocrosslinkable resin layer, (f) a transparent film and a non-photosensitive alkali-soluble adhesive layer A step of adhering the non-photosensitive alkali-soluble adhesive layer on the photocrosslinkable resin layer, (c) an exposure step of the circuit pattern, (g) a step of removing the transparent film, (D) a resist pattern production method including a development step;
(2) (a) a step of forming a photocrosslinkable resin layer on the substrate, (i) a step of exposing a part of the photocrosslinkable resin layer, (b ′) a photocrosslinkable resin layer other than the exposed region (F ') a masking film in which a transparent film and a non-photosensitive alkali-soluble adhesive layer are laminated so that the non-photosensitive alkali-soluble adhesive layer is in contact with the photocrosslinkable resin layer. A step of attaching, (c) a circuit pattern exposure step, (g) a step of removing the transparent film, and (d) a development step,
I found.

  In the method for producing a resist pattern of the present invention, after a thinning treatment of a photocrosslinkable resin layer, a masking film in which a transparent film and a non-photosensitive alkali-soluble adhesive layer are laminated is used as a non-photosensitive alkali-soluble adhesive. The layer is stuck so as to contact the photocrosslinkable resin layer. By laminating the non-photosensitive alkali-soluble adhesive layer on the transparent film, the adhesion between the photocrosslinkable resin layer after thinning and the transparent film, which has been a problem in the past, is significantly improved. Further, even when there is a step in the photocrosslinkable resin layer, the alkali-soluble adhesive layer of the masking film is buried so as to follow the step, so that air is excluded, so that radical polymerization inhibition by oxygen does not occur. In addition, since the non-photosensitive alkali-soluble adhesive layer follows the step, the transparent film is flatly attached to the substrate without wrinkles. There is no resolution failure due to fatness. Furthermore, since the non-photosensitive alkali-soluble adhesive layer of the masking film is soluble in alkali, it is completely dissolved and removed together with the uncured portion of the photocrosslinkable resin layer in the subsequent development process. This alkali-soluble adhesive layer does not remain. Of course, by applying a masking film on the photocrosslinkable resin layer after thinning treatment, it is possible to prevent scratches and adhesion of foreign substances in the transport process and exposure process, and to the photo tool during contact exposure. There is no pollution problem.

It is a cross-sectional process drawing which shows an example of the production method of the resist pattern including the process of thinning a photocrosslinkable resin layer. It is sectional process drawing which shows an example of the production method (1) of the resist pattern of this invention. It is sectional process drawing which shows an example of the production method (2) of the resist pattern of this invention. It is sectional process drawing which shows an example of the production method (2) of the resist pattern of this invention. It is sectional process drawing which shows an example of the production method (2) of the resist pattern of this invention.

  Hereinafter, a method for producing a resist pattern of the present invention will be described in detail.

  FIG. 1 is a cross-sectional process diagram illustrating an example of a resist pattern manufacturing method including a process of thinning a photocrosslinkable resin layer. In FIG. 1, a substrate 2 in which a conductive layer 4 is provided on one surface of an insulating substrate 5 is used. In the step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 4 of the substrate 2. In the step (b), the photocrosslinkable resin layer is thinned. In the step (c), the photocrosslinkable resin layer corresponding to the circuit pattern is exposed to form the cured portion 3. In the step (d), the photocrosslinkable resin layer (uncured portion) 1 is removed by development to obtain a resist pattern.

  FIG. 2 is a cross-sectional process diagram illustrating an example of a resist pattern manufacturing method (1) according to the present invention. In FIG. 2, in step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 4 of the substrate 2 in which the conductive layer 4 is provided on one surface of the insulating substrate 5. In the step (b), the photocrosslinkable resin layer 1 is thinned. In the step (f), a masking film 8 in which a transparent film 6 and a non-photosensitive alkali-soluble adhesive layer (hereinafter sometimes abbreviated as “adhesive layer”) 7 are laminated is pasted on the photocrosslinkable resin layer. . Since the pressure-sensitive adhesive layer 7 is in close contact with the photocrosslinkable resin layer after being thinned, the transparent film 6 is not peeled even when passed through a clean roller or the like. In the step (c), the portion of the photocrosslinkable resin layer corresponding to the circuit pattern is exposed to form the cured portion 3 while the masking film 8 is still laminated. In the step (g), the transparent film 6 is removed. In the step (d), the remaining photocrosslinkable resin layer (uncured portion) 1 and the adhesive layer 7 are removed by development to obtain a resist pattern.

  FIG. 3 is a cross-sectional process diagram illustrating an example of a resist pattern manufacturing method (2) according to the present invention. In FIG. 2, in step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 4 of the substrate 2 in which the conductive layer 4 is provided on one surface of the insulating substrate 5. In the step (i), a part of the photocrosslinkable resin layer 1 is exposed and cured to form a cured portion 9. In the step (b ′), the photocrosslinkable resin layer (uncured portion) 1 is thinned. In the step (f ′), a masking film 8 in which the transparent film 6 and the adhesive layer 7 are laminated is pasted on the photocrosslinkable resin layer. Since the adhesive layer 7 is in close contact with the photocrosslinkable resin layer 1 and the cured portion 9 after being thinned, the transparent film 6 is not peeled even when passed through a clean roller or the like. Further, the transparent film 6 is flatly attached to the substrate without wrinkles, and the adhesive layer 7 follows the step between the cured portion 9 and the photocrosslinkable resin layer after thinning, so that the periphery of the step Insufficient resolution due to light leakage and polymerization inhibition due to oxygen do not occur. In the step (c), the portion of the photocrosslinkable resin layer corresponding to the circuit pattern is exposed to form the cured portion 3 while the masking film 8 is still laminated. In the step (g), the transparent film 6 is removed. In the step (d), the remaining photocrosslinkable resin layer (uncured portion) 1 and the alkali-soluble adhesive layer 7 are removed by development to obtain a resist pattern.

  4 to 5 are cross-sectional process diagrams showing an example of a resist pattern manufacturing method (2) according to the present invention. The substrate 2 has a hole 10, and a conductive layer 4 is provided on the surface and inside the hole. In FIG. 4, in step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 4 on the surface of the substrate 2 so as to close the hole 10. In step (i), the photocrosslinkable resin layer 1 on and around the hole 10 is exposed and cured to form a cured portion 9. In the step (b ′), the photocrosslinkable resin layer (uncured portion) 1 is thinned. In the step (f ′), a masking film 8 in which the transparent film 6 and the adhesive layer 7 are laminated is pasted on the photocrosslinkable resin layer. In the step (c), the portion of the photocrosslinkable resin layer corresponding to the circuit pattern is exposed to form the cured portion 3 while the masking film 8 is still laminated. In the step (g), the transparent film 6 is removed. In the step (d), the remaining photocrosslinkable resin layer (uncured portion) 1 and the adhesive layer 7 are removed by development to obtain a resist pattern.

  For the formation of the photocrosslinkable resin layer, for example, a thermocompression laminator device that presses and presses a heated rubber roll can be used. The heating temperature is preferably 100 ° C. or higher. The substrate before lamination may be subjected to pretreatment such as alkali degreasing and pickling.

  In the present invention, a substrate having a conductive layer on the surface is preferably used. Examples of such a substrate include a printed wiring board or a lead frame substrate. Examples of the printed wiring board include a flexible substrate and a rigid substrate. The thickness of the insulating substrate of the flexible substrate is 5 to 125 μm, and a metal foil layer of 1 to 35 μm is provided as a conductive layer on both sides or one side, and the flexibility is high. As the material for the insulating substrate, polyimide, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polymer, or the like is usually used. The material having the metal foil layer on the insulating substrate is an insulating substrate by an adhesive method of bonding with an adhesive, a casting method of applying a resin liquid which is an insulating substrate material on the metal foil, a sputtering method or a vapor deposition method. Produced by any method, such as sputtering / plating, which forms a metal foil layer by electrolytic plating on a thin conductive layer (seed layer) with a thickness of several nanometers formed on a resin film, or laminating by hot pressing. May be used. As a metal of the metal foil layer, any metal such as copper, aluminum, silver, nickel, chromium, or an alloy thereof can be used, but copper is generally used.

  As a rigid substrate, a paper substrate or glass substrate soaked with an epoxy resin or a phenol resin is overlapped to form an insulating substrate, and a metal foil is placed on one or both sides as a conductive layer, and heated and pressed. A laminated layer provided with a metal foil layer can be used. Moreover, the multilayer board which has a through-hole and a non-through-hole, and the multilayer shield board produced by laminating | stacking a prepreg, metal foil, etc. after an inner layer wiring pattern process is also mentioned. The thickness is 60 μm to 3.2 mm, and the material and thickness thereof are selected according to the final use form as a printed circuit board. Examples of the material for the metal foil layer include copper, aluminum, silver, and gold. Copper is the most common.

  For a substrate having a hole and a conductive layer provided on the surface and inside the hole, for example, a hole is formed by drilling or lasering on a substrate having a metal foil layer on the surface of the insulating substrate. It is produced by performing a plating process such as electrolytic plating or electrolytic plating to form a plated metal layer on the surface including the inside of the hole.

  Examples of these printed circuit boards are “Printed Circuit Technology Handbook” (edited by Japan Printed Circuit Industry Association, published in 1987, published by Nikkan Kogyo Shimbun Co., Ltd.) and “Multilayer Printed Circuit Handbook” (JA Scarlet). Ed., Published in 1992, published by Modern Chemical Co., Ltd.). Examples of the lead frame substrate include iron nickel alloy and copper alloy substrates.

  The photocrosslinkable resin layer is a resin layer in which an exposed portion is cured and insolubilized in a developer, and a negative dry film resist is generally used for forming a circuit. A commercially available dry film resist has at least a photocrosslinkable resin layer, and is provided with a photocrosslinkable resin layer on a support layer film such as polyester. In some cases, a protective film such as polyethylene covers the photocrosslinkable resin layer. Many have a three-layer structure. In the present invention, commercially available dry film resists that can be used as the photocrosslinkable resin layer include, for example, Sunfort (registered trademark) series (manufactured by Asahi Kasei E-materials), Photec (registered trademark) series (manufactured by Hitachi Chemical Co., Ltd.). ), Liston (registered trademark) series (manufactured by DuPont MRC Dry Film), ALPHA (registered trademark) series (manufactured by Nichigo Morton), and the like.

  The photocrosslinkable resin layer comprises (A) a polymer containing a carboxyl group, (B) a photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule, and (C) a photopolymerization initiator. It may contain and may contain a solvent and other additives further. Their blending ratio is determined by a balance of required properties such as sensitivity, resolution, degree of cure, and tenting properties. Examples of the composition of the photo-crosslinkable resin layer are “Photopolymer Handbook” (edited by Photopolymer Social Society, published in 1989, published by Kogyo Kenkyukai) and “Photopolymer Technology” (edited by Akio Yamamoto and Mototaro Nagamatsu, 1988, published by Nikkan Kogyo Shimbun Co., Ltd., etc., and a desired photocrosslinkable resin composition can be used.

  The thickness of the photocrosslinkable resin layer is preferably 15 to 100 μm, and more preferably 20 to 50 μm. If the thickness is less than 15 μm, resist peeling or disconnection may occur due to the mixing of bubbles with dust as a core and the uneven followability. On the other hand, when the thickness exceeds 100 μm, not only the production cost of the photocrosslinkable resin layer is increased, but also the edge fusion of the produced photocrosslinkable resin layer is remarkable and the storage stability may be deteriorated.

  In steps (b) and (b ′), the photocrosslinkable resin layer is thinned. An alkaline aqueous solution can be suitably used for the thinning treatment. Examples of alkaline aqueous solutions include alkali metal carbonates such as lithium or sodium or potassium carbonate or bicarbonate, alkali metal phosphates such as potassium or sodium phosphate, lithium, sodium or potassium hydroxide, etc. Among inorganic alkali compounds selected from alkali metal silicates such as alkali metal hydroxides, potassium and sodium silicates, organic alkaline compounds such as ethanolamines, ethylenediamine, propanediamine, triethylenetetramine, morpholine, etc. At least one of them is included. Among these, particularly preferable compounds include sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and the like. As for content of an alkaline compound, 5-20 mass parts is preferable, More preferably, it is 10-15 mass parts. If the amount is less than 5 parts by mass, unevenness tends to be easily caused by the thinning treatment. If the amount exceeds 20 parts by mass, precipitation or separation of the alkaline compound is likely to occur, resulting in poor stability over time and workability of the liquid. There is. The pH of the solution is preferably in the range of 9-12. Moreover, surfactant, an antifoamer, a solvent, etc. can be suitably added to alkaline aqueous solution.

  After performing the thinning treatment with an alkaline aqueous solution, it is necessary to sufficiently wash the substrate with water. There are a dip method, a paddle method, a spray method, and the like as a washing method, and the spray method is most suitable from the viewpoint of uniformity. Moreover, after washing the photocrosslinkable resin layer surface with water, water droplets can be removed. Examples of the washing water include industrial water, tap water, ion exchange water, and distilled water. Examples of the method for removing water droplets on the surface of the resin layer include an air knife, a liquid-absorbing roll, and hot air drying. An air knife is particularly preferable because there is no physical contact and good removal efficiency.

  When the support layer film is provided on the photocrosslinkable resin layer, the thinning treatment is performed after the film is peeled off. The thinning treatment is a treatment for reducing the thickness of the photocrosslinkable resin layer substantially uniformly. Specifically, the thickness is reduced to 0.05 to 0.9 times the thickness before the thinning treatment. That means.

  There are dipping method, paddle method, spray method, brushing, scraping and the like as the thinning treatment method, and the spray method is most suitable from the viewpoint of the dissolution rate of the photocrosslinkable resin layer. In the case of the spray method, the treatment conditions (temperature, time, spray pressure) are appropriately adjusted according to the dissolution rate of the photocrosslinkable resin layer to be used. Specifically, the treatment temperature is preferably 10 to 50 ° C, more preferably 15 to 40 ° C, and further preferably 15 to 35 ° C. The spray pressure is preferably 0.01 to 0.5 MPa, and more preferably 0.02 to 0.3 MPa.

  In the steps (f) and (f ′), a masking film in which a transparent film and an adhesive layer are laminated is attached on the photocrosslinkable resin layer. Although it depends on low molecular weight components such as monomers and oligomers contained in the photocrosslinkable resin layer, the tackiness of the photocrosslinkable resin layer after the thinning treatment is often reduced as compared with that before the treatment. In the present invention, even if the photocrosslinkable resin layer after the thinning treatment has low tackiness, the adhesive layer is in close contact with the surface of the photocrosslinkable resin layer, and therefore the transparent film is not easily peeled off. In addition, the presence of the transparent film greatly reduces defects due to scratches and foreign matters in the transport process and exposure process.

  The masking film is composed of a transparent film and an adhesive layer. The transparent film is peeled off from the adhesive layer immediately before development. As the transparent film, any film can be used as long as it has a high transmittance for short-wavelength visible light or near-ultraviolet rays. For example, although a polyester film, a polyethylene film, a polyvinyl chloride film, a polypropylene film, a polycarbonate film, etc. are mentioned, a polyester film is preferable. Polyester is a polycondensation product of an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and a monomer containing diol as main constituent components.

  Polyester constituting the polyester film includes, as dicarboxylic acid components, aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid, and aliphatic carboxylic acids such as adipic acid, azelaic acid, sebacic acid, and decanedicarboxylic acid. An alicyclic dicarboxylic acid such as acid or cyclohexanedicarboxylic acid can be used, and the diol component includes an aliphatic diol such as ethylene glycol, diethylene glycol, butanediol, pentanediol, and hexanediol, and an alicyclic such as cyclohexanedimethanol. Diols can be used.

  As the transparent film, among polyester films, it is particularly preferable to use a film mainly composed of polyethylene terephthalate produced by dehydration polymerization of terephthalic acid and ethylene glycol. The polyethylene terephthalate film has solvent resistance and mechanical strength, and is excellent in laminate suitability and peelability. Further, it is easy to use as an optical film because it has excellent transmittance and refractive index and is economically advantageous.

  Further, the haze value H of the transparent film is preferably 10% or less, more preferably 5% or less, and further preferably 1.5% or less. The haze value H is a value representing turbidity. From the total transmittance T of the light irradiated by the light source and transmitted through the sample and the transmittance D of the light diffused and scattered in the sample, H (%) = ( D / T) × 100. This is defined by JIS-K-7105 and can be easily measured by a commercially available haze meter (for example, trade name: NDH-500, manufactured by Nippon Denshoku Industries Co., Ltd.). When the haze value exceeds 10%, the transparency is lowered, and photocuring may be inhibited. As a transparent film having a haze value of 10% or less, for example, Teijin (registered trademark) Tetoron (registered trademark) film (manufactured by Teijin DuPont Films), Mylar (registered trademark) (manufactured by Teijin DuPont Films), Merinex ( Registered trademark) (manufactured by Teijin DuPont Films), Diafoil (registered trademark) (manufactured by Mitsubishi Plastics), Lumirror (registered trademark) (manufactured by Toray Film Processing Co., Ltd.), and the like.

  The thickness of the transparent film is preferably 10 to 25 μm, and more preferably 12 to 25 μm. If it exceeds 25 μm, the resolution may be lowered, and it may be economically disadvantageous. On the other hand, when the thickness is less than 10 μm, the mechanical strength is insufficient, and tearing may easily occur during peeling.

  The adhesive layer is not sensitive to short-wavelength visible light or near-ultraviolet rays, is soluble in an alkaline aqueous solution, and is attached as an intermediate layer between the transparent film and the photocrosslinkable resin layer after thinning. Any one is acceptable. Moreover, it is necessary to peel from the transparent film immediately before development. After the transparent film is peeled off, the adhesive layer remains on the photocrosslinkable resin layer, so that it needs to be completely dissolved in the subsequent step (d).

  The adhesive layer only needs to contain a polymer soluble in an alkaline aqueous solution. For example, acrylic resin, methacrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin, alkyd resin Examples thereof include organic polymers such as resins and phenolic resins. Among these, it is preferable that it is a thing obtained by superposing | polymerizing (radical polymerization etc.) the monomer (polymerizable monomer) which has an ethylenically unsaturated double bond. In view of developability with an aqueous alkali solution, an acrylic resin or a methacrylic resin is preferable. These polymers soluble in an alkaline aqueous solution may be used alone or in combination of two or more. Examples of such a monomer having an ethylenically unsaturated double bond include styrene; vinyl toluene, α-methyl styrene, p-methyl styrene, p-ethyl styrene, p-methoxy styrene, p-ethoxy styrene. Styrene derivatives such as p-chlorostyrene and p-bromostyrene; acrylamide such as diacetone acrylamide; acrylonitrile; esters of vinyl alcohol such as vinyl-n-butyl ether; (meth) acrylic acid alkyl ester; (meth) acrylic acid Tetrahydrofurfuryl ester, (meth) acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, (meth) acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth) acrylate, 2,2, 3,3-te Rafluoropropyl (meth) acrylate, (meth) acrylic acid, α-bromo (meth) acrylic acid, α-chloro (meth) acrylic acid, β-furyl (meth) acrylic acid, β-styryl (meth) acrylic acid, etc. (Meth) acrylic acid monoesters; maleic monomers such as maleic acid, maleic anhydride, monomethyl maleate, monoethyl maleate, monoisopropyl maleate; fumaric acid, cinnamic acid, α-cyanocinnamic acid , Itaconic acid, crotonic acid, propiolic acid and the like.

Examples of the (meth) acrylic acid alkyl ester include the following general formula (I):
^{_{CH 2 = C (R 1)}} -COOR 2 (I)
[In Formula (I), R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 12 carbon atoms. ]
And compounds in which a hydroxyl group, an epoxy group, a halogen atom, or the like is substituted on the alkyl group of these compounds.

  The adhesive layer preferably contains a carboxyl group in consideration of developability with an alkaline aqueous solution. Therefore, the polymerizable monomer having a carboxyl group and other polymerizable monomer are radically polymerized. Examples of the polymerizable monomer having a carboxyl group include (meth) acrylic acid, vinylbenzoic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, cinnamic acid, and acrylic acid dimer. be able to. Of these, (meth) acrylic acid is most preferred. Further, the content of (meth) acrylic acid is preferably 20% by mass or more in terms of the monomer composition ratio in the polymer soluble in the alkaline aqueous solution.

  Polymers soluble in an aqueous alkali solution that can be used for the adhesive layer can be used alone or in combination of two or more. As a combination of polymers soluble in an alkaline aqueous solution when two or more types are used in combination, for example, a combination of polymers soluble in two or more alkaline aqueous solutions having different copolymerization components, different mass average molecular weights. Examples thereof include a combination of polymers soluble in two or more types of alkaline aqueous solutions and a combination of polymers soluble in two or more types of alkaline aqueous solutions having different dispersities (mass average molecular weight / number average molecular weight).

  The mass average molecular weight of a polymer soluble in an alkaline aqueous solution that can be used for the adhesive layer is preferably 10,000 to 200,000, and more preferably 10,000 to 150,000. If the weight average molecular weight is less than 10,000, the flexibility is inferior and it may be difficult to form a coating of the adhesive layer. On the other hand, if it exceeds 200,000, the developability with respect to an aqueous alkali solution tends to deteriorate. There is.

  The acid value of the polymer soluble in an alkaline aqueous solution that can be used for the adhesive layer is preferably 50 to 300 mgKOH / g, and more preferably 100 to 250 mgKOH / g. When the acid value is less than 50 mgKOH / g, the development time tends to be long. On the other hand, when the acid value exceeds 300 mgKOH / g, sticking to the surface of the photocrosslinkable resin after thinning may be deteriorated.

  If necessary, a plasticizer such as dibutyl phthalate, polyethylene glycol, or p-toluenesulfonamide is added to the adhesive layer as a component other than the polymer soluble in the alkaline aqueous solution as necessary. can do. By adding these plasticizers, flexibility is obtained even below the glass transition temperature of the above polymer soluble in an alkaline aqueous solution, and the use of plasticizers is also useful in terms of tackiness and flexibility. Such components can be used alone or in combination of two or more.

  If necessary, the adhesive layer is made of alcohols such as methanol, ethanol, n-propanol, 2-butanol and n-hexanol; ketones such as acetone and 2-butanone; ethyl acetate, butyl acetate and acetic acid-n-amyl. , Esters such as methyl sulfate, ethyl propionate, dimethyl phthalate and ethyl benzoate, aromatic hydrocarbons such as toluene, xylene, benzene and ethylbenzene; tetrahydrofuran, diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether It can be dissolved in an ether such as 1-methoxy-2-propanol, a solvent such as N, N-dimethylformamide, dimethyl sulfoxide, or a mixed solvent thereof to obtain a uniform solution.

  The thickness of the pressure-sensitive adhesive layer is preferably 0.5 to 10 μm, more preferably 1 to 5 μm, after drying. However, in the present invention, when there is a step in the photocrosslinkable resin layer, in order for the adhesive layer to follow the step, a film thickness larger than the formed step is required.

  In the step (f), as a method for attaching the masking film on the photocrosslinkable resin layer after thinning, air or foreign matter is bitten without causing a gap between the photocrosslinkable resin layer and the masking film. Any method may be used as long as the masking film can be laminated on the photocrosslinkable resin layer almost uniformly without undulation. For example, a pressure-bonding laminator device that presses and presses a rubber roll can be used. At this time, the rubber roll is preferably heated to a temperature equal to or higher than the glass transition temperature of the adhesive layer, and it is necessary to adjust the pressure, the conveyance speed, etc. so that the photocrosslinkable resin layer does not flow out between the substrate and the masking film. There is.

  In the step (f '), when a masking film is pasted on the photocrosslinkable resin layer having a step after thinning, if a hot roll laminator made of a horizontal transport rubber roll is used under atmospheric pressure, Microbubbles are conspicuously mixed. In particular, it is easy to mix in the rear in the transport direction. Therefore, in order to eliminate such fine bubbles mixed around the step, it is preferable to laminate in a reduced pressure atmosphere. Moreover, when using a vacuum laminator, it is preferable to heat the masking film and attach it in a state where flexibility is imparted.

  The decompression condition of the vacuum lamination is preferably 10 to 30000 Pa, more preferably 10 to 10000 Pa, and still more preferably 10 to 1000 Pa. If the degree of vacuum is less than 10 Pa, the decompression time becomes too long, which is not preferable. On the other hand, when the degree of vacuum exceeds 30000 Pa, the effect of pressure reduction is small, and minute bubbles around the step may not be completely removed. The hardness of the laminate roll is preferably 60 to 100 degrees, and more preferably 70 to 100 degrees. If the roll hardness is less than 60 degrees, the effect of suppressing the mixing of minute bubbles is small, and if it exceeds 100 degrees, the production of the roll itself is difficult. The heating temperature of the hot roll is preferably heated to be equal to or higher than the glass transition temperature of the adhesive layer. The roll hardness is a value measured using a durometer GS-719G (manufactured by Teclock Corporation) based on the JIS standard (K-6253A).

  As the laminator apparatus, either a single-stage laminator having a pair of rubber hot rolls or a multi-stage laminator having two or more pairs of hot rolls can be used. In the case of a multistage laminator, a pair of a rubber hot roll and a metal hot roll may be used in combination.

  In step (c), the circuit pattern is exposed. Circuit pattern exposure methods include xenon lamps, high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, reflected image exposure using UV fluorescent lamps as light sources, single-sided or double-sided contact exposure systems using photo tools, proximity systems, and projection systems. In particular, single-sided and double-sided exposure using a photo tool is preferably used with a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, or a UV fluorescent lamp as a light source.

  In the step (g), the transparent film is removed from the masking film, and in the step (d), the photocrosslinkable resin layer (uncured portion) and the adhesive layer are removed with a developer to form a resist pattern. As a development method, using a developer corresponding to the photocrosslinkable resin layer and the adhesive layer to be used, spray is sprayed from the vertical direction of the substrate toward the substrate surface, and unnecessary portions are removed as an etching resist pattern, A resist pattern corresponding to the circuit pattern is formed. In general, an aqueous sodium carbonate solution of 0.3 to 2% by mass is used.

  In step (i), a part of the photocrosslinkable resin layer is cured by exposure to form a stepped region. For example, in the case of a substrate having a hole and a conductive layer provided on the surface and inside of the hole, the land part has a tenting strength by curing the photocrosslinkable resin layer on the hole and its peripheral part. An etching resist layer can be formed. Exposure methods include xenon lamps, high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, reflection image exposure using UV fluorescent lamps as light sources, single-sided or double-sided contact exposure systems using photo tools, proximity systems, projection systems, and laser scanning. Examples include an exposure method.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example.

<Preparation of non-photosensitive alkali-soluble adhesive layer solution>
The components shown in Tables 1 to 4 were mixed to prepare non-photosensitive alkali-soluble adhesive layer solutions A to D.

(Examples 1-4)
<Production of masking film>
After applying and drying the non-photosensitive alkali-soluble adhesive layer solutions A to D on a transparent support layer film (film thickness 16 μm) made of a polyester film using a slit die coater, from a polyethylene film Masking films A to D having a non-photosensitive alkali-soluble adhesive layer having a thickness of 10 μm were prepared by laminating protective films (thickness 30 μm).

<Process (a)>
A heat-resistant silicone rubber lining was surface-treated on a glass-based epoxy resin copper-clad laminate (area 250 mm × 340 mm, copper foil thickness 12 μm, substrate thickness 0.4 mm, trade name: FR-4, manufactured by Mitsubishi Gas Chemical Company). Using a laminator for dry film equipped with a laminating roll, a dry film resist (trade name: Sunfort (trade name: Sunfort) with a roll temperature of 100 ° C., an air pressure of 0.30 MPa, and a laminating speed of 0.50 m / min while peeling off the protective film (Registered trademark) AQ5038, thickness 50 μm, manufactured by Asahi Kasei E-Materials Co., Ltd.).

<Step (b)>
After peeling off the support layer film, the dry film resist was thinned using a horizontal conveyance type continuous processing apparatus. Under the conditions of a liquid temperature of 25 ° C. and a spray pressure of 0.05 MPa, the film is thinned with a 10% sodium carbonate solution so as to have an average film thickness of 25 μm. A photocrosslinkable resin layer was obtained.

<Step (f)>
Using the same laminator as in step (a), masking films A to D were laminated at a roll temperature of 100 ° C., an air pressure of 0.30 MPa, and a laminating speed of 1.50 m / min while peeling off the protective film. In any case, no fine bubbles are mixed between the photocrosslinkable resin layer and the masking film after thinning, and the masking film can be laminated on the photocrosslinkable resin layer flatly without undulations. did it. In addition, a cleaning process was performed from above the masking film using a slightly sticky clean roller (registered trademark) (trade name: RY-501Z, manufactured by Rayon Kogyo Co., Ltd.) before the exposure. I couldn't see it.

<Step (c)>
Using a photo tool in which a pattern of line / space = 25/25 μm is drawn, contact exposure is performed with a vacuum contact exposure apparatus equipped with a 3 kw ultrahigh pressure mercury lamp (trade name: URM-300, manufactured by Ushio Lighting Co., Ltd.) as a light source. went.

<Steps (g) and (d)>
After peeling off only the transparent film of the masking film, development processing is performed using a 1% by mass sodium carbonate aqueous solution (liquid temperature 30 ° C., spray pressure 0.15 MPa), and a photocrosslinkable resin layer (uncured portion). And the adhesive layer were removed to form a resist pattern. As a result of observing the obtained resist pattern with an optical microscope, defects such as line thinning, disconnection, line thickening, and short-circuiting were not found in the pattern of line / space = 25/25 μm.

(Examples 5 to 8)
<Production of masking film>
After applying and drying the non-photosensitive alkali-soluble adhesive layer solutions A to D on a transparent support layer film (film thickness 16 μm) made of a polyester film using a slit die coater, from a polyethylene film The masking films AA to AD having a non-photosensitive alkali-soluble adhesive layer having a film thickness of 30 μm were prepared by laminating a protective film (film thickness 30 μm).

<Process (a)>
Glass substrate epoxy resin copper clad laminate (area 250 mm x 340 mm, copper foil thickness 12 μm, substrate thickness 0.4 mm, trade name: FR-4, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 0.5 mm in diameter using a drill Then, 100 through-holes of 2.0 mm each were formed, and then a copper-clad laminate with holes in which a plated copper layer having a thickness of 25 μm was formed on the inside of the through-holes and on the copper foil was produced. Next, on this copper clad laminate, using a laminator for dry film provided with a heat-resistant silicone rubber-lined laminate roll, while peeling off the protective film, the roll temperature is 100 ° C., the air pressure is 0.30 MPa, the laminate A dry film resist (trade name: Sunfort (registered trademark) AQ5038, thickness 50 μm, manufactured by Asahi Kasei E-Materials) was laminated at a speed of 0.50 m / min.

<Process (i)>
Before thinning the photocrosslinkable resin layer, an ultrahigh pressure mercury lamp with an output of 3 kw (trade name: URM-300, Contact exposure was performed with a vacuum contact exposure apparatus equipped with a light source of USHIO LIGHTING Co., Ltd.

<Process (b ')>
After curing the photocrosslinkable resin layer in the land portion, the support layer film was peeled off, and a dry film resist was thinned using a horizontal transfer type continuous processing apparatus. A thin film using a 10% sodium carbonate solution so that the average film thickness of the photocrosslinkable resin layer (uncured portion) other than the land portion is 25 μm under the conditions of a liquid temperature of 25 ° C. and a spray pressure of 0.05 MPa. The photocrosslinkable resin layer was formed into a thin film by sufficient water washing treatment and cold air drying.

<Process (f ')>
Using a press-type vacuum laminator (trade name: MV-302, manufactured by MC Corporation), a roll temperature of 100 ° C., an air pressure of 0.30 MPa, a laminating speed of 1.00 m / min, vacuum on a substrate having a step around the land. Masking films AA to AD were laminated at a degree of 1000 Pa while peeling off the protective film. By laminating under reduced pressure, the pressure-sensitive adhesive layer of the masking film followed the step around the land portion, and no microbubbles were observed. Furthermore, the masking film was able to be formed on the photocrosslinkable resin layer flatly without undulation with respect to the substrate because the adhesive layer followed the step. In addition, a cleaning process was performed from above the masking film using a slightly sticky clean roller (registered trademark) (trade name: RY-501Z, manufactured by Rayon Kogyo Co., Ltd.) before the exposure. I couldn't see it.

  After the thinning treatment, a resist pattern was formed through steps (c), (g), and (d) as in Examples 1 to 4. When the photocrosslinkable resin layer tented on the land portion was observed, the photocrosslinkable resin layer was not broken or peeled in all the holes. As a result of observing the obtained resist pattern with an optical microscope, defects such as line thinning, disconnection, line thickening, and short-circuiting were not found in the pattern of line / space = 25/25 μm. In addition, in the steps around the land portion, no resolution failure due to line thickening due to light refraction such as light leakage was observed.

(Comparative Example 1)
A resist pattern was prepared in exactly the same manner as in Example 1, except that the masking film A was only a transparent support layer film (film thickness: 16 μm) made of a polyester film. Fine bubbles were not mixed between the photocrosslinkable resin layer after thinning and the transparent film, and the transparent film could be laminated flatly on the photocrosslinkable resin layer without undulations. However, when the cleaning treatment was performed from above the transparent film using a slightly sticky Clean Roller (registered trademark) (trade name: RY-501Z, manufactured by Rayon Kogyo Co., Ltd.) before the exposure, the transparent film was peeled off. Occurred. As a result, the surface of the photocrosslinkable resin layer after thinning is exposed, and there is a possibility that the photo tool is contaminated with scratches and foreign matters, adhesion exposure, and a resist pattern without defect is produced. Was extremely difficult.

(Comparative Example 2)
A resist pattern was prepared in exactly the same manner as in Example 5 except that the masking film AA was only a transparent support layer film (film thickness 16 μm) made of a polyester film. Even with the transparent film alone, even when laminating in a reduced-pressure atmosphere, there was a step around the land, so that the height difference could not be filled, and air bubbles were noticeably mixed. Thereby, the polymerization inhibition by oxygen occurred, and when there were large bubbles, disconnection of the resist was also confirmed. In addition, since the film was heat-pressed with a roll heated to 100 ° C., the photocrosslinkable resin layer after thinning was depressed into a concave shape around the level difference, and resolving failure due to significant light leakage occurred at that portion. .

  The present invention is widely used for producing a fine conductive pattern using a subtractive method, and can be used for a method of manufacturing a lead frame in addition to the printed wiring board described in the embodiments.

1 Photocrosslinkable resin layer (uncured part)
2 substrate 3 cured portion of photocrosslinkable resin layer 4 conductive layer 5 insulating substrate 6 transparent film 7 non-photosensitive alkali-soluble adhesive layer 8 masking film 9 curing of photocrosslinkable resin layer exposed in step (i) Part 10 hole

Claims (2)

  (A) a step of forming a photocrosslinkable resin layer on the substrate, (b) a step of thinning the photocrosslinkable resin layer, (f) a transparent film and a non-photosensitive alkali-soluble adhesive layer are laminated. A step of applying the masking film so that the non-photosensitive alkali-soluble adhesive layer is in contact with the photocrosslinkable resin layer, (c) an exposure step of the circuit pattern, (g) a step of removing the transparent film, (d) development A process for producing a resist pattern.   (A) a step of forming a photocrosslinkable resin layer on the substrate, (i) a step of exposing a part of the photocrosslinkable resin layer, (b ′) thinning of the photocrosslinkable resin layer other than the exposed region. A step of performing a treatment, (f ′) a step of attaching a masking film in which a transparent film and a non-photosensitive alkali-soluble adhesive layer are laminated so that the non-photosensitive alkali-soluble adhesive layer is in contact with the photocrosslinkable resin layer, (C) A circuit pattern exposure step, (g) a step of removing a transparent film, and (d) a development step.

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