JPH045182B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a photoresist forming laminate. More specifically, the present invention provides a photoresist that can produce highly accurate photoresists without impairing image reproducibility due to scratches on printed circuit boards and without causing peeling of the photosensitive composition layer during operation. The present invention relates to a method of manufacturing a laminate for resist formation.

Currently, a wide variety of image-forming photosensitive materials, such as liquid photosensitive materials, silk screen ink-like photosensitive materials, or generally A photosensitive material called dry film, which is supported in advance on a flexible support, is used.

By the way, among these methods, when laminating a liquid photosensitive material on a substrate, a method is usually used to coat it to the required thickness using a roll coater, doctor knife, etc. So,
In many cases, a dry film thickness of only about 2 to 3 μm can be obtained in a single coating operation, and even if an appropriate combination of conditions is used, the thickness is at most about 10 μm, so 30 to 50 μm is obtained.
If a film as thick as m is required, the steps of coating and drying must be repeated many times.

On the other hand, when using a photosensitive material supported on a flexible support in advance (hereinafter referred to as dry film), the substrate surface is pretreated to improve adhesion to the substrate surface. To,
This method has recently attracted attention because it is possible to form a photosensitive material layer with a desired thickness by an extremely simple operation of overlapping the exposed surfaces of the photosensitive material layers and pressing them together through a gap between hot rolls. Until now, there have been methods in which dry film is laminated directly on a substrate, image-forming exposure, and development are carried out (Japanese Patent Publication No. 45-25231), and an adhesive layer is provided on one surface of the dry film. A method of laminating the film onto a substrate through a film, exposing it to image formation, and developing it (Japanese Patent Application Laid-open No. 1973-
154363) have been proposed.

By the way, in order to accurately form a precise pattern on the surface of a printed circuit board, it is necessary to make the surface as flat as possible, but normally, no matter how carefully it is handled during the manufacturing process, minute irregularities and Scratches are inevitable. As the pattern becomes finer, these defects on the surface of the printed circuit board cause line breakage and deformation, resulting in an increase in the number of defective products.

On the other hand, when laminating a printed circuit board and a dry film, if the adhesive strength between the two is insufficient, peeling will occur during the steps of image forming exposure, development, and drying of the laminated body, making it impossible to obtain the desired photoresist plate. .
To prevent this, for example, as mentioned above, an adhesive layer is provided in advance on the surface of the dry film, but in this case, the adhesive layer is completely dry, so when laminating it with the printed circuit board, In addition, the adhesive layer must be pressed using a hot roll heated to 100° C. or higher, and the adhesive layer deteriorates during storage of the dry film, resulting in a decrease in adhesive strength.

Under these circumstances, the present inventors ensured the adhesion between the dry film and the printed circuit board,
Moreover, in order to develop a manufacturing method for a photoresist forming laminate that can exhibit excellent image reproducibility even if there are some irregularities or scratches on the surface of the printed circuit board, and therefore can provide a high yield of final products. As a result of extensive research, we discovered that prior to laminating a printed circuit board and a dry film, a liquid photosensitive composition containing an antihalation agent is applied onto the printed circuit board, and in a so-called half-dry state, which has not yet solidified. The inventors have discovered that the object can be achieved by pressing the dry film between rolls without heating it to a high temperature, and have accomplished the present invention.

That is, in the present invention, a liquid photosensitive composition containing an antihalation agent is applied onto a printed circuit board in an amount such that the layer thickness after drying is 1 to 8 μm, and then this liquid photosensitive composition is allowed to dry. After drying to
The present invention provides a method for manufacturing a laminate for forming a photoresist, which is characterized in that the adhesive is bonded while applying pressure at a temperature of 0.degree. C. or lower.

Materials for the substrate used in the method of the present invention include:
Materials commonly used as substrates for printed circuits and other electronic components, such as metals such as copper and aluminum, silicon, titanium oxide, tantalum oxide, Bakelite, glass, epoxy resin, polyimide,
It can be arbitrarily selected from insulating materials such as paper and phenol resin, and materials laminated with copper, silver, aluminum, etc. on the surface of these materials.

Further, the liquid photosensitive composition applied to the surface of the substrate may be either a negative type or a positive type, that is, a photocurable composition or a photodegradable composition. Examples of photocurable compositions include photocrosslinkable polymers such as cinnamate esters of high molecular weight polyols, polyvinyl cinnamate, and polyvinylanisyl acetophenone, polyacrylic acid amide, polyol polymers,
Photocurable compositions such as compositions that combine gelatin, etc. with dichromate metal salts, diazo compounds, azide compounds, etc., compositions that consist of cyclized rubber and bisazide, or compositions that blend these with a small amount of epoxy acrylate. I can give things away.

However, particularly preferred are methyl methacrylate/methyl acrylate copolymers, methyl methacrylate/styrene copolymers, ethyl methacrylate/styrene copolymers, methyl acrylate/acrylonitrile copolymers, ethyl acrylate/acrylonitrile copolymers. Copolymer, methyl acrylate/styrene/acrylonitrile copolymer, methyl acrylate/butyl methacrylate copolymer, ethyl acrylate/butyl methacrylate copolymer, methyl methacrylate/acrylic acid copolymer, methyl methacrylate / β-hydroxyethyl acrylate copolymer, methyl methacrylate / β-hydroxypropyl acrylate / methacrylic acid copolymer, poly (methacrylic acid / epoxy acrylate), poly (methacrylic acid / epoxy acrylate / methacrylic acid), or these It is mainly composed of a copolymer of at least one of the following compounds and polyacrylated urethane, and polyalkylene glycol diacrylate or dimethacrylate (average degree of polymerization n = 2 to 200), polyethylene glycol diacrylate or dimethacrylate ( n=1~200),
Polyethylene glycol monoacrylate or monomethacrylate (n = 1 to 200), urethane diacrylate or dimethacrylate, polyalkylene diamine diacrylate or dimethacrylate (n = 1 to 10), epoxy acrylate (n = 1 to
10) The active ingredient is an acrylic photopolymerizable compound or an acrylic photopolymerizable mixture such as pentaerythritol triacrylate or trimethacrylate.

This liquid photosensitive composition usually contains, in addition to the above-mentioned active ingredients, photopolymerization initiators such as anthraquinone, methylanthraquinone, chloroanthraquinone, and
- Ethyl anthraquinone, 2-tert-butylanthraquinone, benzanthraquinone, benzoin, benzoin isopropyl ether, benzyl, benzophenone, Michler's ketone, etc. Contains hydroquinone, methylhydroquinone, etc. as a thermal polymerization inhibitor, but in addition, coloring as necessary It may also contain additives, plasticizers, etc. Furthermore, as an example of a positive type, an alkali-developable type containing a combination of orthobenzoquinone diazide or 1,2-naphthoquinone diazide and an alkali-soluble phenol novolac resin as an active ingredient (Japanese Patent Publication No. 37-18015
In place of the above-mentioned alkali-soluble phenol novolak resin,
Examples include those using a maleic anhydride copolymer (Japanese Patent Publication No. 37-3627).

In the present invention, it is necessary to include an antihalation agent in the liquid photosensitive composition. This is added to improve the resolution and image reproducibility after dry films are laminated, and it is thereby possible to accurately reproduce fine patterns. The antihalation agent may be one that exhibits absorption in the photosensitive wavelength range of 280 to 430 nm, such as acridine dyes, aniline black, anthraquinone dyes, azine dyes, azo dyes, azomethine dyes, benzoquinone dyes, naphthoquinone dyes, indigoid dyes, Indophenols, indoanilines, indamines, leuco vat dye esters, naphtholimide dyes, nigrosine and indiulin, nitro and nitroso dyes, oxazine and dioxazine dyes, oxidation dyes, phthalocyanine dyes, polymethine dyes, quinophthalone dyes, sulfur dyes, triarylmethane and dyes such as diarylmethane dyes, thiazine dyes, thiazole dyes, and xanthene dyes; inorganic and organic pigments; and phenyl salicylate, benzophenone, benzotriazole, and acrylate ultraviolet absorbers. This antihalation agent is 0.001 to 10% by weight, preferably 0.05% by weight based on the total weight of the resin forming the surface protective layer.
It is added in a proportion of ~2% by weight.

The resin-forming components in the liquid photosensitive composition of the present invention include, in order to enhance the adhesion between the printed circuit board and the dry film, and to make the solubility in the developer during development the same as that of the dry film. It is preferable to select one having the same or similar composition to the photosensitive resin component used in the dry film.

This liquid photosensitive composition can be prepared by dissolving each of the above-described components in a suitable solvent such as acetone, methyl ethyl ketone, trichloroethane, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, triethylene glycol diacetate, etc. Prepare. The amount of solvent used in this case must be such that it has sufficient fluidity to apply the liquid photosensitive composition to the printed circuit board and that it does not flow down after application. It is selected within the range of 50 to 95% by weight based on the total amount of the composition.

Next, as a dry film to be laminated on a printed circuit board via this liquid photosensitive composition layer,
A photosensitive resin layer made of a photosensitive composition is laminated on a material that is generally well known as a dry film for manufacturing electronic components, that is, a flexible support, and a protective film layer is further applied thereon as desired. You can arbitrarily choose and use them. As the above-mentioned flexible support, metal foil, polyamide, polyolefin, polyester, polyvinyl chloride, paper, etc. are used, but transparent materials are advantageous in that they do not need to be removed during image-forming exposure. Polyethylene terephthalate is preferred. Furthermore, the photosensitive resin layer is not particularly limited, and may be any material as long as it becomes solvent insoluble or, conversely, solvent soluble when sensitive to light. An example of such a composition is the photosensitive composition exemplified as the resin component of the liquid sensitive composition.

To suitably carry out the method of the present invention, a liquid photosensitive composition is coated on both sides of a printed circuit board in a light-blocked zone using, for example, a double-sided coater.
The coating amount is selected within the range resulting in a layer thickness of 1 to 8 μm after drying. The layer thickness after drying is
If it is less than 1 μm, the adhesion will not be improved and the unevenness and scratches on the surface of the printed circuit board will be insufficiently covered.
If it is thicker than 8 μm, not only will it take a long time for image-forming exposure, but also the residual solvent during lamination of the flexible photosensitive material will soften the material and make it difficult to cure, resulting in poor tenting properties and halation. This is not preferable as it makes it easier.

The printed circuit board coated with the liquid photosensitive composition is then dried to such an extent that the liquid photosensitive composition is not completely solidified, that is, to a half-dry state. This drying is carried out at a temperature of 60 to 80°C, passing an inert gas as necessary, until the solvent content in the composition is reduced.
This is done until it reaches 10-30% by weight. If the solvent content is less than 10% by weight, sufficient adhesion will not be obtained during subsequent lamination with the dry film, and if the solvent content is more than 30% by weight, the bonded dry film will be damaged. The dry film may peel off or the remaining solvent may soften the dry film, resulting in deterioration of tenting properties.

Note that the wet coating thickness of the liquid photosensitive composition is 2 to 2
When the thickness is about 3 μm, the drying speed is fast, so the required conditions can be achieved without any particular drying treatment.

In the method of the present invention, when laminating a printed circuit board and a dry film, there is no need to heat it to a high temperature as in the conventional method, and the pressure roller may be maintained at 70° C. or lower, preferably at room temperature.

In this manner, a laminate for forming a photoresist can be continuously manufactured by the method of the present invention.

A photoresist pattern can be obtained from the laminate obtained according to the present invention by using image forming exposure and development methods that are commonly used in forming photoresists. However, when developing, use a developer that can dissolve the unexposed areas of the dry film (exposed areas in the case of a positive type) and the unexposed areas of the liquid photosensitive composition layer (the exposed areas in the case of a positive type) at the same time. is necessary. This developing solution is appropriately selected depending on the type of photosensitive composition forming the dry film and the liquid photosensitive composition layer, but is usually an aqueous alkali solution, alcohols, ketones, hydrogen carbonates, or halogenated hydrocarbons. or mixtures thereof.

According to the method of the present invention, by appropriately selecting the photosensitive composition that forms the liquid photosensitive composition layer, sufficient strength can be achieved not only for currently commercially available dry films but also for dry films that have poor direct adhesion by thermocompression bonding. It can be laminated onto the surface of a substrate using a method that covers and hides scratches and dents on the solid surface.In addition, it is possible to cover the openings during through-hole processing when laminating with conventional dry film alone. In the process of tenting (usually called tenting), a considerable surface area is required for the film holding part, and it is necessary to provide a so-called land that is larger than the diameter of the opening. Therefore, there is an advantage that the wiring density of the printed wiring board can be further improved. Furthermore, in the method of the present invention, the liquid photosensitive composition layer also serves as an adhesive layer and improves the adhesion between the dry film and the printed circuit board. Peeling of both during the operation can be significantly reduced, and since the liquid photosensitive composition layer is also removed at the same time during the development process, phenomena such as undercut phenomena that impair resolution do not occur.
Therefore, the yield of products can be significantly increased compared to conventional methods.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 200g of photosensitive layer portion of photosensitive dry film “Odale 5010” (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.)
was dissolved in 800 g of ethylene glycol monoethyl ether acetate, and 1 g of ethyl violet was added thereto as an antihalation agent and dissolved to obtain a liquid photosensitive composition.

This liquid photosensitive composition was applied to both sides of the copper-clad laminate using a double-sided coater, and dried at 80°C for 1 minute to form a coating film with a thickness of 4 μm and a residual solvent content of approximately 25% by weight. A photosensitive dry film "O'Deil 5010" was laminated at a temperature of 60°C and under pressure at a speed of 1.0 m/min. After leaving it for 10 minutes, a 3 kW ultra-high pressure mercury lamp was used as the light source, and an exposure dose of 80 mJ/cm ² was applied through a mask with a fine line pattern, until the liquid temperature reached 35
The film was developed by spraying a 2% aqueous sodium carbonate solution at a temperature of 1.4 Kg/cm ² for 80 seconds. The unexposed portions of the photosensitive dry film and the coating film of the liquid photosensitive composition on the lower surface thereof were simultaneously developed and removed, and an image faithful to the mask was formed.

Example 1 Part 200 of the photosensitive layer of the photosensitive dry film “Odale 5020” (trade name, manufactured by Tokyo Ohka Kogyo KK)
g for ethylene glycol monoethyl acetate
A liquid photosensitive composition was prepared by dissolving the mixture in 800 g and adding 0.5 g of methylene blue as an antihalation agent. Next, this liquid photosensitive composition is applied to both sides of the copper-clad laminate using a double-sided coater,
Dry at 80℃ for 1 minute, remaining solvent approximately 20% by weight, film thickness
A 2μm coating film is formed, and a photosensitive dry film "O'Deil 5020" is applied on top of it at a temperature of 70℃.
The lamination was carried out under pressure at a temperature of 1.5 m/min at a temperature of 1.5 m/min.

The photoresist forming laminate thus obtained was irradiated with 3 kW ultra-high pressure mercury as a light source through a printed wiring pattern mask at an exposure dose of 80 mJ/cm ² , and then 1,1,1-trichloroethane was used. Developed. At this time, the liquid photosensitive composition and coating film on the lower surface were removed at the same time as the unexposed portion of the dry film.

Furthermore, when the pattern thus obtained was etched, a faithful circuit was obtained. Figure 1A shows a width of about 100 μm on the copper surface.
This is an example of a pattern with a drawing line formed over a flaw with a depth of 15 to 20 μm, but when this is etched, a complete wiring part is clearly formed as shown in Figure 1B. It is formed.

On the other hand, when similar treatment was performed using a photosensitive dry film "O'Deil 5020" directly laminated on both sides of a copper-clad laminate without applying a liquid photosensitive composition, the second As shown in the figure, the wiring portion of A before etching was eroded and disconnected after etching.

[Brief explanation of drawings]

FIG. 1 is an enlarged perspective view showing the state of printed wiring before etching treatment A and after etching treatment B using the photoresist forming laminate obtained by the method of the present invention, and FIG. 2 shows the corresponding state obtained by the conventional method. It is an enlarged perspective view.

Claims (1)

[Claims] 1. A liquid photosensitive composition containing an antihalation agent is applied onto a printed circuit board so that the layer thickness after drying is 1 to 8 μm.
The liquid photosensitive composition is then dried until it is half-dry, and then a dry film is laminated thereon and bonded under pressure at a temperature of 70°C or less. A method for manufacturing a laminate for resist formation.