JPH08254832A - Resist developing method - Google Patents

Abstract

PURPOSE: To obtain a developing method by which a protective layer can be removed without physically removing the protective layer before developing a resist layer and the development of the resist layer is easily controlled, by exposing the resist layer for a pattern, dissolving the protective layer with a neutral or acid water-base medium, and developing the resist layer to form the resist pattern. CONSTITUTION: A liquid photosetting resist is applied to form resist layers 3 on a printed circuit board base body 1 both surface of which are coated with copper 2. Then a material which can be dissolved in a neutral or acid water-base medium, for example, a polyvinylalcohol-vinyl acetate mixture is applied to form protective layers 4. The whole layers are heated to remove the solvent in the resist layers 3 and the protective layers 4, then dried and exposed to light for a desired pattern by using a mask or irradiating with controlled laser light. The printed circuit board base body 1 is disposed on a conveyer and cleaned with water in a removing process of the protective layers to dissolve the protective layers 4, and then the printed circuit board base body 1 is continuously subjected to a developing process of the resist layers to develop the resist layers 3 with a developer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resist developing method. More specifically, the present invention relates to a resist developing method used when forming a pattern on a printed wiring board substrate or the like.

[0002]

2. Description of the Related Art Conventionally, a dry film or a liquid resist material has been used in etching for forming wiring on a printed wiring board or the like. These resist materials are used as a resist layer by coating on a printed wiring board substrate or the like. Further, a transparent protective layer is formed on the resist layer in order to accelerate the curing reaction by light. The role of this protective layer is (1) prevention of insufficient curing of the resist layer due to oxygen obstructing the curing during the curing reaction (2) prevention of adhesion of dust to the resist layer and damage of the resist layer It is prevention.

[0003]

The protective layer is removed by physically peeling it off or by dissolving it in an actual solution used for developing the resist layer and removing it. However, the method of physically peeling off the protective layer increases the number of steps and requires manpower, which causes a cost increase. On the other hand, in the method of dissolving and removing with a developing solution, since it is performed at the same time as the development of the resist layer, it is necessary to develop for a long time. Furthermore, the formed resist layer and protective layer are not strictly uniform in thickness, but have variations in thickness. Therefore, when the resist layer and the protective layer are dissolved, in order to prevent the resist layer from remaining, it is necessary to develop the resist layer and the protective layer in accordance with the thick part of the two layers, and therefore a thin resist pattern is formed. It was difficult to develop.

[0004]

According to the present invention, a resist layer is formed on a substrate, and a protective layer soluble in a neutral or acidic aqueous medium is formed on the resist layer. And irradiating the protective layer with light to expose a desired pattern to the resist layer, dissolving the protective layer in a neutral to acidic aqueous medium, and developing the resist layer with a predetermined developing solution to form a resist pattern. A resist developing method is provided.

The substrate that can be used in the present invention is not particularly limited as long as it is a substrate for which it is desired to form a resist pattern. For example, a printed wiring board substrate, a multi-chip module (MCM), etc. may be mentioned. Next, any known resist material can be used for the resist layer of the present invention. Examples of the resist material include aromatic diazonium salt-based, o-quinonediazide-based, and bisazide-based photodegradable resist materials, cinnamic acid ester-based photodimerization-type resist materials, unsaturated polyesters, epoxy acrylates, and the like. A photopolymerizable resist material comprising poval, polyamide, polymethacrylate, etc. as a prepolymer or binder polymer such as urethane acrylate, various acrylate and methacrylate monomers, and a photopolymerization initiator (for example, benzophenone, Michler's ketone, etc.) Can be mentioned. If necessary, the resist material may include a dye (leuco crystal violet, tribromomethyl sulfone, etc.), an adhesion promoter (5-amino-1,11-tetrazole, etc.), and a solvent (methyl ethyl ketone, isopropyl alcohol, etc.). May be added. Examples of the shape of the resist material include a dry film type and a liquid type. The thickness of the resist layer is
The thickness is preferably 0.3 to 40 μm.

Here, the resist layer may have a two-layer structure. That is, it has a structure in which a resist layer having high sensitivity is laminated on the base material side, and a resist layer having low sensitivity is laminated thereon. With this two-layer structure, a fine resist pattern that cannot be formed by a resist layer having low sensitivity can be formed by using a resist layer having high sensitivity. Further, the wavelengths of light for curing both the highly sensitive resist layer and the less sensitive resist layer may be the same or different. If a resist material that cures at different wavelengths of light is used for both layers, both layers can be selectively cured.

The above two-layer resist layer is exposed as follows, for example. Here, a case of exposing a resist layer using a resist material that cures at different wavelengths of light will be described. First, for the highly sensitive resist layer,
Light having a wavelength that can cure the resist layer exposes all patterns including fine patterns. Next, a pattern other than a fine pattern is exposed on the resist layer having low sensitivity by light having a wavelength that can cure the resist layer.

A resist layer having a high sensitivity is likely to be insufficiently cured because it is easily polymerized with oxygen during the curing reaction, and the exposure of the resist layer is likely to be insufficient due to the adhesion of dust and the generation of scratches. . Therefore, when only a highly sensitive resist layer is used for forming a resist pattern, a fine resist pattern cannot be formed.

As a method for laminating the resist layer, any known method can be used. For example, when a dry film is used, the film can be laminated on the surface of the base material by a method such as thermocompression bonding. On the other hand, when a liquid resist material is used, it can be laminated by applying it using a dip coater or the like. Next, a protective layer is formed on the resist layer. The protective layer that can be used in the present invention is not particularly limited as long as it can be dissolved in a neutral to acidic aqueous medium. Here, neutral to acidic means pH.
This means that the pH is 8.5 or less, and when the pH is higher than 8.5, the resist layer is also dissolved, which is not preferable.
Further, the pH is preferably in the range of 6 to 8.5 in consideration of the post-treatment of the waste liquid. Specific examples of materials that can be used for the protective layer include polyvinyl alcohol and vinyl acetate. Further, it is more preferable to use a mixture of polyvinyl alcohol and vinyl acetate because the oxygen barrier property is improved. The thickness of the protective layer is 1 to 10 μm, preferably 2
Is about 3 μm. If it is less than 1 μm, it is not preferable because sufficient oxygen barrier property cannot be obtained.
If it is larger, it takes time to remove the protective layer, which is not preferable.

The method for laminating the protective layer is not particularly limited, and may be applied by using a spin coater, a roller coater, a dip coater, a spray or the like. It is also possible to stack them on the dry film in advance.
Next, the resist layer and the protective layer are irradiated with light to expose the resist layer with a desired pattern. The light used for exposure is
Light having a wavelength corresponding to the resist layer used can be used, and visible light, ultraviolet light, infrared light, or the like can be used.

Further, the protective layer is removed by dissolving it in an aqueous medium of neutral to acidic, preferably pH 6 to 8.5. The aqueous medium that can be used in the present invention means an aqueous medium whose pH is adjusted by appropriately adding acid or alkali to water. In addition, an additive such as an acrylic or silicone antifoaming agent may be added to the aqueous medium within a neutral or acidic range. The removal method is not particularly limited,
Examples include batch type and spray type.

Next, the resist layer is developed and stripped. The developing solution is not particularly limited, and a developing solution corresponding to the used resist layer is used. For example, an alkaline aqueous solution of sodium carbonate, sodium hydroxide, potassium hydroxide or the like, or an organic solvent such as 1,1,1-trichloroethane or methylene chloride can be used. Here, it is more preferable that the removal of the protective layer and the peeling of the resist layer are continuously performed by using a conveyor or the like because the developing time can be shortened.

[0013]

According to the resist developing method of the present invention, a resist layer is formed on a substrate, a protective layer soluble in a neutral or acidic aqueous medium is formed on the resist layer, and the resist layer and the protective layer are formed. The resist pattern is formed by exposing the resist layer to a desired pattern by irradiating light, dissolving the protective layer in a neutral to acidic aqueous medium, and developing the resist layer with a predetermined developing solution. Therefore, the protective layer can be removed before the development of the resist layer without physically removing the protective layer, and a development method in which the development of the resist layer can be easily controlled is provided.

[0014]

【Example】

Example 1 A liquid photocurable resist was applied to a double-sided copper-clad laminate in which copper 2 was laminated on both sides of a printed wiring board substrate 1 with a dip coater to form a resist layer 3 having a layer thickness of 4 to 6 μm.

Next, a polyvinyl alcohol / vinyl acetate (polyvinyl alcohol: vinyl acetate = 6: 4) mixture was applied by a dip coater to form a protective layer 4 having a layer thickness of 2 to 4 μm.
Was formed. Through the above steps, as shown in FIG. 1, a printed wiring board base material 1 having copper 2, a resist layer 3 and a protective layer 4 formed on both surfaces thereof was obtained.

The resist layer 3 and the protective layer 4 are heated by heating the whole.
After the solvent was removed by drying, the mask or a controlled laser beam was irradiated to expose a desired pattern. Further, the printed wiring board substrate 1 is placed on the conveyor 5 of the apparatus shown in FIG. 2, and in the protective layer removing step 6, the protective layer is dissolved and removed by washing with water, and the printed wiring is continuously printed. By subjecting the plate substrate 1 to the resist layer developing step 7, the resist layer was developed with a developing solution (0.5% sodium carbonate aqueous solution). In FIG. 2, the copper 2, the resist layer 3, and the protective layer 4 are omitted for simplicity. Thereafter, the developer was removed by washing with water to obtain a printed wiring board base material having a desired resist pattern formed on the resist layer.

In this embodiment, the developing time was 20 seconds and the minimum pattern width that could be resolved was 40 μm. Comparative Example A resist pattern was formed in the same manner as in Example 1 except that the conventionally used polyvinyl alcohol was used as the protective layer. The resist pattern was formed by using the apparatus shown in FIG. 3 for simultaneously dissolving the protective layer and developing the resist layer. In FIG. 3, 8 indicates a protective layer removing step and a resist layer developing step. Further, in FIG. 3, the copper 2, the resist layer 3, and the protective layer 4 are omitted for simplicity.

In the comparative example, the developing time was 60 seconds and the minimum pattern width that could be resolved was 80 μm. As is clear from the above Examples and Comparative Examples, it was possible to realize a great reduction in the development time and a finer minimum resolution pattern width.

[0019]

According to the resist developing method of the present invention, a resist layer is formed on a substrate, and a protective layer soluble in a neutral or acidic aqueous medium is formed on the resist layer. Irradiate the protective layer with light to expose a desired pattern on the resist layer, dissolve the protective layer in a neutral to acidic aqueous medium,
Since the resist pattern is formed by developing the resist layer with a predetermined developing solution, the protective layer can be removed before the development of the resist layer without physically removing the protective layer. It is possible to provide a developing method that is easy to control.

Furthermore, since the protective layer is made of a material that can be dissolved in an aqueous medium having a pH of 6 to 8.5, it is possible to easily treat the waste liquid generated when the protective layer is removed. Also,
By continuously dissolving the protective layer and developing the resist layer, the developing time can be further shortened. Further, the protective layer is made of polyvinyl alcohol, vinyl acetate, or a mixture of polyvinyl alcohol and vinyl acetate, whereby the oxygen barrier property can be further improved.

Further, since the resist layer is composed of two layers, the upper layer is a resist layer having low sensitivity and the lower layer is a resist layer having high sensitivity, it is possible to achieve finer patterns to be formed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a printed wiring board in which a protective layer and a resist layer are laminated in an example.

FIG. 2 is a schematic view of a conveyor for dissolving a protective layer and developing a resist layer used in Examples.

FIG. 3 is a schematic view of a conveyer used in a comparative example for dissolving a protective layer and developing a resist layer.

[Explanation of symbols]

 1 Printed Wiring Board Base Material 2 Copper 3 Resist Layer 4 Protective Layer 5 Conveyor 6 Protective Layer Removing Step 7 Resist Layer Developing Step 8 Protective Film Removing and Resist Layer Developing Step

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area H05K 3/06 H05K 3/06 G

Claims (5)

[Claims] 1. A resist layer is formed on a base material, a protective layer soluble in a neutral to acidic aqueous medium is formed on the resist layer, and the resist layer and the protective layer are irradiated with light to form a resist layer. A resist development method comprising forming a resist pattern by exposing a desired pattern to a solution, dissolving the protective layer in a neutral or acidic aqueous medium, and developing the resist layer with a predetermined developing solution. 2. The resist developing method according to claim 1, wherein the protective layer is made of a material which can be dissolved in an aqueous medium having a pH of 6 to 8.5. 3. The resist developing method according to claim 1 or 2, which comprises continuously dissolving the protective layer and developing the resist layer. 4. The resist developing method according to claim 1, wherein the protective layer is made of polyvinyl alcohol, vinyl acetate, or a mixture of polyvinyl alcohol and vinyl acetate. 5. The resist developing method according to claim 1, wherein the resist layer is composed of two layers, the upper layer is a resist layer having low sensitivity, and the lower layer is a resist layer having high sensitivity.