JPH0531438A - Formation of resist film - Google Patents

Abstract

PURPOSE:To provide the method for forming the resist film which allows the formation of a thin film, the control of a film thickness with good accuracy and the application to a large substrate and can be easily executed. CONSTITUTION:This method for forming the resist film consists in fixing a material 1 to be coated into a chamber 2, introducing a resist liquid 3 into the chamber 2 to immerse the material 1 to be coated into the resist liquid 3, and discharging the resist liquid 3 to the outside of the chamber 2, thereby applying the resist liquid 3 on the material 1 to be coated, then drying the material 1 coated with the resist liquid 3. Since the material 1 to be coated is fixed, the resist liquid 3 can be applied on the material 1 to be coated without applying vibrations and oscillations thereto. The film thickness is thus controlled with the good accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist film used in the manufacturing process of printed wiring boards.

[0002]

2. Description of the Related Art Conventionally, a screen printing method, a dry film method, a roll coater method, a method of forming a resist film used in a manufacturing process of a printed wiring board,
Spin coating method, electrodeposition method and the like are known. However, there is a problem in forming a resist film, which is a thin film and has a high film thickness accuracy, which is required for manufacturing a highly accurate printed wiring board, by the above conventional method. That is, it is difficult for the screen printing method of (1) to accurately control the film thickness of the resist film, and the dry film method of (1) is difficult to form a thin film because a previously formed film is used, and the roll coater method of As with the screen printing method, it is difficult to control the film thickness of the resist film with high precision, the spin coating method is difficult to apply to a large substrate, and the electrodeposition method is difficult to control the electrodeposition liquid. It is the current situation.

Therefore, the inventors of the present application apply the resist solution to the entire surface of the object to be coated by immersing the object to be coated in the resist solution filled in the tank and then pulling it up to form a resist film. The method of forming was investigated. However, in this method, there is a limit in raising and lowering the coated object without giving vibration or shaking, and thus there is a limit in accurately controlling the resist film thickness.

[0004]

The problem to be solved by the present invention is to form a thin film, to control the film thickness with high accuracy, to apply it to a large substrate, and to implement it easily. Is to find out how to form.

[0005]

According to the present invention, after fixing an object to be coated in a tank, a resist solution is introduced into the tank to immerse the object in the resist solution, A method for forming a resist film is characterized in that the resist solution is applied to the object to be coated by discharging the resist solution to the outside of the bath, and then the object to be coated with the resist solution is dried.

The bath used in the present invention may be any bath made of a material having solvent resistance enough to withstand the resist solution,
The shape is not particularly limited.

In the present invention, the object to be coated to form the resist film is a substrate material used in a usual printed wiring board, such as a glass epoxy copper clad laminate or a paper phenol copper clad laminate. In the case where the object to be coated is a substrate having through holes, it is general that the surface of the insulating substrate is covered with a metal layer by a method such as plating. Then, a resist film is formed so as to cover the entire portion including the through holes.

In the present invention, the method of fixing the object to be coated in the bath is not particularly limited, and for example, one side is sandwiched by a jig and fixed, or a hole for fixing is formed in the object to be coated. It may be carried out by a method of fixing a wire such as a metal wire through the hole.

A photosensitive resist solution can be applied to the resist solution used in the present invention, and there are a positive type and a negative type in the photosensitive resist solution, but any type can be used in the present invention. The composition of the photosensitive resist solution is not particularly limited, and any conventionally used etching resist or solder resist can be used. The viscosity of the resist solution is not particularly limited, but it is 10 to 10 when it is measured by a No. 1 to No. 3 rotor using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) and a rotation speed of 60 rpm. 1500cps preferred, 50-50
More preferably, it is in the range of 0 cps. Similarly, although not particularly limited, the thixotropy value of the photosensitive resist solution is preferably in the range of 1.2 to 9.0, and more preferably in the range of 2.0 to 6.0. The thixotropy value of this resist solution is expressed by the viscosity ratio of the two, which was obtained by measuring the above-mentioned viscosity at a high speed of 60 rpm and a low speed of 6 rpm. That is, the thixotropic value in the present invention is a value represented by the following formula.

Thixotropic value = viscosity at 6 rpm / 60
Viscosity at rpm In the present invention, the method for introducing the resist solution and discharging the resist solution is not particularly limited, and it may be performed by a free fall method or a method using a pump.

[0011]

[Function] It is necessary to introduce the resist solution into the tank in which the object to be coated is fixed, immerse the object to be coated in the resist solution, and then to discharge the resist solution out of the tank. It works to apply the resist solution without shaking or shaking. The ability to apply the resist solution without giving vibration or shaking to the object to be coated is effective in controlling the obtained film thickness with high accuracy.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of a resist liquid coating apparatus used in the method for forming a resist film of the present invention. In FIG. 1, an object to be coated 1 is fixed in a tank 2 by a sandwiching jig 8, and a resist solution 3 is introduced into an introducing pipe 5 by operating an introducing valve 4.
It is configured to be introduced into the tank 2 through. Further, the resist liquid 3 is discharged from the discharge pipe 6 by operating the discharge valve 7.
It is configured to be discharged to the outside of the tank 2 through.

The procedure for applying the resist solution 3 to the article 1 using the resist solution application apparatus constructed as described above is as follows. The resist liquid 3 is injected into the empty tank 2 through the introduction pipe 5 to the upper level 9 where the liquid surface thereof reaches the upper part of the fixed object 1 to be coated.
Here, the rate of injecting the resist solution 3 is not particularly limited, but it is introduced by operating the introducing valve 4 so that the liquid surface does not foam. Drain valve 7 for resist liquid 3 in tank 2
Is discharged to the outside of the tank 2 through the discharge pipe 6, and the liquid level of the resist liquid 3 is lower than the lower part of the article 1 to be coated.
Lower to 0. The descending speed of the liquid surface at this time is not particularly limited, but is preferably 10 to 500 cm / min, and more preferably 20 to 100 cm / min. Control of the descending speed of the liquid surface can be performed by adjusting the discharge valve 7 or using a metering pump (not shown).

By drying the coating object 1 coated with the resist solution 3 thus obtained, the coating object 1 having a resist film formed thereon is obtained.

According to the above-mentioned method of the present invention, the viscosity of the resist solution 3, the thixotropic value, or the rate of lowering of the liquid surface of the resist solution 3 due to the discharge of the resist solution 3 is adjusted to adjust the object to be coated. It is possible to adjust the thickness of the resist solution 3 applied to the No. For example, by adjusting the viscosity of the resist solution 3, the thixotropy value, and the descending speed of the liquid surface accompanying the discharge of the resist solution 3 within the above-mentioned range, it is possible to form a thin film of several μm level.

The object to be coated 1 on which the resist film has been formed as described above is exposed to ultraviolet rays using an appropriate mask pattern when the resist film is an etching resist, and then developed to develop an unnecessary portion of the resist film. Can be removed and etching can be performed to form a desired pattern. According to the present invention, it is possible to form a resist film which is a thin film having a level of several μm, so that a very fine pattern can be accurately formed.

Next, a specific example of manufacturing a printed wiring board by actually applying the method for forming a resist film according to the present invention will be described.

(Example 1) 300 mm x 30 as the object to be coated 1
A 0 mm x 1.3 mm glass epoxy copper clad laminate was used.
The object 1 is sandwiched by a sandwiching jig 8 fixed on the upper portion of the tank 2 and fixed, and then the etching resist liquid 3 is fixed on the surface of the etching resist liquid 3 through an introducing pipe 5 in the empty tank 2. It was injected up to the upper level 9 which reaches the upper part or more of the coated object 1. Next, the resist liquid 3 filled in the tank 2 is discharged to the outside of the tank 2 through the discharge pipe 6 by operating the discharge valve 7, and the liquid level of the resist liquid 3 is lower than the lower part of the object 1 to be coated. Lowered. The descent speed of the liquid surface at this time is 50
It was cm / min. The viscosity of the photosensitive resist solution used at this time was 160 cps, and the thixotropy value was 4.5.

In this way, the object 1 to be coated with the resist solution 3 is obtained, and the object 1 to be coated with the resist solution 3 is dried at 90 ° C. to obtain a thickness of 8 μm.
An object to be coated 1 having a resist film of m was obtained.

After that, the mask pattern was used to expose it to ultraviolet rays, and the resist film in the unnecessary portion was removed by development, and etching was performed to form a wiring pattern.
Next, the resist film on the wiring pattern was peeled off and removed with a NaOH solution having a content of 3% by weight to obtain a printed wiring board.

Thickness of 8 μ formed in the above embodiment
When the variation in the thickness of the resist film of m was examined, all the film thicknesses were in the range of 7.2 to 8.8 μm. On the other hand, as a comparison, when the variation in the thickness of the resist film having a thickness of 8 μm formed by the method of moving the substrate up and down in the photosensitive resist solution was examined, the film thickness varied in the range of 6.4 to 9.6 μm. From these results, it was confirmed that according to the present invention, the film thickness of the etching resist film can be controlled with high accuracy.

[0022]

According to the method of forming a resist film of the present invention, a thin film can be formed, and the film thickness can be controlled accurately.
Since it can be applied to a large substrate and has an effect that it can be easily implemented, it is useful as a method for forming a resist film used in a manufacturing process of a printed wiring board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a resist solution coating apparatus used in a method for forming a resist film of the present invention.

[Explanation of symbols]

 1 coating object 2 tank 3 resist liquid 4 introduction valve 5 introduction pipe 6 discharge pipe 7 discharge valve 8 sandwiching jig 8 9 upper level 10 lower level

Claims (1)

Claims: 1. An object to be coated is fixed in a tank, a resist solution is introduced into the tank to immerse the object in the resist solution, and A method for forming a resist film, which comprises applying the resist solution to the object to be coated by discharging the object to the outside of the bath, and then drying the object to be coated with the resist solution.