JPH0193743A - Formation of mask film - Google Patents

Abstract

PURPOSE:To use a normal image forming film and to correct the line width on the same image forming condition by exposing an unexposed film as prescribed by an image forming machine after exposing it to safelight. CONSTITUTION:The unexposed film is exposed as desired by the image forming machine after being exposed as prescribed with safelight whose wavelength is on the outside of the sensitivity on the spectral sensitivity curve of the film and this film is developed to generate a mask film. For example, when masks having line width A (for example, 100mum) and ling width B (for example, 110mum) will be formed, the unexposed film is exposed as prescribed by the image forming machine so that the width A is obtained and the film is developed to form a mask having the width A. The exposure condition of safelight by which the extent of correction of the line width is C (for example, 10mum) is obtained and the unexposed film is exposed on this condition and is exposed on the same condition as formation of the mask having the width A by the image forming machine and is developed to form a mask which has a circuit pattern having the width B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a mask film used in devices such as circuit boards.

[Conventional technology]

Conventionally, drawing of mask films in the field of precision photography used for circuit boards, etc., was done using laser drawing machines with precisely adjusted light intensity, so when drawing mask films with the same circuit pattern, they were always drawn on the same line. Only circuit patterns with width can be obtained. Therefore, when forming multiple mask films that differ only in line width, it is necessary to use unexposed films with different spectral sensitivity curves or to readjust the light intensity of the drawing machine each time to a predetermined light intensity. After making adjustments, I started drawing.

[Problem that the invention seeks to solve]

In the above-mentioned conventional method for forming mask films with circuit patterns that differ only in line width, when changing the type of film, it is necessary to use a developing solution that matches the characteristics of each emulsion. This method has the disadvantage that multiple automatic processors are required, which complicates management and operation. Further, when adjusting the light amount of the drawing machine, it is very difficult to make one-time adjustment, and there is a drawback that fine adjustment takes time.

An object of the present invention is to provide a method for forming a mask film that can easily form a plurality of mask films having circuit patterns that differ only in line width.

[Means for solving problems]

The method for forming a mask film of the present invention involves exposing an unexposed film to a predetermined amount of light using a safelight having a wavelength outside the chromatic sensitivity on the spectral sensitivity curve of the film, and then performing predetermined exposure using a drawing machine and developing the film. It is something to be processed.

If an unexposed film is exposed with a safelight having a wavelength outside the chromatic sensitivity on the spectral sensitivity curve of the unexposed film, and then a predetermined exposure is performed using an image forming machine and processing is performed, the result will be higher than when processed using the image forming apparatus alone. The line width of the circuit pattern becomes larger. Therefore, by controlling the expansion of the line width (hereinafter referred to as the correction amount) due to safelight exposure, it is possible to easily form a mask film in which a circuit pattern having a desired line width is formed.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a graph showing the relationship between the amount of exposure by a safelight used in one embodiment of the present invention and the amount of correction of the line width of the circuit, and the horizontal axis is the illuminance I (Lux) of the safelight.
Exposure amount expressed as a logarithm of the product of and exposure time t (min),
The vertical axis is the amount of line width correction. Also, curves A, B, C,
D has safelight illuminance of 0.3, 0.8, and 1, respectively.
The case of 0.40 is shown.

Figure 2 is a graph showing the relationship between safelight illuminance and exposure time when the line width correction amount is 10 μm, where the horizontal axis is the logarithm of the safelight illuminance factor (L u The axis is the exposure time by safelight.

Usually, unexposed film for drawing is a darkroom type, so a red light is used as a safe light.

Exposure by safelight has very poor exposure efficiency because it uses a wavelength outside the chromatic sensitivity of the unexposed film, but development nuclei are generated on the surface of the film emulsion by exposure. Further, in the field of precision photography, mask films are developed using a chemical developer that develops from the emulsion surface of the film.

Therefore, even when exposed to light using safelight, a blackened density can be produced in the development process. Therefore, we varied the distance between the safelight and the unexposed film emulsion surface, varied the illuminance on the film emulsion surface to 0.3°, 0.8 lux, and 10.40 lux, and changed the exposure time for each illuminance. When an image is created and developed using an image creator after the exposure amount is applied, the behavior shown in FIG. 1 is exhibited. For example, in the case of curve C, when the exposure amount (1ogIt) is 3.0, it is possible to correct a line width of 20 μm, and when the exposure amount is 3.3, it is possible to correct a line width of 50 μm.

In addition, as shown in Figure 1, even in safelight exposure, reciprocity law failure agents (normally, at the same exposure amount,
The exact same result can be obtained, so if the illumination intensity increases by 10 times, the exposure time can be reduced to 1/10, but when the light is strong or weak, the effectiveness of the light is less, so the exposure time should be longer than the equivalent time under normal conditions. Therefore, even if the exposure amount is the same, the exposure time to obtain the same line width correction amount changes due to the difference in illuminance. As an example, when the lie width correction amount is 10 μm, the illuminance (1ogI) is -0, as shown in FIG.

1, an exposure time of 96 minutes is required, but the illuminance is 1.
In the case of 6, correction can be performed with an exposure time of 36 minutes.

Next, a case where two types of mask films having the same circuit pattern but different line widths, for example, line widths of 100 μm and 110 μm, are formed will be described.

First, a mask film having a line width of 100 .mu.m is formed by exposing an unexposed film to a predetermined amount of light to obtain a line width of 100 .mu.m using a drawing machine, and then developing it, as in the conventional method.

Next, to form a mask film having a line width of 110 μm, the safelight exposure conditions for which the line width correction amount is 10 μm are determined according to FIG. 1 or FIG. 2, and the unexposed film is exposed under these conditions. Next, the film is exposed to light using a drawing machine under the same conditions as for forming the mask film having a line width of 100 μm, and then developed. By this operation, a mask film having a circuit pattern with a line width of 110 μm can be easily obtained.

〔Effect of the invention〕

As explained above, the present invention has the following effects by exposing an unexposed film to light using a safelight, then performing a predetermined exposure using a drawing machine and developing it to form a mask film.

(1) Since the same film as normal drawing film can be used, development processing can be unified, and operation and management can be made very simple.

2) Since the line width can be corrected under the same drawing conditions, there is no need for complicated light amount adjustment of the drawing machine.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing the relationship between the exposure amount of the safelight used in one embodiment of the present invention and the line width correction amount, and the relationship between the illumination intensity and exposure time to obtain a correction amount of 10 μm. This is a graph showing.

Claims (1)

[Claims] A mask film characterized in that an unexposed film is exposed to a predetermined amount using a safelight having a wavelength outside the chromatic sensitivity on the spectral sensitivity curve of the film, and then a predetermined exposure is performed using an image forming machine for development processing. Formation method.