JPS6151150A - Formation of pattern and exposing device - Google Patents

Abstract

PURPOSE:To obtain a resist image of high resolution at a high speed by carrying out primary exposure and secondary exposure in an atmosphere of necessary gas and forming a pattern latent image. CONSTITUTION:The space 6 between an exposure mask 3 and photosensitive resist 2 on a printed board 1 is put in a nonactive atmosphere of nitrogen gas, etc., and the primary exposure using parallel energy rays such as ultraviolet rays is carried out to set only the surface part of the resist 2 in conformity with the pattern of the mask 3. Then, the secondary exposure using parallel rays is performed while the space 6 is placed in an active gas atmosphere of oxygen gas, etc., to set up to the bottom part of the resist 2. In this case, even if scattered or reflected light strikes the surface of the resist 2 where light should not hit, its setting is hardly caused because of an oxygen impediment. Thus, a resist image is formed at a high speed by the primary exposure and to high resolution by the secondary exposure.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention involves exposing a photosensitive resist of a printed circuit board coated with a photosensitive resist to light through an exposure mask,
The present invention relates to a flat turn forming method for obtaining a predetermined pattern latent image on a printed circuit board, and an exposure apparatus for implementing the method in close contact with a VCM.

[Conventional technology]

Conventionally, it has been known to shorten the exposure time by performing ultraviolet exposure for curing a photosensitive resist in a nitrogen gas atmosphere. That is, in FIG. 8, (1) is a printed circuit board, (2) is a photosensitive resist, (3) is a dark exposure mask having a turn to be formed on the photosensitive resist (2), ( 3a) u This is the dark side. (4) is a table, (5) is an airtight seal, and a printed circuit board (
1) is surrounded by a space (6) that can be kept airtight. In addition, (force is the inlet of nitrogen gas (N2), (8) is the outlet of nitrogen gas, and the space (6) is filled with nitrogen gas. In this state, the photosensitive resist of the printed circuit board (1) (2) The upper surface is exposed to ultraviolet parallel energy beams (9) through an exposure mask (3), and a predetermined pattern latent image is obtained on the printed circuit board (1).

[Problem that the invention seeks to solve]

This conventional method is effective when the photosensitive resist (2) is thin. However, in order to form, for example, a solder resist that requires a thick film, photosensitive resist (
The film thickness of No. 21 is about 20 μm to 100 μm, and it is coated with nitrogen,
If it is cured to the bottom in an elementary gas atmosphere, the curing of the surface part will not be affected by oxygen inhibition at all, so the curing will progress abnormally and the image will be larger than the opening of the exposure mask (3). There was a problem that a resist image with high resolution could not be obtained because of the formation of a resist image. For example, the 9th
The figure is the current image) After the image, 7),, 51 images. Also shows the condition schematically. A. The surface portion of the photosensitive resist (2) is shown to be more hardened than necessary.

In view of this, the present invention provides a method for forming holes and turns for obtaining a high-resolution resist image, and its implementation, while taking advantage of the fact that the light time can be greatly shortened by exposure in a nitrogen atmosphere, for example. This provides an exposure device that can be used directly.

[Means for solving problems]

In order to solve the above problems, the first FfJ/”tar/
The formation method is as shown in FIG. 1A, using a photosensitive resist (
2) It has the steps of primary exposure in which the upper surface is exposed to light in an inert gas (for example, nitrogen gas) atmosphere, and secondary exposure in which the upper surface is exposed to light in an active gas (for example, air) atmosphere, as shown in FIG.

Further, in the exposure apparatus of the second invention, the exposure mask (3) is arranged parallel to the printed circuit board (1) with a predetermined uniform gap, and the periphery of the printed circuit board (1) is provided with a space that can be kept airtight. (6), and for this space (6),
Three-way valve αη that switches between filling inactive gas and active gas
This is achieved by providing the following measures.

[Effect]

In the first invention pattern forming method, first, FIG.
As shown in the diagonally shaded diagram, only the surface portion of the /11 resist (2) is hardened in the primary exposure step. And then the same figure B
As shown by diagonal lines in , the photosensitive resist (21) is hardened to the bottom in the secondary exposure step.

In this case, even if the light on the surface of the photosensitive resist (2) is not to be reflected, scattered light or reflected light will be inhibited by oxygen, so t! Hardly hardens. Therefore, the exposure time can be shortened in the -missing exposure step, and a high-resolution resist image can be obtained because of the presence of the secondary exposure step.

Further, in the second invention exposure apparatus, a printed circuit board (
The space around (1) (6) Ic can be selectively filled with an inert gas and an active gas, and the steps of primary exposure in an inert gas atmosphere and secondary exposure in an active gas atmosphere can be performed; It can be directly used to implement the first invention pattern forming method described above.

[Below the royalty fee, with reference to Figures 2 and 3,
Let me explain about the royalty fee for the invention. In these FIGS. 2 and 3, parts corresponding to those in FIG. 8 are designated by the same reference numerals.

In the same figure, aα is a base, and on this base αα
and an X-Y table t1υ whose position can be arbitrarily changed in the Y direction. A printed circuit board (1) covered with a photosensitive resist (2) is placed on this X-Y table αυ.

In addition, (3) is an exposure mask and a photosensitive resist (
2) It has a pattern to be formed thereon.

This exposure mask (3) is held by a mask holder α2 and arranged parallel to the printed circuit board (1) K with a predetermined uniform gap, for example, 0.011111 to 10 mm.

In this case, the mask holder u7J is connected to a hydraulic cylinder (13) fixed to the base (101, and this hydraulic cylinder (131 controls the height position of the exposure mask (3).
) can be changed.

Further, in this example, the exposure mask (3) is made of Nonoirex glass (registered trademark) or quartz glass. For example, the transmission properties of the new Irx glass are 4th
It is represented as shown in the figure. Further, the energy distribution of, for example, a high-pressure mercury rung used as a light source is expressed as shown in FIG.

By using Pyrex glass, the wavelength of 300 nm to 400 nm, which is an active ingredient, can be utilized.
Compared to using polyester film or general glass, this method has the advantage of requiring only the exposure time of a fishing machine.

Returning to Figures 2 and 3, I is a voltage-tight seal, which is placed on a KX-Y table (lυ) to surround the periphery of the printed circuit board (1). is a space (6) that can be kept airtight.

In addition, (151 is a nitrogen gas supply path, (1G is an air supply path, and 1G is an electromagnetic pulp for switching between nitrogen gas and air. X-Y table (l
The air is blown out through the air outlet α9 into the space (6) through the gap υ. In addition, ■ is a nitrogen gas or air outlet formed on the X-Y table (lυ). The electromagnetic pulp @ is supplied to the discharge pump via the discharge channel Qυ. In this case, the electromagnetic pulp @ is opened only during discharge.

Further, (9) is made to be able to irradiate and expose the photosensitive resist (2) with a parallel energy beam of ultraviolet light through an exposure mask (3).

In the above apparatus, exposure is performed in the following steps.

First, X-Y Chi Lumi υ K, photosensitive resist (2)
The printed circuit board (1) coated with is set and aligned with the exposure mask (3) in the X-Y direction, and the height position of the exposure mask (3) is adjusted.

Next, by switching the electromagnetic pulp type, nitrogen gas is blown into the space (6) through the blow-off port α9. In this case, the electromagnetic pulp is first opened and the air in the space (6) is discharged,
When the space (6) is filled with nitrogen gas, it is closed.

Next K, in a state where the space (6) is filled with nitrogen gas, that is, in a nitrogen gas atmosphere, the parallel energy beam (9)
is irradiated onto the photosensitive resist (2) through the exposure mask (3) and 1. - Missing exposure. , in this case, Figure 1A
As shown in K, only 5 minutes of the surface of the photosensitive resist (2) is cured.

next,! By switching the magnetic pulp αη, air is blown into the space (6) through the air outlet a9. In this case, the electromagnetic pulp @ is first opened, the nitrogen gas in the space (6) is exhausted, and the space (6) is filled with air and then closed.

Next, the space (6) is filled with air, that is,
In an air atmosphere, a parallel energy beam (9) is irradiated onto the photosensitive resist (2) through an exposure mask (3) for secondary exposure. In this case, as shown in FIG. 1B, the photosensitive resist (2) is hardened to the bottom. In this case, even if scattered light or reflected light hits areas on the surface of the photosensitive resist (2) that should not be exposed to light, they are hardly cured due to oxygen inhibition.

Exposure is performed as described above, and a predetermined pattern latent image is obtained on the printed circuit board (1).

Incidentally, FIG. 6 shows the amount of deviation α from the ideal as shown in FIG. 7 after actual exposure and development. In this case, the width of the dark part (3a) of the exposure mask (3) is 240 μm.
, the thickness of the photosensitive resist (2) is 35 to 40 μm, and the parallel energy light # (9) is 1 mw.

In FIG. 6, rOJ has α less than ±ioAm,
“Δ” means α is ±10 to 20 μm, and “×” means ±20 μm or more. Furthermore, ``CuJ'' is data on the circuit/arm turn, and ``Group'' is data on other substrates.

Moreover, "-" indicates negative, and the others indicate positive. still,
When the primary exposure in a nitrogen gas atmosphere was for 2 seconds, it was not cured. In FIG. 6, the area within the thick black line frame is effective in terms of resolution.

Note that the nitrogen gas in the above embodiments may be one that does not contain oxygen, such as carbon dioxide gas, and the air in the above embodiments may be oxygen. Further, it goes without saying that the means for selectively filling active gas and inactive gas is not limited to the above embodiment.

〔Effect of the invention〕

As described above, according to the first invention pattern forming method, the photosensitive resist is coated with an inert gas (for example, nitrogen gas).
It has the steps of primary exposure in an atmosphere and secondary exposure in an active gas (e.g. air) atmosphere. Since there is an exposure step, a high-resolution resist image can be obtained. For example, in conventional exposure only in a nitrogen atmosphere, the photosensitive resist is 35 to 40p
m film thickness, 0.5 jL1 pattern/0.511
The hardness of the base was the limit, but in the method of the present invention, Q
, lxm pattern/0.1 dragon sweep is possible.

According to the exposure apparatus of the second invention, if the exposure mask is arranged parallel to the printed circuit board with a uniform predetermined gap, and the space around the printed circuit board is made airtight, coprecipitation occurs. This device is equipped with a means for selectively filling an inert gas and an active gas in the inert gas atmosphere, and can carry out the steps of primary exposure in an inert gas atmosphere and secondary exposure in an active gas atmosphere. , can be directly used to implement the above-mentioned first invention pattern forming method. Moreover,
Since the volume of the space is small, there is an advantage that gas switching and filling can be carried out efficiently.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the first invention pattern forming method, FIGS. 2 and 3 are configuration diagrams showing embodiments of the first and second inventions, respectively, and FIGS. 4 to 7 are diagrams for explaining the pattern forming method of the first invention. FIG. 8 is a configuration diagram showing the prior art, and FIG. 9 is a diagram for explaining the same. (1) is a printed circuit board, (2) is a photosensitive resist, (3
) is the exposure mask, (3a) is the dark area, (6) is the space, (
9) is a parallel energy ray, an and (23 are electromagnetic valves, respectively.) Hidemori Matsukuma...':15,' Figure 4 Figure 5 → Command t (nm) Figure 6, Figure 7

Claims (1)

[Claims] 1. A printed circuit board at least partially covered with a photosensitive resist and an exposure mask having a pattern to be formed on the photosensitive resist are held in parallel with a uniform predetermined gap. , a pattern forming method in which the photosensitive resist is irradiated and exposed with parallel energy beams through the exposure mask to form a predetermined latent pattern image on the printed circuit board, wherein the exposure is performed without exposing the photosensitive resist to A pattern forming method comprising: primary exposure in an active gas atmosphere; and secondary exposure in an active gas atmosphere. 2. An exposure apparatus comprising a printed circuit board at least partially covered with a photosensitive resist, and a photographic means such as a light source for pattern formation and an exposure mask arranged on the photosensitive resist. A means for arranging a mask parallel to the printed circuit board with a uniform predetermined gap, creating a space around the printed circuit board that can be kept airtight, and selectively filling this space with an inert gas and an active gas. An exposure apparatus characterized by being provided with.