JPH04367215A - Formation method for thick-film pattern - Google Patents

Abstract

PURPOSE:To provide a method wherein the deformation such as the slack or the like of a protruding pattern is not caused and a protruding part whose aspect ratio is high is formed on a substrate with high accuracy. CONSTITUTION:The formation method of a thick-film pattern is composed of the steps of forming a positive-type photosensitive layer 2 on a substrate 1; forming a mask pattern 7 on the surface of the photosensitive layer 2; spraying a developer to remove the inessential photosensitive layer while irradiating the substrate 1 with ultraviolet rays; baking and fixing a filler 10 filled into the removed part; and removing the filler 10.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to fluorescent display tubes, PDPs,
The present invention relates to a method for forming a thick film pattern on a substrate used in a display device such as a display using an FE cathode. In particular, this method relates to a method for forming a convex thick film pattern with a large aspect ratio on the surface of a substrate.

0002

[Prior Art] Generally, in a fluorescent display tube, electrons emitted from a cathode fly through a vacuum and strike an anode coated with a phosphor, causing a current to flow through the anode, causing the phosphor coated on the anode to emit light. ing. Therefore, since it is based on the same principle as a vacuum tube, the inside of the envelope is in a high vacuum state, and atmospheric pressure is applied to the envelope from the outside. This force of atmospheric pressure increases as the degree of vacuum within the envelope increases and as the area of the envelope increases. Therefore, the glass plate of the envelope must be sufficiently thick so that the envelope will not be deformed or destroyed by the force of this atmospheric pressure. However, if the glass plate is made thicker, the envelope becomes heavier, so in order to achieve strength and weight reduction at the same time, a reinforcing material such as a rib is added between the base plate of the envelope and the front plate facing the base plate. A structure is known in which the external pressure is supported. By providing a stand or the like in this manner, even a thin glass plate can be used as the substrate or front plate of the envelope.

[0003] In order to form the above-mentioned protrusions, it is necessary to form convex portions on the glass substrate. As an example of a method for forming this convex portion with high precision, a method using a screen printing method is known. First, a paste is formed by mixing the main component, low-melting glass powder, in a vehicle, and this paste is printed on a glass substrate using a screen printing method. Since printing can be performed to a thickness of about 10 to 50 μm in one printing, a convex pattern with a thickness of about 200 to 350 μm can be formed on the substrate by drying this and repeating further printing. and,
This substrate is fired all at once to form a predetermined convex structure.

Next, there is a photosensitive paste method as another method for forming convex structures. In this method, first, a photosensitive paste containing a low-melting point glass powder and a negative photosensitive vehicle is applied all over a glass substrate, and a mask is placed above the substrate and exposed to ultraviolet light through this mask. After this is developed, it is fired to form convex portions in a predetermined pattern.

[0005]

SUMMARY OF THE INVENTION The conventional forming method described above has the following problems. (2) According to the first screen printing method, there was a positional shift in the formed pattern, the in-plane uniformity and printing accuracy were not very high, and it was difficult to form a fine convex pattern. Furthermore, during firing, the low melting point glass powder flows and deforms the pattern (referred to as sag), making it difficult to form high convex portions. Furthermore, there is a problem in that a filler is mixed in to prevent sag, and a large amount of gas is released. ■According to the second photosensitive paste method, there is a problem that it is difficult to obtain a large film thickness due to scattering and absorption of light by particles in the paste. /base length) is difficult to form with high precision using a thick film.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming convex portions having a large aspect ratio on a glass substrate with high precision without deforming the pattern.

[0007]

[Means for Solving the Problems] According to the method for forming a thick film pattern as set forth in claim 1, the steps include: forming a photosensitive layer by coating a positive type photosensitive paste on a substrate; A step of directly patterning a thin film on the surface to form a mask, a step of spraying a developing solution while exposing ultraviolet rays through the patterned mask to remove the photosensitive layer in the exposed area, and a step of removing the photosensitive layer in the exposed area. The method includes a step of filling with a filler, drying and firing, and a step of removing the filler.

Further, in the method for forming a thick film pattern, a pigment that easily absorbs ultraviolet light may be mixed into the positive type photosensitive paste.

Furthermore, in the thick film pattern forming method, the mask may form a metal thin film by means of photolithography.

0010

[Operation] A positive type photosensitive paste is applied onto the substrate, and when it is exposed to ultraviolet rays, the portions exposed to ultraviolet rays can be removed by a developer. Therefore, by spraying a developer while exposing the layer to ultraviolet light, the exposed portion of the thick photosensitive layer can be easily removed down to the bottom.

[0011]

[Embodiment] A first embodiment of the present invention will be explained with reference to FIG. As shown in FIG. 1(a), a positive type photosensitive paste is applied to the upper surface of the substrate 1 by a doctor blast method,
The photosensitive layer 2 is formed by drying at 80° C. for 30 minutes. The coating thickness of the photosensitive paste varies depending on the height of the convex portion of the thick film pattern to be finally formed, but the coating thickness takes into account the amount that will be reduced in the final baking process. In this example, the final number is 200.
Since a convex portion of 4 μm is formed, the photosensitive paste
It was applied to a thickness of 50 μm. The substrate 1 is made of a heat-resistant and insulating material such as a glass plate, a ceramic plate, or a silicon plate.

The positive type photosensitive paste 2 contains approximately 75% low melting point frit glass with an average particle size of 3 μm;
It contains 5% of a black pigment with an average particle size of 1 μm, and the remainder contains a positive photosensitive vehicle that reacts when irradiated with ultraviolet rays and can be removed by a developer. Other fillers may be mixed, or metal powder or the like may be mixed if conductivity is desired.

[0013] An example of the positive photosensitive vehicle is one comprising a phenol novolak resin, naphthoquinone diazide as a photosensitizer, and an organic solvent.

Next, as shown in FIG. 1B, a thin aluminum film 3 having a thickness of 0.3 μm is formed on the upper surface of the photosensitive layer 2 by sputtering. The film thickness may be other than the above thickness as long as it can block ultraviolet rays.

Furthermore, as shown in FIG. 1(c), a photoresist 4 is applied to the upper surface of the aluminum thin film 3, exposed to ultraviolet light through a predetermined pattern 5 of the convex portions, and the exposed portion is removed with a developer. Figure 1
A mask pattern 7 as shown in (d) is formed.

Next, as shown in FIG. 1(e), the substrate 1 on which the mask pattern 7 is formed is irradiated with ultraviolet rays 6 from above the mask pattern 7, and a developer for the photosensitive layer 2 is applied. A 0.5% aqueous solution of caustic soda was added to the photosensitive layer 2.
Develop by spraying on. Since the photosensitive layer 2 contains a positive photosensitive vehicle, the portions irradiated with ultraviolet light are removed by a developer.

The ultraviolet ray 6 is preferably a parallel light source. A parallel light source can be achieved by using a slit in front of the light source and moving the substrate 1 side. Further, the intensity of the parallel light source is, for example, 10 mw/cm 2 for exposure.

As shown in FIG. 1(f), the recessed portion of the photosensitive layer 2 is filled with a filler 10. Then, as shown in FIG. The filler 10 may be any material that does not soften at a temperature of 400 to 600°C, for example, a water-soluble inorganic solid powder such as sodium chloride, potassium sulfate, etc. (with an average particle size of 1
60% of μm), 4% of organic solvent such as methyl ethyl ketone
It consists of 0%.

The filler 10 is applied to the recesses on the thick film pattern 11 using a doctor blade method, dried at 80° C. for 30 minutes, and then fired in a firing furnace in an oxidizing atmosphere with a peak temperature of 550° C.

In the firing process, the low melting point frit glass constituting the thick film pattern 11 is softened and becomes an integral glass shape, and the organic components contained in the filler 10 and the thick film pattern 11 are softened. decomposes and evaporates. The thick film pattern 11 softens, but the filler 10 existing around the thick film pattern 11 acts to support the shape of the thick film pattern 11, so the shape of the thick film pattern 11 is deformed during the firing process. Never. Therefore, after baking, the substrate 1
When cooled, the thick film pattern 11 made of low melting point frit glass is fixed in a highly accurate shape according to the pattern of the photomask 5.

[0021] Then, the cooled substrate 1 is spray-cleaned with water to remove the filler material 10. As a result, as shown in FIG. 1(h), a high-precision thick film pattern 11 that does not deform even after the firing process is created; for example, one side of the convex portion has a length of 50 μm and a height of 200 μm; Therefore, a pattern with an aspect ratio of 4 is formed on the substrate 1.

Next, a second embodiment of the present invention will be explained using FIG. 2. A substrate 1, a photosensitive layer 2, an aluminum thin film layer 3,
A photoresist layer 4 is laminated and exposed through a mask 5.
The steps shown in FIGS. 1(a) to 1(d) until developing and forming the mask pattern 7 on the photosensitive layer 2 are as follows:
Since this is the same as the first embodiment, the explanation will be omitted.

After the step of forming the mask pattern 7 shown in FIG. 1(d), while exposing the photosensitive layer 2 to ultraviolet light 6,
There is a developing step in which a developer 8 is sprayed. In the second embodiment, as shown in FIG. 2, this developing step is performed by standing the substrate 1 vertically and installing an ultraviolet light source to expose the ultraviolet rays 6 from the lateral direction. A nozzle 12 that injects the developer 8 is installed so as to be able to scan in the direction of the arrow. Development is carried out by spraying a developer (0.5% caustic soda aqueous solution) while being exposed to ultraviolet rays 6, and the portion exposed to ultraviolet rays 6 is removed, leaving the photosensitive layer 2 under the mask pattern 7. A photosensitive layer pattern 9 as shown in 1(e) is formed. Figure 1 (f
) to (h), the process of filling and firing the filler 10 and the process of removing the filler with water after firing are the same as in the first embodiment, so their explanation will be omitted. By performing the development process while exposing the substrate 1 to ultraviolet rays 6 while standing vertically in this way, the photosensitive layer removed by development can easily flow out together with the developer, and the development time can be shortened.

When the thick film pattern 11 of the embodiment described above is used as an envelope of a display device such as a fluorescent display tube,
A thick film pattern 11 is formed on the substrate 1 and the front plate facing the substrate (
(not shown), it can be used as a reinforcing member to support the atmospheric pressure applied to the envelope.

The convex thick film pattern formed by the method of the present invention is not only used as a reinforcing member for the envelope of the above-mentioned fluorescent display tube. In addition, it can be used to form three-dimensional structural members such as the base of a planar grid provided adjacent to an anode or an electrode structure in which a field emission device is used as a cathode. Furthermore, although a water-soluble substance was used as the filler in this example, an insoluble filler may also be used. In that case, the filler may be removed by a physical method such as spraying with pressurized water. can.

[0026]

[Effects of the Invention] ■ A photosensitive layer was formed using a positive type photosensitive paste, and a mask pattern was directly formed on the surface of the photosensitive layer. Therefore, since there is no need to provide an exposure mask separate from the substrate, development can be performed while exposing to ultraviolet light, compared to conventional methods in which the exposure and development steps are separate.
This has the effect that a process can be omitted.

(2) Even if the photosensitive layer is thick, since development is performed while exposing to ultraviolet rays, a precise pattern can be easily formed.

■Since the photosensitive paste contains a light absorbing agent, ultraviolet rays are absorbed and almost no ultraviolet rays are scattered, and the unexposed areas are protected and high-quality. A thick film pattern with a high aspect ratio can be obtained with high precision.

(2) It could not be formed using conventional methods. This has the effect of forming a thick film pattern having a film thickness of several 100 μm and having convex portions with an aspect ratio of 1 or more.

[Brief explanation of the drawing]

[Figure 1] (a) (b) (c) (d) (e) (f) (g)
(h) It is a process diagram of the first embodiment of the present invention.

FIG. 2 is a schematic diagram of a developing process according to a second embodiment of the present invention.

[Explanation of symbols]

Claims (3)

[Claims] 1. A step of forming a photosensitive layer by coating a positive type photosensitive paste on a substrate, a step of directly patterning a light-shielding thin film on the surface of the photosensitive layer to form a mask pattern, and a step of forming a mask pattern by directly patterning a light-shielding thin film on the surface of the photosensitive layer. a step of spraying a developing solution while exposing to ultraviolet light through the mask pattern to remove the exposed portion of the photosensitive layer; a step of filling the portion from which the photosensitive layer has been removed with a filler material, drying and baking it; and a step of drying and baking the filler material. A method for forming a thick film pattern, comprising the step of removing. 2. The method for forming a thick film pattern according to claim 1, wherein the positive type photosensitive paste contains a pigment that easily absorbs ultraviolet light. 3. The method of forming a thick film pattern according to claim 1, wherein the mask pattern is a metal thin film patterned by photolithography.