JPH09262603A - Metallic sheet for shadow mask and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the grade of a color display tube and to reduce the manufacturing cost by adopting the metallic sheet for shadow masks whose surface roughness is 0.2-1.5μm Ra, 0.5-2.0 Rsk, 50-200μm Sm. SOLUTION: With working rolls having the roughness which satisfies the undermentioned conditions, i.e. Ra is 0.5-2.0μm, Rsk is 0-(-2.0), Sm is 50-200μm in the surface, the finish rolling is executed at the draft of >=5% per pass one or more times and the surface roughness of the metallic sheet for shadow mask which satisfies Ra of 0.2-1.5μm, Rsk of 0.5-2.0 and Sm of 50-200μm is manufactured. When the finish rolling for raggedness of this base stock 1 for shadow mask is executed with the working rolls, air between the base stock 1 for shadow mask and a pattern 3 is sucked, so both are in close contact. In this way, the reflected light at the time of exposure becomes uniform, the accuracy of pattern is improved and the manufacturing cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal plate for a shadow mask used as a cathode ray tube for a color television and the like, and a method for manufacturing the same, and more particularly to a metal plate having not only a small average surface roughness but also a dense surface structure. The present invention relates to a technology for producing a high-quality thin Fe-Ni alloy sheet for shadow masks. In particular, the present invention is a Fe-Ni for a shadow mask which is excellent in etching piercing property, has no unevenness in the amount of transmitted light in an etching flat mask after piercing, and has very little image unevenness (mottling) when incorporated in a display picture tube. We propose alloy sheet.

[0002]

2. Description of the Related Art In recent years, the quality of display picture tubes for televisions has been improved and the demand for preventing color shift has increased. Recently, to meet this demand, low thermal expansion Fe-
Ni alloy thin plates are drawing attention. Usually, this Fe-Ni alloy thin plate is a hot-rolled steel sheet that is subjected to appropriate strain relief annealing in a continuous annealing furnace or a batch annealing furnace, and after that, if necessary, it is subjected to flaw removal and then cold finishing. It is manufactured through the steps of rolling and temper rolling (including dull rolling). Fe-for shadow mask manufactured in this way
For the Ni alloy thin plate, it is important to control the roughness of the plate surface after the temper rolling. The reason is that the roughness of the plate surface determines the quality characteristics of the color display tube, as will be described later.

Generally, regarding the surface roughness display of a metal plate or the like, the size of the roughness represented by the roughness parameter such as Ra, Rz or Rmax and the unevenness (mountain valley) represented by the Sm, Rsk, Rθa or the like. The cross-sectional shapes of, and are all representative indexes for roughness display.

The surface roughness of such a metal plate is a characteristic that greatly affects the uniformity of patterning during photoetching and the uniformity of the opening shape during etching perforation in the shadow mask material manufacturing process. In addition, it is an important factor that determines the clarity of an image on a color display tube and the quality of unevenness called mottling.

Conventionally, such a shadow mask is manufactured through the following steps. First, the metal plate (Fe
-Ni metal plate) is pretreated by degreasing, etc., and then coated with resist on both sides, and the pattern is placed on it. At this time, vacuuming is performed in order to improve the adhesion between the pattern and the material. Then, when the contact between the metal plate and the pattern is obtained, exposure is performed from both sides with an ultra-high pressure mercury lamp to print the pattern on the resist on the surface of the metal plate. After that, development is performed, and a non-exposed portion of the photoresist is removed through a water washing step, and the exposed portion is stabilized by a film hardening process and a baking process to obtain an acid resistant film. Then, it is sent to an etching step, and the unexposed portion is perforated with a ferric chloride solution to obtain a flat mask. Further, since this flat mask needs to be pressed to have a spherical shape corresponding to a cathode ray tube, it is annealed in an HX gas atmosphere before that. The obtained annealed material is passed through a leveler to prevent stretcher strain, and then press-formed (in the case of Fe-Ni alloy thin plate as it is), to obtain a spherical surface or an aspherical surface. Then, finally, in order to prevent doming due to localized heat buildup and to prevent electron beam scattering, a shadow mask is formed by performing a blackening treatment in which an oxide film is attached to the surface in a CO / CO ₂ atmosphere.

[0006]

FIG. 1 is a schematic view of a photo-etching step in manufacturing a shadow mask, and shows a process of adhering a shadow mask material 1 and a pattern 3 to each other. Between the shadow mask material 1 and the pattern 3, there is a resist film 2 having irregularities of the shadow mask material. As is clear from this figure, air between the shadow mask material 1 and the pattern 3 is sucked and exhausted by the vacuum pump to bring them into close contact with each other. At this time, it is desirable that the air remaining between the two is quickly and uniformly exhausted without staying. However, the conventional shadow mask material has a problem that since the surface roughness is appropriate, nonuniform adhesion occurs due to the retention of air, and patterning is not performed faithfully during exposure.

FIG. 2 is a diagram showing a pattern of the shadow mask material 1 during exposure. Generally, there are two types of light rays passing through the pattern 3, one of which is absorbed by the resist 2 and the other of which is reflected by the surface of the material and absorbed again in the resist 2. The latter (reflection absorption) is strongly influenced by the roughness of the material surface, and if the degree of this roughness or the pattern is not appropriate, it becomes scattered light, disturbing the contour shape of the pattern and making the hole shape jagged, or the pattern hole It may worsen the roundness. On the other hand, in many cases, conventional shadow mask materials tend to generate scattered light and have uneven hole shapes because the surface roughness is inadequate in many cases.

An object of the present invention is to provide a material for a shadow mask having a suitable surface roughness, thereby improving the pattern accuracy and realizing a high quality color display tube. Another object of the present invention is to propose a technique for advantageously manufacturing such a metal plate for a shadow mask.

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems of the prior art, the inventors
(Metal plate for shadow mask) We have conducted an earnest research on roughness. As a result, regarding the surface properties (roughness) of the metal plate, the center line average roughness (Ra), the relativity (Rsk) and the average mountain interval (S
It was concluded that the surface roughness indicated by the three roughness indications in m) should be suitable. In other words, if a suitable metal plate surface shape (roughness) determined by such roughness display is used,
In addition, it is possible to improve the exhaust performance during evacuation,
As a result, the adhesion between the material and the resist is enhanced, and thereby the reflected light at the time of exposure becomes uniform, the pattern accuracy is improved, and the contour shape of the etching perforation is effective.

According to the present invention, as a method for providing such surface texture, first, a roll rolling process is performed by a processing roll that has been subjected to a predetermined grinder polishing, and then a predetermined finish rolling is performed. Have found that a metal plate for a shadow mask having the above desired surface roughness can be obtained.

That is, the present invention is characterized in that (1) the surface roughness is a metal plate satisfying the following conditions; Ra: 0.2 to 1.5 μm Rsk: 0.5 to 2.0 Sm: 50 to 200 μm. Metal plate for shadow mask. In the present invention, the metal plate is C:
0.02 wt% or less, Mn: 0.5 wt% or less, Si: 0.2 wt% or less,
Cr: 0.5 wt% or less, Ni: 30 to 45 wt%, P: 0.01 wt% or less, S: 0.01 wt% or less, Al: 0.1 wt% or less, and a composition having the balance Fe and unavoidable impurities is preferable.

(2) According to the present invention, the metal plate is a processing roll whose surface has a roughness satisfying the following conditions; Ra: 0.5 to 2.0 μm Rsk: 0 to −2.0 Sm: 50 to 200 μm. The surface roughness is Ra: 0.2 to 1.5 μm, R by finish rolling at least once at a rolling reduction of 5% or more per pass.
sk: 0.5 to 2.0 and Sm: 50 to 200 μm, a method for producing a metal plate for a shadow mask, which is characterized by producing a metal plate having an uneven surface, and a finish cold rolling step. Ra: 1.0-3.0 μm, Rt: 6
Rolls that have been grinder polished with a surface roughness of ~ 30μm are subjected to roll rolling treatment from 1000 to 10000 times, and the surface obtained is Ra: 0.5 ~ 2.0 μm, Rsk: 0 ~ -2.0.
, Sm: 50-200 μm, surface hardness Hv is 800 or more, and finish rolling is performed at a reduction rate of at least 5 to 20% per pass.
a: 0.2 to 1.5 μm, Rsk: 0.5 to 2.0 and Sm: 50 to 2
This is a method of manufacturing a metal plate for a shadow mask that satisfies 00 μm.

In the present invention, as an example of the metal plate, C: 0.02 wt% or less, Mn: 0.5 wt% or less, Si: 0.
2 wt% or less, Cr: 0.5 wt% or less, Ni: 30 to 45 wt%, P:
0.01 wt% or less, S: 0.01 wt% or less, Al: 0.1 wt% or less,
It is preferable to use a metal plate having a composition consisting of the balance Fe and unavoidable impurities.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As a method for adjusting the surface of a metal plate for a shadow mask, conventionally, the surface of a rolled metal plate is
Processing was performed by shot blasting, liquid honing, etc., and then rolling was performed under relatively low pressure. However, in the above shot blasting, there is a problem that unevenness of roughness is caused due to variations in the projection energy of the steel grit, especially waviness locally occurs, and the roundness of the hole shape after etching becomes poor. Further, during rolling, a slight waviness causes a change in the frictional force between the roll and the metal plate, and as a result, striped gloss unevenness occurs on the surface of the metal plate.

On the other hand, in liquid honing, the above-mentioned waviness does not occur, but since the steepness of roughness is high, scattered light increases during pattern exposure, the contour shape becomes jagged, and uneven quality deteriorates. There was a problem.

Further, the processing rolls used under the prior art are those in which the surface is merely mechanically roughened to form irregularities, and the coefficient of friction with the surface of the metal plate is large and there are many restrictions on rolling conditions. In addition to the problem, the roll surface is heavily worn and the surface roughness is different between the early rolling and the latter rolling.

A feature of the present invention is that the surface of the metal plate (material) has a surface roughness suitable as a material for a shadow mask. As a result, it is possible to improve the exhaust performance during evacuation in the photoetching process, to make the reflected light during exposure uniform for patterning, and to make the contour shape clear during etching perforation. It is possible to improve the quality unevenness (mottling) of the color display tube.

Another feature of the present invention is that the roll surface is subjected to a predetermined grinder polishing process and then roll-rolled to provide a work-hardened layer on the surface to improve wear characteristics. Especially.

In the present invention, in order to obtain a predetermined surface shape (roughness), first, as a treatment in the cold rolling step,
Ra (centerline average roughness) after grinder polishing: 1.0
~ 3.0 μm, Rt (maximum height): Roll having a surface roughness of 6 to 30 μm was subjected to roll rolling treatment 1000 to 10000 times, and the surface roughness of the roll after this roll rolling treatment was R
a: 0.5 to 2.0 μm, Rsk (relative value): 0 to −2.0, Sm
(Average mountain interval): 50 to 200 μm, work roll having a surface hardness Hv of 800 or more, a rolling reduction of 5% or more, preferably
By finishing cold rolling of 5 to 20%, the surface roughness Ra: 0.2 to 1.5 μm, Rsk: 0.5 to 2.0, Sm: 50 to 200
It is possible to manufacture a metal plate for a shadow mask having a thickness of μm.

In the present invention, the rolling treatment by the rolling rolls means that the rolling rolls are brought into contact with each other at a contact pressure of 5 to 20 kg.
the method comprising rotating in contact with each other at f / mm ^2, the roll surface of a work roll used in the rolling process Ra: 1.0
~ 3.0 μm, Rt: The reason for limiting to 6 ~ 30 μm is that Ra is 1.0
Below, sufficient roughness cannot be obtained after rolling, and 3.0 μm
In the above case, the roughness is too large and exceeds the target value when transferred to a metal plate. The reason for Rt is also the same, but since the variation due to location becomes large when this value becomes large, the upper limit was set to 30 μm.

In the present invention, in finish cold rolling, the surface roughness is Ra: 0.5 to 2.0 μm, Rsk: 0 to.
The reason for using a work roll of −2.0, Sm: 50 to 200 μm is that the transfer rate to the metal plate during finish rolling is 50 when converted to Ra.
It is up to 70%, and by making the profile convex downward (Rsk negative), the transferred metal plate has a good profile convex upward.

The materials used in the present invention are
C: 0.02 wt% or less, Mn: 0.5 wt% or less, Si: 0.2 wt% or less, Cr: 0.5 wt% or less, Ni: 30 to 45 wt%, P: 0.01 wt%
Below, S: 0.01 wt% or less, Al: 0.1 wt% or less, balance Fe and unavoidable impurities wt%, balance Fe consisting essentially of Fe-
It is desirable to use a Ni alloy. Of course, it is also possible to use low carbon aluminum killed steel.

The reason why the surface texture of the material according to the present invention, that is, the metal plate for the shadow mask, is limited as described above will be described below. Ra in the surface roughness of the product is a parameter that represents the average size of the roughness, and if this value is too large, the scattering at the time of exposure becomes strong and the difference in the starting time of the holes during etching causes the shape of the holes. Deteriorate. On the other hand, if it is too small, the vacuum evacuation is not sufficiently performed, resulting in poor adhesion between the pattern and the material. As a roughness that satisfies these requirements, the inventors have found that the centerline average roughness Ra is 0.2
It was found that it is necessary to set the thickness within the range of ~ 1.5 μm. The range is more preferably 0.4 to 1.0 μm.

Rsk, which indicates the relativity of the surface roughness, is a parameter that directly indicates whether the pattern is convex or concave, and the symmetry of the amplitude distribution curve (ADF) distribution with respect to the center line is calculated according to the following equation. It is represented by. Rsk = 1 / σ ³ ∫Z ³ P (z) dz where σ is the mean square ∫Z ³ P (z) dz indicates the third moment of the amplitude distribution curve. When the value of Rsk becomes negative and increases, The scattering at the time of exposure becomes strong and the shape of the holes becomes poor. On the other hand, if the value is positive and too large, the evacuation of the vacuum is not sufficiently performed, resulting in poor adhesion between the pattern and the material. According to the research conducted by the inventors, it has been found that a range of 0.5 to 2.0 is desirable for the Rsk value indicating the roughness. More preferably, the range is 0.5 to 1.0.

Further, the roughness Sm, which indicates the average crest interval, represents the size of the pitch of the crests and valleys of the roughness. If it is too large, partial vacuuming failure occurs, and if it is too small, scattering during exposure is strong. This results in a defective hole shape. In the present invention,
It was found that the roughness display Sm value is preferably in the range of 50 to 200 μm. The range is more preferably 70 to 120 μm.

[0026]

Example In this example, in the case of the production method of the present invention, a hot forged Fe-Ni alloy was used as a raw material after vacuum degassing refining, the slab was hot-rolled, and subsequently cold-rolled. As the process treatment, the first cold rolling is performed, and after the annealing and pickling processes, the second cold rolling is performed.
A thin plate with a thickness of 0.150 mm is obtained through a series of cold rolling and bright annealing. Further, this thin plate was subjected to two-pass rolling at a cold rolling ratio of 10 to 15% by using a rolling treatment roll as finish cold rolling. Conventional manufacturing method: Hot-forged Fe-Ni alloy after vacuum degassing refining is used as a raw material, the slab is hot-rolled, and the first cold-rolling is performed as the subsequent cold-rolling treatment. After performing the annealing and pickling steps, the second cold rolling and bright annealing are performed to obtain a thin plate having a thickness of 0.135 mm. Three-pass rolling was performed at a cold rolling rate of 25 to 30% using a work roll subjected to liquid honing as finish cold rolling of this thin plate.

Table 1 compares the etching characteristics of the alloy sheet produced by the present invention and the alloy sheet produced by the conventional method. From this, it is understood that it is difficult to realize the surface roughness of the present invention by the conventional method, and even if one parameter is satisfied, the other parameters cannot be satisfied. From this, as the etching characteristics of the thin plate according to the present invention, the shape of the opening is clear, the roundness is high, and the unevenness (mottling) in the display tube is good.

[0028]

[Table 1]

FIG. 3 shows a conventional method (liquid honing roll).
And the hole diameter distribution of the shadow masks produced by the method of the present invention. This is obtained by measuring the area of the etching through holes of the flat mask by an image analysis method, and by making a histogram of the average hole diameters of 50 holes by this. According to the present invention, the standard deviation is about 20% better than the standard deviation.

FIG. 4 shows the roughness profile of the shot roll, FIG. 5 the roughness profile of the liquid honing roll, and FIG. 6 the roughness profile of the roll according to the invention. In the shot roll, waviness is observed in the cross-section curve, and in the liquid honing roll, there is no waviness, but the steepness of the roughness is large, and there is a concern that scattered light will be generated during exposure. On the other hand, in the roll according to the present invention, no waviness is observed, the overall steepness is small, and when it is transferred to the material surface, an exhaust passage during vacuuming is secured due to the convex profile. I understand. The roll surface roughness in the present invention defines the roughness on the surface of the product, but under the conditions of the present invention, the transfer rate of the roll roughness to the material is about 50%.

FIG. 7 compares the degree of wear of the roll surface roughness between the conventional liquid honing roll and the roll of the present invention. As shown in the figure, it was confirmed that the roll of the present invention was about 5 times as durable as the liquid honing roll. In this case, the increase in processing cost due to the roll rolling treatment is 1.
Since it is about 5 times, it is thought that a significant cost reduction can be expected compared to the conventional case, including reduction of setup during operation.

[0032]

As described above, according to the present invention, the quality of the color display tube can be improved and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a process of a vacuuming process.

FIG. 2 is a sectional view of an exposure process.

FIG. 3 is a graph of hole diameter distribution of a shadow mask.

FIG. 4 is a diagram of a shot blast roughness profile.

FIG. 5 is a diagram of a liquid honing roughness profile.

FIG. 6 is a diagram of the roughness profile of the roll of the present invention.

FIG. 7 is a diagram showing the relationship between roll wear and rolling length.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tsutomu Omori 4-2 Kojimacho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Metallurgical Industry Co., Ltd. R & D Headquarters Technical Research Center (72) Tatsuya Ito Kawasaki, Kawasaki-shi, Kanagawa 4-2 Kojima-cho, Ward, Nihon Metallurgical Industry Co., Ltd.

Claims (5)

[Claims] 1. A metal plate for a shadow mask, which is a metal plate having a surface roughness satisfying the following conditions: Ra: 0.2 to 1.5 μm Rsk: 0.5 to 2.0 Sm: 50 to 200 μm. 2. The metal plate, C: 0.02 wt% or less, Mn: 0.
5 wt% or less, Si: 0.2 wt% or less, Cr: 0.5 wt% or less, N
2. The composition according to claim 1, which has a composition of i: 30 to 45 wt%, P: 0.01 wt% or less, S: 0.01 wt% or less, Al: 0.1 wt% or less, and balance Fe and inevitable impurities. Metal plate for shadow mask. 3. A metal plate is used, the surface of which has the following conditions; Ra: 0.5 to 2.0 μm Rsk: 0 to −2.0 Sm: 50 to 200 μm. The surface roughness is Ra: 0.2 to 1.5 μm, R
A method for producing a metal plate for a shadow mask, which comprises producing a metal plate having an uneven surface satisfying sk: 0.5 to 2.0 and Sm: 50 to 200 µ. 4. In the finish cold rolling step, the metal plate is
Ra: 1.0 to 3.0 μm, Rt: 6 to 30 μm The surface of the roll, which has been subjected to grinder polishing, is subjected to roll rolling treatment from 100 to 10,000 times, and the surface obtained is Ra: 0.5 to
By using a work roll having a surface hardness Hv of 800 or more with 2.0 μm, Rsk: 0 to −2.0, Sm: 50 to 200 μm, and finishing rolling at a rolling reduction of at least 5 to 20% per pass. , Surface roughness Ra: 0.2 to 1.5 μm, Rsk: 0.
A method for producing a metal plate for a shadow mask, which comprises producing a metal plate satisfying 5 to 2.0 and Sm: 50 to 200 µm. 5. The metal plate, C: 0.02 wt% or less, Mn: 0.
5 wt% or less, Si: 0.2 wt% or less, Cr: 0.5 wt% or less, N
5. The composition according to claim 3, wherein i: 30 to 45 wt%, P: 0.01 wt% or less, S: 0.01 wt% or less, Al: 0.1 wt% or less, and the balance Fe and unavoidable impurities.
A method for producing a metal plate for a shadow mask according to.