JPS63128119A - Manufacture of metallic sheet for shadow mask - Google Patents

Abstract

PURPOSE:To obtain an Fe-Ni alloy sheet having superior etchability by which holes of uniform diameter and shape are pierced and giving a high quality shadow mask causing no irregularity by carrying out final cold rolling at a specified draft. CONSTITUTION:An Fe-Ni alloy is melted, cast, forged, hot rolled and pickled. In is subjected to properly repeated cold rolling and annealing, the grain size is regulated to grain size No. >=7 by annealing before final cold rolling and the final cold rolling is carried out at >50% draft to manufacture a metallic sheet. When holes for passing electron beams are pierced the metallic sheet by etching, a high accuracy shadow mask for a color image receiving tube can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a thin plate for a shadow mask used in a color picture tube, and particularly to a method for manufacturing a thin plate for a shadow mask as a blank material for forming an aperture for passing an electron beam in a shadow mask by etching. The present invention relates to a method for manufacturing thin plates for shadow masks with high productivity and high quality. The present invention is characterized by the control of the final cold working degree and the grain size in the annealing before that, which makes it possible to manufacture high-definition shadow masks without unevenness. This will greatly contribute to the manufacture of quality televisions and the like.

Background of the Invention Conventionally, mild steel plates such as low carbon rimmed cold rolled steel plates and low carbon Al killed cold rolled steel plates have been used for shadow masks for color picture tubes. i-based alloys, e.g. 36Ni-Fe
Various uses of amber are being considered.

Generally, when a color picture tube is operated, less than 173 of the electron beams pass through the apertures of the shadow mask, and the remaining electron beams impinge on the shadow mask.
The shadow mask is heated to a temperature of 80 degrees Celsius during the process. At this time, the shadow mask expands due to heat, and the distance between the shadow mask and the fluorescent surface changes, resulting in a decrease in color purity. However, the use of Fe-Ni-based amber alloy reduces this thermal expansion. It is said that it will be done.

However, it is difficult to say that the Fe--Ni alloy also meets all the requirements as a shadow mask material.

There are problems such as poor press moldability, buckling of the molded mask, and other problems, many of which have been solved or are being solved through the efforts of the applicant and others.

One of the remaining problems with the Fe-Ni shadow mask, whose practical application is rapidly progressing, is as follows:
Compared to conventional mild steel, it has the ability to be etched to open a large number of pores for the electron beam to pass through.

In the case of Fe-Ni alloys, resist adhesion and corrosion resistance to etching solutions are different from those of mild steel, so conventional etching drilling methods (1) have poor productivity due to slow etching speed, and (11) have poor hole diameter and The variation in shape becomes large, and as a result, when light is transmitted through the pores formed by nuclear etching, a hazy-like unevenness occurs in the mask. In particular, in high-definition masks with small pitches and small hole diameters, which have been rapidly increasing in recent years, even slight disturbances in the hole diameter or shape can cause unevenness, significantly degrading the quality of color picture tubes. Conventionally, measures have been taken to improve the etching properties of Fe-Ni based shadow mask thin plates, such as considering the material quality and, in particular, regulating the content of impurities such as C and N. However, for high-definition shadow masks, However, this boiling is not sufficient from the above-mentioned viewpoints of productivity and etching performance. In addition to these, F
There is a demand for the development of e-Ni based alloy thin plates for shadow masks.

SUMMARY OF THE INVENTION The present inventors have investigated the problem of improving productivity and eliminating unevenness of the Fe--Ni alloy shadow mask mentioned above from various angles. As a result, the etching speed can be increased by incorporating processing strain and tightening the crystalline wires, and the etching performance can be improved by making the crystal grains finer and removing harmful surface layers. With this in mind, we conducted research on specific countermeasures. As a final conclusion, in order to easily realize these, (1) Final cold rolling should be performed with a degree of hard working of 50% or more, (li) Q Before final cold rolling, the grain size should be changed to grain size number 10. We have learned that it is best to control the situation as much as possible.

Thus, the present invention provides: <1) A Fe-Ni alloy subjected to an etching process for forming an opening for passing an electron beam, characterized in that the final cold rolling is performed at a working degree of more than 50 inches. A method for manufacturing a metal thin plate for a shadow mask, and (2) annealing the metal sheet to a grain size number of 7.0 or more, followed by final cold rolling at a working degree of over 50 inches. A method of manufacturing a metal thin plate for an Fe--Ni alloy shadow mask which is subjected to an etching process to form an opening for electron beam passage is provided.

Many Fe--Ni alloys for shadow masks have been proposed so far. A few examples are shown for reference, but it goes without saying that the present invention is by no means limited to these and is intended for all austenitic alloys based on Fe-Ni. do not have.

Example 1 (Remaining Fe and unavoidable impurities) Cα 10% or less S α 30% or less Al 130% or less Mn α1~tO Ni 34. O~3&0chi Example 2 Example 1 + (T l s Z r * I3 e M
o , N b , P + Cu e V e M g
@ Co g W ) one or more 0.01 to t Ochi Example 3 (remainder Fe and unavoidable impurities) CO, 10 or less St Q,! 10% or less A I 0.50 or less M n α1~to%N1
60-45 Cr 2. O~1 α0chi Example 4 Example 2+ (Ti, Zr, Mo, Nb, B, v.

One or more types of Be) 0.01 to t O% Example 5 (Remaining Fe and unavoidable impurities) yl no,
1 to t O% NL 3α0 to 340% Crto to 4.0% CO2, 0 to 5.0% C, 3, O, N, etc., which tend to form nonmetallic inclusions that impair etching perforation properties in such alloy compositions Trace impurities are also regulated to low levels.

Shadow masks are produced by processing alloys with the five compositions mentioned above through hot processing processes such as melting (vacuum, VOD, AOD, etc.), casting, forging, hot rolling, and pickling, and then roughly dividing them into the following two types. It is produced by two methods: (I) General method (method in which annealing is performed immediately before press molding to impart press formability) This method involves repeating cold rolling and annealing as appropriate, and final cold rolling to form a shadow mask. After manufacturing the gold pA'14 plate, degreasing, resist coating, and development, there is a drilling process to form an opening for electron beam passage, a cutting process to form a flat mask, and an annealing process to impart press formability. , a shadow mask is manufactured through a press molding process to form the mask and a blackening process to form a black film on the surface.

(I [) Pre-annealing method (method in which annealing to impart press formability is performed immediately after final cold rolling) This is a method in which a shadow mask thin plate is manufactured through the final rolling process in the same manner as above, and then press forming is performed. After performing annealing 1 (called final annealing) to impart properties, skin pass cold rolling if necessary, degreasing, resist coating, and development.
A shadow mask is manufactured through a drilling process for forming an opening for passing an electron beam, a cutting process for forming a flat mask, a press molding process similar to that described above, and a blackening process similar to that described above.

The present invention is basically applicable to both methods (I) and (n), but is particularly applicable to method (I).

As described above, the present invention is characterized by strong working in the final cold rolling and, in addition, grain refinement in the annealing before the final cold rolling.

First, if the final rolling is performed at a high degree of working, large working distortions will remain inside the thin metal sheet for the shadow mask during etching. Corrosion progresses faster in the presence of distortion, so the etching speed increases when processing distortion remains. As a result, the etching speed of the highly worked rolled material becomes faster. Since this effect appears when the working degree exceeds 50 inches, the working degree of the final rolling was set to exceed 50 inches.

Next, when the final rolling is performed at a high degree of working, the crystal grains are crushed and the effect of grain refinement is obtained. When the crystal grains are fine, the difference in etching speed due to crystal orientation is averaged out.
In addition, the etching is uniform throughout, and variations in the hole diameter and hole shape of the shadow mask after etching are reduced, and a high-quality shadow mask without unevenness can be obtained. Further, even in annealing before final rolling, the crystal grains are preferably small fl 5, and the grain size number is preferably 70 or more, preferably aO or more. This is 5free at 700-1200℃
This can be achieved by annealing for 5 hours.

Furthermore, it is even more preferable to carry out the final rolling at a high degree of working, since this has the effect of thinning or destroying surface layers that inhibit etching, such as oxidized layers and nitrided layers produced by annealing. That is, a metal thin plate for an Fe-Ni alloy shadow mask is usually manufactured by repeating melting, casting, forging, hot rolling, and pickling, followed by cold rolling and annealing. At that time, annealing is performed using a mixed gas of hydrogen and nitrogen (ammonia decomposition gas).
Since etching is performed inside the shadow mask material, an oxide layer and a nitride layer called a BA film are formed on the surface of the shadow mask material, which has a negative effect on the etching properties, and it is better to destroy this to improve the etching properties. It is. In connection with this, if the oxide layer and nitride layer are removed by pickling, chemical polishing, etc. after annealing, the etching properties will be improved and the occurrence of unevenness after etching can be suppressed. Further, the present inventors have also confirmed that the generation of such a harmful layer can be suppressed or eliminated by performing annealing in an atmosphere containing 95% or more of hydrogen and the balance being nitrogen. It is also effective to use these together with the present invention.

The plate for shadow mask metal produced in this way is 0
．． It has a thickness of 50 mm or less and is subjected to an etching process. In the etching process, after degreasing and cleaning, a resist film is formed on one or both sides, a predetermined opening pattern is developed, and etching is performed after drying and burning.

Etching is generally performed using a ferric chloride solution.

As described above, in the thin metal plate for shadow mask 5 according to the present invention, etching progresses well in accordance with the opening pattern under the increased etching speed, producing openings with uniform hole shape and size.

A 36% Ni-Fe amber alloy was used as a shadow mask material. This was finally made into a metal thin plate having a thickness of [L2m] under the conditions shown in Table 1. An etching test was conducted using this metal thin plate as a test material.

First, degreasing and cleaning are performed, and then a photosensitive solution consisting of milk caseinate alkali and ammonium dichromate is applied to both surfaces to form a predetermined resist film.

Next, patterns having negative images of large and small mask holes are closely placed on the photoresist films on both sides, and images of the mask holes are obtained by exposing to ultra-high pressure mercury film. After that, it goes through development, drying, and burning before proceeding to the etching process. In the etching process, a ferric chloride solution was used as an etching solution.

The etched mask was observed under transmitted light in a dark room to evaluate the quality of unevenness. The results are also shown in Table 1.

As can be seen from Table 1, the samples of the present invention in which the final rolling was performed with a working degree of over 50 inches had good grain quality after etching. Particularly good results have been obtained with /I61 and 2, in which the grain size after annealing before final rolling is grain size number 70 or more.

As described above, according to the present invention, it is possible to manufacture a metal thin plate for a shadow mask, which can reduce variations in hole diameter and hole shape, and can manufacture a high-quality shadow mask without unevenness.

Claims (1)

[Scope of Claims] 1) For a Fe-Ni alloy shadow mask used in an etching process for forming an opening for passing an electron beam, characterized in that the final cold rolling is performed at a processing degree of more than 50%. Method for manufacturing thin metal sheets. 2) An etching process for forming holes for electron beam passage, characterized by performing annealing so that the crystal grain size becomes grain size number 7.0 or more, and then performing final cold rolling at a processing rate of more than 50%. A method for manufacturing a metal thin plate for a Fe-Ni alloy shadow mask to be used in