JPH0845424A - Thin plate of iron-nickel alloy with excellent etching characteristic for color picture tube - Google Patents

Abstract

PURPOSE:To provide a thin plate of Fe-Ni alloy ensuring free from irregular etching at a shadow mask etching process. CONSTITUTION:In this thin plate, the component segregation rate A of nickel determined by the following formula is 10% or less, a segregated section in unit volume is 14vol% or more, and the length of one segregated section immediately before an etching process is 35mm or above. The formula is A=[{(component concentration in segregated area)-(mean component concentration)}/(mean component concentration]X100(%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube F which is used as a shadow mask material or an aperture grill material for a color television CRT and has excellent etching characteristics.
The present invention relates to an e-Ni alloy thin plate.

[0002]

2. Description of the Related Art Mild steel is generally known as a shadow mask material for color television picture tubes and an aperture grill material. In a color television cathode ray tube, electron beams emitted from three electron guns pass through minute holes formed in a shadow mask and are precisely applied to a predetermined point on a fluorescent screen to give a specific color tone. It is what is done.

However, when such a cathode ray tube is continuously used, the temperature of the fluorescent screen supported by the glass body irradiated with the electron beam and the shadow mask are gradually increased. In particular, the shadow mask has a considerably higher temperature than the fluorescent screen supported by the glass body, and the thermal expansion coefficient of the shadow mask is much larger than that of the glass body. The beam is not radiated accurately and the image becomes unclear. For this reason, it has been attempted to devise a structure of a support body which is a suspension device of the shadow mask to compensate for it, but this is not sufficient.

Therefore, as a shadow mask material,
It has been proposed to use low thermal expansion materials such as iron-nickel alloys such as Amber. However, such a shadow mask material made of an iron-nickel-based alloy causes defects called etching unevenness when the etched shadow mask is visually observed with oblique light during photoetching perforation in the step of manufacturing the shadow mask. I found out. This unevenness contains Ni of 30 to 55 wt.
% Of Fe-Ni alloy or Fe-Ni alloy containing 1 wt% or less of sub-components. In order to improve such unevenness, an invar material having a component segregation ratio of 10% or less and a segregation portion in a unit volume of 5% by volume or less has been proposed as disclosed in JP-A-60-56053.

[0005]

However, although this technique can improve the streak unevenness of a shadow mask having a normal hole diameter pitch, when it is etched as an ultra-high-definition shadow mask having a hole diameter pitch of 300 μm or less, the unevenness peculiar to the Invar material still occurs. There is a problem of doing.

This etching unevenness is an unevenness that appears linear when the etching mask is viewed with oblique light.
It occurs remarkably strongly when an i-based alloy thin plate is etched into a pattern of an ultra-high definition shadow mask. Since this unevenness causes color shift of the screen on the product, it has been strongly desired to eliminate it.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is an Fe-Ni alloy, particularly Fe-Ni containing 30 to 55 wt% of Ni.
Fe, containing alloys and 1% by weight or less of subcomponents
An object of the present invention is to provide a material that does not cause uneven etching in the production of a high-definition type shadow mask made of a Ni-based alloy and having a pore size of 300 μm or less.

[0008]

The thin Fe-Ni alloy plate for a color picture tube according to the present invention, which is excellent in etching characteristics, has a Ni component segregation ratio A of 10% or less, which is defined by the equation 2, in a unit volume. The segregation portion is 14% by volume or more, and one length of the segregation portion immediately before etching is 35 mm or more.

[0009]

[Equation 2]

[0010]

The present inventor contains 30 to 50 wt% of Ni having low thermal expansion and excellent soft magnetic characteristics, and further contains 1 wt% of a subcomponent.
As a result of various studies on the etching unevenness of the Fe-Ni alloy thin plate containing 1% or less, the Ni weight% is 3%.
It was found that when the content is 0 wt% or more, strong etching unevenness appears and there is a strong correlation with the Ni concentration.

That is, the present inventors have found that the Ni component segregation ratio A defined by the equation 3 is 10% or less, the segregation portion in a unit volume is 14% by volume or more, and the segregation portion 1 immediately before etching is 1%.
By setting the length of one to be 35 mm or more,
It was found that unevenness during etching can be suppressed.

[0012]

(Equation 3)

As shown in FIG. 1, when the shadow mask 1 is etched in the segregated portion with an etchant (the etchant is corroded by ferric chloride), the Ni-enriched portion 2 appears clearly linearly.

In the above segregation portion, no peculiar unevenness is seen on the surface of the shadow mask 1 and it is continuous, but as can be seen from the X-ray intensity shown in FIG. Continuity is seen, and it is clear that there is a Ni segregation part. Further, from FIG. 2, the weight% of the segregated portion can be measured from the size of the X-ray strengthened portion, and the segregated portion and the other portion can be theoretically distinguished from each other by comparing the respective average component concentrations. I will get it. The segregation portion in the present invention means a Ni enriched portion with respect to the average component concentration, and the segregation region is a total of each segregation portion, and the component concentration in the segregation region is the total concentration of components in each segregation portion. Concentration (average concentration)
Is shown.

Next, the reasons for limiting the Ni segregation portion and the like which constitute the material of the present invention will be described. The reason why the Ni component segregation ratio A defined by the equation 4 is 10% or less is that the Ni component segregation is 10% or less.
%, The difference in etching property from the base material becomes remarkable,
This is because unevenness during etching of the high-definition mask, which is a feature of the present invention, becomes remarkable.

[0016]

[Equation 4]

The reason why the segregation portion is set to 14% or more in a unit volume is that if it is less than 14%, the proportion of the segregation portion is small, so that it appears conspicuously as an uneven portion as compared with the non-segregation portion. Because it will come.

The reason why the length of one of the segregated portions is 35 mm or more in the material before etching is that if the length is less than 35 mm, it can be remarkably observed in the flat plate even if the unit volume ratio of the segregated portion is 14% or more. ., 35% or more, the proportion of the total increases, and it becomes less visible as unevenness.

By strictly controlling the Ni segregation rate, the distribution state and the size of the segregated portions in this manner, the occurrence of etching unevenness can be suppressed for the first time in an ultrahigh-definition mask having a hole diameter pitch of 300 μm or less. Moreover, due to the characteristics of these materials having a low coefficient of thermal expansion, the image has an extremely excellent feature that it becomes clearer. As a manufacturing means for satisfying these conditions, the cumulative reduction rate in hot working at a temperature of 800 ° C. or higher is set to 98.1% or more and 99.8% or less. As shown in the graph of FIG. 3, which shows the relationship between the cumulative reduction ratio, the ratio of the segregation portion in the unit volume, the length of one of the segregation portions and the Ni component segregation ratio, the cumulative reduction ratio is less than 98.1%. When the Ni component segregation rate exceeds 10%, the length of one of the segregation portions is less than 35 mm, etching unevenness occurs, and when the cumulative reduction rate exceeds 99.8%, This is because the ratio becomes less than 14%, and uneven etching occurs in each.

[0020]

EXAMPLES Among the alloys of the present invention shown in Table 1, No. 1 to
Nos. 4 and 8 were ingot-cast and then slab-rolled to form slabs.
Nos. 5 to 7 and 9 were continuously cast to form a continuously cast slab, which was then heated in a heating furnace to perform hot rolling to obtain a hot rolled steel sheet. In the hot rolling at this time, the cumulative rolling reduction of 800 ° C. or higher was 9
It was set to be not less than 8.1% and not more than 99.8%.

Then, cold rolling was performed using the obtained hot rolled steel sheet as a raw material to obtain a thin sheet having a thickness of 0.12 mm.

From the thin plate produced in this way, Table 1
Test material No. The test materials 1 to 9 were sampled, and each test material was photoetched with a hole diameter of 230 μm and a hole pitch of 300 μm, and then the presence or absence of etching unevenness was investigated. Table 1 shows the results.

[0023]

[Table 1]

As shown in Table 1, the shadow mask material made of the alloy obtained by the present invention is a conventional Fe--Ni alloy.
Compared to the shadow mask material made of the system alloy, there is no unevenness during etching, and it is clear that it is an excellent material for the shadow mask.

[0025]

According to the present invention, the shadow mask is free from unevenness during etching.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a Ni segregation portion after etching.

FIG. 2 is a chart showing the measurement results of X-ray intensity distributions of Ni and Fe in the II cross section of FIG.

FIG. 3 is a graph showing the relationship between the ratio of the segregation portion per unit volume, the Ni component segregation rate, the length of one segregation portion, and the cumulative reduction rate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isamu Kage 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Wakasa 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. The Ni component segregation ratio A defined by the equation 1 is 10% or less, the segregation portion in a unit volume is 14% by volume or more, and the length of one segregation portion immediately before etching is 35 mm or more. An Fe-Ni alloy thin plate for a color picture tube, which is excellent in etching characteristics. [Equation 1]