JPH01204333A - Shadow mask - Google Patents

Abstract

PURPOSE:To make is possible to manufacture a shadow mask suitable for a high quality color picture tube with no color purity drift by suppressing the dislocation density of a Ni-Fe family alloy less than 10<10>dl/cm<2> so as to improve the etching characteristics in forming of through holes for electron beams (etching holes). CONSTITUTION:In an alloy mainly composed of Fe and Ni, the dislocation density in crystal grains is made to be less than 10<11>dl(dislocation line)/cm<2> and the crystal grain size is made to be 8-12 in grain size number shown in JIS-G0551. By controlling the dislocation density in crystal grains as above, through holes 2 for electron beams on a shadow mask 1 can be etched in high accuracy. The composition of the alloy mainly composed of Fe and Ni can be selected adequately, but an alloy composed of 25-45wt.% of Ni and residual substantial portion of Fe can be used practically. Thereby a shadow mask with the wide bridge portion 3 and low thermal expansion coefficient and good etching characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a shadow mask used, for example, in a color picture tube.

(Prior art) Shadow masks for color picture tubes have traditionally been made of rimmed steel or M-killed steel, which are materials that have good etching and formability and are easy to form an oxide film on the surface that contributes to reducing reflection of electron beams. It is made of steel, etc. however,
In recent years, in order to accommodate various new media, there has been a demand for higher quality color picture tubes, so-called ease of viewing and extremely fine details for images displayed on the screen. There were some problems with using the mask.

That is, when the color picture tube is operated, the temperature of the shadow mask rises to 30 to 100 degrees Celsius, causing thermal expansion.
So-called doming occurs due to distortion of the shape of the shadow mask. As a result, a shift occurs in the relative positional relationship between the shadow mask and the fluorescent surface, resulting in color shift called purity drift (PD). In particular, in high-quality color picture tubes, the diameter and pitch of the electron beam passing holes in the shadow mask are very small, so the relative deviation of the electron beam passing holes is very small. Shadow masks made of M-killed steel are no longer practical.

For this reason, conventionally, it has been recommended to use a Ni-Fe alloy with a small coefficient of thermal expansion, such as amber (36Ni-Fe), as a material for forming the shadow mask.
This method has been proposed in Japanese Patent Application Laid-open No. 2-25446, Japanese Patent Application Laid-Open No. 50-58977, Japanese Patent Application Laid-Open No. 50-68650, etc.

However, this amber has poor etching properties, and to improve this, a method has been devised to align the crystal orientation to (100) (Japanese Patent Application Laid-Open No. 59-40443゜59-1496
38.6O-234921). Although this method greatly improved etching performance, controlling the crystal orientation alone was not always sufficient for shadow masks where the precision of some etching holes was severe.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a shadow mask that has a low coefficient of thermal expansion and good etching properties. be.

[Structure of the invention]

(Means and effects for solving the problems) The present invention contains Fe and Ni as main components, and has an intra-grain dislocation density of l Q dl (dislocation 1ine
)/7 or less. Further, the etching resistance is improved by setting the crystal grain size to a crystal grain size number 8 to 12 as shown in JIS-GO551.

In other words, the present invention has discovered that electron beam passing holes in a shadow mask can be etched with high accuracy by controlling the dislocation density within the crystal grains, and further, by controlling the size of the crystal grains. It has been discovered that the etching resistance of the layer can be improved.

Note that the alloy composition mainly composed of Fe and Ni used in the present invention can be selected as appropriate, but in practice it is 25 to 45 w.
An alloy containing t% of Ni and the remainder substantially consisting of Fe is used. The reason for setting the Ni composition amount to 25 to 45 wt% is to keep its thermal expansion coefficient below 90 x 10/℃, but if it exceeds this range, the formability will deteriorate significantly and the oxidation resistance will improve. Therefore, it becomes difficult to form a blackening film necessary for heat dissipation on the surface of the shadow mask.

In the present invention, it is possible to further add Co, Cr, etc. 5wt% or less of Cr can reduce dislocation entanglement and reduce dislocation density, and 7wt% or less of Co can reduce crystal grains. This makes it easier to align the elements, and further reduces the coefficient of thermal expansion.

There are various methods for measuring the dislocation density (ρ) within a crystal grain in the present invention, but the quickest method is the Ham (H) method.
am) method. In order to directly observe the sample to be measured using a transmission electron microscope (TEM), the specimen is first made into a thin section by etching. This is observed with a TBM, and approximately 10 photographs are taken, for example, at a magnification of tens of thousands of times so that dislocations can be easily observed.

If some arbitrary lines are drawn along the entire length of this photograph and the number of lines that intersect with the dislocation lines is set to N, the following equation is obtained.

ρ=2N/Lt ρ: Dislocation density (unit: dislocation 1in)
e/cIi) t: Sample thin section thickness Calculate the average dislocation density using this formula.

If the dislocation density in the crystal grains is higher than 1Qdl/-, it is likely that etching will occur in the direction of the rolling surface during shadow mask forming, and etching may occur in the direction perpendicular to the rolling surface before etching is sufficiently etched. Etching progresses excessively in the lateral direction. In this case, when used as a shadow mask in which it is difficult to obtain a desired hole shape, color unevenness is likely to occur. Desirably, it is 10 dl/i or less.

In order to control the dislocation density in crystal grains to be low as in the present invention, the annealing temperature during rolling, holding time, and subsequent cooling rate in the shadow mask forming process are controlled. Specifically, the annealing temperature is 600 to 1000°C, the holding time is 5 minutes or more, and the cooling rate is selected in the range of 20°C/min to 200°C/min, and the dislocation density is controlled to 1 Qdl/i or less. do.

Further, when the crystal grains have a grain size number of 8 to 12 as shown in JIS-GO551, even better etching properties can be obtained. If the crystal grain size is less than 8, the crystal grains will become coarse and the desired etched hole may not be formed, and if it exceeds 12, the inner wall of the hole formed by etching will be caused by fine crystal grains. There may be cracks in the holes, resulting in so-called rough holes. These crystal grains are easily influenced by the final rolling rate and annealing temperature during rolling and annealing, and the rolling rate is preferably 40 inches or more, preferably 8096 or more, and the annealing temperature is preferably 600 to 1000°C.

In addition, in order to control crystal grains, B, N, and precipitation hardening components such as Ti, At, Zr, V, Si, Ta, etc. are added to 1.0%.
It can also be added in an amount below wt%.

(Example) Examples of the present invention will be described in detail below.

Example 1 First, 36%Ni-Fe was used as the main component, C was o, oos heavy weight % as the exterminating component, and Si was 0.01% by weight.
An alloy ingot containing 0.001% by weight of each of P and S was prepared by vacuum melting. Subsequently, this ingot was repeatedly rolled, then pickled and subjected to primary and secondary cold rolling. The rolling rate in this process was 80 inches.

Then, in a box-shaped annealing furnace, the temperature was 1 o torr, io
o.

After annealing the rolled alloy plate at ℃, the rolling rate was 3.
Adjustment rolling was performed at Furthermore, strain relief annealing is performed at 400°C.
It was carried out at ℃.

In addition, as a comparative material, an alloy plate was annealed at 800°C for 30 minutes in a H2 stream, cooled at a cooling rate of 100°C/min, then re-rolled at a rolling reduction of 30%, and further subjected to strain and shear annealing at 300°C. I prepared something.

The dislocation density of the above example was 9 x 10 dl/d, while that of the comparative material was 1.3 x 10 dl/cd.

Using the thus produced shadow mask material, a shadow mask was manufactured through the following steps.

First, 7 photoresists were applied to both sides of the material, and after drying, a film on which a reference pattern in the form of slots or dots was formed was adhered to the surface of each resist film, and the resist films were exposed and developed. By this development, the unexposed portions of the photoresist were dissolved and removed. Subsequently, the photoresist patterns formed by development were hardened by burning, and then, using each resist pattern as a mask, the exposed material was etched with a ferric chloride solution to form electron beam passage holes. Thereafter, the resist pattern was removed using a hot alkali to produce a flat mask that would serve as a shadow mask original.

When comparing the etching holes in the example material and the comparative material, as shown in Fig. 1, which is an enlarged plan view of the shadow mask, the shadow mask (1) has an etching hole (2) and a bridge portion (3) between the etching holes. The width of the inventive material is large,
It was smaller in comparison materials.

Thereafter, it was annealed at 1000° C. in a vacuum of 102 Torr to lower its yield strength, and then press-molded into a shadow mask shape.

Next, the shadow mask was cleaned with trichloroethane vapor and heated in a continuous blackening furnace maintained at 690°C for 20 minutes to grow a black film with good adhesion to a thickness of 1.5 m, thereby forming a shadow mask. completed. Since the etching holes do not extend horizontally, the strength of the shadow mask is strong, and the vibration of the shadow mask caused by the sound of the speaker can be reduced. On the other hand, the comparative shadow mask produced vibrations and was difficult to see.

Example 2 First, an ingot of an alloy containing 36% Ni-Fe as the main component, 0.05% by weight of C, 0.02% by weight of Si, and 0.001% by weight each of P and 8 as repellent components was prepared. Produced by vacuum melting. Subsequently, this ingot was repeatedly hot-rolled, and then cold-rolled and annealed to a final rolling reduction of 50 inches.

The final annealing temperature at this time was 950°C, which was held for 4 hours, and then cooled at 50°C/min. In this way, JIS
A shadow mask material having an austenite structure with a grain size of 11 as defined by GO551 was obtained. The dislocation density at this time was 4.5×10 dl/d.

Next, a shim beam passing hole was bored using the shadow mask material in the same manner as in Example 1, and then press molding was carried out using a heater embedded in the mold at a temperature of 200°C. A black film was grown in the same manner as in Example 1 to complete a shadow mask.

As with the actual version 1, the screen had less shaking.

In the above example, a case where amber whose main component is 36% Ni-Fe is used as the material for the shadow mask is explained, but the same effect can be obtained by using other materials whose main component is Ni-Fe. I was able to achieve it.

〔Effect of the invention〕

As detailed above, according to the present invention, a predetermined Ni-Fe
By suppressing the dislocation density of the alloy to 10 dl/i or less, etching performance when forming electron beam passage holes (etching holes) can be improved.

In addition, since etching does not proceed in the direction of the rolling surface of the material, the width between the holes can be increased, resulting in a durable shadow mask. Furthermore, since the Ni--Fe alloy has a smaller coefficient of thermal expansion than rimmed steel or n-killed steel, doming of the shadow mask can be reduced. Therefore, a shadow mask suitable for a high-quality color picture tube without color shift can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view showing an example of the arrangement of electron beam passing holes in a shadow mask. 1... Shadow mask, 2... Etching hole (electron beam passing hole), 3... Bridge portion. Figure 1

Claims (2)

[Claims] (1) A shadow mask containing Fe and Ni as main components and having a dislocation density within crystal grains of 10^1^1 dl/cm^2 or less. (2) The shadow mask according to claim 1, wherein the crystal grains have a crystal grain size number of 8 to 12 shown in JIS-G0551.