JPH05144384A - Material for shadow mask - Google Patents

Abstract

PURPOSE:To provide a fine-grained material for a shadow mask by which a color difference is hardly caused and which is suitable for realizing a color television to display a distinct image. CONSTITUTION:A raw material for a shadow mask is mainly composed of nickel and iron, and dislocation density of crystal grains at least in a surface layer exceeds 10<11>(d) 1/cm<2>. Or the raw material contains the nickel by 25-50% in weight %, and contains further cobalt by 2-10% if necessary, and the residual part is composed substantially of iron. It is low thermal expansion alloy having a coefficient of thermal expansion equal to or smaller than the 7X10<-6>/ deg.C, and the crystal grains are also equal to or larger than the grain size number (according to JISG551) 13. This material for the shadow mask can be manufactured easily by cooling/transforming a melted body (molten metal) of the low thermal expansion alloy rapidly into a thin plate by means of a twin roller method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask material suitable for a shadow mask construction of a color television, for example.

[0002]

2. Description of the Related Art Generally, a shadow mask for a color television is made of rimmed steel or Al-killed steel which has a good etching property and a good formability and which easily forms an oxide film on the surface to reduce the reflection of an electron beam. .. However, in order to support various new media, in order to improve the quality of color cathode-ray tubes, in other words, for the viewability and fineness of the displayed image, the shadow mask made of the rimmed steel or Al-killed steel is as follows. There is a disadvantage. That is, when the color cathode ray tube operates, the temperature of the shadow mask rises to 30 to 100 ° C. to cause thermal expansion, so that so-called doming occurs due to distortion of the shape of the shadow mask. As a result, the relative positional relationship between the shadow mask and the fluorescent screen is deviated, and a color misregistration referred to as beauty drift (PD) occurs. Especially in the case of high-quality color cathode ray tubes, the diameter and pitch of the electron beam passage holes of the shadow mask are very small,
There is a problem that the ratio of the relative deviation amount of the electron beam passage hole increases.

In response to these problems, color televisions,
For example, 36% by weight nickel-iron (36% Ni-F)
Attempts have been made to use amber alloys centered on e). That is, since the amber alloy has a small coefficient of thermal expansion, when used as a shadow mask, even if the shadow mask is heated by the collision of electrons, it is difficult for the electron beam passage hole to be displaced, resulting in a color shift. This is because it is easy to prevent The material for the shadow mask of the amber alloy type is manufactured through the steps of melting the raw material material, hot forging, hot rolling, annealing, and adjusting rolling, and adjusting the amber alloy thus obtained. For rolling,
Even if it is said that the crystal grains are fine, it is 6 μm or more (12 or less in the grain size number specified in JIS G0551).

[0004]

However, with the development and practical use of a large-sized and high-definition color TV, the shadow mask is also formed with high precision and fine electron beam passage holes (open holes). ) Is being demanded. In other words, it is desirable for the shadow mask material to have a small coefficient of thermal expansion and to be capable of forming required fine electron beam passage holes with high precision. However, in the conventional Amber alloy, the crystal grains are fine. Even if it is 6 μm or more,
Looking at the etching rate, the etching rate is about 1/3 lower than that of the above-mentioned rimmed steel or Al killed steel,
There is a problem of poor productivity, which is still not satisfactory. In other words, the finer the crystal grains are, the finer the openings having the inner wall surface with good smoothness can be formed by photoetching.
It is hard to say that the conventional amber alloy with a size of μm or more is sufficient.

On the other hand, as a material for a shadow mask with improved etching properties, nickel (Ni) and iron (Fe) are the main components, and the dislocation density in the crystal grains is selected and set to 10 ¹¹ dl / cm ² or less. The materials that have been made are also known. In other words, in the process of melting the required raw materials and performing the processes of hot rolling, annealing, and controlled rolling, the temperature, time, cooling rate, etc. during annealing are carefully selected and combined, and the dislocation density in the crystal grains is It is also known that the shadow mask is composed of a Ni-Fe-based metal whose C is controlled to 10 ¹¹ dl / cm ² or less. However, the dislocation density in the crystal grains is controlled to 10 ¹¹ dl / cm ² or less.
In the case of Fe-based metal, although the etching property is improved, it is difficult to say that the etching rate is sufficiently high, and the problem of poor productivity still remains.

The present invention has been made in view of the above circumstances, and has a small coefficient of thermal expansion and at least a relatively high dislocation density in the crystal grains of the surface layer, or the crystal grains are finer and have good etching properties. An object of the present invention is to provide a material for a shadow mask in which a required fine electron beam passage hole can be formed with high accuracy.

[0007]

A first shadow mask material according to the present invention contains nickel and iron as main components,
And the dislocation density in the crystal grains of the surface layer is at least 10 ¹¹ dl / cm
^{The second} shadow mask material is 25 to 50% by weight of nickel, and the balance is substantially iron or iron-cobalt based iron, and has a thermal expansion coefficient. It is a low thermal expansion alloy with a coefficient of 7 × 10 ^-6 / ° C or less, and the grain size is 13 or more (according to JIS G0551).

As described above, the first shadow mask material according to the present invention is controlled in the Ni-Fe system so that the dislocation density in the crystal grains of the surface layer exceeds 10 ¹¹ dl / cm ^2. The grain size is preferably also the grain size number (JIS G055
(Depending on 1) 8 or more, more preferably 13 or more. The composition ratio in the Ni-Fe system is Ni by weight in order to keep the coefficient of thermal expansion below 9 × 10 ^-6 / ° C.
25-45%, the balance is preferably essentially Fe,
For example, in order to arrange the crystal grains, the weight ratio should be about 7% or less.
Co may be added, or Cr may be added in an amount of about 5% by weight or less in order to reduce disentanglement. Here, the dislocation density in the crystal grains of at least the surface layer (about 10 nm to 0.05 mm) was selected and set so as to exceed 10 ¹¹ dl / cm ² because the wettability with the etching solution (usually FeCl ₂ ). And to obtain rapid etching property, at least the dislocation density in the crystal grains of the surface layer is selected to be 10 ¹¹ to 10 ¹³ dl / cm ^2.
It is more desirable to control. Furthermore, in the Ni-Fe system, B and N, in order to control the crystal grains and dislocation density,
It may be replaced by a precipitation hardening component such as Ti, Al, Zr, Nb, Ta, or Cu. As unavoidable impurities, for example, Cr is 0.2% or less by weight ratio, C is 0.02% or less, Al is 0% or less. .
02% or less, S 0.0% or less, P 0.1% or less, Mo 0.02
% Or less, Co 0.1% or less, nitrogen 50 ppm or less, oxygen 10
0 ppm or less, Mn as a deoxidizer of 0.5% or less, Si of 0.1
% Or less may be included.

The dislocation density (ρ) in the crystal grains can be measured by various methods, and the fastest method is the Ham method. In this method, the sample to be measured is first thinned by etching and then transmitted electron microscope (TEM)
Directly observe and take, for example, about ten tens of thousands of photographs so that dislocations can be easily observed.
If N is the number of lines intersecting with the dislocation line, the following equation is obtained. ρ = 2 N / L _t ρ: Dislocation density (unit is dislocation line / cm ² ) t: Thickness of sample slice Then, the average dislocation density is calculated from this formula.

The second shadow mask material according to the present invention comprises, by weight, 25 to 50% Ni or 25 to 50% Ni and
A low thermal expansion alloy containing 2 to 10% of Co, the balance being substantially iron, having a thermal expansion coefficient of 7 × 10 ^-6 / ° C or less, and having crystal grains with a grain size number (according to JIS G0551) of 13 or more, preferably Is 16 or more. Here, the coefficient of thermal expansion is 7 × 10 ^-6 /
Examples of the low thermal expansion alloy having a temperature of ℃ or below include the so-called amber alloy described above, and super-amber alloy (32Ni-5
Co-63Fe), etc., and a part (within a few percent) of the Ni component of the amber alloy may be replaced with, for example, Ti, Al, Zr, Nb, Ta, Cr, Cu, etc. As the impurities, for example, Cr is 0.2% or less by weight, C is 0.02% or less, Al is 0.02% or less, S is 0.0!% Or less, P is 0.1% or less, Mo is 0.02% or less, Co is 0.1% or less. , Nitrogen 50 ppm or less, Oxygen 100 ppm or less, Mn as a deoxidizer of 0.5% or less, Si may be 0.1% or less. However, it is required that the coefficient of thermal expansion is 7 × 10 ⁻⁶ / ° C. or less and that the crystal grains are fine grains having a grain size number (according to JIS G0551) of 13 or more. The reason is that if the coefficient of thermal expansion is not less than 7 × 10 ^-6 / ° C, the electron beam passage hole will be misaligned due to the temperature rise due to electron collision, and the crystal grains will have a grain size number (according to JIS G0551).
This is because it was experimentally confirmed that the electron beam passage hole having the inner wall surface with good smoothness could not be formed with high accuracy unless the above conditions were satisfied. According to the present invention, when the hole diameter of the electron beam passage holes in the shadow mask is set to about 100 μm, the number of crystal grains existing in these holes is about 10 ⁷ or more, and the crystal grains are The number of crystal grains with a grain size number (according to JIS G0551) No. 12 or less is approximately 5 x 10 ⁶ or less.

According to the present invention, a melt of a Ni-Fe alloy such as a so-called amber alloy is rapidly cooled by a twin roll method and then cold rolled and annealed repeatedly to form a thin strip, or a twin roll method is used. If it is rapidly cooled to a thin film or a ribbon with a thickness of about several mm, and if necessary, after annealing, it is cold rolled into a thin plate of, for example, 0.13 to 0.25 mm. The inventors have found that the electron beam passage hole having a uniform diameter can be easily formed (opened) in any case as compared with the above case. In other words, when the dislocation density in the crystal grains exceeds 10 ¹¹ dl / cm ² , it exhibits a rapid etching property and enables fine holes to be formed by etching, or the crystal grains have a grain size number (according to JIS G0551) of 13 or more. In case of, the crystal grain is 1/3
It is based on the knowledge that it is possible to form fine holes by etching by exhibiting a substantially uniform fine state below a certain level.

[0012]

The material for the shadow mask according to the present invention is a low thermal expansion alloy having a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. or less, so that the position shift of the electron beam passage hole formed even when the temperature is increased by the collision of electrons. Not only is the possibility of occurrence of the above-mentioned problem resolved, but at least the surface layer has a relatively high dislocation density in the crystal grains, or the crystal grains as a whole hold a fine state. It is possible to easily and accurately form a large electron beam passage hole.

[0013]

EXAMPLES Examples of the present invention will be described below.

Examples 1 to 6 Alloys having the compositions shown in Table 1 were prepared, melts prepared by melting each of them at a melting point or higher were poured onto twin rolls rotating at high speed and rapidly cooled to a thickness of 2 mm and a width of 800. A thin plate of mm was obtained. After vacuum annealing (annealing) these thin plates at 800 ° C for an hour,
Cold rolling was performed at a reduction rate of 94% to obtain a shadow mask material having a thickness of 0.15 mm.

With respect to each of the shadow mask materials obtained above, the results of measuring the dislocation densities inside the crystal grains in the surface layer and inside by the above-mentioned measuring method of the dislocation densities inside the crystal grains are also shown in Table 1. Indicated. Comparative Example 1
As a result, the dislocation density in the crystal grains of the surface layer obtained by repeating forging, hot rolling and cold rolling from the ingot is 10 ¹¹ dl / cm 2.
The case of ² or less is also shown. (Below margin) Photoresist is applied to both sides of each of the shadow mask materials described above, dried, and then a film having a slot or dot-shaped reference pattern formed on the resist film surface is closely arranged, and the resist film is exposed and developed. did.
After this development, the photoresist in the unexposed area is dissolved and removed, and the exposed shadow mask material surface is selectively etched with FeCl ₂ solution using the remaining resist pattern as a mask to open electron beam passage holes. A hole was made. After that, the resist pattern functioning as a mask was removed by a hot alkaline solution to manufacture a flat mask which became a master plate of the shadow mask. The etching rates of the FeCl ₂ solution in the flat mask manufacturing process were measured, and the results were as shown in Table 1. The etching rate is a relative value when the value of Comparative Example 1 is 1. Next, each of the flat masks obtained above was annealed at 830 ° C. in a H ₂ stream to reduce the yield strength, and then warm pressed at 150 ° C. to finish it into a shadow mask shape. After that, these were washed with trichloroethane vapor and then in a continuous blackening furnace maintained at 690 ° C.
After heating for 20 minutes, in each of the examples, a shadow mask having a black film with good adhesion grown on the surface was obtained. When the color CRT constructed by using the shadow mask of each of these examples was operated, a fine image without color shift was obtained. In other words, it functioned as a color television that provided high-quality images with no discernible color shift.

Examples 7 to 9 A molten metal prepared by melting an alloy having a weight ratio of 36% Ni and the balance substantially consisting of Fe at a temperature equal to or higher than its melting point was poured onto twin rolls rotating at high speed and rapidly cooled to a thickness. A thin plate having a width of 2.5 mm and a width of 800 mm was obtained. This thin plate was annealed at 700 ° C. for 1 hour and then cold rolled at a reduction rate of 94% to obtain a material for a shadow mask having a thickness of 0.15 mm. For the shadow mask material thus obtained, the coefficient of thermal expansion was measured by a conventional method to find that it was 1.2 ×
The particle size was 10 ⁻⁶ / ° C. and the crystal grains were measured according to JIS GO551. As a result, the grain size was No. 17 (particle size: about 1 μm) or less.

After the material for a shadow mask (Example 7) obtained above was cut into a predetermined size, a required electron beam passage hole was formed (opened) by so-called photo-etching. Observation of the shadow mask material in which the electron beam passage hole was formed (opened) revealed that the inner wall surface of the electron beam passage hole had good smoothness as a whole, and the hole of a predetermined size was formed with high accuracy. Was there. In addition, since this shadow mask material exhibits excellent mechanical strength due to the small crystal grains, it was easy to handle in various operations.

Next, the electron beam passage hole is formed (open hole).
The above shadow mask material was press-molded, and then a blackening film was attached to form a shadow mask, and a color television was constructed using this shadow mask. Then, when the color television configured as described above was operated, a finely detailed image without color misregistration was obtained. In other words, it functioned as a color television that provided high-quality images with no discernible color shift.

[0019] In the above, the conditions for quenching the molten metal by flowing it on a twin roll rotating at a high speed are changed, and the crystal grains according to JIS GO551 have a grain size number No. 14 (grain size about 3 μm).
… Example 8, except for the composition being 32Ni-5Co-63Fe, obtained in the same manner as in Example 7 and having a grain size number of No. 17, which is the material for the shroud mask ... Example 9 ... and Example 7 Only the material for the shadow mask of Comparative Example 2 having only No. 12 as the particle size number (about 6 μm in particle size) was prepared, and the shadow mask was prepared by the same processing and processing as above, and the shape of the electron beam passage hole was examined. The results are shown in Table 2. (Below margin)

[0020]

As described above, the shadow mask material according to the present invention has not only a small coefficient of thermal expansion but also a dislocation density in the crystal grains of more than 10 ¹¹ dl / cm ^2. Alternatively, a fine grain type with a grain size of No. 13 or more according to JIS G0551 is particularly selected. Therefore, for example, in the formation (opening) of the electron beam passage hole by photoetching, the electron beam passage hole having a uniform hole diameter can be formed with high accuracy, and the electron beam passage hole due to the temperature rise due to the collision of electrons can be formed. The position shift is also prevented, and when it is put into a color television and put into practical use, a clear and fine (high quality) image can be obtained without causing color shift. Moreover, when the dislocation density in the crystal grains exceeds 10 ¹¹ dl / cm ² , the material for the shadow mask is quickly etched in the formation (opening) of electron beam passage holes by the photoetching. The productivity can be greatly improved by the properties, and when the crystal grains have a fine grain size of No. 13 or more, they not only have excellent howling resistance, but can be easily processed by the so-called twin roll quenching method. It also has the advantage that it can be manufactured.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Mori 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company Toshiba Yokohama office

Claims (2)

[Claims] 1. A material for a shadow mask, which is mainly composed of nickel and iron and has a dislocation density in crystal grains of a surface layer of at least 10 ¹¹ dl / cm ² . 2. A low thermal expansion alloy having a thermal expansion coefficient of 7 × 10 ⁻⁶ / ° C. or less, comprising 25 to 50% by weight of nickel, the balance being substantially iron or an iron-cobalt system containing iron as a main component. In addition, the material for shadow masks is characterized in that the crystal grain size is 13 or more (according to JIS G0551).