JPS59149636A - Manufacture of shadowmask - Google Patents

Abstract

PURPOSE:To form corrosion-resistant oxide film on a shadow mask by making iron composition ratio on the surface of shadow mask containing Fe and Ni as main component more excessive than initial iron composition through iron galvanization thereby forming gray black or black oxide film on the surface. CONSTITUTION:Iron composition ratio on the surface of shadow mask containing Fe and Ni as main component is made more excessive than initial iron composition through galvanization to form grey black or black oxide film on the surface. For example, a thin alloy plate containing 36% Ni and Fe as main component is made of fine holes of predetermined pattern through photoetching. Then vacuum annealing is performed under 1,200 deg.C then applied with leveller lightly to eliminate rumples produced during annealing and iron galvanized. Thereafter it is washed with water, neutralizd, alcohol substituted and dried then a flat mask is pressed and trichlane defat is performed to form an oxide film having thickness of 2mum in ambient gas of CO+CO2+O2 under the temperature of 570-600 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a shadow mask used in a color receiver quadrant.

[Technical background and problems of the invention]

In general, a color picture tube consists of an electron gun that emits three adult beams, and a regularly arranged group of phosphors that emit red, blue, and green light on the inner surface of the envelope panel facing the electron gun. There is a certain distance between the surface and this fluorescent screen (hereinafter q
The shadow mask has a large number of regularly arranged fine apertures that are arranged opposite to each other at a distance (abbreviated as "value").

In a color picture tube with such a configuration, the three screen beams are concentrated near the fine apertures of the shadow mask, disperse again at the Q-value opening, and collide with the specified phosphors in the correct manner to produce a color image. Forbid me to let it out. This shadow mask is normally manufactured through the following steps. That is, a photosensitive layer is applied to a high-purity iron plate of 0.1 sm to 0.3 sm thick of shadow mask material, a predetermined array pattern of fine holes is formed by light exposure, and the fine holes are etched. to drill. Next, the finely apertured surface is press-molded into a curved shape, and the peripheral portion is press-molded into a shape that allows fixation to the mask frame.

Furthermore, a corrosion-resistant grayish-black to black oxide film is formed on the surface of the shadow mask. This oxide film prevents the reflection of ultraviolet rays on the mask surface during the formation of a phosphor screen using a light exposure method via a shadow mask in the subsequent process, prevents rust from occurring up to the tube exhaust, prevents secondary electron emission during tube operation, and prevents electron beams. The purpose is to absorb Various oxidation methods such as steam oxidation, gas oxidation, or alkaline bath oxidation are possible, and the color is grayish-black to black, and generally black is preferable.

In addition, if the thickness of the oxidation is less than 1 μn1 as exemplified in JP-A No. 54-139463, the prevention of rust is insufficient, and if it is thicker than 3 μIn, splashes occur frequently during assembly and welding. 3 μm is preferred.

Now, the material for such a shadow mask is generally 11
An iron material with a purity of 11 is used, but its biggest drawback is approximately 12 X TO'/'' at 100°0.
0, which means that the coefficient of thermal expansion is large. The temperature of the shadow mask is approximately 80' due to the impact of the electron beam.
As a result, the shadow mask causes a doming phenomenon due to thermal expansion, causing the q value to deviate from the designed value depending on the location, causing a landing position shift, and resulting in poor color purity. As a countermeasure against such deterioration of color purity, for example, the thermal expansion coefficient is 5 X to -6 at 0 to 100°C.
It is believed that it is possible to significantly suppress the doming phenomenon by using a low expansion material, ie, an alloy containing iron and nickel as main components.

However, this material whose main components are iron and nickel... has extremely high strength in shallow areas, and its yield point of 1 degree is particularly high compared to iron, so if it is left as it is, it will be press-formed into the specified shape of the shadow mask. It is extremely difficult and unfortunate to do so. Therefore, in order to facilitate press forming, the temperature was set at 1100°○ to 1200°C in a vacuum or in a hydrogen gas atmosphere.
By performing heat treatment at a high temperature, it is possible to obtain a highly satisfactory shadow mask.

However, shadow masks whose main components are iron and nickel are susceptible to rust during the manufacturing process. If the hole is clogged, it will lead to quality deterioration such as pressure deterioration. Countermeasures (As mentioned above, the solution is to form a corrosion-resistant oxide film on the surface of the shadow mask.However, alloys whose main components are iron and nickel cannot be used in an open air or hydrogen atmosphere. in .

It is said that impurities in the steel, such as St, Cr, and Mu(n), precipitate on the extreme surface layer of the shadow mask due to the high-temperature treatment at 1,100°C to 1,200°C, making it extremely difficult to form a tactile coating. I'm fixing the problem.

[Purpose of the invention]

The unexploded method was developed in view of the above points, and its purpose is to form a corrosion-resistant oxide film on a shadow mask made of cable material whose main components are iron and nickel.

[Thanks for the invention/C-an]

The present invention is a method for producing a shadow mask, in which the iron composition ratio on the surface of a shadow mask whose main components are iron and nickel is made to exceed the original iron composition ratio by iron plating, and a corrosion-resistant oxide film is formed.

[Embodiments of the invention]

First, in order to facilitate press molding of a shadow mask mainly composed of iron and nickel, high temperature annealing is performed at 1100° to 1200° C. in hydrogen or vacuum.

Next, 550'0 to 600°0 in a normal single installation atmosphere.
When oxidation treatment was carried out at a temperature of
The shadow mask is made of Fe2O, Fe50.
Although a grayish-black to black oxide film is formed on alloys mainly composed of iron and nickel, Ni and Cr,
A large amount of Mn was detected in the oxide film.

Furthermore, it was found that this IP membrane had fatal defects such as peeling of the oxide film, an increase in dust in the pipe, and the formation of rust in the manufacturing process A. The reason for this is that alloys mainly composed of iron and nickel are exposed to 11
When annealed at a high temperature of 00°C to 1200°C, impurities contained in the steel, such as Si, Cr, Mn,
It is presumed that this is because the particles are precipitated on the narrow surface of the alloy. Good F'e, 0. -B and Fe, 0. In order to obtain a grayish-black to black oxide film, it is necessary to make the surface of the alloy mainly composed of iron and nickel have a composition ratio of about 11:r↓ to that of high-purity iron.

Therefore, the inventors applied iron plating of about 10 μm to a material whose main components are 36% nickel and iron, and investigated the surface condition of the material.
o Observation was performed using Analyzer (EPMA).

The measurement results are shown in FIG. In Figure 1, the horizontal axis shows E PM.
The acceleration voltage of A is shown by plotting the detected amount of F'e per second on the vertical axis.

Here, (al is a shadow mask made of iron and annealed for 780°Q x 6 minutes in a hydrogen atmosphere.)
b) is a shadow mask made of an alloy whose main components are 36 tinkel and iron. (C) is annealed in vacuum at 1200°C for 60 minutes using the same shadow mask as in (b). (d) is the same shadow mask as (C) with 1.
It is plated with iron to a thickness of approximately 0 μm.

As a result, the surface of the iron-plated shadow mask shows an iron composition ratio close to that of a shadow mask made of iron, and if the desired oxide film is formed on this surface, it can be compared to a shadow mask made of iron. Equivalent Fe, 03 and Fe
, O, can be expected to produce a good grayish-black to black oxide film.

Next, an example in which an oxide film was specifically applied will be described.

Example 1) Thickness 0.15v with 36% nickel and iron as main components
Fine holes in a predetermined pattern are formed in a +ta alloy thin plate by photo-etching. That is, photoresist is coated on both sides of the thin plate, dried, and developed using a mask pattern in the morning light to wash away the photoresist film in the areas where openings are not to be formed. Next, a photo-etching solution is sprayed and photo-etched from both sides to obtain a 14-inch flat mask with a predetermined pattern and shape, for example, fine openings with a hole diameter of 90 μm and a pinch of 0.2 mm. Next 120
After vacuum annealing at a temperature of 0°C, a light leveler is applied to remove wrinkles generated during annealing, and then iron plating is applied. The iron plating solution is a solution of 24 oy7 t of ferrous sulfate, 50 r/J of ferrous chloride, and 301/l of boric acid.
It was set as H3-5.

An iron plate was used as the anode electrode, and plating was performed at a current density of xA/d-. At this time, the plating solution was constantly stirred and the solution temperature was maintained at a temperature of 40°C to 40°C.In this way, the plating thickness was 0.5μ, m, lpm, 2μm, and 3μ.
Samples of 5 μm and 5 μm were prepared in duplicate. After plating, wash with water,
Neutralization.

The mixture was replaced with alcohol and dried at a temperature of 80°C. Next, a flat mask is press-molded. After further degreasing with trichlene, 570° in an atmospheric gas of CO+'C02+O□
An oxide film having a residual film thickness of about 2 μm was formed on each sample at a temperature of C to 600°C. The oxide film thus formed gave good results, with exactly the same color tone and corrosion resistance as the oxide film of the shadow mask made of high-purity iron. Next, the shadow mask of each sample was assembled into a collar tube, and after passing through a normal heat process, it was sealed to complete the tube.The results of the operation test revealed that each sample was caused by thermal expansion of the shadow mask. The deterioration of color purity is tolerable,
In addition, there was no hole in the mask, and the wind pressure resistance was also very good. Furthermore, as a result of measuring the surface condition of the oxidized film on the shadow mask by adding blue to the surface, it was found that there were almost no tusks or cracks in the oxidized film.

Conventional shadow masks that do not damage iron plating and that have nickel as their main component tend to cause peeling and rust, whereas the second embodiment has good corrosion resistance and peels. It is possible to form an oxide film that does not generate oxidation.

Next, change in thermal expansion coefficient of 36% nickel and iron-based alloy plated with iron is 14.1 μm.
, 3 μm, and 5 μrn samples were measured in the second
As shown in the figure. Figure 2 shows the heating temperature on the horizontal pongee and the coefficient of thermal expansion on the vertical axis, where (e) shows the plating thickness of 5 μm, and (f)
shows the characteristics when the plating thickness is 1 μm and 3 μm, respectively.

As is clear from the m12 diagram, the thermal expansion of iron-plated 36-nickel and 1" alloys mainly composed of iron is 0 to 10.
It is less than ~2 x 10'/'O at 0°C, and the influence of the thermal expansion coefficient due to iron plating can be ignored.

However, when 5 μIn iron plating is coated with a thickness of Mj, unevenness in the mask hole of the shadow mask is observed, although it is recognized that the mask hole is uneven. Therefore, the plating thickness is preferably set to 1 μIll to 3 μIn.

Example 2) After press molding and trichlene degreasing, iron plating was performed, and then an oxide film was formed. The other steps and treatment conditions were the same as in Example 1). The resulting shadow mask was as good as in Example 1).

In addition, in the second embodiment, a material mainly composed of 36% nickel and iron was explained, but the present invention can also be applied to materials having various nickel composition ratios such as 42% nickel and 50% nickel. Needless to say, you will get it.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a shadow mask having a good oxide film with good adhesion and free from peeling, dust, cracks, and rust.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the detection of Fe by EPMA, and Figure 2 is a characteristic diagram showing the relationship between temperature change and thermal expansion, with the vertical axis showing the elongation rate. be.

Claims (2)

[Claims] (1) A means for making a metal plate for a shadow mask mainly composed of iron and nickel with a large number of fine holes to make it unnecessary, and a means for forming a grayish-black to black oxide film on the surface of the shadow mask. A method for producing a shadow mask, comprising: (2) The method for manufacturing a shadow mask according to claim A1, wherein the thickness of the iron coating is 5 μm or less.