JPS61218051A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE:To simplify the process of manufacturing a shadow mask by using an Fe-Ni alloy containing Cr and Mn for a metallic plate and subjecting the metallic plate to press formation after a black oxide film is formed on the plate. CONSTITUTION:After many openings are formed in a thin metallic plate which principally consists of Fe and Ni and contains at least one of Cr and Mn, this metallic plate is annealed to form a black oxide film on the plate. Next, the metallic plate coated with the black oxide film is formed into a shadow mask. For the above thin metallic plate principally consisting of Fe and Ni and containing at least one of Cr and Mn, a 30-45wt% Fe-Ni alloy containing 0.3-10wt% each of Cr and Mn and an Fe-Ni alloy containing at least 7wt% of Cr can be used. Since the concentration of Cr or Mn in the surface of the metallic plate apt to increase, it is necessary to form an oxide film closely bound to the plate. A shadow mask can be produced by pressing the metallic plate coated with the black oxide film into a given shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a shadow mask for a color picture tube, particularly when the material is mainly composed of Pg and Ni containing at least one of Cr or Mn. The present invention relates to a method of sequentially performing annealing and forming a black oxide film, and then forming the film into a predetermined shape.

[Technical background of the invention and its problems]

The so-called internal parts of a color picture tube, such as the shadow mask, frame, inner shield, and bimetal, have better etching and moldability than conventional ones, and it is easy to form an oxide film on their surface that contributes to reducing electron beam reflection. ,
It is made of rimmed steel, Al-killed steel, or the like. However, in order to respond to various new media these days, higher quality color picture tubes are required, that is, so-called easy-to-see and ultra-fine display images, and shadow masks made of the above-mentioned rimmed steel or Al-killed steel are required. , there have been problems with using frames, inner shields, bimetals, etc.

That is, during operation of the color picture tube, the temperature of each of the above-mentioned members rises to 30 to 100[deg.] C., and so-called doming occurs due to distortion in the shape of the shadow mask due to thermal expansion, for example. As a result, a shift occurs in the relative positional relationship between the shadow mask and the phosphor surface, resulting in a color shift called vinylity shift (FD). In particular, in high-quality color picture tubes, the aperture diameter and the aperture pitch of the shadow mask are very small, so the relative misalignment ratio becomes large. The parts are no longer practical.

Therefore, conventionally, the materials used to form this type of pipe internal parts were
Ni-Fe alloys with a small coefficient of thermal expansion, such as amber (
35Ni-Fe) can be used, for example, in
No. 25446, JP-A-50-58977, JP-A-5O
-6864) No. 0, etc. However,
This type of N1-Fe alloy has the drawback of poor thermal conductivity and easy heat accumulation.

As a solution to this problem, attempts have been made to form a black oxide film with excellent thermal conductivity. It was extremely difficult to form a black oxide film to a predetermined thickness due to the fact that amber itself has excellent corrosion resistance.

[Purpose of the invention]

The present invention is a method for manufacturing a shadow mask using an amber-based alloy, which allows a black oxide film with excellent thermal conductivity to be easily formed to a predetermined thickness, and in which the annealing process and the heat treatment process of the black oxide film forming process are performed continuously. It is an object of the present invention to provide a method for manufacturing a shadow mask, which can greatly simplify the manufacturing process.

[Summary of the invention]

The present invention includes a step of drilling a large number of holes in a thin metal plate mainly composed of Fe and Ni containing at least one of Cr or Mn, and annealing the metal plate in which the large number of holes have been drilled. This method of manufacturing a shadow mask includes at least the steps of: forming a black oxide film on the annealed metal plate; and molding the metal plate on which the black oxide film is formed.

In the present invention, the step of first drilling a large number of holes can be performed using a conventional method, such as pre-sensitized coating, exposure,
By performing development, burning, and etching, a flat mask with a large number of beam apertures is obtained.

After cleaning, drying and shearing the flat mask, proceed to the fire annealing process.

In other words, in the present invention, the metal plate 1cFe-
The main feature is that N1 alloy is used, a black oxide film is formed after annealing, and then press molding is performed. In particular, Cr or Mn tends to concentrate on the surface of this metal plate, and Crx (or Mn
) A highly adhesive oxide film with a structure of Nl, Fe5-x-, O, is created, so it has good adhesiveness and does not peel off. The temperature at which the oxide film is deposited is usually 570 to 900°C, and as mentioned above, when hydrogen or nitrogen annealing is performed,
You can choose a low oxidation temperature.

Next, the metal plate on which the black oxide film has been formed is formed into a predetermined shape as a shadow mask by pressing or the like. In addition, when conventional rimmed steel or Al guild steel is used, if a post-forming and forming process is performed after forming a black oxide film, the black oxide film may peel off, which is not practical, but in the case of the method of the present invention, As mentioned above, since a strong black oxide film with excellent adhesion was formed, the black oxide film was maintained without peeling even after molding.

In the present invention, the thin metal mainly composed of Fe and Ni containing at least one of Cr or Mn includes C
Examples include a 30 to 45 wt% Fe-Ni alloy to which 0.3 to 10 wt% of r, Mn is added, and the aforementioned Fe-Ni alloy to which OCO of 7 wt.'S or less is added.

The annealing process may be performed in a vacuum, hydrogen, or nitrogen atmosphere, but in order to lower the 0.2% proof stress during forming and make it easier to form, it is necessary to remove as much C as possible inside the metal plate. Therefore, vacuum annealing at 10-' Torr or less is most convenient. However, the amount of Cr or Mn added increases. Since the 0.2% yield strength also decreases, the process may be carried out in a hydrogen or nitrogen atmosphere. When hydrogen or nitrogen is used, the surface of the metal plate is hardened by absorbing hydrogen or nitrogen, but at the same time, the density of defects on the surface increases, and when a black oxide film is formed, oxygen is absorbed into the surface of the metal plate. It has the advantage of being well diffused and growing faster. Therefore, if you want to grow a thick black oxide film and improve formability, it is better to perform vacuum annealing followed by hydrogen or nitrogen annealing, or hydrogen or nitrogen annealing followed by vacuum annealing. .

The annealing temperature is usually preferably 1000°C or higher, but if the shape during forming is not a big problem, the annealing temperature is 700°C to 100°C.
There is no problem even if the temperature is 0°C.

It is also a good idea to generate a black oxide film by returning the metal plate to room temperature and then heating it again in an oxidizing atmosphere.
As a simple method, it is preferable to oxidize in a furnace after annealing because it is convenient. In particular, this method is efficient because this metal plate has good corrosion resistance and is difficult to oxidize unless it is heated to a temperature of 550° C. or higher. As the oxidizing atmosphere, use an oxidizing gas such as COl +01 *H,0,
Adjust the oxygen partial pressure so that α-FetO is difficult to form.

[Embodiments of the invention]

Below, 2Cr is used as a shadow mask material made of an alloy mainly composed of Fe and Ni containing Cr or Mn.
-36Ni-re (weight%), 2Mn-36N
An example of the present invention using l-Fe alloy will be described.

This alloy is C20.01.84:0.15, P
:0. O05,8:0. Contains impurities of OOl (both weight 1).

(Example 1) A flat mask having a large number of pores having a desired hole size is obtained by ordinary photoetching using an alloy having the above composition as a material. This mask is then press-molded to obtain the desired curved shape, but if the yield point strength of the mask material is high, the spherical shape will collapse due to springback.
The molded mask cannot be put to practical use. For this reason, it is necessary to lower the yield strength by 0.2% by annealing to a value that allows a high-quality press-formed product to be obtained. The 0.21 proof stress that can be normally press-formed is 20Kg/m'',
To lower it to this value, K 10-”Torr 1000
It was annealed for a period of 0.degree. C. under vacuum for 10 minutes. then 7
It was cooled to 50° C. and air was introduced at this temperature for addition. At this time, during the initial 10 minutes, the air flow rate is suppressed and the Crx (or Mn)Ni, which is dense and has good adhesion, is
Since it was necessary to grow an oxide film of , Fe3-, , O, the inflow was carried out while maintaining the pressure inside the furnace at 10'rorr. For the next 20 minutes, the pressure inside the furnace was kept at the same level as atmospheric pressure and the inflow was carried out.

In this way, when the film of the flat mask with the black oxide film was analyzed using X-ray diffraction and an ion microanalyzer, the structure was found to be Cr! (or Mn) N
t, Fas-x-y o, and C is added to the oxide film and metal interface.
r was concentrated. The film had a thickness of 1.2 μm and had sufficient blackness and adhesion. The adhesion was evaluated by applying Sellotape to the curvature after the 90' curvature test and performing a peeling test of the blackened film. Further, the state of the blackened film was observed using a scanning electron microscope, and it was confirmed that the blackened film was dense and free of cracks and pinholes.

This flat mask was molded at room temperature using a conventional method to complete a shadow mask with a desired curved surface. The black oxide film did not peel off even at the bent portion and had sufficient strength.

(Example 2) After etching a similar alloy by a similar method, 1100
Hydrogen annealing was performed at ℃. Cool it to vk690℃,
Thereafter, water vapor was allowed to flow in for 30 minutes at this temperature to deposit a black oxide film. In the case of water vapor, the initial stage 1 is the same as before.
The flow rate was suppressed during 0 minutes, and increased during the latter 20 minutes. When the flat mask produced in this manner was press-molded in the same manner, a shadow mask was completed that did not peel off even at the folded portions.

In the above embodiments, 2Cr-
Although 35Ni-Fe and 2Mn-36Ni-Fe alloys were used, the present invention is not limited thereto;
It goes without saying that any alloy whose main components are iron and nickel, including super amber, such as Fe alloy or 32Ni-5Co, can be similarly applied. Furthermore, it goes without saying that this manufacturing method is applicable not only to shadow masks but also to color picture tubes as long as the mask frame and inner silt are made of an alloy containing iron and nickel as their main components.

〔Effect of the invention〕

As described above, according to the present invention, blackening can be efficiently performed from annealing, and a black oxide film of sufficient thickness can be produced. It also has the advantage of preventing the formation of red rust during storage of flat masks, making it extremely effective industrially.

Claims (1)

[Claims] 1) Fe and Ni containing at least one of Cr or Mn
a step of drilling a large number of holes in a thin metal plate mainly composed of a metal plate, an annealing of the metal plate with the large number of holes, and a step of forming a black oxide film on the annealed metal plate. A method for manufacturing a shadow mask, comprising at least the steps of forming a black oxide film, and molding a metal plate on which the black oxide film is formed. 2) The method for manufacturing a shadow mask according to claim 1, wherein a step of continuously forming a black oxide film is performed without returning the material to room temperature after the annealing step. 3) The method for manufacturing a shadow mask according to claim 1, characterized in that a Cr or Mn concentrated layer is formed at the interface between the black oxide film and the thin metal plate.