JP2003213336A - Method of producing sheet metal for shadow mask having excellent etching uniformity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a sheet metal for a shadow mask in which the occurrence of the unevenness of etching is suppressed by uniformizing the reaction of the surface of an electrode with alkali and acid, and which has excellent uniformity in etching. <P>SOLUTION: An Fe-Ni alloy sheet metal after hot working is subjected to cold rolling and annealing in a reducing gas atmosphere at least one or more times, respectively, and is thereafter subjected to finish rolling, and is subsequently subjected to heating treatment at 400 to 700°C, preferably at 550 to 700°C in an inert gas atmosphere to produce a sheet metal for a shadow mask. Preferably, the inert gas consists of, by volume, ≤0.02% oxygen and ≤1.0% (inclusive of zero) hydrogen, and the balance substantially nitrogen, or further, its dew point is controlled to ≤-10°C. More preferably, the annealing in the reducing gas atmosphere is performed at least two or more times. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thin plate for a shadow mask having excellent etching uniformity.

[0002]

2. Description of the Related Art A shadow mask used for color selection of a color cathode ray tube uses 36% Ni-Fe as its material.
Fe-Ni alloys represented by (Invar) alloy and 31% Ni-5% Co-Fe (Super Invar) alloy are used.

Usually, a shadow mask is obtained by hot forging and hot rolling a steel ingot using these materials, or by cold rolling and annealing a hot-worked plate material obtained by a continuous casting method. A thin plate for a shadow mask having a predetermined plate thickness is prepared by performing the process a suitable number of times, and is manufactured through a process of forming an electron beam passage hole by etching and the like.

[0004]

On the other hand, with the recent trend toward larger flat surfaces and higher definition of cathode ray tubes, these shadow mask materials are regarded as a problem of "unevenness" occurring during etching. As a method for suppressing the occurrence of such unevenness, conventionally, various countermeasures such as reduction of Ni segregation, control of crystal orientation, and optimization of surface roughness have been proposed. The current situation is that the outbreak is not completely suppressed.

Therefore, an investigation was made on the mechanism of generation of minute etching unevenness, and in the series of steps of etching the material, the phenomenon during the surface preparation process which is performed prior to surface cleaning or resist coating has a great influence. I found out that there is. That is, it was found that in the reaction with an alkali or an acid during the surface conditioning treatment, the extreme surface layer reacts non-uniformly, thereby hindering the uniformity of resist adhesion and etching processability.

An object of the present invention is to provide a method for producing a thin plate for a shadow mask excellent in etching uniformity, which suppresses the occurrence of etching unevenness by making the reaction with alkali or acid on the extreme surface of the thin plate for a shadow mask uniform. Is to provide.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have used, for example, 36% Ni-Fe alloy and 31% Ni- which are commonly used.
In a thin plate for a shadow mask made of a material such as 5% Co-Fe alloy, a surface morphology effective for suppressing etching unevenness was examined. As a result, it has been found that it is difficult to form all of them with metal, but it is possible to suppress the occurrence of etching unevenness by forming an oxide layer (oxygen bonding layer) in which the oxide is uniformly distributed over the whole. And
With regard to the production of a thin plate, it was found that the uniform oxide layer can be formed by performing a heat treatment in an inert gas atmosphere after the finish cold rolling, and arrived at the present invention.

That is, according to the present invention, Fe-after hot working
After cold rolling and annealing in a reducing gas atmosphere at least once for each Ni-based alloy sheet material, finish rolling is performed, and then 400 to 7 in an inert gas atmosphere.
This is a method for producing a thin plate for a shadow mask excellent in etching uniformity, which is characterized by performing a heat treatment at 00 ° C., preferably 550 to 700 ° C.

Preferably, the inert gas is oxygen: 0.0
2 vol% or less, hydrogen: 1.0 vol% or less (including 0), the balance is substantially nitrogen, or a dew point is -10 ° C or less, and a method for producing a thin plate for a shadow mask excellent in etching uniformity Is. More preferably, it is a method for producing a thin plate for a shadow mask, which is excellent in etching uniformity and which is annealed at least twice in a reducing gas atmosphere.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The feature of the present invention is that the minute etching unevenness that occurs in a mottled pattern greatly depends on the form of the oxide layer formed on the surface of the thin plate, and is the optimum distribution for suppressing the etching unevenness. We have found out the state and found the manufacturing conditions of thin plates that are effective for achieving this.

First, the process of occurrence of etching unevenness was investigated. It was found that the surface cleaning (alkali, acid, etc.) in the etching process, surface treatment for improving the coating property of the resist (alkali, acid, etc.), and perforation were performed. It was found that by etching (ferric chloride, etc.), fine unevenness was formed on the surface. As a result of various studies on the cause of the occurrence, it was found that the conventional surface layer morphology formed on the outermost surface of the thin plate was mainly an oxide layer of Fe (oxygen bonding layer) and a coarse mixed layer between metals. As a result, it was found that this causes unevenness in the reaction with the acid, resulting in uneven etching.

Therefore, if the Fe oxide layer formed on the outermost surface is formed uniformly over the entire surface, or if it is formed over the entire surface as an Fe metal layer, it is possible to suppress defective etching unevenness. Since it is difficult to maintain the production process and uniformity, the inventors have made earnest studies on a method for uniformly and stably forming the Fe oxide on the pole surface layer. As a result, they have found that a desired uniform Fe oxide film can be formed by performing heat treatment in an inert gas atmosphere after finish cold rolling.

Specifically, the Fe-Ni alloy sheet material after hot working is subjected to cold rolling and annealing at least once in a reducing gas atmosphere, respectively, and then finish rolling is carried out. This is a method for manufacturing a thin plate for a shadow mask, which is a heat treatment at 400 to 700 ° C. in an active gas atmosphere.

First, finish rolling is performed to finish a thin plate having a predetermined thickness. In the present invention, it is important that heat treatment at 400 to 700 ° C. is subsequently performed in an inert gas atmosphere. This is especially about a depth of about 1n
Since a uniform Fe oxygen bonding layer is formed up to m, the reaction with the acid or alkali in the shadow mask manufacturing process progresses uniformly, so that etching unevenness due to nonuniform reaction can be suppressed.

In a thin plate for a shadow mask manufactured through an appropriate number of cold rolling and annealing, a reducing gas or an inert gas has conventionally been applied to each annealing atmosphere as needed. However, it is impossible to completely eliminate oxygen in the atmosphere even if the composition of the atmosphere gas is adjusted, considering the manufacturing cost, and it also contains a considerable amount of oxidation potential.

Therefore, even in the process in which the oxidation of the surface of the thin plate cannot be completely prevented, a heat treatment is carried out in an inert gas atmosphere after the finish rolling so that the thin plate has a uniform and stable surface layer. It is possible to form an oxide layer (oxygen bonding layer), and it is possible to suppress the occurrence of unevenness due to a heterogeneous reaction with an acid or an alkali.

First, the inert gas atmosphere of the present invention will be described. It has an appropriate oxidation potential for forming a thin and uniform oxide layer on the surface,
The amount of oxygen is limited in order to reduce the oxidation potential more than necessary. However, as will be described later, conversely, a reducing atmosphere also impairs the effects of the present invention, so an inert gas is selected. In particular,
From the viewpoint of stability of composition control and cost advantage, it is preferable to select nitrogen.

With respect to the oxidation potential, when a large amount of oxygen is present in an inert gas atmosphere, the oxidation of the thin plate surface accelerates to form a harmful thick oxide layer, and the extremely thin surface layer desired by the present invention. It is difficult to obtain a stable Fe oxygen bonding layer. Therefore, specifically, the amount of oxygen is suppressed to 0.02 vol% or less. Preferably 0.01v
It is ol% or less.

In the inert gas atmosphere of the present invention, it is desirable to regulate the reducing gas to a low level, specifically, hydrogen: 1.0 vol% or less (including 0) is preferable. When hydrogen exceeds a certain amount in the inert gas, this causes the reduction reaction to partially proceed,
This is because the surface layer structure in which the Fe metal layer is mixed with the Fe oxide layer is likely to be formed, and the effect of the present invention is hindered. More preferably, it is 0.5 vol% or less (including 0).

When the dew point of the inert gas of the present invention is too high, an oxide develops at the crystal grain boundaries, hindering the formation of a uniform oxide layer. Therefore, the dew point is preferably −10 ° C. or lower.

Next, if the heat treatment temperature is too low, an oxide layer that uniformly protects the surface of the thin plate cannot be formed, resulting in uneven etching. On the other hand, if the heat treatment temperature is too high,
As the oxide layer becomes excessively thick, a fine recrystallized structure is generated on the surface of the thin plate, and the acid reactivity also becomes nonuniform, which promotes uneven etching. Therefore, the heating temperature in the inert gas atmosphere is 400 to 700 ° C. The temperature is preferably 550 ° C or higher, more preferably 600 ° C or higher.

In the present invention in which the heat treatment is carried out in an inert gas atmosphere after the finish rolling, it is preferable that the surface of the cold-rolled sheet material to be provided has no oxide layer as much as possible. For this purpose, it is preferable to carry out cold rolling annealing (intermediate annealing) accompanying the cold rolling process in the reducing atmosphere in the production of the cold rolled sheet material. This is because the intermediate annealing is usually performed at a high temperature of 800 ° C. or higher, so that the selective oxidation of grain boundaries proceeds in an atmosphere having a weak reducing property, and the effect of the heat treatment in the inert atmosphere of the present invention is impaired.

Therefore, in order to obtain the effects of the present invention, at least one of the annealing performed during the production of the cold rolled sheet material, particularly the cold rolling annealing (intermediate annealing) performed an appropriate number of times is in a reducing atmosphere. Then, for example, when performing the cold rolling a plurality of times or performing hot-rolled sheet annealing, etc., when the above-mentioned annealing is required a plurality of times or more, the two or more times, and further, the total annealing should be a reducing atmosphere Is preferred. The reducing atmosphere may be, for example, substantially pure hydrogen or a mixed gas of hydrogen and nitrogen, and 75 vol% or more of hydrogen is preferable as the atmosphere for obtaining a stable reducing surface.

The Fe-Ni alloy used in the present invention may be any alloy applicable to the shadow mask. For example, an alloy containing 30 to 38% by mass of Ni and the balance substantially consisting of Fe. , And its Ni is replaced by 7% or less of Co. Since Mn forms a non-uniform Mn-based oxide on the surface of the thin plate and causes uneven etching, the Mn content is preferably 1.0% or less. It is more preferably 0.5% or less, still more preferably 0.
It is less than 1%.

[0025]

Example A 36% Ni-Fe alloy ingot was melted through vacuum melting, and hot rolled to obtain a hot rolled coil. Using this hot rolled coil as a plate material, cold rolling-annealing in a reducing atmosphere is appropriately performed, and finish rolling is performed to obtain 0.10 to 0.2.
A thin plate coil having a plate thickness of 5 mm was manufactured, and heat treatment was performed under predetermined conditions. In addition, the annealing in the reducing atmosphere is performed by substantially changing the atmosphere to 75 vol% hydrogen and 25 v nitrogen.
It was used as a mixed gas of ol% and applied to all the performed annealing. The structure of the surface layer of the thin plate after the heat treatment was analyzed by ESCA, and the Fe oxidation peak (F
The presence or absence of an e-oxygen bond portion) and a metal peak (metal single portion) was confirmed.

Subsequently, the thin plate obtained by the above heat treatment was subjected to etching to evaluate the resulting unevenness. As a test method, a thin plate as a 50 mm × 200 mm strip-shaped test piece was subjected to an alkali washing-water washing treatment, and then immersed in ferric chloride used for etching. As a result, unevenness was visually observed. Those that are not confirmed are ○, those that are confirmed but have no practical problems are △,
Those that were difficult to practically use were marked with x. The results are shown in Table 1 together with the heat treatment conditions.

[0027]

[Table 1]

From Table 1, the thin plates satisfying the manufacturing method of the present invention, especially the thin plates in which the heating temperature is optimally adjusted and the oxygen or hydrogen contained therein is sufficiently reduced in the heat treatment in the inert gas atmosphere, , Excellent etching uniformity is achieved. Among them, the thin plate No. 4, 5 and 6 are excellent in etching uniformity. Thin plate No. 1,
In the cases of 2, 9 and 10, although the mixing of the metal layer was confirmed in the oxygen bonding layer, the degree thereof was weak, and sufficient etching uniformity could be secured.

On the other hand, in the heat treatment in an inert gas atmosphere, a thin plate whose heating temperature is outside the range of the present invention is a case where oxygen or hydrogen contained in the inert gas atmosphere is sufficiently reduced. However, the etching uniformity is poor.
Thin plate No. In the case of 11, since the heating temperature is low, the nonuniformity of the oxide layer is remarkable. Furthermore, the thin plate No. In No. 12, the oxide layer was excessively thick, and the thin plate surface was disturbed by the recrystallization structure, resulting in remarkable etching unevenness.

[0030]

According to the present invention, it is possible to dramatically improve the uniformity of the surface layer formed on a thin plate, and to provide a thin plate for a shadow mask in which unevenness during etching is suppressed. . Therefore, the technique is indispensable for practical application of the high-definition shadow mask, and has high industrial value.

Claims (5)

[Claims] 1. A Fe-Ni alloy sheet material after hot working is subjected to at least one cold rolling and annealing in a reducing gas atmosphere, and then finish rolling, followed by an inert gas atmosphere. A method for producing a thin plate for a shadow mask excellent in etching uniformity, which comprises performing a heat treatment at 400 to 700 ° C. in the atmosphere. 2. An inert gas atmosphere at 550 to 700 ° C.
The method for producing a thin plate for a shadow mask excellent in etching uniformity according to claim 1, wherein the heat treatment is performed. 3. The inert gas is oxygen: 0.02 vol%
Hereinafter, hydrogen: 1.0 vol% or less (including 0), and the balance is substantially nitrogen.
2. A method for producing a thin plate for a shadow mask, which has excellent etching uniformity. 4. The method for producing a thin plate for a shadow mask excellent in etching uniformity according to claim 1, wherein the dew point of the inert gas is −10 ° C. or lower. 5. The method for producing a thin plate for a shadow mask excellent in etching uniformity according to claim 1, wherein annealing in a reducing gas atmosphere is performed at least twice.