JP2001181741A - Method for producing low thermal expansion alloy thin sheet excellent in etching property, thin sheet for shadow mask and shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an Fe-Ni series or Fe-Ni-Co series alloy thin sheet excellent in etching properties and to obtain a thin sheet for a shadow mask excellent in various characteristics and a shadow mask. SOLUTION: In the method for producing a low thermal expansion alloy thin sheet of an Fe-Ni series containing, by mass, 30 to 50% Ni or of an Fe-Ni- Co series containing <=7% Co and 27 to 40% (Ni+Co), at the time of forming a laminated and solidified ingot in which the angle between the substantial solidifying direction and the growing direction of dendrite is controlled to 50 deg.C or more, preferably to 70 deg.C or more on the acute angle side into a thin sheet, blooming forging is performed in such a manner that the substantial solidifying direction comes to the sheet thickness direction of the thin sheet, and hot rolling and cold rolling are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a low-thermal-expansion alloy thin plate for use in a shadow mask or a lead frame which is subjected to fine etching, a thin plate for a shadow mask, and a shadow mask.

[0002]

2. Description of the Related Art In the case of a high-definition display such as a computer display, the electron beam passage holes of a shadow mask have a diameter of about 120 μm and a size of about one million through the photoetching treatment of a ferric chloride solution or the like. The above must be precisely drilled. The quality of the etching property affects the quality of uniform fineness of the electron beam passage hole. To this end, efforts are being made to improve the quality of the material as well as to improve the etching technology. However, with regard to the raw material, the defectiveness of the hole shape due to the poor etching still frequently occurs, and it is desired to provide a raw material having a good etching property.

[0003]

The poor etching is visually observed as streak-like etching unevenness extending in the rolling direction on the plane of the thin plate. This unevenness is caused by concentration segregation of Ni or Ni or Co, and several techniques regarding diffusion heat treatment have been proposed to alleviate segregation. However, in practice, segregation generated in the steel ingot or slab is not sufficiently mitigated by these heat treatments, resulting in poor quality as segregation streaks in the final product.

To solve such a problem, Japanese Patent Laid-Open No. 11-5 / 1999
In the article No. 0146, the sectional shape of the prismatic steel ingot or the prismatic slab formed by the continuous casting method is specified to reduce segregation. However, there still remains a surface where the etching unevenness is not sufficiently suppressed even by this means, and there is room for further improvement in this subject. Therefore, the present invention provides an F
Provided is a method for producing an e-Ni-based or Fe-Ni-Co-based alloy thin plate, and a shadow mask thin plate having excellent properties.
It is an object to provide a shadow mask.

[0005]

Means for Solving the Problems First, the present inventors studied the cause of the etching failure that occurs in a thin plate and found that the cause was microsegregation caused by the dendrite structure found in the cast structure. I stopped. Next, the factors that affect the etching property are examined, and the factors that greatly affect the dendrite structure in the steel ingot during the plastic working (bulking forging, hot rolling, cold rolling) in the elongation direction are considered. I found that it depends. Then, as a result of a thorough study on the relationship between the elongation direction and the etching property during the plastic working, the substantial solidification direction of the steel ingot was determined using a laminated solidified steel ingot with the optimally adjusted dendrite growth direction. Has been found to be effective in improving the etching properties if it is finally stretched so as to be in the thickness direction of the alloy thin plate.

That is, the present invention relates to a method for producing Ni: 3
Fe-Ni containing 0 to 50% or Fe-N containing 7% or less of Co (Ni + Co) of 27 to 40%
In the method for producing an i-Co-based low-thermal-expansion alloy sheet, when the laminated solidified steel ingot in which the angle between the substantial solidification direction and the dendrite growth direction is adjusted to 50 ° or more on the acute angle side is made into a thin sheet, This is a method for producing a low-thermal-expansion alloy thin plate having excellent etching properties, which comprises performing forging and forging so that the substantial solidification direction is the thickness direction of the thin plate, and performing hot rolling and cold rolling. Preferably, the angle between the substantial solidification direction of the steel ingot and the dendrite growth direction is 7 at the acute angle side.
0 ° or more.

[0007] In addition to the above invention, there is further provided a method for producing a low thermal expansion alloy sheet having excellent etching properties, wherein diffusion heat treatment is performed before or after or before or after bulk forging or hot rolling. . A thin plate for a shadow mask manufactured by the method for manufacturing a low thermal expansion alloy thin plate of the present invention, and a shadow mask formed by etching an electron beam passage hole in the thin plate for a shadow mask.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The feature of the present invention is that the cause of the etching failure occurring in a product is micro segregation caused by the dendrite structure found in the cast structure, and the cause is the cause during the plastic working. It has been found that the correlation between the extending direction and the solidified structure largely resolves the problem, and the preferable correlation condition between the extending direction and the solidified structure is also clarified.

[0009] The present inventors have investigated the mechanism of etching failure occurring in products, and have found that this largely depends on microsegregation caused by a dendrite structure found in a cast structure. In other words, within the steel ingot or slab, there are columnar crystals and equiaxed structures in various directions, and as a cause of micro-segregation, the composition and structure at each part of the product are linked unevenly, and as a result, each of the resulting parts The difference between the etching rates directly results in uneven etching. Therefore, the present inventors studied a casting structure preferable for suppressing such micro-segregation, and also studied a processing condition for a thin sheet optimal for a steel ingot having the casting structure.

[0010] First, the present inventors performed plastic working (ingot forging, ingot forging,
Hot rolling, cold rolling), and the structure of the thin plate produced thereby was examined. As a result, it has been found that the plastic working substantially in the direction along the surface is effective for suppressing the etching unevenness in the surface portion where a large number of dendrites exist in the cast structure.

That is, in addition to slab forging in the direction along the surface where many dendrites are gathered, hot rolling and cold rolling in the same direction are performed, so that the dendrite group in the cast structure can be efficiently formed. It can be spread, micro-segregation caused by the dendrite structure can be made uniform throughout the thin plate, and the above-mentioned etching unevenness caused by the composition and structure unevenness can be suppressed.

In this case, a steel ingot suitable for the application is preferably one in which the dendrites in the cast structure are easily arranged in layers.
In the present invention, it is desirable to use a laminated solidified steel ingot. That is, in the laminated solidified steel ingot, the dendrite growth direction in the casting structure can be adjusted in a direction laid down with respect to the substantial solidification direction of the steel ingot, and the layer of the laid down dendrite is formed. . Therefore, slab forging so that the direction perpendicular to the substantial solidification direction in the lamination solidification is the main elongation direction, hot rolling in the same direction in addition, cold rolling, and finally the If an alloy thin plate whose substantial solidification direction is the plate thickness direction is used, the site of local microsegregation can be significantly reduced in the manufactured thin plate structure. On the rolled surface of the final sheet to be etched, the micro-segregation is uniform over the entire rolled surface, and the micro-segregation has a structure in which the micro-segregation narrowly overlaps in a layered manner in the plate thickness direction. Become the best organization to be.

[0013] As described above, in the method for producing an alloy sheet according to the present invention, it is important to adjust the direction of growth of the dendrite and the direction of processing into a thin sheet. It is important to adjust the spreading direction of the solidified steel ingot as well as to make the adjustment in advance. Specifically, as shown in FIG. 1, when a laminated solidified steel ingot whose angle between the substantial solidification direction and the dendrite growth direction is adjusted to 50 ° or more on the acute angle side is made into a thin plate, the substantial This is a method for producing an alloy thin plate in which slab forging is performed so that the solidification direction is the thickness direction of the thin plate, and hot rolling and cold rolling are performed. Preferably, the angle between the substantial solidification direction and the dendrite growth direction is adjusted to 70 ° or more on the acute angle side.

The laminated solidified steel ingot used in the present invention includes, for example, VAR (vacuum arc remelting), ESR (electroslag remelting), PAR (plasma arc remelting), EBR (electron beam remelting). Method may be used, and it is desirable to use a steel ingot which does not disturb the solidification direction by laminating and solidifying such methods or other melting and casting methods. Further, the shape of the steel ingot at this time is not limited to a specific shape of the steel ingot, such as a cylindrical or rectangular parallelepiped steel ingot.

[0015] With respect to these laminated solidified steel ingots, the angle between the substantial solidification direction and the dendrite growth direction is adjusted at a site where the solidification structure is stable, thereby achieving the effects of the present invention accurately. It is desired in doing. In particular,
As shown in FIG. 1, this is a middle part along the substantial solidification direction of the laminated solidified steel ingot, and is a part halfway in the center (radius) direction from the outer periphery of the middle part.

In order to properly achieve the effects of the present invention, it is desired that the solidified solidified steel ingot to be provided has a stable solidified structure. One or both of the upper and lower portions of the steel ingot relative to the substantial solidification direction of the laminated solidified steel ingot,
It may be removed in advance by cutting or the like.

In the method for producing a thin plate according to the present invention, the action of compressing the steel ingot in the substantial solidification direction at a high working ratio, that is, the direction in which the dendrite grows is set to the substantial solidification direction of the steel ingot. The effect of making the dendrite group lie down is achieved, and efficient expansion of the dendrite group is achieved. In addition, dendrites in the cast structure can be deformed into layers, and the distance between the layers can be reduced. As a result, the micro-segregation due to the dendrite structure can be present at a narrow interval in the entire thin plate, so that the above-mentioned uneven etching can be further suppressed as the dendrite spreads. FIG. 2 is shown as an example for explaining the operation.

In addition, in the case of the present invention, diffusion heat treatment (soaking treatment) before or after or before or after the bulk forging or hot rolling is effective for further improving the etching property. In particular, in the diffusion heat treatment after slab forging, the diffusion distance due to the diffusion heat treatment is short because the size and interval of microsegregation due to the dendrite structure are small, and the diffusion effect by the treatment is reduced. Can be used effectively. Specifically, it is a diffusion heat treatment at 1200 to 1400 ° C.

Further, in the plastic working (bulking forging, hot rolling, cold rolling) process according to the method for producing a thin plate of the present invention, the final plastic working ratio (cross sectional area of steel ingot before bulk forging / cold rolling) It is preferable to perform bulk forging, hot rolling and cold rolling so that the cross-sectional area of the thin plate after cold rolling becomes larger in a cross-sectional area perpendicular to the elongation direction. In particular, the plastic working ratio at the time of slab forging (the cross-sectional area of the steel ingot before the slab forging / the cross-sectional area of the slab after the slab forging) is increased in the cross-sectional area perpendicular to the drawing direction. This makes it possible to reduce the size of the micro-segregation due to the dendrite structure and to reduce the interval. Further, it is possible to further reduce etching defects caused by Ni or Ni, Co segregation which is a problem in products.

Further, in performing the ingot sizing according to the present invention, the dendrite structure in the steel ingot before the ingot forging is previously adjusted to be small, so that the unit of segregation can be reduced, and the segregation streak can be reduced. It is valid. As a result, the size of microsegregation due to the dendrite structure is reduced,
And the interval can be narrowed, and N which is a problem in products
Etching defects due to i or Ni, Co segregation can be further reduced. As a means for adjusting the dendrite structure in the steel ingot to a small value in advance, for example, increasing the cooling rate at the time of casting and solidifying.

In addition, the composition of the low-thermal-expansion alloy sheet necessary for achieving the effects of the production method of the present invention will be described. Ni is an Fe-Ni alloy or Fe-Ni-C
It is an element that greatly affects the low thermal expansion characteristics of an o-based alloy. Electronic component materials used for IC lead frames and shadow masks need to have a thermal expansion coefficient close to that of glass materials used for Si chips, packages, and cathode ray tubes. To prevent. Therefore, in the present invention, Ni is set to 30 to 50 (% by mass) as a content that achieves the above effects.

In addition, Co is effective in further improving the low thermal expansion characteristics by substituting a part of the amount of Ni constituting the Fe-Ni alloy. In the Fe—Ni—Co-based low thermal expansion alloy thin plate of the present invention, Co was set to 7 (% by mass) or less and (Ni + Co) was set to 27 to 40 (% by mass).

As described above, when the low thermal expansion alloy thin plate produced by the production method of the present invention is applied to a thin plate for a shadow mask, it is excellent in suppressing the etching unevenness generated when the electron beam passage hole is formed by etching, and has high definition. Degree of shadow mask can be achieved.

[0024]

Embodiments of the present invention will be described below. First, using VAR and ESR, the conditions for producing the steel ingot were changed, and columnar steel ingots of Fe—Ni-based alloys and Fe—Ni—Co-based alloys having the component compositions shown in Table 1 were produced. Then, when the drawing is performed so that the substantial solidification direction in these ingots is the thickness direction of the alloy thin plate, the substantial solidification direction and the dendrite growth direction of the ingot prepared in advance under the same conditions are compared. The angle θ was measured. In addition,
The measurement site is an intermediate part along the substantial solidification direction of the steel ingot, and is a part that is located halfway in the radial direction from the outer periphery of the intermediate part (see FIG. 1).

Then, the prepared steel ingot is subjected to slab forging so that the direction perpendicular to the substantial solidification direction is the main drawing direction, and hot rolling and cold rolling are performed in the same direction. Through this, an alloy thin plate whose substantial solidification direction was the thickness direction of the alloy thin plate was finished, and its etching property was evaluated. In addition, a part was subjected to a diffusion heat treatment at 1200 ° C. after the forging.

The comparative example is a laminated solidified steel ingot having an angle θ of 30 ° between the substantial solidification direction and the dendrite growth direction, and the substantial solidification direction is the thickness direction of the final thin plate. It is an extension.

The evaluation of the etching property was evaluated on a five-point scale (1: excellent → 5: inferior) based on the degree of segregation of the thin plate affecting the etching property. FIG. 3 is a schematic diagram showing the Ni concentration distribution of the cold-rolled thin plate analyzed by EPMA in terms of color shading, and segregation is represented by an extreme change in shading. FIG.
(A) has a uniform change in shading, the degree of segregation is slight, and the size of the unevenness in segregation is small, which corresponds to 2 of the above five-grade evaluation. On the other hand, FIG. 3B in which the change in shading is remarkable corresponds to 4 of the above-mentioned five-grade evaluation.

At the same time, etching was performed on each thin plate, and streak-like unevenness existing on the etched surface was confirmed by visual observation. Etching conditions were as follows: a photoresist film having an opening of φ200 μm was formed on the surface of the sample, and then a 60 ° C. ×
Spray etching was performed for 5 minutes.

[0029]

[Table 1]

As is clear from Table 1, it is understood that the degree of segregation is small and the size of the unevenness of segregation is small in the thin plate manufactured by the manufacturing method satisfying the present invention. Then, the streak-like unevenness observed when the thin plate of the present invention is etched is slight and has excellent etching properties. Further, it is found that segregation is further reduced in the case where the diffusion heat treatment is performed after the forging, and the etching property is improved.

[0031]

According to the present invention, it is possible to provide a low-thermal-expansion alloy sheet in which poor etching is suppressed. As a result, the alloy sheet according to the present invention can achieve excellent etching properties and can respond to further improvement in the quality of electronic component materials used for shadow masks, IC lead frames, and the like. The effect is high.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a production method of the present invention.

FIG. 2 is a schematic view showing an example of the production method of the present invention.

FIG. 3 is a schematic diagram showing the state of segregation of Ni.

Claims (5)

[Claims] 1. An F containing 30 to 50% of Ni by mass%.
e-Ni or Co: contains 7% or less (Ni + C
o) In the method for producing an Fe—Ni—Co-based low thermal expansion alloy sheet having 27 to 40%, the angle between the substantial solidification direction and the dendrite growth direction was adjusted to 50 ° or more on the acute angle side. When the laminated solidified steel ingot is made into a thin plate, forging is performed so that the substantial solidification direction is the thickness direction of the thin plate,
A method for producing a low-thermal-expansion alloy sheet excellent in etching properties, characterized by performing hot rolling and cold rolling. 2. The low thermal expansion excellent in etching properties according to claim 1, wherein the angle between the substantial solidification direction of the steel ingot and the dendrite growth direction is 70 ° or more on the acute angle side. Manufacturing method of alloy sheet. 3. The method for producing a low thermal expansion alloy sheet excellent in etching properties according to claim 1 or 2, wherein a diffusion heat treatment is performed before or after or before or after slab forging or hot rolling. 4. A thin plate for a shadow mask, which is produced by the method for producing a low thermal expansion alloy thin plate according to any one of claims 1 to 3. 5. A shadow mask, wherein an electron beam passage hole is formed in the thin plate for a shadow mask according to claim 4.